Complication Rates of Central Venous Catheters: A Systematic Review and Meta-Analysis

Importance

Central venous catheters (CVCs) are commonly used but are associated with complications. Quantifying complication rates is essential for guiding CVC utilization decisions.

Objective

To summarize current rates of CVC-associated complications.

Data Sources

MEDLINE, Embase, CINAHL, and CENTRAL databases were searched for observational studies and randomized clinical trials published between 2015 to 2023.

Study Selection

This study included English-language observational studies and randomized clinical trials of adult patients that reported complication rates of short-term centrally inserted CVCs and data for 1 or more outcomes of interest. Studies that evaluated long-term intravascular devices, focused on dialysis catheters not typically used for medication administration, or studied catheters placed by radiologists were excluded.

Data Extraction and Synthesis

Two reviewers independently extracted data and assessed risk of bias. Bayesian random-effects meta-analysis was applied to summarize event rates. Rates of placement complications (events/1000 catheters with 95% credible interval [CrI]) and use complications (events/1000 catheter-days with 95% CrI) were estimated.

Main Outcomes and Measures

Ten prespecified complications associated with CVC placement (placement failure, arterial puncture, arterial cannulation, pneumothorax, bleeding events requiring action, nerve injury, arteriovenous fistula, cardiac tamponade, arrhythmia, and delay of ≥1 hour in vasopressor administration) and 5 prespecified complications associated with CVC use (malfunction, infection, deep vein thrombosis [DVT], thrombophlebitis, and venous stenosis) were assessed. The composite of 4 serious complications (arterial cannulation, pneumothorax, infection, or DVT) after CVC exposure for 3 days was also assessed.

Results

Of 11 722 screened studies, 130 were included in the analyses. Seven of 15 prespecified complications were meta-analyzed. Placement failure occurred at 20.4 (95% CrI, 10.9-34.4) events per 1000 catheters placed. Other rates of CVC placement complications (per 1000 catheters) were arterial canulation (2.8; 95% CrI, 0.1-10), arterial puncture (16.2; 95% CrI, 11.5-22), and pneumothorax (4.4; 95% CrI, 2.7-6.5). Rates of CVC use complications (per 1000 catheter-days) were malfunction (5.5; 95% CrI, 0.6-38), infection (4.8; 95% CrI, 3.4-6.6), and DVT (2.7; 95% CrI, 1.0-6.2). It was estimated that 30.2 (95% CrI, 21.8-43.0) in 1000 patients with a CVC for 3 days would develop 1 or more serious complication (arterial cannulation, pneumothorax, infection, or DVT). Use of ultrasonography was associated with lower rates of arterial puncture (risk ratio [RR], 0.20; 95% CrI, 0.09-0.44; 13.5 events vs 68.8 events/1000 catheters) and pneumothorax (RR, 0.25; 95% CrI, 0.08-0.80; 2.4 events vs 9.9 events/1000 catheters).

Conclusions and Relevance

Approximately 3% of CVC placements were associated with major complications. Use of ultrasonography guidance may reduce specific risks including arterial puncture and pneumothorax.

The influence of drugs used for sedation during mechanical ventilation on respiratory pattern during unassisted breathing and assisted mechanical ventilation: a physiological systematic review and meta-analysis

Background

Sedation management has a major impact on outcomes in mechanically ventilated patients, but sedation strategies do not generally consider the differential effects of different sedatives on respiration and respiratory pattern. A systematic review was undertaken to quantitatively summarize the known effects of different classes of drugs used for sedation on respiratory pattern during both spontaneous breathing and assisted mechanical ventilation.

Methods

This was a systematic review and meta-analysis conducted using Ovid MEDLINE, Embase, Cochrane Database of Systematic Reviews, and Cochrane Central Register of Controlled Trials up to June 2020 to retrieve studies that measured respiratory parameters before and after the administration of opioids, benzodiazepines, intravenous and inhaled anaesthetic agents, and other hypnotic agents (PROSPERO #CRD42020190017). A random-effects meta-analytic model was employed to estimate the mean percentage change in each of the respiratory indices according to medication exposure with and without mechanical ventilation. Risk of bias was assessed using the Cochrane risk of bias assessment tools.

Findings

Fifty-one studies were included in the analysis. Risk of bias was generally deemed to be low for most studies. Respiratory rate decreased with the administration of opioids in both non-ventilated patients (18% decrease, 95% CI 12-24%) and ventilated patients (26% decrease, 95% CI 15-37%) and increased with inhaled anaesthetics in non-ventilated patients (83% increase, 95% CI 49-118%) and ventilated patients (50% increase, 28-72%). In non-ventilated patients, tidal volume decreased following administration of inhaled aesthetics (55% decrease, 95% CI 25-86%), propofol (36% decrease, 95% CI 20-52%), and benzodiazepines (28% decrease, 95% CI 17-40%); in patients receiving assisted mechanical ventilation, tidal volume was not significantly affected by sedation. Administration of other hypnotic agents was not associated with changes in respiratory rate or tidal volume.

Interpretation

Different classes of drugs used for sedation exert differential effects on respiratory pattern, and this may influence weaning and outcomes in mechanically ventilated patients.

Funding

This study did not receive any funding support.

Lung Recruitment Assessed by Electrical Impedance Tomography (RECRUIT): A Multicenter Study of COVID-19 Acute Respiratory Distress Syndrome

Rationale: Defining lung recruitability is needed for safe positive end-expiratory pressure (PEEP) selection in mechanically ventilated patients. However, there is no simple bedside method including both assessment of recruitability and risks of overdistension as well as personalized PEEP titration. Objectives: To describe the range of recruitability using electrical impedance tomography (EIT), effects of PEEP on recruitability, respiratory mechanics and gas exchange, and a method to select optimal EIT-based PEEP. Methods: This is the analysis of patients with coronavirus disease (COVID-19) from an ongoing multicenter prospective physiological study including patients with moderate-severe acute respiratory distress syndrome of different causes. EIT, ventilator data, hemodynamics, and arterial blood gases were obtained during PEEP titration maneuvers. EIT-based optimal PEEP was defined as the crossing point of the overdistension and collapse curves during a decremental PEEP trial. Recruitability was defined as the amount of modifiable collapse when increasing PEEP from 6 to 24 cm H2O (ΔCollapse24-6). Patients were classified as low, medium, or high recruiters on the basis of tertiles of ΔCollapse24-6. Measurements and Main Results: In 108 patients with COVID-19, recruitability varied from 0.3% to 66.9% and was unrelated to acute respiratory distress syndrome severity. Median EIT-based PEEP differed between groups: 10 versus 13.5 versus 15.5 cm H2O for low versus medium versus high recruitability (P < 0.05). This approach assigned a different PEEP level from the highest compliance approach in 81% of patients. The protocol was well tolerated; in four patients, the PEEP level did not reach 24 cm H2O because of hemodynamic instability. Conclusions: Recruitability varies widely among patients with COVID-19. EIT allows personalizing PEEP setting as a compromise between recruitability and overdistension. Clinical trial registered with www.clinicaltrials.gov (NCT04460859).

Importance of assessing biomarkers and physiological parameters of anemia-induced tissue hypoxia in the perioperative period

Anemia is associated with increased risk of Acute Kidney Injury (AKI), stroke and mortality in perioperative patients. We sought to understand the mechanism(s) by assessing the integrative physiological responses to anemia (kidney, brain), the degrees of anemia-induced tissue hypoxia, and associated biomarkers and physiological parameters. Experimental measurements demonstrate a linear relationship between blood Oxygen Content (C_aO₂) and renal microvascular PO₂ (y = 0.30x + 6.9, r² = 0.75), demonstrating that renal hypoxia is proportional to the degree of anemia. This defines the kidney as a potential oxygen sensor during anemia. Further evidence of renal oxygen sensing is demonstrated by proportional increase in serum Erythropoietin (EPO) during anemia (y = 93.806*10^-0.02, r² = 0.82). This data implicates systemic EPO levels as a biomarker of anemia-induced renal tissue hypoxia. By contrast, cerebral Oxygen Delivery (DO₂) is defended by a profound proportional increase in Cerebral Blood Flow (CBF), minimizing tissue hypoxia in the brain, until more severe levels of anemia occur. We hypothesize that the kidney experiences profound early anemia-induced tissue hypoxia which contributes to adaptive mechanisms to preserve cerebral perfusion. At severe levels of anemia, renal hypoxia intensifies, and cerebral hypoxia occurs, possibly contributing to the mechanism(s) of AKI and stroke when adaptive mechanisms to preserve organ perfusion are overwhelmed. Clinical methods to detect renal tissue hypoxia (an early warning signal) and cerebral hypoxia (a later consequence of severe anemia) may inform clinical practice and support the assessment of clinical biomarkers (i.e., EPO) and physiological parameters (i.e., urinary PO₂) of anemia-induced tissue hypoxia. This information may direct targeted treatment strategies to prevent adverse outcomes associated with anemia.

Non-invasive support for the hypoxaemic patient

Optimisation of oxygenation strategies in patients with hypoxaemic respiratory failure is a top priority for acute care physicians, as hypoxaemic respiratory failure is one of the leading causes of admission. Various oxygenation methods range from non-invasive face masks to high flow nasal cannulae, which have advantages and disadvantages for this heterogeneous patient group. Focus has turned toward examining the benefits of non-invasive ventilation, as this was heavily researched in resource-limited settings during the COVID-19 pandemic. The oxygenation strategy should be determined on an individualised basis for patients, and with new evidence from the COVID-19 pandemic, providers may now consider placing further emphasis on non-invasive approaches. As non-invasive ventilation continues to be used in increasing frequency, new methods of monitoring patient response, including when to escalate ventilation strategy, will need to be validated.

Non-invasive ventilation for acute hypoxemic respiratory failure, including COVID-19

Optimal initial non-invasive management of acute hypoxemic respiratory failure (AHRF), of both coronavirus disease 2019 (COVID-19) and non-COVID-19 etiologies, has been the subject of significant discussion. Avoidance of endotracheal intubation reduces related complications, but maintenance of spontaneous breathing with intense respiratory effort may increase risks of patients' self-inflicted lung injury, leading to delayed intubation and worse clinical outcomes. High-flow nasal oxygen is currently recommended as the optimal strategy for AHRF management for its simplicity and beneficial physiological effects. Non-invasive ventilation (NIV), delivered as either pressure support or continuous positive airway pressure via interfaces like face masks and helmets, can improve oxygenation and may be associated with reduced endotracheal intubation rates. However, treatment failure is common and associated with poor outcomes. Expertise and knowledge of the specific features of each interface are necessary to fully exploit their potential benefits and minimize risks. Strict clinical and physiological monitoring is necessary during any treatment to avoid delays in endotracheal intubation and protective ventilation. In this narrative review, we analyze the physiological benefits and risks of spontaneous breathing in AHRF, and the characteristics of tools for delivering NIV. The goal herein is to provide a contemporary, evidence-based overview of this highly relevant topic.

Helmet noninvasive support for acute hypoxemic respiratory failure: rationale, mechanism of action and bedside application

Introduction

Helmet noninvasive support may provide advantages over other noninvasive oxygenation strategies in the management of acute hypoxemic respiratory failure. In this narrative review based on a systematic search of the literature, we summarize the rationale, mechanism of action and technicalities for helmet support in hypoxemic patients.

Main results

In hypoxemic patients, helmet can facilitate noninvasive application of continuous positive-airway pressure or pressure-support ventilation via a hood interface that seals at the neck and is secured by straps under the arms. Helmet use requires specific settings. Continuous positive-airway pressure is delivered through a high-flow generator or a Venturi system connected to the inspiratory port of the interface, and a positive end-expiratory pressure valve place at the expiratory port of the helmet;  alternatively, pressure-support ventilation is delivered by connecting the helmet to a mechanical ventilator through a bi-tube circuit. The helmet interface allows continuous treatments with high positive end-expiratory pressure with good patient comfort. Preliminary data suggest that helmet noninvasive ventilation (NIV) may provide physiological benefits compared to other noninvasive oxygenation strategies (conventional oxygen, facemask NIV, high-flow nasal oxygen) in non-hypercapnic patients with moderate-to-severe hypoxemia (PaO₂/FiO₂ ≤ 200 mmHg), possibly because higher positive end-expiratory pressure (10–15 cmH₂O) can be applied for prolonged periods with good tolerability. This improves oxygenation, limits ventilator inhomogeneities, and may attenuate the potential harm of lung and diaphragm injury caused by vigorous inspiratory effort. The potential superiority of helmet support for reducing the risk of intubation has been hypothesized in small, pilot randomized trials and in a network metanalysis.

Conclusions

Helmet noninvasive support represents a promising tool for the initial management of patients with severe hypoxemic respiratory failure. Currently, the lack of confidence with this and technique and the absence of conclusive data regarding its efficacy render helmet use limited to specific settings, with expert and trained personnel. As per other noninvasive oxygenation strategies, careful clinical and physiological monitoring during the treatment is essential to early identify treatment failure and avoid delays in intubation.

The Usefulness of the Rapid Shallow Breathing Index in Predicting Successful Extubation: A Systematic Review and Meta-analysis

BACKGROUND

Clinicians use several measures to ascertain whether individual patients will tolerate liberation from mechanical ventilation, including the rapid shallow breathing index (RSBI).

RESEARCH QUESTION

Given varied use of different thresholds, patient populations, and measurement characteristics, how well does RSBI predict successful extubation?

STUDY DESIGN AND METHODS

We searched six databases from inception through September 2019 and selected studies reporting the accuracy of RSBI in the prediction of successful extubation. We extracted study data and assessed quality independently and in duplicate.

RESULTS

We included 48 studies involving RSBI measurements of 10,946 patients. Pooled sensitivity for RSBI of < 105 in predicting extubation success was moderate (0.83 [95% CI, 0.78-0.87], moderate certainty), whereas specificity was poor (0.58 [95% CI, 0.49-0.66], moderate certainty) with diagnostic ORs (DORs) of 5.91 (95% CI, 4.09-8.52). RSBI thresholds of < 80 or 80 to 105 yielded similar sensitivity, specificity, and DOR. These findings were consistent across multiple subgroup analyses reflecting different patient characteristics and operational differences in RSBI measurement.

INTERPRETATION

As a stand-alone test, the RSBI has moderate sensitivity and poor specificity for predicting extubation success. Future research should evaluate its role as a permissive criterion to undergo a spontaneous breathing trial (SBT) for patients who are at intermediate pretest probability of passing an SBT.

TRIAL REGISTRY

PROSPERO; No.: CRD42020149196; URL: www.crd.york.ac.uk/prospero/.

A rational approach on the use of extracorporeal membrane oxygenation in severe hypoxemia: advanced technology is not a panacea

Veno-venous extracorporeal membrane oxygenation (ECMO) is a helpful intervention in patients with severe refractory hypoxemia either because mechanical ventilation cannot ensure adequate oxygenation or because lung protective ventilation is not feasible. Since ECMO is a highly invasive procedure with several, potentially devastating complications and its implementation is complex and expensive, simpler and less invasive therapeutic options should be first exploited. Low tidal volume and driving pressure ventilation, prone position, neuromuscular blocking agents and individualized ventilation based on transpulmonary pressure measurements have been demonstrated to successfully treat the vast majority of mechanically ventilated patients with severe hypoxemia. Veno-venous ECMO has a place in the small portion of severely hypoxemic patients in whom these strategies fail. A combined analysis of recent ARDS trials revealed that ECMO was used in only 2.15% of patients (n = 145/6736). Nevertheless, ECMO use has sharply increased in the last decade, raising questions regarding its thoughtful use. Such a policy could be harmful both for patients as well as for the ECMO technique itself. This narrative review attempts to describe together the practical approaches that can be offered to the sickest patients before going to ECMO, as well as the rationale and the limitations of ECMO. The benefit and the drawbacks associated with ECMO use along with a direct comparison with less invasive therapeutic strategies will be analyzed.

Evaluation of Older Age and Frailty as Factors Associated With Depression and Postoperative Decision Regret in Patients Undergoing Major Head and Neck Surgery

Importance

Clinicians should understand the prevalence of depression and decision regret in patients with head and neck cancer and whether these factors differ with age or frailty.

Objectives

To assess whether age and frailty are associated with preoperative and/or worsening postoperative depression and postoperative decision regret in patients undergoing major head and neck surgery and to identify additional factors associated with depression and decision regret.

Design, Setting, and Participants

This prospective cohort study was conducted at a single institution, with patients aged 50 years or older undergoing major head and neck surgery recruited from December 1, 2011, to April 30, 2014. Statistical analysis was performed from July 1, 2018, to June 30, 2019.

Main Outcomes and Measures

Frailty, functional, and geriatric depression assessments were completed before surgery and 3, 6, and 12 months after surgery. Decision regret assessment was completed 6 months after surgery. The prevalence of depression and decision regret was determined by age group. Change in depression over time was compared between age groups using a linear-effects model. Variables potentially associated with moderate to severe depression and decision regret were analyzed using a logistic regression model.

Results

The study included 274 patients (68 women and 206 men; mean [SD] age, 67.8 [9.5] years). Of these, 105 (38.3%) were 50 to 64 years of age and 169 (61.7%) were 65 years or older. The rate of preoperative moderate to severe depression was 9.6% (21 of 219), with no difference between younger and older adult cohorts. For both age groups, depression scores increased in the postoperative period from baseline to 6 months. At 12 months, there was a difference in depression scores between the younger and older adult cohort (4.8 [4.6] vs 3.1 [3.6]). A higher preoperative Fried Frailty Index score (odds ratio, 2.58 [95% CI, 1.63-4.06]) was associated with preoperative moderate to severe depression. For all patients, the mean Decision Regret Scale score was 18.2 (range, 0-95), and 26.7% of patients (48 of 180) had moderate to severe regret. There was no difference in Decision Regret Scale scores between younger and older patients. Preoperative depression but not frailty is associated with postoperative moderate to severe decision regret (odds ratio, 1.17 [95% CI, 1.06-1.28]).

Conclusions and Relevance

In this cohort study, there was no difference based on age in the prevalence of moderate to severe depression or decision regret. A higher preoperative frailty score was associated with depression but not decision regret. Preoperative depression was the only factor associated with moderate to severe decision regret on multivariate analysis. Understanding the prevalence of and factors associated with moderate to severe depression and decision regret may aid in identifying patients who would benefit from more extensive preoperative counseling and preoperative and postoperative multispecialty assessment and treatment.

Dyspnea and respiratory muscles ultrasound to predict extubation failure

This study investigated dyspnea intensity and respiratory muscles ultrasound early after extubation to predict extubation failure.It was conducted prospectively in two intensive care units in France and Canada. Patients intubated for at least 48 h were studied within 2 h after an extubation following a successful spontaneous breathing trial. Dyspnea was evaluated by the Dyspnea-Visual Analog Scale from 0 to 10 cm (VAS) and the Intensive Care - Respiratory Distress Observational Scale (range 0-10). The ultrasound thickening fraction of the parasternal intercostal and the diaphragm were measured; limb muscle strength was evaluated using the Medical Research Council score (MRC) (range 0-60).Extubation failure occurred in 21 of the 122 enrolled patients (17%). Dyspnea-VAS and Intensive Care - Respiratory Distress Observational scale were higher in patients with extubation failure versus success: 7 (5-9) cm versus 3 (1-5) cm respectively (p<0.001) and 4.4 (2.5-6.5) versus 2.4 (2.1-2.8) respectively (p<0.001). The ratio of intercostal muscle to diaphragm thickening fraction was significantly higher and MRC was lower in patients with failure (0.9 [0.4-3.0] versus 0.3 [0.2-0.5], p<0.001, and 45 [36-50] versus 52 [44-60], p=0.012). The thickening fraction of the intercostal and its ratio to diaphragm thickening showed the highest area under the receiver operating characteristic curves for an early prediction of extubation failure (0.81). Areas under the receiver operating characteristic curves of Dyspnea-VAS and Intensive Care - Respiratory Distress Observational scale reached 0.78 and 0.74 respectively.Respiratory muscle ultrasound and dyspnea measured within 2 h after extubation predict subsequent extubation failure.

Identifying Subjects at Risk for Diaphragm Atrophy During Mechanical Ventilation Using Routinely Available Clinical Data

BACKGROUND

Diaphragmatic respiratory effort during mechanical ventilation is an important determinant of patient outcome, but direct measurement of diaphragmatic contractility requires specialized instrumentation and technical expertise. We sought to determine whether routinely collected clinical variables can predict diaphragmatic contractility and stratify the risk of diaphragm atrophy.

METHODS

We conducted a secondary analysis of a prospective cohort study on diaphragm ultrasound in mechanically ventilated subjects. Clinical variables, such as breathing frequency, ventilator settings, and blood gases, were recorded longitudinally. Machine learning techniques were used to identify variables predicting diaphragm contractility and stratifying the risk of diaphragm atrophy (> 10% decrease in thickness from baseline). Performance of the variables was evaluated in mixed-effects logistic regression and random-effects tree models using the area under the receiver operating characteristic curve.

RESULTS

Measurements were available for 761 study days in 191 subjects, of whom 73 (38%) developed diaphragm atrophy. No routinely collected clinical variable, alone or in combination, could accurately predict either diaphragm contractility or the development of diaphragm atrophy (model area under the receiver operating characteristic curve 0.63-0.75). The risk of diaphragm atrophy was not significantly different according to the presence or absence of patient-triggered breaths (38.3% vs 38.6%; odds ratio 1.01, 95% CI 0.05-2.03). Diaphragm thickening fraction < 15% during either of the first 2 d of the study was associated with a higher risk of atrophy (44.6% vs 26.1%; odds ratio 2.28, 95% CI 1.05-4.95).

CONCLUSIONS

Diaphragmatic contractility and the risk of diaphragm atrophy could not be reliably determined from routinely collected clinical variables and ventilator settings. A single measurement of diaphragm thickening fraction measured within 48 h of initiating mechanical ventilation can be used to stratify the risk of diaphragm atrophy during mechanical ventilation.

Diaphragm echodensity in mechanically ventilated patients: a description of technique and outcomes

Background

Acute increases in muscle sonographic echodensity reflect muscle injury. Diaphragm echodensity has not been measured in mechanically ventilated patients. We undertook to develop a technique to characterize changes in diaphragm echodensity during mechanical ventilation and to assess whether these changes are correlated with prolonged mechanical ventilation.

Methods

Diaphragm ultrasound images were prospectively collected in mechanically ventilated patients and in 10 young healthy subjects. Echodensity was quantified based on the right-skewed distribution of grayscale values (50th percentile, ED50; 85^th percentile, ED85). Intra- and inter-analyzer measurement reproducibility was determined. Outcomes recorded included duration of ventilation and ICU complications (including reintubation, tracheostomy, prolonged ventilation, or death).

Results

Echodensity measurements were obtained serially in 34 patients comprising a total of 104 images. Baseline (admission) diaphragm ED85 was increased in mechanically ventilated patients compared to younger healthy subjects (median 56, interquartile range (IQR) 42–84, vs. 39, IQR 36–52, p = 0.04). Patients with an initial increase in median echodensity over time (≥ + 10 in ED50 from baseline) had fewer ventilator-free days to day 60 (n = 13, median 46, IQR 0–52) compared to patients without this increase (n = 21, median 53 days, IQR 49–56, unadjusted p = 0.03). Both decreases and increases in diaphragm thickness during mechanical ventilation were associated with increases in ED50 over time (adjusted p = 0.03, conditional R² = 0.80) and the association between increase in ED50 and outcomes persisted after adjusting for changes in diaphragm thickness.

Conclusions

Many patients exhibit increased diaphragm echodensity at the outset of mechanical ventilation. Increases in diaphragm echodensity during the early course of mechanical ventilation are associated with prolonged mechanical ventilation. Both decreases and increases in diaphragm thickness during mechanical ventilation are associated with increased echodensity.

Evaluation of the Braden scale in predicting surgical outcomes in older patients undergoing major head and neck surgery

BACKGROUND

Being able to predict negative postoperative outcomes is important for helping select patients for treatment as well for informed decision-making by patients. Frailty measures are often time and resource intensive to use as screening measures, whereas the Braden scale, a commonly used measure to assess patients at risk of developing pressure ulcers after surgery, may be a potential tool to predict postoperative complication rates and longer length of stay (LOS) in patients undergoing major head and neck cancer surgery.

METHODS

A retrospective analysis of Braden scale scores was performed on a prospectively collected cohort of patients undergoing major head and neck surgery recruited between December 2011 and April 2014. The association of Braden scale score with the primary outcomes of complications and LOS was analyzed using logistic regression and linear regression models on univariate analysis (UVA), respectively. Multivariate analysis (MVA) was performed based on a backward stepwise selection algorithm.

RESULTS

There were 232 patients with a mean (SD) Braden scale score of 14.9 (2.8) with a range from 9 to 23. The Braden scale (β = -.07 per point; 95% CI -0.09, -0.04, P < .001) was an independent predictor of increased LOS on UVA, but not on MVA when adjusted for other variables. For overall complications, as well as type of complication, the Braden scale score was not a significant predictor of complications on either UVA or MVA.

CONCLUSION

In the sample population, the Braden scale did not demonstrate an ability to predict negative outcomes in head and neck surgery patients.

LEVEL OF EVIDENCE

Level 2b individual cohort study.

Longitudinal Assessment of Frailty and Quality of Life in Patients Undergoing Head and Neck Surgery

OBJECTIVE

To understand changes in frailty and quality of life (QOL) in frail versus non-frail patients undergoing surgery for head and neck cancer (HNC).

METHODS

Prospective cohort study of patients (median age 67 (50, 88)) with HNC undergoing surgery from December 2011 to April 2014. Fried's Frailty Index, Vulnerable Elders Survey (VES-13), and comprehensive QOL assessments (EORTC QLQ-C30 and HN35) were completed at baseline and 3, 6, and 12-month post-operative visits. Change in frailty and QOL over time was compared between frailty groups (non-frail (score 0), pre-frail (score 1-2), and frail (score 3-5)) using a mixed effects model. Predictors of long-term elevated frailty (12 months > baseline) were analyzed using logistic regression.

RESULTS

The study had 108 patients classified as non-frail (47%), 104 pre-frail (mean (SD) 1.3 (0.4), 45%), and 17 frail (3.4 (0.6); 7%). Frailty score decreased significantly for frail patients 3 months post-operatively (2.1 (1.0); P = .002) and remained significantly lower than baseline at 6 and 12 months (2.1 (1.4); P = .0008 and 2.2 (1.5); P = .005, respectively) while frailty score increased for non-frail patients at 3 months (1.1 (1.0); P < .001) and then decreased. Forty-eight patients (21%) had long-term elevated frailty, with baseline frailty and marital status identified as predictors on univariate analysis. The frail population had significantly worse QOL scores at baseline, which persisted 12 months post-operatively.

CONCLUSIONS

Frail patients demonstrate a decrease in frailty score following surgical treatment of HNC. Frail patients have significantly worse QOL scores on longitudinal assessment and would benefit from supportive services throughout their care.

LEVEL OF EVIDENCE

3 Laryngoscope, 131:E2232-E2242, 2021.

Anesthesiologist to Patient Communication: A Systematic Review

IMPORTANCE

Many patients are admitted to the intensive care unit following surgery, and some of them will experience incomplete recovery. For patients in this situation, preoperative discussions regarding patient values and preferences may direct care decisions. Existing literature shows that it is uncommon for surgeons to have these conversations preoperatively; it is unclear whether anesthesia professionals engage with patients on this topic prior to surgery.

OBJECTIVE

To review the literature on communication between patients and anesthesia professionals, with a focus on discussions related to postoperative critical care.

EVIDENCE REVIEW

MEDLINE and Web of Science were searched using specific search criteria from January 1980 to April 2020. Studies describing encounters between patients and anesthesia professionals were selected, and data regarding study objectives, study design, methodology, measures, outcomes, patient characteristics, and clinical setting were extracted and collated. The Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) reporting guideline was followed.

FINDINGS

A total of 12 studies including 1284 individual patient encounters were eligible for inclusion in the review. These studies demonstrated that communication between patients and anesthesia professionals related to postoperative care is rare: only 2 studies reported communication regarding adverse postoperative events, and this communication behavior was reported in only 46 of 1284 consultations (3.6%) across all studies. Additional findings were that communication during these encounters is dominated by anesthetic planning and perioperative logistics, with variable discussion of perioperative risks vs benefits and infrequent elicitation of patient values and preferences. Some data suggest that patients wish to be involved in perioperative decision-making but are often limited by an incomplete understanding of risks and benefits.

CONCLUSIONS AND RELEVANCE

This systematic review found that communication in anesthesia is dominated by anesthetic planning and discussion of preoperative logistics, whereas postoperative critical care is rarely discussed. Most patients who are admitted to an intensive care unit after a major operation will not have had a discussion regarding goals of care specific to protracted recovery or prolonged intensive care with their anesthesiologist.

Proportional modes of ventilation: technology to assist physiology

Proportional modes of ventilation assist the patient by adapting to his/her effort, which contrasts with all other modes. The two proportional modes are referred to as neurally adjusted ventilatory assist (NAVA) and proportional assist ventilation with load-adjustable gain factors (PAV+): they deliver inspiratory assist in proportion to the patient’s effort, and hence directly respond to changes in ventilatory needs. Due to their working principles, NAVA and PAV+ have the ability to provide self-adjusted lung and diaphragm-protective ventilation. As these proportional modes differ from ‘classical’ modes such as pressure support ventilation (PSV), setting the inspiratory assist level is often puzzling for clinicians at the bedside as it is not based on usual parameters such as tidal volumes and PaCO₂ targets. This paper provides an in-depth overview of the working principles of NAVA and PAV+ and the physiological differences with PSV. Understanding these differences is fundamental for applying any assisted mode at the bedside. We review different methods for setting inspiratory assist during NAVA and PAV+ , and (future) indices for monitoring of patient effort. Last, differences with automated modes are mentioned.

Association of Low Baseline Diaphragm Muscle Mass With Prolonged Mechanical Ventilation and Mortality Among Critically Ill Adults

IMPORTANCE

Low diaphragm muscle mass at the outset of mechanical ventilation may predispose critically ill patients to poor clinical outcomes.

OBJECTIVE

To determine whether lower baseline diaphragm thickness (Tdi) is associated with delayed liberation from mechanical ventilation and complications of acute respiratory failure (reintubation, tracheostomy, prolonged ventilation >14 days, or death in the hospital).

DESIGN, SETTING, AND PARTICIPANTS

Secondary analysis (July 2018 to June 2019) of a prospective cohort study (data collected May 2013 to January 2016). Participants were 193 critically ill adult patients receiving invasive mechanical ventilation at 3 intensive care units in Toronto, Ontario, Canada.

EXPOSURES

Diaphragm thickness was measured by ultrasonography within 36 hours of intubation and then daily. Patients were classified as having low or high diaphragm muscle mass according to the median baseline Tdi.

MAIN OUTCOMES AND MEASURES

The primary outcome was time to liberation from ventilation accounting for the competing risk of death and adjusting for age, body mass index, severity of illness, sepsis, change in Tdi during ventilation, baseline comorbidity, and study center. Secondary outcomes included in-hospital death and complications of acute respiratory failure.

RESULTS

A total of 193 patients were available for analysis; the mean (SD) age was 60 (15) years, 73 (38%) were female, and the median (interquartile range) Sequential Organ Failure Assessment score was 10 (8-13). Median (interquartile range) baseline Tdi was 2.3 (2.0-2.7) mm. In the primary prespecified analysis, baseline Tdi of 2.3 mm or less was associated with delayed liberation from mechanical ventilation (adjusted hazard ratio for liberation, 0.51; 95% CI, 0.36-0.74). Lower baseline Tdi was associated a higher risk of complications of acute respiratory failure (adjusted odds ratio, 1.77; 95% CI, 1.20-2.61 per 0.5-mm decrement) and prolonged weaning (adjusted odds ratio, 2.30; 95% CI, 1.42-3.74). Lower baseline Tdi was also associated with a higher risk of in-hospital death (adjusted odds ratio, 1.47; 95% CI, 1.00-2.16 per 0.5-mm decrement), particularly after discharge from the intensive care unit (adjusted odds ratio, 2.68; 95% CI, 1.35-5.32 per 0.5-mm decrement).

CONCLUSIONS AND RELEVANCE

In this study, low baseline diaphragm muscle mass in critically ill patients was associated with prolonged mechanical ventilation, complications of acute respiratory failure, and an increased risk of death in the hospital.

The Impact of High-Flow Nasal Oxygen in the Immunocompromised Critically Ill: A Systematic Review and Meta-Analysis

BACKGROUND

High-flow nasal-cannula (HFNC) may be an oxygen modality useful for preventing invasive mechanical ventilation and mortality; however, its role in acute hypoxemic respiratory failure is not clearly defined. We sought to evaluate the impact of HFNC on mortality across immunocompromised subjects compared to alternative noninvasive oxygen therapies, namely conventional oxygen therapy and noninvasive ventilation (NIV).

METHODS

We systematically searched the major databases to identify randomized, controlled trials (RCTs) or observational studies (until May 2018). We included studies reporting the use of HFNC in immunocompromised subjects and evaluated its impact on mortality and invasive mechanical ventilation.

RESULTS

Upon review of 6,506 titles, 13 studies (1,956 subjects) fulfilled our inclusion criteria (4 RCTs, 9 observational studies). The predominant cause of immunocompromised status was cancer. Bacterial pneumonia was the most common cause of acute hypoxemic respiratory failure with a median P_aO2/F_IO2 of 145 mm Hg (interquartile range 115-175). HFNC was used as the first oxygen strategy in 474 subjects compared to NIV (242 subjects) and conventional O₂ therapy (703 subjects). There was a 46% rate of invasive mechanical ventilation and 36% mortality. Mortality at the longest available follow-up was lower with HFNC compared to the oxygen therapy controls (NIV or conventional O₂ therapy) in 7 studies (1,429 subjects; relative risk 0.72, 95% CI 0.56-0.93, P = .01). There was a lower rate of invasive mechanical ventilation with HFNC compared to the oxygen therapy controls across 8 studies (1,529 subjects, relative risk 0.81, 95% CI 0.67-0.96, P = .02). These results were robust across a series of sensitivity analyses.

CONCLUSIONS

There exists a need to develop a greater evidence base evaluating the utility of HFNC in immunocompromised subjects. In our exploratory analysis, HFNC was found to decrease mortality and use of invasive mechanical ventilation compared to alternative noninvasive oxygen controls. These results are meant to be exploratory. Higher-quality studies evaluating a more homogeneous population are needed to further elucidate its benefit.

Optimal Ventilator Strategies in Acute Respiratory Distress Syndrome

Mechanical ventilation practices in patients with acute respiratory distress syndrome (ARDS) have progressed with a growing understanding of the disease pathophysiology. Paramount to the care of affected patients is the delivery of lung-protective mechanical ventilation which prioritizes tidal volume and plateau pressure limitation. Lung protection can probably be further enhanced by scaling target tidal volumes to the specific respiratory mechanics of individual patients. The best procedure for selecting optimal positive end-expiratory pressure (PEEP) in ARDS remains uncertain; several relevant issues must be considered when selecting PEEP, particularly lung recruitability. Noninvasive ventilation must be used with caution in ARDS as excessively high respiratory drive can further exacerbate lung injury; newer modes of delivery offer promising approaches in hypoxemic respiratory failure. Airway pressure release ventilation offers an alternative approach to maximize lung recruitment and oxygenation, but clinical trials have not demonstrated a survival benefit of this mode over conventional ventilation strategies. Rescue therapy with high-frequency oscillatory ventilation is an important option in refractory hypoxemia. Despite a disappointing lack of benefit (and possible harm) in patients with moderate or severe ARDS, possibly due to lung hyperdistention and right ventricular dysfunction, high-frequency oscillation may improve outcome in patients with very severe hypoxemia.

High-flow nasal oxygen versus noninvasive ventilation in adult patients with cystic fibrosis: a randomized crossover physiological study

Background

Noninvasive ventilation (NIV) is the first-line treatment of adult patients with exacerbations of cystic fibrosis (CF). High-flow nasal oxygen therapy (HFNT) might benefit patients with hypoxemia and can reduce physiological dead space. We hypothesized that HFNT and NIV would similarly reduce work of breathing and improving breathing pattern in CF patients. Our objective was to compare the effects of HFNT versus NIV in terms of work of breathing, assessed noninvasively by the thickening fraction of the diaphragm (TFdi, measured with ultrasound), breathing pattern, transcutaneous CO₂ (PtcCO₂), hemodynamics, dyspnea and comfort.

Methods

Adult CF patients who had been stabilized after requiring ventilatory support for a few days were enrolled and ventilated with HFNT and NIV for 30 min in crossover random order.

Results

Fifteen patients were enrolled. Compared to baseline, HFNT, but not NIV, reduced respiratory rate (by 3 breaths/min, p = 0.01) and minute ventilation (by 2 L/min, p = 0.01). Patients also took slightly larger tidal volumes with HFNT compared to NIV (p = 0.02). TFdi per breath was similar under the two techniques and did not change from baseline. MAP increased from baseline with NIV and compared to HFNT (p ≤ 0.01). Comfort was poorer with the application of both HFNT and NIV than baseline. No differences were found for heart rate, SpO₂, PtcCO₂ or dyspnea.

Conclusions

In adult CF patients stabilized after indication for ventilatory support, HFNT and NIV have similar effects on diaphragmatic work per breath, but high-flow therapy confers additional physiological benefits by decreasing respiratory rate and minute ventilation.

Clinical trial registration

Ethics Committee of St. Michael’s Hospital (REB #14-338) and clinicaltrial.gov (NCT02262871).

Electronic supplementary material

The online version of this article (10.1186/s13613-018-0432-4) contains supplementary material, which is available to authorized users.

Effort to Breathe with Various Spontaneous Breathing Trial Techniques. A Physiologic Meta-analysis

RATIONALE

Spontaneous breathing trials (SBTs) are designed to simulate conditions after extubation, and it is essential to understand the physiologic impact of different methods.

OBJECTIVES

We conducted a systematic review and pooled measures reflecting patient respiratory effort among studies comparing SBT methods in a meta-analysis.

METHODS

We searched Medline, Excerpta Medica Database, and Web of Science from inception to January 2016 to identify randomized and nonrandomized clinical trials reporting physiologic measurements of respiratory effort (pressure-time product) or work of breathing during at least two SBT techniques. Secondary outcomes included the rapid shallow breathing index (RSBI), and effort measured before and after extubation. The quality of physiologic measurement and research design was appraised for each study. Outcomes were analyzed using ratio of means.

MEASUREMENTS AND MAIN RESULTS

Among 4,138 citations, 16 studies (n = 239) were included. Compared with T-piece, pressure support ventilation significantly reduced work by 30% (ratio of means [RoM], 0.70; 95% confidence interval [CI], 0.57-0.86), effort by 30% (RoM, 0.70; 95% CI, 0.60-0.82), and RSBI by 20% (RoM, 0.80; 95% CI, 0.75-0.86). Continuous positive airway pressure had significantly lower pressure-time product by 18% (RoM, 0.82; 95% CI, 0.68-0.999) compared with T-piece, and reduced RSBI by 16% (RoM, 0.84; 95% CI, 0.74-0.95). Studies comparing SBTs with the postextubation period demonstrated that pressure support induced significantly lower effort and RSBI; T-piece reduced effort, but not the work, compared with postextubation. Work, effort, and RSBI measured while intubated on the ventilator with continuous positive airway pressure of 0 cm H₂O were no different than extubation.

CONCLUSIONS

Pressure support reduces respiratory effort compared with T-piece. Continuous positive airway pressure of 0 cm H₂O and T-piece more accurately reflect the physiologic conditions after extubation.

High-Frequency Oscillatory Ventilation in Adults With ARDS: Past, Present, and Future

High-frequency oscillatory ventilation (HFOV) is a unique mode of mechanical ventilation that uses nonconventional gas exchange mechanisms to deliver ventilation at very low tidal volumes and high frequencies. The properties of HFOV make it a potentially ideal mode to prevent ventilator-induced lung injury in patients with ARDS. Despite a compelling physiological basis and promising experimental data, large randomized controlled trials have not detected an improvement in survival with the use of HFOV, and its use as an early lung-protective strategy in patients with ARDS may be harmful. Nevertheless, HFOV still has an important potential role in the management of refractory hypoxemia. Careful attention should be paid to right ventricular function and lung stress when applying HFOV. This review discusses the physiological principles, clinical evidence, practical applications, and future prospects for the use of HFOV in patients with ARDS.

Comparing the traditional and Multiple Mini Interviews in the selection of post-graduate medical trainees

BACKGROUND

The traditional, panel style interview and the multiple mini interview (MMI) are two options to use in the selection of medical trainees with each interview format having inherent advantages and disadvantages. Our aim was to compare the traditional and MMI on the same cohort of postgraduate applicants to the Department of Otolaryngology - Head & Neck Surgery at the University of Toronto.

METHOD

Twenty-seven applicants from the 2010 Canadian Residency Matching Service selected for interview at the University of Toronto, Department of Otolaryngology - Head & Neck Surgery were included in the study. Each applicant participated in both a traditional interview and MMI.

RESULTS

Traditional interviews marked out of a total maximum score of 570. On the traditional interview, scores ranged from 397-543.5 (69.6 - 95.3%), the mean was 460.2. The MMI maximum score was out of 180. MMI scores ranged from 93 - 146 (51.7 - 81.1%) with a mean of 114.8. Traditional interview total scores were plotted against MMI total scores. Scores correlated reasonably well, Pearson Correlation = 0.315 and is statistically significant at p = 0.001. Inter-interview reliability for the two interview methods was 0.038, with poor overall agreement 0.07%.

CONCLUSIONS

MMI and traditional interview scores are correlated but do not reliably lead to the same rank order. We have demonstrated that these two interview formats measure different characteristics. One format may also be less reliable leading to greater variation in final rank. Further validation research is certainly required.

Extracorporeal carbon dioxide removal in patients with chronic obstructive pulmonary disease: a systematic review

INTRODUCTION

Extracorporeal carbon dioxide removal (ECCO2R) has been proposed for hypercapnic respiratory failure in chronic obstructive pulmonary disease (COPD) exacerbations, to avoid intubation or reduce length of invasive ventilation. Balance of risks, efficacy, and benefits of ECCO2R in patients with COPD is unclear.

METHODS

We systematically searched MEDLINE and EMBASE to identify all publications reporting use of ECCO2R in COPD. We looked at physiological and clinical efficacy. A favorable outcome was defined as prevention of intubation or successful extubation. Major and minor complications were compiled.

RESULTS

We identified 3123 citations. Ten studies (87 patients), primarily case series, met inclusion criteria. ECCO2R prevented intubation in 65/70 (93%) patients and assisted in the successful extubation of 9/17 (53%) mechanically ventilated subjects. One case-control study matching to noninvasively ventilated controls reported lower intubation rates and hospital mortality with ECCO2R that trended toward significance. Physiological data comparing pre- to post-ECCO2R changes suggest improvements for pH (0.07-0.15 higher), PaCO2 (25 mmHg lower), and respiratory rate (7 breaths/min lower), but not PaO2/FiO2. Studies reported 11 major (eight bleeds requiring blood transfusion of 2 units, and three line-related complications, including one death related to retroperitoneal bleeding) and 30 minor complications (13 bleeds, five related to anticoagulation, and nine clotting-related device malfunctions resulting in two emergent intubations).

CONCLUSION

The technique is still experimental and no randomized trial is available. Recognizing selection bias associated with case series, there still appears to be potential for benefit of ECCO2R in patients with COPD exacerbations. However, it is associated with frequent and potentially severe complications. Higher-quality studies are required to better elucidate this risk-benefit balance.

Corrosion casting of the subglottis following endotracheal tube intubation injury: a pilot study in Yorkshire piglets

PURPOSE

Subglottic stenosis can result from endotracheal tube injury. The mechanism by which this occurs, however, is not well understood. The purpose of this study was to examine the role of angiogenesis, hypoxia and ischemia in subglottic mucosal injury following endotracheal intubation.

METHODS

Six Yorkshire piglets were randomized to either a control group (N=3, ventilated through laryngeal mask airway for corrosion casting) or accelerated subglottic injury group through intubation and induced hypoxia as per a previously described model (N=3). The vasculature of all animals was injected with liquid methyl methacrylate. After polymerization, the surrounding tissue was corroded with potassium hydroxide. The subglottic region was evaluated using scanning electron microscopy looking for angiogenic and hypoxic or degenerative features and groups were compared using Mann-Whitney tests and Friedman's 2-way ANOVA.

RESULTS

Animals in the accelerated subglottic injury group had less overall angiogenic features (P=.002) and more overall hypoxic/degenerative features (P=.000) compared with controls. Amongst angiogenic features, there was decreased budding (P=.000) and a trend toward decreased sprouting (P=.037) in the accelerated subglottic injury group with an increase in intussusception (P=.004), possibly representing early attempts at rapid revascularization. Amongst hypoxic/degenerative features, extravasation was the only feature that was significantly higher in the accelerated subglottic injury group (P=.000).

CONCLUSIONS

Subglottic injury due to intubation and hypoxia may lead to decreased angiogenesis and increased blood vessel damage resulting in extravasation of fluid and a decreased propensity toward wound healing in this animal model.

A solitary tonsil can cause severe obstructive sleep apnea

Hypertrophy of the tonsils and adenoids is the most common cause of pediatric obstructive sleep apnea. Bilateral tonsillectomy, most commonly performed with adenoidectomy, is the accepted treatment for obstructive sleep apnea. We report the unusual case of a child who underwent unilateral tonsillectomy and adenoidectomy at another institution and subsequently presented to us with persistent severe obstructive sleep apnea and a diagnosis of attention deficit hyperactivity disorder. The adenoids were not obstructing the choanae. The remaining tonsil was removed and the patient's sleep apnea resolved. This is the first objectively documented report of a solitary tonsil causing severe obstructive sleep apnea (using polysomnography) that resolved after removal of the remaining tonsil.