Prevention of hypotension after spinal anaesthesia for caesarean section: a systematic review and network meta-analysis of randomised controlled trials.

Spinal anaesthesia for caesarean section commonly causes maternal hypotension. This systematic review and network meta-analysis compared methods to prevent hypotension in women receiving spinal anaesthesia for caesarean section. We selected randomised controlled trials that compared an intervention to prevent hypotension with another intervention or inactive control by searching MEDLINE and Embase, Web of Science to December 2018. There was no language restriction. Two reviewers extracted data on trial characteristics, methods and outcomes. We assessed risk of bias for individual trials (Cochrane tool) and quality of evidence (GRADE checklist). We assessed 109 trials (8561 women) and 12 different methods that resulted in 30 direct comparisons. Methods ranked by OR (95%CI) from most effective to least effective were: metaraminol 0.11 (0.04-0.26); norepinephrine 0.13 (0.06-0.28); phenylephrine 0.18 (0.11-0.29); leg compression 0.25 (0.14-0.43); ephedrine 0.28 (0.18-0.43); colloid given before induction of anaesthesia 0.38 (0.24-0.61); angiotensin 2, 0.12 (0.02-0.75); colloid given after induction of anaesthesia 0.52 (0.30-0.90); mephentermine 0.09 (0.01-1.30); crystalloid given after induction of anaesthesia 0.78 (0.46-1.31); and crystalloid given before induction of anaesthesia 1.16 (0.76-1.79). Phenylephrine caused maternal bradycardia compared with control, OR (95%CI) 0.23 (0.07-0.79). Ephedrine lowered umbilical artery pH more than phenylephrine, standardised mean difference (95%CI) 0.78 (0.47-1.49). We conclude that vasopressors should be given to healthy women to prevent hypotension during caesarean section with spinal anaesthesia.

Choice of anaesthesia for category-1 caesarean section in women with anticipated difficult tracheal intubation: the use of decision analysis.

A predicted difficult airway is sometimes considered a contra-indication to rapid sequence induction of general anaesthesia, even in an urgent case such as a category-1 caesarean section for fetal distress. However, formally assessing the risk is difficult because of the rarity and urgency of such cases. We have used decision analysis to quantify the time taken to establish anaesthesia, and probability of failure, of three possible anaesthetic methods, based on a systematic review of the literature. We considered rapid sequence induction of general anaesthesia with videolaryngoscopy, awake fibreoptic intubation and rapid spinal anaesthesia. Our results show a shorter mean (95% CI) time to induction of 100 (87-114) s using rapid sequence induction compared with 9 (7-11) min for awake fibreoptic intubation (p < 0.0001) and 6.3 (5.4-7.2) min for spinal anaesthesia (p < 0.0001). We calculate the risk of ultimate failed airway control after rapid sequence induction to be 21 (0-53) per 100,000 cases, and postulate that some mothers may accept such a risk in order to reduce potential fetal harm from an extended time interval until delivery. Although rapid sequence induction may not be the anaesthetic technique of choice for all cases in the circumstance of a category-1 caesarean section for fetal distress with a predicted difficult airway, we suggest that it is an acceptable option.

Duration of analgesic effectiveness after the posterior and lateral transversus abdominis plane block techniques for transverse lower abdominal incisions: a meta-analysis.

BACKGROUND: Both posterior and lateral transversus abdominis plane (TAP) block techniques provide effective early (0-12 h) postoperative analgesia after transverse incision surgery. However, whether either technique produces prolonged analgesia lasting beyond 12 h remains controversial. This meta-analysis examines the duration of analgesia associated with posterior and lateral TAP blocks in the first 48 h after lower abdominal transverse incision surgery. METHODS: We retrieved randomized controlled trials (RCTs) investigating the analgesic effects of TAP block compared with control in patients undergoing lower abdominal transverse incision surgery. Outcomes sought included interval postoperative i.v. morphine consumption and also rest and dynamic pain scores at 12, 24, 36, and 48 h postoperatively. Opioid-related side-effects and patient satisfaction at 24 and 48 h were also assessed. The 12-24 h interval morphine consumption was designated as a primary outcome. RESULTS: Twelve RCTs including 641 patients were analysed. Four trials examined the posterior technique and eight assessed the lateral technique. Compared with control, the posterior TAP block reduced postoperative morphine consumption during the 12-24 h and 24-48 h intervals by 9.1 mg (95% CI: -16.83, -1.45; P=0.02) and 5 mg (95% CI: -9.54, -0.52; P=0.03), respectively. It also reduced rest pain scores at 24, 36, and 48 h, and also dynamic pain scores at 12, 24, 36, and 48 h. Differences were not significant with the lateral TAP block. CONCLUSION: Based on the comparisons with control, the posterior TAP block appears to produce more prolonged analgesia than the lateral TAP block. Future RCTs comparing these two techniques are required to confirm our findings.

Chronic kidney disease in pregnancy.

Parturients with renal insufficiency or failure present a significant challenge for the anesthesiologist. Impaired renal function compromises fertility and increases both maternal and fetal morbidity and mortality. Close communication amongst medical specialists, including nephrologists, obstetricians, neonatologists and anesthesiologists is required to ensure the safety of mother and child. Pre-existing diseases should be optimized and close surveillance of maternal and fetal condition is required. Kidney function may deteriorate during pregnancy, necessitating early intervention. The goal is to maintain hemodynamic and physiologic stability while the demands of the pregnancy change. Drugs that may adversely affect the fetus, are nephrotoxic or are dependent on renal elimination should be avoided.

Effect of intrathecal magnesium in the presence or absence of local anaesthetic with and without lipophilic opioids: a systematic review and meta-analysis.

Spinal anaesthesia is the primary anaesthetic technique for many types of surgery. Adjuncts to the local anaesthetics (LA) used in spinal anaesthesia can exhibit undesirable side-effects, limiting their use, but magnesium may have advantages in this respect. We sought randomized control trials (RCTs) in patients undergoing all types of surgery and in women in labour to compare the effect of intrathecal magnesium sulphate ± LA ± lipophilic opioid (experimental group) with the use of either intrathecal lipophilic opioids ± LA or LA only (control group). The primary outcome was the duration of spinal anaesthesia. Secondary outcomes were: onset and time to maximal sensory blockade, onset of motor block, and duration of sensory and motor blockade. We found 15 RCTs comprising 980 patients. The duration of spinal anaesthesia was significantly increased in the experimental group [standardized mean difference (SMD) -1.05 (-1.70, -0.41) (P = 0.001)], compared with the control group. This increased duration of spinal anaesthesia was seen in non-obstetric studies, SMD -1.38 (-2.11, -0.66) (P = 0.0002), but not in obstetric studies, SMD -0.55 (-1.87, 0.77) (P = 0.41). There was no delay in the onset of sensory or motor blockade. The incidence of hypotension and pruritus was similar in both groups. Heterogeneity was high in all outcome measures. The duration of spinal anaesthesia may be increased by the addition of magnesium to lipophilic opioids ± LA.

Transversus abdominis plane block for postoperative analgesia after Caesarean delivery performed under spinal anaesthesia? A systematic review and meta-analysis.

The transversus abdominis plane (TAP) block is a field block that provides postoperative analgesia for abdominal surgery. Its analgesic utility after Caesarean delivery (CD) remains controversial. This systematic review and meta-analysis examines whether TAP block can reduce i.v. morphine consumption in the first 24 h after CD. The authors retrieved randomized controlled trials comparing TAP block with placebo in CD. Postoperative i.v. morphine consumption during the first 24 h was selected as a primary outcome. Pain scores and both maternal and neonatal opioid-related side-effects were secondary outcomes. Where possible, meta-analytic techniques and random effects modelling were used to combine data. Trials were stratified based on whether or not spinal morphine was used as part of the analgesic regimen. Five trials including 312 patients were identified. TAP block reduced the mean 24 h i.v. morphine consumption by 24 mg [95% confidence interval (CI) -39.65 to -7.78] when spinal morphine was not used. TAP block also reduced visual analogue scale pain scores (10 cm line where 0 cm, no pain, and 10 cm, worst pain) by 0.8 cm (95% CI -1.53 to -0.05, P=0.01), and decreased the incidence of opioid-related side-effects. The differences in primary and secondary outcomes were not significant when spinal morphine was used. TAP block provides superior analgesia compared with placebo and can reduce the first 24 h morphine consumption in the setting of a multimodal analgesic regimen that excludes spinal morphine. TAP block can provide effective analgesia when spinal morphine is contraindicated or not used.

Peripartum anesthetic management of patients with aortic valve stenosis: a retrospective study and literature review.

BACKGROUND: Anesthetic management of parturients with aortic stenosis is controversial. Early studies suggest maternal mortality was related to cardiac condition and anesthetic care. In this report, management of parturients with moderate or severe aortic stenosis in two institutions is compared, and published cases are reviewed. METHODS: Peripartum anesthetic management of all parturients with moderate or severe aortic stenosis who gave birth between 1990 and 2005 at our institutions, is described. Patients with mild or non-valvular aortic stenosis were excluded. RESULTS: There were 12 parturients, six with moderate and six with severe aortic stenosis. Two patients with moderate aortic stenosis were New York Heart Association (NYHA) classification II, the others were asymptomatic. Five patients with severe aortic stenosis were symptomatic (NYHA classification II or III). Two patients with moderate and three with severe aortic stenosis underwent cesarean delivery; epidural anesthesia was used for two. Two patients with moderate and all with serious aortic stenosis were observed postpartum for 24 to 48 h in a high-dependency unit. There were no severe maternal or neonatal complications. CONCLUSIONS: Carefully titrated regional analgesia is usually well tolerated in patients undergoing vaginal or cesarean delivery even in the presence of severe aortic stenosis. Standard monitoring is usually adequate for vaginal delivery, but invasive monitoring may facilitate management in some patients. An arterial line allows close monitoring of systemic blood pressure. Facilities for close 24-48-h post-partum observation should be available. A multidisciplinary approach is needed.

Conversion of epidural labour analgesia to anaesthesia for Caesarean section: a prospective study of the incidence and determinants of failure.

BACKGROUND: The incidence of general anaesthesia (GA) has been used as a marker for the quality of obstetric anaesthesia care. Recent guidelines suggest the rate of GA for Caesarean section in parturients with pre-existing epidural analgesia for labour should be <3%. The primary purpose of this study is to determine whether or not this is an achievable standard in a university teaching hospital. We also wished to determine the factors influencing the incidence of inadequate anaesthesia. METHODS: We studied a consecutive cohort of 501 patients who had a Caesarean section after epidural labour analgesia. The incidence of GA, the total incidence of failure, and the factors previously associated with failure were recorded. Factors shown to be significant with univariate analysis were used in a binary logistic regression to determine the independent risk factors for failure. RESULTS: Twenty-one of 501 parturients required GA (4.1%, 95% confidence interval 2.6-6.3%), not significantly different from 3% (P=0.1). Fifteen of 21 (71%) of these occurred intraoperatively. The total rate of failure was 30/501 (5.9%, 95% confidence interval 4.0-8.4%). Maternal height and the number of clinician top-ups in labour were the significant independent risk factors for failure. CONCLUSIONS: Intraoperative conversion to GA may increase both maternal and fetal risks. Strategies to reduce the incidence may include early recognition of inadequate labour analgesia and reliable assessment of adequacy of surgical anaesthesia.

Compliance with the CONSORT checklist in obstetric anaesthesia randomised controlled trials.

The Consolidated Standards for Reporting of Trials (CONSORT) checklist is an evidence-based approach to help improve the quality of reporting randomised controlled trials. The purpose of this study was to determine how closely randomised controlled trials in obstetric anaesthesia adhere to the CONSORT checklist. We retrieved all randomised controlled trials pertaining to the practice of obstetric anaesthesia and summarised in Obstetric Anesthesia Digest between March 2001 and December 2002 and compared the quality of reporting to the CONSORT checklist. The median number of correctly described CONSORT items was 65% (range 36% to 100%). Information pertaining to randomisation, blinding of the assessors, sample size calculation, reliability of measurements and reporting of the analysis were often omitted. It is difficult to determine the value and quality of many obstetric anaesthesia clinical trials because journal editors do not insist that this important information is made available to readers. Both clinicians and clinical researchers would benefit from uniform reporting of randomised trials in a manner that allows rapid data retrieval and easy assessment for relevance and quality.

The neurologic and adaptive capacity score is not a reliable method of newborn evaluation.

BACKGROUND: The Neurologic and Adaptive Capacity Score (NACS) is a multi-item scale that was published in 1982 to measure the effects of intrapartum drugs on the neonate. Although this scoring system has been widely used in obstetric anesthesia research, studies confirming its reliability have not been published. The purpose of this study was to assess the reliability of the NACS. METHODS: Two teams of observers were trained to perform the NACS on healthy, term neonates born in the vertex presentation. Two examinations were performed on each neonate within the first 2.5 h of life. Simultaneous (or "split-half") reliability was assessed using the alpha coefficient. Test-retest reliability was assessed using the intraclass correlation coefficient. The test was considered to be reliable if a was greater than 0.7 and the intraclass correlation coefficient was greater than 0.6. RESULTS: Two hundred babies were studied. The a was 0.47 and the intraclass correlation coefficient was 0.38 (95% confidence interval, 0.24-0.52). CONCLUSIONS: The NACS had poor reliability both on simultaneous testing and in the test-retest situation when used to evaluate term, healthy neonates. The authors suggest that other measures need to be developed to evaluate the effect of intrapartum drug administration in the neonate. Health measurement scales should undergo rigorous assessment for reliability and validity before they are used in clinical practice or for research purposes.

The effects of an increase of central blood volume before spinal anesthesia for cesarean delivery: a qualitative systematic review.

UNLABELLED: We evaluated in this qualitative systematic review the efficacy of increasing central blood volume on the incidence of hypotension after spinal anesthesia for elective cesarean delivery. Randomized controlled trials investigating any method of increasing central blood volume before the initiation of obstetric spinal anesthesia were sought by using MEDLINE (1966-2000), Embase (January 1988-April 2000), and the Cochrane Library (Issue 1, 2000). Additional reports from retrieved and review articles, hand searching of non-MEDLINE journals, and abstracts of major anesthesia meetings (1994-1999) were located. The primary outcome was the incidence of hypotension. Secondary outcomes included: ephedrine use, Apgar scores, umbilical cord pH values, and maternal nausea and vomiting. Twenty-three articles met our inclusion criteria with the use of crystalloid preload, colloid preload, and mechanical methods of increasing central volume. Crystalloid preload was inconsistent in preventing hypotension, whereas colloid appeared to be effective in all but one study. Leg wrapping and thromboembolic stockings decreased the incidence of hypotension compared with leg elevation or control. Few differences in fetal outcomes or maternal nausea and vomiting were reported. Increasing central blood volume by using colloid and leg wrapping decreases but does not abolish the incidence of hypotension before spinal anesthesia for elective cesarean delivery. IMPLICATIONS: We performed a systematic review to determine whether fluid loading reduced the incidence of low blood pressure after spinal anesthesia for cesarean delivery. Although no technique totally eliminates the occurrence of hypotension, colloid administration (starch or gelatin containing fluids) and leg wrapping were the most effective.

Examining the evidence in anesthesia literature: a critical appraisal of systematic reviews.

UNLABELLED: Systematic reviews are structured reviews that use scientific strategies to reduce bias in the collection, appraisal, and interpretation of relevant studies. We undertook a systematic review of published systematic reviews in perioperative medicine to summarize the areas currently covered by this type of literature, to evaluate the quality of systematic reviews in this field, and to assess some of the methodologic and reporting issues that are unique to systematic reviews. Computerized bibliographic databases, citation review, and hand searches were performed to identify eligible articles. Quality was assessed using the Overview Quality Assessment Questionnaire. Eight-two systematic reviews were found. Reviews in perioperative medicine tended to evaluate prophylactic or therapeutic interventions. No differences were seen in quality between reviews published in anesthesia and nonanesthesia journals. Nearly half of all systematic reviews had only minor or minimal flaws; however, methods can be improved with expanded search strategies, use of least two reviewers to assess each study, use of validated methods to evaluate quality, and assessment of potential sources of bias. IMPLICATIONS: The quality of systematic reviews relating to perioperative medicine was examined systematically and found to be similar in quality to those in other specialties. Adoption of recently published criteria on writing and methods could further improve this type of literature.