Failure of manual respiration

Abstract

The tidal volumes moved during performance of the BPAL and CPAL methods in 29 curarized, anesthetized, apneic adults were measured with a spirometer through an oronasal mask (with and without an artificial oropharyngeal airway in place) and through a tracheal tube. With the conventional BPAL method without an artificial airway the average tidal volume was zero, or less than dead space air in 12 of 15 subjects studied. The failure was mainly due to pharyngeal obstruction by the relaxed tongue, occurring when the neck was flexed and the mandible was not supported. An artificial oropharyngeal airway only slightly improved the tidal exchange. A modified BPAL method, which consisted of the head being tilted backward, increased the tidal volume and decreased the incidence of obstruction. With the conventional CPAL method the tidal volumes likewise depended mainly on the position of the head and neck. A modified CPAL method, which consisted of maintaining the head tilted backward by elevating the shoulders, was compared in 10 subjects with the modified BPAL method. The tidal volumes were greater and the incidence of upper airway obstruction was lower with the modified CPAL method. With a tracheal tube in place, tidal volumes of 260–840 ml were moved without signs of airway obstruction. The low values occurred in short and obese patients with reduced lung-thorax compliance. Submitted on August 28, 1958