By Davinder S. Ramsingh, MD
Anesthesiologists have been leaders in the use of point-of-care (POC) ultrasound for intraoperative transesophageal echocardiography (TEE), and to guide vascular access and regional anesthesia procedures. Recently, anesthesiologists have taken a leadership role in implementing the Perioperative Surgical Home (PSH) model, created by the American Society of Anesthesiologists to provide a team-based system of coordinated care that guides the patient throughout the entire surgical experience. POC ultrasound is a versatile technology with a wide range of evidence-based applications to help anesthesiologists achieve the goals of the PSH model, which aims to use proven best practices to improve the safety and quality of care, outcomes and patient satisfaction, while reducing costs, length of stay (LOS), complications and readmissions.
Recently, the author and colleagues have assessed the integration of an evidence-based, whole-body POC ultrasound curriculum (Focused periOperative Risk Evaluation Sonography Involving Gastroabdominal Hemodynamic and Transthoracic ultrasound [FORESIGHT]) into residency training for anesthesiologists (Ramsingh, Rinehart, Kain et al, 2015). Our team found that POC ultrasound assessments after the study affected clinical management in 76% of cases and detected new pathology in 31%, suggesting that FORESIGHT training and assessments may provide significant clinical benefit in the PSH model. This curriculum has been implemented at several major academic centers. Recently, the Department of Anesthesiology at Loma Linda University Medical Center has launched the curriculum as a free-to-access, copyright-free, online platform at www.foresightultrasound.com.
This review offers an overview of 10 clinically valuable applications of POC ultrasound for anesthesiologists, including the major components of the FORESIGHT ultrasound examination: (1) cardiac, (2) pulmonary, (3) hemodynamics, (4) abdominal, (5) airway, (6) advanced vascular access and (7) intracranial. Ultrasound-guided regional anesthesia (UGRA), which is now included in many Enhanced Recovery After Surgery (ERAS) protocols, and perioperative use of the FAST (Focused Assessment with Sonography for Trauma) examination are also discussed.
- Cardiac ultrasound. Focused cardiac ultrasound performed by anesthesiologists is an extremely valuable tool. This application of POC ultrasound has been shown to accurately detect major cardiac pathology and significantly alter perioperative management in 82% of cases (Cowie, 2011). Moreover, transthoracic examination of the cardiopulmonary system using POC ultrasound has proven to be a reliable tool when compared with formal echocardiography (Andersen, Haugen et al, 2011) and can be taught to noncardiologists (Manasia, Nagaraj et al, 2005). POC cardiac assessments include right and left ventricular function and identification of pericardial effusion and severe valvular abnormalities. Guidelines have been published for POC cardiac ultrasound by critical care physicians (Mazraeshahi, Farmer et al, 2007). Given the similarity between the intensive care unit and the operating room, the FORESIGHT curriculum includes similar guidelines.
- Pulmonary If a patient develops shortness of breath or cannot get enough oxygen in the bloodstream, thoracic ultrasound can diagnose an effusion, collapsed lung or pulmonary edema much faster than the time that would be required to obtain a chest x-ray, thus accelerating potentially lifesaving care. In the critical care setting, ultrasonography has a diagnostic accuracy of 93% for the detection of pleural effusion, 97% for alveolar consolidation and 95% for alveolar-interstitial syndrome, versus accuracy of 47%, 75% and 72% respectively for bedside chest radiography (Lichtenstein, Goldstein et al, 2004). Ultrasound also has proven valuable for the detection of pneumothorax (Ueda, Ahmed & Ross, 2011).
- Regional anesthesia. Increasingly, Enhanced Recovery After Surgery (ERAS) protocols include regional anesthesia techniques, which reduce surgically induced stress, inflammation and complications, improve postoperative pain control and expedite recovery, including early ambulation (Eroglu, Erturk et al, 2017). This evidence-based approach to standardizing care of the surgical patient has been shown to improve outcomes, reduce length of stay by 30% to 50% and decrease complications (Eroglu, Erturk et al, 2017), leading to reported cost savings of up $7,129 per patient (Thiele, Rea et al, 2015). A large body of evidence has shown that UGRA results in longer block durations, faster onset times, improved block success and a reduced need for opioids (Lewis, Price, 2015) (Munirama, McLeod, 2015).
- Transesophageal echocardiography (TEE). TEE, performed by anesthesiologists, is a critically important imaging modality in the cardiac operating room, providing important input for surgical decision-making to optimize intraoperative care. Guidelines from the American Society of Echocardiography and the Society of Cardiovascular Anesthesiologists recommend the use of TEE on all open heart and thoracic aortic surgical procedures, some coronary artery bypass graft procedures and noncardiac surgery in patients with known or suspected cardiovascular pathology. The guidelines also report that by providing “an excellent ultrasonic window” into much of the heart and great vessels, TEE provides “additional and more accurate information than transthoracic echocardiography (TTE) for some patients, several specific diagnoses and for many catheter-based cardiac interventions.”
- Hemodynamics. POC ultrasound offers several modalities to enable the evaluation of the ventricular filling pressures and fluid responsiveness, which are frequent concerns in the perioperative setting. For example, assessments of the collapsibility of the inferior vena cana (Barbier, Loubières, 2004) and left ventricular (LV) end-diastolic area provide accurate measurements of reduced filling pressure (Scheuren, Wente et al, 2009). Ultrasound can also be used to evaluate respiratory variation on Doppler Flow across left ventricular outflow tract) LVOT (Miller & Mandeville, 2006) or peripheral arteries (Monge, Cana & Diaz, 2009).
- Airway ultrasound. Unrecognized malposition of the endotracheal tube (ETT) can lead to severe or fatal complications in patients undergoing general anesthesia. In a recent double-blind study of adult surgical patients, our team demonstrated that POC ultrasound was superior to auscultation for verifying proper placement of the ETT, with a sensitivity of 93% and a specificity of 96% in the ultrasound group, versus 66% and 59% respectively for the auscultation group (Ramsingh, Haughton et al, 2016). Patients were randomly assigned to right main brochus, left main bronchus or tracheal intubation. Successful use of POC ultrasound for adjunct confirmation of tracheal versus esophageal intubation has also been described (Muslu, Sert et al, 2011).
- Vascular access. In 2001, the Agency for Healthcare & Quality Research identified ultrasound-guided central venous catheterization (CVC) placement as one of the top 12 practices to improve patient safety (AHRQ, 2001). Endorsed in guidelines from numerous medical societies, ultrasound-guided CVC is now the standard of care (Moore, 2014). Rates as low as zero for CVC complications, including pneumothorax and hemothorax (Fragou, Gravvanis et al, 2011), have been reported with ultrasound guidance, which has also been shown to reduce central-line-associated bloodstream infections by 35% (O’Grady, Alexander et al , 2002). In a 2016 policy statement, the American College of Emergency Physicians (ACEP) recommended use of POCUS for CVC and peripheral line placements to improve safety, reduce procedural complications, and “enable a one-stick standard” for vascular access (ACEP, 2016).
- Gastric ultrasound. Gastric ultrasound (GUS) is an emerging diagnostic application of POCUS, performed by anesthesiologists to assess how full the patient’s stomach may be, instead of relying on patients to inform us when they last ate. The goal is to prevent pulmonary aspiration of vomitus. Recently a grading system based on the qualitative sonographic evaluation of the gastric antrum has demonstrated a strong correlation with gastric volume (Perlis, Mitsakakis et al, 2013) . Mounting evidence suggests that GUS can change aspiration risk stratification, improving patient safety and outcomes (Perlas, Van de Putte et al, 2016). Moreover, GUS is easy for anesthesiologists to learn and its findings have been shown to be accurate and reliable (Arzola, Carvalho et al, 2013).
- Focused Assessment with Sonography for Trauma (FAST). The FAST examination is well established as the imaging modality of choice to assess trauma patients for potentially life-threatening injuries by detecting free fluid in the peritoneal, pleural or pericardial space (typically a sign of hemorrhage in trauma patients). The FAST examination has an overall accuracy of up to 98% for detecting clinically significant intra-abdominal injury in trauma patients (Moore & Copel, 2011). In the perioperative setting, this examination can also be used to assess hypotensive patients for immediate evidence of surgical bleeding after an abdominal or pelvic procedure. Use of the FAST examination to detect intra-abdominal fluid extravasation in patients who have undergone hip arthroscopy has recently been described (Haskins, Desai, 2017).
- Intracranial pressure (ICP) assessment. POC ultrasound provides rapid assessment of elevated ICP though measurements of optic nerve sheath diameter (ONSD) (Dubost, Gouez et al, 2012). Numerous studies and a recent meta-analysis have confirmed the accuracy of ONSD as a noninvasive surrogate marker of raised ICP (Dubourg, Javouhey, 2011). Because of the potential adverse impact of elevated ICP on patients’ outcomes, this assessment can play a valuable role in the perioperative setting.
In the era of value-based care, a rapidly growing body of evidence has shown that POC ultrasound in the perioperative setting is not just convenient and safe, but also can significantly change management and improve clinical outcomes. In a study at Loma Linda University Departments of Anesthesiology and Urology, our team implemented a perioperative hospitalist service (PHS) consisting of anesthesiology-trained physicians to co-manage patients undergoing major urological surgery throughout their perioperative stay. We demonstrated significant reductions in LOS, complications and direct costs, as compared with pre-PHS care. Our findings suggest that anesthesiologists can diversify their practice paradigms, significantly improve both patient recovery and throughput, and decrease costs by up to 22% (Stier, Ramsingh et al, 2018).
Anesthesiologists have a long history of using technology, including pulse oximetry, capnography and cardiac output devices, to advance patient safety and the quality of care. Our specialty was also an early adopter of POC ultrasound in the intraoperative setting, but has lagged behind some of the other specialties in incorporating all of its utility and embracing all of the relevant applications. With the advent of the PSH model and the expanded role it provides for anesthesiologists, it is time for us to become the leaders in using ultrasound visualization and the crucial insights it provides to take comprehensive perioperative care to the next level of excellence.
– Davinder S. Ramsingth, MD, is Director of Research and Perioperative Ultrasound at Loma Linda University Medical Center, Department of Anesthesiology. Dr. Ramsingh is also Associate Professor, Anesthesiology at Loma Linda University School of Medicine. He previously served as Director of Cardiac Anesthesiology and Director of Perioperative Ultrasound at University of California at Irvine (UCI). While at UCI, Dr. Ramsingh developed an innovative teaching program for anesthesiologists to apply a whole-body point-of-care ultrasound examination. He has directed national sessions and has published several articles on perioperative point-of-care ultrasound. His research interests also include hemodynamic monitoring. He has developed and implemented protocols for hemodynamic monitoring in a variety of patient care settings at several large medical centers.