Biomaterial Database

A method for noninvasive determination of inspiratory resistance during proportional assist ventilation. 2001

M Younes, and J Kun, and B Masiowski, and K Webster, and D Roberts

Sections of Respiratory and Clinical Care Medicine, University of Manitoba, Winnipeg, Manitoba, Canada. younesmk@cc.umanitoba.ca

Currently available noninvasive methods for measuring inspiratory resistance (RI) are difficult to implement or interpret during assisted mechanical ventilation on account of the confounding effect of respiratory efforts (Pmus). We propose a simple method consisting of brief reductions in airway pressure (Paw) in the early part of the inflation phase (pulse). Paw, flow (V), and volume (V) are measured at the beginning of the pulse (T (0)), at the trough of the pulse (TI) and at a point 0.1 s before T(0) (T(-1)). Equations of motion of the form [Pmus + Paw = V. K(1) + V (2). K(2) +V. E] are generated for the data at the three time points (E = elastance, K(1) and K(2) are Rohrer's constants). These three equations can be solved for K(1) and K(2) if it is arranged that the pulse has appropriate configuration and timing, and if it is assumed that DeltaPmus/Deltat is constant over the brief pulse period. The method was tested in 67 patients ventilated with proportional assist ventilation (PAV). The results were compared with those obtained using the interrupter technique during a period of controlled mechanical ventilation (CMV). RI, expressed at a standard flow of 1 L. s(-)(1), was slightly higher during PAV (16.4 +/- 4.9 versus 15.5 +/- 4.5 cm H(2)O. L(-1). s, p < 0.001). The average difference was 0.9 +/- 2.0 cm H(2)O. L(-1). s, corresponding to 5.4 +/- 12.6% of the average of RCMV and RPAV. The correlation coefficient was 0.92 (p = 8E-28) with a slope (1.01) and intercept (0.8) not significantly different from 1.0 and 0, respectively. We conclude that brief negative pulses applied early during the inflation phase can be used to provide reliable estimates of inspiratory resistance during PAV.

UI	MeSH Term	Description	Entries
D007362	Intensive Care Units	Hospital units providing continuous surveillance and care to acutely ill patients.	ICU Intensive Care Units,Intensive Care Unit,Unit, Intensive Care
D008297	Male		Males
D008962	Models, Theoretical	Theoretical representations that simulate the behavior or activity of systems, processes, or phenomena. They include the use of mathematical equations, computers, and other electronic equipment.	Experimental Model,Experimental Models,Mathematical Model,Model, Experimental,Models (Theoretical),Models, Experimental,Models, Theoretic,Theoretical Study,Mathematical Models,Model (Theoretical),Model, Mathematical,Model, Theoretical,Models, Mathematical,Studies, Theoretical,Study, Theoretical,Theoretical Model,Theoretical Models,Theoretical Studies
D008991	Monitoring, Physiologic	The continuous measurement of physiological processes, blood pressure, heart rate, renal output, reflexes, respiration, etc., in a patient or experimental animal; includes pharmacologic monitoring, the measurement of administered drugs or their metabolites in the blood, tissues, or urine.	Patient Monitoring,Monitoring, Physiological,Physiologic Monitoring,Monitoring, Patient,Physiological Monitoring
D011336	Probability	The study of chance processes or the relative frequency characterizing a chance process.	Probabilities
D012121	Respiration, Artificial	Any method of artificial breathing that employs mechanical or non-mechanical means to force the air into and out of the lungs. Artificial respiration or ventilation is used in individuals who have stopped breathing or have RESPIRATORY INSUFFICIENCY to increase their intake of oxygen (O2) and excretion of carbon dioxide (CO2).	Ventilation, Mechanical,Mechanical Ventilation,Artificial Respiration,Artificial Respirations,Mechanical Ventilations,Respirations, Artificial,Ventilations, Mechanical
D012129	Respiratory Function Tests	Measurement of the various processes involved in the act of respiration: inspiration, expiration, oxygen and carbon dioxide exchange, lung volume and compliance, etc.	Lung Function Tests,Pulmonary Function Tests,Function Test, Pulmonary,Function Tests, Pulmonary,Pulmonary Function Test,Test, Pulmonary Function,Tests, Pulmonary Function,Function Test, Lung,Function Test, Respiratory,Function Tests, Lung,Function Tests, Respiratory,Lung Function Test,Respiratory Function Test,Test, Lung Function,Test, Respiratory Function,Tests, Lung Function,Tests, Respiratory Function
D012131	Respiratory Insufficiency	Failure to adequately provide oxygen to cells of the body and to remove excess carbon dioxide from them. (Stedman, 25th ed)	Acute Hypercapnic Respiratory Failure,Acute Hypoxemic Respiratory Failure,Hypercapnic Acute Respiratory Failure,Hypercapnic Respiratory Failure,Hypoxemic Acute Respiratory Failure,Hypoxemic Respiratory Failure,Respiratory Depression,Respiratory Failure,Ventilatory Depression,Depressions, Ventilatory,Failure, Hypercapnic Respiratory,Failure, Hypoxemic Respiratory,Failure, Respiratory,Hypercapnic Respiratory Failures,Hypoxemic Respiratory Failures,Respiratory Failure, Hypercapnic,Respiratory Failure, Hypoxemic,Respiratory Failures
D005260	Female		Females
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man