Induced preconditioning of cardiac performance in coronary bypass surgery--sevoflurane vs propofol.

UNLABELLED: Twenty ASA III and IV adult patients scheduled for elective coronary artery surgery were included in the study. Anesthesia was induced and maintained with either sevoflurane (sevoflurane group; n = 10) or propofol (propofol group; n = 10). All preoperative cardiac medications were continued until the morning of surgery. There were significant decreases in mean arterial blood pressure, cardiac index and ejection fraction after CPB in propofol group compared with sevoflurane. Further, the plasma creatine kinase myocardial isoenzyme concentrations were significantly higher in propofol group but did not approach the critical values needed for diagnosis of myocardial infarction. CONCLUSION: It is concluded that, sevoflurane appears to be associated with better hemodynamic stability before and after CPB than propofol. This could be attributed to cardioprotective effect of sevoflurane during ischemia and reperfusion.

Traumatic aortic pseudoaneurysm.

A case report of a 5 years old male child, with a history of crash injury--(blunt trauma)--on the chest. Computed tomography (CT) scan, magnetic resonance imaging (MRI) of the chest revealed an aneurysm involving the arch of the aorta. An aortogram showed its exact extension. Chest X-Ray showed collapsed left lung (due to pressure of aneurysm on left main bronchus). Surgery was done o aortic arch: Resection of the aneurysm, and patch repair of aorta, under profound hypothermic circulatory arrest (PHCA) and CPB. Left bronchial tear was also closed. Post operatively the patient was ventilated for about 36 hours to allow for lung expansion. The patient had a smooth postoperative course. Intensive chest physiotherapy and repeated bronchoscopies helped in recovering the left lung function.

The use of low-dose rocuronium to facilitate laryngeal mask airway insertion.

In this two-phase study, the efficacy of low-dose rocuronium to facilitate laryngeal mask airway (LMA) insertion was evaluated. First, the onset time of 100, 150 and 300 micrograms.kg-1 rocuronium was determined using mechanomyography in three groups of patients (n = 10 in each) anaesthetized with propofol-fentanyl-nitrous oxide. In the second part, 100, 150 or 300 micrograms.kg-1 rocuronium or placebo was administered randomly to four groups of patients (n = 50 in each) in a double-blind manner. Following this, anaesthesia was induced with propofol 2.5 mg.kg-1. Patients in the group of 300 micrograms.kg-1 rocuronium or placebo received propofol after 1.5 min. Patients in the group of 100 or 150 micrograms.kg-1 rocuronium received propofol after 3 min. The LMA was inserted 90 sec later. Immediately before the induction of anaesthesia, patients were questioned about the symptoms of neuromuscular block. In phase 1, onset times were 180 sec (SD 41), 191 sec (59) and 89 sec (34), respectively. In phase 2, insertion of the LMA was graded as easy in 90.6% of patients receiving rocuronium, compared with 42% of patients who had only propofol (P < 0.05). Rocuronium improved the overall ease of LMA insertion. LMA insertion was graded easy in 80% of patients who received 100 micrograms.kg-1 rocuronium. The incidence of unpleasant effects was greatest with 300 micrograms.kg-1 rocuronium. The optimal dose needed to facilitate LMA insertion with minimal unpleasant effects appeared to be 100 micrograms.kg-1 rocuronium.

Wound closure tramadol administration has a short-lived analgesic effect.

PURPOSE: To evaluate the effects of tramadol administration at wound closure on postoperative pain and analgesic requirements in patients undergoing laparoscopic cholecystectomy. METHODS: In a prospective, randomized, double-blind study 80 patients were allocated into two groups (n = 40 in each) to receive either 200 mg tramadol or placebo i.v. at the time of wound closure. Postoperatively, all patients received tramadol from a patient-controlled analgesia (PCA) device. Pain, analgesic consumption, vital signs and side effects were recorded postoperatively for 24 hr. RESULTS: Administration of 200 mg tramadol at the time of wound closure was associated with a short-lived (60 min) reduction in pain scores and PCA consumption compared with placebo. Although the time to first request for analgesia after surgery was longer in patients who received tramadol at wound closure, there was no difference between the two groups with respect to pain scores or to the requirements of postoperative analgesia over the next 23 hr. The cumulative PCA consumption of tramadol in 24 hr was 139.4+/-108 and 102.4+/-106 mg in the placebo and tramadol groups, respectively (P = 0.06). CONCLUSIONS: Wound closure administration of 200 mg tramadol had a short-lived (60 min) analgesic effect but did not affect the long-term pain scores or analgesic requirements after laparoscopic cholecystectomy.

The comparative dose-response effects of melatonin and midazolam for premedication of adult patients: a double-blinded, placebo-controlled study.

UNLABELLED: We designed this prospective, randomized, double-blinded, placebo-controlled study to compare the perioperative effects of different doses of melatonin and midazolam. Doses of 0.05, 0.1, or 0. 2 mg/kg sublingual midazolam or melatonin or placebo were given to 84 women, approximately 100 min before a standard anesthetic. Sedation, anxiety, and orientation were quantified before, 10, 30, 60, and 90 min after premedication, and 15, 30, 60, and 90 min after admission to the recovery room. Psychomotor performance of the patient was evaluated at these times also, by using the digit-symbol substitution test and Trieger dot test. Patients who received premedication with either midazolam or melatonin had a significant decrease in anxiety levels and increase in levels of sedation preoperatively compared with control subjects. Patients in the three midazolam groups experienced significant psychomotor impairment in the preoperative period compared with melatonin or placebo. After operation, patients who received 0.2 mg/kg midazolam premedication had increased levels of sedation at 90 min compared with 0.05 and 0. 1 mg/kg melatonin groups. In addition, patients in the three midazolam groups had impairment of performance on the digit-symbol substitution test at all times compared with the 0.05 mg/kg melatonin group. Premedication with 0.05 mg/kg melatonin was associated with preoperative anxiolysis and sedation without impairment of cognitive and psychomotor skills or affecting the quality of recovery. IMPLICATIONS: Premedication with 0.05 mg/kg melatonin was associated with preoperative anxiolysis and sedation without impairment of cognitive and psychomotor skills or affecting the quality of recovery.

Spontaneous chylothorax--case report.

A-19-year old male patient complained of shortness of breath. Aspiration of the pleural fluid revealed chylothorax. Right chest tube was inserted. His ABG showed hypoxaemia with relative hypercarbia. He underwent right thoracotomy and thoracic duct ligation under general anaesthesia and double lumen endobroncheal intubation. During surgery he lost 1.5 L of blood and 4 L chyle. He was transferred to the SICU intubated and on mechanical ventilation. On the subsequent days chyle leak was reduced to a minimum of 10 ml/hr. On the 9th postoperative day the patient was extubated. He was receiving TPN 2600 kcal/day. He was transferred to the normal floor on the 15th day. After 7 day he was readmitted, his chest showed severe lung fibrosis and consolidation. His ABG showed severe hypercarbia (PaCO2 = 126 mmHg). The patient was intubated. His condition deteriorated and he was considered for lung transplantation. No donor was available. Later he arrested and died. Anaesthesia and surgical management of spontaneous chylothorax is challenging. The mortality rate is high.

Premedication with melatonin: a double-blind, placebo-controlled comparison with midazolam.

We have evaluated the perioperative effects of melatonin with those of midazolam in 75 women in a prospective, randomized, double-blind, placebo-controlled study. Patients were given sublingual midazolam 15 mg, melatonin 5 mg or placebo, approximately 100 min before a standard anaesthetic. Sedation, anxiety and orientation were quantified before, and 10, 30, 60 and 90 min after premedication, and 15, 30, 60 and 90 min after admission to the recovery room. Psychomotor performance was evaluated at these times also, using the digit-symbol substitution test (DSST) and the Trieger dot test (TDT). Patients who received premedication with either midazolam or melatonin had a significant decrease in anxiety levels and increase in levels of sedation before operation compared with controls. Midazolam produced the highest scores for sedation at 30 and 60 min after administration and significant psychomotor impairment in the preoperative period compared with melatonin or placebo. After operation, patients who received midazolam or melatonin premedication had increased levels of sedation at 30 min and impairment in performance on the DSST at 15, 30 and 90 min compared with controls. There were no significant differences between the three groups for anxiety levels or TDT performance after operation. Amnesia was notable only in the midazolam group for one preoperative event (entry into the operating room). Patient satisfaction was noted in the midazolam and melatonin groups only. We have demonstrated that melatonin can be used effectively for premedication of adult patients.

Death within 24 hours of anesthesia is not always an anesthetic death.

PURPOSE: We report an anesthetic death of a young lady after uneventful anesthetics. CLINICAL FEATURES: A 25-year-old female who had undergone emergency incision and drainage of an abscess in her right breast. Her condition, however, deteriorated few hours after anesthesia and died in less than 24 hours from causes unrelated to anesthesia. The computerized tomography (CT) scan showed a large meningioma in frontal lobe. CONCLUSION: This case illustrates that the risks of anesthesia are increased significantly in patients with silent meningionmas.

Predictive models for difficult laryngoscopy and intubation. A clinical, radiologic and three-dimensional computer imaging study.

PURPOSE: To identify the variables most useful in predicting difficult laryngoscopy and intubation from various clinical, skeletal (lateral x-rays) and soft tissue (three-dimensional computed tomography imaging) measurements. METHODS: Twenty-four adult patients in whom an unanticipated difficult tracheal intubation was identified according to established criteria were evaluated. Further, a control group of 32 patients in whom tracheal intubation was easily accomplished was studied. We applied multivariate discriminant analysis to clinical and radiological data of all patients to select those variables most useful in predicting difficult laryngoscopy and intubation. The receiver operating characteristic (ROC) curve was used to describe the discrimination abilities and to explore the trade-offs between sensitivity and specificity of the model. RESULTS: With the clinical data alone, discriminant analysis identified four risk factors that correlated with the prediction of difficult laryngoscopy and intubation: thyrosternal distance, thyromental distance, neck circumference and Mallampati classification. With both clinical and radiological data, discriminant analysis identified five risk factors: thyrosternal distance, thyromental distance, Mallampati classification, depth of spine C2 and angle A (the most antero-inferior point of the upper central incisor tooth). The positive predictive value of this combined (clinical and radiological) model was greater than that of the clinical model alone (95.8% vs 87.5%, respectively). The areas under the ROC curves, that measure the probability of the correct prediction of the clinical and the combined models, were found to be 0.933 and 0.973, respectively. CONCLUSIONS: These models can be used for predicting difficult laryngoscopy and intubation in clinical practice.

HELLP syndrome: undiagnosed in a case of impending rupture of uterus. A case report.

A 31-year-old women, 34 weeks gestation with intrauterine fetal death, and transverse lie with impending rupture of the uterus due to obstructed labor, was scheduled for urgent cesarean section. On preoperative anesthetic assessment, she was diagnosed to have HELLP syndrome based on clinical findings (subsequently confirmed by laboratory results). She was anesthetized taking the necessary precautions. Her intra and postoperative course is described. The case demonstrates how the anesthetist is often confronted by undiagnosed HELLP syndrome for urgent cesarean section and has limited time for investigations. He should depend on his clinical acumen to diagnose and treat appropriately for a favorable maternal outcome.

Comparative clinical pharmacology of rocuronium, cisatracurium, and their combination.

BACKGROUND: The comparative clinical pharmacology of cisatracurium and rocuronium and their combinations has not been reported. In this study, the authors compared the relative potency and the clinical profile and characterized the interaction of both drugs. METHODS: Two hundred twenty adults classified as American Society of Anesthesiologists physical status I and anesthetized with propofol-fentanyl-nitrous oxide were studied. In part 1, the neuromuscular-blocking effects of cisatracurium and rocuronium were assessed after administration of bolus doses of 20-50 microg/kg and 100-300 microg/kg, respectively. In part 2, we compared the time course of 1xED50, 1, 1.5, and 2xED95 doses of both drugs (where ED50 and ED95 are, respectively, the doses producing 50% and 95% depression of the first twitch height [T1]). In part 3, equieffective combinations of both drugs were studied to characterize their interaction. RESULTS: The calculated ED50 values and their 95% confidence intervals were 111 (107-115) and 26.2 (25.8-26.5) microg/kg [corrected] for rocuronium and cisatracurium, respectively. Compared with equipotent doses of cisatracurium, rocuronium had a faster onset, and a faster spontaneous T1 and train-of-four recovery times that were significant except at maximum recovery with the 2xED95 dose. The interaction between rocuronium and cisatracurium was synergistic, and the time profile of the combination group was different from that of the single-dose groups. CONCLUSIONS: Cisatracurium is four to five times more potent than rocuronium. Rocuronium had a faster onset of action, a shorter clinical duration, and a faster spontaneous recovery rate compared with equipotent doses of cisatracurium.

Adverse effects and drug interactions associated with local and regional anaesthesia.

Systemic and localised adverse effects of local anaesthetic drugs usually occur because of excessive dosage, rapid absorption or inadvertent intravascular injection. Small children are more prone than adults to methaemoglobinaemia, and the combination of sulfonamides and prilocaine, even when correctly administered, should be avoided in this age group. The incidence of true allergy to local anaesthetics is rare. All local anaesthetics can cause CNS toxicity and cardiovascular toxicity if their plasma concentrations are increased by accidental intravenous injection or an absolute overdose. Excitation of the CNS may be manifested by numbness of the tongue and perioral area, and restlessness, which may progress to seizures, respiratory failure and coma. Bupivacaine is the local anaesthetic most frequently associated with seizures. Treatment of CNS toxicity includes maintaining adequate ventilation and oxygenation, and controlling seizures with the administration of thiopental sodium or benzodiazepines. Cardiovascular toxicity generally begins after signs of CNS toxicity have occurred. Bupivacaine and etidocaine appear to be more cardiotoxic than most other commonly used local anaesthetics. Sudden onset of profound bradycardia and asystole during neuraxial blockade is of great concern and the mechanism(s) remains largely unknown. Treatment of cardiovascular toxicity depends on the severity of effects. Cardiac arrest caused by local anaesthetics should be treated with cardiopulmonary resuscitation procedures, but bupivacaine-induced dysrhythmias may be refractory to treatment. Many recent reports of permanent neurological complications involved patients who had received continuous spinal anaesthesia through a microcatheter. Injection of local anaesthetic through microcatheters and possibly small-gauge spinal needles results in poor CSF mixing and accumulation of high concentrations of local anaesthetic in the areas of the lumbosacral nerve roots. In contrast to bupivacaine, the hyperbaric lidocaine (lignocaine) formulation carries a substantial risk of neurotoxicity when given intrathecally. Drugs altering plasma cholinesterase activity have the potential to decrease hydrolysis of ester-type local anaesthetics. Drugs inhibiting hepatic microsomal enzymes, such as cimetidine, may allow the accumulation of unexpectedly high (possibly toxic) blood concentrations of lidocaine. Reduction of hepatic blood flow by drugs or hypotension will decrease the hepatic clearance of amide local anaesthetics. Special caution must be exercised in patients taking digoxin, calcium antagonists and/or beta-blockers.

Awake removal of the laryngeal mask airway is safe in paediatric patients.

PURPOSE: It has been suggested that it is safer to remove the Laryngeal Mask Airway (LMA) in paediatric patients when they are deeply anaesthetised than when they are awake. However, the evidence regarding this recommendation is contradictory. The purpose of the study was to compare the incidence of complications (laryngeal spasm, bronchospasm, coughing, retching, excessive salivation and oxygen desaturation) associated with removal of the LMA in children. METHODS: In a randomised study, we studied 165 ASA physical status I infants and children of both sexes, aged 2 mo to 13 yr. All patients were undergoing elective lower limb or perineal surgery. They were randomly assigned to two groups: in 83 the laryngeal mask was removed when recovery of airway reflexes had been demonstrated and the patients had opened their eyes or mouth in the recovery area. In the other 82 patients it was removed with the patient deeply anaesthetised. RESULTS: Two (2.4%) patients developed laryngeal spasm in the anaesthetised group, one patient (1.2%) desaturated and another vomited (1.2%) in the awake group. CONCLUSION: There was no difference in the incidence of airway complications whether the LMA was removed in the anaesthetised or the awake child.

Response to atracurium and mivacurium in a patient with Charcot-Marie-Tooth disease.

PURPOSE: We studied the neuromuscular effects of both atracurium and mivacurium in a patient with Charcot-Marie-Tooth disease (CMTD) during nitrous oxide-oxygen-alfentanil-propofol anaesthesia. Neuromuscular blockade was monitored electromyographically. Train-of-four stimulation (2 Hz @ 20 sec intervals) was delivered to the ulnar nerve throughout the period of observation. CLINICAL FEATURES: A 17-yr-old man with the diagnosis of CMTD was presented twice for two different orthopaedic surgical procedures. The CMTD had been diagnosed since childhood. Neurological examination revealed distal wasting of the upper and lower limbs, generalised absence of reflexes and decreased sensation in a stocking distribution. In both anaesthetics, induction was carried out with alfentanil and propofol, and anaesthesia was maintained with nitrous oxide in oxygen, alfentanil and propofol infusion. The patient demonstrated a normal response to both atracurium and mivacurium. Onset time and the maximum block attained after atracurium and mivacurium were 240 and 210 sec, and 97% and 99% inhibition of T1 (the first twitch of TOF stimulation), respectively. Recovery of T1 to 10% of the control value occurred 30 and 11.5 min after the administration of atracurium and mivacurium, respectively. The patient made uneventful recoveries after both anaesthetics. CONCLUSION: There was no evidence of prolonged response to atracurium and mivacurium in our patient with CMTD.

Perioperative antinociceptive effects of tramadol. A prospective, randomized, double-blind comparison with morphine.

PURPOSE: To compare the efficacy of tramadol and morphine for intra- and postoperative analgesia in patients undergoing laparoscopic cholecystectomy. METHODS: In a prospective, randomized, double-blind study 100 patients were allocated randomly into two groups. Ten minutes before induction of anaesthesia, patients in group 1 received 100 mg tramadol and those in group 2 received 10 mg morphine i.v. Anaesthesia was induced with 5 mg.kg-1 thiopental and was maintained with O2, N2O plus isoflurane with additional doses of tramadol or morphine as decided by the attending anaesthetist. Postoperatively, patients in group 1 and group 2 received tramadol and morphine, respectively, from a patient-controlled analgesia (PCA) device. Pain, analgesic consumption, vital signs and side effects were recorded postoperatively for 24 hr. RESULTS: Intraoperative consumption of tramadol and morphine were 137 +/- 37 and 12.2 +/- 3 mg, respectively. Compared with morphine, patients receiving tramadol had higher blood pressures and required greater mean ETisQ to control haemodynamic variables (P < 0.05). Postoperatively, there were no differences in observer pain score or visual analogue pain score during the first 24 hr between groups except at 30, 45, and 90 min where patients in the tramadol group reported higher pain scores (P < 0.05). The cumulative, 24 hr PCA consumption was 111 +/- 93 and 7.5 +/- 6.6 mg of tramadol and morphine, respectively. CONCLUSIONS: There was no difference between the use of tramadol and morphine to treat pain after laparoscopic cholecystectomy from 90 min after the end of surgery. Morphine was more effective than tramadol as an intraoperative analgesic.