PREVENTION OF HYPOTENSION FOLLOWING SPINAL ANAESTHESIA FOR ELECTIVE CAESAREAN SECTION BY WRAPPING OF THE LEGS

Twenty-four parturients undergoing elective Caesarean sectionwere allocated randomly to have the legs wrapped with elasticatedEsmarch bandages immediately following spinal anaesthesia orto serve as controls. Significant hypotension (systolic arterialpressure < 100 mm Hg and < 80% of baseline value) wastreated with i. v. ephedrine in 5-mg boluses. Leg wrapped patientshad a significantly (P = 0.0033) lower incidence (16.7%) ofhypotension than controls (83.3%). Only two patients in theleg wrapped group required ephedrine compared with 10 in thecontrol group. Systolic arterial pressure was significantly(P < 0.05) less in control subjects at 4, 5 and 6 min followingspinal injection. No patient in the leg wrapped group becamehypotensive following removal of the elasticated bandages.     

MATERNAL AND FETAL HAEMODYNAMIC EFFECTS OF SPINAL AND EXTRADURAL ANAESTHESIA FOR ELECTIVE CAESAREAN SECTION

Serial haemodynamic investigations were performed in 32 womenwho were allocated randomly to receive either spinal or extraduralanaesthesia for elective Caesarean section. Cardiac output wasmeasured by Doppler and cross-sectional echo-cardiography atthe aortic valve. Doppler flow velocity waveforms were recordedalso from the umbilical artery. Preloading with Ringer lactatesolution 1 litre increased cardiac output in both groups. Afterinjection of bupivacaine, cardiac output remained increasedin the extradural group, but decreased in the spinal group.This was associated with an increase in umbilical artery pulsatilityindex in the spinal group. Umbilical artery pH was less in thespinal group (7.22 vs 7.27). although no neonate was depressedat birth. The maximum percentage change in cardiac output andumbilical artery pulsatility index correlated with umbilicalartery pH (r = 0.54, r = 0.72, respectively). There was no significantcorrelation with change in arterial pressure.     

PERIDURAL SPINAL ANAESTHESIA FOR CAESAREAN SECTION

The technique of peridural spinal anaesthesia commonly used by the authors in Caesarean section is described. The advantages of this type of anaesthesia and its possibilities of success both as regards the mother and the foetus are considered. The conditions in which it may be contra-indicated, or in which the technique may prove unsuccessful, are discussed.     

COMPARISON OF INCREMENTAL SPINAL ANAESTHESIA USING A 32-GAUGE CATHETER WITH EXTRADURAL ANAESTHESIA FOR ELECTIVE CAESAREAN SECTION

Forty-three mothers who had requested regional anaesthesia forelective Caesarean section were allocated randomly to receiveeither extradural anaesthesia with pH-adjusted 2% lignocainewith 1/200 000 adrenaline, or incremental spinal anaesthesiausing a 32-gauge catheter with 0.5% plain bupivacaine. Incrementsof lignocaine or bupivacaine were given with the aim of achievinga block from T4 to S5. The spinal catheter was quicker to place(median 3 min, range 1–45 min, compared with median 10min, range 1.5–50 min) and spinal anaesthesia was quickerto establish (median 20 min, range 10–46 min comparedwith median 48 min, range 15–59 min) compared with theextradural technique. The maximum height of the spinal blockwas significantly higher (median T3–4, range T5–T3)than the extradural group (median T5, range T6–T3). Thetotal dose of intrathecal 0.5% bupivacaine was unpredictable,with a mean dose of 2.7 ml and a range between 1.5 ml and 7.4ml. Haemodynamic stability and the quality of the block weresimilar between the groups. There were two mild spinal headachesin the spinal group. All the spinal catheters were removed intact.     

INCREMENTAL SPINAL ANAESTHESIA FOR ELECTIVE CAESAREAN SECTION: MATERNAL AND FETAL HAEMODYNAMIC EFFECTS

We have performed serial haemodynamic investigations in 20 womenundergoing elective Caesarean section under continuous spinalanaesthesia with a 32-gauge catheter with 0.5% heavy bupivacaine.Cardiac output was measured by Doppler and cross-sectional echocardiographyat the aortic valve. Doppler flow velocity waveforms were recordedalso from the umbilical artery. A block to 74 or above was achievedin all patients. The median dose of 0.5% bupivacaine administeredwas 2.0 ml (range 1.5–4.5 ml). Mean cardiac output increasedfrom 7 to 8 litre min^-1 after preloading with Ringer lactatesolution 1.5 litre and then remained unchanged after injectionof bupivacaine. Two subjects developed hypotension, althoughmean values of arterial pressure and umbilical artery pulsatilityindex did not change. The median umbilical artery pH was 7.27(range 6.98–7.32) and there was a significant correlationbetween pH and the maximum percentage decrease in cardiac output.The results suggest that continuous spinal anaesthesia is associatedwith greater haemodynamic stability than single bolus spinalinjection. (Br. J. Anaesth. 1993; 70: 634–638)     

COMPLICATIONS OF SPINAL ANAESTHESIA FOLLOWING EXTRADURAL BLOCK FOR CAESAREAN SECTION

After extradural blockade failed to extend sufficiently forelective Caesarean section, spinal anaesthesia was performedusing 1.6 ml of hyperbaric 0.5% bupivacaine solution in 8% glucose(Marcain Heavy). The patient rapidly developed sensory blockadeto the level of T2, and became distressed and dyspnoeic. Generalanaesthesia was induced. Despite i.v. ephedrine and fluid loading,severe hypotension occurred, which responded subsequently tofurther doses of ephedrine and infusion of colloid. A healthyinfant was delivered by Caesarean section.     

BACTERIAL MENINGITIS FOLLOWING SPINAL ANAESTHESIA FOR CAESAREAN SECTION

We report a case of meningitis caused by inadvertent introductionof bacteria following spinal anaesthesia for Caesarean section.The technique of performing the spinal anaesthesia is reviewed.Meningitis may occur, although very rarely, despite meticulousaseptic techniques. It is vital that meningitis should be consideredin the differential diagnoses of post-spinal headache when patientspresent with headaches, pyrexia and meningism in the postoperativeor postpartum period.     

FETAL BLOOD FLOW DURING INTRATHECAL ANAESTHESIA FOR ELECTIVE CAESAREAN SECTION

Fetal aortic and umbilical blood flows were studied in 15 mothersbefore and during spinal (intrathecal) anaesthesia for electiveCaesarean section, using a method combining real-time ultrasonographyand a pulsed Doppler technique. Spinal anaesthesia with 0.5%bupivacaine hydrochloride 2.5ml in 8% glucose monohydrate solutionwas administered after preloading with 2 litre of lactated Ringer'ssolution. Simultaneously with the subarachnoid injection, aninfusion i. v. of ephedrine 50 mg in 500 ml normal saline wasinitiated. Maternal heart rate and systolic arterial pressureremained stable during the spinal anaesthesia, but diastolicarterial pressure decreased (P<0.05). Fetal heart rate increased(P<0.05) 30 min after the introduction of the spinal anaesthesia,but blood flows in the fetal descending aorta and umbilicalvein were unaffected. The pulsatility index of the fetal bloodvelocity decreased (P<0.05) both in the fetal aorta and inthe umbilical artery 30 min after induction of the spinal anaesthesia,indicating a possible decrease in the placental vascular resistance.We conclude that, when normotension is maintained in the motherwith a preload infusion and an infusion of ephedrine, spinalanaesthesia for Caesarean section has no harmful effect on thefetal circulation.     

PROPANIDID VERSUS THIOPENTONE FOR INDUCTION OF GENERAL ANAESTHESIA IN ELECTIVE CAESAREAN SECTION

A comparison was made of the Apgar scores of ninety-four neonatesborn by elective Caesarean section. Propanidid was used to induceanaesthesia in forty women and thiopentone in fifty-four. Anaesthesiawas maintained with nitrous oxide and muscle relaxants. Theincidence of neonatal depression was higher in the thiopentonegroup than in the propanidid group, particularly when induction-deliverytime was prolonged more than 10 minutes. This is attributedto the different fates of these drugs: propanidid is rapidlyhydrolyzed by esterases, while thiopentone is very slowly metabolizedin the liver.     

EXTRADURAL BUPIVACAINE OR LIGNOCAINE ANAESTHESIA FOR ELECTIVE CAESAREAN SECTION: THE ROLE OF MATERNAL POSTURE

Extradural anaesthesia was induced in 64 patients in eitherthe sitting or the lateral position, for elective Caesareansection with either 0.5% plain bupivacaine or 2% lignocainewith adrenaline 1 in 200 000. Onset was significantly shorterand a significantly greater number of patients were ready forsurgery within 35 min following injection of lignocaine in thelateral position. Hypotension (defined as a 25% or greater reductionin arterial pressure) occurred in 36% of patients. Significantlymore patients who had received the first injection of localanaesthetic agent in the sitting position required ephedrineto correct maternal hypotension. Most frequently, hypotensioncoincided with transfer of patients to theatre and thus wasassociated with movement of the patient in the presence of extensivesympathetic block.     

SPREAD OF SPINAL ANAESTHESIA FOR CAESAREAN SECTION IN SINGLETON AND TWIN PREGNANCIES

We have compared the spread of spinal anaesthesia in parturientswith singleton and those with twin pregnancies. Fifty-five unpremedicatedpatients with uncomplicated pregnancy scheduled for Caesareansection were allocated to two groups: group I = 35 singletonmothers; group II = 20 with twin pregnancy. Both groups receivedspinal anaesthesia with hyper baric bupivacaine 10 mg (2 mlof 0.5%). Mean birthweight was 3290 (SD 452) g and 5008 (495)g in groups I and II (combined birth weights), respectively.We found a statistically significant difference in onset andmaximal cephal-ad spread of spinal anaesthesia (group I median15, range 18–14; group II 13, range 16–12). Themechanisms of higher cephalad spread of spinal anaesthesia inparturients may be a decrease in cerebrospinal fluid volumesecondary to shunting of blood from the obstructed inferiorvena cava to the extradural venous plexus and increased nervesensitivity to local anaesthetics because of increased concentrationsof progesterone. The twin pregnancy group had heavier, largeruteri and greater daily production of progesterone. (Br. J.Anaesth. 1993; 70: 639–641)     

SPINAL ANAESTHESIA FOR CAESAREAN SECTION: The use of 0.5% bupivacaine

Subarachnoid anaesthesia was induced with 0.5% bupivacaine 2–3.5ml in 33 women scheduled for elective Caesarean section. Threepatients failed to develop adequate analgesia with bupivacainebut were managed satisfactorily with heavy cinchocaine. Allthe other patients developed adequate nnnlgirin eventually.Since the spread of analgesia was uniquely dependent on posturea new hypothesis is presented to explain the distribution ofintrathecal anaesthetic drugs in late pregnancy.     

THE USE OF TACRINE AND SUXAMETHONIUM IN ANAESTHESIA FOR CAESAREAN SECTION

Suxamethonium was combined with tacrine to obtain muscle relaxationin anaesthesia for Caesarean section in fifty patients. Themean total dose of suxamethonium used was 60 mg as against 400mg in thirty patients not given tacrine. The mean duration ofmuscle paralysis following suxamethonium 25 mg with tacrine20 mg was 14 minutes compared with 5.5 minutes after suxamethonium50 mg alone. Postoperative respiratory insufficiency of a milddegree occurred in one patient. Tacrine was found in specimensof urine from each of six neonates. Serious side effects inmother or child were not observed and this combination of drugswas thought worthy of further study for Caesarean section.     

EFFECT OF GRAVITY ON THE SPREAD OF EXTRADURAL ANAESTHESIA FOR CAESAREAN SECTION

The effect of gravity on the spread of extradural anaesthesiawas evaluated in a series of parturients undergoing electiveCaesarean section. Following placement of an extradural catheter,25 patients were placed 30–40° head-up for 20 minduring the administration of the local anaesthetic drug; 25additional patients remained supine during injection. Extraduralanaesthesia was induced with 3% 2-chloroprocaine 23 ml and analgesiato pinprick assessed at 5-min intervals. Additional drug wasgiven after 20 min, if required. There were no differences inthe rate of onset of sacral blockade or in the extent of neuralblockade between the two groups. The semi-upright position wasnot necessary to ensure adequate sacral anaesthesia for Caesareansection.     

A FURTHER STUDY OF GENERAL ANAESTHESIA FOR CAESAREAN SECTION

Methoxyflurane or trichloroethylene in concentrations of 0.2%or 0.1% used in anaesthesia for Caesarean section were compared.There were no differences in the acid-base state or the clinicalcondition of the infant at delivery, or in the incidence ofmaternal complications, which could be related to the choiceof volatile agent. Either volatile agent in the 0.2% concentrationwas associated with an overall incidence of maternal awarenessand unpleasant dreams of 2.5%, compared with 4.9% when the 0.1%concentration was used. The incidence of maternal nausea andvomiting was less in the 0.2% series. There was an apparentrelationship between the induction-delivery interval and (a)the degree of neonatal acidosis and (b) the Apgar-minus-colourscores at one minute ((A—C)₂). The correlation betweenthose indices of increasing foetal depression and increasinglength of the uterine incision-delivery interval was highlysignificant. There was no systematic relationshipbetween theone-minute score for "colour" and the umbilical artery Po₂.     

COMPARISON OF FOUR LOCAL EXTRADURAL ANAESTHETIC SOLUTIONS FOR ELECTIVE CAESAREAN SECTION

We have examined a combination of two local anaesthetics tosee if the resultant solution is superior to the agents individually.This study shows that a mixture of bupivacaine and lignocaineprovided an excellent alternative to bupivacaine alone, andwas superior to 2% lignocaine with adrenaline for elective Caesareansection. By reducing the dose of bupivacaine used, the combinationmay reduce the risk of cardiotoxicity. An account of the preliminary results of this study was presentedat the autumn meeting of the Obstetric Anaesthetists Association,held at the University of Warwick in September 1989. ^*Present address: Charing Cross Hospital, London W6. Present address: Brompton Hospital, London SW3. ^¶Present address: Harefield Hospital, Middx. Present address: Hillington Hospital, Middx.     

SPINAL ANAESTHESIA FOR CAESAREAN SECTION: Management of a parturient with severe cardiovascular disease

A parturient with severe mitral valve disease and pulmonaryoedema was admitted to the labour ward. Fetal distress was alsopresent. An emergency Caesarean section was undertaken underspinal blockade. The reasons for the choice of this techniqueare discussed     

ANAESTHESIA FOR SIMULTANEOUS CAESAREAN SECTION AND CLIPPING OF INTRACEREBRAL ANEURYSM

A 38-yr-old woman who was 35 weeks pregnant presented with asubarachnoid haemorrhage, secondary to a ruptured anterior communicatingartery aneurys. Following initial recovery, she subsequentlyunderwent simultaneous elective Caesarean section and clippingof the aneurysm. The anaesthetic management of the case is describedand discussed.     

AWARENESS FOLLOWING DIFFERENT TECHNIQUES OF GENERAL ANAESTHESIA FOR CAESAREAN SECTION

Using the isolated arm technique, the frequency of awarenesswas evaluated in 50 full-term patients undergoing elective Caesareansection under general anaesthesia. In 20 patients, anaesthesiawas induced with thiopentone 4 mg kg^–1, and in the other30 patients, induction was with ketamine 1.5 mg kg^–1.Following suxamethonium 1.5 mg kg^–1 and tracheal intubation,anaesthesia was supplemented during the induction—deliveryperiod in the thiopentone group with 50% nitrous oxide and 0.5%halothane in oxygen in 10 patients, and with 1% halothane in100% oxygen in the other 10 patients. In the ketamine group,the patients underwent ventilation with 50% nitrous oxide and0.5% halothane in oxygen in 10 patients, with 1% halothane in100% in 10 patients, and with 100% oxygen only in the last 10patients. Awareness was significantly greater after inductionwith thiopentone (14/20) than after ketamine (4/30). There wereno significant differences in Apgar scores or umbilical veinblood-gas values in the newborns.