Ventilatory response to CO2 following axillary blockade with bupivacaine.
The systemic effect of bupivacaine on the control of ventilation was studied in eight ASA I (six male, two female) unpremedicated healthy subjects aged 30-55 yr (mean 43.5 yr) and weighing 59-82 kg (mean 69 kg) after axillary blockade with bupivacaine 0.5% without epinephrine, 3 mg/kg. The slope of the ventilatory response to CO2 was significantly increased (P less than 0.05) from its control value (1.77 +/- 1.03 l X min-1 X mmHg-1 [mean +/- SD]) 30 min (+19 +/- 32%) and 60 min (+32 +/- 37%) after axillary blockade, while plasma bupivacaine levels were 1.65 +/- 0.82 and 1.40 +/- 0.60 micrograms/ml, respectively. The correlation between individual plasma bupivacaine levels and the changes in the slope of the ventilatory response to CO2 was significant (r = 0.57, n = 16, P less than 0.05). Resting minute ventilation and end-tidal CO2 values did not change significantly. These results suggest that bupivacaine has a systemic stimulating effect on the ventilatory control mechanisms.
D000328:Adult; D000772:Anesthesia, Local; D001365:Axilla; D002045:Bupivacaine / Q000097:blood / Q000494:pharmacology*; D002245:Carbon Dioxide; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012119:Respiration / Q000187:drug effects*; D012129:Respiratory Function Tests
D002245:Carbon Dioxide; D002045:Bupivacaine