Effects of wearing surgical masks on fraction of inspired oxygen in spontaneously breathing patients: improving safety for frontline healthcare professionals under pandemic situations.

BACKGROUND: During pandemic situations, many guidelines recommend that surgical masks be worn by both healthcare professionals and infected patients in healthcare settings. The purpose of this study was to clarify the levels and changes of oxygen concentration over time while oxygen was administered over a surgical mask. METHODS: Patients scheduled to undergo general anesthesia (n = 99) were enrolled in this study. First, patients were administered oxygen at 6 L/min via an oxygen mask over a surgical mask for 5 min. The patients removed the surgical mask and then took a 3-min break; thereafter, the same amount of oxygen was administered for another 5 min via the oxygen mask. We measured the fraction of inspired oxygen (FiO2), the end-tidal CO2 (EtCO2), and respiratory frequency every minute for 5 min, both while administering oxygen with and without a surgical mask. The FiO2 was measured at the beginning of inspiration and the EtCO2 was measured at the end of expiration. RESULTS: The FiO2 at 5 min was significantly lower when breathing with a surgical mask than that without it (mean difference: 0.08 [95% CI: 0.067-0.10]; p <  0.001). In contrast, the EtCO2 at 5 min was significantly higher when breathing with a surgical mask than that without it (mean difference: 11.9 mmHg [95% CI: 10.9-12.9]; p <  0.001). CONCLUSION: The FiO2 was lower when oxygen was administered over surgical masks than when patients did not wear surgical masks. Oxygen flow may need to be adjusted in moderately ill patients requiring oxygen administration.

Impact of anesthetic agents on the amount of bleeding during dilatation and evacuation: A systematic review and meta-analysis.

PURPOSE: Patients undergo dilatation and evacuation for abortion or miscarriage. However, bleeding is sometimes problematic. Despite reports on the association between volatile anesthetics and increased bleeding during the procedure, firm evidence is lacking. Therefore, we conducted a systematic review and meta-analysis to compare the effects of volatile anesthetics and propofol on the amount of bleeding in patients undergoing dilatation and evacuation. METHODS: We conducted a systematic search of four databases, namely PubMed, Embase, Cochrane Central Register of Controlled Trials databases, and Web of Science (Clarivate Analytics), from their respective inception to April 2021. Moreover, we searched two trial registration sites. The inclusion criterion was randomized controlled trials of patients who underwent dilatation and evacuation under general anesthesia using volatile anesthetics or propofol. The primary outcome was the amount of perioperative bleeding. The mean difference of the bleeding was combined using a random-effects model. The I2 statistic was used to assess heterogeneity. We assessed risk of bias with Cochrane domains. We controlled type I and II errors due to sparse data and repetitive testing with Trial Sequential Analysis. We assessed the quality of evidence with GRADE. RESULTS: Five studies were included in the systematic review. The amount of bleeding was compared in four studies and was higher in the volatile anesthetic group, with a mean difference of 164.7 ml (95% confidence interval, 43.6 to 285.7; p = 0.04). Heterogeneity was considerable, with an I2 value of 97%. Two studies evaluated the incidence of significant bleeding, which was significantly higher in the volatile anesthetic group (RR, 2.42; 95% confidence interval, 1.04-5.63; p = 0.04). CONCLUSION: Choosing propofol over volatile anesthetics during dilatation and evacuation might reduce bleeding and the incidence of excessive bleeding. However, the quality of the evidence was very low. This necessitates further trials with a low risk of bias. TRIAL REGISTRATION: PROSPERO (CRD42019120873).

Effectiveness of intravenous lidocaine in preventing postoperative nausea and vomiting in pediatric patients: A systematic review and meta-analysis.

BACKGROUND: Intravenous lidocaine in adults undergoing general anesthesia has been shown to reduce the incidence of postoperative nausea and vomiting (PONV). However, the anti-postoperative vomiting (POV) effect of lidocaine in pediatric patients remains unclear. We conducted a systematic review and meta-analysis with Trial Sequential Analysis to evaluate the effect of intravenous lidocaine on prevention of POV/PONV. METHODS: Six databases including trial registration sites were searched. Randomized clinical trials evaluating the incidence of POV/PONV after intravenous lidocaine compared with control were included. The primary outcome was the incidence of POV within 24 hours after general anesthesia. The incidence of POV was combined as a risk ratio with 95% confidence interval using a random-effect model. We used the I2 to assess heterogeneity. We evaluated the quality of trials using the Cochrane methodology, and we assessed quality of evidence using the Grading of Recommendation Assessment, Development, and Evaluation approach. We also assessed adverse events. RESULTS AND DISCUSSION: Six trials with 849 patients were included, of whom 433 received intravenous lidocaine. Three trials evaluated the incidence of POV, and 3 evaluated the incidence of PONV. The overall incidence of POV within 24 hours after anesthesia was 45.9% in the lidocaine group and 63.4% in the control group (risk ratio, 0.73; 95% confidence interval, 0.53-1.00; I2 = 32%; p = 0.05). The incidence of PONV within 24 hours after anesthesia was 3.73% in the lidocaine group and 4.87% in the control group (RR, 0.76; 95% CI, 0.36-1.59; I2 = 0%; p = 0.47). The quality of evidence was downgraded to "very low" due to the study designs, inconsistency, imprecision, and possible publication bias. CONCLUSION: Our meta-analysis suggests that intravenous lidocaine infusion may reduce the incidence of POV, however, the evidence quality was "very low." Further trials with a low risk of bias are necessary.

Effectiveness of Magnesium in Preventing Shivering in Surgical Patients: A Systematic Review and Meta-analysis.

BACKGROUND: Clinical trials regarding the antishivering effect of perioperative magnesium have produced inconsistent results. We conducted a systematic review and meta-analysis with Trial Sequential Analysis to evaluate the effect of perioperative magnesium on prevention of shivering. METHODS: We searched PubMed, EMBASE, Web of Science, Cochrane Central Register of Controlled Trials, and 2 registry sites for randomized clinical trials that compared the administration of magnesium to a placebo or no treatment in patients undergoing surgeries. The primary outcome of this meta-analysis was the incidence of shivering. The incidence of shivering was combined as a risk ratio with 95% CI using a random-effect model. The effect of the route of administration was evaluated in a subgroup analysis, and Trial Sequential Analysis with a risk of type 1 error of 5% and power of 90% was performed. The quality of each included trial was evaluated, and the quality of evidence was assessed using the Grading of Recommendation Assessment, Development, and Evaluation approach. We also assessed adverse events. RESULTS: Sixty-four trials and 4303 patients (2300 and 2003 patients in magnesium and control groups, respectively) were included. The overall incidence of shivering was 9.9% in the magnesium group and 23.0% in the control group (risk ratio, 0.42; 95% CI, 0.33-0.52). Subgroup analysis revealed that the incidence of shivering was lower with IV (risk ratio, 0.29; 95% CI, 0.29-0.54; Grading of Recommendation Assessment, Development, and Evaluation, moderate), epidural (risk ratio, 0.24; 95% CI, 0.13-0.43; Grading of Recommendation Assessment, Development, and Evaluation, low), and intrathecal administration (risk ratio, 0.64; 95% CI, 0.43-0.96; Grading of Recommendation Assessment, Development, and Evaluation, moderate). Only trials with low risk of bias were included for Trial Sequential Analysis. The Z-cumulative curve for IV magnesium crossed the Trial Sequential Analysis monitoring boundary for benefit even though only 34.9% of the target sample size had been reached. The Z-cumulative curve for epidural or intrathecal administration did not cross the Trial Sequential Analysis monitoring boundary for benefit. No increase in adverse events was reported. CONCLUSIONS: Perioperative IV administration of magnesium effectively reduced shivering and Trial Sequential Analysis suggested that no more trials are required to confirm that IV magnesium effectively reduces shivering.

Behavior of Anesthesiology Residents in a Situation of Intravenous Route Occlusion During Syringe Pump Use in a Simulated Intensive Care Unit.

INTRODUCTION: Unintentional catecholamine flush caused by inappropriate release of an intravenous occlusion during use of a syringe pump in the intensive care unit (ICU) can have dangerous consequences in patients receiving critical care. We investigated whether anesthesiology residents understood how to deal with syringe pump occlusion in a simulated ICU setting. METHODS: We set up a mannequin that virtually simulated a sedated patient under mechanical ventilation after cardiac surgery, with epinephrine and dopamine being infused by syringe pumps to maintain blood pressure at 100/50 mm Hg. Prior to a participant entering the simulated ICU, one of the stopcocks for the catecholamine was occluded. Thereafter, the blood pressure of the mannequin dropped to 60/30 mm Hg. If the participant inappropriately released the occlusion, resulting in a catecholamine flush, an operator immediately elevated the blood pressure to 200/100 mm Hg. In the subsequent debriefing session, the simulation facilitator evaluated whether the participant could diagnose that intravenous occlusion was the cause of hypotension in this scenario. RESULTS: Sixteen anesthesiology residents participated in the study. Only 3 of 10 participants who had previous knowledge of how such situations should be handled could appropriately release back pressure. Eleven residents released the occlusion without relieving syringe pressure. After their debriefing sessions, all the participants were of the opinion that the present simulation training was impressive and useful for them. CONCLUSIONS: Anesthesiology residents might inappropriately handle a situation of intravenous occlusion in their clinical practice. It may be necessary for the manufacturers to improve the safety features of syringe pumps.

Effect of magnesium added to local anesthetics for caudal anesthesia on postoperative pain in pediatric surgical patients: A systematic review and meta-analysis with Trial Sequential Analysis.

BACKGROUND: Magnesium has been investigated as an adjuvant for neuraxial anesthesia, but the effect of caudal magnesium on postoperative pain is inconsistent. The aim of this systematic review and meta-analysis was to evaluate the analgesic effect of caudal magnesium. METHODS: We searched six databases, including trial registration sites. Randomized clinical trials reporting the effect of caudal magnesium on postoperative pain after general anesthesia were eligible. The risk ratio for use of rescue analgesics after surgery was combined using a random-effects model. We also assessed adverse events. The I2 statistic was used to assess heterogeneity. We assessed risk of bias with Cochrane domains. We controlled type I and II errors due to sparse data and repetitive testing with Trial Sequential Analysis. We assessed the quality of evidence with GRADE. RESULTS: Four randomized controlled trials (247 patients) evaluated the need for rescue analgesics. In all four trials, 50 mg of magnesium was administered with caudal ropivacaine. The results suggested that the need for rescue analgesia was reduced significantly by caudal magnesium administration (risk ratio 0.45; 95% confidence interval 0.24-0.86). There was considerable heterogeneity as indicated by an I2 value of 62.5%. The Trial Sequential Analysis-adjusted confidence interval was 0.04-5.55, indicating that further trials are required. The quality of evidence was very low. The rate of adverse events was comparable between treatment groups. CONCLUSION: Caudal magnesium may reduce the need for rescue analgesia after surgery, but further randomized clinical trials with a low risk of bias and a low risk of random errors are necessary to assess the effect of caudal magnesium on postoperative pain and adverse events. TRIAL REGISTRATION: University Hospital Medical Information Network Clinical Trials Registry UMIN000025344.

Effect of an Intravenous Dexamethasone Added to Caudal Local Anesthetics to Improve Postoperative Pain: A Systematic Review and Meta-analysis With Trial Sequential Analysis.

BACKGROUND: Caudal anesthesia has been used for postoperative pain control in pediatric surgical patients, but the duration of the analgesic effect is occasionally unsatisfactory. Intravenous steroids have been shown to be effective for postsurgical pain management after certain surgeries. The aim of this meta-analysis with trial sequential analysis (TSA) was to evaluate the analgesic effect of steroids in patients administered with caudal anesthesia. METHODS: This study was a systematic review and meta-analysis. A search of published literature was conducted in the MEDLINE, EMBASE, Web of Science, and Cochrane Central Register of Controlled Trials databases and in trial registration sites. Randomized controlled trials that compared intravenous steroids with a placebo in pediatric patients who had received caudal anesthesia for surgery were included in the study. The primary outcomes from the present meta-analysis were the analgesic duration and the number of patients who required rescue analgesics. The analgesic duration and incidence of rescue use were summarized using mean difference or risk ratio with a 97.5% confidence interval (CI), respectively. If the 97.5% CI of the mean difference or risk ratio included a value of 0 or 1, respectively, we considered the difference not to be significant. We used the random effects model to combine the results. Heterogeneity was quantified with the I statistic. The quality of the trials was evaluated using the Cochrane methodology. Moreover, a TSA with a risk of type 1 error of 2.5% and power of 90% was performed. We established the minimum clinically meaningful difference of analgesic duration as 3 hours. The target sample size for meta-analysis was also calculated in the TSA. We also assessed adverse events. RESULTS: Six trials with 424 patients were included; 211 patients received intravenous steroids. All trials compared dexamethasone of at least 0.5 mg/kg dose with a placebo. Dexamethasone prolonged the duration of caudal analgesia (mean difference, 244 minutes; 97.5% CI, 188-300). Heterogeneity was considerable with an I value of 94.8%. Quality of evidence was very low. The TSA suggested that only 17.0% of the target sample size had been reached, but the cumulative Z score crossed the trial sequential monitoring boundary to indicate a benefit. Rescue use was reported in 4 studies with 260 patients. Rescue use was not significantly reduced in the dexamethasone group (risk ratio, 0.53; 97.5% CI, 0.09-3.30; I, 98.7%). No increase in adverse events was reported. CONCLUSIONS: Intravenous dexamethasone prolongs the analgesic duration of caudal anesthesia. Trials to investigate the effectiveness of a lower dose of the dexamethasone in prolonging analgesic effects would be of interest. Further trials with a low risk of bias are necessary.

Consequences of not relieving negative internal pressure of a medication vial: A survey and simulation study.

STUDY OBJECTIVE: The glass vial of acetaminophen as an intravenous preparation (Acelio®, Terumo, Japan) has a strong internal negative pressure. The aim of our study was to determine if this negative pressure could result in medication administration errors if not released prior to connecting to the IV set. DESIGN: Questionnaire survey and simulation study. SETTING: University hospital and its affiliated hospitals. SUBJECTS: Fifty-two anesthesiologists in 6 different hospitals in Yokohama. MEASUREMENTS: A questionnaire on current practice was sent to the subjects. The authors then first calculated the internal pressure of the Acelio® vial followed by a simulation set-up. This set-up measured the amount of saline that could be aspirated from a syringe loaded on a syringe pump connected via a secondary IV line when the Acelio® vial was attached to the primary line without prior release of the internal pressure. The volume of aspiration was tested with two syringe sizes and with a fully open IV clamp vs partially closed. MAIN RESULTS: Twenty-nine (56.9%) of 51 anesthesiologists who responded to the survey had connected the Acelio® vial at least once without releasing the internal negative pressure, and 21 experienced consequences such as backflow of the venous blood. The pressure inside the Acelio® vial was 81.8±19.6Torr. With the clamp of the simulated IV line fully open, the amount of saline aspirated before the alarm of the syringe pump went off was 1.5±0.1ml and 3.2±0.3ml when 20ml and 50ml syringes were used, respectively. When the clamp was partially closed to allow 2 drops per second, this value was 1.3±0.1ml and 2.3±0.1ml, respectively. After removing the plunger from the holder of the syringe pump, an additional 7ml (clamp partially closed) or 15-18ml (clamp fully open) was aspirated in the subsequent 1min. CONCLUSIONS: A considerable number of anesthesiologists experienced consequences caused by the negative pressure inside the Acelio® vial. This can also cause aspiration of the contents of the syringe pump.

Influence of Mental Workload on the Performance of Anesthesiologists during Induction of General Anesthesia: A Patient Simulator Study.

The aim of this study was to reveal the effect of anesthesiologist's mental workload during induction of general anesthesia. Twenty-two participants were categorized into anesthesiology residents (RA group, n = 13) and board certified anesthesiologists (CA group, n = 9). Subjects participated in three simulated scenarios (scenario A: baseline, scenario B: simple addition tasks, and scenario C: combination of simple addition tasks and treatment of unexpected arrhythmia). We used simple two-digit integer additions every 5 seconds as a secondary task. Four kinds of key actions were also evaluated in each scenario. In scenario C, the correct answer rate was significantly higher in the CA versus the RA group (RA: 0.370 ± 0.050 versus CA: 0.736 ± 0.051, p < 0.01, 95% CI -0.518 to -0.215) as was the score of key actions (RA: 2.7 ± 1.3 versus CA: 4.0 ± 0.00, p = 0.005). In a serious clinical situation, anesthesiologists might not be able to adequately perform both the primary and secondary tasks. This tendency is more apparent in young anesthesiologists.

Role of VPAC2 receptor in monocrotaline-induced pulmonary hypertension in rats.

Pulmonary hypertension (PH) is associated with significant morbidity and mortality. Vasoactive intestinal peptide (VIP) and pituitary adenylyl cyclase activating peptide (PACAP) have pulmonary vasodilatory and positive inotropic effects via receptors VPAC1 and VPAC2, which possess a similar affinity for both peptides, and PAC1, a PACAP-preferring receptor. VIP is a promising option for PH treatment; however, various physiological effects of VIP have limited its clinical use. We investigated the effects of VPAC1 and VPAC2 selective agonists VIP and PACAP to explore more appropriate means of treatment for PH. We examined hemodynamic changes in right ventricular systolic pressure (RVSP), systemic blood pressure (SBP), total pulmonary resistance index (TPRI), total systemic resistance index, and cardiac index (CI) in response to their agonists with monocrotaline (MCT)-induced PH and explored involvement of VIP/PACAP expression and receptors in PH. Sprague-Dawley rats were divided into the MCT group (administered MCT 60 mg/kg) and control group. In MCT-induced PH, decreased VIP and PACAP were associated with upregulation of VPAC1, VPAC2, and PAC1 in lung tissues. Intravenous injection of VPAC2-selective agonist BAY 55-9837 and VIP, but not [Ala(11,22,28)]VIP, improved the CI. The decrease in SBP with VPAC2 agonist was significantly less than that in the control. Although they decreased SBP, these agonists hardly affected RVSP in the control. Activation of VPAC2 receptor with BAY 55-9837 effectively improved RVSP, TPRI, and CI in MCT-induced PH, suggesting a VPAC2 agonist as a possible promising treatment for PH.

Amount of accidental flush by syringe pump due to inappropriate release of occluded intravenous line.

BACKGROUND: An unintended bolus is delivered by the syringe pump if intravenous line occlusion is released in an inappropriate manner. OBJECTIVE: The aim of this study was to measure the amount of flushed fluid when an occlusion is inappropriately released and to assess the effect of different syringe pump settings (flow rate, alarm setting, size of syringe and syringe pump model) on the flushed amount. METHODS: After the stopcock was closed, infusions were started with different model syringe pumps (Terufusion® TE312 and TE332S), different syringe sizes or at different alarm settings. After the occlusion alarm sounded, the occlusion was released and the amount of fluid emerging from the stopcock was measured. RESULTS: The bolus was significantly lower when the alarm was set at a low-pressure setting. The bolus was significantly lower with a 10-ml than a 50-ml syringe. A significant difference was seen only when a 50-ml syringe was used (TE312: 1.99 ± 0.16 ml vs. TE332S: 0.674 ± 0.116 ml, alarm High, p < 0.001). CONCLUSION: To minimize the amount of accidentally injected medication, a smaller syringe size and a low alarm setting are important. Using a syringe pump capable of reducing the inadvertently administered bolus may be helpful.

Hypertension and anesthesia.

PURPOSE OF REVIEW: There are still many controversies about perioperative management of hypertensive patients. This review aims to provide relevant instruction based on evidence regarding the treatment of those patients. RECENT FINDINGS: Mild to moderate hypertension is not independently responsible for perioperative cardiac complications. The position is less clear for severely hypertensive patients. A randomized study shows no benefit of the traditional practice of delaying elective surgery in severely hypertensive patients until better control of blood pressure is achieved. Perioperative use of beta-blockers or alpha-2 agonists has been shown to maintain perioperative hemodynamic stability and thereby to prevent major cardiac complications. SUMMARY: Delaying surgery only for the purpose of blood pressure control may not be necessary, especially in the case of mild to moderate hypertension. Strict care, however, should be taken to ensure perioperative hemodynamic stability because labile hemodynamics, rather than preoperative hypertension per se, appears to be more closely associated with adverse cardiovascular complications. Delaying surgery in hypertensive patients may be justified if target organ damage exists that can be improved by such a delay or if (suspected) target organ damage should be evaluated further before the operation.