The Utility of an Interventional Radiology Trainee as a Member of the Intensive Care Unit Team N Dullet1, S Mathevosian2, R Ahuja3, A Anavim3, D Nguyen3, K Kansagra4, M Ferra3 1The University of Arizona, Tucson, AZ, 2UCLA David Geffen School of Medicine, Los Angeles, CA, 3Albert Einstein Medical Center, Philadelphia, PA, 4Kaiser Permanente Medical Center, Los Angeles, CA

Background Mechanical Ventilation and Non-Invasive Ventilation Rounding in the ICU POCUS Definitions The role of the IR resident varies by institution and type of ICU, with some The IR resident is uniquely positioned Knowledge of critical care principles is essential as the IR Vt (Tidal Volume) The volume delivered per respiratory cycle. 6-8mL/kg for ARDS, while 8-10mL/kg may be used for other patients to provide assistance with timely service has become involved in increasingly complex residents rotating in SICU and others rotating in a MICU. In some instances, the resident acts as a senior, while the resident may act as an intern in other diagnosis and procedures with patient care. An ICU rotation is now a requirement of the PEEP (Peak End Expiratory Pressure) The pressure applied at the end of the expiratory phase, which keeps the alveoli open cases. POCUS. POCUS applications will be integrated IR residency and ESIR pathway. The ICU RR (Respiratory Rate) Number of respirations, reported per minute more thoroughly discussed in an F O Percent oxygenation of inspired air, room air is 21% rotation is an opportunity for the IR trainee to learn I 2 During pre-charting and pre-rounding, it is essential to review the accompanying poster. critical ICU management principles. I:E ratio (Inspiratory to Expiratory Ratio) Length of inspiration relative to expiration, usually 1:2, can drips/vasopressors the patient is on, ventilatory status (SBT if patient is on POCUS diagnostic applications be increased in COPD vent), sedation, feeds/diet, mobility/PT/OT, delirium, lines/foley (and whether include: The Society of Interventional Radiology (SIR) Resident Ve (Minute Ventillation) Volume of gas exchanged per minute, calculated as RR x Vt they are needed), and daily labs. Radiology residents can use POCUS to • RUSH exam

Fellow Student (RFS) website has developed a critical PIP (Peak Inspiratory Pressure) Highest amount of pressure applied to the lungs during evaluate cardiac function, volume status, infections/pain, and more (reviewed • FAST exam care curriculum for IR trainees, within the Patient Care inspiration. Increases with elevated airway resistance in the next column) • Assessment of volume status Resources subsection. The curriculum is organized by • NSTI/Abscesses/soft tissue topics, such as shock, mechanical ventilation, cardiac Rounding in the ICU is a collaborative effort between infections Common Ventilator/NIMV Modes • Pneumonia emergencies, and fluids/electrolytes. residents/fellows/attendings, nursing staff, respiratory therapists, pharmacists, Mode and PT/OT. During rounds, orders, labs, imaging etc. are all discussed in a • DVT assessment AC (Assist Control) Currently the most common ventilator setting. Each breath is either patient initiated, or at a set collaborative manner. The radiology resident can assist with image POCUS assisted procedures include: The IR resident can serve several roles as a member of the backup rate), up to a certain volume or pressure. interpretation during rounds and provide input in additional imaging that may • Chest tube placement ICU team, primarily with image analysis, POCUS, and AC Pressure: ventilator delivers breath until set be needed. • Central venous access procedures. pressure is reached. Limits peak inspiratory • Lumbar punctures pressure.

AC Volume: patient receives a set Vt, without a Following rounding, the IR resident can help with POCUS guided procedures • Arterial line placement Arterial Blood Gas (ABG) limit on peak inspiratory pressure. and diagnosis, continued image analysis, and help other members of the team • Joint injections with image interpretation and ordering • Foreign body removal SIMV (Synchronous Intermittent Mandatory The ventilator allows spontaneous breaths in Diagnostic tool to evaluate the partial pressures of gas in Ventillation) between a set ventilation cycle. Increased work of the blood and the acid-base content. The ABG can provide breathing relative to AC modes Lessons from the ICU insight into respiratory status, metabolic status and BiPAP Means of providing ventilatory support without an disturbances, and treatment response. invasive artificial airway (endotracheal or tracheostomy tube). Provides supplemental The IR resident should go into the critical care/ICU rotation with the Definition, (normal range) Simplified Interpretation inspiratory tidal volume (versus CPAP, which does following educational goals in mind: Measured acid-base balance of the blood Below 7.35: acidemia not increase Vt or VE). When inspiration is (7.35-7.45) Above 7.45: alkalemia detected, inspiratory pressure (IPAP) is provided. • Ventilator management/NIMV, and when to use each one Measured partial pressure of CO2 in the Determines whether acidosis/alkalemia is When breath is at the end, and expiration is • Vasopressors, vasopressor titration, and use blood (35-45mmHg) due to a respiratory etiology. started, expiratory pressure (EPAP) is provided • Shock (cardiogenic, hemorrhagic, septic, obstructive) – pathophysiology PaCO2>40 with pH<7.4 = respiratory acidosis and management • Noninvasive ventilation decreases respiratory work: positive pressure PaCO2<40 with pH>7.4 = respiratory • Anticoagulation – medications and indications alkalosis decreases transpulmonary pressure, increased Vt increases alveolar ventilation and CO2 elimination, PEEP recruits alveoli to improve • Fluids/fluid resuscitation – types of fluids and indications Measured partial pressure of O2 in the Used to determine whether there is an blood (75-100mmHg) abnormality with oxygenation oxygenation. When compared with invasive ventilation, NIMV decreases • Acid/Base status, and correcting abnormalities the risk of ventilator associated pneumonia, lung injury, and pneumothorax. Calculated concentration of bicarbonate in Can be used to determine metabolic The patient must be able to maintain a patent airway and spontaneous • Cardiac arrhythmias – detection and acute management the blood (22-26meq/L) compensation. (pH<7.4 and HCO3>26) or breathing. • Acute management of liver and renal failure pH>7.4 and HCO3<24) = metabolic • Regardless, the decision to initiate mechanical or noninvasive ventilation • RAAS (Richmond-Agitation-Sedation Scale) compensation depends on the ABG and the determination of acid-base status. Arterial-Alveolar (A-A) Gradient Critical Care Curriculum The A-A gradient is a measure of the difference between The SIR-RFS has developed a critical care curriculum, which can be References alveolar and arterial O2 concentration and can narrow the accessed at http://rfs.sirweb.org/clinical-resources/critical-care-course/. Hantzidiamantis PJ, Amaro E. Physiology, Alveolar to Arterial Oxygen Gradient (Aa Gradient) [Updated 2019 Aug 3]. In: StatPearls [Internet]. Treasure Island (FL): differential for hypoxemia. The normal A-A gradient is 5- This curriculum was designed to reinforce clinical knowledge as residents StatPearls Publishing; 2020 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK545153/ 10mmHg progress through their diagnostic radiology curriuculum, and better prepare Critical Care Course [http://rfs.sirweb.org/clinical-resources/critical-care-course/] • In an ideal system, no gradient would exist since O2 residents to be comprehensive disease specialists. Emergency Resources: COVID-19 [https://www.sccm.org/Disaster] would flow freely across the alveolar membrane Mehta S, Hill NS: Noninvasive ventilation. Am J Respir Crit Care Med 2001, 163(2):540-577. • Causes of elevated gradients include shunt Additional course content is available at the Society of Critical Care Overview of Mechanical Ventilation [https://www.merckmanuals.com/professional/critical-care-medicine/respiratory-failure-and-mechanical- (pneumonia, atelectasis, cardiac), dead space Medicine (SCCM) at https://www.sccm.org/Home, including curriculum ventilation/overview-of-mechanical-ventilation] ventilation (PE, air embolism), and diffusion defect tailored for COVID-19 emergency response, at Rose L: Management of critically ill patients receiving noninvasive and invasive mechanical ventilation in the emergency department. Open Access Emerg Med (such as with interstitial lung defect) https://www.sccm.org/Disaster 2012, 4:5-15.