Effects of Volatile Anesthetic Choice on Hospital Length-of-stay

Optimizing accrual to a large-scale, clinically integrated randomized trial in anesthesiology: A 2-year analysis of recruitment

BACKGROUND

Performing large randomized trials in anesthesiology is often challenging and costly. The clinically integrated randomized trial is characterized by simplified logistics embedded into routine clinical practice, enabling ease and efficiency of recruitment, offering an opportunity for clinicians to conduct large, high-quality randomized trials under low cost. Our aims were to (1) demonstrate the feasibility of the clinically integrated trial design in a high-volume anesthesiology practice and (2) assess whether trial quality improvement interventions led to more balanced accrual among study arms and improved trial compliance over time.

METHODS

This is an interim analysis of recruitment to a cluster-randomized trial investigating three nerve block approaches for mastectomy with immediate implant-based reconstruction: paravertebral block (arm 1), paravertebral plus interpectoral plane blocks (arm 2), and serratus anterior plane plus interpectoral plane blocks (arm 3). We monitored accrual and consent rates, clinician compliance with the randomized treatment, and availability of outcome data. Assessment after the initial year of implementation showed a slight imbalance in study arms suggesting areas for improvement in trial compliance. Specific improvement interventions included increasing the frequency of communication with the consenting staff and providing direct feedback to clinician investigators about their individual recruitment patterns. We assessed overall accrual rates and tested for differences in accrual, consent, and compliance rates pre- and post-improvement interventions.

RESULTS

Overall recruitment was extremely high, accruing close to 90% of the eligible population. In the pre-intervention period, there was evidence of bias in the proportion of patients being accrued and receiving the monthly block, with higher rates in arm 3 (90%) compared to arms 1 (81%) and 2 (79%, p = 0.021). In contrast, in the post-intervention period, there was no statistically significant difference between groups (p = 0.8). Eligible for randomization rate increased from 89% in the pre-intervention period to 95% in the post-intervention period (difference 5.7%; 95% confidence interval = 2.2%-9.4%, p = 0.002). Consent rate increased from 95% to 98% (difference of 3.7%; 95% confidence interval = 1.1%-6.3%; p = 0.004). Compliance with the randomized nerve block approach was maintained at close to 100% and availability of primary outcome data was 100%.

CONCLUSION

The clinically integrated randomized trial design enables rapid trial accrual with a high participant compliance rate in a high-volume anesthesiology practice. Continuous monitoring of accrual, consent, and compliance rates is necessary to maintain and improve trial conduct and reduce potential biases. This trial methodology serves as a template for the implementation of other large, low-cost randomized trials in anesthesiology.

Pragmatic Comparative Effectiveness Trials and Learning Health Systems in Pain Medicine: Opportunities and Challenges

Large randomized clinical trials or aggregates of clinical trials represent the highest levels of clinical evidence because they minimize different sources of confounding and bias. The current review provides an in-depth discussion of the challenges faced and methods we can use to overcome these obstacles to tailor novel designs of pragmatic effectiveness trials to pain medicine. The authors describe their experiences with an open-source learning health system to collect high-quality evidence and conduct pragmatic clinical trials within a busy academic pain center.

Intraoperative Inspiratory Oxygen Fraction and Myocardial Injury After Noncardiac Surgery: Results From an International Observational Study in Relation to Recent Controlled Trials

BACKGROUND

Two trials reported that a high inspiratory oxygen fraction (F io2 ) does not promote myocardial infarction or death. Observational studies can provide larger statistical strength, but associations can be due to unobserved confounding. Therefore, we evaluated the association between intraoperative F io2 and cardiovascular complications in a large international cohort study to see if spurious associations were observed.

METHODS

We included patients from the Vascular events In noncardiac Surgery patIents cOhort evaluatioN (VISION) study, who were ≥45 years of age, scheduled for overnight hospital admission, and had intraoperative F io2 recorded. The primary outcome was myocardial injury after noncardiac surgery (MINS), and secondary outcomes included mortality and pneumonia, all within 30 postoperative days. Data were analyzed with logistic regression, adjusted for many baseline cardiovascular risk factors, and illustrated in relation to findings from 2 recent controlled trials.

RESULTS

We included 6588 patients with mean age of 62 years of whom 49% had hypertension. The median intraoperative F io2 was 0.46 (5%-95% range, 0.32-0.94). There were 808 patients (12%) with MINS. Each 0.10 increase in median F io2 was associated with a confounder-adjusted increase in odds for MINS: odds ratio (OR), 1.17 (95% confidence interval [CI], 1.12-1.23; P < .0001). MINS occurred in contrast with similar frequencies and no significant difference in controlled trials (2240 patients, 194 events), in which patients were given 80% vs 30% oxygen. Mortality was 2.4% and was not significantly associated with a median F io2 (OR, 1.07; 95% CI, 0.97-1.19 per 0.10 increase; P = .18), and 2.9% of patients had pneumonia (OR, 1.05; 95% CI, 0.95-1.15 per 0.10 increase; P = .34).

CONCLUSIONS

We observed an association between intraoperative F io2 and risk of myocardial injury within 30 days after noncardiac surgery, which contrasts with recent controlled clinical trials. F io2 was not significantly associated with mortality or pneumonia. Unobserved confounding presumably contributed to the observed association between F io2 and myocardial injury that is not supported by trials.

International Policy Frameworks for Consent in Minimal-risk Pragmatic Trials

There is intense debate around the use of altered and waived consent for pragmatic trials. Those in favor argue that traditional consent compromises the internal and external validity of these trials. Those against, warn that the resultant loss of autonomy compromises respect for persons and could undermine trust in the research enterprise.This article examines whether international ethical guidelines and the policy frameworks in three countries-the United States, England, and Australia-permit altered and waived consent for minimal-risk pragmatic trials conducted outside the emergency setting. Provisions for both are clearly articulated in U.S. regulations, but many countries do not have equivalent frameworks. Investigators should not assume that all consent models permitted in the United States are legal in their jurisdictions, even if they are deemed ethically defensible.The authors summarize ethical and regulatory considerations and present a framework for investigators contemplating trials with altered or waived consent.

Long versus short dual antiplatelet therapy in acute coronary syndrome patients treated with prasugrel or ticagrelor and coronary revascularization: Insights from the RENAMI registry

Introduction

The benefits of short versus long-term dual antiplatelet therapy (DAPT) based on the third generation P2Y12 antagonists prasugrel or ticagrelor, in patients with acute coronary syndromes treated with percutaneous coronary intervention remain to be clearly defined due to current evidences limited to patients treated with clopidogrel.

Methods

All acute coronary syndrome patients from the REgistry of New Antiplatelets in patients with Myocardial Infarction (RENAMI) undergoing percutaneous coronary intervention and treated with aspirin, prasugrel or ticagrelor were stratified according to DAPT duration, that is, shorter than 12 months (D1 group), 12 months (D2 group) and longer than 12 months (D3 group). The three groups were compared before and after propensity score matching. Net adverse clinical events (NACEs), defined as a combination of major adverse cardiac events (MACEs) and major bleedings (including therefore all cause death, myocardial infarction and Bleeding Academic Research Consortium (BARC) 3–5 bleeding), were the primary end points, MACEs (a composite of all cause death and myocardial infarction) the secondary one. Single components of NACEs were co-secondary end points, along with BARC 2–5 bleeding, cardiovascular death and stent thrombosis.

Results

A total of 4424 patients from the RENAMI registry with available data on DAPT duration were included in the model. After propensity score matching, 628 patients from each group were selected. After 20 months of follow up, DAPT for 12 months and DAPT for longer than 12 months significantly reduced the risk of NACE (D1 11.6% vs. D2 6.7% vs. D3 7.2%, p = 0.003) and MACE (10% vs. 6.2% vs. 2.4%, p < 0.001) compared with DAPT for less than 12 months. These differences were driven by a reduced risk of all cause death (7.8% vs. 1.3% vs. 1.6%, p < 0.001), cardiovascular death (5.1% vs. 1.0% vs. 1.2%, p < 0.0001) and recurrent myocardial infarction (8.3% vs. 5.2% vs. 3.5%, p = 0.002). NACEs were lower with longer DAPT despite a higher risk of BARC 2–5 bleedings (4.6% vs. 5.7% vs. 6.2%, p = 0.04) and a trend towards a higher risk of BARC 3–5 bleedings (2.4% vs. 3.3% vs. 3.9%, p = 0.06). These results were not consistent for female patients and those older than 75 years old, due to an increased risk of bleedings which exceeded the reduction in myocardial infarction.

Conclusion

In unselected real world acute coronary syndrome patients treated with percutaneous coronary intervention, DAPT with prasugrel or ticagrelor prolonged beyond 12 months markedly reduces fatal and non-fatal ischaemic events, offsetting the increased risk deriving from the higher bleeding risk. On the contrary, patients >75 years old and female ones showed a less favourable risk–benefit ratio for longer DAPT due to excess of bleedings.

Novel Clinical Trial Designs to Improve the Efficiency of Research

SUMMARY

Large randomized trials provide the highest level of clinical evidence. However, enrolling large numbers of randomized patients across numerous study sites is expensive and often takes years. There will never be enough conventional clinical trials to address the important questions in medicine. Efficient alternatives to conventional randomized trials that preserve protections against bias and confounding are thus of considerable interest. A common feature of novel trial designs is that they are pragmatic and facilitate enrollment of large numbers of patients at modest cost. This article presents trial designs including cluster designs, real-time automated enrollment, and practitioner-preference approaches. Then various adaptive designs that improve trial efficiency are presented. And finally, the article discusses the advantages of embedding randomized trials within registries.

The Impact of Volatile Anesthetic Choice on Postoperative Outcomes of Cardiac Surgery: A Meta-Analysis

OBJECTIVES

To evaluate the impact of volatile anesthetic choice on clinically relevant outcomes of patients undergoing cardiac surgery.

METHODS

Major databases were systematically searched for randomized controlled trials (RCTs) comparing volatile anesthetics (isoflurane versus sevoflurane) in cardiac surgery. Study-level characteristics, intraoperative events, and postoperative outcomes were extracted from the articles.

RESULTS

Sixteen RCTs involving 961 patients were included in this meta-analysis. There were no significant differences between both anesthetics in terms of intensive care unit length of stay (SMD -0.07, 95% CI -0.38 to 0.24, P = 0.66), hospital length of stay (SMD 0.06, 95% CI -0.33 to 0.45, P = 0.76), time to extubation (SMD 0.29, 95% CI -0.08 to 0.65, P = 0.12), S100β (at the end of surgery: SMD 0.08, 95% CI -0.33 to 0.49, P = 0.71; 24 hours after surgery: SMD 0.21, 95% CI -0.23 to 0.65, P = 0.34), or troponin (at the end of surgery: SMD -1.13, 95% CI -2.39 to 0.13, P = 0.08; 24 hours after surgery: SMD 0.74, 95% CI -0.15 to 1.62, P = 0.10). CK-MB was shown to be significantly increased when using isoflurane instead of sevoflurane (SMD 2.16, 95% CI 0.57 to 3.74, P = 0.008).

CONCLUSIONS

The volatile anesthetic choice has no significant impact on postoperative outcomes of patients undergoing cardiac surgery.

Comparison of isoflurane and sevoflurane in cardiac surgery: a randomized non-inferiority comparative effectiveness trial

Purpose

Volatile anesthetics possess cardioprotective properties, but it is unknown if the cardioprotective effects extend equally to all members of the class. Although sevoflurane is a relatively newer anesthetic than isoflurane, its introduction into practice was not preceded by a head-to-head comparison with isoflurane in a trial focusing on clinically important outcomes. Our objective was to determine whether sevoflurane was non-inferior to isoflurane on a clinically important primary outcome in a heterogeneous group of adults undergoing cardiac surgery.

Methods

This was a pragmatic randomized non-inferiority comparative effectiveness clinical trial in 464 adults having coronary artery bypass graft and/or single valve surgery during November 2011 to March 2014. The intervention was maintenance of anesthesia with sevoflurane (n = 231) or isoflurane (n = 233) administered at a dose of 0.5-2.0 MAC throughout the entire operation. All caregivers were blinded except for the anesthesiologist and perfusionist. The primary outcome was a composite of intensive care unit (ICU) length of stay ≥ 48 hr and all-cause 30-day mortality. We hypothesized that sevoflurane would be non-inferior to isoflurane (non-inferiority margin < 10% based on an expected event rate of 25%). Secondary outcomes included prolonged ICU stay, 30- and 365-day all-cause mortality, inotrope or vasopressor usage, new-onset hemodialysis or atrial fibrillation, stroke, and readmission to the ICU.

Results

No losses to follow-up occurred. The primary outcome occurred in 25% of sevoflurane patients and 30% of isoflurane patients (absolute difference, −5.4%; one-sided 95% confidence interval, 1.4), thus non-inferiority was declared. Sevoflurane was not superior to isoflurane for the primary outcome (P = 0.21) or for any secondary outcomes.

Conclusion

Sevoflurane is non-inferior to isoflurane on a composite outcome of prolonged ICU stay and all-cause 30-day mortality. Sevoflurane is not superior to isoflurane on any other of the clinically important outcomes. This trial was registered at clinicaltrials.gov; NCT01477151.

Xenon does not increase heart rate-corrected cardiac QT interval in volunteers and in patients free of cardiovascular disease

BACKGROUND

Impaired cardiac repolarization, indicated by prolonged QT interval, may cause critical ventricular arrhythmias. Many anesthetics increase the QT interval by blockade of rapidly acting potassium rectifier channels. Although xenon does not affect these channels in isolated cardiomyocytes, the authors hypothesized that xenon increases the QT interval by direct and/or indirect sympathomimetic effects. Thus, the authors tested the hypothesis that xenon alters the heart rate-corrected cardiac QT (QTc) interval in anesthetic concentrations.

METHODS

The effect of xenon on the QTc interval was evaluated in eight healthy volunteers and in 35 patients undergoing abdominal or trauma surgery. The QTc interval was recorded on subjects in awake state, after their denitrogenation, and during xenon monoanesthesia (FetXe > 0.65). In patients, the QTc interval was recorded while awake, after anesthesia induction with propofol and remifentanil, and during steady state of xenon/remifentanil anesthesia (FetXe > 0.65). The QTc interval was determined from three consecutive cardiac intervals on electrocardiogram printouts in a blinded manner and corrected with Bazett formula.

RESULTS

In healthy volunteers, xenon did not alter the QTc interval (mean difference: +0.11 ms [95% CI, -22.4 to 22.7]). In patients, after anesthesia induction with propofol/remifentanil, no alteration of QTc interval was noted. After propofol was replaced with xenon, the QTc interval remained unaffected (417 ± 32 ms vs. awake: 414 ± 25 ms) with a mean difference of 4.4 ms (95% CI, -4.6 to 13.5).

CONCLUSION

Xenon monoanesthesia in healthy volunteers and xenon/remifentanil anesthesia in patients without clinically relevant cardiovascular disease do not increase QTc interval.

Evaluating NIR vascular imaging to support intravenous cannulation in awake children difficult to cannulate; a randomized clinical trial

BACKGROUND

Recently, various near-infrared vascular imaging devices aimed at facilitating peripheral intravenous cannulation (PIC) were introduced, all claiming to increase success rate of PIC. We evaluated the clinical utility of a near-infrared vascular imaging device (VascuLuminator(®)) in pediatric patients who were referred to the anesthesiologist because of difficult cannulation.

METHODS

There were 226 consecutive children referred to pediatric anesthesiologists by the treating pediatrician of the in- and outpatient clinic, because of difficulties with intravenous cannulation, were included in this cluster randomized clinical trial. The presence and use of the near-infrared vascular imaging device for PIC was randomized in clusters of 1 week. Success at first attempt (Fisher exact test) and time to successful cannulation (Log-rank test) were assessed to evaluate differences between groups.

RESULTS

Success at first attempt in the group with the VascuLuminator(®) (59%) was not significantly different from the control group (54%, P = 0.41), neither was the median time to successful cannulation: 246 s and 300 s, respectively (P = 0.54).

CONCLUSIONS

Visualization of blood vessels with near-infrared light and with near-infrared vascular imaging device did not improve success of PIC in pediatric patients who are known difficult to cannulate.