Preoperative ultrasound guided estimation of subclavian vein diameter changes by passive leg rising to assess the incidence of post-induction hypotension after General anaesthesia in patients of head and neck malignancies: A Prospective Observational Study

Postinduction hypotension can occur during the early phase of anesthesia, typically within 20 minutes after the induction of general anesthesia. Several factors contribute to postinduction hypotension. General anesthetic agents can cause vasodilation, leading to decreased systemic vascular resistance and subsequent hypotension.Reduced blood volume due to inadequate fluid status or preoperative fasting can contribute to the same patient characteristics like age, comorbidities, and medications the patient is taking all may have an effect.Prolonged hypotension during surgery can have significant consequences for patients. Prolonged low blood pressure can impair perfusion to vital organs and may lead to myocardial injury, acute kidney injury, cerebral ischemia etc. So it is of paramount importance to identify the risk groups prior to induction and manage the hypotension judiciously. Pre-induction ultrasonography of IJV was used to predict post-induction hypotension and SCV collapsibility index in deep inspiration has been shown to predict hypotension after induction of GA.

We hypothesize that the subclavian vein diameter changes induced by passive leg rising can be used to estimate intravascular fluid status and can be an indicator of incidence of hypotension after general anaesthesia. Therefore we aim to evaluate the the predictive power of ultrasound guided diameter changes of subclavian vein in the spontaneous breathing PLR position.for post induction hypotension