TEE for Noncardiac Surgery

TEE for Noncardiac Surgery
Ben Sommer1
Albert C. Perrino, Jr2
Scott T. Reeves2
1OUTLINE AUTHOR
2ORIGINAL CHAPTER AUTHORS
▪ KEY POINTS
  • The value of transesophageal echo cardiography (TEE) during noncardiac surgery is well established.
  • The most common indications for TEE during noncardiac surgery are as a rescue technique in the hemodynamically unstable patient and as a monitor in patients at risk for cardiovascular complications.
  • Assessments of preload and systolic function are the most valued functions of intraoperative TEE during noncardiac surgery.
  • Quantitative assessments of ventricular function are preferred to visual estimates.
  • The increasingly elderly and high-risk patient population undergoing vascular, laparoscopic, orthopedic, neurosurgical, and hepatic procedures warrants expanded use of TEE.
I. INTRODUCTION
  • Limited availability of echocardiographic systems and clinicians trained in TEE initially slowed the growth of TEE in noncardiac procedures.
  • TEE can provide rapid diagnosis in a patient not responding to standard therapies. This warrants TEE availability to most anesthetized patients.
II. INDICATIONS
  • Indications for TEE remain only partially defined.
  • Well-conducted outcome trials examining the effectiveness of TEE during noncardiac surgery are lacking and unlikely to be forthcoming.
  • The lack of supporting evidence is often owing to the absence of relevant studies rather than to existing evidence of ineffectiveness.
  • Category I indication (supported by strong evidence or expert opinion): intraoperative evaluation of acute persistent and life-threatening hemodynamic disturbances in which ventricular function and its determinants are uncertain and have not responded to treatment.
  • Category II indication (supported by weaker evidence and expert consensus): perioperative use in patients with increased risk of hemodynamic disturbances.
  • Categories I and II together remain by far the most frequent reasons for the use of intraoperative TEE during noncardiac surgery.
  • TEE has been shown to change intraoperative management, either surgical or medical, in up to 40% of patients. These changes include changes in medical therapy, confirming or invalidating a diagnosis, unplanned surgical reinterventions, substitution for a pulmonary artery (PA) catheter, and positioning of intravascular devices.1,2,3,4
  • TEE has value both as a diagnostic tool and as an intraoperative monitor over and above that achievable with radial and pulmonary arterial catheters.
  • TEE has value in monitoring and detecting myocardial ischemia, fluid status, and global ventricular function.
III. APPROACH
  • Optimization of ventricular performance during noncardiac surgery
  • Assessing preload
  • Assessing stroke volume (SV)
  • Echocardiographic techniques for SV measurement
  • Right heart SV calculation
  • Alternative approaches to optimizing fluid status
  • Completing the exam
IV. OPTIMIZATION OF VENTRICULAR PERFORMANCE DURING NONCARDIAC SURGERY
  • The principles underlying optimization of ventricular performance using TEE remain guided by the Frank-Starling relationship.5,6
  • The value of the Frank-Starling relationship is that it provides and interactive approach to optimizing the relationship between preload and systolic output.
  • The necessary parameters for deriving Frank-Starling relationship, preload and SV, are easily monitored intraoperatively with TEE.
A. Assessing preload (Fig. 16-1)
  • TEE is superb for both quantitative assessment and monitoring the adequacy of preload throughout surgery.7,8,9,10,11
  • The most popular approach to measure left ventricular (LV) preload is by determination of the LVEDA from the TG midpapillary SAX view.
  • LVEDA has been validated to accurately track changes in intraoperative fluid status and is simply calculated from manual tracings of still frame echoes at end-diastole.
  • Normal values for LVEDA are typically 12 to 18 cm2.
▪ FIGURE 16.1
B. Assessing stroke volume
  • Doppler techniques are preferred for SV determination.
  • SV is calculated as the time-velocity integral (TVI) multiplied by the cross-sectional area (CSA) of the conduit:
    SV = TVI × CSA
  • Cardiac output is determined from the product of SV and heart rate.
  • Echocardiographic techniques for SV measurement:
  • SV and CO measurements are best measured at the left ventricular outflow tract (LVOT) or at the aortic valve.12,13,14
  • Several studies have confirmed that the CO measurement obtained by TEE compare favorably to those obtained by thermodilution.13,14
  • LVOT or transaortic flows are most reliably obtained from the TG LAX and the deep TG LAX views.
  • CSA of the LVOT is best obtained from the ME LAX view.
  • CSA is calculated from a measurement of the LVOT diameter as
    CSAlvot = II (D/2)2
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May 26, 2016 | Posted by in CARDIOLOGY | Comments Off on TEE for Noncardiac Surgery

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