We propose to test the hypothesis that changes in lung and regional chest wall mechanical properties (i.e., impedances) are correlated with postoperative complications. Our studies will include three stages, each will answer important questions about respiratory mechanics in health and disease and provide background information to test our overall hypothesis. We will employ methods that we have recently developed that enable accurate measurement of regional chest wall impedance in the normal range of breathing amplitude and frequency. In those experiments where the airway is intubated, we will additionally measure lung impedance. In the first stage, we will examine how regional impedances of the chest wall in healthy subjects change throughout the course of daily activity, as the respiratory muscles are called upon to perform in many non-respiratory tasks (lifting, trunk turning, changing posture, different forms of exercise, etc.) We will be able to decide how certain posture, different forms of exercises affect chest wall impedance and how regional properties interact to determine the properties of the chest wall as a whole. In the second interact to determine the properties of the chest wall as a whole. In the second stage, we will study the effects of anesthesia and muscle paralysis on lung and regional chest wall impedances in healthy subjects in the laboratory. In particular, we will evaluate the extent of regional differences in chest wall impedance: if large, the differences may cause unequal distribution of ventilation and thereby lead to impairment of gas exchange, a major postoperative problem. In the third stage, we will make measurements of lung and regional chest wall impedances in patients before and after various types of surgery. The measurements before surgery will allow us to accumulate a data base of accurate, standardized measurements from a diverse sampling of patients, with healthy and diseased respiratory systems. These data will strengthen our ability to understand and diagnose respiratory disorders. The measurements after surgery, in the recovery room, will enable us to test for correlations between respiratory impedances and postoperative complications such as atelectasis. We will try to develop objective criteria for onset and reversal of respiratory postoperative complications, assist diagnosis and determine the efficacy of treatment regimens.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
First Independent Research Support & Transition (FIRST) Awards (R29)
Project #
5R29HL044128-05
Application #
2221335
Study Section
Respiratory and Applied Physiology Study Section (RAP)
Project Start
1990-01-01
Project End
1995-12-31
Budget Start
1994-01-01
Budget End
1995-12-31
Support Year
5
Fiscal Year
1994
Total Cost
Indirect Cost
Name
University of Maryland Baltimore
Department
Anesthesiology
Type
Schools of Medicine
DUNS #
003255213
City
Baltimore
State
MD
Country
United States
Zip Code
21201
Barnas, G M; Harinath, P; Green, M D et al. (1994) Influence of waveform and analysis technique on lung and chest wall properties. Respir Physiol 96:331-44
Barnas, G M; Watson, R J; Green, M D et al. (1994) Lung and chest wall mechanical properties before and after cardiac surgery with cardiopulmonary bypass. J Appl Physiol 76:166-75
Barnas, G M; Sprung, J (1993) Effects of mean airway pressure and tidal volume on lung and chest wall mechanics in the dog. J Appl Physiol 74:2286-93
Stamenovic, D; Lutchen, K R; Barnas, G M (1993) Alternative model of respiratory tissue viscoplasticity. J Appl Physiol 75:1062-9
Barnas, G M; Sprung, J; Craft, T M et al. (1993) Effect of lung volume on lung resistance and elastance in awake subjects measured during sinusoidal forcing. Anesthesiology 78:1082-90
Barnas, G M; Green, M D; Mackenzie, C F et al. (1993) Effect of posture on lung and regional chest wall mechanics. Anesthesiology 78:251-9
Barnas, G M; Stamenovic, D; Lutchen, K R (1992) Lung and chest wall impedances in the dog in normal range of breathing: effects of pulmonary edema. J Appl Physiol 73:1040-6
Barnas, G M; Stamenovic, D; Lutchen, K R et al. (1992) Lung and chest wall impedances in the dog: effects of frequency and tidal volume. J Appl Physiol 72:87-93
Barnas, G M; Mills, P J; Mackenzie, C F et al. (1992) Effect of tidal volume on respiratory system elastance and resistance during anesthesia and paralysis. Am Rev Respir Dis 145:522-6
Barnas, G M; Campbell, D N; Mackenzie, C F et al. (1992) Lung, chest wall, and total respiratory system resistances and elastances in the normal range of breathing. Am Rev Respir Dis 145:110-3

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