Nitrous oxide does not produce a clinically important sparing effect during closed-loop delivered propofol-remifentanil anaesthesia guided by the bispectral index: a randomized multicentre study†‡

Background Nitrous oxide (N2O) offers both hypnotic and analgesic characteristics. We therefore tested the hypothesis that N2O administration decreases the amount of propofol and remifentanil given by a closed-loop automated controller to maintain a similar bispectral index (BIS). Methods In a randomized multicentre double-blind study, patients undergoing elective surgery were randomly assigned to breathe 60% inspired N2O (N2O group) or 40% oxygen (AIR group). Anaesthesia depth was evaluated by the proportion of time where BIS was within the range of 40-60 (BIS40-60). The primary outcomes were propofol and remifentanil consumption, with reductions of 20% in either being considered clinically important. Results A total of 302 patients were randomized to the N2O group and 299 to the AIR group. At similar BIS40-60 [79 (67-86)% vs 76 (65-85)%], N2O slightly decreased propofol consumption [4.5 (3.7-5.5) vs 4.8 (4.0-5.9) mg kg−1 h−1, P=0.032], but not remifentanil consumption [0.17 (0.12-0.23) vs 0.18 (0.14-0.24) µg kg−1 min−1]. For the subgroups of men, at similar BIS40-60 [80 (72-88)% vs 80 (70-87)%], propofol [4.2 (3.4-5.3) vs 4.4 (3.6-5.4) mg kg−1 h−1] and remifentanil [0.19 (0.13-0.25) vs 0.18 (0.15-0.23) µg kg−1 min−1] consumptions were similar in the N2O vs AIR group, respectively. For the subgroups of women, at similar BIS40-60 [76 (64-84)% vs 72 (62-82)%], propofol [4.7 (4.0-5.8) vs 5.3 (4.5-6.6) mg kg−1 h−1, P=0.004] and remifentanil [0.18 (0.13-0.25) vs 0.20 (0.15-0.27) µg kg−1 min−1, P=0.029] consumptions decreased with the co-administration of N2O. Conclusions With automated drug administration titrated to comparable BIS, N2O only slightly reduced propofol consumption and did not reduce remifentanil consumption. There was a minor gender dependence, but not by a clinically important amount. Clinical trial registration This study was registered at ClinicalTrials.gov, number NCT0054720

Rationale and design of the PeriOperative ISchemic Evaluation-3 (POISE-3) : a randomized controlled trial evaluating tranexamic acid and a strategy to minimize hypotension in noncardiac surgery

Altres ajuts: Canadian Institutes of Health Research (CIHR, FDN-143302); General Research Fund (14104419), Research Grant Council, Hong Kong SAR, China; National Health and Medical Research Council, Funding Schemes (NHMRC Project Grant 1162362), Australia; McMaster University Department of Medicine Career Research Award and a Physicians' Services Incorporated (PSI) Foundation Mid-Career Clinical Research Award.Background: For patients undergoing noncardiac surgery, bleeding and hypotension are frequent and associated with increased mortality and cardiovascular complications. Tranexamic acid (TXA) is an antifibrinolytic agent with the potential to reduce surgical bleeding; however, there is uncertainty about its efficacy and safety in noncardiac surgery. Although usual perioperative care is commonly consistent with a hypertension-avoidance strategy (i.e., most patients continue their antihypertensive medications throughout the perioperative period and intraoperative mean arterial pressures of 60 mmHg are commonly accepted), a hypotension-avoidance strategy may improve perioperative outcomes. Methods: The PeriOperative Ischemic Evaluation (POISE)-3 Trial is a large international randomized controlled trial designed to determine if TXA is superior to placebo for the composite outcome of life-threatening, major, and critical organ bleeding, and non-inferior to placebo for the occurrence of major arterial and venous thrombotic events, at 30 days after randomization. Using a partial factorial design, POISE-3 will additionally determine the effect of a hypotension-avoidance strategy versus a hypertension-avoidance strategy on the risk of major cardiovascular events, at 30 days after randomization. The target sample size is 10,000 participants. Patients ≥45 years of age undergoing noncardiac surgery, with or at risk of cardiovascular and bleeding complications, are randomized to receive a TXA 1 g intravenous bolus or matching placebo at the start and at the end of surgery. Patients, health care providers, data collectors, outcome adjudicators, and investigators are blinded to the treatment allocation. Patients on ≥ 1 chronic antihypertensive medication are also randomized to either of the two blood pressure management strategies, which differ in the management of patient antihypertensive medications on the morning of surgery and on the first 2 days after surgery, and in the target mean arterial pressure during surgery. Outcome adjudicators are blinded to the blood pressure treatment allocation. Patients are followed up at 30 days and 1 year after randomization. Discussion: Bleeding and hypotension in noncardiac surgery are common and have a substantial impact on patient prognosis. The POISE-3 trial will evaluate two interventions to determine their impact on bleeding, cardiovascular complications, and mortality. Trial registration: ClinicalTrials.gov NCT03505723. Registered on 23 April 2018

Measurement of muscle stiffness using robotic assisted gait orthosis in children with cerebral palsy: a proof of concept

Purpose. To evaluate the feasibility and reliability of a novel stiffness assessment tool implemented in the driven gait orthosis Paediatric Lokomat; to investigate the influence of single robotic-assisted gait training (RAGT) on muscle stiffness in children with cerebral palsy (CP). Methods. Ten children with spastic CP conducted a single standard RAGT session and stiffness was assessed before and after the RAGT. Nine of the ten subjects were tested twice on the same day to investigate test-retest reliability, intraclass correlation coefficients (ICCs), standard error of measurement (SEM), coefficient of variation of the method error (CV(ME)) and resistive torques during passive leg movements (stiffness in Nm/ degrees ) were calculated. Results. ICCs showed high reliability (0.83-0.97) for hip and knee movements. SEM and CV(ME) indicated 0.028-0.085 Nm/ degrees , 9.5-23.0% of test-retest variability in hip and 0.018-0.064 Nm/ degrees , 13.3-43.5% in knee measures. Using the assessment tool, a significant decrease in muscle stiffness in participants, especially in children with high levels of muscle tone, could be shown after a single session of RAGT. Conclusions. The assessment tool L-STIFF is a feasible tool for automated measurement of stiffness in children with CP, but it is not sensitive enough to record small changes in muscle tone

Does a balanced colloid decrease perioperative blood loss in paediatric cardiac surgery

BACKGROUND Unbalanced fluid solutions cause metabolic acidosis and could be associated with impaired coagulation and increased blood loss. OBJECTIVE To investigate whether the use of a balanced colloid compared with a saline colloid for peri-operative fluid therapy in children undergoing cardiac surgery is associated with decreased blood loss and exposure to blood products. DESIGN Double-blinded randomised controlled trial. SETTING Tertiary children's hospital from 2013 to 2016. PATIENTS Children older than 29 days and younger than 3 years admitted for cardiac surgery with cardiopulmonary bypass (CPB). Exclusion criteria were emergency cardiac surgery, moribund (American Society of Anesthesiologists 5), Jehovah's witnesses, coagulopathy, renal failure, liver injury, intracranial haemorrhage and electrolyte disturbances. From the 128 patients eligible, 88 were included in the study. INTERVENTION Random assignment of patients to either a saline colloid (6% hydroxyethyl starch 130/0.4 in 0.9% NaCl) or a balanced-electrolyte colloid (6% hydroxyethyl starch 130/0.4 in an isotonic solution) for CPB priming and intra- and postoperative fluid therapy during the first postoperative 48 h. MAIN OUTCOME MEASURE The primary outcome measure was calculated blood loss until the third postoperative day (POD3). RESULTS A total of 44 patients were included in each study arm. Calculated blood loss at POD3 was not significantly different between the groups (saline colloid 19.9 [IQR 13.8 to 26.1] ml kg(-1) versus balanced colloid 15.9 [IQR 9.0 to 25.3 ml kg(-1)], P = 0.409). Secondary outcomes related to bleeding, exposure to blood products and coagulation were not different between groups. There was also no difference in length of mechanical ventilation, intensive care and hospital length of stay between groups. CONCLUSION The use of a balanced colloid for peri-operative fluid therapy compared with a saline one is not associated with decreased blood loss or exposure to blood products.Perioperative Medicine: Efficacy, Safety and Outcome (Anesthesiology/Intensive Care

Does a balanced colloid decrease perioperative blood loss in paediatric cardiac surgery A double-blinded randomized controlled trial?

BACKGROUND Unbalanced fluid solutions cause metabolic acidosis and could be associated with impaired coagulation and increased blood loss. OBJECTIVE To investigate whether the use of a balanced colloid compared with a saline colloid for peri-operative fluid therapy in children undergoing cardiac surgery is associated with decreased blood loss and exposure to blood products. DESIGN Double-blinded randomised controlled trial. SETTING Tertiary children's hospital from 2013 to 2016. PATIENTS Children older than 29 days and younger than 3 years admitted for cardiac surgery with cardiopulmonary bypass (CPB). Exclusion criteria were emergency cardiac surgery, moribund (American Society of Anesthesiologists 5), Jehovah's witnesses, coagulopathy, renal failure, liver injury, intracranial haemorrhage and electrolyte disturbances. From the 128 patients eligible, 88 were included in the study. INTERVENTION Random assignment of patients to either a saline colloid (6% hydroxyethyl starch 130/0.4 in 0.9% NaCl) or a balanced-electrolyte colloid (6% hydroxyethyl starch 130/0.4 in an isotonic solution) for CPB priming and intra- and postoperative fluid therapy during the first postoperative 48 h. MAIN OUTCOME MEASURE The primary outcome measure was calculated blood loss until the third postoperative day (POD3). RESULTS A total of 44 patients were included in each study arm. Calculated blood loss at POD3 was not significantly different between the groups (saline colloid 19.9 [IQR 13.8 to 26.1] ml kg(-1) versus balanced colloid 15.9 [IQR 9.0 to 25.3 ml kg(-1)], P = 0.409). Secondary outcomes related to bleeding, exposure to blood products and coagulation were not different between groups. There was also no difference in length of mechanical ventilation, intensive care and hospital length of stay between groups. CONCLUSION The use of a balanced colloid for peri-operative fluid therapy compared with a saline one is not associated with decreased blood loss or exposure to blood products.Perioperative Medicine: Efficacy, Safety and Outcome (Anesthesiology/Intensive Care