Showing papers in "Canadian Journal of Anaesthesia-journal Canadien D Anesthesie in 1997"

Association of mortality with age of blood transfused in septic ICU patients

Abstract: To determine, retrospectively, the age of packed red blood cell (PRBC) units transfused to patients admitted to the ICU with the diagnosis of severe sepsis and to correlate this vanable with outcome. All patients admitted to the ICU during 1992 with a diagnosis of severe sepsis were selected retrospectively. The criteria for the diagnosis of severe sepsis and septic shock were based on established guidelines. For each patient the total number of PRBC units transfused, the number of units transfused before, during and after the septic episode, and the age of each PRBC unit transfused were recorded. Of the 31 patients admitted to the ICU with severe sepsis, 19 died and 12 survived. No statistical differences between survivors and nonsurvivors were found with respect to age, sex, number of days in ICU, duration of sepsis, incidence of septic shock, admission Apache Il score or total number of PRBC units transfused. During sepsis the median age of PRBC units transfused to survivors was 17 days (range 5–35)vs 25 days (range 9–36) for nonsurvivors (P < 0.0001). A negative correlation (r = −0.73) was found between the proportion of PRBC units of a given age transfused to survivors and increasing age of PRBC. This is the first study to report a correlation of mortality with the age of PRBC transfused. The cause of this association is unclear. If this association is confirmed by a prospective randomised tnal it would have major implications for the use of PRBC in severe sepsis.

Critical care management of the obstetric patient

Abstract: To review a series of critically ill obstetric patients admitted to a general intensive care unit in a Canadian centre, to assess the spectrum of diseases, interventions required and outcome. A retrospective chart review was performed of obstetric patients admitted to the intensive care unit of an academic hospital with a high-risk obstetric service, dunng a five-year penod. Data obtained included the admission diagnosis. ICU course and outcome. Daily APACHE II and TISS scores were recorded. Sixty-five obstetric patients, representing 0.26% of deliveries in this hospital, were admitted to the ICU during the study period. All had received prenatal care. Admission diagnoses included obstetric (71%) and nonobstetric (29%) complications. The mean APACHE II score was 6.8 ± 4.2 and mean TISS score was 24 ± 8.1. Twenty-seven patients (42%) required mechanical ventilation. No maternal mortality occurred and the perinatal mortality rate was 11 %. A small proportion of obstetric patients develop complications requiring ICU admission. The out-come in this study was excellent, in contrast to that reported in other published studies with similar ICU admission rates. The universal availability of prenatal care may be an important factor in the outcome of this group of patients. The lack of a specific severity of illness scoring system for the pregnant patient makes comparison of case series difficult.

Music .increases satisfaction in elderly outpatients undergoing cataract surgery

Abstract: Music has long been known to reduce anxiety, minimize the need for sedatives, and make patients feel more at ease. The purpose of the study was to evaluate the effect of music in elderly outpatients undergoing elective cataract surgery with retrobulbar block and monitored anaesthetic care using fentanyl or alfentanil and midazolam. One hundred and twenty one patients were prospectively and randomly assigned to hear relaxing suggestions, white noise, operating room noise or relaxing music via audio-cassette headphones. Vital signs were documented before and after retrobulbar block and every 15 min thereafter. Anxiety was assessed using the State-Trait Anxiety Inventory (STAI) before and after surgery. Visual analogue scales (VAS) were used to assess anxiety and patient satisfaction postoperatively with a standardized questionnaire. Between group comparisons were made using Chi-Square, or ANOVA, where appropriate. There were no differences between groups in STAI or anxiety VAS scores at any time. Differences were noted in systolic blood pressure, but not in other vital signs. Patients’ ratings of the whole operative experience, satisfaction with the tape played, general level of relaxation and preference for the chosen tape for subsequent surgery were different (music > relaxing suggestions > white noise and OR noise, P< 0.05). Elderly patients undergoing cataract surgery under retrobulbar block were more satisfied with their experience if they heard relaxing music, rather than relaxing suggestions or white noise or OR noise. The type of auditory stimuli to which the patients were exposed did not influence the level of anxiety.

Postoperative analgesia withiv propacetamol and ketoprofen combination after disc surgery

Abstract: The concept of balanced analgesia suggests that a combination of analgesic drugs may enhance analgesia and reduce side effects after surgery. This study evaluated the effect of the combination of propacetamol (Prodafalgan) and ketoprofen (Profenid) after surgery of a hemiated disc of the lumbar spine. After randomization. 60 patients received: placebo (group 1); 2 g propacetamol (group 2); 50 mg ketoprofen (group 3); or a combination of 2 g propacetamol and 50 mg ketoprofen (group 4). Drugs were administered every six hours for two days after surgery. The patients used morphine with patient controlled analgesia pumps (bolus 1mg; lock out time 10 min) and were evaluated with a visual analogue scale (VAS) at rest and movement every six hours for two days. Side effects were noted. The patient characteristics and surgery were identical for each of the four groups. The VAS scores throughout the study were lower in group 4 than in groups 1, 2 and 3 both at rest (P < 0.05) and on movement (P < 0.01). The cumulative dose of morphine at 48 hr was lower in group 4 than in group 1 (23.4 ± 5 mg vs 58.9 ± 9 mg; P < 0.01) or group 2 (23.4 ± 5 mg vs 43.4 ± 6.6 mg; P < 0.05) and similar to that in group 3 (34.2 ± 4.5 mg). The incidence of side effects was similar in all groups. The combination of propacetamol and ketoprofen reduced pain scores both at rest and on movement. The drug combination did not reduce the morphine consumption and incidence of side effects.

Labour analgesia with intrathecal fentanyl decreases maternal stress

Abstract: Lumbar epidural analgesia (LEA) decreases maternal stress as measured by maternal circulating plasma catecholamine concentrations. Intrathecal fentanyl (ITF) provides effective labour analgesia but its effect on maternal epinephnne (Epi) and norepinephnine (NE) concentrations is not known. This study assesses whether ITF reduces maternal stress in the same manner as conventional LEA. Twenty-four healthy women in active labour received either 25 μ/g ITF (n = 12) or epidural lidocaine 1.5% (n = 12) for analgesia. Venous blood samples were collected before anaesthesia and at five minute intervals for 30 mm following anaesthesia for the measurement of plasma Epi and NE by high performance liquid chromatography. Maternal blood pressure (BP), heart rate (HR), visual analog scores (VAS) to pain and pruntus were recorded at the same time. Both ITF and LEA decreased pain VAS scores, maternal BP, and plasma Epi concentrations with only minimal effects on plasma NE concentrations. Intrathecal fentanyl (ITF) and LEA reduced plasma epi to a similar extent, with ITF reducing the levels slightly faster than LEA. Intrathecal fentanyi(ITF) and LEA reduced plasma Epi concentrations by 52% and 51%, respectively (P value < 0.01). We conclude that ITF is as effective as LEA in producing pain relief in the labounng patient. Intrathecal Fentanyl (ITF) is also capable of reducing maternal plasma epmephnne concentration, thus avoiding the possibly deleterious side effects of excess amounts of this catecholamme during labour.

Non-invasive quantification of diaphragm kinetics using m-mode sonography

Abstract: The standard conditions of spirometry (i.e., wearing a noseclip and breathing through a mouthpiece and a pneumotachograph) are likely to alter the ventilatory pattern. We used “time-motion” mode (M-mode) sonography to assess the changes in diaphragm kinetics induced by spirometry dunng quiet breathing. An M-mode sonographic study of the nght diaphragm was performed before and dunng standard spirometry in eight patients without respiratory disease (age 34 to 68 yr). During spirometry, the diaphragm inspiratory amplitude (DIA) increased from 1.34 ± 0.18 cm to 1.80 ± 0.18 cm (P = 0.007), whereas the diaphragmatic mspiratory time (T1 diaph) increased from 1.27 ± 0.15 to 1.53 ± 0.23 sec, (P = 0.015), without change in diaphragmatic total time interval (Ttot diaph). Therefore, the diaphragm duty cycle (T1 diaph /Ttot diaph) increased from 38% ± 1% to 44% ± 4% (P = 0.023). The diaphragm inspiratory (DIV) and expiratory (DEV) motion velocity increased (P = 0.007). M-mode sonography enabled us to demonstrate that the weanng of a nose clip and breathing through a mouthpiece and a pneumotachograph induce measurable changes in diaphragm kinetics.

Detection of intravascular injection of regional anaesthetics in children.

Abstract: Purpose: Detection of intravascular injection of local anaesthetic during placement of regional blocks in children by using epinephrine-induced tachycardia or hypertension may produce false positive and false negative findings. This study evaluates ECG changes as markers of intravascular injection of local anaesthetics with epinephrine, during placement of epidural blocks in children. Methods: Observational study in a teaching hospitaJ of all epiduraJ anaesthetics administered to paediatric patients during one year, General anaesthesia, where used, was not controlled. An ECG rhythm strip was recorded during test dose iniection and analyzed for changes in rate, rhythm, and T-wave configuration. Results: During the study period, 742 paediatric epidural blocks were administered. There were 644 caudal (284 without catheters), 97 lumbar, and one thoracic epidural anaesthetics. Satisfactory placement was achieved in 97.7% of patients. Intravascular injection was detected in 42 (5.6%) of epidural anaesthetics (3.8% and 6.7% of straight needle and catheter injections, respectively). Detection was by immediate aspiration of blood in six patients, and by heart t-ate increases >10 bpm in 30. Five had heart rate decreases suggesting a baroreceptor response. Five had heart rate increases 25%, and 29 (97%) had ECG changes in T-wave or rhythm in response to the epinephrine injection. There were no false positives. Conclusion: In order to reduce risks associated with epidural anaesthesia in children, epinephrine should be added to the local anaesthetic test dose, the ECG should be monitored continuously for changes in heart rate, rhythm, and T-wave amplitude. Epidural injections should be given in small increments.

Inhaled nitric oxide: clinical applications, indications, and toxicology

Abstract: Although the analogy of nitric oxide (NO) to Endothelium-derived Relaxing Factor remains controversial, medical use of exogenous NO gas by inhalation has grown exponentially. This review presents the mechanisms of action of inhaled NO in pulmonary hypertension, hypoxaemia, inflammation and œdema, as well as its therapeutic and diagnostic indications with emphasis on acute respiratory distress syndrome (ARDS) and toxicology. Two medical databases (Current Contents, Medline) were searched for citations containing the abovementionned key words to December 1996. Moreover, many presentations in congresses such as 4th International Meeting of Biology of Nitric Oxide, 52nd and 53rd Annual Meeting of Canadian Anaesthetists’ Society or 10th Annual Meeting of European Association of Cardiothoracic Anesthesiologists were used. Inhaled NO is now recognized as an invaluable tool in neonatal and paediatric critical care, and for heart/lung surgery. Other clinical applications in adults, such as chronic obstructive pulmonary disease and ARDS, require a cautious approach. The inhaled NO therapy is fairly inexpensive, but it would seem that it is not indicated for everybody with regards to the paradigm of its efficiency and potential toxicity. The recent discovery of its anti-inflammatory and extrapulmonary effects open new honzons for future applications. Clinical use of inhaled NO was mostly reported in case series, properly designed clinical trials must now be performed to establish its real therapeutic role. These trials would permit adequate selection of the cardiopulmonary disorders, and subsequently the patients that would maximally benefit from inhaled NO therapy,

Intravenous fentanyl PCA during labour

Abstract: l~sull~: Ini~ally, epidural analgesia was more effective (P = 0.0 I), and three patients in the fentanyl group were given epidural due to unsatisfactory pain relief. Overall satisfaction for analgesia did not differ between the groups. Maternal side-effects were more frequent in the fentanyl group (dizziness and tiredness most often, P = 0.0001 ). Severe sideeffects were not reported. In CTG there were no differences between groups. All the newboms were healthy, APGAR and pH were normal. Naloxone was not used. Neurological scoring was similar in both groups. In 12 hr monitoring heart rate, breathing frequency and movement time were similar in both groups, but SpO~ was lower in the fentanyt group (P < 0.00 I). Umbilical cord fentanyt concentrations were low or beyond the detection limit. Cx)nd~ion: Intravenous fentanyl can be used for labour analgesia with the doses reported here as an altemative to epidural analgesia. However, the fetus and neonate must be appropriately monitored. Naloxone and oxygen should be available if neonatal distress occurs.

Pre-emptive analgesia with ketamine, morphine and epidural lidocaine prior to total knee replacement

Abstract: Pre-emptive analgesia can improve postoperative pain management. The purpose of this study was to examine the effectiveness of ketamine as a pre-emptive analgesic as previous studies have shown the involvement of N-methyl-D-Aspartate (NMDA) receptor in neuroplasticity. Forty-five ASA 1–2 patients, undergoing unilateral total knee replacement were studied. In the study groups, epidural lidocaine was used as the primary anaesthestic. Patients received ketamine + morphine epidurally 30 min either before (group EB) or after skin incision (group EA). Group G patients received general anaesthesia and ketamine + morphine were given 30 min after skin incision via an epidural catheter used for postoperative pain control. Epidural morphine and ketamine in lidocaine was given to all patients at the end of surgery and every 12 hr for three days for analgesia supplemented with PCA morphine. The time until first PCA trigger, morphine consumption, pain scores, satisfaction scores, and morphine related side effects were recorded at 6, 12, 24, 48 and 72 hr after surgery. Epidural ketamine plus morphine with lidocaine before surgical incision produced better pain relief and patient satisfaction than when given after incision. A longer time to PCA and decreased morphine consumption were observed in group EB than in group G. In group EA, epidural anaesthesia also produced some pre-emptive analgesic effect compared with general anaesthesia shown by decreased morphine consumption. Administration of ketamine plus morphine with epidural lidocaine anaesthesia before surgery provided improved postoperative analgesia compared with general anaesthesia alone or when analgesics were given after skin incision.

Testing the raters: inter-rater reliability of standardized anaesthesia simulator performance.

Abstract: Assessment of physician performance has been a subjective process. An anaesthesia simulator could be used for a more structured and standardized evaluation but its reliability for this purpose is not known. We sought to determine if observers witnessing the same event in an anaesthesia simulator would agree on their rating of anaesthetist performance. The study had the approval of the research ethics board. Two one-hour clinical scenarios were developed, each containing five anaesthetic problems. For each problem, a rating scale defined the appropriate score (no response to the situation: score=0; compensating intervention defined as physiological correction: score= 1; corrective treatment: defined as definitive therapy score=2). Video tape recordings, for assessment of inter-rater reliability, were generated through role-playing with recording of the two scenarios three times each resulting in a total of 30 events to be evaluated. Two clinical anaesthetists, uninvolved in the development of the study and the clinical scenarios, reviewed and scored each of the 30 problems independently. The scores produced by the two observers were compared using the kappa statistic of agreement. The raters were in complete agreement on 29 of the 30 items. There was excellent inter-rater reliability (=0.96, P < 0.001). The use of videotapes allowed the scenarios to be scored by reproducing the same event for each observer. There was excellent inter-rater agreement within the confines of the study. Rating of video recordings of anaesthetist performance in a simulation setting can be used for scoring of performance. The validity of the scenarios and the scoring system for assessing clinician performance have yet to be determined.

The McCoy levering laryngoscope in patients with limited neck extension.

Abstract: The McCoy levenng laryngoscope is a modified Macintosh laryngoscope, which has a hinged tip controlled by a lever on the handle. The purpose of this study was to investigate whether the tip elevation of this laryngoscope results in better laryngeal visualization than using the Macintosh laryngoscope when the patient’s neck is fixed in the neutral position. Fifty female patients (ASA physical status I–II) undergoing elective surgery during general anaesthesia were investigated. The patient’s neck was manually fixed in the neutral position by an assistant, and laryngeal visualization was attempted first with a size #3 Macintosh laryngoscope (Macintosh trial), and then with a size #3 McCoy levering laryngoscope with blade tip elevation (McCoy trial), and tracheal intubation was attempted. Trials of laryngeal visualization were evaluated with the Cormadc score. In the Macintosh trial, 36 of 50 (72%) patients were evaluated grade 3, and two grade 4. In most of the patients graded 2 and 3 in the Macintosh trial (70% of the grade 2 and 83% of the grade 3 cases), the laryngeal view was improved by using the McCoy levering laryngoscope. The Cormack grade in the McCoy trial was less than that in the Macintosh tnal (P < 0.01). No complications were observed during the study. The McCoy levenng laryngoscope improved laryngeal visualization in patients whose neck cannot be extended. Le laryngoscope a levier de McCoy est un laryngoscope Macintosh modifie dont l’extremite articulee est controlee par un levier situee dans le manche. Cette etude visait a verifier si l’elevation de l’extremite de ce laryngoscope permettait de mieux visualiser le larynx que le laryngoscope de Macintosh quand la position de la tete etait maintenue en position neutre. Cinquante patientes (ASA I et II) soumises a une chirurgie gynecologique programmee non urgente sous anesthesie generale ont ete etudiees. Un assistant maintenait la tete en position neutre et apres avoir fait une premiere tentative de visualisation du larynx avec un laryngoscope Macintosh N∘ 3 (essai Macintosh) et l’avoir repetee avec un laryngoscope a levier McCoy N∘ 3 (essai McCoy), on essayait d’intuber la trachee. Les essais de visualisation laryngee etaient evalues sur l’echelle de Cormack. Durant l’essai Macintosh, 36 patientes sur 70 (72%) etaient considerees grade 3 et deux, grade 4. Chez la plupart des patientes grade 2 et 3 pendant l’essai Macintosh (70% des grades 2 et 83% des grades 3), la visualisation de la trachee etait amelioree par le laryngoscope McCoy. Les grades de Cormack pendant l’essai McCoy etaient infeneurs a ceux de l’essai Macintosh (P < 0.01). Aucune complication n’a ete observee. Le laryngoscope de McCoy ameliore la visualisation de la trachee lorsque le cou n’est pas en extension.

Clonidine at induction reduces shivering after general anaesthesia

Abstract: Purpose Postanaesthetic shivering occurs in 5–65% of patients. In addition to causing discomfort. it is associated with deleterious consequences. Our objective was to investigate the effect of 150μg clonidine, at induction of anaesthesia, on penoperative core and peripheral temperature, incidence of postanaesthetic shivering and patients’ perception of cold.

The cost for construction and operation of a simulation centre

Abstract: Lack of financial information results in planning difficulties and may delay the introduction of simulator based education. We collected data from an existing simulation centre and describe a construction and operating budget to facilitate planning and construction for interested institutions. After obtaining approval from the managing board, the plans and financial statements of the Canadian Simulation Centre, Sunnybrook Health Science Centre, University of Toronto were reviewed from the penod from July 1994 through June 1996. Costs were calculated from the financial reports and separated into construction and operation phases. A list of the ongoing educational and research activities was compiled. All dollar figures are expressed in 1996 Canadian Dollars. The planning and construction took place from July 1994 through June 1995. Construction costs for the simulation centre totalled $665,000, of which 85% was related to capital equipment purchases and 15% for salary support. The net costs of ongoing education and research activities (3.35 days/week) were $ 167.250 from July 1995 through June 1996. About 65% of this consisted of salary support and was absorbed by the existing educational resources of the University of Toronto Department of Anaesthesia. Substantial resources are required for the construction of a simulation centre ($665,000) primarily because of capital equipment purchases. However, there is also a considerable operating cost per year ($ 167,250) which consists mostly of salary support.

Airway and respiratory management following non-lethal hanging.

Abstract: Purpose To review the literature on airway and respiratory management following non-lethal (suicidal) hanging and to describe the anatomy, mjury and pathophysiological sequelae and their impact on patient care.

Epidural analgesia for labour and delivery: informed consent issues.

Abstract: Objective Many anaesthetists believe that informed consent for epidural analgesia during labour is inadequate. Patients are perceived to be poorly informed and unable to cope with the information given during labour for informed consent. We reviewed these two hypotheses: A) to define complications for which patients want information; B) to quantify the influence of pain, anxiety, opioid premedication, and the importance of level of education, on a patient’s level of satisfaction with regard to the consent process; and C) to assess how satisfactory epidural pain relief correlates with satisfaction with the consent process.

A comparison of three regional anaesthesia techniques for outpatient knee arthroscopy

Abstract: The purpose of this study was to compare intraoperative conditions and postoperative pain control of three penpheral regional anaesthesia techniques for outpatient knee arthroscopic procedures. Sixty patients were randomized to one of three groups. Group IA received portal injections (10 ml lidocaine 1%), intraarticular lidocaine (20 ml CO2 lidocaine 2% with 1/200.000 adrenaline) and a placebo femoral nerve block (20 ml saline). Group FNB received a femoral 3-in-1 nerve block (20 ml chloroprocaine 2% with 1/200.000 adrenaline), placebo portal injections (10 ml saline) and placebo intraarticular saline (20 ml saline with 1/200.000 adrenaline). Group FNB + IA received a femoral 3-m-1 nerve block, intraarticular hdocaine and placebo portal injections. The following were assessed: intraoperative pain (10 cm VAS: 0 = no pain. 10 = extreme pain), surgical operating conditions (1 = excellent. 4 = unacceptable), intraoperative use of sedation and analgesia, time to discharge, patient satisfaction score (1= very satisfied, 5 very unsatisfied) and postoperative analgesia. Data were analyzed using ANOVA, Kruskal-Wallis, and Chi-square tests as appropriate. P 5) was expenenced by 20/54 (37%) patients. Any of the three anaesthetic techniques tested provide reliable intraoperative patient and surgical conditions for outpatient knee arthroscopy. Patient discomfort postoperatively was considerable in all groups and requires further investigation.

Halothane and isoflurane enhance melanoma tumour metastasis in mice.

Abstract: To investigate the incidence of tumour metastasis from B16 melanoma tumour cells in expenmental animals following exposure to equipotent concentrations of halothane or isoflurane, and to differentiate if exposure to one anaesthetic resulted in greater metastases than the other. Experimental animals (C57B1 mice), were randomized to receive 1.3 MAC hours of halothane or isoflurane anaesthesia. The control group of animals received oxygen alone under identical conditions. Fifteen minutes after completion of anaesthesia, control and experimental groups were given 1 × 105 B16 melanoma cells intravenously. After 21 days, all animals were autopsied, and the metastatic nodules in their lungs were counted. The difference in the numbers of metastatic nodules between control and expenmental groups of animals was analyzed for significance by the Mann Whitney “U test”. More metastases were observed in the animals exposed to halothane (37.28±5.08, P< 0.0001), or isoflurane anaesthesia (28.24±4.07, P< 0.0014) than in the control animals (12.22± 1.52). Exposure to halothane or isoflurane anaesthesia increased the number of pulmonary metastases in C57B1 mice compared with the control groups but there was no difference in metastases among animals treated with halothane or isoflurane.

Relationship of fat embolism to haemodynamic and echocardiographic changes during cemented arthroplasty

Abstract: Purpose Pressurisation of the medullary cavity during cemented arthroplasty causes “intravasation” of marrow fat. The purpose of this study was to examine the relationship between the amount of pulmonary intravascular fat and the haemodynamic and echocardiographic changes.

Combined spinal and epidural anaesthesia for major abdominal surgery in infants.

Abstract: Subarachnoid anaesthesia is becoming increasingly popular in neonates and infants. However, single dose spinal anaesthesia is of limited value for major abdominal surgery in infants due to its short duration of action and inability to provide analgesia in the post operative period. A new technique of combined spinal and epidural anaesthesia for major abdominal surgery in the infant is described. Data were gathered prospectivety from 19 infants presenting for upper and lower abdominal surgery. Anaesthesia was induced with a subarachnoid injection of tetracaine. After the subarachnoid block was established, an epidural catheter was placed for further intraoperative and postoperative management. Data collected included age and weight of the patients, type and duration of the surgical procedure. Doses of local anaesthetics as well as the need for intraoperative and postoperative supplements were recorded. An illustrative case report is provided. Infants studied represented a wide range of weights (1520–7840 g). Spinal anaesthesia was successful in all 19 patients. A variety of extensive surgical procedures including small bowel resections and various genitounnary procedures were successfully performed. In 17 patients a functioning epidural catheter was in place postoperatively. In these patients effective analgesia was maintained with dilute solutions of epidural bupivacaine. Only three doses of narcotic were required for pain control. No patient required postoperative mechanical ventilation or tracheal intubation. Combined spinal and epidural anaesthesia is a potential option to general anaesthesia for major abdominal surgery in infants.

Peri-operative multimodal pain therapy for caesarean section: analgesia and fitness for discharge.

Abstract: To compare, the efficacy of a multi-modal analgesic regimen and single drug therapy with iv PCA morphine after Caesarean delivery with spinal anaesthesia. Forty ASA 1–2 partunents presenting for elective Caesarean section were randomized to receive multimodal pain treatment with intrathecal morphine, incisional bupivacaine and ibuprofen + acetaminophenpo until hospital discharge (Group 1) or conventional therapy withiv PCA morphine weaned to acetaminophen + codeinepo. (Group 2). Both groups received spinal anaesthesia with 1.7 ml hyperbanc bupivacaine 0.75%. Visual analog pain scores at rest (RVAPS) and with movement (DVAPS) were recorded q 2 hr during the first 24 hr, then q 4 hr until discharge. Time to first walking, eating solid food, flatus, bowel movement. voiding and hospital discharge were recorded. Pain scores were lower in Group 1 patients during the first 24 hr after spinal injection RVAPS 0.6 ± 0.1 in Group 1vs 2.1 ± 0.1 in Group 2 (mean ± SEM), DVAPS 1.9 ± 0.1 in Group 1 vs 4.1 ± 0.1 in Group 2 (P < 0.0001). Times to first flatus, 36.1 hr ± 2.9 vs 20.5 ± 1.8 (P < 0.05) and to first bowel movement. 74.8 hr ± 5.6vs 57.4 ± 4 7 (P < 0.0001) were longer in Group 2 patients. There was no difference between groups in time to eating solid food, walking or hospital discharge. Multi-modal pain therapy resulted in improved early post-operative analgesia dunng the first 24 hr after Caesarean delivery. Patients receivingiv PCA morphine followed by acetaminophen + codeine po were more likely to develop decreased bowel mobility. All patients, with one exception, achieved discharge cntena (eating solid food, absence of nausea, normal lochia. dry incision and DVAPS < 4) at 48 hr after spinal injection.

Treatment of intrathecal morphine-induced pruritus following Caesarean section

Abstract: To compare both the efficacy and cost of nalbuphine and diphenhydramine in the treatment of intrathecal morphine-induced pruritus following Caesarean section. Eighty patients, undergoing elective Caesarean section under spinal anaesthesia, were randomized, in a prospective, double-blind trial, to receive either nalbuphine (Group NAL) or diphenhydramine (Group DIP) for the treatment of SAB morphine-induced pruritus. All patients received an intrathecal injection of 10–12 mg hyperbaric bupivacaine 0.75% and 200 μg preservative free morphine. Postoperative pruritus was assessed, using a visual analogue scale (VAS), for 24 hr. Pruritus treatment was administered upon patient request and by a nurse blinded to the treatment given. Patients who failed to respond to three doses of the study drug were deemed treatment failures. Patient satisfaction was assessed with a questionnaire given 24 to 48 hr after surgery. Direct drug costs were calculated based on the pharmacy provision costs as of April 1996. Eighty patients were enrolled and 45 requested treatment for pruritus. Patients treated with NAL (n = 24) were more likely to achieve a VAS score of zero with treatment (83% vs 43%, P < 0.01), had a higher ΔVAS following treatment (4 ± 2 vs 2 ± 2, P < 0.003), and experienced fewer treatment failures (4% vs 29%, P < 0.04), than those treated with DIP (n = 21). Group NAL patients were also more likely to rate their pruritus treatment as being good to excellent (96% vs 57%, P < 0.004). Direct drug costs were higher for NAL than for DIP ($6.4 ± 3.1 vs $ 1.7 ± 0.7, respectively, P < 0.0001). Nalbuphine is more effective than diphenhydramine in relieving pruritus caused by intrathecal morphine and the cost differences are small.

Low and minimal flow inhalational anaesthesia.

Abstract: To descnbe the pharmacokinetic behaviour and practical aspects of low (0.5–1l· min−1) and minimal (0.25–0.5 l · min−1) flow anaesthesia. A Medline search located articles on low flow anaesthesia, and computer simulated anaesthetic uptake models are used. Most, 85–90%, of anaesthetists use high fresh gas flow rates during inhalational anaesthesia. Low/minimal flow anaesthesia with a circle circuit may avoid the need for in-circuit humidifiers, raise the temperature of inspired gases by up to 6°C, reduce cost by about 25% by reduction of fresh gas flows to 1.51· mm−1, and reduce environmental pollution with scavenged gas. Knowledge of volatile anaesthetic pharmacokinetic behaviour facilitates the use of minimal/low flow rates. Small amounts of nitrogen or minute amounts of methane, acetone, carbon monoxide, and inert gases in the circuit are of no concern, but the degradation of desflurane (to carbon monoxide by dry absorbent) and sevoflurane (to compound A by using a fresh gas flow of >2 l · min−1) must be avoided. With modem gas monitoring technology, safety should be no more of a concern than with high flow techniques. The use of fresh gas flow rates of < 1l · min−1 for maintenance of anaesthesia has many advantages, and should be encouraged for inhalational anaesthesia with most modem volatile anaesthetics.

Cement implantation syndrome: a time limited embolic phenomenon.

Abstract: C EMENTED arthroplasty is among the most common and effective surgical procedures performed for elderly patients. The cement implantation syndrome is a well-recognized complication of this procedure, characterized by systemic hypotension, pulmonary hypertension and oxygen desaturation at the time of cement and prosthesis insertion. ~ This syndrome is now thought to be caused by the haemodynamic effects of emboli and not by the toxic properties of methyl methacrylate monomer. Embolization results from high intramedullary pressures. The cement acts as a seal, preventing decompression during prosthesis insertion and the resultant high intramedullary pressure forces medullary contents into the vasculature. 2 As well as the physical effects of mechanical pulmonary vascular obstruction, the embolized material may contain vasoactive substances that initiate mediator release or create reflex changes that increase pulmonary vascular tone. Non-cemented arthroplasty is associated with fewer emboli, lower intramedullary pressures and considerably less haemodynamic disturbance) Life-threatening hypotension during cemented arthroplasty is rare, yet sudden tmexplained intra-operafive cardiac arrests continue to be reported. 4-6 In this issue of the journal the Anaesthesia Advisory Committee to Ontario's Chief Coroner (Pietak et al.) report on four deaths that appear to be examples of the cement implantation syndrome. 7 They correctly emphasize the need for clinical awareness of such potential complications and an immediate resuscitation protocol. They suggest that the protocol be based on the pathophysiology of acute fight ventricular (RV) failure. Also in this issue of the journal, Lafont et al. using transoesophageal echocardiography (TEE) report that 47 of 48 patients undergoing elective cemented hip arthroplasty had detectable emboli, s Lafont et al., however, have not studied the cement implantation syndrome as no patients in the study developed hypotension or desaturation. Clinical reports and laboratory studies of the cement implantation syndrome all point to RV failure secondary to increased pulmonary artery pressure (PAP) as the underlying cause of systemic hypotension and sudden cardiac arrest. 9,1~ With acute increases in pulmonary vascular resistance (PVR), the thin-walled, compliant RV rapidly dilates with a shift of the interventricular septum to the left within the restrictions imposed by the pericardial cavity. These changes cause an immediate decrease in left ventricular (LV) compliance, reduced LV filling and cardiac output. Coronary perfusion pressure is decreased by the hypotension and right coronary flow is reduced as RV end-diastolic pressure (RVEDP) increases, creating ischaemia. In a recent report, Urban et al. described four patients with a mean increase in PAP of 10 mmHg and considerably decreased RV ejection fractions from 53% to 36%. 9 These changes can occur within seconds of prosthesis insertion and can be complicated by systemic paradoxical emboli. Pietak et al. suggest that some high risk groups can be identified. 7 Patients with limited pre-operative cardiopulmonary reserve due to pre-e~sting pulmonary hypertension, RV dysfunction or coronary artery disease, are susceptible to ischaemia and infarction. They may be particularly at risk if the surgical procedure is chosen that results in a large embolic load. Haemodynamic instability at the time of cement and prosthesis insertion is a surgical complication. Technical factors can increase the embolic load. Some prostheses, such as the Guepar long-stemmed bipolar knee arthroplasty, are clearly associated with an extraordinarily increased risk) 1 Urban's report suggests that revision arthroplasty patients also have a high incidence of increased PAP with reduced ejection fractions. 9 Several patients (4 /14) required increased inotropic support with one death. Arthroplasty for pathological fractures may be a risk factor, perhaps related to pressurization of abnormal vessels in cancerous bone. However, some preventative methods (eg. drilling a venting hole in the cortical bone to

Propofol or midazolam for sedation and early extubation following cardiac surgery

Abstract: The purpose of this randomized, double-blind study was to evaluate the efficacy of midazolam and propofol for postoperative sedation and early extubation following cardiac surgery. ASA physical status II-III patients scheduled to undergo elective first-time cardiac surgery with an ejection fraction > 45% were eligible. All patients received a standardized sufentanil/isoflurane anaesthesa. Dunng cardiopulmonary bypass 100 μg · kg−1· mm−1 propofol was substituted for isoflurane. Upon amval in the Intensive Care Unit (ICU). patients were randomized to either 10 μg · kg · min−1 propofol (n = 21) or 0.25 μg · kg · mm−1 midazolam (n = 20). Infusion rates were adjusted to maintain sedation within a predetermined range (Ramsay 2–4). The infuson was terminated after four hours. Patients were weaned from mechanical ventilation and their tracheas extubated when haemodynamic stability, haemostasis, normothermia and mental orientation were confirmed. Haemodynamic measurements, artenal blood gas tensions and pulmonary function tests were recorded at specified times. There were no differences between the two groups for the time spent at each level of sedation, number of infusion rate adjustments, amount of analgesic and vasoactive drugs, times to awakening and extubation. The costs of propofol were higher than those of midazolam. There were no differences in haemodynamic values, artenal blood gas tensions and pulmonary function. We conclude that midazolam and propofol are safe and effective sedative agents permitting early extubation in this selected cardiac patient population but propofol costs were higher.

Ketamine inhibits nitric oxide synthase in lipopolysaccharide-treated rat alveolar macrophages

Abstract: To evaluate the effects of ketamine on the activity and protein expression of inducible nitric oxide synthase (iNOS) induced by lipopolysaccharide (LPS) in rat alveolar macrophages. Pulmonary alveolar macrophages isolated from Wistar-Kyoto rats were used. After incubation of macrophages with ketamine (1,10, or 100μM) and LPS (1μg· ml−1) for 24 hr, the cell-free medium was removed for measuring the nitrite and tumour necrosis factor-α (TNF-α) levels by Griess reaction and ELISA kit, respectively. The harvested macrophages were also used to determine the activity of iNOS by using the conversion of [3H]-Larginine to [3H]-L-citruliine method. In addition, the protein expression of iNOS was detected by Western blot analysis. In rat alveolar macrophages, (1) ketamine (1 to 100 μM) caused a dose-dependent suppression of the production of nitrite and TNF-α induced by LPS and (ii) ketamine (100 μM) inhibited the activity (46.5 ± 4.8%, P < 0.05) and protein expression (35 ± 11%, P < 0.05) of iNOS in response to LPS. These results show that ketamine inhibits the activity and expression of iNOS in LPS-activated alveolar macrophages, which may be associated with the reduction of the release of TNF-α following LPS treatment.

Natural inhibitors of cholinesterases: implications for adverse drug reactions

Abstract: Acetylchomesterase and butyrylcholinesterase are two closely related enzymes important in the metabolism of acetylcholine and anaesthetic drugs, including succinylcholine. mvacunum. and cocaine. The sdanaceous glycoalkaloids (SGAs) are naturally occurring steroids in potatoes and related plants that inhibitboth acetylcholinesterase and butyrylcholinesterase. There are many clinical examples of direct SGA toxicity due to cholinesterase inhibition. The aim of thus study was to review the hypotheses that (I) SGAs may be the evolutionary driving force for atypical butyrytcholinesterase alletes and that (2) SGAs may adversely influence the actions of anaesthetic drugs that are metabolized by acetyicholinesterase and butyrylcholinesterase. The information was obtained by Medicine search and consultation with experts in the study of SGAs and cholinesterases. The SGAs inhibrt both acetyicholinesterase and butyrylcholinesterase in numerousin vitro andin vivo experiments. Although accurate assays of SGA levels are difficult, published data indicate human serum SGA concentrations at least ten-fold lower than required to inhibit acetyicholinesterase and butyrylcholinesterasein vitro. However, we review evidence that suggests the detary ingestion of SGAs can initiate a cholinergic syndrome in humans. This syndrome appears to occur at SGA levels lower than those which interfere with anaesthetic drug catabolism. The world distribution of solanaceous plants parallels the distribution of atypical alleles of butyrylcholinesterase and may explain the genetic diversity of the butyrylcholinesterase gene. Correlative evidence suggests that dietary SGAs may be the driving force for atypical butyrylcholinesterase alleles. In addition. SGAs may influence the metabolism of anaesthetic drugs and this hypothesis warrants experimental investigation.

Gastric fluid measurement by blind aspiration in paediatric patients: a gastroscopic evaluation.

Abstract: Methods: This is a prospective study of 17 patients aged six months to I I yr who underwent elective upper endoscopy at a paediatric teaching hospital. Gastric contents were aspirated blindly with a syringe and a 16 or 18F multi-orificed orogastnc tube, and the volume of gastric contents removed in the supine and decubitus positions was measured. Residual gastric fluid was aspirated using an endoscope. Data from 611 infants and children enrolled in previously published studies utilizing the same blind aspiration technique were pooled and a gastric fluid volume frequency distribution was created. Results: Blind aspiration removed 97 +_ 896 of the total gastric fluid volume. In 661 children presenting for elective surgery, the gastric fluid volume was 0.40 _ 0.45 ml'kg -~. Median volume was 0.27 ml'kg -~ , with the 95%ile at 1.25 ml-kg-' and an upper limit of 4. I ml'kg -~. Conclusion: Blind aspiration of gastric contents accurately estimates gastric fluid volume for paediatric patients fasted for surgery. Population estimates for gastric fluid volume in otherwise healthy fasted paediatric patients are shown.

Double-blind comparison of epidural ropivacaine 0.25% and bupivacaine 0.25%, for the relief of childbirth pain

Abstract: Purpose To evaluate the efficacy of ropivacaine 0.25% when administered epidurally for relief of labour pain and to compare it with bupivacaine 0.25%.

Conscious sedation for interventional neuroradiology: a comparison of midazolam and propofol infusion.

Abstract: Purpose The aim of this study was to compare two conscious sedation techniques, midazolam (M) and propofol (P), for interventional neuroradiology by assessment of the incidence of complications and satisfaction scores.