[Continuous spinal anesthesia and pulmonary arterial hypertension]

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.

Optimal perioperative management of arterial blood pressure

Perioperative blood pressure management is a key factor of patient care for anesthetists, as perioperative hemodynamic instability is associated with cardiovascular complications. Hypertension is an independent predictive factor of cardiac adverse events in noncardiac surgery. Intraoperative hypotension is one of the most encountered factors associated with death related to anesthesia. In the preoperative setting, the majority of antihypertensive medications should be continued until surgery. Only renin-angiotensin system antagonists may be stopped. Hypertension, especially in the case of mild to moderate hypertension, is not a cause for delaying surgery. During the intraoperative period, anesthesia leads to hypotension. Hypotension episodes should be promptly treated by intravenous vasopressors, and according to their etiology. In the postoperative setting, hypertension predominates. Continuation of antihypertensive medications and postoperative care may be insufficient. In these cases, intravenous antihypertensive treatments are used to control blood pressure elevation.