Randomised Controlled Trial to Evaluate the Reno-protective Benefits of Remote Ischaemic Preconditioning in Patients Undergoing Infrainguinal Peripheral Angioplasty

Ischaemic preconditioning is an endogenous mammalian mechanism whereby a brief period of ischaemia and reperfusion confers resistance to subsequent prolonged ischaemic insults. First observed in the canine heart, subsequent investigators noted that brief ischaemia in remote organs e.g. skeletal muscle, induced protection in key central organs e.g. the heart. This remote ischaemic preconditioning (RIPC) does not require direct interference with the target organs' blood supply. It can be induced using blood pressure cuffs to produce brief episodes of upper limb ischaemia and reperfusion and confers protection upon numerous organs simultaneously. RIPC reduces myocardial injury following aortic aneurysm repair, cardiac surgery and angioplasty. It also reduces adverse ischaemic events up to six months following percutaneous coronary intervention, implying some medium-term effect.

To date ischaemic conditioning has been applied primarily to the heart however animal studies have shown pre conditioning to offer renal protection.

Fikret et al in 2012 in the Renal Protection Trial demonstrated a protective benefit with RIPC from the development of CIN in high risk patients undergoing elective coronary angiography.Whittaker and Przyklenk in 2011 explored this concept retrospectively using data from patients who had undergone emergency angioplasty for ST elevation myocardial infarction. The original trial was a RCT which examined the protective effect of postconditioning on myocardial ischemia. The authors retrospectively examined if study patients treated with multiple coronary balloon inflations had better renal function than patients not exposed to this remote conditioning. They concluded that patients in the conditioning group received 25% more contrast volume than the control group and showed no decline in renal function as demonstrated by examination of glomular filtration rate at day 3 post procedure in comparison to the control group which saw a significant decline in renal function. The need for contrast-based procedures is rising, with increasing numbers of patients undergoing endovascular procedures, as is the incidence of postcontrast renal failure, which has a reported mortality of 34%. The potential use of RIPC therefore to reduce the risk of kidney damage needs further investigation in a prospective study and the PAD patient group who are routinely exposed to contrast administration in angiography are an ideal study group.