Felicity Reynolds

Damage to the conus medullaris following spinal anaesthesia

Seven cases are described in which neurological damage followed spinal or combined spinal‐epidural anaesthesia using an atraumatic spinal needle. All patients were women, six obstetric and one surgical. All experienced pain during insertion of the needle, which was usually believed to be introduced at the L2−3 interspace. In all cases, there was free flow of cerebrospinal fluid before spinal injection. There was one patchy block but, in the rest, anaesthesia was successful. Unilateral sensory loss at the levels of L4–S1 (and sometimes pain) persisted in all patients; there was foot drop in six and urinary symptoms in three. Magnetic resonance imaging showed a spinal cord of normal length with a syrinx in the conus (n = 6) on the same side as both the persisting clinical deficit and the symptoms that had occurred at insertion of the needle. The tip of the conus usually lies at L1−2, although it may extend further. Tuffiers line is an unreliable method of identifying the lumbar interspaces, and anaesthetists commonly select a space that is one or more segments higher than they assume. Because of these sources of error, anaesthetists need to relearn the rule that a spinal needle should not be inserted above L3.

Anaesthesia for Caesarean section and neonatal acid-base status: a meta-analysis.

Spinal anaesthesia is generally preferred for Caesarean section. Its superiority for the baby is often assumed. Umbilical artery acid‐base status provides a valid index of fetal welfare. Twenty‐seven studies reporting neonatal acid‐base data with different types of anaesthesia were used to compare umbilical artery or vein pH and base deficit, using random‐effect meta‐analysis. Cord pH was significantly lower with spinal than with both general (difference: −0.015; 95% CI −0.029 to −0.001; 13 studies, 1272 subjects) and epidural anaesthesia (difference −0.013; 95% CI −0.024 to −0.002; 11 studies, 828 subjects). Larger doses of ephedrine contributed to the latter effect (p = 0.023). Sixteen studies reported a base deficit, which was significantly higher for spinal than for general (difference 1.109; 95% CI 0.434–1.784 mEq.l−1; seven studies, 695 subject) and epidural anaesthesia (difference 0.910; 95% CI 0.222–1.598 mEq.l−1; seven studies, 497 subjects). Spinal anaesthesia cannot be considered safer than epidural or general anaesthesia for the fetus.

Dural puncture and headache.

Accidental durai puncture during attempted epidural catheterisation, and headache following spinal blockade, have both attracted attention in the past decade, the former because it is a potent cause of morbidity, the latter because the reintroduction of atraumatic needles has led to a resurgence of spinal anaesthesia in obstetrics.

Caesarean section in Malawi: prospective study of early maternal and perinatal mortality

Abstract Objective To examine potentially modifiable factors that may influence the high maternal and perinatal mortality associated with caesarean section in Malawi. Design A prospective observational study of 8070 caesarean sections performed between January 1998 and June 2000 and associated complications. Setting 23 district and two central hospitals in Malawi. Participants 45 anaesthetists from hospitals that carried out caesarean sections. Main outcome measures Associations between maternal or perinatal deaths in the first 72 hours and various quantifiable risk factors. Results Questionnaires were returned for 5236 caesarean sections in district hospitals and 2834 in central hospitals; 7622 (94%) were emergencies, 5110 (63%) were because of obstructed labour. Preoperative haemorrhagic shock was present in 610 women (7.6%), anaemia in 503 (6.2%), and ruptured uterus in 333 (4.1%). Eighty five women died (1.05%), 68 of whom died postoperatively on the wards. Higher maternal mortality was associated with ruptured uterus (adjusted odds ratio 2.3, 95% confidence interval 1.3 to 4.0), little anaesthetic training (2.9, 1.6 to 5.1), general as opposed to spinal anaesthesia (6.6, 2.3 to 18.7), and blood loss requiring transfusion of ≥2 units (21.0, 11.7 to 37.7). Perinatal mortality up to 72 hours was 11.2% overall and was significantly associated with ruptured uterus and general rather than spinal anaesthesia. Conclusion In sub-Saharan Africa high maternal and perinatal mortality at caesarean section is associated with major preoperative complications that are unusual in developed countries. Improved training in anaesthetics, wider use of spinal anaesthesia, and improved surveillance and resuscitation in postoperative wards might reduce mortality.

Upper oesophageal sphincter pressure and the effect of cricoid pressure

Upper oesophageal sphincter pressure has been measured in 24 patients with a sleeve device. The median sphincter pressure when awake was 38 mmHg. and when anaesthetised and paralysed was 6 mmHg. After tracheal intubation, cricoid pressure was applied at measured values between 5 and 50 N using a hand‐held cricoid yoke while the sphincter pressure was recorded in two head and neck positions: with and without a standard intubating pillow with neck support. A cricoid force of 40 N increased sphincter pressure to above 38 mmHg in all the patients and the use of the pillow did not alter this effect. With the application of cricoid pressure, operating department assistants raised sphincter pressure to above 38 mmHg in only 50% of patients. Laryngoscopy made little difference to the effect of cricoid pressure except in one patient in whom it reduced the sphincter pressure by 27 mmHg.

Long term backache after childbirth: prospective search for causative factors

Abstract Objectives: To assess in a prospective randomised study the association between motor block resulting from high and low dose epidural infusions of bupivacaine in labour and the incidence of long term backache after childbirth, and to compare the incidence of backache in women not receiving epidural analgesia. Design: Women requesting epidural analgesia in labour between October 1991 and March 1994 were randomised to receive infusions of either bupivacaine alone or low dose bupivacaine with opioid. Data were collected during labour and the immediate postpartum period from these women and from women recruited at random over the same time from those who had laboured without epidural analgesia. A postal questionnaire about symptoms was sent three months after childbirth to all women. Further data were collected one year after childbirth from those who had reported new backache at three months. Setting: St Thomass Hospital, London. Subjects: 599 women were recruited, of whom 450 (75%) replied to a follow up questionnaire. Results: 152 women (33.8% of responders) reported backache lasting three months after delivery and, of these, 33 (7.3%) had not previously suffered with backache. There were no significant differences between the treatment groups in the incidence of postnatal backache overall or of new backache or any symptoms after childbirth. Among all demographic, obstetric, and epidural variables examined the only factors significantly associated with backache after childbirth were backache before and during pregnancy. Conclusions: The incidence of new long term backache was not significantly increased in women who received epidural analgesia in labour. Motor block resulting from epidural local anaesthetic administration was not a significant factor in the development of backache. Key messages About half of all women suffer backache during pregnancy, but many forget this when questioned retrospectively A prospective study showed that the incidence of new postpartum backache is 7.3 The use of epidural analgesia in labour had no effect on the incidence of postpartum backache In a randomised trial motor block in labour was not associated with an increase the incidence of backache

Accidental dural puncture rates in UK obstetric practice

Headache following epidural analgesia is a common cause of complaint, but accidental dural puncture rates vary among hospitals and with techniques. We were therefore interested to discover the extent of audit of dural puncture, the dural puncture rates in those UK centres that kept reliable records, and the techniques they used for detecting the epidural space. Consultants in charge of anaesthetic services to all 257 obstetric units in the UK were sent a questionnaire requesting numbers of obstetric epidurals, techniques used to detect the epidural space and the numbers of accidental dural punctures in the years 1991-1995. Replies were received from 191 respondents (74%) of whom 104 were able to provide some information about dural puncture rates. Dural puncture rate was inversely related to the number of epidurals performed; the highest recorded rate was 3.6% in a unit with < 300 epidurals annually, and the lowest 0.19% in a unit with > 1000. Most respondents did not record the loss of resistance technique used but among those who did, the dural puncture rate using mainly saline was 0.69% and using mainly air was 1.11% (P<0.001). Since accurate patient information is crucial for informed consent, audit needs to be improved in many centres. Though the accidental dural puncture rate may be under-reported in this survey, our data are in agreement with other findings that loss of resistance to saline is safer than loss of resistance to air.

The subdural space: the third place to go astray

Subdural placement of the tip of the Tuohy needle or epidural catheter may account for many unexpected complications of attempted epidural blockade, for example ‘unexplained’ headache, false‐negative aspiration test down needle or catheter, false‐negative test dose, unilateral block, delayed total spinal and neurological sequelae, as well as profound block of delayed onset that is characteristic of subdural blockade. Cases are reported in support of this hypothesis.

Assessing long term backache after childbirth.

OBJECTIVES--To investigate the factors associated with long term backache after childbirth, to assess all women reporting new onset long term backache, and to investigate any relation with pain relief in labour. DESIGN--Data collected from obstetric records and postal questionnaires or telephone interviews on morbidity after childbirth from all women delivering their first baby between March 1990 and February 1991, followed by analysis of data collected from outpatient consultations. SETTING--St Thomass Hospital, London. SUBJECTS--Questionnaires were sent to 1615 women who had delivered their first baby in the defined period; 1015 either replied by post or were contacted by telephone. RESULTS--299 women (29.5% of responders) reported backache lasting more than six months and of these 156 (15.4%) said they had had no back problems previously. Those women who had received epidural analgesia in labour were significantly more likely to report new onset backache (17.8%; 95% confidence interval 14.8% to 20.8%) than those who did not (11.7%; 8.6% to 14.8%). Younger women, unmarried women, and those reporting other antenatal symptoms were significantly more likely to report new long term backache. The 156 women reporting new backache were asked to attend an outpatient clinic and 36 (23%) did so. The majority had a postural backache which was not severe. Psychological factors were present in 14 women. CONCLUSIONS--Though new long term backache is reported more commonly after epidural analgesia in labour, it tends to be postural and not severe. There were no differences in the nature of the backache between those who had or had not received epidural analgesia in labour.

Analgesia in labour and fetal acid–base balance: a meta-analysis comparing epidural with systemic opioid analgesia

Objective To assess the effect of epidural versus systemic labour analgesia on funic acid–base status at birth.