Timothy Maus

Cardiac Output Determination From Endotracheally Measured Impedance Cardiography: Clinical Evaluation of Endotracheal Cardiac Output Monitor

OBJECTIVES To evaluate the accuracy, precision, and trending of a new endotracheally sourced impedance cardiography-based cardiac output (CO) monitor (ECOM; ConMed Corp, Irvine, CA). SETTING Two university hospitals. PARTICIPANTS Thirty patients scheduled for elective coronary artery bypass graft (CABG) surgery. INTERVENTIONS All patients received a pulmonary artery catheter (PAC), arterial catheter, endotracheal CO monitor (ECOM), endotracheal intubation, and transesophageal echocardiographic monitoring. ECOM CO was compared with CO measured with pulmonary artery thermodilution, and left ventricular CO measured with transesophageal echocardiography. MEASUREMENTS One hundred forty-five pairs of triplicate CO measurements using intermittent bolus pulmonary artery thermodilution (TD) and ECOM were compared at 5 distinct time points: postinduction, postinduction passive leg raise, poststernotomy, post-CABG completion, and post-chest closure. Eighty-seven pairs of triplicate CO measurements using transesophageal echocardiography were obtained at 3 time points: postinduction, post-CABG completion, and post-chest closure and compared with ECOM- and PA-derived CO measurements. The measurements at each time point were compared by using Bland-Altman and polar plot analyses. RESULTS The mean CO ranged from 2.16 to 9.41 L/min. ECOM CO, compared with TD CO, revealed a bias of 0.02 L/min, 95% limits of agreement of -2.26 to 2.30 L/min, and a percent error of 50%. ECOM CO showed trending with TD CO with 91% and 99% of values within 0.5L/min and 1 L/min limits of agreement, respectively. ECOM CO, compared with TEE CO, revealed a bias of -0.25 L/min, 95% limits of agreement of -2.41 to 1.92 L/min, and a percent error of 48%. ECOM CO showed trending with TEE CO with 83% and 95% of values within 0.5L/min and 1 L/min limits of agreement, respectively. CONCLUSION ECOM CO shows an acceptable bias with wide limits of agreement and a large percent error when compared with TD CO or TEE CO; however, it shows acceptable trending of CO to both modalities in patients undergoing cardiac surgery. Further studies are required to evaluate ECOM in other patient populations and clinical situations.

Case 13--2014: Management of pulmonary hemorrhage after pulmonary endarterectomy with venovenous extracorporeal membrane oxygenation without systemic anticoagulation.

From the *University of California, San Diego, Thornton Hospital, †University of Chicago, Chicago, IL, ‡University of Pittsburgh, Pittsburgh, PA; and §Duke University Medical Center, Durham, NC. Address reprint requests to Brett Cronin, MD, Dept. of Anesthesiology, University of California, San Diego, Thornton Hospital, 9300 Campus Point Drive #7770, La Jolla, CA 92037. E-mail: bcronin@ ucsd.edu

Multidisciplinary Approach to Transvenous Lead Extraction: A Single Center’s Experience

OBJECTIVE To evaluate the success and complication rates of a single centers multidisciplinary approach to transvenous lead extraction. SETTING One university hospital. PARTICIPANTS One hundred ninety-five patients scheduled for transvenous lead extraction. INTERVENTIONS A multidisciplinary approach to transvenous lead extraction involving cardiac surgery, electrophysiology, perfusion, and cardiac anesthesiology. MEASUREMENTS AND MAIN RESULTS A case series of 351 lead extractions performed in 195 patients over a 42-month period. Indications, success rates, and complication rates were tracked and retrospectively evaluated and reported. Indications for lead extraction included 53.3% because of lead malfunction, 36.9% because of infection, with the remaining 9.7% from other categories such as venous stenosis. The lead extraction rate was 99.7%, with complete removal in 97.7%. The overall major complication rate was 3.08%. After an initial 1-year period of performing lead extractions, the overall major complication rate reduced to 1.23%. CONCLUSIONS Transvenous lead extraction generally is a safe procedure, but not without complications. A multidisciplinary approach involving cardiac surgery, electrophysiology, and cardiac anesthesiology allows for successful management and the ability to rapidly manage major complications.

Pulmonary Artery Catheter Placement Using Transesophageal Echocardiography

OBJECTIVE To assess the feasibility of pulmonary artery catheter placement using transesophageal echocardiography inclusive of a description of the technique. DESIGN A prospective, proof-of-concept study. SETTING Single university hospital. PARTICIPANTS Twenty patients with chronic thromboembolic pulmonary hypertension scheduled for pulmonary thromboendarterectomy. INTERVENTIONS Pulmonary artery catheters were placed in 20 patients solely by transesophageal echocardiographic guidance. MEASUREMENTS AND MAIN RESULTS Placement of the pulmonary artery catheter in the pulmonary artery with transesophageal echocardiography guidance in fewer than 10 minutes was considered successful placement. The time to placement was measured from advancement of the pulmonary artery catheter in the superior vena cava (20 cm) to a final location at the junction of the right pulmonary artery and main pulmonary artery. All 20 pulmonary artery catheters were placed successfully using transesophageal echocardiography guidance and the median time to placement was 43 seconds. In 9 of the 20 patients (45%), the catheter was placed successfully on the first attempt without any adjustments. However, in 9 others (45%), the catheter required manipulation under transesophageal echocardiography vision. In 3 patients (15%), the pulmonary artery catheter was observed to be coiled in the right atrium and in 1 instance (5%) manipulation of the catheter in the right ventricle was required to enter the outflow tract. CONCLUSIONS Transesophageal echocardiography is a viable adjunctive method to conventional pressure waveform placement of pulmonary artery catheters in potentially difficult patients.

Intraoperative Three Dimensional Echocardiography Derived Right Ventricular Volumetric Analysis in Chronic Thromboembolic Pulmonary Hypertension Patients Before and After Pulmonary Thromboendarterectomy

OBJECTIVES To assess the change in 3-dimensional (3D) echocardiography-derived right ventricular volumes before and after pulmonary thromboendarterectomy (PTE) and to evaluate the correlation of these variables with right heart catheterization-calculated pulmonary vascular resistance (PVR). SETTING Single university hospitals. PARTICIPANTS Patients undergoing elective PTE surgery between November 2016 and February 2018. METHODS All patients received a pulmonary artery catheter and arterial line, and transesophageal echocardiographic monitoring was performed. Transesophageal echocardiographic monitoring before surgery (pre-PTE) and postsurgery (post-PTE) included comprehensive 2D examinations and 3D right ventricular data set acquisition for offline volumetric analysis. Right ventricular fractional area of change (RVFAC) was measured from a right ventricular-focused midesophageal 4-chamber view. TomTec-Arena 4D RV-Function 2.0 offline software (TomTec Imaging Systems GmbH, Unterschlessheim, Germany) was used to measure right ventricular end diastolic volume (RVEDV), right ventricular end systolic volume (RVESV), and right ventricular ejection fraction (RVEF). Paired t tests were used to evaluate for differences before and after surgery, and echocardiographic variables versus PVR were analyzed with linear regression. RESULTS Forty patients were scheduled for elective PTE surgery; 35 patients had complete hemodynamic profiles and echocardiographic data sets and were included in the evaluation. Mean pulmonary artery pressure decreased from 40 ± 11 to 28 ± 7 mmHg, and PVR decreased from 708 ± 432 to 285 ± 136 dynes*s/cm5 after PTE. RVEDV decreased from 106 ± 43 to 79 ± 35 cm3 (p < 0.001), and RVESV decreased from 77 ± 36 to 59 ± 31 cm3 (p < 0.001). A statistically significant change was not identified in RVEF or RVFAC post-PTE compared with pre-PTE values. All volumetric analyses and RVFAC correlated poorly with PVR (pre-PTE RVEDV correlation to PVR [R2 = 0.004]; post-PTE RVEDV correlation to PVR [R2 = 0.024]). CONCLUSION Even though RVEDV and RVESV displayed a statistically significant change after PTE, this study did not identify a correlation between those variables and PVR. In addition, markers of right ventricular systolic function (eg, RVFAC and RVEF) did not correlate with PVR. Therefore, the authors conclude that even though these echocardiographic measurements quantified a statistically significant change after PVR reduction, they cannot be reliably used as a surrogate marker of success immediately after PTE.

Pulmonary Artery Catheter Placement Aided by Transesophageal Echocardiography versus Pressure Waveform Transduction

OBJECTIVE To compare pulmonary artery catheter (PAC) placement by transesophageal echocardiography combined with pressure waveform transduction versus the traditional technique of pressure waveform transduction alone. DESIGN A prospective, randomized trial. SETTING Single university hospital. PARTICIPANTS Forty-eight patients with chronic thromboembolic pulmonary hypertension (CTEPH) scheduled for pulmonary thromboendarterectomy. INTERVENTIONS PACs were placed in 48 patients with CTEPH scheduled for pulmonary thromboendarterectomy by either a combined approach (eg, transesophageal echocardiography [TEE] and pressure waveform transduction) or by pressure waveform transduction alone. MEASUREMENTS AND MAIN RESULTS Successful placement of the PAC via a combined technique or pressure waveform transduction alone was timed, number of attempts recorded, and final location noted. The final location of the pressure waveform-guided catheters was the proximal right pulmonary artery in 6 of 24 cases (25%), whereas the combined method resulted in successful placement in the proximal right pulmonary artery in 24 of 24 cases (100%). The pressure waveform technique resulted in a mean time to placement and mean number of attempts of 74 seconds and 1.70 attempts, respectively. The combined approach resulted in a mean time to placement and mean number of attempts of 89 seconds and 1.79 attempts, respectively. The combined method resulted in placement in the proximal right pulmonary artery significantly more often than the pressure-only method but did not reduce significantly the number of attempts or time required to place the catheter successfully. Additionally, among those cases that required more than 1 attempt or manipulation, there was no difference in the time to successful placement or the number of attempts required for successful placement. CONCLUSION TEE guidance during PAC insertion was hypothesized to result in a higher success rate, precise placement, and shorter times to placement. One hundred percent of the PACs inserted with TEE guidance were positioned successfully in the proximal right pulmonary artery, which is the institutional preference. Although the combined technique resulted in greater precision, the clinical significance of this is unknown. The time to placement benefit was not confirmed by this study.

Regional Ventricular Function

One of the most useful applications of intra-operative 2D transesophageal echocardiography (TEE) in noncardiac surgery is qualitative assessment of myocardial function in acutely unstable patients. When hemodynamic instability occurs intraoperatively, TEE can serve as an adjunct to other modalities in diagnosing or ruling out an ischemic event. In fact, compared to other monitoring methods, regional wall motion abnormality (RWMA) observed on echocardiography is the most sensitive method for early detection of ischemic changes in the heart. In noncardiac surgery, this can be especially useful in patients with no existing invasive or detailed monitoring that shows a sudden change in clinical status. Knowledge of normal coronary anatomy and its myocardial distribution is key in determining the location of an ischemic event. Recognizing the attributes of a wall motion abnormality such as decreased wall excursion or decreased wall thickening is key in diagnosing ischemic events, while recognizing that not all wall motion abnormalities are ischemic events (e.g., pacing effect).