High-Flow Nasal Cannula for Apneic Oxygenation in Obese Patients for Elective Surgery: A Systematic Review and Meta-Analysis.

BACKGROUND: Obese patients desaturate rapidly during the apneic period after induction of anesthesia for elective surgery. Administration of oxygen using high-flow nasal cannulae (HFNCs) may prevent desaturation in nonobese patients compared to facemask (FM) preoxygenation. The aim of this meta-analysis was to compare the effectiveness of HFNC to FM preoxygenation techniques in reducing preintubation desaturation in obese patients undergoing elective surgery. METHODS: This study protocol was registered on PROSPERO (CRD42022309391). Adult studies that compared HFNC and FM preoxygenation in obese patients requiring general anesthesia for elective surgery were included. The primary outcome was desaturation resulting in oxygen saturation of <92% from induction of anesthesia until intubation. Secondary outcomes included the lowest arterial oxygen content before intubation expressed in mm Hg, safe apnea time expressed in seconds, the lowest oxygen saturation before intubation expressed as a percentage, patient-reported discomfort, the need for rescue ventilation, and the incidence of aspiration of gastric contents during intubation. Risk of bias was assessed using the Cochrane Collaboration tool. Certainty was assessed following the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach. RESULTS: Six studies including 351 participants were eligible for analysis. There was no difference in odds of oxygen desaturation <92% between HFNC and FM (odds ratio [OR], 0.49; 95% confidence interval [CI], 0.15-1.63; P = .24). The HFNC group had a significantly longer safe apnea time (mean difference [MD], -124.20 with 95% CI, -200.47 to -47.93; P = .001). There was no difference between HFNC and FM in the lowest arterial oxygen content (MD, -23.90; 95% CI, -88.64 to 40.85; P = .47) and the lowest peripheral oxygenation saturation (MD, -0.47 with 95% CI, -5.07 to 4.12; P = .84). HFNC had a lower odd of discomfort than FM (OR, 0.13; 95% CI, 0.03-0.52; P = .004). There was no difference in the odds of aspiration of gastric contents between HFNC and FM (OR, 0.33; 95% CI, 0.01-8.21; P = .50). The risk of bias for our primary and secondary outcomes was low. The GRADE assessment for our primary outcome indicated a low level of certainty. For secondary outcomes, the GRADE assessment indicated a very low certainty for all outcomes except for patient discomfort, which was indicated as a moderate level of certainty. CONCLUSIONS: There may be no difference between HFNC and FM preoxygenation in preventing oxygen desaturation <92% or the lowest oxygen saturation before intubation. Preparation remains important to prevent and manage desaturation during induction of obese patients.

Combined spinal-epidural versus spinal anaesthesia for caesarean section.

BACKGROUND: Single-shot spinal anaesthesia (SSS) and combined spinal-epidural (CSE) anaesthesia are both commonly used for caesarean section anaesthesia. Spinals offer technical simplicity and rapid onset of nerve blockade which can be associated with hypotension. CSE anaesthesia allows for more gradual onset and also prolongation of the anaesthesia through use of a catheter. OBJECTIVES: To compare the effectiveness and adverse effects of CSE anaesthesia to single-shot spinal anaesthesia for caesarean section. SEARCH METHODS: We searched the Cochrane Pregnancy and Childbirth's Trials Register, ClinicalTrials.gov, the WHO International Clinical Trials Registry Platform (ICTRP), and reference lists of retrieved studies (search date: 8 August 2019). SELECTION CRITERIA: We considered all published randomised controlled trials (RCTs) involving a comparison of CSE anaesthesia with single-shot spinal anaesthesia for caesarean section. We further subgrouped spinal anaesthesia as either high-dose (10 or more mg bupivacaine), or low-dose (less than 10 mg bupivacaine). DATA COLLECTION AND ANALYSIS: Two review authors independently assessed trials for inclusion and risks of bias, extracted data and checked them for accuracy. We used standard methodological procedures expected by Cochrane. MAIN RESULTS: We identified 18 trials including 1272 women, but almost all comparisons for individual outcomes involved relatively small numbers of women. Two trials did not report on this review's outcomes and therefore contribute no data towards this review. Trials were conducted in national or university hospitals in Australia (1), Croatia (1), India (1), Italy (1), Singapore (3), South Korea (4), Spain (1), Sweden (1), Turkey (2), UK (1), USA (2). The trials were at a moderate risk of bias overall.CSE versus high-dose spinal anaesthesiaThere may be little or no difference between the CSE and high-dose spinal groups for the number of women requiring a repeat regional block or general anaesthetic as a result of failure to establish adequate initial blockade (risk ratio (RR) 0.32, 95% confidence interval (CI) 0.05 to 1.97; 7 studies, 341 women; low-quality evidence). We are uncertain whether having CSE or spinal makes any difference in the number of women requiring supplemental intra-operative analgesia at any time after CSE or spinal anaesthetic insertion (average RR 1.25, 95% CI 0.19 to 8.43; 7 studies, 390 women; very low-quality evidence), or the number of women requiring intra-operative conversion to general anaesthesia (RR 1.00, 95% CI 0.07 to 14.95; 7 studies, 388 women; very low-quality evidence). We are also uncertain about the results for the number of women who were satisfied with anaesthesia, regardless of whether they received CSE or high-dose spinal (RR 0.93 95% CI 0.73 to 1.19; 2 studies, 72 women; very low-quality evidence). More women in the CSE group (13/21) experienced intra-operative nausea or vomiting requiring treatment than in the high-dose spinal group (6/21). There were 11 cases of post-dural puncture headache (5/56 with CSE versus 6/57 with SSS; 3 trials, 113 women) with no clear difference between groups. There was also no clear difference in intra-operative hypotension requiring treatment (46/86 with CSE versus 41/76 with SSS; 4 trials, 162 women). There were no babies with Apgar score less than seven at five minutes (4 trials, 182 babies).CSE versus low-dose spinal anaesthesiaThere may be little or no difference between the CSE and low-dose spinal groups for the number of women requiring a repeat regional block or general anaesthetic as a result of failure to establish adequate initial blockade (RR 4.81, 95% CI 0.24 to 97.90; 3 studies, 224 women; low-quality evidence). Similarly, there is probably little difference in the number of women requiring supplemental intra-operative analgesia at any time after CSE or low-dose spinal anaesthetic insertion (RR 1.75, 95% CI 0.78 to 3.92; 4 studies, 298 women; moderate-quality evidence). We are uncertain about the effect of CSE or low-dose spinal on the need for intra-operative conversion to general anaesthesia, because this was not required by any of the 222 women in the three trials (low-quality evidence). None of the studies examined whether women were satisfied with their anaesthesia.The mean time to effective anaesthesia was faster in women who received low-dose spinal compared to CSE, although it is unlikely that the magnitude of this difference is clinically meaningful (standardised mean difference (SMD) 0.85 minutes, 95% CI 0.52 to 1.18 minutes; 2 studies, 160 women).CSE appeared to reduce the incidence of intra-operative hypotension requiring treatment compared with low-dose spinal (average RR 0.59, 95% CI 0.38 to 0.93; 4 studies, 336 women). Similar numbers of women between the CSE and low-dose spinal groups experienced intra-operative nausea or vomiting requiring treatment (3/50 with CSE versus 6/50 with SSS; 1 study, 100 women), and there were no cases of post-dural puncture headache (1 study, 138 women). No infants in either group had an Apgar score of less than seven at five minutes (1 study; 60 babies). AUTHORS' CONCLUSIONS: In this review, the number of studies and participants for most of our analyses were small and some of the included trials had design limitations. There was some suggestion that, compared to spinal anaesthesia, CSE could be associated with a reduction in the number of women with intra-operative hypotension, but an increase in intra-operative nausea and vomiting requiring treatment. One small study found that low-dose spinal resulted in a faster time to effective anaesthesia compared to CSE. However, these results are based on limited data and the difference is unlikely to be clinically meaningful. Consequently, there is currently insufficient evidence in support of one technique over the other and more evidence is needed in order to further evaluate the relative effectiveness and safety of CSE and spinal anaesthesia for caesarean section.More high-quality, sufficiently-powered studies in this area are needed. Such studies could consider using the outcomes listed in this review and should also consider reporting economic aspects of the different methods under investigation.

Perioperative corneal abrasions: A report of 42 cases from the webAIRS database.

Corneal abrasions are an uncommon complication of anaesthesia. The aim of this study was to identify potential risk factors, treatment and outcomes associated with corneal abrasions reported to the web-based anaesthesia incident reporting system (webAIRS), a voluntary de-identified anaesthesia incident reporting system in Australia and New Zealand, from 2009 to 2021. There were 43 such cases of corneal abrasions reported to webAIRS over this period. The most common postoperative finding was a painful eye. Common features included older patients, individuals with pre-existing eye conditions, general anaesthesia and procedures longer than 60 minutes. Most cases were treated with a combination of lubricating eye drops or aqueous antibiotic eye drops. The findings indicate that patients who sustain a perioperative corneal abrasion can be reassured that in many cases it will heal within 48 hours, but they should seek earlier review if symptoms persist or deteriorate. None of the cases in this series resulted in permanent harm. Well established eye protective measures are important to utilise throughout the perioperative period, including the time until the patient has recovered in the post-anaesthesia care unit.

Adult perioperative cardiac arrest: An overview of 684 cases reported to webAIRS.

There were 684 perioperative cardiac arrests reported to webAIRS between September 2009 and March 2022. The majority involved patients older than 60 years, classified as American Society of Anesthesiologists Physical Status 3 to 5, undergoing an emergency or major procedure. The most common precipitants included airway events, cardiovascular events, massive blood loss. medication issues, and sepsis. The highest mortality rate was 54% of the 46 cases in the miscellaneous category (this included 34 cases of severe sepsis, which had a mortality of 65%). This was followed by cardiovascular precipitants (n = 424) in which there were 147 deaths (35% mortality): these precipitants included blood loss (53%), embolism (61%) and myocardial infarction (70%). Airway and breathing events accounted for 25% and anaphylaxis 8%. A specialist anaesthetist attended the majority of these cardiac arrests. As webAIRS is a voluntary database, it is not possible to determine the incidence of perioperative cardiac arrest and only descriptive information on factors associated with cardiac arrest can be obtained. Nevertheless, the large number of reports includes a wide range of cases, precipitants, demographics and outcomes, providing ample opportunity to learn from these events. The data also provide rich scope for further research into further initiatives to prevent cardiac arrest in the perioperative period, and to improve outcomes, should a cardiac arrest occur.

The role of antibodies in Bacille Calmette Guérin-mediated immune responses and protection against tuberculosis in humans: A systematic review.

BACKGROUND: The mechanisms underlying Bacille Calmette-Guérin (BCG) vaccine's protective effects against tuberculosis (TB) are incompletely understood but are proposed to involve a predominantly cell-mediated process. However, there is increasing evidence for the involvement of antibodies in the control of Mycobacteria tuberculosis and in the immune response to BCG. METHODS: We did a systematic review of studies investigating anti-BCG antibodies in individuals with active or latent TB, and in the response to BCG vaccination. RESULTS: Of 1417 articles screened, 70 were relevant, comprising 52 investigating anti-BCG antibodies in TB and 18 investigating the anti-BCG antibody response to BCG-vaccination. Individuals with active TB have higher levels of anti-BCG antibodies compared with individuals with latent TB or healthy individuals. Antibodies to BCG are present after BCG vaccination. There is some evidence for the in utero transfer of maternal anti-BCG antibodies to infants. CONCLUSIONS: BCG vaccination induces a humoral response. Antibodies targeted against BCG and its antigens may play a role in protection against active TB.

Iatrogenic uvular injury related to airway instrumentation: A report of 13 cases from the webAIRS database and a review of uvular necrosis following inadvertent uvular injury.

Published reports of uvular necrosis are uncommon and it is possibly an under-reported complication of oropharyngeal manipulation. Uvular necrosis is thought to develop due to ischaemia secondary to mechanical compression of the uvula from oropharyngeal devices. Patients typically present with symptoms of a sore throat within 48 hours postoperatively. It is unclear whether there are any preventable factors, or any specific management strategies that might reduce this complication. Treatment is most commonly conservative management, including observation and simple analgesia. We present 13 cases of uvular injury that were reported to a web-based anaesthesia incident reporting system (webAIRS), a voluntary de-identified anaesthesia incident reporting system in Australia and New Zealand. While the postoperative findings varied, sore throat was the most frequent symptom. Most of the cases resolved spontaneously; the remainder with supportive treatment only. The findings suggest that patients who sustain a uvular injury can be reassured, but they should be advised to seek review early if sore throat persists or any difficulty with breathing develops.