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On‐line measurement of gas‐exchange during cardiac surgery
Author(s) -
Fletcher R.,
Malmkvist G.,
Niklason L.,
Jonson B.
Publication year - 1986
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/j.1399-6576.1986.tb02417.x
Subject(s) - medicine , anesthesia , bypass grafting , airway , artery , surgery , nuclear medicine
This paper describes an on‐line system for continuously monitoring expired CO 2 during controlled ventilation. Signals from a Servo ventilator 900B or C and a CO 2 Analyzer 930 are processed and corrected by the computer to produce a CO 2 single breath test (SBT‐CO 2 ). This is the tracing of expired CO 2 concentration or fraction against expired volume, from which the computer calculates the airway deadspace (V D aw). If a value for arterial PCO 2 is supplied, the computer will calculate the physiological deadspace (V D phys) and the alveolar deadspace (V D alv) for each breath. The system was used to make measurements at four stages during coronary artery by‐pass grafting in 13 male patients. When the sternum was opened there was a 32% increase in V D aw, and the physiological deadspace fraction therefore increased. There were reductions in V D aw after extra‐corporeal circulation and again after sternal suture. By the end of surgery, the alveolar deadspace fraction had increased significantly. V D aw at this stage was smaller than pre‐operatively, and so there was no net change in the physiological deadspace fraction at the end of surgery. Arterial Po 2 was, however, reduced at this stage.