A study to determine the optimum dose of metaraminol required to increase blood pressure by 25% during subarachnoid anaesthesia.

Abstract

We studied dosage optimization for metaraminol when managing hypotension during subarachnoid anaesthesia. Twenty patients aged 53 to 84 years, were recruited. Non-invasive blood pressure (BP) and heart rate were recorded one-minutely. A series of four i.v. metaraminol boluses (0.25 to 1.0 mg per 50 kg adult) were administered. From individual patient time plots of BP predicted dosages for a 25% elevation in BP were estimated. Dose-related elevations in systolic BP [mean (SD)] occurred following dosages of 0.5 mg [25 (11)%] and 1.0 mg [50 (23)%]. Similar elevations occurred in mean and diastolic BP. Overall estimated dosage (median) to produce a 25% elevation in systolic BP was 0.5 mg (per 50 kg adult). However, individual patient responses varied (10-90th centiles = 0.23 to 0.80 mg). Thus, we now recommend a starting dose of 0.25 mg, increasing to 0.5 mg if necessary, to treat hypotension (25% decrease in systolic BP) during subarachnoid anaesthesia.

• Authors: L A Critchley, M K Karmakar, J H Cheng, J A Critchley
• Journal: Anaesthesia and intensive care (Anaesth Intensive Care) Vol. 27 Issue 2 Pg. 170-4 (Apr 1999) ISSN: 0310-057X [Print] United States
• PMID: 10212714 (Publication Type: Journal Article)

Chemical References

• Vasoconstrictor Agents
• Metaraminol

Topics

• Aged
• Aged, 80 and over
• Anesthesia, Conduction
• Blood Pressure (drug effects)
• Dose-Response Relationship, Drug
• Electrocardiography
• Female
• Heart Rate (drug effects)
• Humans
• Hypotension (drug therapy)
• Infusions, Intravenous
• Male
• Metaraminol (administration & dosage)
• Middle Aged
• Monitoring, Intraoperative
• Subarachnoid Space
• Vasoconstrictor Agents (administration & dosage)