The Incidence and Predictors of Failed Spinal Anesthesia After Intrathecal Injection of Local Anesthetic for Cesarean Delivery: A Single-Center, 9-Year Retrospective Review.

BACKGROUND: The incidence of failed spinal anesthesia varies widely in the obstetric literature. Although many risk factors have been suggested, their relative predictive value is unknown. The primary objective of this retrospective cohort study was to determine the incidence of failed spinal anesthesia for cesarean deliveries at a tertiary care obstetric hospital, and its secondary objectives were to identify predictors of failed spinal anesthesia in the obstetrics population and quantify their relative importance in a predictive model for failure. METHODS: With local institutional ethics committee approval, a retrospective review of our hospital database identified the incidence of failed spinal anesthesia for 5361 cesarean deliveries between 2010 and 2019. We performed a multivariable analysis to assess the association of predictors with failure and a dominance analysis to assess the importance of each predictor. RESULTS: The incidence of failed spinal anesthesia requiring an alternative anesthetic was 2.1%, with conversion to general anesthesia occurring in 0.7% of surgeries. Supplemental analgesia or sedation was provided to an additional 2.0% of women. The most important predictors of a failed spinal anesthetic were previous cesarean delivery (odds ratio [OR], 11.33; 95% confidence interval [CI], 7.09-18.20; P < .001), concomitant tubal ligation (OR, 8.23; 95% CI, 3.12-19.20; P < .001), lower body mass index (BMI) (kg·m -2 , OR, 0.94; 95% CI, 0.90-0.98; P = .005), and longer surgery duration (minutes, OR, 1.02; 95% CI, 1.01-1.03; P = .006). Previous cesarean delivery was the most significant risk factor, contributing to 9.6% of the total 17% variance predicted by all predictors examined. CONCLUSIONS: Spinal anesthesia failed to provide a pain-free surgery in 4.1% of our cesarean deliveries. Previous cesarean delivery was the most important predictor of spinal failure. Other important predictors included tubal ligation, lower BMI, and longer surgery duration.

Efficacy of Intrathecal Fentanyl for Cesarean Delivery: A Systematic Review and Meta-analysis of Randomized Controlled Trials With Trial Sequential Analysis.

BACKGROUND: Fentanyl and morphine are the 2 most commonly added opioids to bupivacaine for spinal anesthesia during cesarean delivery. Numerous clinical trials have assessed efficacy and safety of different doses of fentanyl added to intrathecal bupivacaine for spinal anesthesia, yet its benefit, harm, and optimal dose remain unclear. This study aimed to systematically review the evidence of the efficacy of fentanyl when added to intrathecal bupivacaine alone and when added to bupivacaine with morphine for spinal anesthesia during cesarean delivery. METHODS: Key electronic databases (PubMed, Embase, and Cochrane Library) were searched for randomized controlled trials in the cesarean delivery population. The primary outcome was the failure rate of spinal anesthesia, as assessed by the need for either conversion to general anesthesia or intraoperative analgesic supplementation. Two reviewers independently extracted the data using a standardized electronic form. Results are expressed as relative risks or mean differences with 95% CIs. RESULTS: Seventeen randomized controlled clinical trials (most judged as low or unclear risk of bias) with 1064 participants provided data for the meta-analysis. Fentanyl added to intrathecal bupivacaine alone reduced the need for intraoperative supplemental analgesia (relative risk, 0.18; 95% CI, 0.11-0.27; number needed to treat, 4) and the incidence of nausea/vomiting (relative risk, 0.41; 95% CI, 0.24-0.70; number needed to treat, 6.5), with longer time to first postoperative analgesia request (mean difference, 91 minutes; 95% CI, 69-113). No difference was observed regarding the need for conversion to general anesthesia (relative risk, 0.67; 95% CI, 0.12-3.57), the incidence of hypotension, the onset of sensory block, or the duration of motor block. However, the addition of intrathecal fentanyl was associated with higher incidence of intraoperative pruritus (relative risk, 5.89; 95% CI, 2.07-16.79; number needed to harm, 13.5). The inclusion of fentanyl to intrathecal bupivacaine-morphine compared to intrathecal bupivacaine-morphine alone conferred a similar benefit, with a significantly reduced need for intraoperative supplemental analgesia (relative risk, 0.16; 95% CI, 0.03-0.95; number needed to treat, 9). Analysis using a funnel plot indicated a possibility of publication bias in included studies. CONCLUSIONS: Current evidence suggests a benefit of using fentanyl as both an additive to intrathecal bupivacaine alone and to intrathecal bupivacaine combined with morphine for cesarean delivery under spinal anesthesia. The possibility of publication bias, small sample size, and high risk of bias in some of the included studies warrant treating the results with caution.

Quadratus lumborum block for postoperative analgesia: a systematic review and meta-analysis.

PURPOSE: The goal of the present systematic review is to determine the efficacy of the quadratus lumborum block (QLB) in providing postoperative analgesia for abdominal wall and hip surgeries when compared with placebo or other analgesic techniques. METHODS: Electronic databases (Medline, Embase, Cochrane Central, and Scopus) were searched for keywords and controlled vocabulary terms related to QLB from their inception to November 2019. The included studies compared ultrasound-guided single-injection QLB to placebo and other analgesic techniques in adult patients. RESULTS: Forty-two randomized-controlled trials provided the data for this systematic review. Eight studies were assessed as high risk of bias in at least one domain. The included studies had significant heterogeneity with regard to the type of surgery, comparator groups, and outcomes measured; therefore, a limited quantitative analysis was undertaken for the comparison of QLB vs no block or placebo in patients undergoing Cesarean delivery only. For Cesarean delivery, the QLB reduced the opioid use by 24.1 (95% confidence interval, 17.3 to 30.9) mg oral morphine equivalents in the first postoperative 24 hr compared with no block or placebo with no difference in pain scores at rest. For other surgical procedures, the pain scores and opioid use were lower in the QLB group when compared with placebo or no regional anesthesia technique. When compared with other regional anesthetic techniques, the analgesic benefit of QLB was marginal. CONCLUSION: Quadratus lumborum block provided analgesic benefits compared with placebo for use in the abdominal wall and hip surgery, with only marginal benefits compared with other regional analgesic techniques. The identified studies used different variants of QLB in many different surgery types. These findings and conclusions, therefore, should be considered preliminary. TRIAL REGISTRATION: PROSPERO (CRD42018095965); registered 6 June 2018.

RéSUMé: OBJECTIF: L'objectif de cette revue systématique était de déterminer l'efficacité d'un bloc du muscle du carré des lombes pour l'analgésie postopératoire après une chirurgie impliquant la paroi abdominale ou les hanches, comparativement à un placebo ou à d'autres techniques analgésiques. MéTHODE: Nous avons réalisé des recherches dans les bases de données électroniques (Medline, Embase, Cochrane Central, et Scopus) pour trouver les mots-clés et les termes de vocabulaire contrôlé liés au bloc du carré des lombes depuis la création des bases de données jusqu'au mois de novembre 2019. Les études incluses comparaient une injection échoguidée unique pour réaliser un bloc du carré des lombes à un placebo et à d'autres techniques analgésiques chez des patients adultes. RéSULTATS: Quarante-deux études randomisées contrôlées ont fourni des données pour cette revue systématique. Huit études démontraient un risque élevé de biais dans au moins un domaine. Les études incluses présentaient une hétérogénéité importante en matière de type de chirurgie, de groupes comparés, et de résultats mesurés; une analyse quantitative limitée a par conséquent été entreprise pour comparer l'utilisation d'un bloc du muscle carré des lombes vs aucun bloc ou un placebo chez des patientes subissant un accouchement par césarienne. Lors d'un accouchement par césarienne, le bloc du carré des lombes a réduit la consommation d'opioïdes de 24,1 (intervalle de confiance 95 %, 17,3 à 30,9) mg en équivalent de morphine orale au cours des premières 24 h postopératoires par rapport à un accouchement par césarienne sans bloc ou avec placebo, et aucune différence n'a été observée dans les scores de douleur au repos. En ce qui a trait aux autres interventions chirurgicales, les scores de douleur et la consommation d'opioïdes étaient plus bas dans le groupe bloc du carré des lombes par rapport aux groupes placebo / aucune technique d'anesthésie régionale. Comparativement à d'autres techniques d'anesthésie régionale, les bienfaits analgésiques d'un bloc du carré des lombes étaient marginaux. CONCLUSION: Le bloc du carré des lombes a procuré des bienfaits analgésiques par rapport à un placebo lorsqu'il était utilisé en cas de chirurgie impliquant la paroi abdominale ou la hanche, mais ses bienfaits étaient marginaux comparativement aux autres techniques d'analgésie régionale. Les études identifiées utilisaient différentes variantes du bloc du carré des lombes dans de nombreux types différents de chirurgie. Il convient donc de considérer comme préliminaires ces observations et conclusions. ENREGISTREMENT DE L'éTUDE: PROSPERO (CRD42018095965); enregistrée le 6 juin 2018.

Top ten priorities for anesthesia and perioperative research: a report from the Canadian Anesthesia Research Priority Setting Partnership.

PURPOSE: The purpose of the Canadian Anesthesia Research Priority Setting Partnership (CAR PSP) was to identify a top ten list of shared priorities for research in anesthesia and perioperative care in Canada. METHODS: We used the methods of the James Lind Alliance to involve patients, caregivers, healthcare professionals, and researchers in determining the research priorities in Canada. In a first survey, participants submitted questions that they want research to answer about anesthesia and perioperative care. We summarized those responses into a longlist of questions. We reviewed the literature to see if any of those questions were already answered. In a second survey, participants chose up to ten questions from the longlist that they thought were most important to be answered with research. From that list, the highest ranking questions were discussed and assigned a final rank at an in-person workshop. RESULTS: A total of 254 participants submitted 574 research suggestions that were then summarized into 49 questions. Those questions were checked against the literature to be sure they were not already adequately addressed, and in a second survey of those 49 questions, participants chose up to 10 that they thought were most important. A total of 233 participants submitted their priorities, which were then used to choose 24 questions for discussion at the final workshop. At the final workshop, 22 participants agreed on a top ten list of priorities. CONCLUSION: The CAR PSP top ten priorities reflect a wide variety of priorities captured by a broad spectrum of Canadians who receive and provide anesthesia care. The priorities are a tool to initiate and guide patient-oriented research in anesthesia and perioperative care.

RéSUMé: OBJECTIF: L'objectif du Partenariat canadien pour l'établissement des priorités de la recherche en anesthésie (CAR-PSP) était d'établir une liste des dix principales priorités pour la recherche sur les soins anesthésiques et périopératoires au Canada. MéTHODES: Nous avons utilisé la méthodologie de la James Lind Alliance pour impliquer des patients, des aidants, des professionnels de la santé et des chercheurs afin de déterminer quelles étaient les priorités en matière de recherche au Canada. Dans une première enquête, les participants ont envoyé des questions sur les soins anesthésiques et périopératoires auxquelles ils voulaient que la recherche réponde. Nous avons résumé ces envois par une liste exhaustive de questions. Nous avons passé en revue les publications pour voir s'il existait déjà des réponses à ces questions. Dans une deuxième étude, les participants ont choisi dans la liste jusqu'à dix questions qui leur semblaient les plus importantes et pour lesquelles la recherche devrait fournir des réponses. À partir de cette liste, les questions les mieux classées ont été discutées et un classement définitif leur a été attribué au cours d'un atelier où tous les participants étaient présents en personne. RéSULTATS: Au total, 254 participants ont envoyé 574 suggestions de recherche qui ont été résumées en 49 questions. La littérature a été examinée pour s'assurer que ces questions n'avaient pas déjà reçu des réponses adéquates, et dans une seconde étude, les participants ont choisi jusqu'à 10 questions qu'ils jugeaient les plus importantes parmi ces 49 questions. Au total, 233 participants ont communiqué leurs priorités qui ont alors servi à choisir 24 questions ouvertes pour la discussion dans un atelier final. Dans cet atelier, 22 participants se sont mis d'accord sur une liste des dix principales priorités. CONCLUSION: Les dix principales priorités du CAR-PSP sont le reflet d'un grand éventail de priorités venant de Canadiens de tous horizons qui reçoivent ou fournissent des soins d'anesthésie. Ces priorités sont un outil permettant d'entamer et de guider une recherche axée sur le patient dans le domaine des soins anesthésiques et périopératoires.

A randomized trial of phenylephrine infusion versus bolus dosing for nausea and vomiting during Cesarean delivery in obese women.

PURPOSE: Hypotension is common after spinal anesthesia for Cesarean delivery. It is associated with nausea, vomiting, and fetal acidosis. Previous research on phenylephrine excluded obese subjects. We compared the incidence of intraoperative nausea and vomiting (IONV) in obese patients who received a prophylactic phenylephrine infusion vs those who received bolus dosing for the treatment of spinal-induced hypotension. METHODS: In this multicentre, double-blinded randomized controlled trial, 160 obese women undergoing elective Cesarean delivery under spinal anesthesia were randomized to receive a prophylactic phenylephrine infusion initiated at 50 µg·min-1 (and titrated according to a predefined algorithm) or 100 µg phenylephrine boluses to treat hypotension. Maternal systolic blood pressure was maintained within 20% of baseline. The primary study outcome was the incidence of IONV. RESULTS: Intraoperative nausea and vomiting were significantly reduced in the infusion group compared to the bolus group (46% vs 75%, respectively; relative risk [RR], 0.61; 95% confidence interval [CI], 0.47 to 0.80; P < 0.001). This was associated with significantly reduced need for intraoperative rescue antiemetics (26% vs 42%, respectively; RR, 0.62; 95% CI, 0.40 to 0.97; P = 0.04), but no difference in the incidence of vomiting. Postoperative vomiting at two hours was reduced in the infusion group (11% vs 25%; RR, 0.44; 95% CI, 0.21 to 0.90; P = 0.02);however, there were no differences in the incidence or severity of postoperative nausea, need for rescue antiemetics at two hours and 24 hr, or the incidence of postoperative vomiting at 24 hr. CONCLUSION: In obese women undergoing Cesarean delivery with spinal anesthesia, prophylactic phenylephrine infusion was associated with less intraoperative nausea, less need for rescue antiemetics, and reduced early postoperative vomiting. TRIAL REGISTRATION: www.clinicaltrials.gov (NCT01481740). Registered 22 July 2011.

Hyperbaric Versus Isobaric Bupivacaine for Spinal Anesthesia: Systematic Review and Meta-analysis for Adult Patients Undergoing Noncesarean Delivery Surgery.

BACKGROUND: It is widely believed that the choice between isobaric bupivacaine and hyperbaric bupivacaine formulations alters the block characteristics for the conduct of surgery under spinal anesthesia. The aim of this study was to systematically review the comparative evidence regarding the effectiveness and safety of the 2 formulations when used for spinal anesthesia for adult noncesarean delivery surgery. METHODS: Key electronic databases were searched for randomized controlled trials, excluding cesarean delivery surgeries under spinal anesthesia, without any language or date restrictions. The primary outcome measure for this review was the failure of spinal anesthesia. Two independent reviewers selected the studies and extracted the data. Results were expressed as relative risk (RR) or mean differences (MDs) with 95% confidence intervals (CIs). RESULTS: Seven hundred fifty-one studies were identified between 1946 and 2016. After screening, there were 16 randomized controlled clinical trials, including 724 participants, that provided data for the meta-analysis. The methodological reporting of most studies was poor, and appropriate judgment of their individual risk of bias elements was not possible. There was no difference between the 2 drugs regarding the need for conversion to general anesthesia (RR, 0.60; 95% CI, 0.08-4.41; P = .62; I = 0%), incidence of hypotension (RR, 1.15; 95% CI, 0.69-1.92; P = .58; I = 0%), nausea/vomiting (RR, 0.29; 95% CI, 0.06-1.32; P = .11; I = 7%), or onset of sensory block (MD = 1.7 minutes; 95% CI, -3.5 to 0.1; P = .07; I = 0%). The onset of motor block (MD = 4.6 minutes; 95% CI, 7.5-1.7; P = .002; I = 78%) was significantly faster with hyperbaric bupivacaine. Conversely, the duration of motor (MD = 45.2 minutes; 95% CI, 66.3-24.2; P < .001; I = 87%) and sensory (MD = 29.4 minutes; 95% CI, 15.5-43.3; P < .001; I = 73%) block was longer with isobaric bupivacaine. CONCLUSIONS: Both hyperbaric bupivacaine and isobaric bupivacaine provided effective anesthesia with no difference in the failure rate or adverse effects. The hyperbaric formulation allows for a relatively rapid motor block onset, with shorter duration of motor and sensory block. The isobaric formulation has a slower onset and provides a longer duration of both sensory and motor block. Nevertheless, the small sample size and high heterogeneity involving these outcomes suggest that all the results should be treated with caution.

Epidural Volume Extension During Combined Spinal-Epidural Labor Analgesia Does Not Increase Sensory Block.

BACKGROUND: Combined spinal-epidural (CSE) analgesia is widely used for delivering labor analgesia. Epidural volume extension (EVE) involves the injection of fluid into the epidural space compressing the dural sac, causing cephalad shift of the cerebral spinal fluid. Our hypothesis was that EVE with 10 mL normal saline during CSE would increase the sensory block height at 15 minutes after intrathecal injection. We expected EVE to decrease pain scores, decrease analgesia onset time, and decrease motor block compared with performing CSE without EVE (NEVE). METHODS: We randomly assigned 60 healthy term laboring nulliparous parturients with cervical dilation <5 cm to receive CSE either with EVE of 10 mL normal saline through the Tuohy needle before catheter insertion or CSE NEVE. Intrathecal analgesia consisted of 2 mg plain bupivacaine and 10 µg fentanyl (1 mL total). A blinded researcher assessed sensory dermatome level, analgesia, and motor blockade at regular intervals for 30 minutes. The primary outcome measure was the median peak sensory dermatome level at 15 minutes. RESULTS: Fifty-four parturients were analyzed. There was no significant difference in peak sensory dermatome levels at 15 minutes (median difference, 1 dermatome level; 95% confidence interval of median difference, 0 to 2; P = 0.22) and 30 minutes (median difference, 0 dermatome level; 95% confidence interval, -2 to 2; P = 0.76). There was no difference in the time to peak dermatome, minimum pain score, or the time to minimum pain score between groups. CONCLUSIONS: We found no significant difference between groups with regard to sensory dermatome level or pain scores when using EVE compared with NEVE. Our study demonstrates that addition of EVE does not offer superior analgesia when using a CSE technique for parturients requesting labor analgesia.

Hypertensive disorders of pregnancy.

PURPOSE: In this continuing professional development module, we review recent Society of Obstetricians and Gynaecologists of Canada (SOGC) guidelines for the classification and diagnosis of hypertensive disorders of pregnancy (HDP) as well as review the clinical features, laboratory investigations, and outcomes of HDP. We explore the evidence for anesthetic management and prevention of end-organ damage in women with HDP and describe the role and contribution of anesthesiologists as part of a multidisciplinary care team. PRINCIPAL FINDINGS: Hypertensive disorders of pregnancy can have variable presentations with clinical signs and symptoms that often do not correlate with the underlying severity and progression of the disease. Failure of timely diagnosis and treatment contributes significantly to adverse maternal (neurologic complications, pulmonary edema, and postpartum hemorrhage) and neonatal (respiratory and neurologic complications and stillbirth) outcomes. In the Canadian context, improvements in medical care have led to better maternal and neonatal outcomes. Timing of delivery is crucial in balancing maternal risks and fetal benefits of ongoing pregnancy. Evidence-based SOGC guidelines regarding diagnosis and management of HDP address many aspects of clinical care relevant to anesthesiologists, who have an important role in the multidisciplinary care team. CONCLUSIONS: Hypertensive disorders of pregnancy are on the rise worldwide, and this trend is expected to continue. The major contributors to maternal mortality are failure to recognize HDP promptly or to treat the condition adequately. It is essential that anesthesiologists understand the disease process and acquire knowledge of the guidelines governing current obstetrical care in order to provide evidence-based multidisciplinary quality care to these patients. Anesthetic management helps prevent potentially deleterious maternal and fetal outcomes.

A randomized placebo-controlled trial of two doses of pregabalin for postoperative analgesia in patients undergoing abdominal hysterectomy.

PURPOSE: Acute pain after open abdominal hysterectomy limits the function of patients in the postoperative period, but data regarding the analgesic efficacy of a low dose of pregabalin (75 or 150 mg) have been conflicting. This study was performed to determine if a low dose of pregabalin could decrease postoperative opioid use following abdominal hysterectomy when compared with placebo. METHODS: American Society of Anesthesiologists I-II patients older than 18 yr and scheduled for open elective abdominal hysterectomy were recruited for participation and randomized to one of three groups: pregabalin 75 mg (P75), pregabalin 150 mg (P150), or placebo. The study drug was administered two hours prior to surgery and 12 hr following the initial dose. Anesthetic technique and postoperative analgesia were standardized. Postoperative pain was managed using patient-controlled analgesia with morphine. Pain at rest and movement as well as nausea were assessed with an 11-point numeric rating scale. RESULTS: One hundred and one patients were recruited, and 89 patients completed the study. Mean (SD) cumulative morphine consumption at 24 hr postoperatively was 54.0 (26.2) mg for the placebo group, 53.1 (22.7) mg for the P75 group, and 44.3 (20.9) mg for the P150 group. Independent Student's t tests indicated no difference between the placebo group and either the P75 group (95% confidence interval [CI]: -11.75 to 13.44; P = 0.8937) or the P150 group (95% CI: -2.74 to 22.15; P = 0.1238). CONCLUSIONS: At the doses used in this study, pregabalin treatment may not be effective in reducing opioid use up to 24 hr postoperatively following abdominal hysterectomy. This trial was registered at www.ClinicalTrials.gov : NCT00781131.

Transversus abdominis plane block does not improve early or late pain outcomes after Cesarean delivery: a randomized controlled trial.

OBJECTIVES: Cesarean delivery is a common surgical procedure with anticipated substantial postoperative pain. The addition of a transversus abdominis plane block (TAPB) to a multimodal analgesic regimen that includes intrathecal morphine may provide improved early pain outcomes and decrease the risk of chronic post-surgical pain. The purpose of this research was to assess the ability of an ultrasound-guided TAPB with low-dose ropivacaine to decrease early postoperative pain, opioid consumption, and risk of developing persistent pain when compared with a placebo block. METHODS: Eighty-three women were randomly assigned to either a treatment (0.25% ropivacaine) or control group (0.9% saline) in this double-blind trial, and 74 women were included in the final analysis. Ultrasound-guided TAPBs were performed with an injection of 20 mL of study solution per side. The primary outcome measures of this study were: pain at rest and pain after movement measured with a numeric rating scale, results of the Quality of Recovery-40 (QoR-40) questionnaire, and opioid consumption at 24 hr. These were used with an a priori sample size calculation to detect a 30% reduction in pain scores, a 10% improvement in QoR-40 score, and a 50% reduction in opioid consumption. Health quality and physical functioning were assessed using the Short Form 36 (SF-36®) Health Survey at 30 days and six months. RESULTS: Assessment at 24 hr after Cesarean delivery revealed no clinically important differences between groups in postoperative pain, QoR-40, or opioid consumption. There were no clinically important differences between groups regarding measures of nausea, pruritus, vomiting, urine retention (2, 24, and 48 hr postoperatively), 24-hr QoR-40 sub-dimensions, or the SF-36 Health Survey (30 days and six months postoperatively). CONCLUSIONS: Ultrasound-guided TAPB did not improve postoperative pain, quality of recovery, or opioid consumption 24 hr following surgery. Similar health and functioning (SF-36) at 30 days and six months were reported by both groups. This trial was registered at ClinicalTrials.gov number: NCT01261637.

Difficult and failed intubation: Incident rates and maternal, obstetrical, and anesthetic predictors.

BACKGROUND: Difficult and failed tracheal intubation may be more common in the obstetrical population. The objective of this study was to determine the incidence of difficult and failed tracheal intubation in a Canadian tertiary care obstetric hospital and to identify predictors. METHODS: Maternal, perinatal, and anesthetic information on all pregnant women or recently pregnant (up to three days postpartum) women undergoing general anesthesia (GA) from 1984 to 2003 at the Izaac Walton Killam Health Centre (IWK) was abstracted from the Nova Scotia Atlee Perinatal Database, and the information was augmented by chart review. The incidence and predictors of difficult and failed tracheal intubation were determined. Analyses using logistic regression were performed for the complete GA cohort and for the subgroup that had Cesarean delivery under GA. RESULTS: There were 102,587 deliveries of ≥20 weeks gestation in the study population, with 3,107 GAs identified, 2,986 records reviewed, and 2,633 GAs (88%) retained in the complete cohort. Difficult tracheal intubation was encountered in 123 of 2,633 (4.7%) women in the complete cohort and 60 of 1,052 (5.7%) women in the Cesarean delivery subgroup. Only two failed tracheal intubations were identified (0.08%) in the complete cohort, and both occurred during GAs for postpartum tubal ligation. The combined rate of difficult/failed tracheal intubation remained stable over the 20 years reviewed despite decreasing GA rates. Amongst the complete cohort, maternal age ≥35 yr, weight at delivery 90 to 99 kg, and absence of labour predicted increased risks; while weight at delivery 90 to 99 kg and absence of labour amongst the Cesarean delivery subgroup predicted difficult/failed tracheal intubation. CONCLUSION: Previously accepted risk factors, such as labour, pre-existing medical conditions and obstetrical disorders, did not predict an increased risk of difficult tracheal intubation, while maternal age ≥35 yr, weight 90 to 99 kg, and absence of active labour were found to predict increased risk.

Supplemental oxygen does not prevent postoperative nausea and vomiting after gynecological laparoscopy.

PURPOSE: Postoperative nausea and vomiting are among the most common and distressing side effects of general anesthesia. Supplemental intraoperative 80% oxygen reduces postoperative nausea and vomiting following open and laparoscopic abdominal surgery. However, this benefit has not been observed in other patient populations. We undertook this study to evaluate the effect of 80% supplemental intraoperative oxygen on the incidence of postoperative nausea and vomiting following ambulatory surgery for laparoscopic tubal ligation. METHODS: Following Research Ethics Board approval, 304 subjects were enrolled into one of two arms of a randomized prospective controlled study. The intervention group (n = 147) breathed 80% oxygen and the control group (n = 145) breathed routine 30% oxygen (balance medical air) while both groups were receiving a standardized general anesthetic. Nausea was assessed as: none, mild, moderate, or severe; vomiting was any emetic episode or retching. Any assessment either greater than none (nausea) or greater than zero (vomiting) was considered positive. RESULTS: The incidence of postoperative nausea and vomiting up to 24 hr following surgery was 69% in the 80% oxygen intervention group and 65% in the 30% oxygen control group (P = 0.62). There were no differences in nausea alone, vomiting, or antiemetic use in the postoperative anesthetic care unit or at any time (pre- or post-discharge) up to 24 hr after surgery. CONCLUSIONS: This trial of 304 women did not demonstrate that administering intraoperative supplemental 80% oxygen during ambulatory surgery for laparoscopic tubal ligation prevented postoperative nausea or vomiting during the initial postoperative 24 hr compared with women who received routine 30% oxygen.