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Pulmonary vascular reactivity of the newborn pony foal
Author(s) -
DRUMMOND W. H.,
SANCHEZ I. R.,
KOSCH P. C.,
WEBB A. I.
Publication year - 1989
Publication title -
equine veterinary journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.82
H-Index - 87
eISSN - 2042-3306
pISSN - 0425-1644
DOI - 10.1111/j.2042-3306.1989.tb02137.x
Subject(s) - pony , foal , ductus arteriosus , medicine , pulmonary hypertension , cardiac index , pulmonary artery , cardiac output , foramen ovale (heart) , circulatory system , anesthesia , cardiology , vascular resistance , hemodynamics , patent foramen ovale , archaeology , migraine , history
Summary Adult ponies develop pulmonary hypertension at altitude (Bisgard, Orr and Will 1975), but the neonatal response to acute hypoxaemia is unknown. Seven foals aged five days were instrumented with a systemic and a Swan‐Ganz pulmonary artery catheter while anaesthetised and intubated. Cardiac index, pulmonary (PAP) and systemic (SAP) vascular pressures were measured as the foals breathed gas mixtures with F 1 0 2 of 8 to 94 per cent. Because foramen ovale or ductus arteriosus shunts might have altered thermodilution cardiac index measurements in the stressed foals, the ratio, PAP/SAP was calculated to define relative circulatory reactivity. Three foals, two of which were full siblings, had very marked elevation of PAP/SAP from 0.6 to 1.41 at low inspired oxygen tensions. Four different foals attained maximal PAP/SAP of only 0.2 to 0.92 at similarly low oxygen tensions (P<0.0001). Thus, pulmonary vascular reactivity to ventilatory hypoxaemia varied greatly in pony foals of the same age. The exaggerated reactivity in related foals suggested that, as in cattle, a genetic predisposition to develop reactive pulmonary hypertension under hypoxaemic stress may exist.