Letters to the Editor: Letters & Announcements
To the Editor:
With regard to the article by Grottkey et al. (1), in assessing the wake-up test, the technique is based on the integrity of voluntary motor power without the use of any special equipment (2), yet the authors used cisatracurium for muscle relaxation at the beginning of surgery but made no reference to neuromuscular junction monitoring nor to any maintenance muscle relaxant use. Was there any difference in the recovery of neuromuscular function between the three groups, especially in the propofol/sufentanil group?
Because the authors did not study a homogenous group (patients in the propofol/sufentanil group were significantly older than those in the other two treatment groups), one can expect some pharmacodynamic and pharmacokinetic differences between the groups. For example, propofol, a lipid-soluble anesthetic, has a prolonged effect in the elderly because of their higher proportion of body fat to total body weight (3,4). Moreover, as the authors used the same propofol target-controlled infusion doses (plasma concentration, 2–4 μg/mL) for maintenance of anesthesia, was there no difference in the mean propofol requirement between the older and the younger patients? If the older and younger patients were given the same cumulative dose of propofol, one would expect a more pronounced central nervous system depressant effect in the older patient population.
Finally, the authors noted no difference in the postoperative analgesic requirements or pain scores between the groups but did not describe the extent of surgery: were these pauci-level or multilevel spinal surgeries? This could affect the severity of postoperative pain and the perioperative analgesic requirement.
Olubukola O. Nafiu, MD
Department of Anesthesiology
University of Michigan
Ann Arbor, MI
1. Grottke O, Dietrich PJ, Wiegels S, Wappler F. Intraoperative wake-up test and postoperative emergence in patients undergoing spinal surgery: A comparison of intravenous and inhaled anesthetic techniques using short-acting anesthetics Anesth Analg 2004;99:1521–7.
2. Vauzelle C, Stagnara P, Jouvinroux P. Functional monitoring of spinal cord activity during spinal surgery. Clin Orthop 1973;93:173–8.
3. Kirkpatrick T, Cockshott ID, Douglas EJ, Nimmo WS. Pharmacokinetics of propofol (diprivan) in elderly patients. Br J Anaesth 1988;60:146–50.
4. Schnider TW, Minto CF, Shafer SL, et al. The influence of age on propofol pharmacodynamics. Anesthesiology 1999;90:1502–16.