Unsettled weather and the end for thiopental? Obstetric general anaesthesia after the NAP5 and MBRRACE-UK reports

Neonatal and early childhood outcomes following maternal anesthesia for cesarean section: a population-based cohort study

BACKGROUND

The fetus is vulnerable to maternal drug exposure. We determined associations of exposure to spinal, epidural, or general anesthesia on neonatal and childhood development outcomes during the first 1000 days of life.

METHODS

Population-based study of all singleton, cesarean livebirths of 24+0 to 43+6 weeks gestation between January 2007 and December 2016 in Scotland, stratified by urgency with follow-up to age 2 years. Models were adjusted for: maternal age, weight, ethnicity, socioeconomic status, smoking, drug-use, induction, parity, previous cesarean or abortion, pre-eclampsia, gestation, birth weight, and sex.

RESULTS

140 866 mothers underwent cesarean section (41.2% (57,971/140,866) elective, 58.8% (82,895/140,866) emergency) with general anesthesia used in 3.2% (1877/57,971) elective and 9.8% (8158/82,895) of emergency cases. In elective cases, general anesthesia versus spinal was associated with: neonatal resuscitation (crude event rate 16.2% vs 1.9% (adjusted RR 8.20, 95% CI 7.20 to 9.33), Apgar <7 at 5 min (4.6% vs 0.4% (adjRR 11.44, 95% CI 8.88 to 14.75)), and neonatal admission (8.6% vs 4.9% (adjRR 1.65, 95% CI 1.40 to 1.94)). Associations were similar in emergencies; resuscitation (32.2% vs 12.3% (adjRR 2.40, 95% CI 2.30 to 2.50)), Apgar <7 (12.6% vs 2.8% (adjRR 3.87, 95% CI 3.56 to 4.20), and admission (31.6% vs 19.9% (adjRR 1.20, 95% CI 1.15 to 1.25). There was a weak association between general anesthesia in emergency cases and having ≥1 concern noted in developmental assessment at 2 years (21.0% vs 16.5% (adjRR 1.08, 95% CI 1.01 to 1.16)).

CONCLUSIONS

General anesthesia for cesarean section, irrespective of urgency, is associated with neonatal resuscitation, low Apgar, and neonatal unit admission. Associations were strongest in non-urgent cases and at term. Further evaluation of long-term outcomes is warranted.

General anaesthetic and airway management practice for obstetric surgery in England: a prospective, multicentre observational study

There are no current descriptions of general anaesthesia characteristics for obstetric surgery, despite recent changes to patient baseline characteristics and airway management guidelines. This analysis of data from the direct reporting of awareness in maternity patients' (DREAMY) study of accidental awareness during obstetric anaesthesia aimed to describe practice for obstetric general anaesthesia in England and compare with earlier surveys and best-practice recommendations. Consenting patients who received general anaesthesia for obstetric surgery in 72 hospitals from May 2017 to August 2018 were included. Baseline characteristics, airway management, anaesthetic techniques and major complications were collected. Descriptive analysis, binary logistic regression modelling and comparisons with earlier data were conducted. Data were collected from 3117 procedures, including 2554 (81.9%) caesarean deliveries. Thiopental was the induction drug in 1649 (52.9%) patients, compared with propofol in 1419 (45.5%). Suxamethonium was the neuromuscular blocking drug for tracheal intubation in 2631 (86.1%), compared with rocuronium in 367 (11.8%). Difficult tracheal intubation was reported in 1 in 19 (95%CI 1 in 16-22) and failed intubation in 1 in 312 (95%CI 1 in 169-667). Obese patients were over-represented compared with national baselines and associated with difficult, but not failed intubation. There was more evidence of change in practice for induction drugs (increased use of propofol) than neuromuscular blocking drugs (suxamethonium remains the most popular). There was evidence of improvement in practice, with increased monitoring and reversal of neuromuscular blockade (although this remains suboptimal). Despite a high risk of difficult intubation in this population, videolaryngoscopy was rarely used (1.9%).

Incidence and risk factors for maternal hypoxaemia during induction of general anaesthesia for non-elective Caesarean section: a prospective multicentre study

BACKGROUND

Pregnant women are at increased risk of hypoxaemia during general anaesthesia. Our aim was to determine the incidence and the risk factors that contribute to hypoxaemia in this setting.

METHODS

Every woman 18 yr or older who underwent a non-elective Caesarean section under general anaesthesia was eligible to participate in this multicentre observational study. The primary endpoint was the incidence of hypoxaemia defined as the SpO₂ ≤95%. The secondary endpoint was the incidence of difficult intubation defined as more than two attempts or failed intubation.

RESULTS

During the study period, 895 women were prospectively included in 17 maternity hospitals, accounting for 79% of women who had general anaesthesia for non-elective Caesarean section. Maternal hypoxaemia was observed in 172 women (19%; confidence interval [CI], 17-22%). Risk factors associated with hypoxaemia in the multivariate analysis were difficult or failed intubation (adjusted odds ratio [aOR]=19.1 [8.6-42.7], P<0.0001) and BMI >35 kg m^-2 (aOR=0.53 [0.28-0.998], P=0.0495). Intubation was difficult in 40 women (4.5%; CI, 3.3-6%) and failed intubation occurred in five women (0.56%; CI, 0.1-1%). In the multivariate analysis, use of a hypnotic drug other than propofol was associated with difficult or failed intubation (aOR=25 [2-391], P=0.02). A propensity score confirmed that propofol was associated with a significant decreased risk of difficulty or failure to intubate (P<0.001).

CONCLUSIONS

Hypoxaemia during Caesarean sections was observed in 19% of women and was significantly associated with difficult or failed intubation. The use of propofol may protect against the occurrence of difficult intubation.

Comparison of electroencephalogram between propofol- and thiopental-induced anesthesia for awareness risk in pregnant women

There have been few comparative studies using electroencephalogram (EEG) spectral characteristics during the induction of general anesthesia for cesarean section. This retrospective study investigated the differences in the depth of anesthesia through EEG analysis between propofol- and thiopental-induced anesthesia. We reviewed data of 42 patients undergoing cesarean section who received either thiopental (5 mg/kg) or propofol (2 mg/kg). EEG data were extracted from the bispectral index (BIS) monitor, and 10-second segments were selected from the following sections: 1) Stage I, BIS below 60 after induction; 2) Stage II, after intubation completion; 3) Stage III, end-tidal sevoflurane above 0 vol%. The risk of awareness was represented by the BIS and entropy measures. In Stage III, the thiopental group (n = 20) showed significantly higher BIS value than the propofol group (n = 22) (67.9 [18.66] vs 44.5 [20.63], respectively, p = 0.002). The thiopental group had decreased slow-delta oscillations and increased beta-oscillations as compared to the propofol group in Stages II and III (p < 0.05). BIS, spectral entropy, and Renyi permutation entropy were also higher in the thiopental group at Stages II and III (p < 0.05). In conclusion, frontal spectral EEG analysis demonstrated that propofol induction maintained a deeper anesthesia than thiopental in pregnant women.

The influence of mode of anaesthesia for caesarean delivery on neonatal Apgar scores in the Czech Republic and Slovakia: secondary analysis of the results of an international survey in 2015

AIMS

The purpose of this international survey was to describe the impact of current practices and techniques of caesarean section on the neonatal Apgar score in the Czech Republic (CZE) and Slovakia (SVK).

METHODS

All Czech and Slovak departments that provide obstetric anaesthesia were invited to participate in a one-month (November 2015) prospective study that monitored in details all peripartum anaesthetic practices, delivered by anaesthesiologists. Participating centers recorded all data on-line in the CLADE-IS database (Masaryk University, CZE).

RESULTS AND DISCUSSIONS

We collected data of 10119 women who delivered 10226 newborns. A caesarean section was recorded in 25.1% of deliveries (CZE 23.2%; SVK 30%). General anaesthesia was used for caesarean section in 37.5% of the cases (CZE 40%, SVK 33%). There was no statistically significant difference in the Apgar score lower than 7 in the 1, 5 or 10 min in groups of general and regional anaesthesia for caesarean section, when only elective sections of in-term babies with birth weight over 2500 g were analyzed. We found no statistically significant differences in the Apgar score in newborns of women intubated for caesarean section in rocuronium (n=21; 2.2%) and suxamethonium (n=889; 93%).

CONCLUSION

We found no difference in neonatal outcomes in groups of general and regional anaesthesia for caesarean section when only out-of-risk newborns were analyzed. The risk factors were identified as follows: an acute caesarean section, preterm babies, birth weight less than 2 500 g, born in perinatological center and multiple pregnancy - second baby.

TRIAL REGISTRATION

ClinicalTrials.gov (ID: NCT02380586) https://clinicaltrials.gov/ct2/show/NCT02380586.

Using animal-derived constituents in anaesthesia and surgery: the case for disclosing to patients

BACKGROUND

Animal-derived constituents are frequently used in anaesthesia and surgery, and patients are seldom informed of this. This is problematic for a growing minority of patients who may have religious or secular concerns about their use in their care. It is not currently common practice to inform patients about the use of animal-derived constituents, yet what little empirical data does exist indicates that many patients want the opportunity to give their informed consent.

DISCUSSION

First we review the nature and scale of the problem by looking at the groups who may have concerns about the use of animal-derived constituents in their care. We then summarise some of the products used in anaesthesia and surgery that can contain such constituents, such as anaesthetic drugs, surgical implants and dressings. Finally, we explore the problem of animal-derived constituents and consent using Beauchamp and Childress' four principles approach, examining issues of autonomy, beneficence, nonmaleficence and justice. Disclosing the use of animal-derived constituents in anaesthesia and surgery is warranted under Beauchamp and Childress' four principles approach to the problem. Although there exist systemic and practical challenges to implementing this in practice, the ethical case for doing so is strong. The Montgomery ruling presents additional legal reason for disclosure because it entails that patients must be made aware of risks associated with their treatment that they attach significance to.

Current Modalities and Mechanisms Underlying Cardioprotection by Ischemic Conditioning

Ischemic preconditioning is a process which serves to mitigate reperfusion injury. Preconditioning of the heart can be achieved through natural, pharmacological, and mechanical means. Mechanical preconditioning appears to have the greatest chance of good outcomes while methods employing pharmacologic preconditioning have been largely unsuccessful. Remote ischemic preconditioning achieves a cardioprotective effect by applying cycles of ischemia and reperfusion in a distal limb, stimulating the release of a neurohumoral cardioprotective factor incited by stimulation of afferent neurons. The cardioprotective factor stimulates the reperfusion injury salvage kinase (RISK) and survivor activator factor enhancement (SAFE) signaling cascades in cardiomyocytes which promote cell survival by the expression of anti-apoptotic genes and inhibition of the opening of mitochondrial permeability transition pores. Clinical application of ischemic preconditioning involving targets in the RISK and SAFE signaling appears promising in the treatment of acute myocardial infarction; however, clinical trials have yet to demonstrate additional benefit to current therapy.

A survey of practice of rapid sequence induction for caesarean section in England

BACKGROUND

In view of newer techniques of preoxygenation and laryngoscopy and recent obstetric guidelines concerning the management of difficult intubation, we aimed to evaluate the current practice of rapid sequence induction for caesarean section in England.

METHODS

In 2017, 316 questionnaire surveys were posted to all 158 hospitals with caesarean section capabilities in England. At each hospital, one questionnaire was to be completed by the obstetric anaesthetic consultant lead and one by an anaesthetic trainee. Differences in responses between consultants and trainees, regardless of their place of work, were compared for all data using the chi-square and the Fisher's exact tests.

RESULTS

One-hundred-and-eighty complete questionnaires were returned, with an overall response rate of 57%, 98 (54%) from obstetric anaesthetic consultant leads and 82 (45.6%) from trainees). Both head up (57%) and ramped (56%) were the preferred positions for preoxygenation. Less than half of respondents (43%) preoxygenated until the surgeon was scrubbed. Cricoid pressure was used by almost all respondents (98%). Thiopentone (67%) was the most commonly chosen anaesthetic induction agent and most respondents (82%) supported a change to the use of propofol. Suxamethonium (92%) was the neuromuscular blocker of choice but more than half the respondents (52%) supported a change to rocuronium. In the event of a failed intubation, the rescue supraglottic airway device of choice was the i-gel® (65%).

CONCLUSIONS

Our survey demonstrated the significant variation in the practice of rapid sequence induction for caesarean section in obstetrics in the United Kingdom.

Obstetric Anaesthetists' Association and Difficult Airway Society guidelines for the management of difficult and failed tracheal intubation in obstetrics

The Obstetric Anaesthetists' Association and Difficult Airway Society have developed the first national obstetric guidelines for the safe management of difficult and failed tracheal intubation during general anaesthesia. They comprise four algorithms and two tables. A master algorithm provides an overview. Algorithm 1 gives a framework on how to optimise a safe general anaesthetic technique in the obstetric patient, and emphasises: planning and multidisciplinary communication; how to prevent the rapid oxygen desaturation seen in pregnant women by advocating nasal oxygenation and mask ventilation immediately after induction; limiting intubation attempts to two; and consideration of early release of cricoid pressure if difficulties are encountered. Algorithm 2 summarises the management after declaring failed tracheal intubation with clear decision points, and encourages early insertion of a (preferably second-generation) supraglottic airway device if appropriate. Algorithm 3 covers the management of the 'can't intubate, can't oxygenate' situation and emergency front-of-neck airway access, including the necessity for timely perimortem caesarean section if maternal oxygenation cannot be achieved. Table 1 gives a structure for assessing the individual factors relevant in the decision to awaken or proceed should intubation fail, which include: urgency related to maternal or fetal factors; seniority of the anaesthetist; obesity of the patient; surgical complexity; aspiration risk; potential difficulty with provision of alternative anaesthesia; and post-induction airway device and airway patency. This decision should be considered by the team in advance of performing a general anaesthetic to make a provisional plan should failed intubation occur. The table is also intended to be used as a teaching tool to facilitate discussion and learning regarding the complex nature of decision-making when faced with a failed intubation. Table 2 gives practical considerations of how to awaken or proceed with surgery. The background paper covers recommendations on drugs, new equipment, teaching and training.