Comparison of change in perfusion index during induction of anaesthesia in normotensive and hypertensive patients posted for elective surgery

Perfusion index (PI) is a non-invasive numerical value of peripheral perfusion calculated using infrared spectrum as part of plethysmography waveform processing. It is a simple, cost-effective and non-invasive method of assessing peripheral perfusion determined by the percentage of pulsatile to non-pulsatile blood flow in the extremities that can be continuously and non-invasively obtained from pulse oximeter.

Patients with hypertension are exposed to hemodynamic instability during anaesthesia, which is known to be associated with adverse perioperative outcomes such as acute renal failure or cerebral ischemia. The cause of this hemodynamic instability is that patients with hypertension are exposed to high blood pressure for a long time, leading to anatomical or pathophysiological changes in the hemodynamic systems. These changes make them sensitive to the effects of anaesthetic drugs that frequently cause hypotension. Patients with hypertension may develop significant hypotension after the induction of anaesthesia when the initial sympathetic nervous system response to laryngoscopy and endotracheal intubation which typically increases blood pressure is subsided. Induction of anaesthesia and insertion of Laryngeal mask airway both induce clinically relevant hemodynamic changes in patients. PI reflects the patient’s haemodynamic state. Determining and monitoring the perfusion index pre and post induction helps to predict the haemodynamic instability and timely corrective measures to be applied Hypertensive patients are more prone to develop haemodynamic instability than those without hypertension. There are very few studies comparing the perfusion index in hypertensives and normotensive patients in general anaesthesia. The aim of this study is to compare the change of perfusion index in normotensive and hypertensive adult patients during induction of general anaesthesia posted for elective surgery.