Comparison of phenylephrine infusion regimens for maintaining maternal blood pressure during spinal anaesthesia for Caesarean section

Background. During spinal anaesthesia for Caesarean section,the optimal phenylephrine regimen and the optimal blood pressure(BP) to which it should be titrated are undetermined. The idealregimen would balance efficacy for maintaining uteroplacentalperfusion pressure against potential for uteroplacental vasoconstriction,both of which may affect fetal acid–base status. We comparedphenylephrine infusion regimens based on three different BPthresholds. Methods. After intrathecal injection, we infused phenylephrine100 µg min^–1 for 2 min. Then, until delivery,we infused phenylephrine whenever systolic BP (SBP), measuredevery 1 min, was below a randomly assigned percentage of baseline:100% (Group 100, n=25), 90% (Group 90, n=25) or 80% (Group 80,n=24). We compared umbilical blood gases, Apgar scores and maternalhaemodynamics and symptoms. Results. Patients in Group 100 had fewer episodes [median 0(range 0–8)] of hypotension (SBP <80% baseline) comparedwith Group 80 [5 (0–18)] and Group 90 [2 (0–7)](P<0.001 in each instance). Total dose of phenylephrine wasgreater in Group 100 [median 1520 µg (interquartile range1250–2130 µg)] compared with Group 90 [1070 (890–1360)µg] and Group 80 [790 (590–950) µg]. Umbilicalarterial pH was greater in Group 100 [mean 7.32 (95% confidenceinterval 7.31–7.34)] than in Group 80 [7.30 (7.28–7.31)](P=0.034). No patient had umbilical arterial pH <7.2. InGroup 100, 1/24 (4%) patients had nausea or vomiting comparedwith 4/25 (16%) in Group 90 and 10/25 (40%) in Group 80 (P=0.006). Conclusions. For optimal management, phenylephrine should betitrated to maintain maternal BP at near-baseline values. Br J Anaesth 2004; 92: 469–74     

Subarachnoid haemorrhage following spinal anaesthesia in an obstetric patient

We describe an obstetric patient who presented for removal ofa retained placenta. After insertion of the spinal anaesthetic,she developed a severe headache, and a subarachnoid haemorrhagewas diagnosed. We discuss the differential diagnosis of theheadache, the occurrence of intracranial haemorrhages afterdural puncture and the future management of this patient. Br J Anaesth 2001; 86: 442–4     

Evaluation of pre-emptive intramuscular phenylephrine and ephedrine for reduction of spinal anaesthesia-induced hypotension during Caesarean section

Pre-emptive intramuscular (i.m.) vasopressors were evaluatedin 108 patients undergoing elective Caesarean section underspinal anaesthesia, assigned to four groups in a randomized,double-blind, placebo-controlled study. Group 1 received pre-emptivephenylephrine 4 mg i.m., group 2 received phenylephrine 2 mgi.m., group 3 received ephedrine 45 mg i.m., while controlsreceived an i.m. injection of saline, all given immediatelyafter induction of spinal anaesthesia. Hypotension was definedas a 25% decrease in mean arterial pressure (MAP). Rescue intravenous(i.v.) boluses of ephedrine were given if the patient was hypotensiveor reported nausea, vomiting or dizziness. The incidence ofhypotension was 33% in the phenylephrine 4 mg group comparedwith 70% in the control and phenylephrine 2 mg groups (P=0.03),and 48% in the ephedrine 45 mg group. The phenylephrine 4 mgand ephedrine 45 mg groups had a significantly lower percentagereduction in MAP (–21 (SD 14)% and –22 (14)%) comparedwith controls (–32 (18)%, P=0.04). They also had a lowertotal dose of rescue i.v. ephedrine (15.7 (15.7) mg and 15.8(15.6) mg) compared with controls (28.8 (20.6) mg, P=0.02).We conclude that pre-emptive i.m. phenylephrine 4 mg and ephedrine45 mg reduce the severity of hypotension and the total doseof rescue i.v. ephedrine during spinal anaesthesia for Caesareansection. Br J Anaesth 2001; 86: 372–6     

Haemodynamic effects of oxytocin given as i.v. bolus or infusion on women undergoing Caesarean section

Background. The cardiovascular effects of oxytocin in animalmodels and women undergoing Caesarean section include tachycardia,hypotension and decrease in cardiac output. These can be sufficientto cause significant compromise in high-risk patients. We aimedto find a simple way to decrease these risks whilst retainingthe benefits of oxytocin in decreasing bleeding after delivery. Method. We recruited 30 women undergoing elective Caesareansection. They were randomly allocated to receive 5 u of oxytocineither as a bolus injection (bolus group) or an infusion over5 min (infusion group). These women had their heart rate andintra-arterial blood pressure recorded every 5 s throughoutthe procedure. The haemodynamic data, along with the estimatedblood loss, were compared between the groups. Results. Marked cardiovascular changes occurred in the bolusgroup; the heart rate increased by 17 (10.7) beats min^–1[mean (SD)] compared with 10 (9.7) beats min^–1 in theinfusion group. The mean arterial pressure decreased by 27 (7.6)mm Hg in the bolus group compared with 8 (8.7) mm Hg in theinfusion group. There were no differences in the estimated bloodloss between the two groups. Conclusion. We recommend that bolus doses should be used withcaution, and further studies should ascertain if oxytocin isequally effective in reducing blood loss when given at a slowerrate.     

Small-dose selective spinal anaesthesia for short-duration outpatient gynaecological laparoscopy: recovery characteristics compared with propofol anaesthesia

A randomized controlled trial compared recovery characteristicsafter selective spinal anaesthesia (SSA) or propofol generalanaesthesia (GA) for short-duration outpatient laparoscopicsurgery. Forty women were randomized to receive either SSA (1%lidocaine 10 mg, sufentanil 10 µg and sterilewater 1.8 ml) or GA (propofol and nitrous oxide 50% inoxygen). Compared with the GA group, times to leaving the operatingroom, performing a straight leg raise, performing deep knee-bendsand achieving an Aldrete score >9 and the time in Phase IIrecovery were significantly shorter (P<0.05) in the SSA group. Br J Anaesth 2001; 86: 570–2     

Cranial subdural haematoma after spinal anaesthesia

Intracranial subdural haematoma is an exceptionally rare complicationof spinal anaesthesia. A 20-yr-old male underwent appendicectomyunder partial spinal and subsequent general anaesthesia. A weeklater, he presented with severe headache and vomiting not respondingto bed rest and analgesia. Magnetic resonance imaging showeda small acute subdural haematoma in the right temporo-occipitalregion. The patient improved without surgical decompression.The pathogenesis of headache and subdural haematoma formationafter dural puncture is discussed and the literature brieflyreviewed. Severe and prolonged post-dural puncture headacheshould be regarded as a warning sign of an intracranial complication. Br J Anaesth 2001; 86: 893–5     

Sequential compression device with thigh-high sleeves supports mean arterial pressure during Caesarean section under spinal anaesthesia

Background. This study investigated the use of a SequentialCompression Device (SCD) with thigh-high sleeves and a presetpressure of 50 mm Hg that recruits blood from the lower limbsintermittently, as a method to prevent spinal hypotension duringelective Caesarean section. Possible association of arterialpressure changes with maternal, fetal, haemodynamic, and anaestheticfactors were studied. Methods. Fifty healthy parturients undergoing elective Caesareansection under spinal anaesthesia were randomly assigned to eitherSCD (n=25) or control (n=25) groups. A standardized protocolfor pre-hydration and anaesthetic technique was followed. Hypotensionwas defined as a decrease in any mean arterial pressure (MAP)measurement by more than 20% of the baseline MAP. Systolic (SAP),MAP and diastolic (DAP) arterial pressure, pulse pressure (PP),and heart rate (HR) were noted at baseline and every minuteafter the spinal block until delivery. Results. A greater than 20% decrease in MAP occurred in 52%of patients in the SCD group vs 92% in the control group (P=0.004,odds ratio 0.094, 95% CI 0.018–0.488). There were no significantdifferences in SAP, DAP, HR, and PP between the groups. Conclusion. SCD use in conjunction with vasopressor significantlyreduced the incidence of a 20% reduction of MAP. Br J Anaesth 2003; 91: 695–8     

Randomized controlled study of colloid preload before spinal anaesthesia for caesarean section

We randomized women having elective Caesarean section to receiveeither no preload (control group, n=33) or 4% gelatin solution(Gelofusine) 15 ml kg^–1 (colloid group, n=35)i.v. before spinal anaesthesia. Intravenous metaraminol wastitrated at 0.25–0.75 mg min^–1 to maintainsystolic arterial pressure (SAP) in the target range 90–100%of baseline after the spinal injection. The control group requiredmore vasopressor in the first 10 min [median 1.7 (range 0–2.9)mg vs 1.4 (0–2.8), P=0.02] at a greater maximum infusionrate [0.5 (0–0.75) vs 0.25 (0–0.5) mg min^–1,P=0.0005] and had a lower minimum SAP [90 (51–109) vs101 (75–127) mm Hg, P=0.006] than the colloid group. Nauseawas less frequent in the colloid group (6 vs 24%) but neonataloutcome was similar in the two groups. Colloid preload improvedhaemodynamic stability but did not affect neonatal outcome whenarterial pressure was maintained with an infusion of metaraminolduring spinal anaesthesia for Caesarean section. Br J Anaesth 2001; 87: 772–4     

Assessment of pulse transit time to indicate cardiovascular changes during obstetric spinal anaesthesia

Background. Pulse transit time (PTT) measurement may providerapidly available beat-to-beat cardiovascular information whenconditions change quickly and routine invasive arterial pressuremeasurement is not justified, for example during obstetric spinalanaesthesia. Method. We obtained ethics approval for an observational studyof PTT during the onset of spinal anaesthesia in patients havingelective or urgent Caesarean section. PTT was measured as thedifference in time between the peak of the ECG R wave and theupstroke of the toe plethysmograph. Arterial pressure was measuredby non-invasive sphygmomanometry. Results. We analysed data from 58 normotensive patients and15 patients with pregnancy-induced hypertension (PIH). PTT increasedwith the onset of spinal anaesthesia as arterial pressure decreased.An increase of 20% in PTT was 74% sensitive and 70% specificin indicating a decrease in mean arterial pressure of more than10%. Changes in PTT were related to changes in mean arterialpressure (r²=0.55, P<0.0001). Arterial pressure changes weregreater and PTT increased significantly more quickly in thenormotensive patients than in the patients with hypertension[median, quartiles: 32 (14, 56) ms min^–1 compared with7 (6, 18) ms min^–1; P<0.01, Mann–Whitney U-test].However, the relationship between PTT and arterial pressurewas similar for the normotensive patients and the patients withPIH. Conclusion. PTT measurement gave a beat-to-beat indication ofarterial pressure during spinal anaesthesia, and could be developedto allow prediction of the onset of hypotension. Data from this study were presented in part at the ObstetricAnaesthetists Association Meeting at Nottingham, UK, on May10, 2002 and at the 13th World Congress of the InternationalSociety for the Study of Hypertension in Pregnancy at Toronto,Canada, on June 2, 2002.     

Effect of preoperative amino acid infusion on thermoregulatory response during spinal anaesthesia

Background. Intravenous amino acid infusion during general anaesthesiaprevents decreases in core temperature resulting from increasedenergy expenditure and heat accumulation. Methods. We investigated whether such stimulation also occursduring spinal anaesthesia, which blocks sympathetic nervousactivity. We examined the effect of i.v. amino acid infusionon changes in core temperature during spinal anaesthesia. Thirty-fivepatients were divided into two groups: an i.v. amino acid infusiongroup (4 kJ kg^–1 h^–1 starting 2 hbefore surgery); and a saline infusion group. Tympanic membranecore temperature, forearm–fingertip temperature gradient(an index of peripheral vasoconstriction) and mean skin temperaturewere measured for 90 min after the onset of spinal anaesthesia. Results. Changes in mean arterial pressure and heart rate didnot differ significantly between the groups during the studyperiod. Mean final core temperature 90 min after inductionof spinal anaesthesia was 35.8 (SEM 0.1)°C in the salinegroup and 36.6 (0.1)°C in the amino acid group (P<0.05).The increased level of oxygen consumption in the amino acidgroup compared with the saline group was preserved even afterthe onset of spinal anaesthesia. The thermal vasoconstrictionthreshold, defined as the tympanic membrane temperature thattriggered a rapid increase in forearm–fingertip temperaturegradient, was increased in the amino acid group [36.8 (0.1)°C]compared with the saline group [36.5 (0.1)°C] (P<0.05). Conclusions. Preoperative infusion of amino acids effectivelyprevents spinal anaesthesia-induced hypothermia by maintaininga higher metabolic rate and increasing the threshold core temperaturefor thermal vasoconstriction. Br J Anaesth 2003; 90: 58–61     

Unusually early onset of post-dural puncture headache after spinal anaesthesia using a 27G Whittacre needle

We present a case of a post-dural puncture headache occurring20 min after spinal anaesthesia using a 27-Gauge Whittacre needle.The unusually early occurrence of this complication is thoughtto be the first of its kind reported in the literature and highlightsthe novelty of this case.     

Effect of intravenous vasopressor on spread of spinal anaesthesia and fetal acid-base equilibrium

Background: We previously found rostral spread of spinal plain levobupivacaineto be less with prophylactic i.v. phenylephrine than with ephedrineduring Caesarean delivery. This study investigated whether rostralspread of spinal hyperbaric bupivacaine is also less with phenylephrinethan with ephedrine. Methods: The study was randomized and double blind. It compared phenylephrine100 µg ml^–1 (phenylephrine group, n = 27), and ephedrine4.5 mg ml^–1 (ephedrine group, n = 27), given by infusionduring spinal anaesthesia for Caesarean delivery. Block heightwas assessed to cold and light touch sensation at 15, 30, 60,and 90-min after the spinal injection of 2.8 ml of hyperbaric0.5% w/v bupivacaine, combined with 0.4 ml diamorphine (1 mgml^–1). Umbilical blood gas values were monitored duringthe study. Results: Block height was similar for both groups at all of the assessmenttimes. Umbilical artery pH was higher with phenylephrine [median7.32 (IQR 7.28–7.34)] than with ephedrine [7.20 (7.10–7.28)](P < 0.0001). There was a strong negative correlation betweenumbilical artery pH and spinal-delivery interval, but only withephedrine: phenylephrine group, r² = 0.09 (P = 0.17), and ephedrinegroup, r² = 0.53 (P < 0.0001). Five-minute Apgar scores werehigher with phenylephrine [10 (9–10)] than ephedrine [9(9–9)] (P = 0.009). Conclusions: In contrast to its effect on spinal plain levobupivacaine, wedid not find rostral spread of spinal hyperbaric bupivacaineto be less with prophylactic phenylephrine than with ephedrine.We observed an unexpectedly high incidence of fetal acidosiswith ephedrine and found evidence that longer spinal-deliveryintervals increase the risk of fetal acidosis developing withephedrine, but not phenylephrine.     

Coexisting harlequin and Horner syndromes after high thoracic paravertebral anaesthesia

A patient undergoing left mastectomy and immediate latissimusdorsi breast reconstruction under combined paravertebral blockand general anaesthesia developed transient, well-demarcated,right-sided hemifacial erythema and sweating, and left-sidedHorner syndrome postoperatively. This ‘harlequin’appearance occurs because of a normal or excessive vasodilatory,thermoregulatory response to heat or emotion mediated by anintact sympathetic pathway on the erythematous side, togetherwith relative pallor of the pharmacologically blocked side.     

Incremental spinal anaesthesia for elective Caesarean section in a patient with Eisenmenger's syndrome

We describe a new approach to anaesthesia for elective Caesareansection in a woman with Eisenmenger’s syndrome. Incrementalregional anaesthesia was performed using a microspinal catheterand haemodynamic monitoring included transthoracic bioimpedancecardiography. This approach allowed the disadvantages of generalanaesthesia and invasive cardiac output monitoring to be avoided. Br J Anaesth 2001; 86: 723–6     

Sedation caused by clonidine in patients with spinal cord injury

Background. In patients with spinal cord injury, cephalad spreadof intrathecal (i.t.) medication could be delayed. Methods. We used bispectral index and an observer scale to assesssedation after two different doses of i.t. clonidine in patientswith or without spinal cord injury. Twelve patients with neurologicaldeficit caused by trauma (Spinal Cord Injury, SCI) were comparedwith patients without neurological disease. They received 10mg of i.t. bupivacaine with clonidine, with either 50 µg(low dose, n=6) or 150 µg (high dose, n=6) at L₂–L₃.A further 12 patients, six with spinal trauma lesion and sixhealthy, received i.t. bupivacaine and 150 µg of i.m.clonidine. Results. Sedation and a decrease in BIS occurred only in patientsreceiving 150 µg of clonidine. Onset of sedation and thedecrease in BIS was delayed in most spinal cord injured patientswhatever the route of administration (P<0.001). Durationof sedation was not different between the groups. Delayed sedationand decrease of BIS after i.t. clonidine in patients with spinalcord injury are similar than those observed after i.m. clonidine. Conclusion. A systemic effect is likely to be the main reasonfor sedation. Br J Anaesth 2003; 90: 742–5     

Dural ectasia: a likely cause of inadequate spinal anaesthesia in two parturients with Marfan's syndrome

We report two cases of Caesarean section in patients with Marfan'ssyndrome where continuous subarachnoid anaesthesia failed toprovide an adequate surgical block. This was possibly becauseof dural ectasia, which was confirmed by a computed tomographyscan in both cases.     

Haemodynamic changes during high spinal anaesthesia in children having open heart surgery

BACKGROUND: This prospective series examined the haemodynamic effects of high spinal anaesthesia in combination with light general anaesthesia in infants and children undergoing open heart surgery who were candidates for immediate or early postoperative extubation. METHODS: After midazolam premedication and sevoflurane inhalation induction, 30 patients, aged 7 months to 13 years, who were undergoing open heart surgery, received spinal anaesthetics with 0.5% tetracaine D10 mixed with morphine. The spinal blocks were placed at the L2,3 or L3,4 interspace with cephalad spread being promoted by positioning the patient in 30 degrees of Trendelenburg for a minimum of 10 min. Maintenance of anaesthesia was with isoflurane 0.2-0.5% in 70% nitrous oxide to maintain heart rate and blood pressure within 20% of postinduction baseline values. Haemodynamic values were recorded at predetermined timed intervals and intraoperative events up to and including aortic cannulation. For analysis of the data, patients were divided into four age groups (< 1 years, 1-3 years, 4-6 years and > 7 years). RESULTS: Haemodynamic stability was demonstrated in all four age groups. Statistically significant slowing of the heart rate did occur in the groups older than 1 year at 25 min, although clinically significant bradycardia requiring treatment never occurred. Hypotension did occur during specific surgical manipulations but recovered spontaneously. Atropine, fluid boluses and vasopressors were never used. At the conclusion of surgery, all patients met extubation criteria and could move all four extremities. CONCLUSIONS: High spinal anaesthesia with hyperbaric tetracaine and morphine in combination with light general anaesthesia is well tolerated haemodynamically by the paediatric population studied.     

Development of a difficulty score for spinal anaesthesia

Background. Multiple attempts at spinal puncture may be hazardous.Accurate preoperative prediction of difficulty adds to the deliveryof high quality care. This clinical trial was designed to: (i)determine the predictive performance of difficulty variables;(ii) compare senior and junior anaesthetists; (iii) developa score to predict difficulty during the performance of spinalanaesthesia. Methods. A total of 300 patients subjected to urological proceduresand scheduled for spinal anaesthesia were independently assessedand stratified according to the categories of the difficultypredictors of spinal anaesthesia into one of nine grades (0–8)and randomized according to the experience of the anaesthetistinto two groups (group A, staff with more than 15 yrs’experience; group B, resident with more than 6 months but lessthan 1 yr in training). The number of attempts and levels, andsuccess rate of the technique were the outcome variables. Datawere analysed by multivariate analysis and receiver operatingcharacteristic (ROC) curves. Results. The bony landmarks of the back and the radiologicalcharacteristics of the lumbar vertebrae were two independentpredictors of difficulty. Multivariate analysis indicated differencesbetween junior and senior staff but ROC curves indicated nodifference. Grade 4 was the difficulty score at or above whichdifficulty was expected whether or not radiological characteristicsof the vertebrae were included. Conclusions. Spinal bony landmarks and radiological characteristicsof the lumbar vertebrae are independent predictors of difficultyduring spinal anaesthesia. There is no difference between seniorand junior anaesthetists. Grade 4 is the difficulty score ator above which difficulty is expected. Br J Anaesth 2004; 92: 354–60     

Paediatric regional anaesthesia,a survey of practice in the United Kingdom

Background. A variety of techniques and drugs, many unlicensed,is used in paediatric regional anaesthesia. This study is thefirst to survey paediatric anaesthetists about the techniquesand drugs used in paediatric regional anaesthesia. The aim isto provide a record and benchmark of UK practice. Methods. A postal questionnaire was sent to all members of theAssociation of Paediatric Anaesthetists residing in the UK.Information was requested on the type of hospital worked in,years of practice, paediatric anaesthesia workload, regionalanaesthesia techniques used, and drugs used in regional anaesthesia. Results. A total of 220 responses from 264 questionnaires (83.3%)were received. Of these respondents, 155 (70%) practised paediatricanaesthesia as more than 50% of their workload, and 10 had retiredor returned blank forms. Two hundred and two of 210 (96%) usecaudal anaesthesia and 151 (72%) use caudal, epidural and peripheralblock. One hundred and ninety-two of 210 (91%) have no lowerage limit for using caudal anaesthesia. One hundred and twenty-threeof 210 anaesthetists (58%) used adjuvants with local anaestheticsin caudal block, the most common being fentanyl [44/210 (21%)],clonidine [55/210 (26%)], diamorphine [27/210 (13%)] and ketamine[67/210 (32%)]. Those working in specialist centres or teachinghospitals or who had a greater paediatric anaesthesia workloadwere more likely to use a greater variety of regional anaesthesiatechniques. Conclusions. Caudal anaesthesia is widely used for patientsof all ages by almost all practitioners. Most anaesthetistsat all hospital types and experience levels use adjuvants withlocal anaesthetics when performing caudal anaesthesia. Thosewith more experience in paediatric anaesthesia and those inspecialist centres commonly use other neuraxial and peripheralblock techniques. Br J Anaesth 2002; 89: 707–10     

Comparison of hyperbaric and plain ropivacaine 15 mg in spinal anaesthesia for lower limb surgery

Background. Previously, plain ropivacaine 15 mg given intrathecallyhas been shown to be feasible for ambulatory surgery of lower-extremities.Hypothetically, hyperbaric solution could improve and shortenthe block. Methods. This prospective, randomized, double-blind study included56 patients undergoing surgery of lower extremities. They receivedintrathecally either 1.5 ml of ropivacaine 10 mg ml^–1and 0.5 ml of glucose 300 mg ml^–1 (HYP) or 2 ml of ropivacaine7.5 mg ml^–1 (PL). Results. All patients in Group HYP achieved T₁₀ dermatome analgesiabut only 64% (18/28) of Group PL. T₁₀ analgesia was reachedin 5 min (median, range 5–20 min) in the HYP group vs10 min (5–45 min) in the PL group (P=0.022), and fullmotor block in 10 min (5–45 min) vs 20 min (5–60min) (P=0.003), respectively. Group HYP had a longer durationof analgesia at T₁₀; 83 min (5–145 min) vs 33 min (0–140min) (P=0.004). Duration of sensory block from injection ofthe anesthetic to complete recovery was shorter in Group HYPthan in Group PL, 210 min (120–270 min) vs 270 min (210–360min) (P<0.001), as was duration of motor block, 120 min (5–150min) vs 210 min (120–330 min) (P<0.001). Patients ofGroup HYP attained discharge criteria earlier than those ofGroup PL (P=0.009). Conclusion. In comparison with the plain solution, 15 mg ofintrathecal hyperbaric ropivacaine produced a faster onset,greater success rate of analgesia at the level of T₁₀ dermatome,and faster recovery of the block.