ABSTRACT
OBJECTIVE: To test the hypothesis that nitric oxide inhalation facilitates CO2 elimination by decreasing alveolar deadspace in an ovine model of acute lung injury. DESIGN: Prospective, placebo-controlled, randomized, crossover model. SETTING: University research laboratory. SUBJECTS: Eleven mixed-breed adult sheep. INTERVENTIONS: To induce acute lung injury, hydrochloric acid was instilled into the tracheas of paralyzed sheep receiving controlled mechanical ventilation. Each sheep breathed 0 ppm, 5 ppm, and 20 ppm nitric oxide in random order. MEASUREMENTS AND MAIN RESULTS: Estimates of alveolar deadspace volumes and arterial-to-end tidal CO2 partial pressure differences were used as indicators of CO2 elimination efficiency. At a constant minute ventilation, nitric oxide inhalation caused dose-independent decreases in Paco2 (p <.05), alveolar deadspace (p <.01), and arterial-to-end tidal CO2 partial pressure differences (p <.01). We found that estimates of arterial-to-end tidal CO2 partial pressure differences may be used to predict alveolar deadspace volume (r2 =.86, p <.05). CONCLUSIONS: Estimates of arterial-to-end tidal CO2 partial pressure differences are reliable indicators of alveolar deadspace. Both values decreased during nitric oxide inhalation in our model of acutely injured lungs. This finding supports the idea that nitric oxide inhalation facilitates CO2 elimination in acutely injured lungs. Future studies are needed to determine whether nitric oxide therapy can be used to reduce the work of breathing in selected patients with cardiopulmonary disorders.
Subject(s)
Carbon Dioxide/metabolism , Lung Injury , Nitric Oxide/pharmacology , Pulmonary Alveoli/metabolism , Pulmonary Gas Exchange/drug effects , Respiratory Dead Space , Administration, Inhalation , Analysis of Variance , Animals , Cross-Over Studies , Disease Models, Animal , Hemodynamics , Hydrochloric Acid , Lung/metabolism , Nitric Oxide/administration & dosage , Random Allocation , SheepABSTRACT
OBJECTIVE: To test the effectiveness of gastric insufflation as an adjunct to placement of feeding tubes in the small bowel. DESIGN: Prospective, randomized, controlled study. SETTING: Pediatric intensive care unit in a tertiary children's hospital. PATIENTS: A total of 50 children requiring enteral nutrition via a nasoenteral feeding tube in the small bowel. INTERVENTIONS: An unweighted nasoenteral feeding tube attached to a three-way stopcock and a 60 mL syringe was inserted through the nares into the stomach. After 10 mL/kg of air was injected, the tube was advanced a distance estimated to position the tip of the tube proximal to the pylorus. An additional 10 mL/kg of air was then injected, and the tube was advanced a distance needed to place the tube in the fourth part of the duodenum. In the control group, feeding tubes were inserted through the nares and into the stomach. The tube was then advanced a distance estimated to place the tube in the fourth part of the duodenum. No air was injected in the control group. MEASUREMENTS AND MAIN RESULTS: When gastric insufflation was used, 23 of 25 feeding tubes were successfully placed in the small bowel on the first attempt compared with 11 of 25 in the control group (p = .001). All feeding tubes were successfully placed after two attempts in the gastric insufflation group compared with 18 of 25 in the control group (p < .001). The time between the first attempt at placement of a transpyloric feeding tube and the initiation of feeding was significantly shorter in the study group than in the control group. There were no complications in either group. CONCLUSION: Gastric insufflation allows rapid placement of feeding tubes into the small bowel with fewer attempts compared with a standard insertion technique in children.
