The effects of CO2-insufflation with 5 and 10 mmHg during thoracoscopy on cerebral oxygenation and hemodynamics in piglets: an animal experimental study.

OBJECTIVE: To evaluate the effect of CO2-insufflation with 5 and 10 mmHg on cerebral oxygenation and hemodynamics in neonates.

BACKGROUND: An increasing percentage of surgical interventions in neonates are performed by minimal invasive techniques. Recently, concerns have been raised regarding a decrease of cerebral oxygenation in neonates during thoracoscopy as a result of CO2-insufflation.

METHODS: This was an animal experimental study. Piglets were anesthetized, intubated, ventilated, and surgically prepared for CO2-insufflation. Insufflation was done with 5 or 10 mmHg CO2 during 1 h. Arterial saturation (SaO2), heart rate (HR), mean arterial blood pressure (MABP), and cerebral oxygenation (rScO2) were monitored. CFTOE, an estimator of cerebral oxygen extraction ((SaO2 - rScO2)/SaO2)), was calculated. Arterial blood gases were drawn every 15': pre (T0), during (T1-T4) and after CO2-insufflation (T5).

RESULTS: Ten piglets (4 kg) were randomized for 5 (P5) and 10 (P10) mmHg CO2-insufflation. Two P10 piglets needed resuscitation after insufflation, none P5. Linear mixed-effect modeling of paCO2, pH, and SaO2 showed that values were dependent on time and time squared (p < 0.001) but were not different between the 5 and 10 mmHg groups. Analysis demonstrated significant changes over time in heart rate and MABP between the 5 and 10 mmHg groups, with a significant higher heart rate and lower blood pressure in the 10 mmHg group (p < 0.001). For rScO2 and cFTOE, no group differences could be demonstrated, but a significant effect of time was found: rScO2 increased and cFTOE decreased (p < 0.001).

CONCLUSIONS: Insufflation of CO2 during thoracoscopy with 10 mmHg caused more severe hemodynamic instability and seems to be related with a decrease of cerebral perfusion as represented by a higher oxygen extraction. CO2-insufflation of 5 mmHg for thoracoscopy seems to have no adverse effects on cerebral oxygenation.