RNA-Catalyzed RNA Ligation within Prebiotically Plausible Model Protocells.

Demonstrating RNA catalysis within prebiotically relevant models of primordial cells (protocells) remains a challenge in origins of life research. Fatty acid vesicles encapsulating genomic and catalytic RNAs (ribozymes) are attractive models for protocells; however, RNA catalysis has largely been incompatible with fatty acid vesicles due to their instability in the presence of Mg2+ at the concentrations required for ribozyme function. Here, we report a ribozyme that catalyzes template-directed RNA ligation at low Mg2+ concentrations and thus remains active within stable vesicles. Ribose and adenine, both prebiotically relevant molecules, were found to greatly reduce Mg2+ -induced RNA leakage from vesicles. When we co-encapsulated the ribozyme, substrate, and template within fatty acid vesicles, we observed efficient RNA-catalyzed RNA ligation upon subsequent addition of Mg2+ . Our work shows that RNA-catalyzed RNA assembly can occur efficiently within prebiotically plausible fatty acid vesicles and represents a step toward the replication of primordial genomes within self-replicating protocells.

Analgesic efficacy of ketorolac 0.5% ophthalmic solution (Accular) in paediatric strabismus surgery.

This prospective double-blind study was designed to assess the analgesic efficacy of ketorolac 0.5% ophthalmic solution compared with placebo in 30 healthy children undergoing extraocular muscle recession for correction of strabismus. After paracetamol 20 mg.kg-1 preoperatively, a standard anaesthetic was given. There were no significant differences in Children's Hospital of Eastern Ontario Pain Scale (CHEOPS) and faces pain scale (FPS) scores, requirement for supplementary analgesia or in postoperative vomiting between the two groups over the following 24 h. This study did not demonstrate improved postoperative analgesia when topical ketorolac eye drops were given in addition to paracetamol. This observed lack of efficacy may reflect difficulties in the use of CHEOPS and FPS in this age group with this pain model.

Electrocardiographic monitoring in healthy young adult outpatients: mandatory or optional?

PURPOSE: To determine the incidence and duration of ECG abnormalities in healthy adults during short duration outpatient surgery and their relationship to important clinical events. METHOD: In 381, ASA Class I, day surgery patients undergoing short surgical procedures the ECG was monitored prospectively for evidence of abnormalities. The attending anaesthetist administered the anaesthetic and made all clinical decisions while relying on routine monitors (ECG, oximeter, BP, capnometer, oxygen analyser, low pressure alarm and anaesthetic gas monitors). Intra-operative events of clinical significance (e.g., light anaesthesia, regurgitation, coughing, hypotension, arterial desaturation, hiccoughs etc), ECG abnormalities and their duration were documented. RESULTS: Electrocardiographic abnormalities were detected in 21% of patients as follows: sinus tachycardia (11%), artifacts (7%), premature atrial contractions (1.6%), lead disconnects (1%), sinus bradycardia (0.5%) and premature ventricular contractions (0.3%). All abnormalities resolved spontaneously within three minutes. Intra-operative incidents of consequence occurred in only 2.6%: light anaesthesia (5), arterial desaturation > 5% (2), hypotension (1), hiccough (1) and regurgitation (1). All incidents were detected clinically and by pulse oximetry. The ECG did not detect any of the incidents and was normal during the events. CONCLUSION: Routine ECG monitoring did not detect intra-operative incidents in healthy adults during short outpatient procedures. Detected ECG abnormalities were benign and resolved spontaneously within three minutes. Firm conclusions as to the safety implications of withdrawing ECG monitoring cannot be drawn from this study. Guidelines may need to be reviewed to determine whether ECG monitoring in such cases should be optional rather than mandatory.

Readmission for bleeding after outpatient surgery.

PURPOSE: To examine the frequency of readmission due to surgical bleeding after ambulatory surgery. METHODS: A retrospective review of hospital records for patients readmitted to the same hospital after surgery in our Daycare centre was conducted for January 1984 to December 1992. The charts of all patients readmitted to hospital within 48 hr of surgery were examined. Readmissions for bleeding were studied with respect to demographics, time when bleeding occurred after arrival in PACU(latent interval) and treatment. Matched controls were identified and a case-control analysis performed to identify factors associated with an increased risk of readmission from bleeding. RESULTS: There were 172,710 outpatient procedures and 64 readmission for bleeding (0.04%). Gynaecological and urological surgery accounted for the highest number of bleeders (86%). Most patients who bled excessively in the OR continued to bleed in PACU. Those who bled in the PACU alone had a latent interval of 54 +/- 77 min. Those who bled both in the OR and PACU had a latent interval of 20 +/- 7 min. Those who bled mainly at home had a latent interval of 104 +/- 68 min. A majority of bleeders could have been identified if they had been observed for 30-45 min. Logistic regression of case-control matches did not identify any risk factor likely to increase the risk of readmission in bleeders. CONCLUSIONS: Bleeding after outpatient surgery is uncommon and discharge criteria need to be re-examined in order to take this into account and permit appropriate fast tracking of outpatients.

The effectiveness of clonidine as an analgesic in paediatric adenotonsillectomy.

PURPOSE: To compare the analgesic effects of preoperative oral clonidine with intraoperative intravenous fentanyl in children undergoing tonsillectomy or adenotonsillectomy. METHODS: This randomized, controlled, double-blind study of 36 ASA I-II children, age 7-12 yr undergoing adenotonsillectomy was conducted at a tertiary care paediatric teaching hospital. Either 4 micrograms.kg-1 clonidine po was given 60-90 min preoperatively or 3 micrograms.kg-1 fentanyl i.v. was given intraoperatively. Postoperatively visual analog pain scores (VAS) were recorded at rest and on swallowing every 10 min for the first 30 min and then every 15 min for two hours. Morphine 0.05 mg.kg-1 i.v. was given for VAS > or = 5. If > 3 doses were required, 1.5 mg.kg-1 codeine po and 20 mg.kg-1 acetaminophen po were given. Sedation and anxiety scores were recorded preoperatively. Haemodynamic changes, blood loss, recovery scores, and the incidence of vomiting, hypotension, and airway obstruction were recorded. RESULTS: Children who received clonidine had a higher incidence of preoperative sedation (63%) than those receiving fentanyl (6%). Preinduction mean arterial pressure was lower in the clonidine group but required no intervention. VAS scores were similar throughout the observation period. There was no difference either in the number of morphine or codeine rescue doses administered or in the incidence of side effects. CONCLUSION: Oral clonidine is an effective analgesic and sedative for children undergoing tonsillectomy or adenotonsillectomy.

Acupressure for intrathecal narcotic-induced nausea and vomiting after caesarean section.

In this randomized double-blind trial we investigated the effect of acupressure on the incidence of nausea and vomiting after caesarean section under spinal anaesthesia with added intrathecal morphine. Parturients wore either acupressure or placebo wristbands during surgery and postoperatively for at least 10 h. There was no significant difference overall between the two groups in the incidence of intra- or postoperative nausea or vomiting/retching. Demand for antiemetic medication was also similar in the two groups. However, in the sub-group of parturients who gave a previous history of postoperative nausea or vomiting, there was a statistically significant reduction in both postoperative nausea and vomiting/retching in the acupressure group. Further investigations are needed to see whether acupressure may be an effective non-pharmacological, non-invasive treatment for a common problem in this sub-group of patients.

Pharmacoeconomics of intravenous regional anaesthesia vs general anaesthesia for outpatient hand surgery.

PURPOSE: To compare the cost and effectiveness of intravenous regional anaesthesia (IVRA) with general anaesthesia (GA) for outpatient hand surgery. METHOD: A retrospective record analysis of 121 patients who received IVRA were compared with 64 patients who received GA in our Daycare centre. The costs of anaesthesia and recovery were calculated from an institutional perspective using 1995 Canadian Dollar values. Effectiveness was measured in terms of time for anaesthesia, recovery and discharge, % with unsatisfactory anaesthesia and complications. RESULTS: Both groups were well matched in terms of weight, sex and ASA class. Patients in the IVRA group were older (45 +/- 16 vs 38 +/- 13 yr) and had a lower frequency of two types of operation. The median total cost for the IVRA group of $24.60 (15.76-55.29) was less than that for the GA group of +f448.66 (35.59-73.11), (P < 0.00001). Anaesthesia was unsatisfactory in 11% of the IVRA group, but in none having GA,(P < 0.01). Recovery was faster in the IVRA group with a median time to discharge of 70 (35-180) min compared with 118 (45-320) min in the GA group, (P < 0.00001). Vomiting requiring treatment occurred in 5% of the GA group, but in none having IVRA, (P < 0.05). Dizziness which delayed discharged also occurred in 5% of the GA group, but in none having IVRA, (P < 0.05). CONCLUSION: The cost of anaesthesia and recovery using IVRA for outpatient hand surgery was half that of GA. intravenous regional anaesthesia was less effective than GA in achieving satisfactory anaesthesia, equally effective in time to administer anaesthesia, and more effective in speeding recovery and minimising postoperative complications.

Beneficial effect of both tranexamic acid and aprotinin on blood loss reduction in reoperative valve replacement surgery.

BACKGROUND: Blood loss after cardiac surgery is a continuing concern of caregivers and patients. The acute inflammatory reaction initiated by the extracorporeal circuitry, necessary to perform the procedure, stimulates the coagulation cascade, and the resultant hyperfibrinolysis is considered to be a major contributing factor of blood loss. The necessity to reduce transfused blood products after cardiac surgery is important, as it reduces the potential transmission of serious viral infections, improves operative outcomes, and provides containment of costs. The purpose of this study was to compare the effect of synthetic antifibrinolytic tranexamic acid with naturally occurring antifibrinolytic aprotinin on blood loss and to study requirements for transfusion of blood products after repeat cardiac valve surgery. METHODS AND RESULTS: Two randomized trials had been previously conducted, each comparing the respective treatment groups, aprotonin (AP group) and transexamic acid (TA group), with a control group [placebo (P)] in double-blind fashion with the same inclusion and exclusion criteria. The number of patients in the four designated groups are as follows: TA, 22; TA-P, 19; AP, 24; and AP-P, 36. The dosage of aprotinin (high-dose) encompassed a 280-mg loading dose infused after induction of anesthesia, 280 mg in the CPB prime solution, and 70 mg/h for a period of 6 hours. The tranexamic acid dose was 10 mg infused in 500 mL of normal saline. The blood loss was measured intraoperatively and postoperatively. The transfusion of homologous blood products was conducted in a standardized fashion. Both the TA and AP groups lost less blood intraoperatively, in total, less than either of the placebo groups, and less blood postoperatively than the TA-P group (P<.05). The postoperative blood loss (median) was 538 mL for the TA group, 455 mL for the AP group, and for the respective placebo groups, 1170 mL and 595 mL. The total blood loss was 1340 mL for the TA group, 1383 mL for the AP group, and 3250 mL and 2450 mL, respectively for the placebo groups. The total blood product use revealed no differences between the two placebo groups (P=NS) nor between the two treatment groups (P=NS). CONCLUSIONS: Tranexamic acid and aprotinin are both effective in reducing intraoperative and postoperative blood loss and the need for blood product transfusion for patients undergoing reoperative cardiac valvular surgery.

A North American survey of intravenous regional anesthesia.

UNLABELLED: One thousand questionnaires concerning the techniques and complications of intravenous regional anesthesia (IVRA) were sent to 900 American and 100 Canadian anesthesiologists. Of the 321 respondents, 86% perform IVRA regularly. A wide variation in device-related and clinical aspects was found, ranging from acceptable to falling outside published guidelines. Anesthesiologists perform a median of four upper-limb IVR procedures per month, most often using 50 mL of lidocaine 0.5% at tourniquet pressures of 250 mm Hg or 100 mm Hg greater than the systolic blood pressure. Forearm, thigh, and calf IVRA are occasionally used. Complications, reported infrequently in the literature, were reported by respondents, including mistaken deflation of the cuff; dysphoria, dizziness, or facial tingling; seizures; cardiac arrests; and deaths. Although there was no correlation between complications and deviation from traditional practice, we recommend that IVRA be performed following recognized protocols by anesthesiologists who are familiar with the technique and trained to treat its potential complications. We recommend a protocol for IVRA. IMPLICATIONS: Intravenous regional anesthesia is a widely used anesthetic technique. A survey of 321 American and Canadian anesthesiologists indicates a wide variation in technique. Despite no correlation between complications and technique, the authors recommend that recognized protocols be used for this technique.

Tranexamic acid reduces blood loss and transfusion in reoperative cardiac surgery.

PURPOSE: The objective of this study was to assess the effect of tranexamic acid (TA), a synthetic antifibrinolytic, on blood loss and the need for transfusion of blood products following repeat cardiac valve surgery. METHODS: After ethics committee approval, 41 patients scheduled for reoperative valve replacement were enrolled in this randomized, double blind, placebo controlled study. Patients were randomized to receive TA (10 g in 500 ml NSaline) or placebo (NSaline) as an iv bolus over 30 min, after anaesthesia induction and prior to skin incision. Intraoperative blood loss was assessed by estimating blood volume on drapes, weighing surgical sponges, and measuring suction bottle returns. Postoperative blood loss was measured from mediastinal chest tube drainage following surgery. Blood products were transfused according to a standardized protocol. RESULTS: Patient demographics were similar for age, sex, cardiopulmonary bypass pump time, cross clamp time, surgical time, preoperative haemoglobin, coagulation profile, and the number of valves replaced during surgery. Tranexamic acid administration reduced intraoperative blood loss [median (range)] from 1656 (575-6270) to 720 ml (355-5616) (P < 0.01) and postoperative blood loss from 1170 (180-4025) to 538 ml (135-1465) (Intent to Treat n = 41, P < 0.01). The total red blood cells transfused (median, range) was reduced from 1500 (0-9300) ml to 480 (0-2850) ml (P < 0.01) in the TA group. In hospital complications and mortality rates were not reduced in the TA group. CONCLUSION: Tranexamic acid reduced blood loss and the need for blood product transfusion and appears to be an effective treatment for patients undergoing reoperative cardiac valvular surgery.

Residual neuromuscular blockade after cardiac surgery: pancuronium vs rocuronium.

PURPOSE: To determine the incidence of residual neuromuscular blockade after cardiac surgery in patients receiving either rocuronium or pancuronium for muscle relaxation. METHODS: In a prospective, controlled, double-blind study, 20 patients undergoing coronary artery bypass were randomized to receive either rocuronium (n = 10) or pancuronium (n = 10) during surgery. Anaesthesia was induced with sufentanil, benzodiazepine and propofol or ketamine, and maintained with air/O2/sufentanil/isoflurane. Neuromuscular blockade was induced with 0.1 ml.kg-1 from blinded syringes containing recuronium (6 mg.ml-1) (Group R) or pancuronium (1 mg.ml-1) (Group P). Relaxants were administered according to clinical criteria and reversal agents were not given. After surgery, neuromuscular transmission was assessed by train-of-four stimulation of the ulnar nerve/adductor pollicis EMG (Datex Relaxograph). Mean values from three trains of stimuli were recorded and repeated 30 min later if TOF ratio was < 0.7. Time to extubation was recorded. RESULTS: On arrival in the ICU, nine of 10 patients in group R but only three of 10 patients in group P demonstrated four visible responses (P < 0.05). Mean TOF ratio in group P, 0.03 +/- 0.05, was less than in group R, 0.68 +/- 0.34 (P < 0.001). All patients in group P and 4 of 10 patients in group R had TOF ratio < 0.7 (P = 0.01). Time to extubation in group P (median 18, range 6-48 hr) was not statistically different from that in group R (14, 5-44 hr). CONCLUSION: Residual neuromuscular block, TOF ratio < 0.7, is common after cardiac surgery but the incidence is less when pancuronium is replaced by rocuronium.

Platelet activating factor and thromboxane B2 production after cardiopulmonary bypass.

Platelet-activating factor (PAF) is believed to have a central role in the pathogenesis of ischemia-reperfusion injury. The purpose of this study was to investigate the relationships among production of PAF, thromboxane B2 (T alpha B2), and cardiopulmonary sequelae in patients undergoing coronary artery bypass graft surgery (CABGS). Venous blood from nine patients (eight men, one woman) undergoing scheduled CABGS, was sampled from central venous catheters before anesthetic induction, pre-cardiopulmonary bypass (CPB), 10 and 30 minutes post-CPB, 10 and 30 minutes post-aortic declamping, and 120 minutes and 24 hours after the conclusion of CPB. Plasma levels of PAF and T alpha B2 were determined by radioimmunoassay kits (Amersham Canada Ltd.). PAF and T alpha B2 were significantly different between high-risk patients (group I; Canadian Cardiovascular Society class 3-4; n = 4) and low-risk patients (group II; Canadian Cardiovascular Society class 2; n = 5): group I PAF = 960 pg/mL, group II PAF = 159 pg/mL (P = 0.0029); group I T alpha B2 = 320 pg/mL, group II T alpha B2 = 229 pg/mL (P = 0.0262). Group I PAF was significantly greater than group II PAF: before CPB = 825 pg/mL (group I), 138 pg/mL (group II); during initiation of CPB = 1600-2015 pg/mL (group I), 158-200 pg/mL (group II) (P = 0.0143). Correlations between duration of CPB and peak PAF (r = 0.7049, P = 0.0339), peak PAF level, and time to extubation (r = 0.8863, P = 0.0079) were significant. PAF levels were different in patients requiring postoperative epinephrine (2124 +/- 700 pg/mL) or dopamine (667 +/- 266 pg/mL) (P = 0.0042). The production of PAF is determined by preoperative patient characteristics and duration of CPB. Increased levels of PAF in patients with unstable angina, left main coronary artery disease, or recent myocardial infarction are associated with the need for increased inotropy and prolonged ventilatory support following CABGS. The degree of PAF production during CPB may be a factor in postoperative instability in high-risk patients.

Small-dose hypobaric lidocaine-fentanyl spinal anesthesia for short duration outpatient laparoscopy. I. A randomized comparison with conventional dose hyperbaric lidocaine.

A randomized, single-blind trial of two spinal anesthetic solutions for outpatient laparoscopy was conducted to compare intraoperative conditions and postoperative recovery. Thirty women (ASA physical status I and II) were assigned to one of two groups. Group I patients received a small-dose hypobaric solution of 1% lidocaine 25 mg made up to 3 mL by the addition of fentanyl 25 micrograms. Group II patients received a conventional-dose hyperbaric solution of 5% lidocaine 75 mg (in 7.5% dextrose) made up to 3 mL by the addition of 1.5 mL 10% dextrose. All patients received 500 mL of crystalloid preloading. Spinal anesthesia was performed at L2-3 or L3-4 with a 27-gauge Quincke point needle. Surgery commenced when the level of sensory anesthesia reached T-6. Intraoperative hypotension requiring treatment with ephedrine occurred in 54% of Group II patients but not in any Group I patients. Median (range) time for full motor recovery was 50 (0-95) min in Group I patients compared to 90 (50-120) min in Group II patients (P = 0.0005). Sensory recovery also occurred faster in Group I patients (100 +/- 22 min) compared with Group II patients (140 +/- 27 min, P = 0.0001). Postoperative headache occurred in 38% of all patients and 70% of these were postural in nature. Oral analgesia was the only treatment required. Spinal anesthesia did not result in a significant incidence of postoperative backache. On follow-up, 96% said they found spinal needle insertion acceptable, 93% found surgery comfortable, and 90% said they would request spinal anesthesia for laparoscopy in future. Overall, this study found spinal anesthesia for outpatient laparoscopy to have high patient acceptance and a comparable complication rate to other studies. The small-dose hypobaric lidocaine-fentanyl technique has advantages over conventional-dose hyperbaric lidocaine of no hypotension and faster recovery.

Small-dose hypobaric lidocaine-fentanyl spinal anesthesia for short duration outpatient laparoscopy. II. Optimal fentanyl dose.

We performed a double-blind, controlled trial to determine the optimal dose of intrathecal fentanyl in small-dose hypobaric lidocaine spinal anesthesia for outpatient laparoscopy. Sixty-four gynecological patients were randomized into three groups, receiving 0, 10, or 25 micrograms fentanyl added to 20 mg lidocaine and sterile water (total 3 mL). Administration was with 27-gauge Whitacre needles and patients sat upright until the block was > T-8. One patient in the 0-microgram fentanyl group required general anesthesia 40 min after the start of surgery, leaving 21 patients per group. Three patients in each of the 0-microgram and 10-microgram fentanyl groups had mild discomfort with trocar insertion, or return of some sensation and felt discomfort or sutures toward the end of surgery. Shoulder-tip pain was less frequent in the 25-microgram than 0-microgram fentanyl group, 28% vs 67% (P < 0.0166). Intraoperative supplementation with alfentanil (+/- propofol) was needed less often in the 25-microgram than 0-microgram fentanyl group, 43% vs 76% (P = 0.028). Recovery of sensation took longer in the 25-microgram than in the 0-microgram and 10-microgram fentanyl groups, 101 +/- 21 vs 84 +/- 20 and 87 +/- 18 min (P < 0.05), although motor recovery and discharge times were the same. Postoperative analgesia was needed earlier in the 0-microgram than in the 25-microgram fentanyl group, median 54 (13-120) vs 87 (65-132) min (P < 0.05). Pruritus was the only side effect that occurred more often in the 10-microgram and 25-microgram groups than in the 0-microgram fentanyl group, 62% and 67% vs 14% (P < 0.0166). One patient required an epidural blood patch for postdural puncture headache. Based on these results, we concluded that 25 micrograms intrathecal fentanyl is required when 20 mg lidocaine is used for hypobaric spinal anesthesia (SA) to ensure reliable, durable anesthesia, reduce shoulder-tip pain, and minimize the need for intraoperative supplementation. This dose provides longer postoperative analgesia and does not increase side effects apart from pruritus. SA with small-dose hypobaric lidocaine-fentanyl was found to be a satisfactory technique for outpatient laparoscopy, although postdural puncture headache can occur in some patients.

Factors involved in the incidence of post-dural puncture headache with the 25 gauge Whitacre needle for obstetric anesthesia.

Parturients have the greatest risk of postdural puncture headache. use of a pencil-point needle, such as the 25 gauge Whitacre, has been associated with a lower incidence of PDPH. This observational study of 1009 obstetrical patients assessed possible factors related to the incidence of PDPH and other complications associated with spinal anesthesia using the 25 gauge Whitacre needle. The independent variables included procedure, maternal position at insertion, ease of insertion, intraoperative i.v. analgesia supplementation, use of intrathecal narcotics, parity and type of local anesthetic. Patients were followed daily during their hospitalization and questioned specifically about the presence of headache, its nature, onset and treatment. Two hundred and twenty-nine patients developed a headache postperatively but only 25 had postdural puncture headaches (overall incidence 2.5%). The PDPH typically presented on day 2 (median), range 1-4). Six patients (0.59%) required epidural blood patch. There were eight (0.8%) failed finals which were converted to general anesthesia. None of the factors evaluated were significant in predicting the occurrence of PDPH.

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

PURPOSE: 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 variable with outcome. METHODS: 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. RESULTS: 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 II 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. CONCLUSION: 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 trial it would have major implications for the use of PRBC in severe sepsis.

Intravenous sedation prior to peribulbar anaesthesia for cataract surgery in elderly patients.

PURPOSE: To investigate if pre-block iv sedation using midazolam, alfentanil, or a midazolam-alfentanil combination minimizes pain, reduces pain recall, and attenuates haemodynamic responses to peribulbar block; and to determine other factors influencing oxygen saturation (SpO2) following iv sedation. METHODS: In a randomized, double-blind, placebo-controlled study, 120 patients, mean age 73 yr, having cataract surgery with peribular anaesthesia, were randomized to receive either normal saline, 1 mg midazolam, 500 micrograms alfentanil, or 0.5 mg midazolam plus 250 micrograms alfentanil. Blood pressure (BP), heart rate (HR) and pulse oximetry readings were recorded before injection of the study drugs, immediately after completion of the peribulbar block, and 10 min after the block. Pain from the anaesthetic block was assessed immediately after the block and after surgery using a visual analog scale, and recall of pain was assessed by telephone on the day after surgery. RESULTS: Pain scores were low in all four groups. Midazolam-alfentanil reduced pain perception, and all iv sedation used reduced pain recall. Midazolam reduced systolic BP; alfentanil +/- midazolam reduced HR. All iv sedation reduced SpO2 more than did saline, but not usually to a clinically important level. Nine patients had a SpO2 < or = 90%; all had received alfentanil with or without midazolam. It was not possible to predict oxygen saturation levels by any factors other than iv sedation and baseline SpO2 levels. CONCLUSION: Intravenous sedation with midazolam or alfentanil or in combination reduced pain perception, pain recall, and haemodynamic responses from peribulbar anaesthesia. Fifteen percent of patients given alfentanil developed clinically important oxygen desaturation. The use of fine gauge needles combined with slow injection of anaesthetic solution causes minimal discomfort, and routine iv sedation may be unnecessary.

On line ST-segment analysis for detection of myocardial ischaemia during and after coronary revascularization.

PURPOSE: A paucity of information exists to validate the accuracy and reliability of ECG monitoring in the operating room or ICU. The purpose of this study was to determine the accuracy, sensitivity, specificity, and predictive values of the Marquette ECG monitor for detection of perioperative myocardial ischaemia (PMI) as measured by ST segment changes in a high risk population. METHODS: Monitoring for PMI in 28 patients scheduled for aortocoronary bypass surgery was done with the Cardiodata PR ambulatory continuous electrocardiography (ACECG) monitor lead V5, and compared with lead V5 of the Marquette Series 7000 ECG/Surgical operating room monitor, and ECG/Resp ICU monitor. The Marquette lead V5 was evaluated using current criteria for the assessment of diagnostic tests including concordance, sensitivity, specificity, positive and negative predictive values, false positive and false negative rates and compared with the ACECG monitor which served as the reference or "gold standard." Agreement beyond chance between the two methods was assessed using the Kappa statistic. RESULTS: Of the 53 observation data points, 27 were defined as ischaemic episodes by ACECG. Concordance between lead V5 in each system was 83% (44/53 episodes). Discordance was 17% (9/53 episodes), predominantly in the postbypass interval (77%, 7/9; P = 0.0184). The incidences of false negatives and false positives for Marquette lead V5 was 26% (7/27) and 7.7% (2/26), respectively. The sensitivity and specificity of the Marquette was 0.74 and 0.92. Positive predictive value was 0.91, negative predictive value was 0.77, and Kappa statistic was 66%. CONCLUSION: Automated ST segment analysis with the Marquette Series 7000 monitoring system demonstrates good diagnostic accuracy, moderate sensitivity, and high specificity. However, clinically significant false negative and false positive rates of ischaemia detection are associated with its use, especially in the postoperative period.

Comparative effects of three doses of intravenous ketorolac or morphine on emesis and analgesia for restorative dental surgery in children.

PURPOSE: The optimal dose of intravenous ketorolac tromethamine (ketorolac), a non-steroidal anti-inflammatory drug has not been determined in children. There are only limited published data on the use of intravenous ketorolac for paediatric analgesia. This study compares the analgesic and emetic effect of three different doses of ketorolac with morphine in paediatric dental surgical out-patients. METHODS: Following institutional approval and parental consent, 120 ASA I or II children, age 2-10 yr were randomized to four groups and received ketorolac 0.75, 1.0, and 1.5 mg.kg-1 or morphine 0.1 mg.kg-1 iv at induction of a standardized anaesthetic. At 15 and 30 min after arrival in the recovery room a blinded observer assessed pain using the Objective Pain Score (OPS). Twenty-four hours after surgery a telephone interview was carried out with a parent at home. RESULTS: There were no differences in demographic data, anaesthesia time, recovery and day-care unit time, OPS and postoperative analgesic requirements in the four groups. Postoperative vomiting in the first 24 hr occurred more frequently in the morphine group than in the other groups (P < 0.0166). No patient had excessive surgical bleeding. CONCLUSIONS: Ketorolac, in all doses studied (0.75, 1.0 and 1.5 mg.kg-1) was as effective an analgesic as morphine 0.1 mg.kg-1 given intravenously at induction to children having restorative dental surgery. Its use was associated with a significant reduction in the incidence of postoperative vomiting.