Lung heterogeneity and deadspace volume in animals with acute respiratory distress syndrome using the inspired sinewave test
Journal
Physiological Measurement
Journal Volume
41
Journal Issue
11
Date Issued
2020
Author(s)
Tran M.C.
Crockett D.C.
Formenti F.
Phan P.A.
Hedenstierna G.
Larsson A.
Payne S.J.
Farmery A.D.
Abstract
Acute respiratory distress syndrome (ARDS) is associated with a high rate of morbidity and mortality, as patients undergoing mechanical ventilation are at risk of ventilator-induced lung injuries. Objective: To measure the lung heterogeneity and deadspace volume to find safer ventilator strategies. The ventilator settings could then offer homogeneous ventilation and theoretically equalize and reduce tidal strain/stress in the lung parenchyma. Approach: The inspired sinewave test (IST) is a non-invasive lung measurement tool which does not require cooperation from the patient. The IST can measure the effective lung volume, pulmonary blood flow and deadspace volume. We developed a computational simulation of the cardiopulmonary system to allow lung heterogeneity to be quantified using data solely derived from the IST. Then, the method to quantify lung heterogeneity using two IST tracer gas frequencies (180 and 60 s) was introduced and used in lung simulations and animal models. Thirteen anaesthetized pigs were studied with the IST both before and after experimental lung injury (saline-lavage ARDS model). The deadspace volume was compared between the IST and the SF6 washout method. Main results: The IST could measure lung heterogeneity using two tracer gas frequencies. Furthermore, the value of IST ventilation heterogeneity in ARDS lungs was higher than in control lungs at a positive end-expiratory pressure of 10 cmH2O (area under the curve = 0.85, p < 0.001). Values for the deadspace volume measured by the IST have a strong relationship with the measured values of SF6 (9 ml bias and limits of agreement from ?79 to 57 ml in control animals). Significance: The IST technique has the potential for use in the identification of ventilation and perfusion heterogeneity during ventilator support. ? 2020 Institute of Physics and Engineering in Medicine
Subjects
Mammals
Sulfur hexafluoride
Ventilation
Acute respiratory distress syndrome
Dead space
High rate
In-control
Inspired sinewave test
Lung heterogeneity
Lung simulation
Sine wave test
Tracer gas
Biological organs
animal
artificial ventilation
human
lung
lung function test
lung volume
pig
positive end expiratory pressure ventilation
respiratory distress syndrome
tidal volume
Animals
Humans
Lung
Lung Volume Measurements
Positive-Pressure Respiration
Respiration, Artificial
Respiratory Distress Syndrome
Respiratory Function Tests
Swine
Tidal Volume
SDGs
Type
journal article