Cardiorespiratory physiological perturbations after acute smoke-induced lung injury and during extracorporeal membrane oxygenation support in sheep

Abstract

<jats:title>Abstract</jats:title><jats:sec><jats:title>Background</jats:title><jats:p>Numerous successful therapies developed for human medicine involve animal experimentation. Animal studies that are focused solely on translational potential, may not sufficiently document unexpected outcomes. Considerable amounts of data from such studies could be used to advance veterinary science. For example, sheep are increasingly being used as models of intensive care and therefore, data arising from such models must be published. In this study, the hypothesis is that there is little information describing cardiorespiratory physiological data from sheep models of intensive care and the author aimed to analyse such data to provide biological information that is currently not available for sheep that received extracorporeal life support (ECLS) following acute smoke-induced lung injury.</jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p>Nineteen mechanically ventilated adult ewes undergoing intensive care during evaluation of a form of ECLS (treatment) for acute lung injury were used to collate clinical observations. Eight sheep were injured by acute smoke inhalation prior to treatment (injured/treated), while another eight were not injured but treated (uninjured/treated). Two sheep were injured but not treated (injured/untreated), while one received room air instead of smoke as the injury and was not treated (placebo/untreated). The data were then analysed for 11 physiological categories and compared between the two treated groups.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>Compared with the baseline, treatment contributed to and exacerbated the deterioration of pulmonary pathology by reducing lung compliance and the arterial oxygen partial pressure to fractional inspired oxygen (PaO<jats:sub>2</jats:sub>/FiO<jats:sub>2</jats:sub>) ratio. The oxygen extraction index changes mirrored those of the PaO<jats:sub>2</jats:sub>/FiO<jats:sub>2</jats:sub> ratio. Decreasing coronary perfusion pressure predicted the severity of cardiopulmonary injury.</jats:p></jats:sec><jats:sec><jats:title>Conclusions</jats:title><jats:p>These novel observations could help in understanding similar pathology such as that which occurs in animal victims of smoke inhalation from house or bush fires, aspiration pneumonia secondary to tick paralysis and in the management of the severe coronavirus disease 2019 (COVID-19) in humans.</jats:p></jats:sec>

Cardiorespiratory physiological perturbations after acute smoke-induced lung injury and during extracorporeal membrane oxygenation support in sheep

“…A systematic approach was developed for processing the data. (All raw and processed data are available as Underlying data and can be downloaded at http://www.doi.org/10.5061/dryad.3r2280gd5 18 )…”

“…In order to obtain high-quality cardiorespiratory monitoring data, the instrumentation of the sheep was undertaken to acquire and derive the following physiological parameters using established standard methods at defined timepoints: core body temperature (T), pO 2 , SpO 2 , alveolar–arterial oxygen gradient P(A-a)O 2 , PaO 2 /FiO 2 ratio, end-tidal carbon dioxide concentration (etCO 2 ), heart rate (HR), arterial blood pressure (BP) (systolic and diastolic), mean arterial BP (MAP), pulmonary artery pressure (PA) (systolic and diastolic), mean pulmonary artery pressure (MPAP), central venous pressure (CVP), pulmonary artery occlusion pressure (PAOP), mixed venous oxygen saturation (SvO 2 ), stroke volume (SV), continuous cardiac output (CCO), cardiac index (CI), systemic vascular resistance (SV), systemic vascular resistance index (SVRI), pulmonary vascular resistance index (PVRI), left ventricular stroke work index (LVSWI), right ventricular stroke work index (RVSWI), coronary perfusion pressure (CPP), arterial oxygen content (CaO 2 ), and oxygen delivery index (O 2 EI). (These methods are detailed in data files, available as Underlying data , which can be downloaded at http://www.doi.org/10.5061/dryad.3r2280gd5 18 ).…”

“…A systematic approach was developed for processing the data. (All raw and processed data are available as Underlying data and can be downloaded at http://www.doi.org/10.5061/dryad.3r2280gd5 18 ) Experimental procedures Critical care of animals, VV ECMO setup and physiological data acquisition. The details of animal selection, care, and pre-anaesthetic processes; anaesthesia technique; airway access and ventilation; instrumentation for VV ECMO; haemodynamic monitoring; respiratory monitoring; temperature, fluids, vasoactive drug administration, and electrolyte management; blood collection; physiological data acquisition; and the technique for euthanasia of the sheep after the experiments have previously been described in a detailed protocol 1 .…”

“…The right jugular vein was cannulated both proximally and distally with single lumen central lines to aid insertion of return and access ECMO cannulas, respectively. All animals were intubated and received mechanical ventilation as previously described 1 18 ).…”

“…Manually acquired observations at specifically designated timepoints were recorded and extracted as detailed in the Underlying data, filed at http://www.doi.org/10.5061/ dryad.3r2280gd5 18 . These timepoints were at baseline (soon after instrumentation of the sheep), smoke injury, 5 min post smoke injury, 1 hour post-smoke injury.…”