Improvement In Ventilatory Efficiency Research Articles

Management of esophageal atresia and tracheoesophageal fistula in the neonate with severe respiratory distress syndrome

In a 10-year period, 22 neonates with esophageal atresia (EA) and tracheoesophageal fistula (TEF) required high pressure ventilatory support soon after birth because of respiratory distress syndrome (RDS). Eleven of the 22 or 50% survived overall, but if the 5 patients who died before definitive surgical repair could be attempted are excluded, 11 of 17 or 65% survived. More importantly, 4 of 7 (57%) patients who had gastrostomy performed first survived while 7 of 10 (70%) who had fistula ligation performed first survived. The difficulties with intraoperative management of those who had gastrostomy performed first were even more impressive. Our experience leads us to conclude that patients with EA and TEF with severe RDS who require high pressure ventilation preoperatively represent a group of patients who require special consideration. The danger to such patients with increased pulmonary resistance is not gastric distention but sudden loss of intragastric pressure. In the presence of poor lung compliance, the upper gastrointestinal tract functions in continuity with the tracheobronchial tree. A sudden loss of intragastric pressure, as with placement of a gastrostomy tube, results in an acute loss of effective ventilating pressure. Resuscitation of such a patient is not possible until leakage from the esophagus is controlled by ligation of the fistula or transabdominal occlusion of the distal esophagus. Placement of a Fogarty catheter into the fistula via a bronchoscope is effective but may not be feasible in every case. Early thoracotomy and ligation of the fistula in patients with progressive RDS provides immediate improvement in ventilatory efficiency and relief of gastric distention.

Effects of physical training on ventilatory equivalent and respiratory exchange ratio during weight supported, steady-state exercise.

Thirty-three college men participated in a 9-week endurance training program. An equal number of subjects served as controls. Pre- and post-test metabolic measurements were made during 10 min of submaximal exercise (1080 kpm/min at 60 rpm) and 15 min of recovery. Measurements included oxygen consumption, CO2 production, ventilatory equivalent (Ve/VO2 ratio) and respiratory exchange ratio (R). A three factor design variance analysis was used to analyze the effects of training on min-by-min exercise and recovery Ve/VO2 ratio and R. For the experimental group training resulted in a significant improvement in ventilatory efficiency during exercise, as well as a significant decrease in R. During recovery, Ve/VO2 and R decreased significantly for both groups although the magnitude of change was greater for the group that trained. Apparently, there was a significant habituation effect due to test procedures for the control group. The results are discussed in terms of lactate production and substrate utilization during exercise.

Influence of added dead space on pulmonary ventilation.

Summary.Hyperventilation due to extra dead space did not cause any significant improvement in ventilatory efficiency as measured in nitrogen wash‐out experiments during oxygen breathing. In the experiments with extra dead space a significant increase in degree of uniformity of ventilation could be demonstrated. The subject's dead space increased, and the over‐all efficiency remained constant. The efficiency‐improving effect of a better distribution and the efficiency‐deteriorating effect of a larger dead space probably cancelled out. The better distribution is most probably explained by the effect of mixing of gas from different lung fractions in the large dead space. The experiments were performed with a nitrogen meter.