Anaesthetic requirements and stress hormone responses in acute cord-injured patients undergoing surgery of the injured spine:

Anesthetic requirements and stress hormone responses in chronic spinal cord-injured patients undergoing surgery below the level of injury: nitrous oxide vs remifentanil

BACKGROUND

Nitrous oxide (N2O) and remifentanil both have anesthetic-reducing and antinociceptive effects. We aimed to determine the anesthetic requirements and stress hormone responses in spinal cord-injured (SCI) patients undergoing surgery under sevoflurane anesthesia with or without pharmacodynamically equivalent doses of N2O or remifentanil.

METHODS

Forty-five chronic, complete SCI patients undergoing surgery below the level of injury were randomly allocated to receive sevoflurane alone (control, n = 15), or in combination with 67% N2O (n = 15) or target-controlled infusion of 1.37 ng/ml remifentanil (n = 15). Sevoflurane concentrations were titrated to maintain a Bispectral Index (BIS) value between 40 and 50. Measurements included end-tidal sevoflurane concentrations, mean arterial blood pressure (MAP), heart rate (HR), and plasma catecholamine and cortisol concentrations.

RESULTS

During surgery, MAP, HR, and BIS did not differ among the groups. Sevoflurane concentrations were lower in the N2O group (0.94 ± 0.30%) and the remifentanil group (1.06 ± 0.29%) than in the control group (1.55 ± 0.34%) (P < 0.001, both). Plasma concentrations of norepinephrine remained unchanged compared to baseline values in each group, with no significant differences among groups throughout the study. Cortisol levels decreased during surgery as compared to baseline values, and returned to levels higher than baseline at 1 h after surgery (P < 0.05) without inter-group differences.

CONCLUSIONS

Remifentanil (1.37 ng/ml) and N2O (67%) reduced the sevoflurane requirements similarly by 31-39%, with no significant differences in hemodynamic and neuroendocrine responses. Either remifentanil or N2O can be used as an anesthetic adjuvant during sevoflurane anesthesia in SCI patients undergoing surgery below the level of injury.

'Anesthesia' for awake neurosurgery

PURPOSE OF REVIEW

In this review we focus on recent findings in the anesthetic management of patients undergoing craniotomy while awake, and propose a structured approach to the clinical practice of 'anesthesia' for awake neurosurgery.

RECENT FINDINGS

The increasing use of functional neurosurgery and recent evidence favoring resection of tumor involving eloquent cortex has expanded the indications for awake craniotomy, a procedure needing a fully cooperative patient and expert intraoperative anesthetic management. Despite the shorter hospital stay, the more recently published studies have highlighted perioperative anesthetic complications and have proposed ways to improve anesthesia techniques for awake procedures in adults and children.

SUMMARY

Although anesthesia for awake craniotomy is usually a well tolerated procedure it requires an extensive knowledge of the principles underlying neuroanesthesia and of specific technical strategies including local anesthesia for scalp blockade, advanced airway management, dedicated sedation protocols, and skillful management of hemodynamics.