THE EFFECTS OF BOLUS ADMINISTRATION OF OPIOIDS ON CEREBROSPINAL-FLUIDPRESSURE IN PATIENTS WITH SUPRATENTORIAL LESIONS

In many studies reporting an increase in cerebrospinal fluid pressure (CSFP) after opioid administration, concomitant decreases in mean arte rial pressure (MAP) have been observed. Autoregulatory cerebral vasodi lation may therefore have been a factor in the CSFP increases. We test ed the hypothesis that increases in CSFP after bolus injection of opio ids could be minimized by modifying concomitant decreases in MAP with phenylephrine. Thirty-three patients with supratentorial mass lesions were studied in a randomized, prospective, double-blind, saline-contro lled comparative trial. The principal outcome measures were lumbar CSF P, MAP, and heart rate (HR). Study drugs, sufentanil 0.8 mu g/kg (n = 12), fentanyl 4.5 mu g/kg (n = 11), or normal saline (n = 10), were in jected intravenously (IV) during stable general anesthesia with 0.3-0. 7 minimum alveolar anesthetic concentration (MAC) of isoflurane in oxy gen and controlled ventilation (end-tidal carbon dioxide 32-35 mm Hg). Phenylephrine 50-100 mu g was injected IV when MAP decreased by more than 15% of initial values, and atropine 0.5 mg IV when HR decreased t o less than 45 bpm. Opioid administration was associated with signific ant decreases in MAP, 21 +/- 9 mm Hg (mean +/- SD) in the sufentanil g roup and 16 +/- 7 mm Hg in the fentanyl group; P < 0.001. These decrea ses in MAP were of short duration (i.e., corrected with 1-2 min). Pati ents in the sufentanil group needed more phenylephrine than patients i n the fentanyl group (170 +/- 89 mu g vs 100 +/- 47 mu g; P < 0.05). N o significant change in the CSFP was seen in either the sufentanil-(1 +/- 6 mm Hg) or fentanyl-treated patients (0 +/- 2 mm Hg). No signific ant changes in MAP or CSFP were observed in the saline-treated patient s. HR decreased after injection of either study drug (P < 0.01) but re mained unchanged in the saline group. In summary, during stable anesth esia with isoflurane in oxygen, bolus injections of fentanyl or sufent anil, despite producing rapidly corrected mean decreases in MAP of 18% and 25%, respectively, were not associated with any change in CSFP.