Canadian Journal of Anesthesia/Journal canadien d anesthésie

Licker, Marc; Schweizer, Alexandre; Höhn, Laurent; Morel, Denis R.

doi: 10.1007/bf03013949pmid: 10442956

PurposeTreatment with angiotensin-converting enzyme (ACE) inhibitors affects the autoregulation of renal blood flow and glomerular filtration and provides renal protective effects. The purpose of this case-control study was to investigate the effects of chronic ACE inhibition on perioperative renal hemodynamics and function.MethodWe prospectively studied renal function in two groups of patients, chronically treated or not, with ACE inhibitors (ACEI and control; n = 16, in each group) who underwent elective cardiac surgery under hypothermic cardiopulmonary bypass. Glomerular filtration rate, effective renal plasma flow, osmolar clearance and fractional excretion of sodium and potassium were determined before, during and after CPB. Additional measurements included plasma atrial natriuretic factor (ANF) as well as plasma and urinary cyclic GMP (cGMP), thromboxane B2 (T× B2) and 6-keto-PGF1.ResultsRenal functional and hemodynamic variables did not differ between the two groups, at any period. Cardiopulmonary bypass induced increases in urinary flow, osmolar clearance and fractional excretion of sodium and potassium in both groups. Plasma and urinary ratio of 6-keto-PGF1O T× B2 increased markedly and reflected a prédominent systemic and renal release of vasodilatory prostaglandins. Intraoperatively, ANF was higher in ACEIs than in control patients.ConclusionsLong term treatment with ACE inhibitors does not influence the perioperative changes in renal hemodynamics and function. During cardiopulmonary bypass, a transient impairment in solute reabsorption is associated with renal release of vasodilatory mediators (nitric oxide and prostacyclin).

Self, Dalton D.; Bryson, Gregory L.; Sullivan, Patrick J.

doi: 10.1007/bf03013950pmid: 10442957

PurposeTo identify risk factors for post-carotid endarterectomy (CEA) hematoma formation and establish the incidence of this complication at The Ottawa Hospital — Civic Campus (TOH-CC).MethodsA chart review of all patients who underwent CEA at TOH-CC from January 1, 1996 to December 31,1997 was completed. Identified cases of post-CEA wound hematoma were entered into a case-control study using age and sex-matched controls from within the cohort. These matched pairs were assessed for 31 potential risk factors including demographic details, co-existing medical conditions, preoperative medications, intraoperative management, and postoperative parameters. Risk factors associated with post-CEA hematoma withP < 0.05 were entered into a backward step-wise logistic regression model for multivariate analysis.ResultsCharts from 249 patients were reviewed and 29 cases of post-carotid endarterectomy hematoma were identified (12% incidence). Six of the initial 31 potential risk factors emerged as univariate predictors of post-CEA hematoma formation (P < 0.05): general anesthesia, carotid shunt placement, intraoperative hypotension, nonreversal of heparin, neurosurgery service, and preoperative aspirin use. Following logistic regression only nonreversal of heparin, intraoperative hypotension, and carotid shunt placement were identified as multivariate predictors of post-CEA hematoma formation. More time was spent in critical care settings (ICU/PACU) (P < 0.01) and there was increased perioperative mortality (P = 0.04) within the hematoma group.ConclusionsPost-CEA hematoma formation is associated with increased morbidity and mortality. Non-reversal of heparin, intraoperative hypotension, and carotid shunt placement are multi-variate predictors of post-CEA hematoma formation.

Ansley, David M.; Sun, Jianhang; Visser, W. Anton; Dolman, John; Godin, David V.; Garnett, Maureen E.; Qayumi, A. Karim

doi: 10.1007/bf03013951pmid: 10442958

PurposeTo compare low vs high dose propofol and isoflurane on red cell RBC antioxidant capacity in patients during aortocoronary bypass surgery (ACBP).MethodsTwenty-one patients, for ACBR were anesthetized with sufentanil 0.5–10 μg·kg−1 and isoflurane 0–2%; ISO = control; n=7), or sufentanil 0.3 μg·kg−1, propofol 1–2.5 μg·kg−1 bolus then 100μg·kg−1 before, and 50 μg·kg−1·min−1 during CPB (LO; n=7), or sufentanil 0.3 μg·kg−1, propofol 2–2.5 μg·kg−1 bolus then 200 μg·kg−1·min−1 (HI; n=7). Venous blood was drawn pre-and post-induction, after 30 min CPB, 5, 10, and 30 min of reperfusion, and 120 min post-CPB to measure red cell antioxidant capacity (malondialdehyde (MDA) production in response to oxidative challenge with t-butyl hydrogen peroxide) and plasma propofol concentration. Preinduction blood samples were analyzed for antioxidant effects of nitrates on red cells. The tBHP concentration response curves for RBC MDA in ISO, LO and HI were determined.ResultsPreoperative nitrate therapy did not effect RBC MDA production. Perioperative RBC MDA production was similar in ISO and LO groups. Sustained intraoperative decrease in RBC MDA was seen with propofol 8.0 ± 2.4 − 11.8 ± 4.5 μg·ml−1 in HI (P < 0.05- 0.0001). MDA production vs log plasma propofol concentration was linear in HI dose.ConclusionsDuring CPB, RBC antioxidant capacity is enhanced and maintained with HI dose propofol. Propofol, at this dose, may prove useful in protecting against cardiopulmonary ischemia-reperfusion injury associated with ACBR

Kamitani, Kazuo; Higuchi, Akiko; Takebayashi, Takeshi; Miyamoto, Yuko; Yoshida, Hitoshi

doi: 10.1007/bf03013952pmid: 10442959

PurposeTo determine the effect of covering the patient’s head and face on the prevention of intraoperative hypothermia (<35.5°C).MethodsThis randomized, prospective trial included 44 adults undergoing elective abdominal surgery. After the induction of anesthesia with thiopental, in 44 patients their extremities and trunk were covered with towels and sheets. In addition, 22 patients (covered group) had their face and head fully covered. Anesthesia was maintained with N2O 50–66 % (2–3 L·min−1) and isoflurane (< IMAC) in oxygen combined with thoracic epidural anesthesia. Core temperature was measured at the tympanic membrane continuously and was recorded at 15 min intervals from the induction of anesthesia. Heat and moisture exchangers were used in their anesthetic circuit. Ambient temperature was maintained near 25°C.ResultsNeither group demonstrated intraoperative hypothermia. However, tympanic membrane temperature at 75, 90, 105 min in the covered group were higherthan those of control group (36.7 ± 0.4°C vs 36.5 ± 0.4°C, 36.8 ± 0.5°C vs 36.4 ± 0.5°C, 36.8 ± 0.5°C vs 36.4 ± 0.5°C, respectively, P < 0.05).ConclusionCovering the patient’s head and face maintains intraoperative core temperature.

Colbert, Sallyann T.; Curran, Emer; O’Hanlon, Deirdre M.; Moran, Ray; McCarroll, Maire

doi: 10.1007/bf03013953pmid: 10442960

PurposeNon Steroidal Anti-Inflammatory drugs have a well documented benefit in the relief of postoperative pain. This study was designed to compare the analgesic effect of intra-articular tenoxicam 20 mg with intravenous tenoxicam on postoperative pain in 88 patients undergoing day case knee arthroscopy.MethodsA prospective, double blind, randomized trial was performed. All patients received a standard general anesthetic. Patients in group A received 20 mg tenoxicam made up to 40 ml with normal saline intra-articularly (ia) and 2 ml normal salineiv. Patients in group B received 40 ml normal saline intra-articularly and 2 ml, 20 mg of tenoxicam,iv.ResultsBoth groups of patients were similar with respect to age, weight, sex and tourniquet inflation time. Patients receivingia tenoxicam had lower pain scores (at rest and upon movement) at 30, 60, 120 and 180 min postoperatively (0.8 ± 0.2vs 2.5 ± 0.2 at rest and 1.24 ± 0.2vs 3.4 ± 0.2 at movement at 60 min;P < 0.0001). Fewer patients required additional analgesia in the first four hours postoperatively (33%vs 84%;P < 0.00001) and the time to first analgesia (23.7 ± 11.2 vs 9.4 ± 0.6; P < 0.02) was longer in those receivingia tenoxicam,ConclusionIntra-articular tenoxicam provides superior postoperative analgesia and reduces postoperative analgesic requirements compared withiv tenoxicam in patients undergoing day case knee arthroscopy.

Koscielniak-Nielsen, Zbigniew J.; Nielsen, Per Rotbøll; Sørensen, Tommy; Stenør, Michael

doi: 10.1007/bf03013954pmid: 10442961

PurposeTo compare anesthetic time, success rate and adverse effects of axillary block by single or multiple injections of local anesthetic.MethodsTwo groups of patients were studied. In group T (targeted injections, n = 53) the four terminal nerves were located by electrical stimulation, and anesthetized with 5 ml mepivacaine 1% with epinephrine 5 μg·ml−1 (MEPE). In group S (single injection, n = 53) 80 mL MEPE 1% were injected into the neurovascular sheath, transarterially or after eliciting paresthesia. Patchy blocks were supplemented after 30 min. The patient was ready for surgery when analgesia was present in all areas distal to the elbow.ResultsThe block was complete at 11 min (6–15) in Group T and 7 min (5–13) in group S,P < 0.01. Supplementation was required in 46% in group S compared with 13% in group TP < 0.001: anesthesia time was 32 min (19–52) in group T and 39 min (16–58) in group S, P=0.02. The average doses of MEPE were 3.5 mg·kg−1 (2.4–5.6) in T group and 12.0 mg·kg−1 (8.9–16.4), in S group. However, 22% of patients in group T and 4% in group S reported tourniquet pain, P=0.02. Paresthesia was elicited in 42% of patients in group S and 8% in group TP < 0.001.ConclusionsSmall targeted injections of MEPE reduce total anesthetic time, give better spread of analgesia in the hand and forearm, and may be safer than a single large injection.

Aya, Antoine G. M.; Mangin, Roseline; Robert, Colette; Ferrer, Jean-Michel; Eledjam, Jean-Jacques

doi: 10.1007/bf03013955pmid: 10442962

PurposeTo evaluate the experience of the operator and the time of epidural anesthesia as factors contributing to unintentional dural puncture (UDP).MethodsIn a prospective analysis of recorded cases of UDP the following variables were recorded: maternal height, weight, and weight gain, type of personnel providing epidural analgesia, number of attempts, and hour of the epidural procedure. Work time was divided into day-time (8 AM to 7 PM) and night-time (7 PM to 8 AM), according to the change of coverage of the delivery suite. Night-time was divided into first (7 PM to midnight) and second parts (midnight to 8 AM). Relative risk was used to compare the incidence of UDP among different work-times.ResultsA total of 1489 consecutive epidural procedures were considered. The incidence of dural puncture was 0.8% (12 cases). The relative risk was higher for night-time than day-time (risk ratio 6.33; 95% confidence interval, 1.39 to 28.80;P = 0.006). Seven cases were caused by three operators with poor expertise, and five by two skilled obstetric anesthesiologists.ConclusionOperator experience and hour of procedure appear to be two important risk factors of UDP The increased risk of UDP in night-work could result from human factors such as fatigue, sleep deprivation or interruption.

Koh, Kwong Fah; Chen, Fun Gee; Cheong, Keng Fatt; Esuvaranathan, Vijaya

doi: 10.1007/bf03013956pmid: 10442963

PurposeTo compare the laryngeal mask airway (LMA) insertion conditions produced by propofol and a thiopental — low dose atracurium combination.MethodsIn a randomized controlled double blind study, 120 premedicated patients were allocated into four groups. After pre-oxygenation, anesthesia was induced as follows: I μg·kgt-1 fentanyl, 2.5 μg·kgt-1 propofol (group I); μg·kgt-1 fentanyl, 5 μg·kgt-1 thiopental (group II); I μg·kgt-1 fentanyl, 5 mg·kgt-1 thiopental, 0.05 mg·kgt-1 or 0.1 mg·kgt-1 atracurium (groups III and IV respectively). The LMA was insertedby a blinded anesthesiologist who also assessed the following insertion conditions on a three point scale; jaw relaxation, biting, gagging, coughing, presence of laryngospasm, adequacy of airway patency, number of attempts at insertion and overall insertion conditions.ResultsThere was no difference in insertion conditions between groups I, III and IV Group II produced the worst overall conditions (P < 0.05). There were no differences in hemodynamic changes and apnea times between all four groups.ConclusionThe combination of fentanyl-thiopental with low dose atracurium (0.05 or 0.1 mg·kgt-1) provided conditions comparable with those of propofol for LMA insertion.

Tsui, Ban C. H.; Gupta, Sunil; Finucane, Brendan

doi: 10.1007/bf03013957pmid: 10442964

PurposeTo report the detection of subarachnoid and intravascular catheter placement using nerve stimulation through an epidural catheter.Clinical featuresElectrical stimulation (1–10 mA) was applied through the catheter. A positive motor response (truncal or limb movement) indicated that the catheter was in the epidural space. Absence of a motor response indicated that it was not. A low milliamperage (< 1 mA) with bilateral response indicated subarachnoid placement. Intravascular catheter placement was indicated by a positive response to the test, which remains at or returns to the baseline levels (i.e. prior to any local anesthetic injection), despite the administration of local anesthetics. In the first patient, the test confirmed subarachnoid catheter placement during attempts at continuous spinal anaesthesia even though CSF could not be aspirated. Bilateral motor response in the legs was observed at 0.2 mA. In the second patient, inadvertent subarachnoid placement was detected during attempted lumbar epidural block by observing bilateral motor response in the legs at 0.3 mA. In the third patient, intravascular placement was suspected and confirmed by failure to obliterate the motor response despite repeated local anesthetic injection.ConclusionThe new test provides objective information in managing epidural catheters when their position is uncertain.

McTiernan, Christopher; Haagenvik, Bjørn

doi: 10.1007/bf03013958pmid: 10442965

PurposeThe anesthetic management of a parturient with Strümpell’s disease (hereditary or familial spastic paraparesis) who presented for Cesarean section is described. This neurological disorder is briefly reviewed and anesthetic implications of the condition are discussed.Clinical FeaturesA 30-yr-old woman in premature labour presented for Cesarean section. She had bilateral lower limb spastic paresis which had resulted in her being confined to a wheelchair from the age of 13 yr. A diagnosis of Strümpell’s disease had been made in childhood, She was currently receiving thromboprophylaxis, having suffered a deep venous thrombosis four weeks after a previous Cesarean section. The patient was in mild respiratory distress. Despite a history of uneventful general anesthesia and the aforementioned complicating factors, epidural anesthesia was considered the most appropriate technique in these circumstances. An epidural catheter was sited at the L3L4 interspace. Adequate anesthesia for the procedure was obtained after administration of 20 ml lidocaine 2% with 100 μg epinephrineand 100 μg fentanyl in saline. Postoperatively and at six month follow-up there were no neurological complications related to the use of epidural anesthesia.ConclusionStrümpell’s disease is an inherited progressive spastic paresis predominantly affecting the lower extremities. Epidural anesthesia appears to be an appropriate technique when administering anesthesia for Cesarean section under similar circumstances.