Assessment of preoperative fluid depletion using bioimpedance analysis

Background. Fluid depletion during the perioperative periodis associated with poorer outcome. Non-invasive measurementof total body water by bioimpedance may enable preoperativefluid depletion and its influence on perioperative outcome tobe assessed. Methods. Weight and foot bioimpedance were recorded under standardizedconditions in patients undergoing bowel preparation (n=43) orday surgery (n=44). Fifteen volunteers also followed standardnil-by-mouth instructions on two separate occasions to assessthe variabilities of weight and bioimpedance over time. Results. Body weight fell by 1.27 kg (95% CI 1.03–1.50kg; P<0.0001) and foot bioimpedance increased by 51 ohm afterbowel preparation (95% CI 36–66; P<0.0001). Weightchange after the nil-by-mouth period in day-surgery patients(mean –0.22 kg, 95% CI –0.05 to –0.47 kg;P=0.07) correlated (r=–0.46; P=0.005) with an increasein bioimpedance (16 ohms, 95% CI 5–27 ohms; P=0.01). Nodifference between two separate bioimpedance measurements wasseen in the volunteer group. Conclusions. Further work is warranted to determine if bioimpedancechanges may serve as a useful indicator of perioperative fluiddepletion. Br J Anaesth 2004; 92: 134–6     

Prevalence of postoperative bladder distension and urinary retention detected by ultrasound measurement

Background. Postoperative bladder distension and urinary retentionare commonly underestimated. Ultrasound enables accurate measurementof bladder volume and thus makes it possible to determine theprevalence of postoperative bladder distension. Methods. Using ultrasound, we measured the volume of the bladdercontents at the time of discharge from the recovery room in177 adult patients who had undergone thoracic, vascular, abdominal,orthopaedic or ENT surgery. Results. Forty-four per cent of the patients had a bladder volume>500 ml and 54% of the 44%, who had no symptoms of bladderdistension, were unable to void spontaneously within 30 min.The risk factors for urinary retention were age >60 yr (oddsratio (OR) 2.11, 95% confidence interval (CI) 1.01–4.38),spinal anaesthesia (OR 3.97, 95% CI 1.32–11.89) and durationof surgery >120 min (OR 3.03, 95% CI 1.39–6.61). Conclusion. Before discharge from the recovery room it seemsworthwhile to systematically check the bladder volume with aportable ultrasound device in patients with risk factors. Br J Anaesth 2004; 92: 544–6     

Predictive perioperative factors for developing severe sepsis after major surgery

Background. Early identification of high-risk patients undergoingmajor surgery can result in an aggressive management affectingthe outcome. Methods. We designed a prospective cohort study of 93 adultpatients undergoing major oncological surgery to identify thepredictive risk factors for developing postoperative severesepsis. Results. Nineteen of 93 patients developed a severe sepsis aftersurgery; seven of the septic patients died in intensive careunit. Multivariate analysis discriminated preoperative and postoperative(first and second day after surgery) predictive risk factors.The postoperative severe sepsis was independently associatedwith preoperative factors like male gender (OR 4.7, 95% CI between1.5 and 15.5, P<0.01) and Charlson co-morbidity index (OR1.3, 95% CI between 1.07 and 1.6, P<0.01). After the surgery,the presence of systemic inflammatory response syndrome (OR4.0, 95% CI between 1.02 and 15.7, P<0.05) and a logisticorgan dysfunction score on day 2 (OR 3.3, 95% CI between 1.9and 5.7, P<0.001) were found as independent predictive factors. Conclusion. We have shown that some of the markers that canbe easily collected in the preoperative or postoperative visitscan be used to screen the patients at high risk for developingsevere sepsis after major surgery.     

Nitrous oxide does not change the incidence of postoperative delirium or cognitive decline in elderly surgical patients

Background. Postoperative delirium and cognitive decline arecommon in elderly surgical patients after non-cardiac surgery.Despite this prevalence and clinical importance, no specificaetiological factor has been identified for postoperative deliriumand cognitive decline. In experimental setting in a rat model,nitrous oxide (N₂O) produces neurotoxic effect at high concentrationsand in an age-dependent manner. Whether this neurotoxic responsemay be observed clinically has not been previously determined.We hypothesized that in the elderly patients undergoing non-cardiacsurgery, exposure to N₂O resulted in an increased incidenceof postoperative delirium than would be expected for patientsnot receiving N₂O. Methods. Patients who were 65 yr of age, undergoing non-cardiacsurgery and requiring general anaesthesia were randomized toreceive an inhalational agent and either N₂O with oxygen oroxygen alone. A structured interview was conducted before operationand for the first two postoperative days to determine the presenceof delirium using the Confusion Assessment Method. Results. A total of 228 patients were studied with a mean (range)age of 73.9 (65–95) yr. After operation, 43.8% of patientsdeveloped delirium. By multivariate logistic regression, age[odds ratio (OR) 1.07; 95% confidence interval (CI) 1.02–1.26],dependence on performing one or more independent activitiesof daily living (OR 1.54; 95% CI 1.01–2.35), use of patient-controlledanalgesia for postoperative pain control (OR 3.75; 95% CI 1.27–11.01)and postoperative use of benzodiazepine (OR 2.29; 95% CI 1.21–4.36)were independently associated with an increased risk for postoperativedelirium. In contrast, the use of N₂O had no association withpostoperative delirium. Conclusions. Exposure to N₂O resulted in an equal incidenceof postoperative delirium when compared with no exposure toN₂O. ⁴Present address: Staff Statistician, University of Pittsburgh,PA 15213, USA     

Effects of sustained post-traumatic shock and initial fluid resuscitation on extravascular lung water content and pulmonary vascular pressures in a porcine model of shock

Background. The temporal evolution of lung injury followingpost-traumatic shock is poorly understood. In the present studywe have tested the hypothesis that manifestations of pulmonaryvascular dysfunction may be demonstrable within the first hourafter the onset of shock. Methods. Twenty-nine anaesthetized pigs (mean weight 27.4 kg;(SD) 3.2) were randomly allocated to three groups: control (C,n=9), shock resuscitated with either NaCl 0.9% (S, n=10), or4% gelatine (G, n=10). Shock was maintained for 1 h followedby fluid resuscitation with either normal saline or 4% gelatinesolution. Cardiac output (CO), mean arterial pressure (MAP),mixed venous saturation (Sv_O2), blood lactate concentration,mean pulmonary artery pressure (MPAP), MPAP/MAP, pulmonary vascularresistance (PVR), extravascular lung water index (EVLWi), Pa_O2/FI_O2,venous admixture (Q^·_S/Q^·_T), and dynamic lung compliance(C_dyn) were measured at baseline, beginning of shock phase,end of shock phase, and post-resuscitation. Results. At the end of volume resuscitation CO was restoredto control values in both shock groups. MAP remained significantlybelow control values (95% CI: C=70–95, S=28–52,G=45–69 mm Hg) in both shock groups. MPAP/MAP was significantlygreater in both shock groups at the end of the shock phase (95%CI; C=0.15–0.24, S=0.28–0.38, G=0.32–0.42)and at the post-resuscitation phase (95% CI: C=0.12–0.30,S=0.43–0.61, G=0.32–0.49) indicating the presenceof relative pulmonary hypertension. This was associated witha significant increase in PVR in Group S (F=3.9; P<0.05).There were no significant changes in Pa_O2/FI_O2, Q^·_S/Q^·_T,EVLWi, or C_dyn. In a small cohort of animals a measurable increasein EVLWi (>30%) and reduction in C_dyn (>10%) were observed. Conclusions. Pulmonary vascular injury manifesting as relativepulmonary hypertension and increased PVR may occur within thefirst hour after the onset of shock. These changes may not beaccompanied by overt changes in oxygenation, compliance, orEVLWi. Br J Anaesth 2003; 91: 224–32     

Platelet function point-of-care tests in post-bypass cardiac surgery: are they relevant?

Background. Platelet dysfunction is an important cause of excessivebleeding after cardiac surgery. We assessed two platelet functionpoint-of-care tests: the platelet function analyser (PFA-100)and the Hemostatus^TM in patients with and without excessivebleeding after cardiac surgery with cardiopulmonary bypass. Methods. Mediastinal chest tube drainage (MCTD) was measuredfor the first 6 h in the intensive care unit (ICU). Haematologyand coagulation tests were done on arrival in the ICU, and whenexcessive bleeding occurred (MCTD >1 ml kg^–1 h^–1)or after 3 h. Results. Eighteen patients bled excessively and 27 had normalMCTD. Hemostatus measurements were prolonged in those with excessivebleeding compared with the normal group. The times for PFA-100adenosine diphosphate (ADP) and epinephrine were 91 vs 71 s(P=0.004) and 155 vs 114 s (P=0.02) in the bleeding and normalgroup s, respectively. None of the Hemostatus or PFA-100 valuescorrelated with total MCTD. Depending on the agonist used, maximumaggregation was 33–81% and 52–86% in bleeding andnormal groups, respectively. Only poor correlations were foundbetween PFA-100 epinephrine and maximum aggregation in responseto ADP (r=–0.52, P=0.03) or to collagen (r=–0.48,P=0.04). Conclusion. Patients bleeding excessively in the ICU had abnormalmeasurements in point-of-care tests without a dramatic decreasein aggregation. Except for patients with increased risk of postbypassbleeding, point-of-care tests are not useful for routine useafter cardiac surgery. Br J Anaesth 2002; 89: 715–21     

Effects of halothane, sevoflurane and propofol on left ventricular diastolic function in humans during spontaneous and mechanical ventilation

Background. There is limited knowledge of the effects of anaestheticson left ventricular (LV) diastolic function in humans. Our aimwas to evaluate these effects in humans free from cardiovasculardisease. Methods. Sixty patients (aged 18–47 yr) who had no historyor signs of cardiovascular disease were randomized to receivegeneral anaesthesia with halothane, sevoflurane or propofol.Echocardiography was performed at baseline and during spontaneousrespiration at 1 minimum alveolar concentration (MAC) of theinhalational agents or propofol 4 µg ml^–1 (step1), and repeated during positive-pressure ventilation with 1and 1.5 MAC of the inhalational agents or with propofol 4 and6 µg ml^–1 (steps 2A and 2B). Analysis of echocardiographicmeasurements focused on heart rate corrected isovolumic relaxationtime (IVRT_c) and early diastolic peak velocity of the lateralmitral annulus (E_a). Results. IVRT_c decreased from baseline to step 1 in the halothanegroup (82 [95% CI, 76–88] ms and 74 [95% CI, 68–80]ms respectively; P=0.02), remained stable in the sevofluranegroup (78 [95% CI, 72–83] ms and 73 [95% CI, 67–81]ms; n.s.) and increased in the propofol group (80 [95% CI, 74–86]ms and 92 [95% CI, 84–102] ms; P=0.02). E_a decreased inthe propofol group only (18.8 [95% CI, 16.5–19.9] cm s^–1and 16.0 [95% CI, 14.9–17.9] cm s^–1; P=0.003). Fromstep 2A to step 2B, IVRT_c increased further in the propofolgroup (109 [95% CI, 99–121] ms and 119 [95% CI, 99–135]ms; P=0.04) but remained stable in the other two groups. E_adid not change from step 2A to step 2B. Conclusions. Halothane and sevoflurane did not impair LV relaxation,whereas propofol caused a mild impairment. However, the impairmentby propofol was of a magnitude that is unlikely to cause clinicaldiastolic dysfunction.      

Propofol 1% versus propofol 2% in children undergoing minor ENT surgery

Background. The induction characteristics of propofol 1% and2% were compared in children undergoing ENT surgery, in a prospective,randomized, double-blind study. Methods. One hundred and eight children received propofol 1%(n=55) or 2% (n=53) for induction and maintenance of anaesthesia.For induction, propofol 4 mg kg^–1 was injectedat a constant rate (1200 ml h^–1), supplementedwith alfentanil. Intubating conditions without the use of aneuromuscular blocking agent were scored. Results. Pain on injection occurred in 9% and 21% of patientsafter propofol 1% and 2%, respectively (P=0.09). Loss of consciousnesswas more rapid with propofol 2% compared with propofol 1% (47 svs 54 s; P=0.02). Spontaneous movements during inductionoccurred in 22% and 34% (P=0.18), and intubating conditionswere satisfactory in 87% and 96% (P=0.19) of children receivingpropofol 1% or 2%, respectively. There were no differences betweenthe two groups in respect of haemodynamic changes or adverseevents. Conclusions. For the end-points tested, propofol 1% and propofol2% are similar for induction of anaesthesia in children undergoingminor ENT surgery. Br J Anaesth 2003: 90: 375–7     

Perianaesthetic risks and outcomes of abdominal surgery for metastatic carcinoid tumours

Patients with metastatic carcinoid tumours often undergo surgicalprocedures to reduce the tumour burden and associated debilitatingsymptoms. These procedures and anaesthesia can precipitate alife-threatening carcinoid crisis. To assess perioperative outcomes,we studied retrospectively the medical records of adult patientsfrom 1983 to 1996 who underwent abdominal surgery for metastaticcarcinoid tumours. Preoperative risk factors, intraoperativecomplications and complications occurring in the 30 daysafter surgery were recorded. Perioperative complications ordeath occurred in 15 of 119 patients (12.6%, exact confidenceinterval 7.2–19.9). None of the 45 patients who receivedoctreotide intraoperatively experienced intraoperative complicationscompared with eight of the 73 patients (11.0%) who did not receiveoctreotide (P=0.023). The presence of carcinoid heart diseaseand high urinary output of 5-hydroxyindoleacetic acid preoperativelywere statistically significant risk factors for perioperativecomplications. Br J Anaesth 2001; 87: 447–52     

Prospective randomized controlled trial of acute normovolaemic haemodilution in major gastrointestinal surgery

Background. The efficacy of acute normovolaemic haemodilution(ANH) remains uncertain because of a lack of well-designed prospectiverandomized controlled trials. The aim of this study was to assessthe effects of ANH on allogeneic transfusion, postoperativecomplications, and duration of stay. Methods. Consecutive patients undergoing major gastrointestinalsurgery were randomized to a planned 3-unit ANH, or no ANH.Both groups underwent identical management including adherenceto a transfusion protocol after surgery. Outcome measures includedthe number of patients receiving allogeneic blood, complications,and duration of stay. Results. 380 patients were screened of which 160 were includedin the study, median age was 62 yr (range 23–90), ‘ANH’n=78, ‘no ANH’ n=82. There was no significant differencebetween groups in the number of patients receiving allogeneicblood 22/78 (28%) vs 25/82 (30%), the total number of allogeneicunits transfused (90 vs 93), complication rate, or durationof stay. Haemodilution significantly increased anaesthetic time,median 55 (range 15–90) vs 40 min (range 17–80)(P<0.001). Significantly fewer patients in the ANH groupexperienced oliguria in the immediate postoperative period 37/78(47%) vs 55/82 (67%) (P=0.012). The most significant factorsaffecting transfusion were blood loss, starting haemoglobin,and age. When compared with ASA-matched historical controls,the introduction of a transfusion protocol reduced the transfusionrate in colorectal patients from 136/333 (41%) to 37/138 (27%),P=0.004. Conclusions. In this large pragmatic study, ANH did not affectallogeneic transfusion rate in major gastrointestinal surgery.Preoperative haemoglobin, blood loss, and transfusion protocolare the key factors influencing allogeneic transfusion.     

Effects of hydroxyethyl starch administration on renal function in critically ill patients

BACKGROUND: The influence of hydroxyethyl starch (HES) solutions on renalfunction is controversial. We investigated the effect of HESadministration on renal function in critically ill patientsenrolled in a large multicentre observational European study. METHODS: All adult patients admitted to the 198 participating intensivecare units (ICUs) during a 15-day period were enrolled. Prospectivelycollected data included daily fluid administration, urine output,sequential organ failure assessment (SOFA) score, serum creatininelevels, and the need for renal replacement therapy (RRT) duringthe ICU stay. RESULTS: Of 3147 patients, 1075 (34%) received HES. Patients who receivedHES were older [mean (SD): 62 (SD 17) vs 60 (18) years,P = 0.022], more likely to be surgical admissions, had a higherincidence of haematological malignancy and heart failure, higherSAPS II [40.0 (17.0) vs 34.7 (16.9), P < 0.001] and SOFA[6.2 (3.7) vs 5.0 (3.9), P < 0.001] scores, and less likelyto be receiving RRT (2 vs 4%, P < 0.001) than those who didnot receive HES. The renal SOFA score increased significantlyover the ICU stay independent of the type of fluid administered.Although more patients who received HES needed RRT than non-HESpatients (11 vs 9%, P = 0.006), HES administration was not associatedwith an increased risk for subsequent RRT in a multivariableanalysis [odds ratio (OR): 0.417, 95% confidence interval (CI):0.05–3.27, P = 0.406]. Sepsis (OR: 2.03, 95% CI: 1.37–3.02,P < 0.001), cardiovascular failure (OR: 6.88, 95% CI: 4.49–10.56,P < 0.001), haematological cancer (OR: 2.83, 95% CI: 1.28–6.25,P = 0.01), and baseline renal SOFA scores > 1 (P < 0.01for renal SOFA 2, 3, and 4 with renal SOFA = 0 as a reference)were all associated with a higher need for RRT. CONCLUSIONS: In this observational study, haematological cancer, the presenceof sepsis, cardiovascular failure, and baseline renal functionas assessed by the SOFA score were independent risk factorsfor the subsequent need for RRT in the ICU. The administrationof HES had no influence on renal function or the need for RRTin the ICU.     

Cost-effectiveness of three combinations of antiemetics in the prevention of postoperative nausea and vomiting

Background. This study compares the cost-effectiveness of threecombinations of antiemetics in the prevention of postoperativenausea and vomiting (PONV). Methods. We conducted a prospective, double-blind study. NinetyASA I–II females, 18–65 yr, undergoing general anaesthesiafor major gynaecological surgery, with standardized postoperativeanalgesia (intrathecal 0.2 mg plus i.v. PCA morphine), wererandomly assigned to receive: ondansetron 4 mg plus droperidol1.25 mg after induction and droperidol 1.25 mg 12 h later (Group1); dexamethasone 8 mg plus droperidol 1.25 mg after inductionand droperidol 1.25 mg 12 h later (Group 2); ondansetron 4 mgplus dexamethasone 8 mg after induction and placebo 12 h later(Group 3). A decision analysis tree was used to divide eachgroup into nine mutually exclusive subgroups, depending on theincidence of PONV, need for rescue therapy, side effects andtheir treatment. Direct cost and probabilities were calculatedfor each subgroup, then a cost-effectiveness analysis was conductedfrom the hospital point of view. Results. Groups 1 and 3 were more effective (80 and 70%) thanGroup 2 (40%, P=0.004) in preventing PONV but also more expensive.Compared with Group 2, the incremental cost per extra patientwithout PONV was €6.99 (95% CI, –1.26 to 36.57) forGroup 1 and €13.55 (95% CI, 0.89–132.90) for Group3. Conclusion. Ondansetron+droperidol is cheaper and at least aseffective as ondansetron+ dexamethasone, and it is more effectivethan dexamethasone+droperidol with a reasonable extra cost. Br J Anaesth 2003; 91: 589–92     

Utility of B-type natriuretic peptide in predicting perioperative cardiac events in patients undergoing major non-cardiac surgery

Background: B-type natriuretic peptide (BNP) levels predict cardiovascularrisk in several settings. We hypothesized that they would identifyindividuals at increased risk of early cardiac complicationsafter major non-cardiac surgery. The current study tests thishypothesis. Methods: Two hundred and four patients undergoing major non-cardiac surgerywere studied. The primary end-point was the development of acutemyocardial injury [defined as cardiac troponin I (cTnI) level> 0.32 ng ml^–1] or death in the 3 days after surgery. Results: Preoperative BNP levels were raised in patients who died orsuffered perioperative myocardial injury (median 52.2 vs 22.2pg ml^–1, P = 0.01) and BNP predicted this outcome withan area under the receiver operating characteristic curve of0.72 [95% confidence interval (CI) 0.59–0.86, P = 0.01].A preoperative BNP value > 40 pg ml^–1 was associatedwith an increased risk of death or perioperative myocardialinjury [odds ratio (OR) 6.8, 95% CI 1.8–25.9, P = 0.003],and remained independently predictive after correction for theRevised Cardiac Risk Index. Preoperative BNP levels were higherin patients who exhibited new onset atrial fibrillation or ST/T-wavechanges on their postoperative ECG (median 50.5 vs 22.5 pg litre^–1,P = 0.01). They were also higher in patients who had eitherelevation of cTnI > 0.32 ng ml^–1 or postoperative ECGabnormalities (median 50.4 vs 21.5 pg ml^–1, P < 0.001). Conclusions: In the setting of major non-cardiac surgery, preoperative BNPlevels are higher in patients who experience perioperative deathand myocardial injury. Larger studies are required to confirmthese data and to clarify what BNP levels may add to existingmethods of risk stratification.     

Increased carbon dioxide absorption during retroperitoneal laparoscopy

Background. Retroperitoneoscopy for renal surgery is now a commonprocedure. We compared carbon dioxide absorption in patientsundergoing retroperitoneoscopy for adrenal or renal surgerywith that of patients undergoing laparoscopic cholecystectomy. Methods. We measured carbon dioxide elimination with a metabolicmonitor in 30 anaesthetized patients with controlled ventilation,undergoing retroperitoneoscopy (n=10), laparoscopy (n=10) ororthopaedic surgery (n=10). Results. Carbon dioxide production increased by 38, 46 and 63%at 30, 60 and 90 min after insufflation (P<0.01) in patientshaving retroperitoneoscopy. Carbon dioxide production (mean(SD)) increased from 92 (21) to 150 (43) ml min^–1 m^–260–90 min after insufflation and remained increased afterthe end of insufflation. During laparoscopy, V^·_CO2 increasedless (by 15%) (P<0.05 compared with retroperitoneoscopy)and remained steady throughout the procedure. Conclusion. Retroperitoneal carbon dioxide insufflation causesmore carbon dioxide absorption than intraperitoneal insufflation,and controlled ventilation should be increased if hypercapniashould be avoided. Br J Anaesth 2003; 91: 793–6     

Epidural test dose with levobupivacaine and ropivacaine: determination of ED(50) motor block after spinal administration

Background. When a test is required to detect a possible intrathecalcatheter, many would seek to use the same local anaestheticas that used for epidural analgesia. The rapid onset of inappropriatemotor block after a local anaesthetic administered epidurallyimplies intrathecal spread. Because of claims of greater sensory–motorseparation, or because of reduced potency compared with bupivacaine,the efficacy of the new local anaesthetics in intrathecal testinghas been questioned. The aim of this study was to establishthe feasibility of a test dose for an inadvertent intrathecalcatheter using ropivacaine and levobupivacaine, and to establishthe dose required. Methods. Sixty women undergoing elective Caesarean section witha combined spinal– epidural technique were enrolled intothis prospective, double-blind sequential allocation study.The women were randomized to receive plain levobupivacaine 0.5%or ropivacaine 0.5% intrathecally. The dose was determined accordingto up–down sequential allocation. The end-point was anyevidence of lower limb motor block within 5 min of injection. Results. The ED₅₀ motor block at 5 min was 4.8 mg (95% CI, 4.49,5.28) for levobupivacaine and 5.9 mg (95% CI, 4.82, 6.98) forropivacaine (95% CI difference, 0.052, 1.98) (P=0.04). The estimatedED₉₅ motor block was 5.9 mg (95% CI 5.19, 6.71) for levobupivacaineand 8.3 mg (95% CI, 6.30, 10.44) for ropivacaine. The potencyratio between the two drugs was 0.83 (95% CI, 0.69, 0.99). Conclusions. Both local anaesthetics produce evidence of motorblock within 5 min of intrathecal injection and could serveas tests of intrathecal administration. Derived ED₉₅ valuessuggest 10 mg doses should be effective, but this study didnot measure predictive value. Ropivacaine is less potent formotor block than levobupivacaine by a factor of 0.83 (P<0.04). Br J Anaesth 2004; 92: 850–3     

Analgesia with sevoflurane during labour: ii. Sevoflurane compared with Entonox for labour analgesia

Background. We determined the optimal inspired sevoflurane concentrationfor use during labour as 0.8% in our previous study. This studycompared sevoflurane at a concentration of 0.8% and Entonox^®(nitrous oxide 50%: oxygen 50%) for analgesia during labourin 32 healthy parturients. Methods. Each mother underwent two open-label, three-part sequencesin random order, Entonox-sevoflurane-Entonox or sevoflurane-Entonox-sevoflurane.In each part the agent was self-administered during 10 contractions.A 100 mm visual analogue scores for pain relief and sedationwas completed immediately after each contraction. Results. Two patients withdrew during administration of sevoflurane(because of its odour) and five during Entonox (requesting epiduralanalgesia). Of the remaining women, data were available foranalysis from 29 participants: median (IQR [range]) pain reliefscores were significantly higher for sevoflurane 67 (55–74[33–100]) mm than for Entonox 51 (40–69.5 [13–100])mm (P<0.037). Nausea and vomiting were more common in theEntonox group [relative risk 2.7 (95% CI 1.3–5.7); P=0.004].No other adverse effects were observed in the mothers or babies.There was significantly more sedation with sevoflurane thanwith Entonox {74 (66.5–81 [32.5–100]) and 51 (41–69.5[13–100]) mm, respectively; P<0.001}. Twenty-nine patientspreferred sevoflurane to Entonox and found its sedative effectshelpful. Conclusions. We conclude that self-administered sevofluraneat subanaesthetic concentration (0.8%) can provide useful painrelief during the first stage of labour, and to a greater extentthan Entonox. Although greater sedative effects were experiencedwith sevoflurane, it was preferred to Entonox.      

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.     

Comparison of ropivacaine 0.5% (in glucose 5%) with bupivacaine 0.5% (in glucose 8%) for spinal anaesthesia for elective surgery

Background. Hyperbaric solutions of ropivacaine have been usedsuccessfully to provide spinal anaesthesia. This study was designedto compare the clinical efficacy of hyperbaric ropivacaine withthat of the commercially available hyperbaric preparation ofbupivacaine. Methods. Forty ASA grade I–II patients undergoing lower-abdominal,perineal or lower-limb surgery under spinal anaesthesia wererecruited and randomized to receive ropivacaine 5 mg ml^–1(with glucose 50 mg ml^–1), 3 ml or bupivacaine 5 mg ml^–1(with glucose 80 mg ml^–1), 3 ml. The level and durationof sensory block, intensity and duration of motor block, andtime to mobilize and micturate were recorded. Patients wereinterviewed at 24 h and at 1 week to identify any residual problems. Results. All blocks were adequate for the proposed surgery,but there were significant differences between the two groupsin mean time to onset of sensory block at T10 (ropivacaine 5min; bupivacaine 2 min; P<0.005), median maximum extent (ropivacaineT7; bupivacaine T5; P<0.005) and mean duration of sensoryblock at T10 (ropivacaine 56.5 min; bupivacaine 118 min; P=0.001).Patients receiving ropivacaine mobilized sooner (ropivacainemean 253.5 min; bupivacaine 331 min; P=0.002) and passed urinesooner (ropivacaine mean 276 min; bupivacaine 340.5 min; P=0.01)than those receiving bupivacaine. More patients in the bupivacainegroup required treatment for hypotension (>30% decrease insystolic pressure; P=0.001). Conclusions. Ropivacaine 15 mg in glucose 50 mg ml^–1 providesreliable spinal anaesthesia of shorter duration and with lesshypotension than bupivacaine. The recovery profile for ropivacainemay be of interest given that more surgery is being performedin the day-case setting. Br J Anaesth 2003; 90: 304–8     

Optimizing fluid therapy in mechanically ventilated patients after cardiac surgery by on-line monitoring of left ventricular stroke volume variations. Comparison with aortic systolic pressure variations

Background. Mechanical ventilation causes changes in left ventricularpreload leading to distinct variations in left ventricular strokevolume and systolic arterial pressure. Retrospective off-linequantification of systolic arterial pressure variations (SPV)has been validated as a sensitive method of predicting leftventricular response to volume administration. We report thereal-time measurement of left ventricular stroke volume variations(SVV) by continuous arterial pulse contour analysis and compareit with off-line measurements of SPV in patients after cardiacsurgery. Methods. SVV and SPV were determined before and after volumeloading with colloids in 20 mechanically ventilated patients. Results. SVV and SPV decreased significantly after volume loadingand were correlated (r=0.89; P<0.001). Changes in SVV andchanges in SPV as a result of volume loading were also significantlycorrelated (r=0.85; P<0.005). Changes in SVV correlated significantlywith changes in stroke volume index (SVI) (r=0.67; P<0.005)as did changes in SPV (r=0.56; P<0.05). SVV determined beforevolume loading correlated significantly with changes in SVI(R=0.67; P <0.005). Using receiver operating characteristicscurves, the area under the curve was statistically greater forSVV (0.824; 95% confidence interval: [CI] 0.64–1.0) andSPV (0.81; CI: 0.62–1.0) than for central venous pressure(0.451; CI: 0.17–0.74). Conclusions. Monitoring of SVV enables real-time predictionand monitoring of the left ventricular response to preload enhancementin patients after cardiac surgery and is helpful for guidingvolume therapy. Br J Anaesth 2002; 88: 124–6     

Sedation during spinal anaesthesia in infants

Background. Neuraxial anaesthesia in adults decreases the doseof i.v. or inhalational anaesthetic needed to reach a desiredlevel of sedation. Furthermore, spinal anaesthesia alone hasa sedative effect. The mechanism behind this phenomenon is presumedto be decreased afferent stimulation of the reticular activatingsystem after sympatholysis. We hypothesized that this mechanismis equally active in infants undergoing spinal anaesthesia. Methods. In total, 20 unpremedicated former preterm infantsunderwent surgery under spinal anaesthesia with hyperbaric bupivacaine0.5% 1 mg kg^–1 with epinephrine 10 µg kg^–1.No additional sedatives or anaesthetics were administered. Sedationwas evaluated using the bispectral index (BIS) score and the95% spectral edge frequency (SEF₉₅). Results. After spinal anaesthesia, mean (SD) BIS began to decreasesignificantly from baseline 97.0 (1.1) to 83.9 (14.4) after15 min (P=0.006). BIS decreased further, reaching the lowestvalues after 30 min [62.2 (14.0); P<0.00001]. Mean (SD) SEF₉₅declined from baseline 26.1 (1.8) Hz to 24.3 (3.1) after 5 min(P=0.02) and further to 9.9 (3.8) after 30 min (P<0.00001).Mean arterial pressure also decreased significantly from 66.5(4.7) mm Hg within 10 min to 56.1 (5.6) after spinal anaesthesia(P=0.0002), while heart rate remained stable. Conclusions. These results suggest that sedation after spinalanaesthesia in infants is at least as pronounced as in adults.The sedative effect of spinal anaesthesia should be kept inmind when additional sedatives are administered, especiallyin former preterm infants.