Systematic Review Article: Intraoperative Focused Cardiac Ultrasound for Assessment of Hypotension: A Systematic Review

INTRODUCTION

The use of focused cardiac ultrasound (FoCUS), which can be performed by non-cardiologists with proper training for cardiovascular evaluation, has gained acceptance in the emergency department (ED) and intensive care unit (ICU). Following acceptance by the ED and ICU communities, there has been increasing interest to incorporate this modality into the perioperative area.

This systematic review of the literature was done to assess the utility of intraoperative FoCUS for diagnosis and management of unexplained hypotension in patients undergoing noncardiac surgery.

METHOD

Study Design and Literature Search

A computerized search of electronic databases PubMed, MEDLINE (Ovid), EMBASE, Cochrane CENTRAL, Scopus, CINAHL, and WHO PAHO (VHL) was performed since the beginning date of databases to the search date.

The following terms were used in various combinations: “transthoracic echocardiography” (“TTE”), “perioperative care,” “intraoperative care,” “assessment,” “cardiac,” “ultrasound,” “diagnosis,” “point-of-care,” “hemodynamic monitoring,” “noncardiac surgery,” “low left ventricular ejection fraction,” “intracardiac air,” “thrombus,” “pulmonary embolus,” “left Segmental Wall Motion Abnormality,” “pulmonary embolism,” “aortic valve disease,” “mitral valve disease,” “right ventricular failure,” “pericardial effusion,” “left ventricular outflow tract obstruction,” and “systolic anterior motion of the mitral valve.”

Selection Criteria

Two reviewers independently reviewed all citations. The Population, Intervention, Comparison, and Outcomes (PICO) framework was used to determine selection criteria focused to answer the main research questions:

1. Can FoCUS examination be performed intraoperatively during episodes of unexplained hypotension?
2. Can anesthesiologist with the aid of FoCUS determine the cause of the unexplained hypotension and guide corrective intervention?

RESULTS

Of the total of 2227 identified unique citations, 2200 studies were discarded due to not meeting the inclusion criteria. Of the twenty-seven studies that were selected for full-text assessment for final eligibility, eighteen were excluded for not meeting inclusion criteria.

Of the total of 255 patients who underwent intraoperative FoCUS for unexplained hypotension, in 228 the cause of hypotension was made with FoCUS.

The most commonly encountered diagnoses were hypovolemia, right ventricular failure and left ventricular failure/low ejection fraction. Other diagnoses included vasodilation, segmental wall motion abnormalities, pulmonary hypertension, and pericardial effusion. A total of 137 changes in anesthetic management derived from the results of the intraoperative FoCUS were made; though, not all the studies reported or specified such changes. From those studies that report changes in anesthetic management, the most common ones were administration of vasoactive drugs and fluid management.

DISCUSSION

This systematic review of intraoperative FoCUS during episodes of unexplained hypotension for patients undergoing noncardiac surgery found a high feasibility rate of adequate echocardiographic image acquisition, and the ability to determine the cause of hypotension and guide-corrected intervention.

The use of ultrasound within the practice of anesthesia has been confined mostly to vascular access and nerve blockade. TTE has been a key tool of the cardiology practice, but given its noninvasive nature and wide equipment availability, it has gained an expanded role in the perioperative setting, critical care and the ED. The lack of formal training in FoCUS continues to be the main obstacle for the implementation of such skill into anesthesia residency training as clinical competency. As the number of anesthesiology practitioners with FoCUS training continues to grow, studies describing its role in the perioperative setting and its overall utilization are expected to increase. The ultimate decision in regard to the appropriate diagnostic tool to be used, in the case of an intraoperative episode of unexplained hypotension (FoCUS versus TEE), should be made in a case-by-case basis guided by patient and procedure factors.