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


CONCLUSIONS
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.
Nishikawa
Kohki
K
Department of Anesthesiology, Sapporo Medical University, School of Medicine, Sapporo, Japan. nkouki@sapmed.ac.jp
Yamakage
Michiaki
M
Omote
Keiichi
K
Namiki
Akiyoshi
A
D000368:Aged; D000775:Anesthesia, Spinal / Q000009:adverse effects*; D001794:Blood Pressure / Q000187:drug effects; D004311:Double-Blind Method; D005260:Female; D006620:Hip Fractures / Q000601:surgery*; D006801:Humans; D006973:Hypertension / Q000150:complications; D007022:Hypotension / Q000453:epidemiology / Q000517:prevention & control*; D007273:Injections, Intramuscular; D007431:Intraoperative Complications / Q000453:epidemiology / Q000517:prevention & control*; D008297:Male; D019637:Orthopedic Procedures; D010147:Pain Measurement; D010656:Phenylephrine / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D014662:Vasoconstrictor Agents / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*
D014662:Vasoconstrictor Agents; D010656:Phenylephrine