Haemodynamic adaptation profiles after spinal anaesthesia for caesarean section: an UltraSonic Cardiac Output Monitoring study

Objective. There is scarce data that allows anaesthesiologists to identify patients who may suffer from side effects and hae­modynamic impairment after spinal anaesthesia. To identify baseline characteristics and the trend in haemodynamic vari­ables in patients with poor versus normal adaptation. Poor adaptation was defined as a drop in cardiac index (CI) of at least > 20% after spinal anaesthesia. We also sought to study if MAP/HR and SVR follow the same trend in the ‘poor adapta­tion’ and ‘normal adaptation’ groups.
Materials and Methods. Retrospective observational study. USCOM measurements were performed in seven different moments analysing key haemodynamic parameters: CO, SVR, SV, MAP, HR, SMII, PKR. Spinal anaesthesia dosage was stan­dardized, and no preload or preventive ephedrine were ad­ministered. Comparisons between groups by ANOVA.
Results. 54 women were enrolled. In the poor adaption group BMI was significantly higher and IUGR foetuses were more frequent. SMII dropped significantly, CI had a significant drop before returning to baseline. Conversely, in the normal adap­tation group CI increased without dropping until the end of the surgery, with SVR and PKR showing a significant drop. MAP was reduced until the end of surgery in both groups. Only 52.4% of patients with a MAP/HR ratio < 1.1 had SVR < 1,300 dynes × sec/cm5.
Conclusions. Patients with normal adaptation had the great­est variation of haemodynamic parameters to compensate anaesthesia. MAP was not sufficient to describe haemody­namics variation and MAP/HR cannot be a substitute pa­rameter for SVR to identifying patients with vasodilated circulation.