Evidence of acute tolerance to remifentanil in intensive care but not in anesthesia.

We report the case of a 19-year-old man with a drug abuse history, admitted to the intensive care unit for head and chest trauma, who experienced an acute tolerance to sedative and respiratory depression effects of remifentanil, which was given as the sole agent for sedation. He did not exhibit any signs of drug tolerance or intraoperative awareness during prolonged remifentanil-based anesthesia using propofol or sevoflurane as adjuvants. Several recent studies support the hypothesis of a possible involvement of N-methyl-d-aspartate glutamate receptors. The clinical relevance of this report is that if a patient with a previously acute tolerance to remifentanil during sedation undergoes long-term surgery, and propofol or sevoflurane is coadministered in a remifentanil-based anesthesia, the patient will not necessarily develop opioid tolerance. It is of interest for anesthesiologists, given the high frequency of patients with drug abuse history who are admitted to intensive care units, often sedated with remifentanil, who undergo anesthesia for emergency surgery.

Comparative cost-analysis of a propofol-cisatracurium-based anesthesia with remifentanil or fentanyl for laparoscopic surgery.

To compare the intraoperative costs of intravenous propofol-based anesthesia for laparoscopic cholecystectomy, a total of 42 patients were randomly assigned to receive remifentanil or fentanyl as adjuvant using the bispectral index anesthesia monitoring. The average anesthesia calculated costs per hour (and per minute) were 79.45 (1.32) in the fentanyl group and 65.36 (1.09) in the remifentanil group. The calculated mean cost per patient was 76.56 in the fentanyl group and 58.86 in the remifentanil group. In conclusion, for propofol-cisatracurium-based anesthesia for laparoscopic surgery, when applying the bispectral index to guide the administration of hypnotic anesthetic drugs and ensure an adequate and stable depth of anesthesia, the cost of anesthesia is lower using remifentanil as an adjuvant rather than fentanyl. The clinical relevance is that it could be the intravenous anesthesia technique of choice in laparoscopic surgery for cholecystectomy from a cost-minimization standpoint.

Hypercapnia: what is the limit in paediatric patients? A case of near-fatal asthma successfully treated by multipharmacological approach.

We describe a case of prolonged severe hypercapnia with respiratory acidosis occurring during an episode of near-fatal asthma in an 8-year-old boy, followed by complete recovery. After admission to the intensive care unit, despite treatment with maximal conventional bronchodilatative therapy, the clinical picture deteriorated with evident signs of respiratory muscle fatigue. The child was sedated, intubated and mechanically ventilated. Magnesium sulphate, ketamine and sevoflurane were gradually introduced together with deep sedation, curarization and continuous bronchodilatative therapy. Ten hours after admission, arterial pCO2 reached 39 kPa (293 mmHg), pH was 6.77 and pO2 8.6 kPa (65 mmHg). Chest radiograph showed severe neck subcutaneous emphysema, with signs of mediastinal emphysema. No episode of haemodynamic instability was seen despite severe prolonged hypercapnia lasting more than 14 h. Oxygenation was maintained and successful recovery followed without neurological or cardiovascular sequelae. This case shows the cardiovascular and neurological tolerance of a prolonged period of supercarbia in a paediatric patient. The most important lesson to be learned is the extreme importance of maintaining adequate tissue perfusion and oxygenation during an asthma attack. The second lesson is that when conventional bronchodilators fail, the intensivist may resort to the use of drugs such as ketamine, magnesium sulphate and inhalation anaesthesia. In this context deep sedation and curarization are important not only to improve oxygenation, but also to reduce cerebral metabolic requirements.

Transcranial Doppler ultrasound study of the effects of nitrous oxide on cerebral autoregulation during neurosurgical anesthesia: a randomized controlled trial.

OBJECT: Nitrous oxide has an adverse effect on cerebrovascular hemodynamics. Increased intracranial pressure, cerebral blood flow (CBF), cerebral metabolic rate of O2 (CMRO2), and reduced autoregulation indices have been reported, but their magnitudes are still being debated. This study was designed to evaluate the effect of N2O on CBF and autoregulatory indexes during N2O-sevoflurane anesthesia in a prospective randomized controlled series of patients. METHODS: Two groups of 20 patients were studied on the basis of the use of N2O in the anesthetic gas mixture. The transient hyperemic response test, which relies on transcranial Doppler ultrasound techniques, was used to assess cerebral hemodynamics. The time-averaged mean flow velocity, considered to be an index of actual CBF, increased significantly (p < 0.001) after introduction of N2O. The hyperemic response, considered as the index of autoregulatory potential, decreased significantly after introduction of N2O into the gas mixture (p < 0.001). CONCLUSIONS: The increase in CBF and the reduction in autoregulatory indices suggest caution in using N2O during sevoflurane anesthesia, especially in patients with reduced autoregulatory reserve and during neurosurgical interventions. Transcranial Doppler ultrasonography is an efficacious method to evaluate the effects of anesthetic agents on CBF.