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Ventilation/perfusion ratios measured by multiple inert gas elimination during experimental cardiopulmonary resuscitation
Author(s) -
HARTMANN E. K.,
DUENGES B.,
BOEHME S.,
SZCZYRBA M.,
LIU T.,
KLEIN K. U.,
BAUMGARDNER J. E.,
MARKSTALLER K.,
DAVID M.
Publication year - 2014
Publication title -
acta anaesthesiologica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.738
H-Index - 107
eISSN - 1399-6576
pISSN - 0001-5172
DOI - 10.1111/aas.12378
Subject(s) - medicine , cardiopulmonary resuscitation , anesthesia , ventilation (architecture) , perfusion , oxygen , return of spontaneous circulation , ventricular fibrillation , cardiology , inert gas , hypothermia , resuscitation , chemistry , mechanical engineering , organic chemistry , engineering
Background During cardiopulmonary resuscitation ( CPR ) the ventilation/perfusion distribution ( V A /Q ) within the lung is difficult to assess. This experimental study examines the capability of multiple inert gas elimination ( MIGET ) to determine V A /Q under CPR conditions in a pig model. Methods Twenty‐one anaesthetised pigs were randomised to three fractions of inspired oxygen (1.0, 0.7 or 0.21). V A/ Q by micropore membrane inlet mass spectrometry‐derived MIGET was determined at baseline and during CPR following induction of ventricular fibrillation. Haemodynamics, blood gases, ventilation distribution by electrical impedance tomography and return of spontaneous circulation were assessed. Intergroup differences were analysed by non‐parametric testing. Results MIGET measurements were feasible in all animals with an excellent correlation of measured and predicted arterial oxygen partial pressure ( R 2 = 0.96, n = 21 for baseline; R 2 = 0.82, n = 21 for CPR ). CPR induces a significant shift from normal V A /Q ratios to the high V A /Q range. Electrical impedance tomography indicates a dorsal to ventral shift of the ventilation distribution. Diverging pulmonary shunt fractions induced by the three inspired oxygen levels considerably increased during CPR and were traceable by MIGET , while 100% oxygen most negatively influenced the V A /Q . Return of spontaneous circulation were achieved in 52% of the animals. Conclusions V A /Q assessment by MIGET is feasible during CPR and provides a novel tool for experimental purposes. Changes in V A /Q caused by different oxygen fractions are traceable during CPR . Beyond pulmonary perfusion deficits, these data imply an influence of the inspired oxygen level on V A /Q . Higher oxygen levels significantly increase shunt fractions and impair the normal V A /Q ratio.