Non-invasive haemodynamic measurements with Nexfin predict the risk of hypotension following spinal anaesthesia.

Abstract

Unfavourable circulatory system conditions have been observed in many patients with spinal anaesthesia. The most frequent symptoms include a decrease in blood pressure and, less frequently, bradycardia. The appearance of unfavourable consequences of spinal anaesthesia might be related to the initial status of the patient's circulatory system. The aim of this study was to establish the possibility of predicting unfavourable circulatory consequences (hypotension, bradycardia) following spinal anaesthesia, based on non-invasive haemodynamic assessment with a Nexfin device. This prospective study included 100 18-60-year-old ASA I or II planned spinal anaesthesia patients. The initial hemodynamic parameters were assessed with a Nexfin monitor. Anaesthesia was performed with 3-3.5 mL of a 0,5% hyperbaric bupivacaine solution. Within 20 min after the administration of anaesthesia, the arterial blood pressure values, heart rate, sensory blockade level, and motoric blockade level were recorded in 5-min intervals. Hypotension was classified by a decrease of SAP < 90 mm Hg and/or the decrease of the SAP ≥ 20% initial value. Logistic regression was used to determine the independent predictors of hypotension resulting from a spinal blockade. The development of hypotension and bradycardia was observed in 39 and 2%, respectively, of the patients. The patients who developed hypotension differed significantly from those who did not develop this symptom, with the main difference being the body mass and the assessment on the ASA scale. The patients who developed hypotension after spinal anaesthesia differed significantly in the initial hemodynamic parameters (SAP, MAP, SVRI). The following two independent risk factors for hypotension were isolated: the mean arterial pressure (OR 1.04; 95% CI: 1.005-1.076) and the systemic vascular resistance index (OR 1.109; 95% CI: 1.021-1.204). Nexfin-based non-invasive haemodynamic monitoring might be helpful in the identification of individuals with a high risk of hypotension following spinal blockade.