Preoperative ultrasonographic evaluation of inferior venacava collapsibilty as a predictor for hypotension associated with general anaesthesia: An Observational study.

Hypotension is common during surgery in patients under anaesthesia  and may cause organ under perfusion and ischemia  . After induction of general anaesthesia, patients are at particular risk of developing hypotension because of the cardiovascular depressant and vasodilatory effects of anaesthetic agents, as well as lack of surgical stimulation. Furthermore, patients may have preexisting hypovolemia resulting from dehydration and impaired compensatory responses, which increase the risk  . Predictors of hypotension after induction of anaesthesia include American Society of Anaesthesiologists physical status (ASA) III and IV, baseline mean arterial pressure lower than 70 mmHg, age more than 50 yr, use of propofol, and high fentanyl dose  . Heart rate (HR) variability can predict hypotension and bradycardia after induction of anaesthesia  . However, the role of preoperative volume status in the development of hypotension after induction has not been assessed fully. Assessing intravascular volume status is a challenge for clinicians. Traditional static parameters such as central venous pressure have been criticized for invasiveness and lack of accuracy  . A number of dynamic parameters that assess volume status have been recommended recently . Ultrasound measurements of inferior vena cava (IVC) diameter with respiration, which include (1) maximum diameter of the IVC (dIVCmax) at the end of expiration during spontaneous respiration and (2) collapsibility index (CI), have been recommended as rapid and noninvasive methods for estimating volume status. These parameters have been proposed as repeatable and easily obtainable parameters by operators with little experience in echocardiography. Therefore, we hypothesize that preoperative dIVCmax and its respiratory variation, that is, CI, could predict the incidence of hypotension after induction of general anaesthesia. The aim of the research is to ultrasonographic evaluation of the inferior vena cava collapsibility for detection of hypotension following general anaesthesia.