Twenty-four patients who had acute respiratory insufficiency necessitating mechanical ventilation were studied. Twelve patients had controlled mechanical ventilation (CMV) with T-tube trials of spontaneous ventilation to accomplish weaning. Twelve received intermittent mandatory ventilation (IMV), a method of mechanical ventilation that allows spontaneous respirations to occur but provides periodic mechanical hyperinflations. Weaning was accomplished by increasing the interval between mechanical breaths until the patient's ventilation was entirely spontaneous. Arterial blood gas tensions, pH, dead space to tidal volume ratio, oxygen consumption, vital capacity, and inspiratory force were monitored for all patients until weaning was complete. The functional residual capacity was reduced in all patients following mechanical ventilation. Controlled mechanical ventilation resulted in alkalosis, an increased ventilation time, and an increase in oxygen consumption compared to IMV.
Downs JB, Perkins HM, Modell JH. Intermittent Mandatory VentilationAn Evaluation. Arch Surg. 1974;109(4):519-523. doi:10.1001/archsurg.1974.01360040041010