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.

Perinatal neuroprotection by muscle relaxants against hypoxic-ischemic lesions: is it a possible hypothesis?

The incidence of neurological disabilities ascribable to hypoxia-ischemia in the perinatal period (HIPP) is rising. Glutamate plays a key role in the development of cerebral damage related to HIPP: it triggers the excitotoxic cascade by overactivating N-methyl-D-aspartate receptors (NMDA), implicated as important mediators of both learning and neuronal development. Laudanosine is the metabolite of the neuromuscular blocking drugs, atracurium and cisatracurium, administered as part of obstetric general anesthesia. In elective cesarean section, laudanosine may be found in the fetus with a mean umbilical vein concentration of 26 (range 6-60) ng ml(-1). At nM concentrations, laudanosine can activate alpha4beta2 nACh subtype receptors. Activation of alpha4beta2 nAChRs provided neuroprotection against NMDA excitotoxic cascade in a neonatal model. Taken together, experimental and clinical data widely indicate a potential neuroprotective role for laudanosine against perinatal brain lesions of hypoxic-ischemic origin. The clinical relevance is that administration of the neuromuscular blocking drugs atracurium and cisatracurium, administered as part of general anesthesia for cesarean section, could be potentially therapeutic in obstetric anesthesia. Therefore, we find laudanosine to be an attractive proposal for further studies in the prevention of neurological disabilities ascribable to perinatal injury related to hypoxia and ischemia.

[Substernal goiter: pre-, intra- and postoperative problems]. / Le problematiche pre-, intra- e postoperatorie del gozzo immerso.

The Authors report their experience with problems in treating substernal goiter. They then explain at length the complex haemodynamic or respiratory situations encountered and the therapeutic management of the condition. Also discussed are technical surgical problems, and the prevention and therapy of possible complications. They conclude by stating that thanks to all the technical means currently available complete patient control can be achieved before, during and after the operation, thus significantly contributing to the successful outcome of surgical treatment.

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.