[Effects of midazolam on respiratory drive in healthy volunteers].
OBJECTIVE
To compare the effects of a sedative dose of midazolam on mean inspiratory flow (VT/TI = index of central respiratory activity), known as being decreased by midazolam and the intercostal muscle activity, known as being increased by this agent.


METHODS
Laboratory study.


METHODS
Seven healthy volunteers.


METHODS
After assessment of baseline values of ventilatory variables and intercostal electromyographic activity (in arbitrary units), midazolam 0.1 mg.kg-1 was administered by iv route. The measurements were repeated after 5 and 10 min, and finally 2 min after the i.v. injection of flumazenil 1 mg.


RESULTS
Midazolam decreased VE and VT. Similarly VT/TI ratio decreased from 0.44 +/- 0.04 (baseline value) to 0.26 +/- 0.03 (5 min) and 0.3 +/- 0.03 L.s-1 (10 min later) respectively (P < 0.05). Conversely, midazolam increased the intercostal electromyographic activity from 4.0 +/- 0.7 (baseline value) to 26.5 +/- 16.6 (5 min) and 28.4 +/- 16.6 U (10 min later) respectively (P < 0.05). Within 2 min after flumazenil administration all variables returned to baseline values.


CONCLUSIONS
The decrease of VT/TI ratio is probably linked to increased resistances in the upper airways. This ratio cannot act as an indicator of respiratory drive during sedation or anaesthesia. The assessment of the ventilatory effects of benzodiazepines must be based simultaneously of the various other indicators of the ventilatory drive, as these agents act on the different stages of the ventilatory cycle and therefore cannot be characterized by a unique variable.
D000759:Adjuvants, Anesthesia; D000328:Adult; D000403:Airway Resistance / Q000187:drug effects; D004576:Electromyography; D005442:Flumazenil / Q000494:pharmacology; D006801:Humans; D007366:Intercostal Muscles / Q000187:drug effects; D008176:Lung Volume Measurements; D008297:Male; D008874:Midazolam / Q000494:pharmacology*; D012119:Respiration / Q000187:drug effects*; D012125:Respiratory Center / Q000187:drug effects
D000759:Adjuvants, Anesthesia; D005442:Flumazenil; D008874:Midazolam
Effets du midazolam sur la commande ventilatoire chez le volontaire sain.