Potential for Orogastric Tube Attached Transesophageal Echocardiography to Improve Intraoperative Image Quality

Transesophageal echocardiography (TEE) has been used clinically for decades1Matsumoto M. Oka Y. Strom J. et al.Application of transesophageal echocardiography to continuous intraoperative monitoring of left ventricular performance.Am J Cardiol. 1980; 46: 95-105Abstract Full Text PDF PubMed Scopus (159) Google Scholar and is now a standard intraoperative diagnostic technique for cardiac and noncardiac surgeries.2Reeves S.T. Finley A.C. Skubas N.J. et al.Council on Perioperative Echocardiography of the American Society of Echocardiography and the Society of Cardiovascular Anesthesiologists. Special article: Basic perioperative transesophageal echocardiography examination: A consensus statement of the American Society of Echocardiography and the Society of Cardiovascular Anesthesiologists.Anesth Analg. 2013; 117: 543-558Crossref PubMed Scopus (59) Google Scholar, 3Thys D.M. Brooker R.F. Cahalan M.K. et al.Practice guidelines for perioperative transesophageal echocardiography. An updated report by the American Society of Anesthesiologists and the Society of Cardiovascular Anesthesiologists Task Force on Transesophageal Echocardiography.Anesthesiology. 2010; 112: 1084-1096Crossref PubMed Scopus (388) Google Scholar, 4Hahn R.T. Abraham T. Adams M.S. et al.Guidelines for performing a comprehensive transesophageal echocardiographic examination: Recommendations from the American Society of Echocardiography and the Society of Cardiovascular Anesthesiologists.J Am Soc Echocardiogr. 2013; 26: 921-964Abstract Full Text Full Text PDF PubMed Scopus (711) Google Scholar, 5Porter T.R. Shillcutt S.K. Adams M.S. et al.Guidelines for the use of echocardiography as a monitor for therapeutic intervention in adults: A report from the American Society of Echocardiography.J Am Soc Echocardiogr. 2015; 28: 40Abstract Full Text Full Text PDF PubMed Scopus (255) Google Scholar, 6Suriani R.J. Cutrone A. Feierman D. et al.Intraoperative transesophageal echocardiography during liver transplantation.J Cardiothorac Vasc Anesth. 1996; 10: 699-707Abstract Full Text PDF PubMed Scopus (86) Google Scholar As TEE plays a major role in quantitative and qualitative evaluations of the heart, accurate assessment is critical.7Picard M.H. Adams D. Bierig S.M. et al.American Society of Echocardiography recommendations for quality echocardiography laboratory operations.J Am Soc Echocardiogr. 2011; 24: 1-10Abstract Full Text Full Text PDF PubMed Scopus (272) Google Scholar, 8Yu C.M. Challenges and opportunity in the era of quantitative echocardiography.Echo Res Pract. 2017; 4: E3-E6Crossref PubMed Scopus (2) Google Scholar Despite remarkable progress in spatial resolution and postprocessing,9Menchón-Lara R.M. Bastida-Jumilla M.C. Morales-Sánchez J. et al.Automatic detection of the intima-media thickness in ultrasound images of the common carotid artery using neural networks.Med Biol Eng Comput. 2014; 52: 169-181Crossref PubMed Scopus (46) Google Scholar, 10Providian Medical Equipment. Ultrasound imaging guide: A quick and easy guide for optimizing ultrasound images. Available at: https://www.providianmedical.com/ultrasound-imaging-guide/. Accessed January 26, 2018.Google Scholar, 11Kaplan J.A. Augoustides J.G.T. Manecke G.R. Maus T.M. Reich D.L. Kaplan’s cardiac anesthesia e-book: in cardiac and noncardiac surgery. 7th ed. Elsevier, Philadelphia, PA2016Google Scholar, 12Mathew J.P. Swaminathan M. Ayoub C.H. Clinical manual and review of transesophageal echocardiography. 2nd ed. McGraw-Hill Education, New York, NY2010Google Scholar, 13Perrion Jr., A.C. Reeves S.T. A practical approach to transesophageal echocardiography. 3rd ed. Lippincott Williams & Wilkins, Philadelphia, PA2014Google Scholar, 14Thiele K, Jago J, Entrekin R, Peterson R. Exploring nSIGHT Imaging – a totally new architecture for premium ultrasound: Philips EPIQ ultrasound system. Available at: http://incenter.medical.philips.com/doclib/enc/fetch/2000/4504/577242/577260/593280/593431/nSIGHT_Imaging.pdf%3fnodeid%3d9910980%26vernum%3d1?elqaid=131&elqat=2&elqTrackId=3459eb6311294d20a874471903231dc7.Google Scholar image quality for TEE requires improvement for assistance with transmitting ultrasound.15Bainbridge D. Martin J. Ahmad Sabry M.H. Craig A. Iglesias I. Orogastric tubes do not improve transesophageal echocardiographic imaging during cardiac surgery: A randomized trial.Can J Anaesth. 2010; 57: 216-221Crossref PubMed Scopus (8) Google Scholar, 16Zagzebski J.A. Essentials of ultrasound physics. Mosby, St. Louis, MO1996Google Scholar, 17Goldstein A. Powis R.L. Medical ultrasonic diagnostics.Physical Acoustics. 1999; 23: 43-191Crossref Scopus (13) Google Scholar We devised an orogastric tube attached TEE probe (OGT-TEE probe) (Fig 1) to allow pinpoint suction and prevent stomach distension during the TEE examination. We hypothesized that pinpoint suction using an OGT-TEE probe would improve TEE image quality. This single-center study used a 2-point evaluation process to assess TEE image quality with the OGT-TEE probe. Preoperatively, we attached a 16 French OG tube (Covidien LLC, Mansfield, MA) to an X7 TEE probe (Philips Medical Systems, Andover, MA) using a silk surgical suture. After institutional review board approval, patients were selected for OGT-TEE assessment based on intraoperative TEE indications for open heart surgeries and orthotopic liver transplantation (OLT) as previously described.2Reeves S.T. Finley A.C. Skubas N.J. et al.Council on Perioperative Echocardiography of the American Society of Echocardiography and the Society of Cardiovascular Anesthesiologists. Special article: Basic perioperative transesophageal echocardiography examination: A consensus statement of the American Society of Echocardiography and the Society of Cardiovascular Anesthesiologists.Anesth Analg. 2013; 117: 543-558Crossref PubMed Scopus (59) Google Scholar, 3Thys D.M. Brooker R.F. Cahalan M.K. et al.Practice guidelines for perioperative transesophageal echocardiography. An updated report by the American Society of Anesthesiologists and the Society of Cardiovascular Anesthesiologists Task Force on Transesophageal Echocardiography.Anesthesiology. 2010; 112: 1084-1096Crossref PubMed Scopus (388) Google Scholar, 4Hahn R.T. Abraham T. Adams M.S. et al.Guidelines for performing a comprehensive transesophageal echocardiographic examination: Recommendations from the American Society of Echocardiography and the Society of Cardiovascular Anesthesiologists.J Am Soc Echocardiogr. 2013; 26: 921-964Abstract Full Text Full Text PDF PubMed Scopus (711) Google Scholar, 5Porter T.R. Shillcutt S.K. Adams M.S. et al.Guidelines for the use of echocardiography as a monitor for therapeutic intervention in adults: A report from the American Society of Echocardiography.J Am Soc Echocardiogr. 2015; 28: 40Abstract Full Text Full Text PDF PubMed Scopus (255) Google Scholar, 6Suriani R.J. Cutrone A. Feierman D. et al.Intraoperative transesophageal echocardiography during liver transplantation.J Cardiothorac Vasc Anesth. 1996; 10: 699-707Abstract Full Text PDF PubMed Scopus (86) Google Scholar All patients gave written consent to participate in this study. All patients received general anesthesia with endotracheal intubation, standard American Society of Anesthesiologists monitoring, arterial blood pressure monitoring, central venous pressure monitoring, pulmonary artery pressure monitoring, and TEE. Patient demographics and characteristics were collected from our computerized patient database. TEE images were collected using an iE33 echocardiographic machine (Philips Medical Systems). After induction of general anesthesia, a regular OG tube was placed and removed after suctioning the stomach. The OGT-TEE probe then was inserted. Transgastric left ventricle short-axis (TG LV SAX) views and midesophageal 4-chamber views (ME 4CV) were captured for 5 consecutive beats before and after suctioning using the OGT-TEE probe. For open heart surgeries, suction occurred when weaning the patient from cardiopulmonary bypass was completed. For OLT cases, suction occurred after reperfusion or when surgeons complained about distended stomach. Suction was performed for 1 minute at >–110 cm H2O, and amount and characteristics of suction content were recorded. While acquiring these views, the TEE device setting remained unchanged and the iSCAN button was used before movie acquisition.18https://www.usa.philips.com/healthcare/product/HC795113/diamond-select-ie33-refurbished-ultrasound-machineGoogle Scholar TG LV SAX view and ME 4CV of 47 cases (cardiac surgeries: 24 cases, OLT: 23 cases) were used for postoperative measurements. Three echocardiography board–certified researchers (researcher A, B, and C), who were blinded to study design, were assigned to each case, and they assessed the same images independently. Images with significant wall motion abnormality were excluded from assessment. Image quality assessment was performed using 2 methods. First, these 3 researchers rated image quality using a 5-point Likert scale (1: very bad, 2: bad, 3: acceptable, 4: good, and 5: very good) before and after suctioning. Second, these 3 researchers measured LV fractional area change (FAC) and right ventricle (RV) FAC for all images. Researcher C, who was picked randomly among 3 researchers, was asked to evaluate LV FAC and RV FAC again using the same images after a 6- to 8-month interval. For this second method, intraobserver and interobserver reliability analyses of LV FAC and RV FAC were performed using intraclass correlation coefficient (ICC).19Koo T.K. Li M.Y. A guideline of selecting and reporting intraclass correlation coefficients for reliability research.J Chiropr Med. 2016; 15: 155-163Crossref PubMed Scopus (9870) Google Scholar, 20Shrout P.E. Fleiss J.L. Intraclass correlations: Uses in assessing rater reliability.Psychol Bull. 1979; 86: 420-428Crossref PubMed Scopus (17144) Google Scholar, 21McGraw K.O. Wong S.P. Forming inferences about some intraclass correlation coefficients.Psychol Methods. 1996; 1: 30-46Crossref Scopus (4642) Google Scholar We obtained consistency ICC for interobserver variability using assessments by all 3 researchers, and absolute-agreement ICC for intraobserver variability using 2 assessments done 6 to 8 months apart by researcher C. Our study meets the criteria for conducting a reliable study using ICC, which needs at least 30 heterogeneous samples and 3 raters.19Koo T.K. Li M.Y. A guideline of selecting and reporting intraclass correlation coefficients for reliability research.J Chiropr Med. 2016; 15: 155-163Crossref PubMed Scopus (9870) Google Scholar All statistical analyses were performed with R (version 3.4.3). Fifty-three patients (29 open heart surgeries and 24 OLTs) were enrolled in this study. The TEE study was aborted in 3 patients due to resistance on OG tube insertion. The other 3 patients were excluded due to significant wall motion abnormality. Thus 47 cases (24 open heart surgeries and 23 OLTs) were included for image analysis by the 3 investigators. None of the patients had clinically significant TEE-related complications, such as persistent sore throat, dysphagia/odynophagia, vocal cord palsy, significant gastrointestinal bleeding, significant oral bleeding, or teeth damage.22Hilberath J.N. Oakes D.A. Shernan S.K. et al.Safety of transesophageal echocardiography.J Am Soc Echocardiogr. 2010; 23: 1115-1127Abstract Full Text Full Text PDF PubMed Scopus (340) Google Scholar For the TG LV SAX views before and after suction, among 47 × 3 sets of images, 79 images (56.0%) showed improved quality and 62 images (44.0%) showed the same quality by Likert score. Pre-suction LV FAC of 2 cases was not measurable due to significantly poor image quality, which improved enough for measurement after OGT-TEE suction. The ICCs for the inter- and intraobserver analyses of LV FAC before and after suction are provided in Table 1.Table 1(ICC of LV FAC Before and After SuctionGroupICC95% CIInter-observerPre-suction0.659(0.511-0.78)Post-suction0.903(0.849-0.941)Intra-observerPre-suction0.716(0.536-0.833)Post-suction0.935(0.887- 0.963)Note that relationship between the reliability and the ICC values is as below7Picard M.H. Adams D. Bierig S.M. et al.American Society of Echocardiography recommendations for quality echocardiography laboratory operations.J Am Soc Echocardiogr. 2011; 24: 1-10Abstract Full Text Full Text PDF PubMed Scopus (272) Google Scholar;ICCReliability>0.90Excellent0.75-0.90Good0.50-0.75Moderate<0.50PoorNOTE: The 95% CI of ICC for post-suction does not overlap with pre-suction, indicating the significant improvement of image quality after suction.Abbreviations: CI, confidence interval; ICC, intraclass correlation coefficient; LV FAC, left ventricular fraction area change. Open table in a new tab NOTE: The 95% CI of ICC for post-suction does not overlap with pre-suction, indicating the significant improvement of image quality after suction. Abbreviations: CI, confidence interval; ICC, intraclass correlation coefficient; LV FAC, left ventricular fraction area change. For ME 4CV views before and after suction, among 47 × 3 sets of images, 30 images (21.3%) showed improved quality, 12 images (8.5%) showed worsened quality, and 99 images (70.2%) showed the same quality by Likert scoring. RV FAC was measurable for all the images. The ICCs for the inter- and intraobserver analyses of RV FAC before and after suction are provided in Table 2.Table 2ICC of RV FAC Before and After SuctionGroupICC95% CIInter-observerPre-suction0.874(0.806, 0.923)Post-suction0.871(0.802, 0.921)Intra-observerPre-suction0.840(0.674, 0.917)Post-suction0.913(0.849, 0.951)NOTE. The 95% CI of ICC for post suction overlaps with pre-suction, indicating no significant improvement of image quality after suction.Abbreviations: CI, confidence interval; ICC, intraclass correlation coefficient; RV FAC, right ventricular fraction area change. Open table in a new tab NOTE. The 95% CI of ICC for post suction overlaps with pre-suction, indicating no significant improvement of image quality after suction. Abbreviations: CI, confidence interval; ICC, intraclass correlation coefficient; RV FAC, right ventricular fraction area change. None of the patients experienced dislodged OG tube after TEE probe removal. For OLTs, 15 of 24 patients (62.5%) were noticed to have abdominal distension by surgeons intraoperatively, and the stomach was witnessed to shrink after suction in all 15 cases. We chose RV FAC and LV FAC to compare the effect of suction on midesophageal and transgastric views. Our results show that the transgastric view was significantly better with suction, while the midesophageal view was not. In the transgastric view, the OGT-TEE probe is in the stomach and suction works to shrink the stomach when distended, thus reducing media between the TEE transducer and the heart. In the midesophageal view, the OGT-TEE probe is in the esophagus and suction does not change the distance much between the TEE transducer and the heart. Modern echocardiographic machines have an automatic adjustment system to optimize spatial resolution and postprocessing by time gain compensation, receiver gain, and system compression map.8Yu C.M. Challenges and opportunity in the era of quantitative echocardiography.Echo Res Pract. 2017; 4: E3-E6Crossref PubMed Scopus (2) Google Scholar, 9Menchón-Lara R.M. Bastida-Jumilla M.C. Morales-Sánchez J. et al.Automatic detection of the intima-media thickness in ultrasound images of the common carotid artery using neural networks.Med Biol Eng Comput. 2014; 52: 169-181Crossref PubMed Scopus (46) Google Scholar, 10Providian Medical Equipment. Ultrasound imaging guide: A quick and easy guide for optimizing ultrasound images. Available at: https://www.providianmedical.com/ultrasound-imaging-guide/. Accessed January 26, 2018.Google Scholar, 11Kaplan J.A. Augoustides J.G.T. Manecke G.R. Maus T.M. Reich D.L. Kaplan’s cardiac anesthesia e-book: in cardiac and noncardiac surgery. 7th ed. Elsevier, Philadelphia, PA2016Google Scholar, 14Thiele K, Jago J, Entrekin R, Peterson R. Exploring nSIGHT Imaging – a totally new architecture for premium ultrasound: Philips EPIQ ultrasound system. Available at: http://incenter.medical.philips.com/doclib/enc/fetch/2000/4504/577242/577260/593280/593431/nSIGHT_Imaging.pdf%3fnodeid%3d9910980%26vernum%3d1?elqaid=131&elqat=2&elqTrackId=3459eb6311294d20a874471903231dc7.Google Scholar, 15Bainbridge D. Martin J. Ahmad Sabry M.H. Craig A. Iglesias I. Orogastric tubes do not improve transesophageal echocardiographic imaging during cardiac surgery: A randomized trial.Can J Anaesth. 2010; 57: 216-221Crossref PubMed Scopus (8) Google Scholar However, even with these technologies, intermediating gas between the ultrasound transducer and object will affect image quality significantly because of ultrasound velocity difference in different media.11Kaplan J.A. Augoustides J.G.T. Manecke G.R. Maus T.M. Reich D.L. Kaplan’s cardiac anesthesia e-book: in cardiac and noncardiac surgery. 7th ed. Elsevier, Philadelphia, PA2016Google Scholar, 12Mathew J.P. Swaminathan M. Ayoub C.H. Clinical manual and review of transesophageal echocardiography. 2nd ed. McGraw-Hill Education, New York, NY2010Google Scholar, 13Perrion Jr., A.C. Reeves S.T. A practical approach to transesophageal echocardiography. 3rd ed. Lippincott Williams & Wilkins, Philadelphia, PA2014Google Scholar, 16Zagzebski J.A. Essentials of ultrasound physics. Mosby, St. Louis, MO1996Google Scholar, 17Goldstein A. Powis R.L. Medical ultrasonic diagnostics.Physical Acoustics. 1999; 23: 43-191Crossref Scopus (13) Google Scholar In our study, we were not able to measure the amount of air suctioned because the upper gastrointestinal tract is an open system and thus the suctioned amount of air likely would not be related to post-suction stomach size reduction. Instead, we used enough negative pressure and time for suctioning the stomach. The benefit of our OGT-TEE probe for shrinking stomach size intraoperatively was witnessed visually by the surgeons in the OLT cases. These findings would support our hypothesis that air existing between the TEE transducer and stomach wall is one of the critical factors that affect TEE image quality, and sucking air with pinpoint suction would be feasible for improving image quality. Our pinpoint suction strategy has additional potential benefits. With achieving better image quality, the echocardiographer would be able to avoid too much probe manipulation, which would lead to less trauma to surrounding tissue. Trauma to surrounding tissue with the TEE probe has been reported to be rarely critical.22Hilberath J.N. Oakes D.A. Shernan S.K. et al.Safety of transesophageal echocardiography.J Am Soc Echocardiogr. 2010; 23: 1115-1127Abstract Full Text Full Text PDF PubMed Scopus (340) Google Scholar However, this can be concerning in cardiac cases in which full heparinization is necessary, in aortic stenosis patients who have acquired von Willebrand disease and angiodysplasia,23Loscalzo J. From clinical observation to mechanism—Heyde’s syndrome.N Engl J Med. 2013; 368: 579-580Crossref PubMed Scopus (2) Google Scholar and in end-stage liver disease patients who commonly have esophageal or gastric varices as well as coagulopathy.24Forkin K.T. Colquhoun D.A. Nemergut E.C. et al.The coagulation profile of end-stage liver disease and considerations for intraoperative management.Anesth Analg. 2018; 126: 46-61Crossref PubMed Scopus (49) Google Scholar Especially for aortic valvulopathy patients or aortic valve procedures, transgastric or deep transgastric TEE views are useful for assessment of aortic valve pressure gradient and valve integrity, and it is important to minimize unnecessary manipulations of the TEE probe. Our investigation had several limitations. This study was limited by its single-center dataset. Image quality assessment can be subjective, although we incorporated intra- and interobserver variance for specific measurements of RV FAC and LV FAC in addition to categorizing image quality by Likert scale. Also, our investigation did not include the assessment of how improvement in image quality would benefit patient care, including surgical decision-making. These need to be investigated in further studies. Our OGT-TEE probe has a small but not zero risk of causing device-related complications, although they were not experienced in this clinical trial. In conclusion, our investigation validated potential image quality improvement using our devised OGT-TEE probe, which enables pinpoint suctioning at the TEE probe transducer. This image quality improvement might be beneficial for patient safety due to avoiding unnecessary TEE probe manipulation, but its clinical validity needs to be confirmed by further studies.