Cardiovascular effects of low-dose spinal anaesthesia as a function of age: An observational study using echocardiography.

BACKGROUND

Spinal anaesthesia (SA) is a widely used technique of regional anaesthesia but hypotension is an adverse effect commonly observed, especially in elderly patients.

OBJECTIVE

The objective of this study was to assess the cardiovascular effects induced by a single injection of a low-dose SA during elective surgery by using transthoracic echocardiography (TTE) and to compare these effects in patients older and younger than 70 years of age.

DESIGN

Observational study.

SETTING

Single centre university hospital.

PATIENTS OR OTHER

PARTICIPANTS

Forty-six patients scheduled for surgery under SA were included in the study (25 patients<70 years and 21 patients ≥ 70 years).

INTERVENTION(S): A cardiologist, blinded to all clinical parameters, interpreted the TTE.

MAIN OUTCOME MEASURES: Two TTEs were performed for each patient: one at baseline before and the second 20 minutes after the placement of the SA.

RESULTS

Sixty-six percent of patients became hypotensive in the ≥ 70 years group whereas no episode of hypotension occurred in the<70 years group (P<0.0001). At baseline (i.e. prior to SA), when compared to younger patients, elderly patients had both a lower E/A ratio (0.8 [0.5-2.1] vs. 1.4 [0.7-1.6], P=0.001) as well as a lower LVEF (50.4% [37.7-72.3] vs. 60.9% [44.8-69.8], P<0.0001). SA in the elderly induced a larger decrease in the cardiac index (CI) (-0.5 L·min(-1)·m(-2) [-0.8 to -0.3] vs. -0.2 L·min(-1)·m(-2) [-0.8-0.1], P<0.0001), LV stroke volume (-8mL [-13-4] vs. -2mL [-14 to -1], P<0.0001) and systemic vascular resistances (SVR) (-2.2 WU [-6.7-0.3] vs. -0.8 WU [-2.3-0.1], P<0.0001).

CONCLUSIONS

Hypotension is more frequent among elderly patients, even after low-dose SA. Known age-related changes in cardiovascular performance, such as impaired myocardial relaxation and decreased systolic function could be responsible for the decrease in cardiac output (CO) and SVR seen in these patients.