Risk Factors for Hypotension after Anaesthesic Induction and Early Intraoperative Hypotension

Intraoperative hypotension should be differentiated with respect to the different underlying causal mechanisms. Post-induction hypotension is defined as arterial hypotension occurring during the first 20 minutes after induction of anaesthesia and early intraoperative hypotension is arterial hypotension during the first 30 minutes of surgery.

The aim of our study is to evaluate the incidence of intraoperative hypotension during surgery under general anaesthesia in a patient population and the factors influencing its occurrence.

Materials and Methods: This is a prospective study, carried out over a period of 4 months on 154 patients scheduled for surgery under general anaesthesia at the Military Hospital of Instruction Mohammed V in Rabat. We collected the following information : age, sex, ASA score, body mass index, comorbidities, drug intake and type of surgery. The occurrence or not of post induction hypotension and early intraoperative hypotension.

Results: The mean age of the patients in our case series was 58.5 ± 12 years. The sex ratio was 1.4 with a predominance of males. ASA I and II status were predominant. In univariate analysis: advanced age, the existence of chronic arterial hypertension and the decrease in systolic blood pressure before induction were factors favouring the occurrence of intraoperative hypotension. In multivariate analysis: We found that these 3 factors were independently related to the occurrence of intraoperative hypotension.

Conclusion: We found that lower pre-induction systolic blood pressure, older age and comorbidity such as hypertension are factors independently associated with post-induction and early intraoperative hypotension. We believe that this will allow preventive optimisation of the risk through early implementation of continuous haemodynamic monitoring and adequate therapeutic intervention.