Anticipated difficult airway during obstetric general anaesthesia: narrative literature review and management recommendations.

We reviewed the literature on management of general and regional anaesthesia in pregnant women with anticipated airway difficulty. We identified 138 publications comprising 158 cases; these either described equipment or techniques for the provision of general anaesthesia, or the management of women with regional analgesia or anaesthesia, with the aim of avoiding general anaesthesia. Most of the former group described women requiring caesarean section alone, or in combination with other surgery, which was sometimes airway-related. Management techniques were largely similar to those in non-obstetric patients requiring surgery who have airway difficulties, although suggested differences related to physiological changes of pregnancy and avoidance of nasal intubation. In the reports discussing regional anaesthesia, consideration was often given to the possible requirement for urgent out-of-hours anaesthetic intervention, and the predicted difficulty of management of general anaesthesia should it be required. In a number of reported cases, multidisciplinary planning led to the conclusion that elective caesarean section should be performed in order to avoid emergency airway management. Based on this literature review, we advise antenatal planning that includes: assessment of the patient's clinical characteristics; consideration of the equipment and personnel available to provide safe airway management out-of-hours; and elective caesarean section should these be lacking. If general anaesthesia is required, a risk assessment must be made as to the probability of safe airway management after the induction of anaesthesia, and awake tracheal intubation should be used if this cannot be assured. Decision aids are provided to illustrate these points. Online appendices include a comprehensive compendium of case reports on the management of a number of rare syndromes and airway conditions.

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.

Uncorrected total anomalous pulmonary venous drainage in pregnancy.

Total anomalous pulmonary venous drainage is a rare form of congenital heart disease. It usually presents in the neonatal period, although later presentation, including in adulthood, is known to occur. We could not find any accounts of adult survivors with the undiagnosed disease becoming pregnant. We describe the case of a 19-year-old Bengali primiparous woman who arrived in the UK at 27 weeks' gestation and needed an urgent caesarean section for intrauterine growth restriction at 34 weeks' gestation. Uncorrected congenital heart disease was diagnosed at this time although the exact nature of the pathology was not clear. She underwent an uncomplicated caesarean section using a combined spinal-epidural technique with invasive monitoring. Intrathecal 0.5% hyperbaric bupivacaine 0.7 mL and fentanyl 25 microg were sufficient for surgery. She remained cardiovascularly stable throughout the procedure and a female infant was successfully delivered. She underwent corrective cardiac surgery 14 months after delivery. To our knowledge, this is the first report of caesarean section in a patient with uncorrected total anomalous pulmonary venous drainage. In this case, regional anaesthesia was successfully used.

Failed tracheal intubation during obstetric general anaesthesia: a literature review.

We reviewed the literature on obstetric failed tracheal intubation from 1970 onwards. The incidence remained unchanged over the period at 2.6 (95% CI 2.0 to 3.2) per 1000 anaesthetics (1 in 390) for obstetric general anaesthesia and 2.3 (95% CI 1.7 to 2.9) per 1000 general anaesthetics (1 in 443) for caesarean section. Maternal mortality from failed intubation was 2.3 (95% CI 0.3 to 8.2) per 100000 general anaesthetics for caesarean section (one death per 90 failed intubations). Maternal deaths occurred from aspiration or hypoxaemia secondary to airway obstruction or oesophageal intubation. There were 3.4 (95% CI 0.7 to 9.9) front-of-neck airway access procedures (surgical airway) per 100000 general anaesthetics for caesarean section (one procedure per 60 failed intubations), usually carried out as a late rescue attempt with poor maternal outcomes. Before the late 1990s, most cases were awakened after failed intubation; since the late 1990s, general anaesthesia has been continued in the majority of cases. When general anaesthesia was continued, a laryngeal mask was usually used but with a trend towards use of a second-generation supraglottic airway device. A prospective study of obstetric general anaesthesia found that transient maternal hypoxaemia occurred in over two-thirds of cases of failed intubation, usually without sequelae. Pulmonary aspiration occurred in 8% but the rate of maternal intensive care unit admission after failed intubation was the same as that after uneventful general anaesthesia. Poor neonatal outcomes were often associated with preoperative fetal compromise, although failed intubation and lowest maternal oxygen saturation were independent predictors of neonatal intensive care unit admission.

Extradural haematoma in a patient following manual removal of the placenta under spinal anaesthesia: was the spinal to blame?

A postpartum patient with a history of epilepsy and lack of compliance with anticonvulsant medication presented with seizures following removal of the placenta under spinal anaesthesia. An acute posterior fossa extradural haematoma was diagnosed and evacuated uneventfully. The aetiology of the seizures and possible association of the haematoma with spinal anaesthesia are discussed.

Post-anaesthesia recovery care on the labour ward.

We conducted a questionnaire survey amongst midwives working in the labour wards of two hospitals within the Trent region. The results show that most of these midwives undertake the care of postoperative patients infrequently and have received little, if any, training. Also, most had not received any guidelines on which to base their practice. Over 80% observed respiratory rate, pulse rate, colour and manual blood pressure with approximately half measuring body temperature. In one hospital, over 90% used an automated blood pressure monitor and pulse oximeter. In the second hospital this happened in only 50% of cases. There appears to be some confusion regarding the monitors used postoperatively in that 11% of midwives said that they routinely used a capnometer in this situation.

Patients' assessment of sensory levels during epidural analgesia in labour.

Thirty women in established labour and with epidurals in situ were asked to assess the sensory level of the epidural using loss of light touch sensation with their own finger. This dermatomal level was then compared to the sensory level assessed by an anaesthetist using loss of cold sensation with ethyl chloride spray. A total of 88 assessments were made. The mean dermatomal difference was 0.20 and 95% of the differences lay between 3.5 and -3.1 dermatomes. This large variation in dermatomal differences between the two methods of sensory assessment means that patient light touch is not an acceptable method of assessing epidural sensory level when compared to ethyl chloride.

Gastric emptying after minor gynaecological surgery. The effect of anaesthetic technique.

Gastric emptying was measured using the paracetamol absorption method in 30 patients immediately after a general anaesthetic for minor gynaecological surgery and in 10 female controls. Anaesthesia was induced with either propofol alone, propofol and alfentanil (4.5 micrograms.kg-1) or propofol and fentanyl (1.4 micrograms.kg-1) and maintained with intermittent propofol and 66% nitrous oxide in oxygen. Gastric emptying was delayed significantly in all patient groups when compared with volunteers. However, the delay in gastric emptying was similar in the three patient groups.

Effect of sublingual buprenorphine on gastric emptying of a liquid meal.

The effect of buprenorphine 0.2 mg sublingually on gastric emptying of a liquid meal in 10 volunteers was compared with placebo. Gastric emptying was measured by applied potential tomography and was delayed significantly by buprenorphine (P less than 0.001).

A comparison of gastric emptying rate after cimetidine and ranitidine measured by applied potential tomography.

Gastric emptying was measured using applied potential tomography (APT) after crossover administration of 800 mg cimetidine and 300 mg ranitidine orally. Ten volunteers were studied, each on two occasions. Two hours after taking ranitidine or cimetidine, the volunteer was given a liquid and gastric emptying was measured over 60 min. There was a small but statistically significant delay in gastric emptying following ranitidine compared with cimetidine (P less than 0.04). The median (range) time to 50% emptying (t50) was 24 (15-60) min after ranitidine compared with 22 (15-46) min after cimetidine.

Effect of alcohol on gastric emptying in volunteers.

We have examined the effect of alcohol on the gastric emptying rate of a liquid meal in 10 volunteers. Each volunteer was allocated randomly to receive, on three occasions, no alcohol, 3 units or 6 units of alcohol. Gastric emptying was measured using applied potential tomography. The rate of gastric emptying as measured by the time to 50% emptying (T50) was delayed significantly (P < 0.01) after alcohol 6 units (median 45.0 min (range 19-90 min)) compared with control (23.0 min (13-36 min)) and there was little change after alcohol 3 units (25.5 min (10-65 min)) [corrected].