Artificial ventilation by means of electrical activation of the intercostal/accessory muscles alone in anesthetized dogs.
We have previously shown that large inspired volumes can be achieved in phrenicotomized animals by intercostal/accessory muscle activation via spinal cord stimulation. In the present study, we evaluated the utility of this technique to provide complete ventilatory support for prolonged time periods (6 to 8 h, selected arbitrarily). In 10 deeply anesthetized dogs, a single electrode was introduced onto the epidural surface of the spinal cord and positioned at the T2-T3 spinal level. Bilateral phrenicotomy was performed in all animals to prevent possible diaphragm activation. The spinal cord was rhythmically stimulated approximately 13 times/min with trains of 15- to 20-Hz impulses of sufficient amplitude to achieve inspired volumes of 13 to 15 ml/kg and pressure-time index (product of duty cycle and delta P/Pmax) of less than 0.15 with each contraction. Level of alveolar ventilation was monitored by end-tidal PCO2 and intermittent arterial blood gas measurements. Mean inspired volume and minute ventilation were 236 +/- 7.84 (SE) ml and 3.12 +/- 0.13 (SE) L/min, respectively, and not significantly different between the first and sixth hours of continuous stimulation. Mean duty cycle (Ti/Ttot) was 0.26 +/- 0.01. Mean airway pressure (delta P) during prolonged electrical stimulation under conditions of airway occlusion was 8.05 +/- 0.61 (SE) cm H2O. Mean ratio of delta P/Pmax was 0.47 +/- 0.03 (SE) cm H2O; mean pressure-time index was 0.12 +/- 0.01 (SE). There was no evidence of system fatigue, as evidenced by the lack of any significant shift in the pressure frequency curve over a 6-h time period.(ABSTRACT TRUNCATED AT 250 WORDS)
DiMarco
A F
AF
Department of Medicine, Cleveland Metropolitan General Hospital, Ohio.
Budzinska
K
K
Supinski
G S
GS
D000768:Anesthesia, General; D000818:Animals; D004285:Dogs; D004599:Electric Stimulation Therapy; D004576:Electromyography; D007366:Intercostal Muscles / Q000294:innervation / Q000502:physiology*; D012121:Respiration, Artificial / Q000379:methods*; D012132:Respiratory Muscles / Q000294:innervation / Q000502:physiology*; D013116:Spinal Cord / Q000502:physiology*; D013997:Time Factors