The objectives are to measure diaphragm contractility directly in animals with respiratory alterations and to describe how pressure support ventilation affects diaphragm contractility. Breathing is a type of muscular exercise that may be assessed by measuring the mechanical work performed by respiratory muscles or by estimating the total energy cost of breathing by measuring oxygen consumption. The diaphragm is responsible for approximately 80% of the work of breathing and in certain situations, when the diaphragm becomes fatigued, patients experience respiratory difficulty. Nurses at the beside can monitor diaphragm fatigue only through indirect measures such as dyspnea, tachycardia, asychronized rib cage and abdominal movement. The overall research objective of the proposal is to utilize a miniaturized ultrasound device to directly measure diaphragm contractile movements in an animal model as a index of the work of breathing.
The specific aims of this proposal are: effectiveness studies related to diaphragm contractility. investigate diaphragm to conduct fatigue during respiratory acidosis (normoxic/hypercapnic states) to explore diaphragm fatigue during hypoxia (hypoxia/normocapnic, hypoxia/hypocapnic & hypoxia/hypercapnic) states, and to examine the effectiveness of pressure support ventilation in rats to reduce diaphragm fatigue. In all studies, diaphragm fatigue will be defined as a 50 % reduction in the diaphragm contractility waveform produced by an ultrasound device. During the experiments diaphragm fatigue will be induced in rats that will develop diaphragm fatigue as assessed by the miniaturized ultrasound device by altering the inspired oxygen and carbon dioxide concentrations. These rats will be exposed to various concentrations of oxygen and carbon dioxide to produce different respiratory alterations (normoxic, hypoxic, normocapnic, hypercapnic & hypocapnic states). These experiments will mimic ventilation/perfusion alterations commonly observed in nursing practice by changes in arterial blood gas concentrations. The experiment will include mechanically ventilated rats with induced diaphragm fatigue as assessed by the ultrasound device. These experimental rats will be exposed to four levels of pressure support ventilation (PSV) to determine the effect of PSV on diaphragm fatigue. All baseline data from all rats will serve as control measures.

Agency
National Institute of Health (NIH)
Institute
National Institute of Nursing Research (NINR)
Type
Academic/Teacher Award (ATA) (K07)
Project #
1K07NR000059-01
Application #
3078040
Study Section
National Institute of Nursing Research Initial Review Group (NRRC)
Project Start
1993-09-01
Project End
1996-08-31
Budget Start
1993-09-01
Budget End
1994-08-31
Support Year
1
Fiscal Year
1993
Total Cost
Indirect Cost
Name
University of Kansas
Department
Type
Schools of Nursing
DUNS #
016060860
City
Kansas City
State
KS
Country
United States
Zip Code
66160
Goodyear-Bruch, Caryl; Long, L Rae; Simon, Peggy et al. (2005) Pressure-support ventilation and diaphragm shortening in the rat model. AANA J 73:277-83
Pierce, J D; Clancy, R L (2001) Effects of hypoxia on diaphragm activity in anesthetized rats. J Perianesth Nurs 16:181-6
Isaacson, J; Smith-Blair, N; Clancy, R L et al. (2000) Effects of pressure support ventilation and continuous positive airway pressure on diaphragm performance. J Adv Nurs 32:1442-9
Pierce, J D; Clancy, R L; Trank, J W et al. (1998) Diaphragm shortening and intrathoracic pressure during hypercapnia in rats. Respir Med 92:4-8