Assessment of block height for satisfactory spinal anaesthesia for caesarean section

We investigated block heights that anaesthetists considered adequate for caesarean section to proceed under spinal anaesthesia. During 3 months, 15 obstetric anaesthetists recorded block height to touch, pinprick or cold when spinal anaesthesia was considered satisfactory for caesarean section to proceed. Median (IQR [range]) block height for touch, pinprick, first cold and icy were: T10 (T7–T12 [T3–L1]); T5 (T4–T6 [C7–L1]); T5 (T4–T6 [C7–L1]); and T3 (T2–T4 [C7–L1]), respectively. Modalities were significantly correlated for: touch and cold, p = 0.0001; touch and icy, p = 0.0007; touch and pinprick, p = 0.0018; cold and icy, p < 0.0001; cold and pinprick, p = 0.0001; icy and pinprick, p < 0.0001. Pairwise comparisons showed differences between all modalities (p < 0.001) apart from pinprick and first cold (p = 0.94). All women had satisfactory anaesthesia despite 76 (81%) having a block to touch below T6. Single modality assessment of block height, particularly using touch, may erroneously indicate inadequate anaesthesia for caesarean section.     

Effect of delayed supine positioning after induction of spinal anaesthesia for caesarean section

BACKGROUND: The study tested the hypothesis that the incidence of hypotension during spinal anaesthesia for caesarean section is less in parturients who remain in the sitting position for 3 min compared with parturients who are placed in the modified supine position immediately after induction of spinal anesthesia. METHODS: Spinal anaesthesia was induced with the woman in the sitting position using 2.8 ml hyperbaric bupivacaine 0.5% at the L(3-4) or L(2-3) interspace. Ninety-eight patients scheduled for elective caesarean section under spinal anaesthesia were randomised to assume the supine position on an operating table tilted 10 degrees to the left (modified supine position) immediately after spinal injection (group 0, n=52) or to remain in the sitting position for 3 min before they also assumed the modified supine position (group 3, n=46). Isotonic saline 2-300 ml was given intravenously over 15 min before spinal injection followed by 15 ml/kg over 15-20 min after induction of spinal anaesthesia. If the systolic blood pressure decreased to less than 70% of baseline or to less than 100 mmHg or if there was any complaint of nausea, ephedrine was given in 5 mg boluses intravenously every 2 min. RESULTS: The blood pressure decreased significantly in both groups following spinal injection (P<0.001). Blood pressure variations over time differed significantly between the two groups (P<0.05). However, the incidence of maternal hypotension before delivery was similar in the two groups. The difference was caused by the time to the blood pressure nadir being significantly shorter in group 0 compared with group 3 (9.1+/-4.5 min vs. 11.7+/-3.7 min, P<0.01). Similar numbers of patients received rescue with ephedrine before delivery: 35 (67%) in group 0 vs. 26 (57%) in group 3 (NS). The mean total dose of ephedrine before delivery was 10.9 mg in group 0 vs. 9.2 mg in group 3 (NS). There were no differences in neonatal outcome between the two groups. CONCLUSION: At elective caesarean section, a 3-min delay before supine positioning does not influence the incidence of maternal hypotension after induction of spinal anaesthesia in the sitting position with 2.8 ml of bupivacaine 0.5% with 8% dextrose.     

Sensory testing of spinal anaesthesia for caesarean section: differential block and variability

BackgroundThe aim of this study was to determine if sensory block following spinal anaesthesia, measured with a range of devices, corresponded to the hierarchy of nerve fibre size in the area of differential block, and to compare the distribution and variability of recorded measurements.MethodsWomen with singleton pregnancies >36 weeks of gestation undergoing elective caesarean section under combined spinal–epidural anaesthesia were recruited. An identical spinal anaesthetic was given to all. A single researcher with no clinical role assessed block height at 20 min from the time of spinal injection. Six tests were used in random order to measure four sensory modalities: ethyl chloride (cold), calibrated Neuropen (sharp), standardized monofilament 10 g (pressure), Neurotip stroking (light touch), monofilament stroking (light touch), cotton wool (light touch). The cost of each method of testing was noted.ResultsThe median differences between the four modalities were significant (Friedman test, P < 0.0001), but paired tests failed to find significant differences between Neuropen (sharp) and monofilament (pressure), monofilament (pressure) and Neurotip (light touch), and between tests for light touch. The tests for light touch had the least dermatomal spread and produced a unimodal distribution. The coefficient of variation was highest with ethyl chloride (24.1%) and the lowest with cotton wool (10.4%).ConclusionsSensory fibre hierarchy could be identified. Tests for light touch showed the least variability. More expensive tests do not appear to have any advantage over the least expensive test, cotton wool.     

Combined spinal epidural anaesthesia for elective caesarean section in a patient with spondylometaphyseal dysplasia

A patient with spondylometaphyseal dysplasia, an extremely rare form of dwarfism, presented for elective caesarean section. We report the successful management under regional anaesthesia, using a combined spinal epidural technique. There seem to be only two previous reports of spinal anaesthesia and there are no previous reports of the use of combined spinal epidural in a pregnant dwarf. Regional anaesthesia is thought to be complex in these dwarfs due to vertebral malformation and unpredictable anatomy of the spinal canal. They may present difficulties with intubation as well. Spondylometaphyseal dysplasia is reviewed and its anaesthetic implications discussed.     

Comparison of pentastarch and Hartmann's solution for volume preloading in spinal anaesthesia for elective caesarean section

We studied 160 patients undergoing elective Caesarean section under spinal anaesthesia who received a preloading volume of 15 ml kg-1 of 10% pentastarch in 0.9% saline, or Hartmann's solution, in a prospective, randomized, double-blind study. We compared the incidence of spinal-induced hypotension in each group. Hypotension was defined as a decrease in systolic arterial pressure to less than 70% of baseline values or < or = 90 mm Hg, whichever was the greater. The groups were comparable in physical characteristics and there was no serious morbidity. Fetal outcome was similar in both groups. Significantly more patients in the Hartmann's group (n = 38, 47.5%) developed hypotension than in the pentastarch group (n = 10, 12.5%) (P < 0.0001). Linear regression analysis showed that the only significant variable was type of fluid used. Blood glucose concentrations were not related to the presence of hypotension. We conclude that starches may be suitable for preloading in Caesarean section under spinal anaesthesia and provide an alternative to the aggressive use of vasoconstrictors.      

The effect of prophylactic glycopyrrolate on maternal haemodynamics following spinal anaesthesia for elective caesarean section

We conducted a randomised controlled trial to compare the severity of hypotension and ephedrine requirements following spinal anaesthesia for elective caesarean section in women pretreated with either i.v. glycopyrrolate 4.0 microg/kg (group G) or saline (group S). Data were analysed using sequential analysis which allowed us to terminate the study after data from 40 patients had been analysed (20 in each group). There were no differences between the two groups in the severity of hypotension (mean +/- SD decrease from baseline 35 +/- 14% in group G and 29 +/- 15% in group S) or ephedrine requirements (15 +/- 11 mg in group G and 18 +/- 12 mg in group S). Intra-operative heart rate increased by a greater amount in group G than in group S (58 +/- 26% vs 35 +/- 21% mean +/- SD;P = 0.002) and there was a greater incidence of dry mouth (75% vs 15%;P = 0.0006) but no difference in the incidence of nausea and vomiting (30% vs 50%;P = 0.33). Pretreatment with glycopyrrolate did not confer an advantage in this study.     

A comparison between epidural anaesthesia using alkalinized solution and spinal (combined spinal/epidural) anaesthesia for elective caesarean section

In a double-blind investigation, 40 women undergoing elective lower segment caesarean section were randomly divided into two groups. Group I (n = 20) received spinal anaesthesia with 2.0 ml hyperbaric 0.5% bupivacaine using a single space combined spinal epidural technique. Group II (n = 20) received epidural anaesthesia with a local anaesthetic mixture consisting of 0.5% bupivacaine plain 10 ml and 2% lignocaine plain 10 ml to which was added 0.1 ml of adrenaline 1 in 1000 and 2 ml of 8.4% sodium bicarbonate. The mean onset times of sensory block to T4 and grade 3 motor blockade were 7.9 min and 9.5 min respectively in the spinal group, compared to 13.1 min and 16.3 min in the epidural group. These differences were both significant (P < 0.05). There was no difference between the two groups in the quality of analgesia or the incidence of hypotension and nausea. The relatively rapid onset of the pH adjusted epidural solution may provide an attractive alternative to spinal anaesthesia. Moreover, this study underlines the important role of pH adjusted epidural solutions in parturients progressing to emergency caesarean section with epidural catheters previously inserted for labour analgesia.     

Cardiac arrest complicating spinal anaesthesia for caesarean section

We present a 36-year-old multiparous woman who developed intractable hypotension and cardiac arrest during spinal anaesthesia for elective caesarean section. Cardiopulmonary resuscitation was successful and both mother and baby made a good recovery. Postoperative investigation revealed a dilated cardiomyopathy related to pregnancy. This case highlights the importance of expediting delivery of the neonate during maternal cardiopulmonary resuscitation, the prompt use of adrenaline as inotropic support, and preoperative assessment in apparently healthy parturients.     

Thromboembolic deterrent stockings fail to prevent hypotension associated with spinal anaesthesia for elective caesarean section

This study was carried out to determine whether the use of thrombo-embolic deterrent (TED) stockings, in combination with an intravenous crystalloid preload, would prevent hypotension following spinal anaesthesia for caesarean section. Fifty parturients undergoing elective caesarean section under spinal anaesthesia were randomly allocated into two groups. TED stockings were applied to the study group 1 h before spinal anaesthesia but none were applied to the control group. Both groups received a crystalloid preload of 15 ml kg(-1) over 15 min before spinal injection. Significant hypotension, defined as an absolute value of systolic arterial pressure (SAP) of less than 90 mmHg and a decrease of more than 20% from baseline SAP was treated with 3 mg bolus of ephedrine as required. The difference in SAO between the two groups was not statistically significant. In the control group, 80% of parturients required ephedrine as opposed to 56% in the TED group; a difference that was also not statistically significant.     

Supraventricular tachycardia during spinal anaesthesia for caesarean section

A woman of 40 weeks' gestation, who was apparently previously healthy, required emergency caesarean section after a failed vacuum delivery. While under spinal anaesthesia she developed a supraventricular tachycardia of unknown origin. Intravenous verapamil resulted in a conversion to sinus rhythm. Further investigations confirmed Wolff-Parkinson-White syndrome, for which she required ablation therapy. Appropriate methods of cardioversion in this clinical setting are discussed.