REDUCTION OF CEREBRAL OXYGEN SATURATION DURING REWARMING FROM HYPOTHERMIC CARDIOPULMONARY BYPASS

Background: This study aimed to examine the effect of pulsatile flow pattern on tissue perfusion, particularly cerebral tissue perfusion, at pre-determined intervals during CPB, as well as its effects on postoperative morbidity and mortality. Methods: This retrospective study included 134 adult patients, who underwent cardiac surgery with cardiopulmonary bypass (CPB). Patients were grouped based on the flow pattern used during CPB: non-pulsatile CPB group (N = 82) and pulsatile CPB group (N = 52). Cerebral oxygen saturation, arterial pH and arterial lactate levels were measured at four time points, during the operation and the 2 groups were compared with regard to changes over time as well as differences in postoperative outcomes. Results: The 2 groups were similar, in terms of mean values and intraoperative changes in cerebral oxygen saturation and arterial pH. Non-pulsatile CABG group had significantly higher arterial lactate levels over the measurement period, which was not affected by the timing of the measurements. Postoperative drainage, duration of ventilation and duration of hospital stay significantly were higher and postoperative blood urea nitrogen significantly was lower in the non-pulsatile CPB group. Other postoperative outcomes were similar across the groups. Conclusion: Findings of this study do not support the superiority of pulsatile flow pattern during CPB, in terms of cerebral oxygen saturation or postoperative mortality/morbidity. Further and larger comparative studies are warranted before pulsatile blood flow pattern can be established as a routine clinical method.

Download Full-text

Utility of Cerebral Oxymetry for Assessing Cerebral Arteriolar Carbon Dioxide Reactivity during Cardiopulmonary Bypass

The Heart Surgery Forum ◽

10.1532/hsf98.2014319 ◽

2014 ◽

Vol 17 (3) ◽

pp. 169 ◽

Cited By ~ 3

Author(s):

Cem Ariturk ◽

Murat Okten ◽

Zehra Serpil Ustalar Ozgen ◽

Esin Erkek ◽

Pinar Uysal ◽

...

Keyword(s):

Carbon Dioxide ◽

Cardiopulmonary Bypass ◽

Oxygen Saturation ◽

Flow Rate ◽

Gas Flow ◽

Cerebral Oxygen Saturation ◽

Arterial Oxygen ◽

Cerebral Oxygen ◽

Gas Flow Rate ◽

Anesthetic Induction

Background: Our study evaluated changes in cerebral arterial oxygen saturation (rSO2) during cardiopulmonary bypass (CPB) that were caused by changes in arterial carbon dioxide tension (PaCO2).Methods: A group of 126 patients undergoing routine, elective, first-time coronary artery bypass graft surgery (CABG) was entered into a prospective study using bilateral near-infrared spectroscopy (NIRS) before anesthetic induction (T1), after anesthetic induction (T2), and continuing at 5-minute intervals during moderate hypothermic (32�C) CPB. Pump flows were set at 2.5 L/min/m2 and adjusted to maintain mean arterial pressure (MAP) within 10 mmHg of the MAP recorded at the initial fifth minute of CPB (T3). Thirty-two patients were excluded from data collection because MAP could not be stabilized within the target range of 60-90 mmHg. In the remaining 94 patients, after obtaining steady state flow, MAP, and oxygenation, a trial period of hypocarbia (mean PaCO2 of 30 mmHg) was induced by increasing oxygenator fresh gas flow rate (FGFR) to 2.5 L/min/m2 (T4). A reciprocal period was then measured at reduced FGFR (0.75 L/min/m2) (T5).Results: After 20 minutes of a higher (2.75 L/min/m2) (FGFR), mean PaCO2 decreased from a baseline of 38 � 4 mmHg to 30 � 2 mmHg. This was associated with a parallel decrease (-10�9%) in mixed cerebral oxygen saturation without alteration of mean arterial oxygen tension (PaO2), lactate, MAP, CPB flow, or other parameters implying increased cerebral oxygen extraction.Conclusion: Parallel changes in PaCO2 and rSO2 occur during CPB when other variables remain constant, and are due to the effects of carbon dioxide on cerebral arterioles. Cerebral oxygen saturation measured by NIRS may be a useful indirect measure of PaCO2 when continuous blood gas analysis is not possible during open-heart surgery. Cerebral oximetry values may be useful measurements for setting an optimum gas flow rate through the oxygenator.

Download Full-text