Repeated Monitoring With Transthoracic Echocardiography and Lung Ultrasound After Cardiac Surgery: Feasibility and Impact on Diagnosis

https://doi.org/10.1053/j.jvca.2015.08.033Get rights and content

Objectives

Cardiorespiratory complications are common after cardiac surgery and current monitors used to diagnose these are invasive and have limitations. Transthoracic echocardiography and lung ultrasound are noninvasive and frequently improve diagnosis in critically ill patients but have not been reported for routine postoperative monitoring after coronary, valve, and aortic surgery. The aim was to determine whether both repeated postoperative transthoracic echocardiography and lung ultrasound revealed or excluded clinically important cardiac and respiratory disorders compared to conventional monitoring and chest x-ray.

Design

Prospective observational study.

Setting

Tertiary university hospital.

Participants

Ninety-one patients aged older than 18 undergoing cardiac surgery

Interventions

Postoperative clinical patient assessment for significant cardiac and respiratory disorders by the treating physician was recorded at 3 time points (day after surgery, after extubation and removal of chest drains and at discharge) using conventional monitoring and chest x-ray. After each assessment, transthoracic echocardiography and lung ultrasound were performed, and differences in diagnosis from conventional assessment were recorded.

Measurements and Main Results

Transthoracic echocardiography was interpretable in at least 1 echocardiographic window in 99% of examinations. Transthoracic echocardiography and/or lung ultrasound changed the diagnosis of important cardiac and/or respiratory disorders in 61 patients (67%). New cardiac findings included cardiac dysfunction (38 patients), pericardial effusion (5), mitral regurgitation (2), and hypovolemia (1). New respiratory findings included pleural effusion (30), pneumothorax (4), alveolar interstitial syndrome (3) and consolidation (1).

Conclusions

Routine repeated monitoring with cardiac and lung ultrasound after cardiac surgery is feasible and frequently alters diagnosis of clinically important cardiac and respiratory pathology.

Section snippets

Methods

This prospective observational study received ethics approval from the King Saud University Health System (Riyadh, Saudi Arabia) and the Melbourne Health Human Ethics Committee (Australia). Patients presenting for cardiac surgery between July 2011 and August 2012 at The King Fahad Cardiac Center of King Saud University were screened for inclusion (convenience sampling) by research personnel. Inclusion criteria included patients older than 18 and informed consent from the patient or legal

Statistical Analysis

The sample size calculation was based on reported data from TTE performed on emergency noncardiac surgery patients,21 in which assessment for concordance between clinical and ultrasound assessment of the hemodynamic state was 50%. A sample size of 77 pairs will have 80% power to detect a difference in proportions of 10% when the proportion of discordant pairs is expected to be 12% using McNemar’s test, with a significance of p<0.05. To account for patient exclusions and an expected 12% rate of

Results

Of the 275 patients who underwent cardiac surgery over the study period, 91 were recruited when researchers were available for recruitment and data were complete in all patients. Patient characteristics are shown in Table 2. Comparison of the diagnosis of cardiac and respiratory abnormalities between clinical assessment and ultrasound over the 3 time points (T1-the day after surgery, T2-after extubation and removal of drains, and T3-prior to discharge) are shown in Table 3, Table 4, Table 5.

Discussion

This study demonstrated proof of concept that TTE and LU result in a change in diagnosis in a high proportion of patients when performed after cardiac surgery at repeated intervals, providing utility as routine monitors for complications, rather than to provide diagnosis for persistent shock, as previously has been reported. It also was shown that LU provided additional diagnostic value to TTE, which can be performed conveniently at the same time.

Feasibility of TTE performed on patients after

Acknowledgments

This project was supported by National Science, Technology and Innovation. Plan, King Abdulaziz City for Science and Technology, Kingdom of Saudi Arabia (Grant number 11-MED 1932-02). The funding body had no involvement in study design; in the collection, analysis and interpretation of data; in the writing of the report; and in the decision to submit the article for publication. The authors are grateful for Drs. Fakhr Al Ayoubi, KN Asfena and Mr. Nabeel Rabea, RN who managed, recorded the data,

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