Pressure injury treatment by intermittent electrical stimulation (PROTECT-2): protocol for a multicenter randomized clinical trial

BACKGROUND

Pressure ulcers account for a substantial fraction of hospital-acquired pathology, with consequent morbidity and economic cost. Treatments are largely focused on preventing further injury, whereas interventions that facilitate healing remain limited. Intermittent electrical stimulation (IES) increases local blood flow and redistributes pressure from muscle-bone interfaces, thus potentially reducing ulcer progression and facilitating healing.

METHODS

The Pressure Injury Treatment by Intermittent Electrical Stimulation (PROTECT-2) trial will be a parallel-arm multicenter randomized trial to test the hypothesis that IES combined with routine care reduces sacral and ischial pressure injury over time compared to routine care alone. We plan to enroll 548 patients across various centers. Hospitalized patients with stage 1 or stage 2 sacral or ischial pressure injuries will be randomized to IES and routine care or routine care alone. Wound stage will be followed until death, discharge, or the development of an exclusion criteria for up to 3 months. The primary endpoint will be pressure injury score measured over time.

DISCUSSION

Sacral and ischial pressure injuries present a burden to hospitalized patients with both clinical and economic consequences. The PROTECT-2 trial will evaluate whether IES is an effective intervention and thus reduces progression of stage 1 and stage 2 sacral and ischial pressure injuries.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05085288 Registered October 20, 2021.

Association Between Age- and Sex-Specific Body Mass Index Percentile and Multiple Intubation Attempts: A Retrospective Cohort Analysis

BACKGROUND

Obesity distorts airways and slightly complicates intubations in adults, but whether obesity complicates pediatric intubations remains unclear. We, therefore, tested the primary hypothesis that increasing age- and sex-specific body mass index (BMI) percentile is associated with difficult intubation, defined as >1 intubation attempt.

METHODS

We conducted a retrospective analysis of pediatric patients between 2 and 18 years of age who had noncardiac surgery with oral endotracheal intubation. We assessed the association between BMI percentile and difficult intubation, defined as >1 intubation attempt, using a confounder-adjusted multivariable logistic regression model. Secondarily, we assessed whether the main association depended on preoperative substantial airway abnormality status or age group.

RESULTS

A total of 9339 patients were included in the analysis. Median [quartiles] age- and sex-specific BMI percentile was 70 [33, 93], and 492 (5.3%) patients had difficult intubation. There was no apparent association between age- and sex-specific BMI percentile and difficult intubation. The estimated odds ratio (OR) for having difficult intubation for a 10-unit increase in BMI percentile was 0.98 (95% confidence interval [CI], 0.95-1.005) and was consistent across the 3 age groups of early childhood, middle childhood, and early adolescence (interaction P = .53). Patients with preoperative substantial airway abnormalities had lower odds of difficult intubation per 10-unit increase in BMI percentile, with OR (95% CI) of 0.83 (0.70-0.98), P = .01.

CONCLUSIONS

Age- and sex-specific BMI percentile was not associated with difficult intubation in children between 2 and 18 years of age. As in adults, obesity in children does not much complicate intubation.

Smallest Clinically Meaningful Improvement in Amputation-Related Pain and Brief Pain Inventory Scores as Defined by Patient Reports of Global Improvement After Cryoneurolysis: a Retrospective Analysis of a Randomized, Controlled Clinical Trial

BACKGROUND

The smallest meaningful improvement in pain scores (minimal clinically important difference [MCID]) after an analgesic intervention is essential information when both interpreting published data and designing a clinical trial. However, limited information is available for patients with chronic pain conditions, and what is published is derived from studies involving pharmacologic and psychological interventions. We here calculate these values based on data collected from 144 participants of a previously published multicenter clinical trial investigating the effects of a single treatment with percutaneous cryoneurolysis.

METHODS

In the original trial, we enrolled patients with a lower-limb amputation and established phantom pain. Each received a single-injection femoral and sciatic nerve block with lidocaine and was subsequently randomized to receive either ultrasound-guided percutaneous cryoneurolysis or sham treatment at these same locations. Investigators, participants, and clinical staff were masked to treatment group assignment with the exception of the treating physician performing the cryoneurolysis, who had no subsequent participant interaction. At both baseline and 4 months (primary end point), participants rated their phantom limb pain based on a numeric rating scale (NRS) and their interference of pain on physical and emotional functioning as measured with the Brief Pain Inventory's interference subscale. They subsequently qualitatively defined the change using the 7-point ordinal Patient Global Impression of Change (PGIC). The smallest clinically meaningful improvements in phantom limb pain and Brief Pain Inventory scores were calculated using an anchor-based method based on the PGIC.

RESULTS

The median (interquartile range [IQR]) phantom pain NRS (0-10) improvements at 4 months considered small, medium, and large were 1 [1-1], 3 [3-4], and 4 [3-6], respectively. The median improvements in the Brief Pain Inventory interference subscale (0-70) associated with a small, medium, and large analgesic changes were 16 [6-18], 24 [22-31], and 34 [22-46]. The proportions of patients that experienced PGIC ≥5 were 33% and 36% in the active and placebo groups, respectively. The relative risk of a patient experiencing PGIC ≥5 in the active group compared to the sham group with 95% confidence interval was 0.9 (0.6-1.4), P = .667.

CONCLUSIONS

Amputees with phantom limb pain treated with percutaneous cryoneurolysis rate analgesic improvements as clinically meaningful similar to pharmacologic treatments, although their MCID for the Brief Pain Inventory was somewhat larger than previously published values. This information on patient-defined clinically meaningful improvements will facilitate interpretation of available studies and guide future trial design.

Association between preoperative anemia optimization and major complications after non-cardiac surgery: a retrospective analysis

BACKGROUND

Anemia is common in the preoperative setting and associated with increased postoperative complications and mortality. However, it is unclear if preoperative anemia optimization reduces postoperative complications. We aimed to assess the association between preoperative anemia optimization and a composite endpoint of major cardiovascular, renal, and pulmonary complications and all-cause mortality within 30 days after noncardiac surgery in adult patients.

METHODS

In this retrospective analysis preoperative anemia was defined as hemoglobin concentration below 12.0 g.dl-1 in women and 13.0 g.dl-1 in men within 6 months before surgery. A propensity score-based generalized estimating equation analysis was used to determine the association between preoperative anemia optimization and the primary outcome. Moreover, mediation analysis was conducted to investigate whether intraoperative red blood cell transfusion or duration of intraoperative hypotension were mediators of the relation between anemia optimization and the primary outcome.

RESULTS

Fifty-seven hundred anemia optimized, and 8721 non-optimized patients met study criteria. The proportion of patients having any component of the composite of major complications and all-cause mortality was 21.5% in the anemia-optimized versus 18.0% in the non-optimized, with confounder-adjusted odds ratio estimate of 0.99 (95% CI 0.86‒1.15) for anemia optimization versus non-optimization, p = 0.90. Intraoperative red blood cell transfusion had a minor mediation effect on the relationship between preoperative anemia optimization and the primary outcome, whereas duration of intraoperative hypotension was not found to be a mediator.

CONCLUSION

Preoperative anemia optimization did not appear to be associated with a composite outcome of major in-hospital postoperative cardiovascular, renal, and pulmonary complications and all-cause in-hospital mortality.

Systematic Reviews and Meta-analyses in Regional Anesthesia and Pain Medicine (Part II): Guidelines for Performing the Systematic Review

In Part I of this series, we provide guidance for preparing a systematic review protocol. In this article, we highlight important steps and supplement with exemplars on conducting and reporting the results of a systematic review. We suggest how authors can manage protocol violations, multiplicity of outcomes and analyses, and heterogeneity. The quality (certainty) of the evidence and strength of recommendations should follow the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach. It is our goal that Part II of this series provides valid guidance to authors and peer reviewers who conduct systematic reviews to adhere to important constructs of transparency, structure, reproducibility, and accountability. This will likely result in more rigorous systematic reviews being submitted for publication to the journals like Regional Anesthesia & Pain Medicine and Anesthesia & Analgesia .

Systematic Reviews and Meta-analyses in Regional Anesthesia and Pain Medicine (Part I): Guidelines for Preparing the Review Protocol

Comprehensive resources exist on how to plan a systematic review and meta-analysis. The objective of this article is to provide guidance to authors preparing their systematic review protocol in the fields of regional anesthesia and pain medicine. The focus is on systematic reviews of health care interventions, with or without an aggregate data meta-analysis. We describe and discuss elements of the systematic review methodology that review authors should prespecify, plan, and document in their protocol before commencing the review. Importantly, authors should explain their rationale for planning their systematic review and describe the PICO framework-participants (P), interventions (I), comparators (C), outcomes (O)-and related elements central to constructing their clinical question, framing an informative review title, determining the scope of the review, designing the search strategy, specifying the eligibility criteria, and identifying potential sources of heterogeneity. We highlight the importance of authors defining and prioritizing the primary outcome, defining eligibility criteria for selecting studies, and documenting sources of information and search strategies. The review protocol should also document methods used to evaluate risk of bias, quality (certainty) of the evidence, and heterogeneity of results. Furthermore, the authors should describe their plans for managing key data elements, the statistical construct used to estimate the intervention effect, methods of evidence synthesis and meta-analysis, and conditions when meta-analysis may not be possible, including the provision of practical solutions. Authors should provide enough detail in their protocol so that the readers could conduct the study themselves.

Association Between Cannabis Use and Opioid Consumption, Pain, and Respiratory Complications After Surgery: A Retrospective Cohort Analysis

BACKGROUND

Cannabis is a widely used illicit drug with effects on different pain pathways. However, interactions between cannabis and postoperative pain are unclear. Cannabis smoking also affects the lungs, but the impact of cannabis use on postoperative pulmonary complications is unknown. We hypothesized that preoperative cannabis use in adults having elective surgery is associated with higher postoperative opioid consumption. Secondarily, we tested the hypothesis that cannabis use is associated with higher pain scores, hypoxemia (oxygen saturation [Spo2]/fraction of inspired oxygen [Fio2] ratio), and higher postoperative pulmonary complications compared to nonuse of cannabis.

METHODS

In this retrospective study, we included adult patients who had elective surgeries at Cleveland Clinic Main Campus between January 2010 and December 2020. The exposure was use of cannabis within 30 days before surgery, and the control group never used cannabis. Patients who had regional anesthesia or chronic pain diagnosis were excluded. The primary outcome was postoperative opioid consumption; 3 secondary outcomes were time-weighted average (TWA) postoperative pain score, TWA Spo2/Fio2 ratio, and composite of pulmonary complications after surgery. We assessed the association between cannabis use and opioid consumption during the first 24 postoperative hours using linear regression on log-transformed opioid consumption with a propensity score-based method (inverse probability of treatment weighting [IPTW]) adjusting for confounders. We further adjusted for imbalanced confounding variables after IPTW was applied.

RESULTS

In total, 1683 of 34,521 patients were identified as cannabis users. Cannabis use was associated with increased opioid consumption, with an adjusted ratio of geometric means (95% confidence interval [CI]) of 1.30 (1.22-1.38; P < .0001) for cannabis users versus nonusers. Secondarily, (1) cannabis use was associated with increased TWA pain score, with a difference in means of 0.57 (95% CI, 0.46-0.67; P < .0001); (2) cannabis use was not associated with TWA Spo2/Fio2, with an adjusted difference in means of 0.5 (95% CI, -3.1 to 4.2; P = .76); and (3) cannabis use was not associated with a collapsed composite of pulmonary complications, with estimated odds ratio of 0.90 (95% CI, 0.71-1.13; P = .34).

CONCLUSIONS

Adult cannabis users undergoing surgeries were found to have significantly higher postoperative opioid consumption and pain scores than nonusers. Cannabis use did not have a clinically meaningful association with hypoxia or composite pulmonary complications.

Association between postoperative hypotension and acute kidney injury after noncardiac surgery: a historical cohort analysis

PURPOSE

The extent to which postoperative hypotension contributes to renal injury remains unclear, much less what the harm thresholds might be. We therefore tested the primary hypothesis that there is an absolute hypotensive arterial pressure threshold for acute kidney injury during the initial seven days after noncardiac surgery.

METHODS

We conducted a single-centre historical cohort analysis of adults who had noncardiac surgery and had creatinine recorded preoperatively and postoperatively. Our exposure was the lowest postoperative mean arterial pressure, defined as the average of the three lowest postoperative pressure measurements. Our primary analysis was the association between the lowest mean arterial pressure and acute kidney injury, defined according to Kidney Disease: Improving Global Outcomes initiative criteria. Our analysis was adjusted for potentially relevant confounding factors including intraoperative hypotension.

RESULTS

Among 64,349 patients analyzed, 2,812 (4.4%) patients had postoperative acute kidney injury. Each 5-mm Hg decrease in the lowest mean arterial pressure was associated with a 28% (97.5% confidence interval [CI], 23 to 32; P < 0.001) increase in the odds of acute kidney injury for lowest mean arterial pressures < 80 mm Hg. Higher lowest pressures were not associated with acute kidney injury (odds ratio, 1.08; 97.5% CI, 0.99 to 1.17; P = 0.04) for each 5-mm Hg decrease in the lowest mean arterial pressure.

CONCLUSION

Postoperative hypotension, defined as the lowest postoperative mean arterial pressure < 80 mm Hg, was associated with acute kidney injury after noncardiac surgery. A prospective trial will be required to determine whether the observed association is causal and thus amenable to modification.

Systematic reviews and meta-analyses in regional anesthesia and pain medicine (Part I): guidelines for preparing the review protocol

Comprehensive resources exist on how to plan a systematic review and meta-analysis. The objective of this article is to provide guidance to authors preparing their systematic review protocol in the fields of regional anesthesia and pain medicine. The focus is on systematic reviews of healthcare interventions, with or without an aggregate data meta-analysis. We describe and discuss elements of the systematic review methodology that review authors should prespecify, plan, and document in their protocol before commencing the review. Importantly, authors should explain their rationale for planning their systematic review and describe the PICO framework-participants (P), interventions (I),comparators (C), outcomes (O)-and related elements central to constructing their clinical question, framing an informative review title, determining the scope of the review, designing the search strategy, specifying the eligibility criteria, and identifying potential sources of heterogeneity. We highlight the importance of authors defining and prioritizing the primary outcome, defining eligibility criteria for selecting studies, and documenting sources of information and search strategies. The review protocol should also document methods used to evaluate risk of bias, quality (certainty) of the evidence, and heterogeneity of results. Furthermore, the authors should describe their plans for managing key data elements, the statistical construct used to estimate the intervention effect, methods of evidence synthesis and meta-analysis, and conditions when meta-analysis may not be possible, including the provision of practical solutions. Authors should provide enough detail in their protocol so that the readers could conduct the study themselves.

Systematic reviews and meta-analyses in regional anesthesia and pain medicine (Part II): guidelines for performing the systematic review

In Part I of this series, we provide guidance for preparing a systematic review protocol. In this article, we highlight important steps and supplement with exemplars on conducting and reporting the results of a systematic review. We suggest how authors can manage protocol violations, multiplicity of outcomes and analyses, and heterogeneity. The quality (certainty) of the evidence and strength of recommendations should follow the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach. It is our goal that Part II of this series provides valid guidance to authors and peer reviewers who conduct systematic reviews to adhere to important constructs of transparency, structure, reproducibility, and accountability. This will likely result in more rigorous systematic reviews being submitted for publication to the journals like Regional Anesthesia & Pain Medicine and Anesthesia & Analgesia.

Early detection of deterioration in COVID-19 patients by continuous ward respiratory rate monitoring: a pilot prospective cohort study

Background

Tachypnea is among the earliest signs of pulmonary decompensation. Contactless continuous respiratory rate monitoring might be useful in isolated COVID-19 patients admitted in wards. We therefore aimed to determine whether continuous monitoring of respiratory patterns in hospitalized patients with COVID-19 predicts subsequent need for increased respiratory support.

Methods

Single-center pilot prospective cohort study in COVID-19 patients who were cared for in routine wards. COVID-19 patients who had at least one escalation of pulmonary management were matched to three non-escalated patients. Contactless respiratory monitoring was instituted after patients enrolled, and continued for 15 days unless hospital discharge, initiation of invasive mechanical ventilation, or death occurred. Clinicians were blinded to respiratory rate data from the continuous monitor. The exposures were respiratory features over rolling periods of 30 min, 24 h, and 72 h before respiratory care escalation. The primary outcome was a subsequent escalation in ventilatory support beyond a Venturi mask.

Results

Among 125 included patients, 13 exhibited at least one escalation and were each matched to three non-escalated patients. A total of 28 escalation events were matched to 84 non-escalation episodes. The 30-min mean respiratory rate in escalated patients was 23 breaths per minute (bpm) ranging from 13 to 40 bpm, similar to the 22 bpm in non-escalated patients, although with less variability (range 14 to 31 bpm). However, higher respiratory rate variability, especially skewness over 1 day, was associated with higher incidence of escalation events. Our overall model, based on continuous data, had a moderate accuracy with an AUC 0.81 (95%CI: 0.73, 0.88) and a good specificity 0.93 (95%CI: 0.87, 0.99).

Conclusion

Our pilot observational study suggests that respiratory rate variability as detected with continuous monitoring is associated with subsequent care escalation during the following 24 h. Continuous respiratory monitoring thus appears to be a valuable increment over intermittent monitoring.

Strengths and limitations

Our study was the initial evaluation of Circadia contactless respiratory monitoring in COVID-19 patients who are at special risk of pulmonary deterioration. The major limitation is that the analysis was largely post hoc and thus needs to be confirmed in an out-of-sample population.

Using Preanesthesia Clinic Visits to Improve Advance Directives Completion: An Interrupted Time Series Analysis

BACKGROUND

Advance directives documentation can increase the likelihood that patient's wishes are respected if they become incapacitated. Unfortunately, completion rates are suboptimal overall, and disparities may exist, especially for vulnerable groups. We assessed whether implementing an initiative to standardize advance directives discussions during preanesthesia visits was associated with changes in rates of advance directives completion over time, and whether the association depends on race, insurance type, or income.

METHODS

We conducted a before-after interrupted time series evaluation between January 1, 2015 and June 30, 2019 in a single-center, outpatient preanesthesia clinic. Participants were adults who visited the preanesthesia clinic at Cleveland Clinic and had >1 comorbidity before a noncardiac surgery of either medium or high risk. The intervention in March of 2017 consisted of training staff to help patients complete and witness advance directives documents during visits. We measured advance directives completion, by race, payor, and income (using the 2019 Federal Poverty Line). We assessed the confounder-adjusted association between intervention (pre versus post) and proportion of patients completing advanced directives over time using segmented regression to compare slopes between periods and assess changes at start of the intervention. We used similar models to assess whether changes depended on race, insurance type, or income level.

RESULTS

We included 26,368 visits from 22,430 patients. We analyzed financial status for 16,788 visits from 14,274 patients who had address data. There were 11,242 (43%) visits preintervention and 15,126 (57%) visits postintervention. Crude completion rates for advance directives increased from 29% to 78%, with odds of completion an estimated 18 times higher than preintervention (odds ratio [95% CI] of 18 [16-21]; P < 0.001). Regarding race, Black patients had lower completion rates preintervention than White patients, although the gap steadily closed after the intervention ( P = .001). Postintervention, both race groups immediately increased, with no difference in amount of increase ( P = .17) or postintervention change in slope difference ( P = .17). Regarding insurance, patients with Medicaid had lower preintervention completion rates than those with private. Intervention was associated with increases in both groups, but the difference in slopes ( P = .43) or proportions ( P = .23) between the groups did not change after intervention. Regarding the Federal Poverty Line, the completion rate gap between those below (<100%) and above (139%-400%) narrowed by approximately half (0.51: 95% CI, 0.27-0.98; P = .04).

CONCLUSIONS

Standardizing advance directives discussions during preanesthesia visits was associated with more patients completing advance directives, particularly in vulnerable patient groups.

Best Practice Alerts Informed by Inpatient Opioid Intake to Reduce Opioid Prescribing after Surgery (PRIOR): A Cluster Randomized Multiple Crossover Trial

BACKGROUND

Overprescription of opioids after surgery remains common. Residual and unnecessarily prescribed opioids can provide a reservoir for nonmedical use. This study therefore tested the hypothesis that a decision-support tool embedded in electronic health records guides clinicians to prescribe fewer opioids at discharge after inpatient surgery.

METHODS

This study included 21,689 surgical inpatient discharges in a cluster randomized multiple crossover trial from July 2020 to June 2021 in four Colorado hospitals. Hospital-level clusters were randomized to alternating 8-week periods during which an electronic decision-support tool recommended tailored discharge opioid prescriptions based on previous inpatient opioid intake. During active alert periods, the alert was displayed to clinicians when the proposed opioid prescription exceeded recommended amounts. No alerts were displayed during inactive periods. Carryover effects were mitigated by including 4-week washout periods. The primary outcome was oral morphine milligram equivalents prescribed at discharge. Secondary outcomes included combination opioid and nonopioid prescriptions and additional opioid prescriptions until day 28 after discharge. A vigorous state-wide opioid education and awareness campaign was in place during the trial.

RESULTS

The total postdischarge opioid prescription was a median [quartile 1, quartile 3] of 75 [0, 225] oral morphine milligram equivalents among 11,003 patients discharged when the alerts were active and 100 [0, 225] morphine milligram equivalents in 10,686 patients when the alerts were inactive, with an estimated ratio of geometric means of 0.95 (95% CI, 0.80 to 1.13; P = 0.586). The alert was displayed in 28% (3,074 of 11,003) of the discharges during the active alert period. There was no relationship between the alert and prescribed opioid and nonopioid combination medications or additional opioid prescriptions written after discharge.

CONCLUSIONS

A decision-support tool incorporated into electronic medical records did not reduce discharge opioid prescribing for postoperative patients in the context of vigorous opioid education and awareness efforts. Opioid prescribing alerts might yet be valuable in other contexts.(Anesthesiology 2023; 139:186-96).

EDITOR’S PERSPECTIVE

Processing speed test and 30-day readmission in elderly non-cardiac surgery patients- A retrospective study

Background and Aims

Preoperative cognitive function screening can help identify high-risk patients, but resource-intensive testing limits its widespread use. A novel self-administered tablet computer-based Processing Speed Test (PST) was used to assess cognitive "executive" function in non-cardiac surgery patients, but the relationship between preoperative test scores and postoperative outcomes is unclear. The primary outcome was a composite of 30-day readmission/death. The secondary outcome was a collapsed composite of discharge to a long-term care facility/death. Exploratory outcomes were 1) time to discharge alive, 2) 1-year mortality and 3) a collapsed composite of postoperative complications.

Methods

This retrospective study, after approval, was conducted in elective non-cardiac surgery patients ≥65 years old. We assessed the relationship between processing speed test scores and primary/secondary outcomes using multivariable logistic regression, adjusting for potential confounding variables.

Results

Overall 1568 patients completed the PST, and the mean ± standard deviation test score was 33 ± 10. The higher PST score is associated with better executive function. A 10-unit increase in the test score was associated with an estimated 19% lower 30-day readmission/death odds, with an odds ratio (OR) and 95% confidence interval (CI) of 0.81 (0.68, 0.96) (P = 0.015). Similarly, 10-unit increase in test score was associated with an estimated 26% lower odds of long-term care need/death, with OR (95% CI) of 0.74 (0.61, 0.91) (P = 0.004). We also found statistically significant associations between the test scores and time to discharge alive and to 1-year mortality, however, not with a composite of postoperative complications.

Conclusion

Elderly non-cardiac surgery patients with better PST scores were less likely to be readmitted, need long-term care after discharge or die within 30 days. Preoperative assessment of cognitive function using a simple self-administered test is feasible and may guide perioperative care.

Cooling vest improves surgeons' thermal comfort without affecting cognitive performance: a randomised cross-over trial

OBJECTIVES

Surgeons become uncomfortable while performing surgery because heat transfer and evaporative cooling are restricted by insulating surgical gowns. Consequently, perceptions of thermal discomfort during surgery may impair cognitive performance. We, therefore, aimed to evaluate surgeons' thermal comfort, cognitive performance, core and mean skin temperatures, perceptions of sweat-soaked clothing, fatigue and exertion with and without a CoolSource cooling vest (Cardinal Health, Dublin, Ohio, USA).

METHODS

Thirty orthopaedic surgeons participated in a randomised cross-over trial, each performing four total-joint arthroplasties with randomisation to one of four treatment sequences. The effects of cooling versus no cooling were measured using a repeated-measures linear model accounting for within-subject correlations.

RESULTS

The cooling vest improved thermal comfort by a mean (95% CI) of -2.1 (-2.7 to -1.6) points on a 0-10 scale, p<0.001, with no evidence of treatment-by-period interaction (p=0.94). In contrast, cooling had no perceptible effect on cognition, with an estimated mean difference (95% CI) in Cleveland Clinic Cognitive Battery (C3B) Processing Speed Test score of 0.03 (95% CI -2.44 to 2.51), p=0.98, or in C3B Visual Memory Test score with difference of 0.88 (95% CI -2.25 to 4.01), p=0.57. Core temperature was not lower with the cooling vest, with mean difference (95% CI) of -0.13 (-0.33°C to 0.07°C), p=0.19, while mean skin temperature was lower, with mean difference of -0.23 (95% CI -0.40°C to -0.06°C) lower, p=0.011. The cooling vest significantly reduced surgeons' perceptions of sweat-soaked clothing, fatigue and exertion.

CONCLUSIONS

A cooling vest worn during surgery lowered core and skin temperatures, improved thermal comfort, and decreased perceptions of sweating and fatigue, but did not improve cognition. Thermal discomfort during major orthopaedic surgery is thus largely preventable, but cooling does not affect cognition.

TRIAL REGISTRATION NUMBER

NCT04511208.

Wearable device for prevention of postoperative and post-discharge hypoxemia: A randomized pilot trial

BACKGROUND

The Oxalert Enhanced Pulse Oximeter (EPO) is a wearable device that detects and alerts patients to hypoxemia. In a preplanned pilot trial, we estimated the effect of continuous saturation monitoring with patient alerts on in-hospital and post-discharge saturation; we further assessed the feasibility of the intervention.

METHODS

Noncardiac surgical patients were randomized to either the Oxalert with patient alerts (Monitor + Alert, N = 25) or the Oxalert without patient alerts (Monitor Only, N = 24). Monitoring continued during hospitalization for up to 6 days and for 24 h after hospital discharge. Patients in each group were compared on time-weighted average (TWA) SpO2 <90% (%) and area under SpO2 <90% (% * min) in-hospital and after discharge using the Wilcoxon rank sum test, with the treatment effect median difference and 95% confidence interval (CI) estimated using the Hodges-Lehmann estimator of location shift.

RESULTS

We enrolled ≥2 patients per week, for a total of 49 patients in whom recording were obtained for a median [quartiles] of 91 [85, 95]% of the time in hospital. In-hospital, TWA SpO2 <90% was a median [quartiles] of 0.11 [0.03, 0.25]% for Monitor + Alert and 0.29 [0.04, 0.71]% for Monitor-Only patients, with estimated median difference (95% CI) of -0.1 (-0.4, 0)%, p = .120. In hospital, the area under the curve (AUC) SpO2 <90% was a median [quartiles] of 635 [204, 1513] % * min for Monitor + Alert and 1260 [117, 5278] % * min for Monitor-Only patients, with estimated median difference (95% CI) of -407 (-1816, 208) % * min, p = .349. Post-discharge, the estimated median difference (95% CI) was only -0.1 (-0.2, 0) %, p = .307.

CONCLUSIONS

The Oxalert system was well tolerated in both groups and enrollment was strong. Patients randomized to active Oxalert systems experienced half as many postoperative desaturation events while hospitalized, although the difference was not statistically significant in this small pilot trial. In contrast, the Oxalert system did not reduce post-discharge desaturation. Detecting postoperative deterioation in surgical patients after they arrive on regular hospital wards, and even after they have been discharged home, can potentially facilitate necessary "rescue" interventions. Wearable devices assessing vital signs, including oxygenation, are a practical requirement. In this pilot study, a wearable pulse oximeter, with and without hypoxemia alarms, was tested for feasibility and acceptability for signal collection in postoperative cases, including at home. Results indicate that a full-scale trial is warranted to test for possible clinical benefit with this type of "wearable" where late postoperative hypoxia could be a concern. The trial was registered at ClincialTrial.gov (NCT04453722).

Nociception Level Index-Guided Intraoperative Analgesia for Improved Postoperative Recovery: A Randomized Trial

BACKGROUND

Nociception is the physiological response to nociceptive stimuli, normally experienced as pain. During general anesthesia, patients experience and respond to nociceptive stimuli by increasing blood pressure and heart rate if not controlled by preemptive analgesia. The PMD-200 system from Medasense (Ramat Gan, Israel) evaluates the balance between nociceptive stimuli and analgesia during general anesthesia and generates the nociception level (NOL) index from a single finger probe. NOL is a unitless index ranging from 0 to 100, with values exceeding 25 indicating that nociception exceeds analgesia. We aimed to demonstrate that titrating intraoperative opioid administration to keep NOL <25 optimizes intraoperative opioid dosing. Specifically, we tested the hypothesis that pain scores during the initial 60 minutes of recovery are lower in patients managed with NOL-guided fentanyl than in patients given fentanyl per clinical routine.

METHODS

We conducted a randomized, single-center trial of patients having major abdominal open and laparoscopic surgeries. Patients were randomly assigned 1:1 to intraoperative NOL-guided fentanyl administration or fentanyl given per clinical routine. The primary outcome was pain score (0-10 verbal response scale) at 10-minute intervals during the initial 60 minutes of recovery. Our secondary outcome was a measure of adequate analgesia, defined as a pain score <5, assessed separately at each interval.

RESULTS

With a planned maximum sample size of 144, the study was stopped for futility after enrolling 72 patients from November 2020 to October 2021. Thirty-five patients were assigned to NOL-guided analgesic dosing and 37 to routine care. Patients in the NOL group spent significantly less time with a NOL index >25 (median reduction [95% confidence interval {CI}] of 14 [4-25] minutes) were given nearly twice as much intraoperative fentanyl (median [quartiles] 500 [330, 780] vs 300 [200, 330] µg), and required about half as much morphine in the recovery period (3.3 [0, 8] vs 7.7 [0, 13] mg). However, in the primary outcome analysis, NOL did not reduce pain scores in the first 60 minutes after awakening, assessed in a linear mixed effects model with mean (standard error [SE]) of 4.12 (0.59) for NOL and 4.04 (0.58) for routine care, and estimated difference in means of 0.08 (-1.43, 1.58), P = .895.

CONCLUSIONS

More intraoperative fentanyl was given in NOL-guided patients, but NOL guidance did not reduce initial postoperative pain scores.

Derivation and Validation of Clinical Phenotypes of the Cardiopulmonary Bypass-Induced Inflammatory Response

BACKGROUND

Precision medicine aims to change treatment from a "one-size-fits-all" approach to customized therapies based on the individual patient. Applying a precision medicine approach to a heterogeneous condition, such as the cardiopulmonary bypass (CPB)-induced inflammatory response, first requires identification of homogeneous subgroups that correlate with biological markers and postoperative outcomes. As a first step, we derived clinical phenotypes of the CPB-induced inflammatory response by identifying patterns in perioperative clinical variables using machine learning and simulation tools. We then evaluated whether these phenotypes were associated with biological response variables and clinical outcomes.

METHODS

This single-center, retrospective cohort study used Cleveland Clinic registry data from patients undergoing cardiac surgery with CPB from January 2010 to March 2020. Biomarker data from a subgroup of patients enrolled in a clinical trial were also included. Patients undergoing emergent surgery, off-pump surgery, transplantation, descending thoracoabdominal aortic surgery, and planned ventricular assist device placement were excluded. Preoperative and intraoperative variables of patient baseline characteristics (demographics, comorbidities, and laboratory data) and perioperative data (procedural data, CPB duration, and hemodynamics) were analyzed to derive clinical phenotypes using K-means-based consensus clustering analysis. Proportion of ambiguously clustered was used to assess cluster size and optimal cluster numbers. After clusters were formed, we summarized perioperative profiles, inflammatory biomarkers (eg, interleukin [IL]-6 and IL-8), kidney biomarkers (eg, urine neutrophil gelatinase-associated lipocalin [NGAL] and IL-18), and clinical outcomes (eg, mortality and hospital length of stay). Pairwise standardized difference was reported for all summarized variables.

RESULTS

Of 36,865 eligible cardiac surgery cases, 25,613 met inclusion criteria. Cluster analysis derived 3 clinical phenotypes: α, β, and γ. Phenotype α (n = 6157 [24%]) included older patients with more comorbidities, including heart and kidney failure. Phenotype β (n = 10,572 [41%]) patients were younger and mostly male. Phenotype γ (n = 8884 [35%]) patients were 58% female and had lower body mass index (BMI). Phenotype α patients had worse outcomes, including longer hospital length of stay (mean = 9 days for α versus 6 for both β [absolute standardized difference {ASD} = 1.15] and γ [ASD = 1.08]), more kidney failure, and higher mortality. Inflammatory biomarkers (IL-6 and IL-8) and kidney injury biomarkers (urine NGAL and IL-18) were higher with the α phenotype compared to β and γ immediately after surgery.

CONCLUSIONS

Deriving clinical phenotypes that correlate with response biomarkers and outcomes represents an initial step toward a precision medicine approach for the management of CPB-induced inflammatory response and lays the groundwork for future investigation, including an evaluation of the heterogeneity of treatment effect.

Ultrasound-guided Percutaneous Cryoneurolysis to Treat Chronic Postamputation Phantom Limb Pain: A Multicenter Randomized Controlled Trial

BACKGROUND

Postamputation phantom pain is notoriously persistent with few validated treatments. Cryoneurolysis involves the application of low temperatures to reversibly ablate peripheral nerves. The authors tested the hypothesis that a single cryoneurolysis treatment would decrease phantom pain 4 months later.

METHODS

The authors enrolled patients with a lower-limb amputation and established phantom pain. Each received a single-injection femoral and sciatic nerve block with lidocaine and was subsequently randomized to receive either ultrasound-guided percutaneous cryoneurolysis or sham treatment at these same locations. The primary outcome was the change in average phantom pain intensity between baseline and 4 months as measured with a numeric rating scale (0 to 10), after which an optional crossover treatment was offered. Investigators, participants, and clinical staff were masked to treatment group assignment with the exception of the treating physician performing the cryoneurolysis, who had no subsequent participant interaction.

RESULTS

Pretreatment phantom pain scores were similar in both groups, with a median [quartiles] of 5.0 [4.0, 6.0] for active treatment and 5.0 [4.0, 7.0] for sham. After 4 months, pain intensity decreased by 0.5 [-0.5, 3.0] in patients given cryoneurolysis (n = 71) versus 0 [0, 3] in patients given sham (n = 73), with an estimated difference (95% CI) of -0.1 (-1.0 to 0.7), P = 0.759. Following their statistical gatekeeping protocol, the authors did not make inferences or draw conclusions on secondary endpoints. One serious adverse event occurred after a protocol deviation in which a femoral nerve cryolesion was induced just below the inguinal ligament-instead of the sensory-only saphenous nerve-which resulted in quadriceps weakness, and possibly a fall and clavicle fracture.

CONCLUSIONS

Percutaneous cryoneurolysis did not decrease chronic lower extremity phantom limb pain 4 months after treatment. However, these results were based upon the authors' specific study protocol, and since the optimal cryoneurolysis treatment parameters such as freeze duration and anatomic treatment location remain unknown, further research is warranted.

EDITOR’S PERSPECTIVE

Incidence of sedation-related adverse events during ERCP with anesthesia assistance: a multicenter observational study

BACKGROUND AND AIMS

Anesthesia assistance is commonly used for ERCP. General anesthesia (GA) may provide greater airway protection but may lead to hypotension. We aimed to compare GA versus sedation without planned intubation (SWPI) on the incidence of hypoxemia and hypotension. We also explored risk factors for conversion from SWPI to GA.

METHODS

This observational study used data from the Multicenter Perioperative Outcomes Group. Adults with American Society of Anesthesiologists physical status class I to IV undergoing ERCP between 2006 and 2019 were included. We compared GA and SWPI on incidence of hypoxemia (oxygen saturation <90% for ≥3 minutes) and hypotension (mean arterial pressure <65 mm Hg for ≥5 minutes) using joint hypothesis testing. The association between anesthetic approach and outcomes was assessed using logistic regression. The noninferiority delta for hypoxemia and hypotension was an odds ratio of 1.20. One approach was deemed better if it was noninferior on both outcomes and superior on at least 1 outcome. To explore risk factors associated with conversion from SWPI to GA, we constructed a logistic regression model.

RESULTS

Among 61,735 cases from 42 institutions, 38,830 (63%) received GA and 22,905 (37%) received SWPI. The GA group had 1.27 times (97.5% confidence interval, 1.19-1.35) higher odds of hypotension but .71 times (97.5% confidence interval, .63-.80) lower odds of hypoxemia. Neither group was noninferior to the other on both outcomes. Conversion from SWPI to GA occurred in 6.5% of cases and was associated with baseline comorbidities and higher institutional procedure volume.

CONCLUSIONS

GA for ERCP was associated with less hypoxemia, whereas SWPI was associated with less hypotension. Neither approach was better on the combined incidence of hypotension and hypoxemia.

Intra-operative hypertension and myocardial injury and/or mortality and acute kidney injury after noncardiac surgery: A retrospective cohort analysis

BACKGROUND

Whether intra-operative hypertension causes postoperative complications remains unclear.

OBJECTIVE

We sought to assess whether there is an absolute systolic hypertensive threshold associated with increased odds of a composite of postoperative myocardial injury and mortality, and acute kidney injury.

DESIGN

A retrospective cohort analysis using an electronic medical record registry.

SETTING

The Cleveland Clinic Main Campus, Cleveland, Ohio, USA, between January 2005 and December 2018.

PATIENTS

A total of 76 042 adults who had inpatient noncardiac surgery lasting at least an hour, creatinine recorded preoperatively and postoperatively, and had an available clinic blood pressure within 6 months before surgery.

MAIN OUTCOME MEASURES

Univariable smoothing and multivariable logistic regression were used to estimate the probability of each outcome as a function of the highest intra-operative pressure for a cumulative 5, 10, or 30 min. We further assessed whether the relationships between intra-operative hypertension and each outcome depended on baseline systolic blood pressure.

RESULTS

The composite of myocardial injury and mortality was observed in 1.9%, and acute kidney injury in 4.5% of patients. After adjustment for confounders, there was little or no relationship between systolic pressure and either outcome over the range from 120 to 200 mmHg. There were also no obvious change points or thresholds above which odds of each outcome increased. And finally, there was no interaction with preoperative clinic blood pressure.

CONCLUSIONS

There was no clinically meaningful relationship between intra-operative systolic pressure and the composite of myocardial injury and mortality, or acute kidney injury, over the range from 120 and 200 mmHg.

Procedure-Specific Relationships Between Postoperative Troponin T and a Composite of Mortality and Low Cardiac Output Syndrome: A Retrospective Cohort Analysis

BACKGROUND

Myocardial injury after coronary artery bypass grafting (CABG) is defined as troponin concentrations >10 times 99th percentile upper reference limit (URL) according to the Fourth Universal Definition. However, troponin concentrations after non-CABG cardiac surgery which indicate greater-than-expected myocardial injury and increased risk for complications remain unclear. Our goal was to assess procedure-specific relationships between troponin T and a composite outcome of low cardiac output syndrome and in-hospital mortality in cardiac surgical patients.

METHODS

Patients having cardiac surgery between January 2010 and December 2017 were categorized into 4 groups by procedure: (1) CABG; (2) mitral valve repair; (3) aortic valve repair/replacement (AVR); (4) mitral valve replacement (MVR) or CABG + valve surgeries. Exclusion criteria were elevated preoperative troponin T, preoperative kidney failure, circulatory arrest, or preoperative/planned mechanical circulatory support. Logistic regression was used to assess the association between troponin T and composite outcome, both overall and by procedure, including assessment of the interaction between procedure and troponin T on outcome.

RESULTS

Among 10,253 patients, 37 (0.4%) died and 393 (3.8%) developed the primary outcome. Troponin T concentrations differed by procedure (P < .001). Compared to CABG, AVR had 0.53 (99.2% confidence interval [CI], 0.50-0.56; unadjusted P < .001) times lower troponin T concentrations, while MVR/CABG + valve were 1.54 (99.2% CI, 1.45-1.62, unadjusted P < .001) times higher. There were linear relationships between log2 troponin T concentration and log odds mortality/low cardiac output syndrome. The (unadjusted) relationships were parallel for various types of surgery (interaction P = .59), but at different levels of the outcome.

CONCLUSIONS

The relative increase in odds for mortality/low cardiac output syndrome per a similar increase in troponin T concentrations did not differ among cardiac surgical procedures, but the absolute troponin T concentrations did. Troponin concentrations should thus be interpreted in context of surgical procedure.

Delays to essential surgery at four faith based hospitals in rural Sub-Saharan Africa

BACKGROUND

Data regarding delays for emergency surgery in Sub-Saharan Africa is limited. We have therefore decided to undertake an evaluation of delays in patients seeking care, reaching care and receiving care for emergency surgery at four rural faith-based hospitals in this region over a 3 month period.

METHODS

This is a cross-sectional, multi-center, international study at four rural faith-based hospitals in Madagascar, Gabon, Cameroon and Burundi. All patients presenting at these hospitals between 10 February and 1 May 2020 for one of the three Bellwether procedures (caesarean delivery, emergency laparotomy, management of open fracture) were to be enrolled in this study. Data was collected in the form of a questionnaire administered to the patient or the patient's caregiver within 24 h of admission to the hospital.

RESULTS

After analysis of data for 148 patients, we found that the median [quartiles] delay in seeking care overall was 3.5 [0.5, 17.6] h, in reaching care 7.6 [2.3, 33.6] h and in receiving care 3.6 [1.7, 6.8] h. In 72% (107/148) of cases, the second delay was more than 2 h. Sixty-five percent of patients who were delayed reported that their delay was because care was sought elsewhere before arrival at one of our Bellwether-capable sites.

CONCLUSIONS

Our results suggest that the majority of patients needing emergency surgical care in the rural areas of Sub-Saharan Africa where our study was conducted are frequently delayed, with the largest delay being in reaching care. Further investigations into the reasons for these delays should be conducted.

Statistics From A (Agreement) to Z (z Score): A Guide to Interpreting Common Measures of Association, Agreement, Diagnostic Accuracy, Effect Size, Heterogeneity, and Reliability in Medical Research

Researchers reporting results of statistical analyses, as well as readers of manuscripts reporting original research, often seek guidance on how numeric results can be practically and meaningfully interpreted. With this article, we aim to provide benchmarks for cutoff or cut-point values and to suggest plain-language interpretations for a number of commonly used statistical measures of association, agreement, diagnostic accuracy, effect size, heterogeneity, and reliability in medical research. Specifically, we discuss correlation coefficients, Cronbach's alpha, I2, intraclass correlation (ICC), Cohen's and Fleiss' kappa statistics, the area under the receiver operating characteristic curve (AUROC, concordance statistic), standardized mean differences (Cohen's d, Hedge's g, Glass' delta), and z scores. We base these cutoff values on what has been previously proposed by experts in the field in peer-reviewed literature and textbooks, as well as online statistical resources. We integrate, adapt, and/or expand previous suggestions in attempts to (a) achieve a compromise between divergent recommendations, and (b) propose cutoffs that we perceive sensible for the field of anesthesia and related specialties. While our suggestions provide guidance on how the results of statistical tests are typically interpreted, this does not mean that the results can universally be interpreted as suggested here. We discuss the well-known inherent limitations of using cutoff values to categorize continuous measures. We further emphasize that cutoff values may depend on the specific clinical or scientific context. Rule-of-the thumb approaches to the interpretation of statistical measures should therefore be used judiciously.

Oxygen Saturation and Postoperative Mortality in Patients With Acute Ischemic Stroke Treated by Endovascular Thrombectomy

BACKGROUND

Monitored anesthesia care (MAC) and general anesthesia (GA) with endotracheal intubation are the 2 most used techniques for patients with acute ischemic stroke (AIS) undergoing endovascular thrombectomy. We aimed to test the hypothesis that increased arterial oxygen concentration during reperfusion period is a mechanism underlying the association between use of GA (versus MAC) and increased risk of in-hospital mortality.

METHODS

In this retrospective cohort study, data were collected at the Cleveland Clinic between 2013 and 2018. To assess the potential mediation effect of time-weighted average oxygen saturation (Spo2) in first postoperative 48 hours between the association between GA versus MAC and in-hospital mortality, we assessed the association between anesthesia type and post-operative Spo2 tertiles (exposure-mediator relationship) through a cumulative logistic regression model and assessed the association between Spo2 and in-hospital mortality (mediator-outcome relationship) using logistic regression models. Confounding factors were adjusted for using propensity score methods. Both significant exposure-mediator and significant mediator-outcome relationships are needed to suggest potential mediation effect.

RESULTS

Among 358 patients included in the study, 104 (29%) patients received GA and 254 (71%) received MAC, with respective hospital mortality rate of 19% and 5% (unadjusted P value <.001). GA patients were 1.6 (1.2, 2.1) (P < .001) times more likely to have a higher Spo2 tertile as compared to MAC patients. Patients with higher Spo2 tertile had 3.8 (2.1, 6.9) times higher odds of mortality than patients with middle Spo2 tertile, while patients in the lower Spo2 tertile did not have significant higher odds compared to the middle tertile odds ratio (OR) (1.8 [0.9, 3.4]; overall P < .001). The significant exposure-mediator and mediator-outcome relationships suggest that Spo2 may be a mediator of the relationship between anesthetic method and mortality. However, the estimated direct effect of GA versus MAC on mortality (ie, after adjusting for Spo2; OR [95% confidence interval {CI}] of 2.1 [0.9-4.9]) was close to the estimated association ignoring Spo2 (OR [95% CI] of 2.2 [1.0-5.1]), neither statistically significant, suggesting that Spo2 had at most a modest mediator role.

CONCLUSIONS

GA was associated with a higher Spo2 compared to MAC among those treated by endovascular thrombectomy for AIS. Spo2 values that were higher than the middle tertile were associated with higher odds of mortality. However, GA was not significantly associated with higher odds of death. Spo2 at most constituted a modest mediator role in explaining the relationship between GA versus MAC and mortality.

Percutaneous Neuromodulation of the Brachial Plexus and Sciatic Nerve for the Treatment of Acute Pain Following Surgery: Secondary Outcomes From a Multicenter, Randomized, Controlled Pilot Study

OBJECTIVES

We recently reported that percutaneous peripheral nerve stimulation (PNS or "neuromodulation") decreased pain and opioid consumption within the first two weeks following ambulatory surgery. However, the anatomic lead locations were combined for the analysis, and benefits for each location remain unknown. We therefore now report the effects of percutaneous PNS for brachial plexus and sciatic nerve leads separately.

MATERIALS AND METHODS

Before surgery, leads were implanted percutaneously to target the brachial plexus (N = 21) for rotator cuff repair or sciatic nerve (N = 40) for foot/ankle surgery, followed by a single injection of local anesthetic. Postoperatively, subjects were randomized in a double masked fashion to 14 days of electrical stimulation (N = 30) or sham/placebo (N = 31) using an external pulse generator. The primary outcome of interest was opioid consumption and pain scores evaluated jointly. Thus, stimulation was deemed effective if superior on either outcome and at least noninferior on the other.

RESULTS

For brachial plexus leads, during the first seven postoperative days pain measured with the numeric rating scale in participants given active stimulation was a median [interquartile range ] of 0.8 [0.5, 1.6] versus 3.2 [2.7, 3.5] in patients given sham (p < 0.001). For this same group, opioid consumption in participants given active stimulation was 10 mg [5, 20] versus 71 mg [35, 125] in patients given sham (p = 0.043). For sciatic nerve leads, pain scores for the active treatment group were 0.7 [0, 1.4] versus 2.8 [1.6, 4.6] in patients given sham (p < 0.001). During this same period, participants given active stimulation consumed 5 mg [0, 30] of opioids versus 40 mg [20, 105] in patients given sham (p = 0.004). Treatment effects did not differ statistically between the two locations.

CONCLUSIONS

Ambulatory percutaneous PNS of both the brachial plexus and sciatic nerve is an effective treatment for acute pain free of systemic side-effects following painful orthopedic surgery.

Developing a Clinical Prediction Score: Comparing Prediction Accuracy of Integer Scores to Statistical Regression Models

Researchers often convert prediction tools built on statistical regression models into integer scores and risk classification systems in the name of simplicity. However, this workflow discards useful information and reduces prediction accuracy. We, therefore, investigated the impact on prediction accuracy when researchers simplify a regression model into an integer score using a simulation study and an example clinical data set. Simulated independent training and test sets (n = 1000) were randomly generated such that a logistic regression model would perform at a specified target area under the receiver operating characteristic curve (AUC) of 0.7, 0.8, or 0.9. After fitting a logistic regression with continuous covariates to each data set, continuous variables were dichotomized using data-dependent cut points. A logistic regression was refit, and the coefficients were scaled and rounded to create an integer score. A risk classification system was built by stratifying integer scores into low-, intermediate-, and high-risk tertiles. Discrimination and calibration were assessed by calculating the AUC and index of prediction accuracy (IPA) for each model. The optimism in performance between the training set and test set was calculated for both AUC and IPA. The logistic regression model using the continuous form of covariates outperformed all other models. In the simulation study, converting the logistic regression model to an integer score and subsequent risk classification system incurred an average decrease of 0.057-0.094 in AUC, and an absolute 6.2%-17.5% in IPA. The largest decrease in both AUC and IPA occurred in the dichotomization step. The dichotomization and risk stratification steps also increased the optimism of the resulting models, such that they appeared to be able to predict better than they actually would on new data. In the clinical data set, converting the logistic regression with continuous covariates to an integer score incurred a decrease in externally validated AUC of 0.06 and a decrease in externally validated IPA of 13%. Converting a regression model to an integer score decreases model performance considerably. Therefore, we recommend developing a regression model that incorporates all available information to make the most accurate predictions possible, and using the unaltered regression model when making predictions for individual patients. In all cases, researchers should be mindful that they correctly validate the specific model that is intended for clinical use.

Immediate Effects of a Continuous Peripheral Nerve Block on Postamputation Phantom and Residual Limb Pain: Secondary Outcomes From a Multicenter Randomized Controlled Clinical Trial

BACKGROUND

We recently reported that a 6-day continuous peripheral nerve block reduced established postamputation phantom pain 3 weeks after treatment ended. However, the immediate effects of perineural infusion (secondary outcomes) have yet to be reported.

METHODS

Participants from 5 enrolling academic centers with an upper or lower limb amputation and established phantom pain received a single-injection ropivacaine peripheral nerve block(s) and perineural catheter insertion(s). They were subsequently randomized to receive a 6-day ambulatory perineural infusion of either ropivacaine 0.5% or normal saline in a double-masked fashion. Participants were contacted by telephone 1, 7, 14, 21, and 28 days after the infusion started, with pain measured using the Numeric Rating Scale. Treatment effects were assessed using the Wilcoxon rank-sum test at each time point. Adjusting for 4 time points (days 1, 7, 14, and 21), P < .0125 was deemed statistically significant. Significance at 28 days was reported using methods from the original, previously published article.

RESULTS

Pretreatment average phantom and residual pain scores were balanced between the groups. The day after infusion initiation (day 1), average phantom, and residual limb pain intensity was lower in patients receiving local anesthetic (n = 71) versus placebo (n = 73): median [quartiles] of 0 [0-2.5] vs 3.3 [0-5.0], median difference (98.75% confidence interval [CI]) of -1.0 (-3.0 to 0) for phantom pain (P = .001) and 0 [0-0] vs 0 [0-4.3], and median difference 0.0 (-2.0 to 0.0) for residual limb pain (P < .001). Pain's interference with physical and emotional functioning as measured with the interference domain of the Brief Pain Inventory improved during the infusion on day 1 for patients receiving local anesthetic versus placebo: 0 [0-10] vs 10 [0-40], median difference (98.75% CI) of 0.0 (-16.0 to 0.0), P = .002. Following infusion discontinuation (day 6), a few differences were found between the active and placebo treatment groups between days 7 and 21. In general, sample medians for average phantom and residual limb pain scores gradually increased after catheter removal for both treatments, but to a greater degree in the control group until day 28, at which time the differences between the groups returned to statistical significance.

CONCLUSIONS

This secondary analysis suggests that a continuous peripheral nerve block decreases phantom and residual limb pain during the infusion, although few improvements were again detected until day 28, 3 weeks following catheter removal.

Ultrasound-Guided Percutaneous Peripheral Nerve Stimulation: A Pragmatic Effectiveness Trial of a Nonpharmacologic Alternative for the Treatment of Postoperative Pain

BACKGROUND

Percutaneous peripheral nerve stimulation (PNS) is an analgesic modality involving the insertion of a lead through an introducer needle followed by the delivery of electric current after needle withdrawal. This modality has been used extensively to treat chronic pain, but only small series have been published involving postoperative pain. The ultimate objective of this study is to determine the postoperative effects of percutaneous PNS following moderately to severely painful ambulatory surgery within a real-world clinical practice setting. The primary hypothesis is that surgical pain and opioid consumption during the initial 7 days after surgery will be reduced by percutaneous PNS compared with usual and customary analgesia (dual primary outcome measures).

DESIGN

A multicenter pragmatic effectiveness trial. We are randomizing participants having painful orthopedic surgical procedures of the upper and lower extremity to receive 14 days of either 1) electrical stimulation or 2) sham in a double-masked fashion. End points are being assessed at various time points over 12 postoperative months.

SUMMARY

The postoperative experience will be much improved if percutaneous PNS provides potent analgesia while concurrently decreasing opioid requirements following painful surgery. Because this modality can be administered for up to 60 days at home, it may provide postoperative analgesia that outlasts surgical pain yet has relatively few risks and, unlike opioids, has no systemic side effects or potential for abuse, addiction, and overdose. Percutaneous PNS has the potential to revolutionize postoperative analgesia as it has been practiced for the past century. This study will inform key stakeholders regarding an evidence-based nonpharmacologic approach to the management of postoperative pain.

Effect of Intravenous Acetaminophen on Mean Arterial Blood Pressure: A Post Hoc Analysis of the EFfect of Intravenous ACetaminophen on PosToperative HypOxemia After Abdominal SurgeRy Trial

BACKGROUND

Acetaminophen is commonly used as part of multimodal analgesia for acute pain. The intravenous formulation offers a more predictable bioavailability compared to oral and rectal acetaminophen. There have been reports of hypotension with intravenous acetaminophen attributable to centrally mediated and vasodilatory effects. We tested the hypothesis that in adults having abdominal surgery the use of intravenous acetaminophen versus placebo for postoperative pain management is associated with a decrease in mean arterial pressure (MAP) after its administration.

METHODS

This is a substudy of eFfect of intravenous ACetaminophen on posToperative hypOxemia after abdominal surgeRy (FACTOR) trial (NCT02156154). FACTOR trial randomly assigned adults undergoing abdominal surgery to either 1 g of acetaminophen or placebo every 6 hours during the first postoperative 48 hours. Continuous monitoring of blood pressure was obtained by noninvasive ViSi Mobile device (Sotera Wireless, Inc, San Diego, CA) at 15-second intervals during initial 48 hours postoperatively. We excluded patients without continuous monitoring data available. The primary outcome was the MAP difference between MAP 5 minutes before study drug administration (baseline) and MAP 30 minutes poststudy drug administration initiation. We used a linear mixed effects model to assess the treatment effect on MAP change. The secondary outcome was MAP area under baseline (AUB) during the 30 minutes after treatment. In a sensitivity analysis of change in MAP from predrug to postdrug administration, we instead used postdrug MAP as the outcome adjusting for the baseline MAP in the model.

RESULTS

Among 358 patients analyzed, 182 received acetaminophen and 176 placebo. The mean (standard deviation [SD]) of average MAP change was -0.75 (5.9) mm Hg for the treatment and 0.32 (6.3) mm Hg for the placebo. Acetaminophen was found to decrease the MAP from baseline more than placebo after drug administration. The estimated difference in mean change of MAP was -1.03 (95% confidence interval [CI] -1.60 to -0.47) mm Hg; P < .001. The sensitivity analysis showed postoperative MAP in the acetaminophen group was 1.33 (95% CI, 0.76-1.90) mm Hg lower than in the placebo group (P < .001). The median of MAP AUB was 33 [Q1 = 3.3, Q3 = 109] mm Hg × minutes for the treatment and 23 [1.6, 79] mm Hg × minutes for the placebo. Acetaminophen was found to increase the AUB with an estimated median difference of 15 (95% CI, 5-25) mm Hg × minutes (P = .003).

CONCLUSIONS

Intravenous acetaminophen decreases MAP after its administration. However, this decrease does not appear to be clinically meaningful. Clinicians should not refrain to use intravenous acetaminophen for acute pain management because of worries of hypotension.

Blood Pressure Management by Anesthesia Professionals: Evaluating Clinician Skill From Electronic Medical Records

BACKGROUND

Avoiding intraoperative hypotension might serve as a measure of clinician skill. We, therefore, estimated the range of hypotension in patients of nurse anesthetists, and whether observed differences were associated with a composite of serious complications.

METHODS

First, we developed a multivariable model to predict the amount of hypotension, defined as minutes of mean arterial pressure (MAP) <65 mm Hg, for noncardiac surgical cases from baseline characteristics excluding nurse anesthetist. Second, we compared observed and predicted amounts of hypotension for each case and summarized "excess" amounts across providers. Third, we estimated the extent to which hypotension on an individual case level was independently associated with a composite of serious complications. Finally, we assessed the range of actual and excess minutes of MAP <65 mm Hg on a provider level, and the extent to which these pressure exposures were associated with complications.

RESULTS

We considered 110,391 hours of anesthesia by 99 nurse anesthetists. A total of 69% of 25,702 included cases had at least 1 minute of MAP <65 mm Hg, with a median (quartiles) of 4 (0-15) minutes on the case level. We were unable to explain much variance of intraoperative hypotension from baseline patient characteristics. However, cases in the highest 2 quartiles (>10 and >24 min/case more than predicted) were an estimated 27% (95% confidence interval [CI], 1.1-1.4) and 31% (95% CI, 1.2-1.5) more likely to experience complications compared to those with 0 excess minutes (both P < .001). There was little variation of the average excess minutes <65 mm Hg across the nurse anesthetists, with median (quartiles) of 1.6 (1.2-1.9) min/h. There was no association in confounder-adjusted models on the nurse anesthetist level between average excess hypotension and complications, either for continuous exposure (P = .09) or as quintiles (P = .30).

CONCLUSIONS

Hypotension is associated with complications on a case basis. But the average amount of hypotension for nurse anesthetists over hundreds of cases differed only slightly and was insufficient to explain meaningful differences in complications. Avoiding hypotension is a worthy clinical goal, but does not appear to be a useful metric of performance because the range of average amounts per clinician is not meaningfully associated with patient outcomes, at least among nurse anesthetists in 1 tertiary center.

Optimal interval and duration of CAM-ICU assessments for delirium detection after cardiac surgery

STUDY OBJECTIVE

Our goal was to determine when postoperative delirium first occurs, and to assess evaluation strategies that reliably detect delirium with lowest frequency of testing'.

DESIGN

This was a retrospective study that used a database from a five-center randomized trial.

SETTING

Postoperative cardiothoracic ICU and surgical wards.

PARTICIPANT

Adults scheduled for elective coronary artery bypass and/or valve surgery.

INTERVENTION AND MEASUREMENTS

Postoperative delirium was assessed using CAM-ICU questionnaires twice daily for 5 days or until hospital discharge. Data were analyzed using frequency tables and Kaplan-Meier time-to-event estimators, the latter being used to summarize time to first positive CAM-ICU over POD1-5 for all patients for various evaluation strategies, including all assessments, only morning assessment, and only afternoon assessments. Sensitivity for various strategies were compared using McNemar's test for paired proportions.

MAIN RESULTS

A total of 95 of 788 patients (12% [95% CI, 10% to 15%]) had at least 1 episode of delirium within the first 5 postoperative days. Among all patients with delirium, 65% were identified by the end of the first postoperative day. Delirium was detected more often in the mornings (10% of patients) than evenings (7% of patients). Compared to delirium assessments twice daily for five days, we found that twice daily assessments for 4 days detected an estimated 97% (95% CI 91%, 99%) of delirium. Measurements twice daily for three days detected 90% (82%, 95%) of delirium.

CONCLUSIONS

Postoperative delirium is common, and CAM-ICU assessments twice daily for 4 days, versus 5 days, detects nearly all delirium with 20% fewer assessments. Four days of assessment may usually be sufficient for clinical and research purposes.

Do It Often, Do It Better: Association Between Pairs of Experienced Subspecialty Anesthesia Caregivers and Postoperative Outcomes. A Retrospective Observational Study

BACKGROUND

Anesthesiologists typically care for patients having a broad range of procedures. Outcomes might be improved when care is provided by caregivers experienced in particular types of surgery. We tested the hypothesis that intraoperative care provided by pairs of anesthesia caregivers having significant experience with a particular type of surgery reduces a composite of in-hospital death and 6 serious complications, including bleeding, cardiac, gastrointestinal, infectious, respiratory, and urinary complications, compared to care provided by pairs of anesthesia caregivers with less experience.

METHODS

We included patients having surgery lasting at least 30 minutes. Using cluster analysis, attending anesthesiologists, and Certified Registered Nurse Anesthetists (CRNAs) were identified as experienced or inexperienced caregivers for each type of surgery at the case level. We then compared surgeries for which anesthesia was provided by a pair of experienced caregivers versus a pair of inexperienced caregivers on our composite outcome. We estimated the average relative effect (ie, the exponentiated average log odds ratio) of receiving anesthesia from an experienced versus inexperienced caregiver pair across the 7 components of the composite outcome using a generalized estimating equation (GEE) model to adjust for between-component correlation and with inverse propensity score weighing to adjust for potential confounding from a host of variables.

RESULTS

A total of 8968 patients who received anesthesia care by an experienced pair were compared with 25,361 patients who received care from an inexperienced pair, adjusting for potential confounding. The incidence of composite complications (ie, any component event) was 7.6% (677/8968) for experienced pairs and 12% (2976/25,361) for inexperienced pairs (P < .001). Care by experienced pairs of caregivers was associated with lower odds of the composite outcome with an estimated average relative effect odds ratio across the individual components of 0.61 (95% confidence interval [CI], 0.54-0.71), P < .001. Among the 7 components of the primary outcome, experienced pairs of providers had significantly lower estimated odds of bleeding, infection, and mortality.

CONCLUSIONS

Anesthesia care by experienced pairs was associated with fewer bleeding complications, fewer infections, shorter hospitalization, and reduced in-hospital mortality.

Ambulatory continuous peripheral nerve blocks to treat postamputation phantom limb pain: a multicenter, randomized, quadruple-masked, placebo-controlled clinical trial

Phantom limb pain is thought to be sustained by reentrant neural pathways, which provoke dysfunctional reorganization in the somatosensory cortex. We hypothesized that disrupting reentrant pathways with a 6-day-long continuous peripheral nerve block reduces phantom pain 4 weeks after treatment. We enrolled patients who had an upper- or lower-limb amputation and established phantom pain. Each was randomized to receive a 6-day perineural infusion of either ropivacaine or normal saline. The primary outcome was the average phantom pain severity as measured with a Numeric Rating Scale (0-10) at 4 weeks, after which an optional crossover treatment was offered within the following 0 to 12 weeks. Pretreatment pain scores were similar in both groups, with a median (interquartile range) of 5.0 (4.0, 7.0) for each. After 4 weeks, average phantom limb pain intensity was a mean (SD) of 3.0 (2.9) in patients given local anesthetic vs 4.5 (2.6) in those given placebo (difference [95% confidence interval] 1.3 [0.4, 2.2], P = 0.003). Patients given local anesthetic had improved global impression of change and less pain-induced physical and emotional dysfunction, but did not differ on depression scores. For subjects who received only the first infusion (no self-selected crossover), the median decrease in phantom limb pain at 6 months for treated subjects was 3.0 (0, 5.0) vs 1.5 (0, 5.0) for the placebo group; there seemed to be little residual benefit at 12 months. We conclude that a 6-day continuous peripheral nerve block reduces phantom limb pain as well as physical and emotional dysfunction for at least 1 month.

Mechanisms contributing to hypotension after anesthetic induction with sufentanil, propofol, and rocuronium: a prospective observational study

It remains unclear whether reduced myocardial contractility, venous dilation with decreased venous return, or arterial dilation with reduced systemic vascular resistance contribute most to hypotension after induction of general anesthesia. We sought to assess the relative contribution of various hemodynamic mechanisms to hypotension after induction of general anesthesia with sufentanil, propofol, and rocuronium. In this prospective observational study, we continuously recorded hemodynamic variables during anesthetic induction using a finger-cuff method in 92 non-cardiac surgery patients. After sufentanil administration, there was no clinically important change in arterial pressure, but heart rate increased from baseline by 11 (99.89% confidence interval: 7 to 16) bpm (P < 0.001). After administration of propofol, mean arterial pressure decreased by 23 (17 to 28) mmHg and systemic vascular resistance index decreased by 565 (419 to 712) dyn*s*cm⁻⁵*m² (P values < 0.001). Mean arterial pressure was < 65 mmHg in 27 patients (29%). After propofol administration, heart rate returned to baseline, and stroke volume index and cardiac index remained stable. After tracheal intubation, there were no clinically important differences compared to baseline in heart rate, stroke volume index, and cardiac index, but arterial pressure and systemic vascular resistance index remained markedly decreased. Anesthetic induction with sufentanil, propofol, and rocuronium reduced arterial pressure and systemic vascular resistance index. Heart rate, stroke volume index, and cardiac index remained stable. Post-induction hypotension therefore appears to result from arterial dilation with reduced systemic vascular resistance rather than venous dilation or reduced myocardial contractility.

Arterial Catheters for Early Detection and Treatment of Hypotension During Major Noncardiac Surgery: A Randomized Trial

BACKGROUND

Continuous blood pressure monitoring may facilitate early detection and prompt treatment of hypotension. We tested the hypothesis that area under the curve (AUC) mean arterial pressure (MAP) <65 mm Hg is reduced by continuous invasive arterial pressure monitoring.

METHODS

Adults having noncardiac surgery were randomly assigned to continuous invasive arterial pressure or intermittent oscillometric blood pressure monitoring. Arterial catheter pressures were recorded at 1-minute intervals; oscillometric pressures were typically recorded at 5-minute intervals. We estimated the arterial catheter effect on AUC-MAP <65 mm Hg using a multivariable proportional odds model adjusting for imbalanced baseline variables and duration of surgery. Pressures <65 mm Hg were categorized as 0, 1-17, 18-91, and >91 mm Hg × minutes of AUC-MAP <65 mm Hg (ie, no hypotension and 3 equally sized groups of increasing hypotension).

RESULTS

One hundred fifty-two patients were randomly assigned to arterial catheter use and 154 to oscillometric monitoring. For various clinical reasons, 143 patients received an arterial catheter, while 163 were monitored oscillometrically. There were a median [Q1, Q3] of 246 [187, 308] pressure measurements in patients with arterial catheters versus 55 (46, 75) measurements in patients monitored oscillometrically. In the primary intent-to-treat analysis, catheter-based monitoring increased detection of AUC-MAP <65 mm Hg, with an estimated proportional odds ratio (ie, odds of being in a worse hypotension category) of 1.78 (95% confidence interval [CI], 1.18-2.70; P = .006). The result was robust over an as-treated analysis and for sensitivity analyses with thresholds of 60 and 70 mm Hg.

CONCLUSIONS

Intraoperative blood pressure monitoring with arterial catheters detected nearly twice as much hypotension as oscillometric measurements.

Effect of Intravenous Acetaminophen on Postoperative Hypoxemia After Abdominal Surgery: The FACTOR Randomized Clinical Trial

IMPORTANCE

Opioid-induced ventilatory depression and hypoxemia is common, severe, and often unrecognized in postoperative patients. To the extent that nonopioid analgesics reduce opioid consumption, they may decrease postoperative hypoxemia.

OBJECTIVE

To test the hypothesis that duration of hypoxemia is less in patients given intravenous acetaminophen than those given placebo.

DESIGN, SETTING, AND PARTICIPANTS

Randomized, placebo-controlled, double-blind trial conducted at 2 US academic hospitals among 570 patients who were undergoing abdominal surgery, enrolled from February 2015 through October 2018 and followed up until February 2019.

INTERVENTIONS

Participants were randomized to receive either intravenous acetaminophen, 1 g (n = 289), or normal saline placebo (n = 291) starting at the beginning of surgery and repeated every 6 hours until 48 postoperative hours or hospital discharge, whichever occurred first.

MAIN OUTCOMES AND MEASURES

The primary outcome was the total duration of hypoxemia (hemoglobin oxygen saturation [Spo2] <90%) per hour, with oxygen saturation measured continuously for 48 postoperative hours. Secondary outcomes were postoperative opioid consumption, pain (0- 10-point scale; 0: no pain; 10: the most pain imaginable), nausea and vomiting, sedation, minimal alveolar concentration of volatile anesthetic, fatigue, active time, and respiratory function.

RESULTS

Among 580 patients randomized (mean age, 49 years; 48% women), 570 (98%) completed the trial. The primary outcome, median duration with Spo2 of less than 90%, was 0.7 (interquartile range [IQR], 0.1-5.1) minutes per hour among patients in the acetaminophen group and 1.1 (IQR, 0.1-6.6) minutes per hour among patients in the placebo group (P = .29), with an estimated median difference of -0.04 (95% CI,-0.18 to 0.11) minutes per hour. None of the 8 secondary end points differed significantly between the acetaminophen and placebo groups. Mean pain scores within initial 48 postoperative hours were 4.2 (SD, 1.8) in the acetaminophen group and 4.4 (SD, 1.8) in the placebo group (difference, -0.28; 95% CI, -0.71 to 0.15); median opioid use in morphine equivalents was 50 mg (IQR, 18-122 mg) and 58 mg (IQR, 24-151 mg) , respectively, with a ratio of geometric means of 0.86 (95% CI, 0.61-1.21).

CONCLUSIONS AND RELEVANCE

Among patients who underwent abdominal surgery, use of postoperative intravenous acetaminophen, compared with placebo, did not significantly reduce the duration of postoperative hypoxemia over 48 hours. The study findings do not support the use of intravenous acetaminophen for this purpose.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02156154.

Staffing With Disease-Based Epidemiologic Indices May Reduce Shortage of Intensive Care Unit Staff During the COVID-19 Pandemic

BACKGROUND

Health care worker (HCW) safety is of pivotal importance during a pandemic such as coronavirus disease 2019 (COVID-19), and employee health and well-being ensure functionality of health care institutions. This is particularly true for an intensive care unit (ICU), where highly specialized staff cannot be readily replaced. In the light of lacking evidence for optimal staffing models in a pandemic, we hypothesized that staff shortage can be reduced when staff scheduling takes the epidemiology of a disease into account.

METHODS

Various staffing models were constructed, and comprehensive statistical modeling was performed. A typical routine staffing model was defined that assumed full-time employment (40 h/wk) in a 40-bed ICU with a 2:1 patient-to-staff ratio. A pandemic model assumed that staff worked 12-hour shifts for 7 days every other week. Potential in-hospital staff infections were simulated for a total period of 120 days, with a probability of 10%, 25%, and 40% being infected per week when at work. Simulations included the probability of infection at work for a given week, of fatality after infection, and the quarantine time, if infected.

RESULTS

Pandemic-adjusted staffing significantly reduced workforce shortage, and the effect progressively increased as the probability of infection increased. Maximum effects were observed at week 4 for each infection probability with a 17%, 32%, and 38% staffing reduction for an infection probability of 0.10, 0.25, and 0.40, respectively.

CONCLUSIONS

Staffing along epidemiologic considerations may reduce HCW shortage by leveling the nadir of affected workforce. Although this requires considerable efforts and commitment of staff, it may be essential in an effort to best maintain staff health and operational functionality of health care facilities and systems.

Associations of Intraoperative Radial Arterial Systolic, Diastolic, Mean, and Pulse Pressures with Myocardial and Acute Kidney Injury after Noncardiac Surgery: A Retrospective Cohort Analysis

BACKGROUND

Arterial pressure is a complex signal that can be characterized by systolic, mean, and diastolic components, along with pulse pressure (difference between systolic and diastolic pressures). The authors separately evaluated the strength of associations among intraoperative pressure components with myocardial and kidney injury after noncardiac surgery.

METHODS

The authors included 23,140 noncardiac surgery patients at Cleveland Clinic who had blood pressure recorded at 1-min intervals from radial arterial catheters. The authors used univariable smoothing and multivariable logistic regression to estimate probabilities of each outcome as function of patients' lowest pressure for a cumulative 5 min for each component, comparing discriminative ability using C-statistics. The authors further assessed the association between outcomes and both area and minutes under derived thresholds corresponding to the beginning of increased risk for the average patient.

RESULTS

Out of 23,140 patients analyzed, myocardial injury occurred in 6.1% and acute kidney injury in 8.2%. Based on the lowest patient blood pressure experienced for greater than or equal to 5 min, estimated thresholds below which the odds of myocardial or kidney injury progressively increased (slope P < 0.001) were 90 mmHg for systolic, 65 mmHg for mean, 50 mmHg for diastolic, and 35 mmHg for pulse pressure. Weak discriminative ability was noted between the pressure components, with univariable C-statistics ranging from 0.55 to 0.59. Area under the curve in the highest (deepest) quartile of exposure below the respective thresholds had significantly higher odds of myocardial injury after noncardiac surgery and acute kidney injury compared to no exposure for systolic, mean, and pulse pressure (all P < 0.001), but not diastolic, after adjusting for confounding.

CONCLUSIONS

Systolic, mean, and pulse pressure hypotension were comparable in their strength of association with myocardial and renal injury. In contrast, the relationship with diastolic pressure was poor. Baseline factors were much more strongly associated with myocardial and renal injury than intraoperative blood pressure, but pressure differs in being modifiable.

Recurrence of breast cancer after regional or general anaesthesia: a randomised controlled trial

BACKGROUND

Three perioperative factors impair host defence against recurrence during cancer surgery: the surgical stress response, use of volatile anaesthetic, and opioids for analgesia. All factors are ameliorated by regional anaesthesia-analgesia. We tested the primary hypothesis that breast cancer recurrence after potentially curative surgery is lower with regional anaesthesia-analgesia using paravertebral blocks and the anaesthetic propofol than with general anaesthesia with the volatile anaesthetic sevoflurane and opioid analgesia. A second hypothesis was that regional anaesthesia-analgesia reduces persistent incisional pain.

METHODS

We did a randomised controlled trial at 13 hospitals in Argentina, Austria, China, Germany, Ireland, New Zealand, Singapore, and the USA. Women (age <85 years) having potentially curative primary breast cancer resections were randomised by computer to either regional anaesthesia-analgesia (paravertebral blocks and propofol) or general anaesthesia (sevoflurane) and opioid analgesia. The primary outcome was local or metastatic breast cancer recurrence. The secondary outcome was incisional pain at 6 months and 12 months. Primary analyses were done under intention-to-treat principles. This trial is registered with ClinicalTrials.gov, NCT00418457. The study was stopped after a preplanned futility boundary was crossed.

FINDINGS

Between Jan 30, 2007, and Jan 18, 2018, 2132 women were enrolled to the study, of whom 24 were excluded before surgery. 1043 were assigned to regional anaesthesia-analgesia and 1065 were allocated to general anaesthesia. Baseline characteristics were well balanced between study groups. Median follow-up was 36 (IQR 24-49) months. Among women assigned regional anaesthesia-analgesia, 102 (10%) recurrences were reported, compared with 111 (10%) recurrences among those allocated general anaesthesia (hazard ratio 0·97, 95% CI 0·74-1·28; p=0·84). Incisional pain was reported by 442 (52%) of 856 patients assigned to regional anaesthesia-analgesia and 456 (52%) of 872 patients allocated to general anaesthesia at 6 months, and by 239 (28%) of 854 patients and 232 (27%) of 852 patients, respectively, at 12 months (overall interim-adjusted odds ratio 1·00, 95% CI 0·85-1·17; p=0·99). Neuropathic breast pain did not differ by anaesthetic technique and was reported by 87 (10%) of 859 patients assigned to regional anaesthesia-analgesia and 89 (10%) of 870 patients allocated to general anaesthesia at 6 months, and by 57 (7%) of 857 patients and 57 (7%) of 854 patients, respectively, at 12 months.

INTERPRETATION

In our study population, regional anaesthesia-analgesia (paravertebral block and propofol) did not reduce breast cancer recurrence after potentially curative surgery compared with volatile anaesthesia (sevoflurane) and opioids. The frequency and severity of persistent incisional breast pain was unaffected by anaesthetic technique. Clinicians can use regional or general anaesthesia with respect to breast cancer recurrence and persistent incisional pain.

FUNDING

Sisk Healthcare Foundation (Ireland), Eccles Breast Cancer Research Fund, British Journal of Anaesthesia International, College of Anaesthetists of Ireland, Peking Union Medical College Hospital, Science Fund for Junior Faculty 2016, Central Bank of Austria, and National Healthcare Group.

Effect of red blood cell storage duration on major postoperative complications in cardiac surgery: A randomized trial

BACKGROUND

Although observational studies suggest an association between transfusion of older red blood cell (RBC) units and increased postoperative risk, randomized trials have not supported this. The objective of this randomized trial was to test the effect of RBC storage age on outcomes after cardiac surgery.

METHODS

From July 2007 to May 2016, 3835 adults undergoing coronary artery bypass grafting, cardiac valve procedures, or ascending aorta repair, either alone or in combination, were randomized to transfusion of RBCs stored for ≤14 days (younger units) or for ≥20 days (older units) intraoperatively and throughout the postoperative hospitalization. According to protocol, 2448 patients were excluded because they did not receive RBC transfusions. Among the remaining 1387 modified intent-to-treat patients, 701 were randomized to receive younger RBC units (median age, 11 days) and the remaining 686 to receive older units (median age, 25 days). The primary endpoint was composite morbidity and mortality, analyzed using a generalized estimating equation (GEE) model. The trial was discontinued midway owing to enrollment constraints.

RESULTS

A total of 5470 RBC units were transfused, including 2783 in the younger RBC storage group and 2687 in the older RBC storage group. The GEE average relative-effect odds ratio was 0.77 (95% confidence interval [CI], 0.50-1.19; P = .083) for the composite morbidity and mortality endpoint. In-hospital mortality was lower for the younger RBC storage group (2.1% [n = 15] vs 3.4% [n = 23]), as was occurrence of other adverse events except for atrial fibrillation, although all CIs crossed 1.0.

CONCLUSIONS

This clinical trial, which was stopped at its midpoint owing to enrollment constraints, supports neither the efficacy nor the futility of transfusing either younger or older RBC units. The effects of transfusing RBCs after even more prolonged storage (35-42 days) remains untested.