Abstract

Little is known of the effects of low concentrations of inhaled nitric oxide (NO) on pulmonary mechanics and lung volumes in premature newborn infants with lung disease. Cardiopulmonary function tests including blood gas analyses were obtained from eleven premature lamb models with respiratory distress syndrome to determine if compliance, airways resistance, tidal volume, functional residual capacity, and gas exchange were affected. The effect of inhaled NO on the direction of shunting through the ductus arteriosus was determined using echocardiography.

Twin lambs were cannulated with arterial and venous catheters and intubated with an endotracheal tube before delivery on gestational day 126-130 (term 147-150 days). Modified natural surfactant (beractant) was given prior to mechanical ventilation. Lambs were stabilized and mechanically ventilated for 2 hours following surfactant delivery. Baseline cardiopulmonary functions were measured and lambs were randomly assigned to receive 20 ppm inhaled NO (0.90 O2, N2 balance) or no inhaled NO (control) for 30 minutes. Cardiopulmonary function tests were again measured, and the lambs were then switched to the alternate therapy for 30 minutes before obtaining another set of cardiopulmonary function tests.

Evaluation of these cardiopulmonary function tests demonstrated that lung compliance and tidal volume showed a percent decrease (12±6% sem, p=0.058; 15±6% sem, p=0.023, respectively) while functional residual capacity and airways resistance remained unchanged (p=0.666 and p=0.496, respectively). Oxygen ratios demonstrated a modest improvement in oxygenation (45±28% sem, p=0.074) following inhaled NO administration. While 27% of the experimental lambs showed an increased right-to-left shunting through the ductus arteriosus during control periods, none of the lambs exhibited right-to-left shunting while receiving inhaled NO.

Previous studies have demonstrated that administration of low concentrations of inhaled NO improves oxygenation. Although this study showed a modest improvement in oxygenation, it also has determined that lung compliance and tidal volume may decrease during inhaled NO delivery. It is possible that this worsening in lung mechanics and volumes could increase the risk for barotrauma and potentially contribute to the development of pulmonary edema. This suggests that the use of NO inhalation therapy as an adjunct to conventional therapies could damage the premature human neonate with respiratory failure.

LLU Discipline

Anatomy

Department

Anatomy

School

Graduate School

First Advisor

Michael A. Kirby

Second Advisor

Douglas D. Deming

Third Advisor

Andrew O. Hopper

Degree Name

Master of Science (MS)

Degree Level

M.S.

Year Degree Awarded

1995

Date (Title Page)

8-1995

Language

English

Library of Congress/MESH Subject Headings

Respiratory Distress Syndrome -- in infancy & childhood; Nitric Oxide

Type

Thesis

Page Count

2; vii; 90

Digital Format

PDF

Digital Publisher

Loma Linda University Libraries

Usage Rights

This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights.

Collection

Loma Linda University Electronic Theses and Dissertations

Collection Website

http://scholarsrepository.llu.edu/etd/

Repository

Loma Linda University. Del E. Webb Memorial Library. University Archives

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