Variability in Adequacy of Ventilation during Transport of Cardiac Surgery Patients: A Cohort Study

Abstract

Inadequate ventilation of intubated patients during transport from the operating theatre to the intensive care unit with attendant hypercarbia may adversely affect haemodynamics. In a retrospective observational study, we assessed the incidence of inadequate ventilation during transport from the operating theatre to the intensive care unit in 99 consecutive cardiac surgery patients admitted to our university tertiary hospital. Demographic, clinical, arterial blood gas and haemodynamic measurements were made on arrival in the intensive care unit after cardiac surgery. The relationships between arterial carbon dioxide tension (P a CO 2), mean pulmonary artery pressure (MPAP) and other relevant haemodynamic variables were explored. Overall, hypocarbia (P a CO 2 <35 mmHg) occurred in 18.2% of patients, while 28.3% of patients had hypercarbia (P a CO 2 >45 mmHg). Pulmonary hypertension was common, with nearly half of the cohort having MPAP ≥25 mmHg and 17.2% ≥30 mmHg. However, there was no association between P a CO 2 and MPAP (R 2 =0.0076, P=0.39). Contrary to expectation, neither hypercarbia nor high MPAP were associated with measured adverse outcomes, although this may have been because we studied an insufficient number of patients with extreme values. Associations of higher MPAP, which would be expected to compromise cardiovascular status, included acidaemia, hypoxia and the requirement for noradrenaline. These factors define a group of high-risk patients who should receive particular attention and who should be the focus of future studies.

Carbon dioxide levels of ventilated adult critically ill post-operative patients on arrival to the intensive care unit

“…This finding shows that although there was an increase in the PaCO 2 , it remained within acceptable levels, suggesting that manual ventilation with an MRB at CHBAH may not be injurious as described in some studies. [13,14,21] The results of this study are consistent with studies by Rajasekaram et al [22] and O'Brien et al, [23] who found that there was no clinical difference in the patients who were manually ventilated compared with those who were mechanically ventilated, despite there being a statistically significant change in the PaCO 2 and expired end-tidal CO 2 , respectively.…”