Prophylactic IM small-dose phenylephrine blunts spinal anesthesia-induced hypotensive response during surgical repair of hip fracture in the elderly.

Abstract

UNLABELLED:

In a double-blinded, placebo-controlled, randomized study, we evaluated the effect of prophylactic IM phenylephrine at doses of 1.5 and 3 mg on hyperbaric tetracaine spinal anesthesia-induced hypotension in 90 normotensive and hypertensive patients aged >65 yr undergoing surgery for hip fracture. Thirty normotensive patients received 1.5 or 3 mg of phenylephrine IM (N/P-1.5 and N/P-3.0 groups; n = 15 in each), whereas controls received saline (N/C group; n = 15), and 45 hypertensive patients were treated in a similar manner (H/P-1.5, H/P-3.0, and H/C groups; n = 15 in each). All groups had a peak sensory block height of T9, with a range of T8 to T10. The incidence of hypotension (>25% decrease in mean arterial blood pressure [MAP] from baseline) was significantly lower in the patients who received phenylephrine 1.5 or 3 mg than in the controls, both in the normotensive and hypertensive groups (P < 0.01). The N/P-3.0 and N/P-1.5 groups and the H/P-3.0 group had significantly lower percentage reductions in MAP (P < 0.05) and required significantly smaller doses of rescue IV ephedrine (P < 0.05) than did the N/C group or the H/C group. The H/P-1.5 group also required significantly less rescue IV ephedrine (P < 0.05), although it was not sufficient to significantly attenuate the percentage decrease in MAP compared with that in the H/C group. Bradycardia (heart rate <50 bpm) as an adverse effect after IM administration of phenylephrine was not observed in any of the groups. Hypertension (MAP >20% increase from baseline) after medication occurred in the N/P-3.0 and H/P-3.0 groups, but not in the N/P-1.5 and H/P-1.5 groups. We conclude that prophylactic IM injection of 1.5 mg of phenylephrine is a safe (defined as the inhibition of bradycardia and hypertension) and effective means of reducing the incidence of hypotension associated with spinal anesthesia in normotensive and hypertensive elderly patients.

IMPLICATIONS:

We evaluated the efficacy and safety of small-dose IM phenylephrine for prophylaxis against spinal anesthesia-induced hypotension in normotensive and hypertensive elderly patients. Phenylephrine 1.5 mg IM was effective for reducing the incidence of hypotension and avoided adverse effects.

• Authors: Kohki Nishikawa, Michiaki Yamakage, Keiichi Omote, Akiyoshi Namiki
• Journal: Anesthesia and analgesia (Anesth Analg) Vol. 95 Issue 3 Pg. 751-6, table of contents (Sep 2002) ISSN: 0003-2999 [Print] United States
• PMID: 12198065 (Publication Type: Clinical Trial, Journal Article, Randomized Controlled Trial)

Chemical References

• Vasoconstrictor Agents
• Phenylephrine

Topics

• Aged
• Anesthesia, Spinal (adverse effects)
• Blood Pressure (drug effects)
• Double-Blind Method
• Female
• Hip Fractures (surgery)
• Humans
• Hypertension (complications)
• Hypotension (epidemiology, prevention & control)
• Injections, Intramuscular
• Intraoperative Complications (epidemiology, prevention & control)
• Male
• Orthopedic Procedures
• Pain Measurement
• Phenylephrine (administration & dosage, adverse effects, therapeutic use)
• Vasoconstrictor Agents (administration & dosage, adverse effects, therapeutic use)