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Increased intrathoracic pressure affects cerebral oxygenation following cardiac surgery
Author(s) -
Pedersen Lars M.,
Nielsen Jonas,
Østergaard Morten,
Nygård Eigil,
Nielsen Henning B.
Publication year - 2012
Publication title -
clinical physiology and functional imaging
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.608
H-Index - 67
eISSN - 1475-097X
pISSN - 1475-0961
DOI - 10.1111/j.1475-097x.2012.01138.x
Subject(s) - medicine , oxygenation , anesthesia , mean arterial pressure , hemodynamics , cerebral autoregulation , cardiology , cerebral perfusion pressure , cerebral blood flow , blood pressure , cardiac output , autoregulation , heart rate
Summary Background Cerebral oximetry reflects circulatory stability during surgery. We evaluated whether frontal lobe oxygenation is influenced by a transient increase in intrathoracic pressure as induced by a lung recruitment manoeuvre. Methods Intrathoracic pressure was increased to 40 cm H 2 O for 20 s immediately after cardiac surgery in ten patients (age 64 ± 10 year, mean ± SD ) with frontal lobe oxygenation assessed by near‐infrared spectroscopy and cardiac output by thermodilution. Results The lung recruitment manoeuvre increased arterial O 2 pressure (from 29 ± 15 to 40 ± 12 kP a) with a decrease in mean arterial pressure ( MAP ) (from 69 ± 7 to 55 ± 11 mmHg), cardiac output (from 5·4 ± 0·6 to 5·0 ± 0·7 l min −1 ) and frontal lobe oxygenation (from 68 ± 9 to 60 ± 13%; all P <0·05). A reduction in MAP by more than 15 mmHg caused cerebral desaturation by 10%, the lowest cerebral oxygenation (44%) was with a reduction in MAP by 24 mmHg, and according to multiple linear regression, only MAP predicted cerebral deoxygenation ( P = 0·03). Following the lung recruitment manoeuvre, hemodynamic variables and frontal lobe oxygenation were restored. Conclusions A lung recruitment manoeuvre decreases frontal lobe oxygenation when MAP is low suggesting that with increased intrathoracic pressure, arterial pressure should be kept within the limits of cerebral autoregulation.