Potential complications of spinal and epidural anesthesia for obstetrics.
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Biomedical subjects
Publications and source records attributed to M J Douglas.
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Lidocaine can be prepared in a variety of ways which may affect the characteristics of neural blockade achieved. Experimental evidence is equivocal as to the clinical impact of the use of different lidocaine preparations. A randomized, double-blind study was performed to investigate the differences in epidural anaesthesia for Caesarean section using three different lidocaine solutions: lidocaine CO2, two per cent lidocaine and two per cent lidocaine with its pH adjusted by the addition of bicarbonate. No differences were found among the groups in time of onset of neural blockade, quality or duration of neural blockade, time to delivery of the infant or volume of anaesthetic solution injected into the epidural space. A significant difference was found between the pH's of the solutions used. It is concluded that all three solutions are equally efficacious in epidural anaesthesia for Caesarean section.
Epidural sufentanil was administered to 57 women after Caesarean section, under epidural anaesthesia, to provide postoperative analgesia. Each patient received a 30 micrograms dose at the first complaint of pain and this dose was repeated when pain recurred. Epinephrine (1:200,000) was added to the local anaesthetic, sufentanil, both, or neither. The time of onset of analgesia, efficacy, duration of analgesia and the incidence of side-effects were recorded. This dose of epidural sufentanil provided satisfactory postoperative analgesia and no serious side-effects were observed. The onset of analgesia was rapid (4-6 min), but the duration of action was brief (4-5 hr). The addition of 1:200,000 epinephrine had no statistically significant influence on any of the measured variables. Pruritus occurred commonly but never required treatment. Drowsiness was experienced frequently and was felt by some patients to inhibit their interaction with their neonates. Respiratory depression, as defined by a respiratory rate less than 10 bpm, was not observed. A number of patients noted a transient period of euphoria 5-8 min after administration of the epidural sufentanil. The authors feel that epidural sufentanil provides satisfactory analgesia after Caesarean section, but the brief duration of action and the high incidence of drowsiness limit its acceptability for routine use in obstetric patients.
This retrospective study was undertaken to assess the efficacy and safety of epidural morphine in providing analgesia following Caesarean section under epidural anaesthesia. The morphine was administered as a single bolus, following delivery, in doses ranging from 2 to 5 mg. The charts of 4880 Caesarean sections, performed on 4500 patients, were reviewed. The duration of analgesia and the occurrence of any symptoms which might be side-effects of the epidural morphine were recorded. The duration of analgesia was 22.9 +/- 10.1 hr and was not correlated with the dose of epidural morphine. Eleven per cent of the patients required no supplemental analgesia during the first 48 hr. Twelve patients (0.25 per cent) had respiratory rates less than 10 breaths per minute, on at least one occasion. No serious sequelae resulted from these periods of bradypnoea. Pruritus occurred in 58 per cent of patients, nausea and vomiting in 39.9 per cent and dizziness in ten per cent. Herpes simplex labialis was recorded in 3.5 per cent of patients. Epidural morphine is thus confirmed as an effective analgesic technique post-Caesarean section with 3 mg being the optimal dose. Even in this young healthy patient population, clinically detectable respiratory depression occurs so clinical respiratory monitoring is indicated.
A case report is presented of a parturient who suffered severe hypotension and pulmonary oedema following an overdose of intramyometrial prostaglandin F2 alpha. Oxytocin induction of labour in this patient led to a rapid delivery, followed by a hypotonic uterus and postpartum haemorrhage. After resuscitation with blood and crystalloid fluids, the uterus was explored under general anaesthesia. The uterus was free of retained products but the lower uterine segment failed to contract despite bimanual uterine compression and intravenous oxytocin. Prostaglandin F2 alpha was injected into the lower uterine segment via a transvaginal approach. This was rapidly followed by cardiovascular collapse and later by pulmonary oedema. The differential diagnosis and subsequent management are discussed.
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Previous studies have reported that elevation of the pH of local anaesthetics results in more rapid onset of action, with enhanced quality and duration of block. This study investigated the effect of pH adjustment of 0.5 per cent bupivacaine immediately prior to epidural anaesthesia for Caesarean section. Addition of 0.1 ml of 8.4 per cent sodium bicarbonate to 20 ml of 0.5 per cent bupivacaine consistently raised the pH of the local anaesthetic from 5.49 to 7.04 (mean values). One hundred patients, presenting for elective Caesarean section under epidural anaesthesia participated in the study. Forty patients received epidural anaesthesia, using pH-adjusted 0.5 per cent bupivacaine, in a dosage adequate to produce block to the T4 level. A control group of 40 patients received the standard commercial preparation of 0.5 per cent bupivacaine. A further ten patients in each group received epidural anaesthesia using 0.5 per cent bupivacaine with the addition of 1:400,000 epinephrine, to study the effect of epinephrine on pH adjustment of the local anaesthetic. Elevation of the pH of the local anaesthetic significantly increased the speed of onset of action from 6.4 minutes to 3.2 minutes and the time to peak effect from 24.8 minutes to 18.1 minutes, while the duration of anaesthesia was increased from 124.8 minutes to 147.3 minutes. The time to S2 segment blockade was also shortened from 13.5 to 8.6 minutes. Addition of 1:400,000 epinephrine to the local anaesthetic did not influence the effect of pH adjustment. Maternal and umbilical cord plasma levels of bupivacaine were not affected by pH adjustment of the local anaesthetic, while MV/UV and UA/UV ratios were unaltered.
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The effect of the addition of bupivacaine to epidural morphine (EM) on postoperative analgesia was evaluated in 150 patients after cesarean section performed under epidural anesthesia with carbonated lidocaine. Fifty patients received 3 mg EM without bupivacaine, 50 received 3 mg EM with 0.125% bupivacaine, 25 received 5 mg EM without bupivacaine, and 25 patients received 5 mg EM with 0.125% bupivacaine. Patients were assessed for quality and duration of postoperative analgesia, as well as the incidence and severity of side effects. The addition of bupivacaine did not affect the quality or duration of analgesia afforded by EM and did not influence the incidence or severity of side effects. Furthermore, there was no statistically significant difference in the analgesia obtained by patients receiving 3- and 5-mg doses of EM with or without bupivacaine.
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An overall management plan for malignant hyperthermia susceptible (MHS) parturients is presented based on the experience of managing 14 of these patients. A summary of the pertinent features of their deliveries and care plus a case report of one of these parturients is described. Discussion centres around the problems of diagnosis of malignant hyperthermia susceptibility in pregnancy, the differential diagnosis and management of fever and tachycardia in a MHS parturient during labour and the use of dantrolene prophylaxis. Management of the MHS parturient in labour includes temperature and heart-rate monitoring, provision for cooling, and ready availability of a vapour-free anaesthetic machine. A large-bore intravenous infusion for hydration and for potential therapy of a MH crisis is essential. Epidural analgesia, using 2-chloroprocaine, is recommended. Emergency and elective Caesarean section anaesthesia are discussed. The importance of being prepared for a potential crisis is stressed with particular emphasis on early diagnosis by monitoring of temperature at two sites, of heart rate and rhythm with a continuous ECG and of end-tidal carbon dioxide, should a general anaesthetic be required. Recommendations are made for appropriate anaesthetic agents for both regional and general anaesthesia. Treatment of a MH crisis is outlined, with emphasis on availability of appropriate resuscitative drugs.
Hospitals and anaesthetists in British Columbia were surveyed by means of questionnaires to assess patterns of obstetric anaesthesia practice, qualifications and numbers of obstetric anaesthesia personnel, hospital obstetric facilities and facilities and protocols for neonatal resuscitation. It was apparent that a large proportion of the obstetric anaesthesia service in this province was being provided by physicians who were not trained, nor certified, as anaesthesia specialists. Preanaesthetic assessment in the obstetric units differed in attitude and practice from the standards expected in the general operating rooms. There was also in community hospitals a significant incidence of failure to follow certain accepted safe practices (in obstetric patients), such as preinduction hydration and oxygenation, cricoid pressure during intubation and prevention of aortocaval compression. However, administration of general anaesthesia without endotracheal intubation, was rare in this survey. Post-anaesthetic recovery facilities in obstetric units were conspicuously deficient, even in the larger hospitals. The majority of community hospitals lacked written protocols for neonatal resuscitation; and the number of institutions reporting that the neonatal heart rates and temperatures were not routinely monitored is of concern. It is recommended that minimum standards for training in obstetric anaesthesia should be clearly defined; and provision should be made for revision and upgrading of knowledge and skills for physicians practicing anaesthesia in smaller community hospitals.
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Previous studies have reported that elevation of the pH of local anaesthetics is associated with enhanced quality and duration of block. This study investigated the effect, on time to onset and duration of analgesia, of pH adjustment of 0.25 per cent bupivacaine immediately prior to injection into the epidural space in parturients. Addition of 0.1 ml of 8.4 per cent sodium bicarbonate to 20 ml of 0.25 per cent bupivacaine consistently raised the pH of the local anaesthetic from 5.65 to 7.26 (mean values). Thirty parturients received an epidural injection of 8 ml of pH-adjusted 0.25 per cent bupivacaine and a control group of 30 parturients received 8 ml of the standard commercial preparation of 0.25 per cent bupivacaine. Elevation of the pH of the local anaesthetic significantly increased the speed of onset of analgesia from 6.0 minutes to 3.2 minutes and the duration of analgesia was significantly lengthened from 79.4 minutes to 96.5 minutes. There was no significant influence on time to peak effect, nor on mean maternal plasma levels of bupivacaine.
The severity of epidural morphine-induced pruritus was evaluated following the addition of epinephrine to the local anaesthetic solution used for Caesarean section anaesthesia. The local anaesthetic solutions used were: Group I--0.5 per cent bupivacaine plain--20 patients. Group II--0.5 per cent bupivacaine with 1:400,000 epinephrine--25 patients. Group III--0.5 per cent bupivacaine with 1:200,000 epinephrine for the 3 ml "test dose" followed by 0.5 per cent bupivacaine plain for anaesthesia--21 patients. The severity of the pruritus, as measured by completion of a visual analogue "itch scale" and by requests for medication for pruritus, was statistically significantly greater in both groups in which epinephrine was added. This effect was not dose-related, as the "test dose" group (15 micrograms epinephrine) experienced the most severe itch. This latter difference was also statistically significant (p less than 0.05).
Using a double-bolus technique, the efficacy and safety of epidural fentanyl with and without epinephrine 1:400,000 for post-Caesarean section analgesia was examined in 30 patients. The addition of 25 micrograms epinephrine to the fentanyl (100 micrograms) did not potentiate the speed of onset but did significantly prolong the duration of action of the second dose. The only side effect encountered was pruritus, which was significantly increased (from 17-44 per cent) when epinephrine was added. The results indicate a clinical advantage of prolonging the duration of action of fentanyl for post-Caesarean Section analgesia with the addition of epinephrine, but the cumbersome and time-consuming nature of a double-bolus technique limits its clinical value. The relative safety of epidural fentanyl with and without epinephrine was confirmed by the absence of respiratory depression, drowsiness or hypotension in all patients.