Effects of Intra-operative Cardiopulmonary Variability On Post-operative Pulmonary Complications in Major Non-cardiac Surgery: A Retrospective Cohort Study

Intraoperative cardiopulmonary variables are well-known predictors of postoperative pulmonary complications (PPC), traditionally quantified by median values over the duration of surgery. However, it is unknown whether cardiopulmonary instability, or wider intra-operative variability of the same metrics, is distinctly associated with PPC risk and severity. We leveraged a retrospective cohort of adults (n = 1202) undergoing major non-cardiothoracic surgery. We used multivariable logistic regression to evaluate the association of two outcomes (1)moderate-or-severe PPC and (2)any PPC with two sets of exposure variables- (a)variability of cardiopulmonary metrics (inter-quartile range, IQR) and (b)median intraoperative cardiopulmonary metrics. We compared predictive ability (receiver operating curve analysis, ROC) and parsimony (information criteria) of three models evaluating different aspects of the intra-operative cardiopulmonary metrics: Median-based: Median cardiopulmonary metrics alone, Variability-based: IQR of cardiopulmonary metrics alone, and Combined: Medians and IQR. Models controlled for peri-operative/surgical factors, demographics, and comorbidities. PPC occurred in 400(33%) of patients, and 91(8%) experienced moderate-or-severe PPC. Variability in multiple intra-operative cardiopulmonary metrics was independently associated with risk of moderate-or-severe, but not any, PPC. For moderate-or-severe PPC, the best-fit predictive model was the Variability-based model by both information criteria and ROC analysis (area under the curve, AUCVariability-based = 0.74 vs AUCMedian-based = 0.65, p = 0.0015; AUCVariability-based = 0.74 vs AUCCombined = 0.68, p = 0.012). For any PPC, the Median-based model yielded the best fit by information criteria. Predictive accuracy was marginally but not significantly higher for the Combined model (AUCCombined = 0.661) than for the Median-based (AUCMedian-based = 0.657, p = 0.60) or Variability-based (AUCVariability-based = 0.649, p = 0.29) models. Variability of cardiopulmonary metrics, distinct from median intra-operative values, is an important predictor of moderate-or-severe PPC.

Indole-3-Propionic Acid, a Gut Microbiota Metabolite, Protects Against the Development of Postoperative Delirium

OBJECTIVE

The aim was to determine preoperative gut microbiota metabolites that may be associated with postoperative delirium (POD) development in patients and further study in rodents.

SUMMARY BACKGROUND DATA

POD occurs in 9% to 50% of older patients undergoing anesthesia/surgery but lacks effective treatments or prevention. High-throughput metabolomics using liquid chromatography with tandem mass spectrometry has accelerated disease-related biomarkers discovery. We performed metabolomic studies in humans to identify potential metabolite biomarkers linked to POD and examined potential mechanisms in rodents.

METHODS

We performed a prospective observational cohort study to examine the metabolomic changes that were associated with the development of POD. Then the gut microbiota-related metabolomic changes were recapitulated by gut microbiota perturbation in rodents. POD was assessed in mice using a battery of behavioral tests including novel objective test, Y-maze test, open-field test, and buried food test. The mechanisms through which gut microbiota-related metabolomic changes influenced POD were examined using chemogenetics.

RESULTS

Indole-3-propionic acid (IPA) is a gut microbiota metabolite that belongs to the indole family. Baseline plasma levels of IPA were significantly inversely correlated with the onset of POD in 103 (17 cases) human individuals. This relationship was validated in preclinical mouse models for POD: reducing IPA levels through gut microbiota perturbation promoted POD-like behavior. More importantly, IPA administration deterred POD-like behavior. Colonization of germ-free mice with mutant Clostridium sporogenes that did not produce IPA-promoted POD-like behavior. Chemogenetic studies revealed that the protective effect of IPA in mice was mediated, in part, by peroxisome proliferator-activated receptor gamma coactivator 1-alpha in hippocampal interneurons.

CONCLUSIONS

Gut microbiota-derived IPA is an important molecule implicated in the pathogenesis of POD, which could potentially be harnessed for POD prevention.

Narrow band green light effects on headache, photophobia, sleep, and anxiety among migraine patients: an open-label study conducted online using daily headache diary

Background

Narrow band green light (NbGL) has been shown to relieve headache in small numbers of subjects but large-scale real-world assessments are lacking. The goal of this prospective, observational, open-label, real world study was to determine whether treatment with NbGL during the ictal phase of migraine, improves patients' perception of their headache, photophobia, anxiety and same-night sleep.

Methods

The study was conducted in purchasers of the NbGL Lamp in two phases. In Phase I purchasers of the Lamp completed a survey and were asked to participate in a 6-week diary study. In Phase 2 participants completed daily diaries for 6 weeks. Specifically, they were asked to use their judgement/impression/perception when choosing between headache-improved or headache-unimproved after using the NbGL during acute attacks. Diary outcomes of interest included rates of attacks improve in responders (≥50%), non-responders (<50%), super-responders (≥75%), and super non-responders (<30%).

Results

Of 3,875 purchasers of the Lamp for migraine, 698 (18%) agreed to participate, filled out a pre-study survey, and agreed to a 6-week daily headache diary. Complete data were provided by 181 (26%) participants. Using criteria above, 61, 39, 42, and 27% of participants were classified responder, non-responder, super-responder and super non-responder, respectively. Headache improved in 55% of all 3,232 attacks, in 82% of the 1,803 attacks treated by responders, and in 21% of the 1,429 attacks treated by non-responders. Photophobia improved in 53% of all attacks, 68% of the attacks in responders and in 35% of the attacks in non-responders. Anxiety improved in 34% of all attacks, 46% of the responders' attacks, and 18% of the non-responders' attacks. Sleep improved in 49% of all attacks, 59% of the responders' attacks, and 36% of the non-responders' attacks.

Conclusion

This open-label real world study suggests that 2 h of treatment with the lamp during migraine attacks is associated with relief of pain and photophobia, reduction in anxiety, and improved sleep. The absence of rigorous diagnosis and a blinded contemporaneous control group limits the rigor of this interpretation. Improvement in photophobia, anxiety and sleep among the responders may be secondary to the improvement in the headache itself.

Clinical trial registration

ClinicalTrial.gov (NCT04841083).

The association between gut microbiota and postoperative delirium in patients

Postoperative delirium is one of the most common postoperative complications in older patients. Its pathogenesis and biomarkers, however, remain largely undetermined. Majority of human microbiota is gut microbiota and gut microbiota has been shown to regulate brain function. Therefore, this study aimed to determine the association between gut microbiota and postoperative delirium in patients. Of 220 patients (65 years old or older) who had a knee replacement, hip replacement, or laminectomy under general or spinal anesthesia, 86 participants were included in the data analysis. The incidence (primary outcome) and severity of postoperative delirium was assessed for two days. Fecal swabs were collected from participants immediately after surgery. The 16S rRNA gene sequencing was used to assess gut microbiota. Using principal component analyses along with a literature review to identify biologically plausible mechanisms, and three bacterials were studied for their associations with postoperative delirium. Of the 86 participants [age 71.0 (69.0-76.0, 25%-75% percentile of quartile), 53% female], ten (12%) developed postoperative delirium. Postoperative gut bacteria Parabacteroides distasonis (Odds Ratio [OR] 2.13, 95% Confidence Interval (CI): 1.09-4.17, P = 0.026) was associated with postoperative delirium after adjusting for age and sex. The association between delirium and both Prevotella (OR: 0.59, 95% CI: 0.33-1.04, P = 0.067) and Collinsella (OR: 0.57, 95% CI: 0.27-1.24, P = 0.158) did not meet statistical significance. These findings suggest that postoperative gut microbiota (e.g., Parabacteroides distasonis ) may serve as biomarkers in the pathogenesis of postoperative delirium, pending confirmative studies.

OnabotulinumtoxinA alters inflammatory gene expression and immune cells in chronic headache patients

Occipital headache, the perception of pain in the back of the head, is commonly described by patients diagnosed with migraine, tension-type headache, and occipital neuralgia. The greater and lesser occipital nerves play central role in the pathophysiology of occipital headache. In the clinical setup, such headaches are often treated with onabotulinumtoxinA, a neurotoxin capable of disrupting ability of nociceptors to get activated and/or release proinflammatory neuropeptides. Attempting to understand better onabotulinumtoxinA mechanism of action in reducing headache frequency, we sought to determine its effects on expression of inflammatory genes in injected occipital tissues.

To achieve this goal, we injected 40 units of onabotulinumtoxinA into four muscle groups (occipitalis, splenius capitis, semispinalis capitis, and trapezius muscles—all located on one side of the occiput) of patients with chronic bilateral occipital headache scheduled for occipital nerve decompression surgery 1 month later. At the time of surgery, we collected discarded muscle, fascia and periosteum tissues from respective locations on both sides of the neck and occiput and performed targeted transcriptome analyses to determine expression level of inflammatory genes in onabotulinumtoxinA-injected and onabotulinumA-uninjected tissues.

We found that (i) onabotulinumtoxinA alters expression of inflammatory genes largely in periosteum, minimally in muscle and not at all in fascia; (ii) expression of inflammatory genes in uninjected periosteum and muscle is significantly higher in historical onabotulinumA responders than historical non-responders; (iii) in historical responders’ periosteum, onabotulinumA decreases expression of nearly all significantly altered genes, gene sets that define well recognized inflammatory pathways (e.g. pathways involved in adaptive/innate immune response, lymphocyte activation, and cytokine, chemokine, NF-kB, TNF and interferon signalling), and abundance of 12 different immune cell classes (e.g. neutrophils, macrophages, cytotoxic T-, NK-, Th1-, B- and dendritic-cells), whereas in historical non-responders it increases gene expression but to a level that is nearly identical to the level observed in the uninjected periosteum and muscle of historical responders; and surprisingly (iv) that the anti-inflammatory effects of onabotulinumA are far less apparent in muscles and absent in fascia.

These findings suggest that in historical responders’ periosteum—but not muscle or fascia—inflammation contributes to the pathophysiology of occipital headache, and that further consideration should be given to the possibility that onabotulinumA mechanism of action in migraine prevention could also be achieved through its ability to reduce pre-existing inflammation, likely through localized interaction that lead to reduction in abundance of immune cells in the calvarial periosteum.

An Examination of Chronic Pain Indices and the Updated Posttraumatic Stress Disorder Checklist for Diagnostic and Statistical Manual of Mental-Disorders-Fifth Edition

INTRODUCTION

Chronic pain and post-traumatic stress disorder (PTSD) comorbidity is prevalent among veterans and is associated with increased levels of pain severity and pain-related disability. An improved understanding of the relationship between these co-occurring disorders, in addition to effective integrated treatments, will develop by considering the changes to the PTSD diagnostic criteria in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5). The current study examined the relationship between the revised PTSD Checklist for DSM-5 (PCL-5) symptom clusters (i.e., intrusion, avoidance, negative alterations in cognition and mood [NACM], and arousal) and chronic pain measurements (i.e., pain severity, interference, and disability).

MATERIALS AND METHODS

Participants included 103 veterans (ages 26-70, mean = 45.33) participating in a randomized clinical trial examining the efficacy of an interdisciplinary pain management program for chronic musculoskeletal pain. The study was approved by a university system Institutional Review Board and affiliated healthcare system.

RESULTS

The participants with a provisional PTSD diagnosis based on PCL-5 responses (N = 76) had significantly greater pain severity, interference, and disability than the participants without a provisional diagnosis (N = 23). Correlations between symptom clusters and pain measurements were mostly significant and positive with varying strengths. The avoidance symptom cluster, however, had relatively weaker correlations with pain measurements and was not significantly associated with the numeric rating scale of pain severity. Path analyses revealed that, after controlling for avoidance symptoms, significant associations remained between NACM and all the pain measurements. After controlling for NACM symptoms, however, there were no significant associations between avoidance symptoms and pain measurements.

CONCLUSION

The current study highlights a need to re-examine the leading theories about the mutual maintenance of these disorders in order to develop effective integrative treatment approaches. PTSD-related avoidance may have a relatively weaker role in co-occurring chronic pain than the other symptom clusters and may have a qualitatively different role than chronic pain-related avoidance. Future research should explore the relationship between the avoidance in PTSD and the avoidance in chronic pain as well as identify which chronic pain measurements are the most useful when examining the relationship between PTSD and chronic pain. The potential impact of trauma-related cognition and mood on chronic pain indicates that this is an important area for intervention and should be considered in the development of integrated treatments for chronic pain and PTSD among veterans.

Efficacy of different analgesia treatments for abdominal surgery: A network meta-analysis

OBJECTIVE

This study was designed to evaluate the efficacy of analgesia and incidence of postoperative nausea and vomiting (PONV) of several widely used clinical treatments for postoperative analgesia following abdominal surgery through network meta-analysis (NMA) based on published randomized controlled trials (RCTs).

METHODS

This NMA was registered on PROSPERO as CRD 42020169606. Primary outcomes were pain scores (visual analog scale) and accumulative opioid consumption, and secondary outcomes assessed the incidence of PONV at 24 h after surgery.

RESULTS

A total of 215 RCTs and 15,114 patients were identified in this NMA. In comparison with placebo, use of a preoperative paravertebral block (mean: -12.63, 95% CI: -21.12 to -4.13), continuous wound infiltration (mean: -9.68, 95%CI: -13.15 to -6.22) and postoperative wound infiltration (mean: -6.34, 95%CI: -10.59 to -2.08) had significantly lower pain scores, less opioid consumption (mean: -2.00, 95%CI: -3.52 to -0.48; mean: -1.34, 95%CI: -1.87 to -0.81; mean: -1.41, 95%CI: -2.07 to -0.74, respectively) and lower incidence of PONV (OR: 0.30, 95%CI: 0.13 to 0.67; OR: 0.49, 95%CI: 0.24 to 0.98; OR: 0.55, 95%CI: 0.34 to 0.89, respectively).

CONCLUSIONS

The findings from our work provide evidence that preoperative paravertebral block was superior to continuous or postoperative wound infiltration to provide postoperative analgesia, nausea and vomiting after abdominal surgery.

Comparison between acupuncture therapy and gabapentin for chronic pain: a pilot study

BACKGROUND

We examined whether the effect of true electroacupuncture on pain and functionality in chronic pain participants can be differentiated from that of medication (gabapentin) by analyzing quantitative sensory testing (QST).

METHODS

We recruited chronic back and neck pain participants who received six sessions (twice weekly) of true electroacupuncture versus sham electroacupuncture or 3 weeks of gabapentin versus placebo treatment. QST profiles, pain scores, and functionality profile were obtained at baseline (visit 1) and after three sessions (visit 4) or six sessions (visit 7) of acupuncture or 3 weeks of gabapentin or placebo.

RESULTS

A total of 50 participants were analyzed. We found no differences in QST profile changes (p = 0.892), pain reduction (p = 0.222), or functionality (p = 0.254) between the four groups. A major limitation of this pilot study was the limited number of study participants in each group.

CONCLUSION

This pilot study suggests that a large-scale clinical study with an adequate sample size would be warranted to compare acupuncture and medication therapy for chronic pain management.

TRIAL REGISTRATION NUMBER

NCT01678586 (ClinicalTrials.gov).

The Society for Obstetric Anesthesia and Perinatology Interdisciplinary Consensus Statement on Neuraxial Procedures in Obstetric Patients With Thrombocytopenia

Because up to 12% of obstetric patients meet criteria for the diagnosis of thrombocytopenia in pregnancy, it is not infrequent that the anesthesiologist must decide whether to proceed with a neuraxial procedure in an affected patient. Given the potential morbidity associated with general anesthesia for cesarean delivery, thoughtful consideration of which patients with thrombocytopenia are likely to have an increased risk of spinal epidural hematoma with neuraxial procedures, and when these risks outweigh the relative benefits is important to consider and to inform shared decision making with patients. Because there are substantial risks associated with withholding a neuraxial analgesic/anesthetic procedure in obstetric patients, every effort should be made to perform a bleeding history assessment and determine the thrombocytopenia etiology before admission for delivery. Whereas multiple other professional societies (obstetric, interventional pain, and hematologic) have published guidelines addressing platelet thresholds for safe neuraxial procedures, the US anesthesia professional societies have been silent on this topic. Despite a paucity of high-quality data, there are now meta-analyses that provide better estimations of risks. An interdisciplinary taskforce was convened to unite the relevant professional societies, synthesize the data, and provide a practical decision algorithm to help inform risk-benefit discussions and shared decision making with patients. Through a systematic review and modified Delphi process, the taskforce concluded that the best available evidence indicates the risk of spinal epidural hematoma associated with a platelet count ≥70,000 × 106/L is likely to be very low in obstetric patients with thrombocytopenia secondary to gestational thrombocytopenia, immune thrombocytopenia (ITP), and hypertensive disorders of pregnancy in the absence of other risk factors. Ultimately, the decision of whether to proceed with a neuraxial procedure in an obstetric patient with thrombocytopenia occurs within a clinical context. Potentially relevant factors include, but are not limited to, patient comorbidities, obstetric risk factors, airway examination, available airway equipment, risk of general anesthesia, and patient preference.

A test of the fear avoidance model to predict chronic pain outcomes in a polytrauma sample

BACKGROUND

Chronic musculoskeletal pain is a complex problem, particularly for individuals with head injury and comorbid psychiatric conditions. The Fear Avoidance Model offers one of the strongest opportunities to conceptualize comorbid traumatic injury and pain, but this model is largely untested.

OBJECTIVE

This study tests the Fear Avoidance Model of chronic pain using a sample from a study of polytrauma patients in a large Department of Veterans Affairs facility who participated in a federally-funded study of interdisciplinary chronic pain management.

METHODS

The present study comprises a secondary analysis of 93 veterans with chronic pain, head injury, posttraumatic stress symptoms and a history of persistent opioid use. Standardized measures of Fear Avoidance Model risk factors (e.g., pain catastrophizing, fear avoidance beliefs, anxiety, depression) were examined as cross-sectional predictors of pain-related disability.

RESULTS

Secondary data analysis revealed that Fear Avoidance Model factors accounted for almost 40% of the variance in pain-related disability, with pain catastrophizing and depression demonstrating the strongest relationships with disability. A summary variable combining all four factors revealed a 6% increase in disability for each factor that was clinically significant for the sample patients.

CONCLUSIONS

This study represents the first attempt to examine a complex, theoretical model of pain in a comorbid pain and TBI sample. Findings revealed a strong relationship between this model and pain-related disability that outperforms pain intensity ratings. This model could be used to guide better treatment for comorbid pain and TBI.

Use of etomidate in patients with heart failure undergoing noncardiac surgery

BACKGROUND

Patients with symptomatic and asymptomatic heart failure undergoing noncardiac surgery may benefit from the haemodynamic profile of etomidate. However, the safety of etomidate in this population is unknown. We examined anaesthesiologist variation in etomidate use and assessed its safety using an instrumental variable approach to account for differences in treatment selection.

METHODS

A retrospective cohort study of 19 714 patients with heart failure undergoing noncardiac surgery at two tertiary care institutions from January 2006 to December 2017 was performed. The proportion of etomidate use among 294 anaesthesiologists was examined and adjusted risk differences (aRD) for in-hospital and 30-day mortality were calculated using physician preference for etomidate as an instrumental variable.

RESULTS

Etomidate was used in 14.3% (2821/19 714) of patients. Preference for etomidate varied substantially among individual anaesthesiologists with the lowest and highest quartile users using etomidate in 0-4.7% and 20.4-66.7% of their own heart failure patients, respectively. The adjusted instrumental variable analysis showed no significant differences in the risk of in-hospital (aRD -0.2%; 95% confidence interval, -2.4%-1.9%; P=0.83) or 30 day mortality (aRD 0.2%; 95% confidence interval, -2.5%-2.9%; P=0.90). Anaesthesiologists with higher preferences for etomidate were more experienced (greater heart failure and total case volume) than anaesthesiologists with lower preferences for etomidate.

CONCLUSIONS

We found substantial variability in anaesthesiologists' preference for etomidate for use in patients with heart failure undergoing noncardiac surgery. There was no association between etomidate use and in-hospital or 30-day mortality. Etomidate is not inferior to other currently used options for induction of general anaesthesia in patients with heart failure.

The association between migraine and hospital readmission due to pain after surgery: A hospital registry study

BACKGROUND

Migraine has been identified as a risk factor of 30-day hospital readmission after surgery. We aimed to further characterize this association examining pain as a potentially migraine-associated, preventable reason for readmission.

HYPOTHESIS

Compared to patients with no migraine, surgical patients with migraine are at increased risk of 30-day hospital readmission with an admitting diagnosis specifying pain.

METHODS

This hospital registry study examined 150,710 patients aged 18 years and above, who underwent surgery with general anesthesia and mechanical ventilation between 2007 and 2015 at a tertiary care center and two affiliated community hospitals in Massachusetts, USA.

RESULTS

Migraine was associated with an increased risk of 30-day pain-related readmission after surgery (adjusted odds ratio 1.42 [95% confidence interval 1.15-1.75]). The association was stronger for migraine with aura (compared to migraine without aura: Adjusted odds ratio 1.69 [95% confidence interval 1.06-2.70]; compared to no migraine: Adjusted odds ratio 2.20 [95% confidence interval 1.44-3.37]). The predicted adjusted risk of pain-related 30-day readmissions was 9.1 [95% confidence interval 5.3-13.0] in 1000 surgical patients with migraine with aura and 5.4 [95% confidence interval 4.2-6.6] in 1000 patients with migraine without aura, compared to 4.2 [95% confidence interval 3.8-4.5] in 1000 patients with no migraine. Furthermore, migraine was associated with an increased risk of postsurgical 30-day readmission due to a priori defined migraine-related pain (headache or abdominal pain) (adjusted odds ratio 1.55 [95% confidence interval 1.20-2.00]).

CONCLUSION

Patients with migraine undergoing surgery are at increased risk of 30-day hospital readmission due to pain.

Influence of the initial level of consciousness on early, goal-directed mobilization: a post hoc analysis

PURPOSE

Early mobilization within 72 h of intensive care unit (ICU) admission improves functional status at hospital discharge. We aimed to assess the effectiveness of early, goal-directed mobilization in critically ill patients across a broad spectrum of initial consciousness levels.

METHODS

Post hoc analysis of the international, randomized, controlled, outcome-assessor blinded SOMS trial conducted 2011-2015. Randomization was stratified according to the immediate post-injury Glasgow Coma Scale (GCS) (≤ 8 or > 8). Patients received either SOMS-guided mobility treatment with a facilitator or standard care. We used general linear models to test the hypothesis that immediate post-randomization GCS modulates the intervention effects on functional independence at hospital discharge.

RESULTS

Two hundred patients were included in the intention-to-treat analysis. The significant effect of early, goal-directed mobilization was consistent across levels of GCS without evidence of effect modification, for the primary outcome functional independence at hospital discharge (p = 0.53 for interaction), as well as average achieved mobility level during ICU stay (mean achieved SOMS level) and functional status at hospital discharge measured with the functional independence measure. In patients with low GCS, delay to first mobilization therapy was longer (0.7 ± 0.2 days vs. 0.2 ± 0.1 days, p = 0.008), but early, goal-directed mobilization compared with standard care significantly increased functional independence at hospital discharge in this subgroup of patients with immediate post-randomization GCS ≤ 8 (OR 3.67; 95% CI 1.02-13.14; p = 0.046).

CONCLUSION

This post hoc analysis of a randomized controlled trial suggests that early, goal-directed mobilization in patients with an impaired initial conscious state (GCS ≤ 8) is not harmful but effective.

Neuroinflammation of the spinal cord and nerve roots in chronic radicular pain patients

Numerous preclinical studies support the role of spinal neuroimmune activation in the pathogenesis of chronic pain, and targeting glia (eg, microglia/astrocyte)- or macrophage-mediated neuroinflammatory responses effectively prevents or reverses the establishment of persistent nocifensive behaviors in laboratory animals. However, thus far, the translation of those findings into novel treatments for clinical use has been hindered by the scarcity of data supporting the role of neuroinflammation in human pain. Here, we show that patients suffering from a common chronic pain disorder (lumbar radiculopathy), compared with healthy volunteers, exhibit elevated levels of the neuroinflammation marker 18 kDa translocator protein, in both the neuroforamina (containing dorsal root ganglion and nerve roots) and spinal cord. These elevations demonstrated a pattern of spatial specificity correlating with the patients' clinical presentation, as they were observed in the neuroforamen ipsilateral to the symptomatic leg (compared with both contralateral neuroforamen in the same patients as well as to healthy controls) and in the most caudal spinal cord segments, which are known to process sensory information from the lumbosacral nerve roots affected in these patients (compared with more superior segments). Furthermore, the neuroforaminal translocator protein signal was associated with responses to fluoroscopy-guided epidural steroid injections, supporting its role as an imaging marker of neuroinflammation, and highlighting the clinical significance of these observations. These results implicate immunoactivation at multiple levels of the nervous system as a potentially important and clinically relevant mechanism in human radicular pain, and suggest that therapies targeting immune cell activation may be beneficial for chronic pain patients.

Novel Pump Control Technology Accelerates Drug Delivery Onset in a Model of Pediatric Drug Infusion

BACKGROUND

Laboratory data suggest that newly initiated drug infusions reach steady-state delivery after a significant time lag. Depending on drug and carrier flow rates and the infusion system's common volume, lag times may exceed 20 or more minutes, especially in the neonatal/pediatric critical care environment. This study tested the hypothesis that a computer-executed algorithm controlling infusion pumps in a coordinated fashion predictably hastens the achievement of the intended steady-state drug delivery in a model of neonatal/pediatric drug infusion.

METHODS

We constructed an in vitro model of neonatal/pediatric drug infusions through a pediatric 4-Fr central venous catheter at total system flows of 2 mL/h or 12 mL/h, representing a clinically relevant infusion range. Methylene blue served as the model infused drug for quantitative analysis. A novel algorithm, based on Taylor Dispersion Theory of fluid flow through tubes and executed by a computer, generated flow patterns that controlled and coordinated drug and carrier delivery by syringe pumps. We measured the time to achieve the intended steady-state drug delivery by conventional initiation of the drug infusion ("turning on the drug pump") and by algorithm-controlled infusion initiation.

RESULTS

At 2 mL/h total system flow, application of the algorithm reduced the time to achieve half of the intended drug delivery rate (T50) from 17 minutes [17, 18] to 3 minutes [3, 3] (median, interquartile range). At 12 mL/h total system flow, application of the algorithm reduced T50 from 6 minutes [6, 7] to 3 minutes [3, 3] The bootstrapped median difference is -14 (95% confidence interval [CI], -16 to -12, adjusted P=.00192) for 2 mL/h flow and -3 (95% CI, -4 to -3, adjusted P=.02061) for 12 mL/h flow. Compared with conventional initiation, the additional fluid required by the algorithm-directed infusion was 0.43 and 1.03 mL for the low- and high-infusion rates, respectively.

CONCLUSIONS

The output of infusion pumps can be predictably controlled and coordinated by a computer-executed algorithm in a model of neonatal/pediatric drug infusions. Application of an algorithm can reduce the time to achieve the intended rate of infused drug delivery with minimal incremental volume administration.

Early, goal-directed mobilisation in the surgical intensive care unit: a randomised controlled trial

BACKGROUND

Immobilisation predicts adverse outcomes in patients in the surgical intensive care unit (SICU). Attempts to mobilise critically ill patients early after surgery are frequently restricted, but we tested whether early mobilisation leads to improved mobility, decreased SICU length of stay, and increased functional independence of patients at hospital discharge.

METHODS

We did a multicentre, international, parallel-group, assessor-blinded, randomised controlled trial in SICUs of five university hospitals in Austria (n=1), Germany (n=1), and the USA (n=3). Eligible patients (aged 18 years or older, who had been mechanically ventilated for <48 h, and were expected to require mechanical ventilation for ≥24 h) were randomly assigned (1:1) by use of a stratified block randomisation via restricted web platform to standard of care (control) or early, goal-directed mobilisation using an inter-professional approach of closed-loop communication and the SICU optimal mobilisation score (SOMS) algorithm (intervention), which describes patients' mobilisation capacity on a numerical rating scale ranging from 0 (no mobilisation) to 4 (ambulation). We had three main outcomes hierarchically tested in a prespecified order: the mean SOMS level patients achieved during their SICU stay (primary outcome), and patient's length of stay on SICU and the mini-modified functional independence measure score (mmFIM) at hospital discharge (both secondary outcomes). This trial is registered with ClinicalTrials.gov (NCT01363102).

FINDINGS

Between July 1, 2011, and Nov 4, 2015, we randomly assigned 200 patients to receive standard treatment (control; n=96) or intervention (n=104). Intention-to-treat analysis showed that the intervention improved the mobilisation level (mean achieved SOMS 2·2 [SD 1·0] in intervention group vs 1·5 [0·8] in control group, p<0·0001), decreased SICU length of stay (mean 7 days [SD 5-12] in intervention group vs 10 days [6-15] in control group, p=0·0054), and improved functional mobility at hospital discharge (mmFIM score 8 [4-8] in intervention group vs 5 [2-8] in control group, p=0·0002). More adverse events were reported in the intervention group (25 cases [2·8%]) than in the control group (ten cases [0·8%]); no serious adverse events were observed. Before hospital discharge 25 patients died (17 [16%] in the intervention group, eight [8%] in the control group). 3 months after hospital discharge 36 patients died (21 [22%] in the intervention group, 15 [17%] in the control group).

INTERPRETATION

Early, goal-directed mobilisation improved patient mobilisation throughout SICU admission, shortened patient length of stay in the SICU, and improved patients' functional mobility at hospital discharge.

FUNDING

Jeffrey and Judy Buzen.

Use of the Reamer/Irrigator/Aspirator Decreases Carotid and Cranial Embolic Events in a Canine Model

BACKGROUND

Approximately 2 million patients in the United States annually undergo total joint arthroplasty with reaming and placement of intramedullary nails, resulting in extravasation of bone marrow and fat into the circulatory system and potentially causing fat embolism syndrome. Acute and chronic changes in mental status documented after these procedures may be related to embolic events. The Reamer/Irrigator/Aspirator (RIA) device has been shown to decrease intramedullary pressure during reaming. We hypothesized that the use of the RIA in a canine model would reduce the number of microemboli detected in the carotid artery and brain compared with nailing either with or without reaming.

METHODS

Twenty-four large canines underwent unreamed nailing (UR), sequentially reamed nailing (SR), or RIA-reamed nailing (RIA) of bilateral femora (eight dogs per group). During reaming and nailing, the number and size of microemboli transiting the carotid artery were recorded. After euthanasia, the brain was harvested for immunostaining and measurement of microinfarction volumes.

RESULTS

Total embolic load passing through the carotid artery was 0.049 cc (UR), 0.045 cc (SR), and 0.013 cc (RIA). The number and size of microemboli in the UR and SR groups were similar; however, the RIA group had significantly fewer larger-sized (>200-μm) emboli (p = 0.03). Pathologic examination of the brain confirmed particulate emboli, and histologic analyses demonstrated upregulation of stress-related proteins in all groups, with fewer emboli and less evidence of stress for RIA reaming.

CONCLUSIONS

RIA reaming decreased microemboli compared with traditional reaming and unreamed nailing, suggesting that intramedullary pressure and heat are important variables. The documented embolic events and brain stress may help to explain subtle neurobehavioral symptoms commonly seen in patients after undergoing long-bone reaming procedures.

CLINICAL RELEVANCE

RIA reaming decreased cranial embolic events and may have an ameliorating effect on postoperative neurologic sequelae.

Lightning and its association with the frequency of headache in migraineurs: An observational cohort study

Aim

The aim of this article is to determine if lightning is associated with the frequency of headache in migraineurs.

Methods

Participants fulfilling diagnostic criteria for International Headache Society-defined migraine were recruited from sites located in Ohio ( n = 23) and Missouri ( n = 67). They recorded headache activity in a daily diary for three to six months. A generalized estimating equations (GEE) logistic regression determined the odds ratio (OR) of headache on lightning days compared to non-lightning days. Other weather factors associated with thunderstorms were also added as covariates to the GEE model to see how they would attenuate the effect of lightning on headache.

Results

The mean age of the study population was 44 and 91% were female. The OR for headache was 1.31 (95% confidence limits (CL); 1.07, 1.66) during lighting days as compared to non-lightning days. The addition of thunderstorm-associated weather variables as covariates were only able to reduce the OR for headache on lightning days to 1.18 (95% CL; 1.02, 1.37). The probability of having a headache on lightning days was also further increased when the average current of lightning strikes for the day was more negative.

Conclusion

This study suggests that lightning represents a trigger for headache in migraineurs that cannot be completely explained by other meteorological factors. It is unknown if lightning directly triggers headaches through electromagnetic waves or indirectly through production of bioaerosols (e.g. ozone), induction of fungal spores or other mechanisms. These results should be interpreted cautiously until replicated in a second dataset.

Manualized therapy for PTSD: flexing the structure of cognitive processing therapy

OBJECTIVE

This study tested a modified cognitive processing therapy (MCPT) intervention designed as a more flexible administration of the protocol. Number of sessions was determined by client progress toward a priori defined end-state criteria, "stressor sessions" were inserted when necessary, and therapy was conducted by novice CPT clinicians.

METHOD

A randomized, controlled, repeated measures, semicrossover design was utilized (a) to test the relative efficacy of the MCPT intervention compared with a symptom-monitoring delayed treatment (SMDT) condition and (b) to assess within-group variation in change with a sample of 100 male and female interpersonal trauma survivors with posttraumatic stress disorder (PTSD).

RESULTS

Hierarchical linear modeling analyses revealed that MCPT evidenced greater improvement on all primary (PTSD and depression) and secondary (guilt, quality of life, general mental health, social functioning, and health perceptions) outcomes compared with SMDT. After the conclusion of SMDT, participants crossed over to MCPT, resulting in a combined MCPT sample (n = 69). Of the 50 participants who completed MCPT, 58% reached end-state criteria prior to the 12th session, 8% at Session 12, and 34% between Sessions 12 and 18. Maintenance of treatment gains was found at the 3-month follow-up, with only 2 of the treated sample meeting criteria for PTSD. Use of stressor sessions did not result in poorer treatment outcomes.

CONCLUSIONS

Findings suggest that individuals respond at a variable rate to CPT, with significant benefit from additional therapy when indicated and excellent maintenance of gains. Insertion of stressor sessions did not alter the efficacy of the therapy.

A problem-solving early intervention for stroke caregivers: one year follow-up

PURPOSE

The study purposes were to assess the efficacy of a caregiver problem-solving intervention (CPSI) on stroke caregiver physical and psychosocial adaptation compared with a wait-list control (WLC) treatment, and to assess the mediation effects of coping on outcomes.

METHODS

A stress and coping model guided the study design. Outcomes were depression, anxiety, preparedness, life changes, and family functioning. CPSI started during acute rehabilitation and continued 3 months postdischarge. Data were collected at baseline (T1), postintervention (T2), and 6 (T3) and 12 months postdischarge (T4).

RESULTS

Of 255 caregivers, 75% were depressed at baseline. Repeated measures ANOVA of study completers (n = 121) indicated improved T2 depression, life change, and health (ps < .04) favoring the CPSI group. Improvements faded by 6 months. Although no group differences in outcomes were found in the intention-to-treat analysis, growth curve modeling indicated a difference in depression rate of change, favoring the CPSI (p = .04). Perceived health, threat appraisal and rational problem-solving were significant mediators (ps < .05).

CONCLUSIONS

Findings provide direction for future interventions to promote and sustain healthy caregiver adaptation.

Developmental differences in peripheral glabrous skin mechanosensory nerve receptive field and intracellular electrophysiologic properties: phenotypic characterization in infant and juvenile rats

Developmental differences in peripheral neuron characteristics and functionality exist. Direct measurement of active and passive electrophysiologic and receptive field characteristics of single mechanosensitive neurons in glabrous skin was performed and phenotypic characterization of fiber subtypes was applied to analyze developmental differences in peripheral mechanosensitive afferents. After Institutional approval, male Sprague-Dawley infant (P7: postnatal day 7) and juvenile (P28) rats were anesthetized and single cell intracellular electrophysiology was performed in the dorsal root ganglion (DRG) soma of mechanosensitive cells with receptive field (RF) in the glabrous skin of the hindpaw. Passive and active electrical properties of the cells and RF size and characteristics determined. Fiber subtype classification was performed and developmental differences in fiber subtype properties analyzed. RF size was smaller at P7 for both low and high threshold mechanoreceptor (LTMR and HTMR) with no differences between A- and C-HTMR (AHTMR and CHTMR). The RF size was also correlated to anatomic location on glabrous skin, toes having smaller RF. Conduction velocity (CV) was adequate at P28 for AHTMR and CHTMR classification, but not at P7. Only width of the action potential at half height (D50) was significantly different between HTMR at P7, while D50, CV and amplitude of the AP were significant for HTMR at P28. RF size is determined in part by the RF distribution of the peripheral neuron. Developmental differences in RF size occur with larger RF sizes occurring in younger animals. This is consistent with RF size differences determined by measuring RF in the spinal cord, except the peripheral RF is much smaller, more refined, and in some cases pinpoint. Developmental differences make CV alone unreliable for neuron classification. Utilizing integration of all measured parameters allows classification of neurons into subtypes even at the younger ages. This will prove important in understanding changes that occur in the peripheral sensory afferents in the face of ongoing development and injury early in life.

Effects of short-term treadmill exercise training or growth hormone supplementation on diastolic function and exercise tolerance in old rats

Whether the lusitropic potential of short-term exercise in aged rats is linked to an augmentation in the growth hormone/insulin-like growth factor-1 (GH/IGF-1) axis and an alteration in the cardiac renin angiotensin system (RAS) is unknown. Old (28-month-old) male, Fischer 344xBrown Norway rats were randomized to 4 weeks of GH supplementation (300 microg subcutaneous, twice daily) or 4 weeks of treadmill running, or were used as sedentary controls. Six-month-old rats, sedentary or exercised, were used as young controls. Training improved exercise capacity in old animals. Exercise and GH attenuated age-related declines in myocardial relaxation despite an exercise-induced suppression of IGF-1. The regulatory protein, sarcoplasmic Ca2+ adenosine triphosphatase (SERCA2), increased with exercise but not GH. Among aged rats, the cardiac RAS was not altered by training or GH. Thus, the signaling pathway underlying the lusitropic benefit of short-term habitual exercise in the aged rat may be distinct from GH-mediated benefits and independent of the cardiac RAS.

Predicting total knee replacement pain: a prospective, observational study

To describe the natural history of pain after total knee arthroplasty and to identify factors predicting excessive postoperative pain, we used a prospective, observational study assessing clinical and radiographic variables preoperatively and at 1, 3, 6, and 12 months after knee replacement. Data sources included the visual analog pain scale and other measures of patient health, psychologic state, and component reliability. Regression analyses were conducted to identify specific factors predictive of postoperative pain, controlling for inequality of variables, and confirmed using regression diagnostics. For 116 patients (149 knees; mean age, 66 years; 55.2% women), significant pain was reported by 72.3%, 44.4%, 22.6%, 18.4%, and 13.1%, respectively. No intergroup differences existed for anesthesia, weight, age, or gender. Patients with greater preoperative pain had more postoperative pain, used more home therapy, and postoperative manipulations. Preoperative depression and anxiety were associated with heightened pain at 1 year. Pain after knee replacement resolves quickly, declining to approximately (1/2) by 3 months. However, one in eight patients report moderate to severe pain 1 year after surgery despite an absence of clinical or radiographic abnormalities. Development of office-based preoperative screening tools and interventions for these patients may reduce postoperative costs and improve patient-perceived outcomes.

Nicotine and caffeine intake in complex regional pain syndrome

{\it

OBJECTIVE

} Nicotine and caffeine are vasoconstrictors. Complex regional pain syndrome (CRPS) is defined to involve disproportionate pain and autonomic dysfunction [1]. The objectives of this study were to identify the prevalence of smoking and caffeine intake in CRPS, to explore the relationship of pain intensity with smoking and caffeine consumption, and to explore the relationship of pain intensity, anxiety and disability among CRPS patients who smoke, use caffeine, or both. {\it

DESIGN

} One hundred eleven patients, with CRPS type I or II, from two academic rehabilitation pain clinics were reviewed. Data were collected retrospectively by reviewing CRPS patients' self-reported pain level using visual analogue scales (VAS), Beck Depression Inventory (BDI), Pain Disability Index (PDI), and Pain Anxiety Symptoms Scale (PASS). Status of daily smoking and caffeine consumption were also recorded. {\it

RESULTS

} Smoking prevalence among CRPS was significant higher than the national average (p < 0.001). There were no significant relationships between the perceived pain level and either daily smoking, daily caffeine intake, or both (p > 0.430). In patients with CRPS I higher PASS scores were positively associated with dichotomous use of smoking and caffeine (p < 0.05). The PASS scores among patients with CRPS~II were not available for analysis. {\it

CONCLUSIONS

} The smoking prevalence was higher than the national average among patients with CRPS I and II. Among patients with CRPS~I smoking and caffeine consumption were greater in those who reported more pain-related anxiety, but did not influence pain intensity. The clinical implications of these findings will be discussed.