The effect of perioperative benzodiazepine administration on postoperative nausea and vomiting: a systematic review and meta-analysis of randomised controlled trials

BACKGROUND

Despite recent systematic reviews suggesting their benefit for postoperative nausea, vomiting, or both (PONV) prevention, benzodiazepines have not been incorporated into guidelines for PONV prophylaxis because of concerns about possible adverse effects. We conducted an updated meta-analysis to inform future practice guidelines.

METHODS

We included randomised controlled trials (RCTs) of all languages comparing benzodiazepines with non-benzodiazepine comparators in adults undergoing inpatient surgery. Our outcomes were postoperative nausea, vomiting, or both. We assessed risk of bias for RCTs using the Cochrane Risk of Bias tool. We pooled data using a random-effects model and assessed the quality of evidence for each outcome using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach.

RESULTS

We screened 31 413 abstracts and 950 full texts. We included 119 RCTs; 104 were included in quantitative synthesis. Based on moderate certainty evidence, we found that perioperative benzodiazepine administration reduced the incidence of PONV (52 studies, n=5086, relative risk [RR]: 0.77, 95% confidence interval [CI] 0.66-0.89; number needed to treat [NNT] 16; moderate certainty), postoperative nausea (55 studies, n=5916, RR: 0.72, 95% CI 0.62-0.83; NNT 21; moderate certainty), and postoperative vomiting (52 studies, n=5909, RR: 0.74, 95% CI 0.60-0.91; NNT 55; moderate certainty).

CONCLUSIONS

Moderate quality evidence shows that perioperative benzodiazepine administration decreases the incidence of PONV. The results of this systematic review and meta-analysis will inform future clinical practice guidelines.

SYSTEMATIC REVIEW PROTOCOL

The protocol for this systematic review was pre-registered with PROSPERO International Prospective Register of Systematic Reviews (CRD42022361088) and published in BMJ Open (PMID 31831540).

Predictors of mitral valve haemodynamics after mitral valve repair for degenerative mitral regurgitation

OBJECTIVE

Intraoperative predictors of functional mitral valve (MV) stenosis after surgical repair of mitral regurgitation (MR) caused by prolapse remain poorly characterised. This study evaluated the effect of annuloplasty size on postoperative MV haemodynamics during exercise and evaluated predictors of MV hemodynamics.

METHODS

104 patients were randomly assigned to leaflet resection or preservation for surgical repair of MR in the Canadian Mitral Research Alliance CardioLink-2 study. In this post hoc analysis, we compared MV haemodynamics between the two surgical groups and examined the relationship between annuloplasty size and MV haemodynamics 1 year after repair in the combined groups. Echocardiograms were performed at baseline and intraoperatively. Exercise transthoracic echocardiography was performed 1 year postoperatively. Multivariable linear regression analysis was used to identify predictors of exercise MV gradients at follow-up.

RESULTS

Mean age of participants was 65±10 years, and 83% were male. Median annuloplasty size was 34 (IQR 32-36). Dividing by the median, 48 (46%) had annuloplasty size of <34 mm and 56 (54%) had ≥34 mm. Mean and peak exercise gradients at 1 year were 11±5 mm Hg and 22±9 mm Hg in <34, and 6±3 mm Hg and 14±5 mm Hg in ≥34 (p<0.001). Rate of residual MR was similar in both groups. In multivariable analyses, annuloplasty size of ≥34 mm was associated with lower mean and peak exercise gradients at 12 months, after adjustment for repair type, age, sex, heart rate and body surface area (β -4.1, 95% CI -6 to -3, p<0.001, and β -7 95% CI -10 to -4, p<0.001, respectively). Intraoperative mean and peak MV gradients by transesophageal echocardiography independently predicted mean and peak resting and exercise gradients at follow-up (p<0.001). Similar results were obtained in both leaflet resection and preservation.

CONCLUSION

Annuloplasty size of ≥34 mm is associated with a 4 and 7 mm Hg reduction in mean and peak exercise MV gradients, respectively, 1 year post MV repair regardless of the repair strategy used. Intraoperative TEE MV gradients predict exercise MV gradients 1 year post repair.

TRIAL REGISTRATION NUMBER

NCT02552771.

Predictors of mitral valve hemodynamics after mitral valve repair for degenerative mitral regurgitation: a subanalysis of the CAMRA randomized trial

Introduction

Intra-operative predictors of mid-to-late mitral valve dysfunction after surgical repair of mitral regurgitation (MR) caused by prolapse remain poorly characterized. This study aims to evaluate the effect of annuloplasty prosthesis size on post-operative MV hemodynamics at rest and during exercise, and to identify perioperative predictors of MV dysfunction.

Methods

104 patients were randomly assigned to resection and preservation for surgical treatment of posterior leaflet prolapse in the Canadian Mitral Research Alliance CardioLink-2 study. Echocardiograms were performed at baseline and 1 year postoperatively. Intraoperative TEE was performed to assess immediate MV gradients. Exercise TTE was performed 1 year after repair. Linear regression analysis was used to identify associations between MV indices (rest and peak exercise gradients) at 12 months, and perioperative echocardiographic and clinical factors.

Results

Mean age of participants was 65±10 years, and 83% were male. Larger annuloplasty size was associated with lower transmitral gradients at rest and during peak exercise. In multivariable analysis, annuloplasty size ≥34mm was associated with lower mean and peak rest and exercise gradients at 12 months, after adjustment for repair type, age, sex, and BSA (p&lt;0.001). Higher pre-operative pulmonary artery pressures were associated with reduced functional capacity post-operatively. Intra-operative TEE gradients predict resting and exercise MV hemodynamics at 1 year.

Conclusion

Annuloplasty size ≥34mm is associated with improved MV hemodynamics at rest and during peak exercise 1 year post MV repair. MV repair prior to onset of pulmonary hypertension confers favourable post operative functional capacity. Finally, intra-operative TEE can be used to identify patients at risk of mitral valve dysfunction within 1 year of repair.

Funding Acknowledgement

Type of funding sources: Other. Main funding source(s): The Heart and StrokeFoundation of Ontario (GIA 16-00014666)

Morbidity and mortality in patients managed with high compared with low blood pressure targets during on-pump cardiac surgery: a systematic review and meta-analysis of randomized controlled trials

PURPOSE

Many believe that blood pressure management during cardiac surgery is associated with postoperative outcomes. We conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) to determine the impact of high compared with low intraoperative blood pressure targets on postoperative morbidity and mortality in adults undergoing cardiac surgery on cardiopulmonary bypass (CPB). Our primary objective was to inform the design of a future large RCT.

SOURCE

We searched MEDLINE, EMBASE, Web of Science, CINAHL, and CENTRAL for RCTs comparing high with low intraoperative blood pressure targets in adult patients undergoing any cardiac surgical procedure on CPB. We screened reference lists, grey literature, and conference proceedings.

PRINCIPAL FINDINGS

We included eight RCTs (N =1,116 participants); all examined the effect of blood pressure management only during the CPB. Trial definitions of high compared with low blood pressure varied and, in some, there was a discrepancy between the target and achieved mean arterial pressure. We observed no difference in delirium, cognitive decline, stroke, acute kidney injury, or mortality between high and low blood pressure targets (very-low to low quality evidence). Higher blood pressure targets may have increased the risk of requiring a blood transfusion (three trials; n = 456 participants; relative risk, 1.4; 95% confidence interval, 1.1 to 1.9; P = 0.01; moderate quality evidence) but this finding was based on a small number of trials.

CONCLUSION

Individual trial definitions of high and low blood pressure targets varied, limiting inferences. The effect of high (compared with low) blood pressure targets on other morbidity and mortality after cardiac surgery remains unclear because of limitations with the body of existing evidence. Research to determine the optimal management of blood pressure during cardiac surgery is required.

STUDY REGISTRATION

PROSPERO (CRD42020177376); registered: 5 July 2020.

The team cohesion-performance relationship: A meta-analysis exploring measurement approaches and the changing team landscape

Team cohesion is an important antecedent of team performance, but our understanding of this relationship is mired by inconsistencies in how cohesion has been conceptualized and measured. The nature of teams is also changing, and the effect of this change is unclear. By meta-analyzing the cohesion-performance relationship ( k = 195, n = 12,023), examining measurement moderators, and distinguishing modern and traditional team characteristics, we uncovered various insights. First, the cohesion-performance relationship varies based on degree of proximity. More proximal measures –task cohesion, referent-shift, and behaviorally-focused– show stronger relationships compared to social cohesion, direct consensus, and attitudinally-focused, which are more distal. Differences are more pronounced when performance metrics are also distal. Second, group pride is more predictive than expected. Third, the cohesion-performance relationship and predictive capacity of different measures are changing in modern contexts, but findings pertaining to optimal measurement approaches largely generalized. Lastly, important nuances across modern characteristics warrant attention in research and practice.

Plain Language Summary

Team cohesion is an important antecedent of team performance, but our understanding of this relationship is mired by inconsistencies in how cohesion has been conceptualized and measured. The nature of teams has also changed over time, and the effect of this change is unclear. By meta-analyzing the cohesion-performance relationship ( k = 195, n = 12,023), examining measurement moderators, and distinguishing between modern and traditional team characteristics, we uncovered various insights for both research and practice. First, the cohesion-performance relationship varies based on degree of proximity. Measures that are more proximal to what a team does – those assessing task cohesion, utilizing referent shift items, and capturing behavioral manifestations of cohesion – show stronger relationships with performance compared to those assessing social cohesion, utilizing direct consensus items, and capturing attitudinal manifestations of cohesion, which are more distal. These differences are more pronounced when performance metrics are also more distal. Second, despite being understudied, the group pride-performance relationship was stronger than expected. Third, modern team characteristics are changing both the overall cohesion-performance relationship and the predictive capacity of different measurement approaches, but findings pertaining to the most optimal measurement approaches largely generalized in that these approaches were less susceptible to the influence of modern characteristics. However, in some contexts, distal cohesion metrics are just as predictive as their more proximal counterparts. Lastly, there are important nuances across different characteristics of modern teams that warrant additional research attention and should be considered in practice. Overall, findings greatly advance science and practice pertaining to the team cohesion-performance relationship.

Transfusion requirements in cardiac Surgery III (TRICS III), Ticagrelor Substudy

Background

Ticagrelor, in addition to aspirin, has been demonstrated to reduce morbidity and mortality in patients with acute coronary syndrome compared to clopidogrel with aspirin. The treatment effect appeared to be maintained in the subgroup of patients who underwent urgent surgical revascularization. However, the risk of postoperative bleeding in these patients has not been well described.

Research question

We aimed to establish the effect of ticagrelor exposure within 7 days before surgery on blood loss as measured by postoperative chest tube output and blood product use.

Method

In a nested cohort study of patients enrolled in the Transfusion Requirements in Cardiac Surgery III (TRICS III) trial, we compared chest tube output and blood product use in patients based on their preoperative exposure to ticagrelor ≤3 days versus &gt;3 days before surgery.

Results

Of the 5243 patients in TRICS III, 87 patients were exposed to ticagrelor within 7 days with a mean age of 78 years (SD 6) and 74% were male. Patients exposed to ticagrelor 3 days or less before surgery bled a median of 730 ml (IQR 295, 2195) postoperatively in the first 24 hours postoperatively, compared to 518 ml (IQR 350, 1000) for those for whom ticagrelor was held for more than 3 days. We log-transformed the data and found that recent ticagrelor exposure (≤3 days) was associated with significantly more blood loss compared to no exposure for more than 3 days (P-value: 0.01).

69.6% of patients in the recent exposure group received at least one red blood cell transfusion versus 54.7% in patients exposed to ticagrelor more than 3 days pre-operatively (p-value: 0.214). Platelet and fresh frozen plasma transfusion were 52.2% vs 15.6% (p-value 0.001), and 39.1% vs 9.4% (p-value 0.003), respectively, for ticagrelor exposure ≤3 days compared to &gt;3 days.

Cryoprecipitate use was 17.4% in the ≤3 days group and 3.1% in the &gt;3 days group (p-value 0.04). Only 1 patient in each group received prothrombin complex concentrate (PCC) transfusion. And 1 patient with exposure ≤3 days received Factor VII.

Conclusion

Exposure to ticagrelor within 3 days of surgery is associated with an increased risk of postoperative bleeding as assessed by greater chest tube output at 24 hours and more patients requiring blood product transfusion. A ticagrelor-reversing agent may improve the outcomes of patients who have been recently exposed to ticagrelor and require urgent cardiac surgery.

Funding Acknowledgement

Type of funding source: None

Safety and efficacy of perioperative benzodiazepine administration: study protocol for a systematic review and meta-analysis

INTRODUCTION

Perioperative benzodiazepines are used because of their anxiolytic, sedative and amnestic effects. Evidence has demonstrated an association of benzodiazepines with adverse neuropsychiatric effects. Nonetheless, because of their potential benefits, perioperative benzodiazepines continue to be used routinely. We seek to evaluate the body of evidence of the risks and benefits of benzodiazepine use during the perioperative period.

METHODS AND ANALYSIS

We will search Cochrane CENTRAL, MEDLINE, EMBASE, PsychINFO, CINAHL and Web of Science from inception to March 2019 for randomised controlled trials (RCTs) and observational studies evaluating the administration of benzodiazepine medications as compared with all other medications (or nothing) in patients undergoing cardiac and non-cardiac surgery. We will exclude studies assessing the use of benzodiazepines for procedural sedation or day surgery. We will examine the impact of giving these medications before, during and after surgery. Outcomes of interest include the incidence of delirium, duration of delirium, postprocedure cognitive change, the incidence of intraoperative awareness, patient satisfaction/quality of life/quality of recovery, length-of-stay (LOS) in the intensive care unit (ICU), hospital LOS and in-hospital mortality.Reviewers will screen references and assess eligibility using predefined criteria independently and in duplicate. Two reviewers will independently collect data using prepiloted forms. We will present results separately for RCTs and observational studies. We will pool data using a random effect model and present results as relative risk with 95% CIs for dichotomous outcomes and mean difference with 95% CI for continuous outcomes. We will pool adjusted ORs for observational studies. We will assess risk of bias for individual studies using the Cochrane Collaboration tool for RCTs. For observational studies, we will use tools designed by the Clinical Advances through Research and Information Translation group. Quality of evidence for each outcome will be assessed using the Grading of Recommendations Assessment, Development and Evaluation approach.

ETHICS AND DISSEMINATION

This systematic review involves no patient contact and no interaction with healthcare providers or systems. As such, we did not seek ethics board approval. We will disseminate the findings of our systematic review through the presentation at peer-reviewed conferences and by seeking publication in a peer-reviewed journal.

PROSPERO REGISTRATION NUMBER

CRD42019128144.

P1500Effects of empagliflozin on cardiac function in patients with type 2 diabetes mellitus: echocardiographic substudy of the EMPA-HEART cardiolink-6 trial

Background

The EMPA-HEART trial showed a reduction in left ventricular (LV) mass index by cardiac MRI at 6 months in patients treated with Empagliflozin vs placebo. A secondary analysis of key echocardiographic parameters was performed to provide further insight into the mechanism of LV remodeling.

Methods

All patients enrolled prospectively underwent transthoracic echocardiography (TTE) at baseline and at 6 months. Measurements were performed according to the American Society of Echocardiography guidelines. Key outcomes of interest included changes in diastolic function and right ventricle parameters at 6 months in patients treated with Empagliflozin vs placebo.

Results

A total of 97 patients were enrolled (49 treated with Empagliflozin and 48 in the placebo group). There was no significant difference in the change in average E/E' at 6-months in the Empagliflozin group vs placebo (−0.4 vs +0.2, adjusted difference −0.2, 95% CI [−1.3 to 0.82], p=0.7) Similarly, there was no difference between the groups in secondary TTE parameters (Table 1). Subgroup analyses showed no benefit among patients with baseline LVEF >50% vs. ≤50%, and baseline LV mass index ≥60 g/m2 vs <60 g/m2.

Echocardiographic Parameter Placebo (n=48) Empagliflozin (n=49) Adjusted Difference Between Groups 95% CI P-Value Baseline 6 months Change Baseline 6 months Change LVEF (%)* 55.5 (8.7) 54.3 (8.9) −1.0 (6.5) 58.0 (7.5) 59.1 (8.57) 0.72 (5.1) 2.2 (−0.2, 4.7) 0.1 Diastolic Parameters:   Average E/e' 10.1 (3.1) 10.3 (2.5) 0.2 (3.0) 10.6 (3.0) 10.5 (3.6) −0.4 (2.5) −0.2 (−1.3, 0.8) 0.7   Medial E/e' 12.3 (3.9) 12.5 (3.6) 0.1 (3.7) 12.6 (4.2) 12.6 (5.2) −0.3 (3.3) −0.3 (−1.7, 1.1) 0.7   Lateral E/e' 8.0 (2.8) 8.2 (2.2) 0.2 (2.7) 8.7 (2.6) 8.4 (2.5) −0.4 (2.7) −0.1 (−1.0, 0.8) 0.8   E velocity (cm/sec) 68.6 (15.2) 70.6 (14.7) 1.8 (15.4) 74.4 (18.2) 71.2 (16.8) −3.2 (15.1) −2.3 (−7.9, 3.3) 0.4   A velocity (cm/sec) 74.7 (17.9) 77.9 (18.8) 2.9 (15.9) 76.2 (16.5) 75.8 (14.5) −1.4 (11.7) −3.5 (−8.9, 1.6) 0.2   LA volume index (mL/m2) 32.7 (7.9) 30.8 (8.1) −2.0 (6.7) 30.2 (6.7) 28.7 (5.5) −1.6 (6.5) −0.9 (−3.4, 1.6) 0.5 RV Parameters:   TAPSE (cm) 1.8 (0.5) 1.8 (0.4) 0.1 (0.4) 2.0 (1.2) 1.8 (0.4) −0.3 (1.4) −0.1 (−0.3, 0.1) 0.3   RV S' TDI (cm/sec) 10.9 (2.9) 10.6 (2.5) −0.1 (2.2) 10.4 (2.7) 10.2 (2.6) −0.4 (2.0) −0.3 (−1.2, 0.5) 0.4 *Measured by cardiac MRI. LA, left atrium; LVEF, left ventricular ejection fraction; RV, right ventricle; TAPSE, tricuspid annular plane systolic excursion; TDI, tissue Doppler imaging. Data expressed as mean (standard deviation).

Conclusion

This study showed no significant change in key echocardiographic parameters in patients treated with Empagliflozin, suggesting that changes in loading conditions induced by empagliflozin (i.e. preload) do not mediate the reduction in LV mass.

Reporting preclinical anesthesia study (REPEAT): Evaluating the quality of reporting in the preclinical anesthesiology literature

Poor reporting quality may contribute to irreproducibility of results and failed 'bench-to-bedside' translation. Consequently, guidelines have been developed to improve the complete and transparent reporting of in vivo preclinical studies. To examine the impact of such guidelines on core methodological and analytical reporting items in the preclinical anesthesiology literature, we sampled a cohort of studies. Preclinical in vivo studies published in Anesthesiology, Anesthesia & Analgesia, Anaesthesia, and the British Journal of Anaesthesia (2008-2009, 2014-2016) were identified. Data was extracted independently and in duplicate. Reporting completeness was assessed using the National Institutes of Health Principles and Guidelines for Reporting Preclinical Research. Risk ratios were used for comparative analyses. Of 7615 screened articles, 604 met our inclusion criteria and included experiments reporting on 52 490 animals. The most common topic of investigation was pain and analgesia (30%), rodents were most frequently used (77%), and studies were most commonly conducted in the United States (36%). Use of preclinical reporting guidelines was listed in 10% of applicable articles. A minority of studies fully reported on replicates (0.3%), randomization (10%), blinding (12%), sample-size estimation (3%), and inclusion/exclusion criteria (5%). Statistics were well reported (81%). Comparative analysis demonstrated few differences in reporting rigor between journals, including those that endorsed reporting guidelines. Principal items of study design were infrequently reported, with few differences between journals. Methods to improve implementation and adherence to community-based reporting guidelines may be necessary to increase transparent and consistent reporting in the preclinical anesthesiology literature.

Assessment of safety and efficacy of mesenchymal stromal cell therapy in preclinical models of acute myocardial infarction: a systematic review protocol

BACKGROUND

Despite advances in treatment, acute myocardial infarction (MI) is still associated with significant morbidity and mortality, especially in patients with extensive damage and scar formation. Based on some promising preclinical studies, there is interest in the use of mesenchymal stromal cells (MSCs) to promote cardiac repair after acute MI. However, there is a need for a systematic review of this evidence to summarize the efficacy and safety of MSCs in preclinical models of MI. This will better inform the translation of MSC therapy for acute MI and guide the design of a future clinical trial.

METHODS/DESIGN

A systematic literature search of MEDLINE, Embase, and BIOSIS Previews will be conducted. We will identify comparative preclinical studies (randomized and non-randomized) of myocardial infarction that include animals given MSC therapy versus a vehicle/placebo. The primary outcome will be left ventricular ejection fraction. Secondary and tertiary outcomes will include death, infarct size, measures of cardiac function, biochemical outcomes, and MSC retention and differentiation. Risk of bias will be assessed using the Cochrane Risk of Bias Tool. Subgroup analyses will be performed to measure how various sources of preclinical study heterogeneity affect the direction and magnitude of the primary outcome. We will meta-analyze data using inverse variance random effects modeling.

DISCUSSION

This systematic review of preclinical evidence will provide a summary of the efficacy and safety of MSCs in animal models of MI. The results will help determine whether sufficient evidence exists to conduct a clinical trial in humans and inform its design.

Effect of pneumoperitoneum on renal tissue oxygenation and blood flow in a rat model

OBJECTIVES

To determine the correlation between the renal blood flow (RBF) and tissue oxygenation (PO(2)) at varying intra-abdominal pressures (IAPs) and to compare the effects on renal blood flow from carbon dioxide-induced pneumoperitoneum.

METHODS

Carbon dioxide pneumoperitoneum was established in Sprague-Dawley rats (n = 6). Licox oxygen/temperature tissue probes were laparoscopically inserted into the renal parenchyma, with the renal PO(2) and RBF recorded every 30 seconds while the IAP was gradually increased. Microprobes measuring the RBF, mean arterial pressures and serum pH were placed into the parenchyma to compare the effects of carbon dioxide pneumoperitoneum (n = 7) with that of open surgery (n = 6) and medical air pneumoperitoneum (n = 6).

RESULTS

Renal PO(2) was inversely related to the IAP (P < .001). Despite the reduction in IAP, the renal PO(2) in the recovery phase was lower than at baseline (P = .045). The renal PO(2) and RBF changed in a virtually identical pattern at varying levels of IAP (P > .05). The RBF significantly declined with a pneumoperitoneal pressure of 15 and 20 mm Hg (P = .022), regardless of the gas used to create the pneumoperitoneum. A partial reversal of the RBF occurred with a decrease of the IAP. The RBF in the open surgical arm remained unchanged. Although both the serum pH and the mean arterial pressure were inversely proportional to the IAP (P < .001), the mean arterial pressure was depressed to the greatest extent in the medical air group (P = .02).

CONCLUSIONS

These results have demonstrated that elevated IAP secondary to pneumoperitoneum causes significant renal hypoxia and decreased RBF. Additionally, this experiment has demonstrated the use of the Licox probes in monitoring the renal PO(2) and established a novel method for evaluating the effects of IAP on the kidney.

Hemolink, an o-raffinose cross-linked haemoglobin-based oxygen carrier, does not affect activation and function of human platelets in whole blood in vitro

Haemoglobin-based oxygen carriers (HBOCs) are anticipated to be safe and efficient alternatives to RBC transfusions. Haemoglobin (Hb) raffimer (Hemolink; Hemosol, Toronto, ON, Canada) is polymerized human Hb, cross-linked with o-raffinose. As administration of cell-free Hb may affect blood cells and tissues, this study was focused on evaluating effects of Hb raffimer on human platelets in whole blood in vitro. Citrated blood from healthy donors was incubated with Hb raffimer to achieve raffimer concentrations of 2-50 vol percentage (2-50 g/l). Platelet activation, phosphatidylserine exposure and microparticle generation were measured by flow cytometry. Aperture closure time on collagen/ADP- and collagen/epinephrine-coated membranes was determined by a platelet function analyser (PFA-100). We found that addition of Hb raffimer to blood samples up to 50 vol % did not affect human platelets as measured by various markers of platelet activation (CD42b, CD41, PAC-1, CD62, CD63), procoagulant activity (annexin V) and microparticle formation; differences between Hb raffimer- and lactated Ringer's-diluted blood were not significant. Similarly, no adverse effect of Hb raffimer on closure time was observed at concentrations up to 50 vol %, in comparison with Ringer's solution. These data indicate that exposure of human blood to high concentrations of Hb raffimer in vitro did not cause platelet activation nor affect platelet function.

Nutritional supplementation with MyoVive repletes essential cardiac myocyte nutrients and reduces left ventricular size in patients with left ventricular dysfunction

BACKGROUND

Congestive heart failure depletes the myocardium of carnitine, coenzyme Q10 (CoQ10), and taurine--substances known to influence mitochondrial function and cell calcium. We hypothesized that feeding patients a nutritional supplement that contained carnitine, CoQ10, and taurine would result in higher myocardial levels of these nutrients and improve left ventricular function.

METHODS

Forty-one patients who underwent aortocoronary artery bypass with an ejection fraction < or =40% at referral were randomly assigned to a double-blind trial of supplement or placebo. Radionuclide ventriculography was performed at randomization and before surgery. Surgical myocardial biopsies, adjusted for protein content, were analyzed for carnitine, CoQ10, and taurine levels.

RESULTS

The groups were well matched. Minor exceptions were supplement group versus placebo group for digoxin use (7 vs 0, respectively; P =.009) and age (62 +/- 11 years vs 69 +/- 5 years, respectively; P =.04). There were significantly higher levels in the treated group compared with the placebo group for myocardial levels of CoQ10 (138.17 +/- 39.87 nmol/g wet weight and 56.67 +/- 23.08 nmol/g wet weight; P =.0006), taurine (13.12 +/- 4.00 micromol/g wet weight and 7.91 +/- 2.81 micromol/g wet weight; P =.003), and carnitine (1735.4 +/- 798.5 nmol/g wet weight and 1237.6 +/- 343.1 nmol/g wet weight; P =.06). The left ventricular end-diastolic volume fell by -7.5 +/- 21.7 mL in the supplement group and increased by 10.0 +/- 19.8 mL in the placebo group (P =.037).

CONCLUSIONS

Supplementation results in higher myocardial CoQ10, taurine, and carnitine levels and is associated with a reduction in left ventricular end-diastolic volume in patients with left ventricular dysfunction before revascularization. Because the risk of death for surgical revascularization is related to preoperative left ventricular end-diastolic volume, supplementation could improve outcomes.

Concealed air leak associated with large tidal volumes in partial liquid ventilation

Current ventilator strategies aim at maintaining an open lung and limiting both peak inspiratory pressures and tidal volumes to avoid alveolar distension. Perfluorocarbons, as well as being excellent solvents for oxygen and carbon dioxide, have the unique properties of being able to recruit dependent lung regions and improve pulmonary mechanics. Optimal ventilator strategies for partial liquid ventilation (PLV) have not yet been clearly defined. In the surfactant-depleted rabbit model, an approach involving a large tidal volume (VT) (15 ml/kg) and lung filled to FRC with perfluorocarbon (PFC) was compared with strategies involving a moderate VT (9 ml/kg) and partially filled lung (6 ml/kg), a moderate VT (9 ml/kg) and lung filled to FRC with PFC, and a large VT (15 ml/kg) and partially filled lung (6 ml/kg). PEEP was maintained at 5 cm H2O except in the moderate VT, partial-filling group, in which a PEEP of 9 cm H2O was used to maintain the rabbits for the duration of the experiment. Oxygenation was satisfactory in all groups, and peak inspiratory pressures were not significantly different. However, five of the 13 animals in the large-VT, PFC-filled lung group died of a pneumothorax prior to completion of the experiment. Of the eight animals in this group surviving the experiment, two had radiographic evidence of pneumothoraces, with an additional three animals having autopsy evidence of air leak. Of the 22 animals in the other groups, all survived with the exception of a single rabbit in the large VT, partial-filling group, which had both radiographic and autopsy evidence of air leak. We conclude that there is a significant risk of barotrauma in a PLV strategy in which a large VT is used in association with a lung filled to FRC with perfluorocarbon. Adequate gas exchange can be achieved with alternative ventilation strategies in combination with PLV.