Negative pressure ventilation vs. spontaneous assisted ventilation during rigid bronchoscopy: A controlled randomised trial

Background: Ventilation during interventional rigid bronchoscopy (IRB) under general anaesthesia (jet ventilation, positive pressure ventilation and spontaneous assisted ventilation) may offer some difficulties. This study compares the effectiveness during IRB of intermittent negative pressure ventilation (INPV) and spontaneous assisted ventilation (SAV). Methods: Thirty-eight patients submitted to IRB were randomised into two groups: SAV or INPV. All patients received a total intravenous anaesthesia; INPV patients were paralysed. Pre-and intra-operative arterial blood gases and O₂ flow through a rigid bronchoscope were assessed. The endoscopist applying a subjective score evaluated the operating conditions. Results: Patients of the INPV group, as compared to the SAV group, required a lower dosage of fentanyl (2.6 ± 1.8 (μg · kg^?1· h^?1 vs. 6.6 ± 4.8 μg · kg^?1· h^?1), a lower O₂ supply (3.3 ± 2.8 1/min vs. 11.6 ± 3.4 1/min), a shorter recovery time (5.4 ± 2.9 min vs. 9.8 ± 7.1 min) and no manually assisted ventilation (0 ± 0 vs. 1 ± 1.1 nd?/procedure). Intraoperative PaCO₂ was higher in the SAV (8.1 ± 1.3 kPa) than in the INPV group (5.0 ± 1.6 kPa) and intraoperative pH differed in the two groups (7.26 ± 0.05, SAV vs. 7.47 ± 0.08, INPV). Operating conditions, as assessed by a subjective score, were considered better with INPV than with SAV (4.9 vs. 4.3). Conclusions: As compared to SAV, INPV in paralysed patients during IRB reduces administration of opioids, shortens recovery time, prevents respiratory acidosis, excludes the need for manually assisted ventilation, reduces 02 need and affords optimal surgical conditions. INPV appears a safe, non-invasive and effective ventilatory management during IRB.     

The effects of remifentanil on haemodynamic stability during rigid bronchoscopy

We examined the effect of remifentanil on the haemodynamic response to rigid bronchoscopy in 22 adult ASA 2-4 patients, randomly allocated to receive 1.0 microg.kg-1 remifentanil over 1 min followed by 0.5 microg.kg-1.min-1 (remifentanil group) or 2.0 microg.kg-1 fentanyl followed by a saline infusion (control group). Following the initial infusion, all patients received a sleep dose of propofol followed by rocuronium 0.6 mg.kg-1 and their lungs were ventilated using a Sander's injector attached to the rigid bronchoscope. Direct arterial blood pressures, heart rate and ST segment changes on the CM5 lead configuration of the electrocardiograph were measured at 1-min intervals from before induction of anaesthesia until the end of bronchoscopy. Arterial pressures and heart rate were similar in the two groups before and after induction of anaesthesia. Remifentanil attenuated the haemodynamic response to bronchoscopy (p < 0.05 for increases in arterial pressures and heart rate). Four patients in the remifentanil group had ST segment depression compared with eight patients in the control group, but this was not statistically significant.     

A comparison of remifentanil and fentanyl in patients undergoing carotid endarterectomy

BACKGROUND AND AIM: We investigated the haemodynamic stability and emergence characteristics of isoflurane/nitrous oxide anaesthesia supplemented with remifentanil or fentanyl in patients undergoing carotid endarterectomy. METHODS: Anaesthesia was induced with propofol (1-2 mg kg-1) and either remifentanil (0.5 microgram kg-1) or fentanyl (1 microgram kg-1), followed by an infusion of remifentanil (0.2 microgram kg-1 min-1) or fentanyl (2 micrograms kg-1 h-1). RESULTS: There were no significant differences between the groups in haemodynamic variables, postoperative pain, nausea or vomiting. After induction there was a significant decrease in mean arterial pressure for both groups (P < 0.001) and a decrease in heart rate (P = 0.001) in the remifentanil group. In both groups these haemodynamic changes continued during maintenance of anaesthesia (P < 0.05). The time to eye opening after surgery was significantly shorter with remifentanil compared with fentanyl (6.62 +/- 3.89 vs. 18.0 +/- 15.18 min, P = 0.015). CONCLUSION: Remifentanil appears to be a comparable opioid to fentanyl when supplementing isoflurane/nitrous oxide anaesthesia for carotid endarterectomy.     

Anaesthesia for ultrasound guided oocyte retrieval: midazolam/remifentanil versus propofol/fentanyl regimens

To evaluate the quality of intra-operative anaesthesia and recovery characteristics of two different anaesthesia regimens, 60 healthy women undergoing ultrasound guided oocyte retrieval for in vitro fertilization procedures were randomly allocated to receive either a propofol/fentanyl or a midazolam/remifentanil based anaesthesia. The surgical procedure was successful in all patients and no severe side effects were reported by any patient. Four patients in the midazolam/remifentanil group (13%) would not accept the same anaesthetic procedure for further in vitro fertilization treatment due to intra-operative awareness, while all propofol/fentanyl patients were prepared to accept the same procedure again (P < 0.05). Patients in the propofol/fentanyl group required manual ventilation more frequently through a facemask than those patients treated with the midazolam/remifentanil combination (50% and 30%, respectively; P < 0.05). The time to achieve an Aldrete's score of 10 was shorter in the midazolam/remifentanil patients (2 +/- 2 min) than in those who received propofol/fentanyl (4 +/- 2 min) (P < 0.001), but no differences were observed in the time required to be 'fit to discharge' from the post-anaesthesia care unit. We conclude that the use of a midazolam/remifentanil regimen is as effective and safe as a fentanyl/propofol regimen in patients undergoing transvaginal oocyte retrieval for in vitro fertilization procedures.     

Anesthesia with sevoflurane and remifentanil under spontaneous respiration assisted with high‐frequency jet ventilation for tracheobronchial foreign body removal in 586 children

Background: Foreign body aspiration is a common life‐threatening event in young children. Tracheobronchial foreign body removal is usually performed by rigid tracheobronchoscopy under general anesthesia. Anesthetic and ventilation techniques vary greatly among anesthesiologists and institutions. In the present retrospective study, we report our anesthetic experience over 5 years. We describe complications and outcomes and analyze the clinical characteristics of anesthesia and ventilation. Methods: We retrospectively reviewed relevant clinical findings of 586 pediatric patients treated with rigid tracheobronchoscopy under general anesthesia. All procedures were performed under inhaled sevoflurane anesthesia combined with remifentanil infusion, with spontaneous respiration assisted by high‐frequency jet ventilation (HFJV) and topical airway anesthesia. Results: Among 586 patients, the foreign body was successfully removed by rigid tracheobronchoscopy in 558 patients, and no foreign body was found in 28 patients. Laryngospasm was observed during the procedure in five patients. Hypoxemia was observed in 15 patients (2.6%). No severe complications or deaths occurred. The mean operation time was 22 min and the average hospital stay was 2 days. Conclusion: Inhaled sevoflurane anesthesia combined with remifentanil infusion, with spontaneous respiration assisted by HFJV and topical airway anesthesia, is safe and effective for tracheobronchial foreign body removal.     

A randomized trial of caudal block with bupivacaine 4 mg x kg-1 (1.8 ml x kg-1) plus morphine (150 microg x kg-1) vs general anaesthesia with fentanyl for cardiac surgery

BACKGROUND: Regional anaesthesia has been used effectively in paediatric patients undergoing cardiac surgery and is thought to be safe. METHODS: Thirty patients ASA physical status II-III undergoing scheduled palliative or corrective cardiac surgery, receiving premedication with midazolam and anaesthetic induction with sevoflurane, fentanyl and pancuronium were randomly allocated to two groups. In group 1, patients received bupivacaine 0.22% 4 mg.kg-1 (1.8 ml.kg-1) and morphine 150 microg x kg-1 by the caudal route. After a 20-min period for the block to take effect, sevoflurane 0.5-1.0% and fentanyl 5 microg x kg-1 were administered for maintenance of anaesthesia. In group 2, the anaesthetic technique was the same as in group 1, without a caudal block and fentanyl 25 microg x kg-1 was administered at the moment of surgical incision. RESULTS: Cardiovascular and haemodynamic responses of patients receiving caudal block showed minor variations during the 20-min period between caudal and general anaesthesia. Fentanyl requirements during surgery were lower (P = 0.001) in patients with caudal block than patients with general anaesthesia. Extubation time was shorter (P = 0.034) in the caudal group. Two patients in the general anaesthesia group and one in the caudal group died because of postoperative complications. CONCLUSIONS: Caudal block with bupivacaine 0.22% 4 mg.kg-1 (1.8 ml.kg-1) and morphine 150 microg x kg-1 was safe and effective for paediatric patients undergoing cardiac surgery. However, patients might have a better outcome with a reduction of morphine dosage and administration of a muscle relaxant of shorter duration of action than pancuronium.     

Effects of remifentanil and fentanyl on intraocular pressure during the maintenance and recovery of anaesthesia in patients undergoing non-ophthalmic surgery

BACKGROUND AND OBJECTIVE: To compare the effects of remifentanil and fentanyl on intraocular pressure during the maintenance and recovery of anaesthesia in patients undergoing elective non-ophthalmic surgery. METHODS: Thirty-two patients (ASA I-II) were randomized into two groups to receive either a continuous infusion of remifentanil (0.25-0.5 microg kg(-1) min(-1), n =16, Group R) or an intermittent bolus of fentanyl (2-5 microg kg(-1), n = 16, Group F) during the maintenance of anaesthesia. For the induction of anaesthesia, Group R received remifentanil 1 microg kg(-1) and Group F received fentanyl 2 microg kg(-1); both groups then received propofol 2 mg kg(-1) with vecuronium 0.1 mg kg(-1). Anaesthesia in both groups was maintained with a continuous infusion of propofol 4-8 mg kg(-1) h(-1). Ventilation of the lungs was controlled to a constant end-tidal PCO2 of 4.7-5.4 kPa. Blood pressure, electrocardiography, heart rate and oxygen saturation were monitored throughout anaesthesia. Intraocular pressure was determined before surgery, during the maintenance of anaesthesia, 2 min after emergence and in the recovery room using a Perkins hand-held applanation tonometer by an ophthalmologist blinded to the anaesthetic technique. RESULTS: After induction of anaesthesia, a significant decrease in intraocular pressure in the remifentanil group from 13.6 +/- 2.6 to 7.1 +/- 3.1 mmHg (P < 0.001) and in the fentanyl group from 13.7 +/- 2.2 to 9.7 +/- 3.4 mmHg (P < 0.001) was observed and maintained during anaesthesia. Thirty minutes after the end of anaesthesia, intraocular pressure returned to baseline values in both groups (remifentanil: 13.9 +/- 2.8 mmHg, P = 0.28; fentanyl: 13.6 +/- 2.3 mmHg, P = 0.59). The intraocular pressure and haemodynamic variables did not differ significantly between the two groups (intraocular pressure, P = 0.7327; blood pressure, P = 0.1295; heart rate, P = 0.8601). CONCLUSIONS: Remifentanil maintains intraocular pressure at an equally reduced level compared with fentanyl.     

Cerebral blood flow velocity and carbon dioxide vasoreactivity during gamma-hydroxybutyrate/fentanyl anaesthesia in non-neurosurgical patients

In this study the effects of gamma-hydroxybutyrate/fentanyl on cerebral blood flow velocity (CBFV) (as measured in the middle cerebral artery by transcranial Doppler ultrasonography) and on cerebrovascular carbon dioxide reactivity were investigated. Mean CBFV (Vmean) and haemodynamic responses were recorded in 12 non-neurosurgical patients before, during and after induction of general anaesthesia with gamma-hydroxybutyrate (GHB) (20 min constant rate infusion of 100 mg kg-1). Two patients were excluded, one because of bradycardia and the other because of severe myoclonia. During the infusion of GHB, normocapnia was maintained by manually assisting ventilation as necessary. The infusion of GHB did not affect Vmean [awake: 57 +/- 12 cm s-1 (mean +/- SD); 22.5 min: 62 +/- 15 cm s-1, NS difference] or mean arterial blood pressure (MAP) (awake: 97 +/- 12 mmHg; 22.5 min: 89 +/- 10 mmHg, NS). This suggests that cerebral blood flow velocity is unaltered by an anaesthetic dose of GHB. Twenty-five minutes after the start of GHB, fentanyl 3 micrograms kg-1 and vecuronium 0.1 mg kg-1 were given, the trachea was intubated and the lungs were mechanically ventilated to maintain end-tidal PCO2 of 4.6 +/- 0.4 kPa (30 min). At 30 min after the start of the GHB infusion, Vmean and MAP decreased to 38 +/- 10 cm s-1 and 76 +/- 12 mmHg (both P < 0.05 vs 22.5 min) respectively. After adjusting the ventilation to achieve hypocapnia (40 min: end-tidal PCO2 3.5 +/- 0.2 mmHg), Vmean decreased to 29 +/- 7 cm s-1, while MAP did not change. This allowed the relative vasoreactivity (percentage change in Vmean/0.133 kPa change in the end-tidal PCO2 from normocapnia to hypocapnia) to be estimated as 2.7 +/- 1.6% 0.133 kPa-1. This suggests that cerebrovascular response to CO2 during gamma-hydroxybutyrate/fentanyl anaesthesia is maintained.     

Intra- and post-operative blood loss and haemodynamics in total hip replacement when performed under lumbar epidural versus general anaesthesia

The effects of lumbar epidural anaesthesia and two types of general anaesthesia on blood loss and haemodynamics during and after hip replacement were compared in three groups of patients. One group (n = 14) received continuous lumbar epidural anaesthesia, another group (n = 10) was given inhalational anaesthesia and spontaneous breathing after endotracheal intubation, and the third group (n = 14) received artificial ventilation after intubation and pancuronium and fentanyl intermittently i.v. Intra-operative blood loss in patients under epidural anaesthesia was 950 +/- 300 ml (mean +/- SD) and blood loss during the following 24 h-i.e. as long as the epidural anaesthesia was maintained-was 370 +/- 80 ml. These figures were significantly lower than the intra- and post-operative blood losses in patients under general anaesthesia with narcotics as post-operative pain treatment: 1140 +/- 200 ml (inhalational anaesthesia) followed by 480 +/- 70 ml and 1540 +/- 340 ml (artificial ventilation) followed by 500 +/- 110 ml. The intra-operative blood loss in the general anaesthesia group with spontaneous breathing was significantly smaller than the blood loss in the artificially ventilated group, whereas the post-operative blood loss in the two general anaesthetic groups was similar. Haemodynamic differences explain these differences in blood loss. Thus epidural anaesthesia induced hypotension on the arterial and venous sides. Intra-operatively, inhalational anaesthesia also induced hypotension on the arterial and venous sides compared with general anaesthesia using artificial ventilation. Post-operatively, the general anaesthesia groups behaved haemodynamically similarly and no differences in blood loss were seen. The reduction in blood loss, notably associated with lumbar epidural anaesthesia, is beneficial in decreasing the hazard and cost of blood transfusion.     

Anesthesia for removal of inhaled foreign bodies in children

BACKGROUND: Foreign body aspiration may be a life-threatening emergency in children requiring immediate bronchoscopy under general anesthesia. Both controlled and spontaneous ventilation techniques have been used during anesthesia for bronchoscopic foreign body removal. There is no prospective study in the literature comparing these two techniques. This prospective randomized clinical trial was undertaken to compare spontaneous and controlled ventilation during anesthesia for removal of inhaled foreign bodies in children. METHODS: Thirty-six children posted for rigid bronchoscopy for removal of airway foreign bodies over a period of 2 years and 2 months in our institution were studied. After induction with sleep dose of thiopentone or halothane, they were randomly allocated to one of the two groups. In group I, 17 children were ventilated after obtaining paralysis with suxamethonium. In group II, 19 children were breathing halothane spontaneously in 100% oxygen. RESULTS: All the patients in the spontaneous ventilation group had to be converted to assisted ventilation because of either desaturation or inadequate depth of anesthesia. There was a significantly higher incidence of coughing and bucking in the spontaneous ventilation group compared with the controlled ventilation group (P = 0.0012). CONCLUSION: Use of controlled ventilation with muscle relaxants and inhalation anesthesia provides an even and adequate depth of anesthesia for rigid bronchoscopy.     

Acute respiratory acidosis does not increase plasma potassium in normokalaemic anaesthetized patients. A controlled randomized trial.

BACKGROUND AND OBJECTIVE: Few and conflicting data are available regarding the changes of plasma potassium concentration during acute respiratory acidosis in human beings. This study compares the acute changes in plasma potassium concentration in acutely hypercapnic patients and in non-hypercapnic patients during general anaesthesia. METHODS: Thirty-three patients undergoing interventional rigid bronchoscopy were studied. Ventilation of the lungs was randomly conducted using either spontaneous-assisted ventilation or intermittent negative-pressure ventilation. All patients received the same anaesthetic protocol. Arterial blood gases and osmolality, and plasma concentrations of glucose, sodium, potassium and chloride were measured. RESULTS: Intraoperatively, PaCO2 was higher during spontaneous-assisted ventilation than during intermittent negative-pressure ventilation (9 +/- 1.8 vs. 5.4 +/- 1.2 kPa, P < 0.001) and the pH was also lower during spontaneous-assisted ventilation than during intermittent negative-pressure ventilation (7.24 +/- 0.07 vs. 7.4 +/- 0.08, P < 0.001). Plasma potassium concentration remained similar in both groups (3.8 +/- 0.2 mmol L(-1) with spontaneous-assisted ventilation vs. 3.7 +/- 0.4 mmol L(-1) with intermittent negative-pressure ventilation). CONCLUSION: Acute respiratory acidosis does not affect plasma potassium concentration.     

Choice of opioid supplementation for day-case rigid bronchoscopy:a randomized placebo-controlled comparison of a bolus of remifentanil and alfentanil

OBJECTIVE: To compare the efficacy of different bolus doses of remifentanil, alfentanil, and saline at controlling the hemodynamic responses to day-case rigid bronchoscopy under general anesthesia. DESIGN: Prospective, randomized, double-blind, placebo-controlled study. SETTING: Tertiary referral cardiothoracic hospital, single center. PARTICIPANTS: Eighty consenting adults scheduled for elective day-case rigid bronchoscopy under general anesthesia. INTERVENTIONS: Patients were randomized to receive a bolus of 10 micro g/kg of alfentanil, 1 micro g/kg of remifentanil, 2 micro g/kg of remifentanil or saline. After this, anesthesia was induced and maintained with a target-controlled propofol infusion (TCI) and succinylcholine was used for muscle relaxation. Heart rate and noninvasive arterial pressure were measured at 1-minute intervals throughout. MEASUREMENTS AND MAIN RESULTS: Patients' characteristics were similar in all 4 groups. There were no differences in time to return of spontaneous ventilation, wake-up times, or use of rescue vasopressors, and no patients complained of postoperative nausea. Remifentanil provided greater hemodynamic stability than alfentanil and a bolus of remifentanil of 2 micro g/kg significantly attenuated the rise in heart rate and was the most effective in preventing a rise in blood pressure. CONCLUSIONS: A bolus of 2 micro g/kg of remifentanil successfully attenuated the hemodynamic response to rigid bronchoscopy without delaying recovery.     

General anaesthesia with target controlled infusion of propofol for planned caesarean section: maternal and neonatal effects of a remifentanil-based technique

The present case series evaluated maternal and neonatal effects of remifentanil, combined with propofol, during general anaesthesia for caesarean delivery. Following written informed consent, ten patients scheduled for semi-elective caesarean section were recruited to this prospective, unblinded trial. All patients with non-reassuring fetal status were excluded. A 0.50-micrograms/kg bolus of remifentanil was given intravenously, followed by a continuous infusion of 0.20 micrograms.kg(-1)min(-1). Anaesthesia was induced using propofol target controlled infusion set at a blood concentration of 5 micrograms/mL, 45 s after the remifentanil bolus. Following tracheal intubation the propofol target was reduced to 2.5 micrograms/mL and remifentanil maintained at 0.20 micrograms.kg(-1)min(-1). Mean arterial pressure remained stable throughout anaesthesia. Two patients experienced episodes of hypotension (mean arterial pressure decrease >20%). Although neonatal depression occurred in six babies and assisted mask ventilation was required briefly, recovery was rapid without the need for naloxone or tracheal intubation. Umbilical artery pH was >7.20 in all infants. We conclude that the results of the present case series using a remifentanil/propofol-based technique of general anaesthesia for caesarean section provide a basis to study the safety of this technique in a larger population. Under the conditions of the present trial, this anaesthetic technique seems safe for mother and infant, provided adequate precautions are taken to manage brief, self-limiting infant respiratory depression. At the moment we cannot advise the routine use of this technique, especially since it has not been studied in situations of fetal compromise.     

Bronchoscopy and nitrous oxide pollution

The purpose of the investigation was to assess the extent of nitrous oxide pollution during bronchoscopy (rigid ventilation bronchoscope) and further to elucidate the possible reduction in air pollution during local scavenging of leaking gas by a suction catheter placed in the pharynx. The study included 14 adult patients. The leakage of anaesthetic gas was 11.4 +/- 3.2 l min-1 and the median value of the nitrous oxide concentration in the breathing zone of the endoscopist was greater than 300 ppm. Air pollution could not be reduced significantly by scavenging with a suction catheter. The use of inhalation anaesthetics is therefore inadvisable during bronchoscopy in adults unless sufficient anaesthetic scavenging can be established. Other ways of reducing air pollution are discussed and the use of total intravenous anaesthesia or local anaesthesia is advocated.     

Remifentanil in combination with propofol for spontaneous ventilation anaesthesia

We have investigated the effect of four doses of remifentanil on the incidence of respiratory depression and somatic response at incision. Remifentanil was administered as a loading dose of 0.125, 0.25, 0.375 or 0.5 microgram kg-1 and at a maintenance infusion rate of 0.025, 0.05, 0.075 or 0.1 microgram kg-1 min-1, respectively, with an infusion of propofol 6 mg kg-1 h-1. Responses occurred in 88% of patients with remifentanil 0.025 microgram kg-1 min-1 compared with 30-40% in the other groups. Respiratory depression after incision increased from 6% with remifentanil 0.025 microgram kg-1 min-1 to 73% with 0.1 microgram kg-1 min-1. Increases in propofol infusion rate to 7.2-8.4 mg kg-1 h-1 produced adequate maintenance of anaesthesia. Reductions in remifentanil doses to 0.025-0.05 microgram kg-1 min-1 resulted in adequate respiration at the end of surgery in 88% of patients. Maintenance infusions of the two drugs for spontaneous ventilation are likely to be in these ranges. However, the ideal loading doses and infusion rates for induction remain to be established.      

The use of remifentanil for intubation in paediatric patients during sevoflurane anaesthesia guided by Bispectral Index (BIS) monitoring

We studied the intubating conditions, haemodynamic and endocrine changes following tracheal intubation during sevoflurane anaesthesia guided by Bispectral Index (BIS) monitoring in 40 children who received either remifentanil 1 microg.kg-1 (group R) or saline 1 ml.kg-1 (group S). Acceptable intubating conditions were found in all patients in group R (n = 20), compared to only 12 patients in group S (p = 0.002). There were no intergroup differences in heart rate, systolic blood pressure and plasma concentrations of epinephrine and norepinephrine at any time point and changes in haemodynamic variables throughout the study period were moderate. Titration of sevoflurane delivery to a target BIS of 35 +/- 5 led to almost equal end-tidal sevoflurane concentrations in either group and remifentanil did not affect the BIS. There were no side-effects in either group that required intervention. Intubating conditions during sevoflurane anaesthesia in children were found to be improved by a single bolus dose of remifentanil 1 microg.kg-1.     

Remifentanil and propofol for sedation in children and young adolescents undergoing diagnostic flexible bronchoscopy

Flexible fibreoptic bronchoscopy (FOB) has become a useful diagnostic and therapeutic procedure in children. We investigated 26 patients (3-14 years) for FOB using a new sedation strategy. All patients received oral premedication and inhalation of topical anaesthetic. Sedation for bronchoscopy was achieved with a continuous infusion of remifentanil and intermittent boluses of propofol. Propofol injection was repeated if sedation was inadequate. Sedation could be successfully performed in all children without adverse effects. Endtidal CO2 concentration and arterial oxygen saturation remained stable throughout the study. All children were awake 5+/-1.3 min after stopping remifentanil infusion. Sedation with remifentanil/propofol is a new sedation strategy for diagnostic flexible paediatric bronchoscopy in children with spontaneous ventilation.     

Pharmacokinetic-based total intravenous anaesthesia using remifentanil and propofol for surgical myocardial revascularization

BACKGROUND AND OBJECTIVE: We investigated the following aspects of pharmacokinetic-guided total intravenous anaesthesia with remifentanil and propofol in patients undergoing surgical myocardial revascularization: anaesthetic efficacy, haemodynamic effects, impact on extubation of the trachea and analgesia after operation. METHODS: Thirty-two patients undergoing on-pump coronary bypass surgery received intravenous anaesthesia with remifentanil and propofol. Both drugs were dosed and titrated based on computer-assisted pharmacokinetic models to maintain constant plasma concentrations. The propofol target plasma concentration was 1.2 microg mL(-1) throughout the procedure. A remifentanil target plasma concentration of 8 ng mL(-1) was achieved over 2 min for induction. After tracheal intubation, the opioid plasma concentration was reduced to 4 ng mL(-1), and then titrated up to 8 ng mL(-1) during surgery. Postoperative analgesia was managed with remifentanil infusion until 4 h after tracheal extubation, and a continuous infusion of tramadol was started 1 h before the remifentanil was stopped. RESULTS: After induction of anaesthesia, heart rate (-20%) and cardiac index (-6%) decreased significantly. No hypotensive episodes (mean arterial pressure < 60 mmHg) occurred. Intraoperative haemodynamics were stable. Three cases of myocardial ischaemia were detected: two by transoesophageal echocardiography and one with ST-segment monitoring. The duration of postoperative mechanical ventilation of the lungs was 95 +/- 13 min and the time to extubation was 150 +/- 18 min. Postoperative analgesia was satisfactory in all patients. CONCLUSIONS: Pharmacokinetic-based total intravenous anaesthesia with remifentanil and propofol provides adequate anaesthesia during coronary surgery with cardiopulmonary bypass and allows safe early extubation after operation.     

Spinal anaesthesia for inguinal hernia repair in high-risk neonates

To avoid the high incidence of respiratory complications associated with general anaesthesia in premature neonates, 44 spinal anaesthetics for inguinal hernia repair in very low birthweight infants were administered in 47 attempts. Hyperbaric tetracaine with epinephrine 1:200,000 was administered in a dose range of 0.27-1.10 mg.kg-1. Attempted lumbar puncture failed in three infants. In 24 procedures, spinal anaesthesia alone provided satisfactory operating conditions; in 20, supplementary inhalational general anaesthesia or iv ketamine was necessary. Perioperative apnoeic episodes requiring bag/mask assisted ventilation occurred in six infants. In five infants, apnoeic spells occurred in the postoperative period. No infant required tracheal intubation; there was no haemodynamic instability. Twenty-four infants required no postoperative analgesia. Our experience suggests that spinal anaesthesia for inguinal hernia repair in very low birth weight infants reduces but does not eliminate the risk of respiratory instability, and that supplementary anaesthesia is often necessary to provide satisfactory operating conditions.     

Comparison of Adenosine and Remifentanil Infusions as Adjuvants to Desflurane Anesthesia

Background: Because adenosine has been alleged to produce both anesthetic and analgesic sparing effects, a randomized, double-blinded study was designed to compare the perioperative effects of adenosine and remifentanil when administered as intravenous adjuvants during general anesthesia for major gynecologic procedures.

Methods: Thirty-two women were assigned randomly to one of two drug treatment groups. After premedication with 0.04 mg/kg intravenous midazolam, anesthesia was induced with 2 [micro sign]g/kg intravenous fentanyl, 1.5 mg/kg intravenous propofol, and 0.6 mg/kg intravenous rocuronium, and maintained with desflurane, 2%, and nitrous oxide, 65%, in oxygen. Before skin incision, an infusion of either remifentanil (0.02 [micro sign]g [middle dot] kg-1 [middle dot] min-1) or adenosine (25 [micro sign]g [middle dot] kg-1 [middle dot] min-1) was started and subsequently titrated to maintain systolic blood pressure, heart rate, or both within 10-15% of the preincision values.

Results: Adenosine and remifentanil infusions were effective anesthetic adjuvants during lower abdominal surgery. Use of adenosine (mean +/- SEM, 166 +/- 17 [micro sign]g [middle dot] kg-1 [middle dot] min-1) was associated with a significantly greater decrease in systolic blood pressure and higher heart rate values compared with remifentanil (mean +/- SEM, 0.2 +/- 0.03 [micro sign]g [middle dot] kg-1 [middle dot] min-1). Total postoperative opioid analgesic use was 45% and 27% lower in the adenosine group at 0-2 h and 2-24 h after surgery, respectively.