Effects of acute hypercapnia on cognitive function in patients undergoing bronchoscope intervention

There are multiple studies that have revealed that hypercapnia possessed neuroprotection, the conclusive cognitive impacts of permissive hypercapnia in medicine is still unclear.

A total of 102 patients registered for this research work had accomplished cognitive tests; with 64 patients possessing moderate hypercapnia all through bronchoscope intervention (BI). Thirty-six patients completed collection of blood specimens. Every patient underwent the Mini Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA) a day before the surgery (T0), as well as at 7 days (T7). Serum specimens were used to measure levels of S100B, neuron-specific enolase (NSE), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), malondialdehyde (MDA), superoxide dismutase (SOD) prior to the administration of anesthesia (T0), one day (T1) and seven days (T7) after surgery.

In comparison with the preoperative MMSE scores, Group Hypercapnia (Group H) on 7 days after surgery, exhibited a significant increased score (P=0.00). In comparison with the preoperative MoCA scores, Group H on 7 days after surgery exhibited a significant increased score (P=0.00). Meanwhile, the MoCA scores in Group H exhibited considerably higher elevation as compared with that in the Group Control (Group C) (P=0.01). No substantial differences were observed in serum S100B and NSE levels between Group H and Group C (P=0.23, P=0.14). Serum IL-6, TNF-α, SOD and MDA levels shared similarity between two groups.

Mild and moderate hypercapnia augmented cognitive activity with the help of MMSE tests and MoCA tests, whereby the latent reasons were not sure. As suggested by this study, hypercapnia up to 100 mmHg during BI was less likely to affect cognitive function adversely.