Early and late effects of remote ischemic preconditioning on spirometry and gas exchange in healthy volunteers

Abstract

Purpose: Remote ischemic preconditioning (RIP) may protect remote organs from ischemia-reperfusion-injury (IRI) in surgical and non-surgical patients. There are few data available on RIP and lung function, especially not in healthy volunteers. The null-hypothesis was tested that RIP does not have an effect on pulmonary function when applied on healthy volunteers that were breathing spontaneously and did not experience any intervention. After approval of the Ethics Committee and informed consent of the study subjects, 28 healthy non-smoking volunteers were included and randomized in either the RIP group (n = 13) or the control group (n = 15). In the RIP group, lower limb ischemia was induced by inflation of a blood pressure cuff to a pressure 20 mmHg above the systolic blood pressure. After five minutes the blood pressure cuff was released for five minutes rest. The procedure was repeated three times resulting in 40 min ischemia and reperfusion. Capillary blood samples were taken, and lung function tests were performed at baseline (T1) and 60 min (T2) and 24 h (T3) after RIP. The control group was treated in the same fashion, but the RIP procedure was replaced by a sham protocol.

Results: 60 min after RIP capillary pO₂ decreased significantly and returned to baseline level after 24 h in the RIP group. This did not occur in the control group. Capillary pCO₂, variables of lung function tests and pulmonary capillary blood volume remained unchanged throughout the experiment in both groups.

Conclusion: Oxygenation is impaired early after RIP which is possibly induced by transient ventilation-perfusion inequality. No late effects of RIP were observed. The null hypothesis has to be rejected that RIP has no effect on respiratory variables in healthy volunteers.

Keywords: Diffusion capacity; Gas exchange; Pulmonary capillary volume; Pulmonary function; Remote ischemic preconditioning.