key: cord-0895306-yt0lafin authors: McGurk, Kevin; Riveros, Toni; Johnson, Nicholas; Dyer, Sean title: A primer on proning in the emergency department date: 2020-07-04 journal: J Am Coll Emerg Physicians Open DOI: 10.1002/emp2.12175 sha: 25de3427e5ebe3f3d6e8b58aede6b4d2d52c4ce6 doc_id: 895306 cord_uid: yt0lafin Historically, the prone position was used almost exclusively in the ICU for patients suffering from refractory hypoxemia due to acute respiratory distress syndrome (ARDS). Amidst the severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) pandemic, however, this technique has been increasingly utilized in settings outside of the ICU, particularly in the emergency department. With emerging evidence that patients diagnosed with COVID‐19 who are not intubated and mechanically ventilated may benefit from the prone position, this strategy should not be isolated to only those with critical illness. This is a review of the pertinent physiology and evidence supporting prone positioning along with a step‐by‐step guide meant to familiarize those who are not already comfortable with the maneuver. Placing a patient in the prone position helps to improve ventilation‐perfusion matching, dorsal lung recruitment, and ultimately gas exchange. Evidence also suggests there is improved oxygenation in both mechanically ventilated patients and those who are awake and spontaneously breathing, further reinforcing the utility of the prone position in non‐ICU settings. Given present concerns about resource limitations because of the pandemic, prone positioning has especially demonstrable value as a technique to delay or even prevent intubation. Patients who are able to self‐prone should be directed into the ''swimmer's position'' and then placed in reverse Trendelenburg position if further oxygenation is needed. If a mechanically ventilated patient is to be placed in the prone position, specific precautions should be taken to ensure the patient's safety and to prevent any unwanted sequelae of prone positioning. Acute onset: within 1 week of known clinical insult or new/worsening respiratory symptoms. Chest imaging Bilateral opacities not fully explained by effusions, lobar/lung collapse or nodules seen on chest radiograph or CT. Etiology of edema Not fully explained by other causes such as cardiac failure or fluid overload. Severe ARDS 100 mm Hg or less PEEP, positive end-expiratory pressure; PaO 2 ; partial pressure of arterial oxygen; FiO 2 , fraction of inspired oxygen; ARDS, acute respiratory distress syndrome; CT, computed tomography commonly deployed in the ED, including the prone position. This is especially true as prone positioning has been increasingly utilized in awake, spontaneously breathing patients. 3, 4 Although there are growing data to support the early use of prone positioning in patients with coronavirus disease 2019 (COVID- 19) , many emergency physicians may be unfamiliar with the maneuver or how to successfully utilize it. This article is intended as a primer on both the literature behind prone positioning and its safe application in EDs unaccustomed to its use. The mechanism underlying the beneficial effects of prone positioning has become clearer as the understanding of normal and abnormal lung physiology has evolved. While in the supine position under normal conditions, the lung parenchyma is subject to the forces of gravity and constrained by the anatomical shape of the thorax. During inspiration, recruited alveoli are inflated and gas exchange occurs. 5 The magnitude of lung ventilation is affected by the degree of inflation at both the level of the individual alveolus as well as the sum expansion of the entire lung. In the supine position, alveoli in the most dependent dorsal regions are often collapsed due to compression by overlying lung tissue. 6 Further compression of these regions occurs from weight placed on lung tissue by the heart and abdomen. ARDS is an acute, inflammatory lung injury defined by the Berlin criteria as shown in Table 1 . 7 This syndrome is known to lead to hypoxemia, diminished lung aeration, and edema. The compressive effects of supine positioning are magnified in lung tissue affected by ARDS because of this edema and the corresponding increased weight of lung parenchyma. 6 This results in less alveolar expansion in dorsal regions as compared to those in the ventral areas and subsequently less gas exchange occurs in these regions. This has been corroborated by imaging studies of patients with ARDS, which have documented dense consolidation in the dorsal lung regions when patients are supine. 6, 8 Because the dorsal regions of the lung contain more lung tissue as compared to the ventral regions, prone positioning improves ventilation by allowing for a more homogenous distribution of compressional forces on alveoli thereby improving ventilation and oxygenation. 5, 6, 8 Perfusion in the lungs is also greater in dorsal regions compared with ventral regions even while prone, and the combination of increased recruitment in these dorsal regions with greater perfusion leads to improved ventilation-perfusion matching and improvement in hypoxemia ( Figure 1 ). 5,6,8 The effect of the prone position on alveolar size at functional residual capacity (FRC) and FRC plus tidal volume (VT). In the supine posture, at FRC, the most dependent alveoli are small because of higher pleural pressures, compression from the heart, and extrinsic compression from abdominal contents as compared with the prone posture. During tidal breathing, the distribution of local ventilation is more uniform in the prone posture because the alveolar volumes are more uniform at the initiation of each breath. This allows tidal volumes to be more evenly distributed throughout the lung, leading to less alveolar stress and lung injury. As prone positioning has been primarily studied and applied in patients with ARDS, it was traditionally reserved for intubated and mechanically ventilated patients with moderate to severe disease. 6, [8] [9] [10] 17, 18 With emerging evidence that patients diagnosed with COVID-19 who are not intubated may benefit, this maneuver should not be isolated to only those with critical illness. 3, 4, 15 Although there are other disease states for which prone positioning has been used successfully, including non-ARDS associated acute hypoxemic respiratory failure and pediatric bronchiolitis, this is significantly less studied and should not be routinely used in the ED without specialty consultation. 19, 20 There is no general consensus on absolute contraindications to For patients who cannot self-prone, 5 or more staff members will usually be required to safely turn the patient with 2 on each side and 1 at the head of the bed. This maneuver should be practiced before implementation in your department to ensure the safety of the patient and staff members. With the necessary staff in place, the following steps should be followed 21-26 : 1. Disconnect or cap all non-essential lines and medical devices. Secure all remaining lines, drains, and tubes as necessary. Ensure there is adequate tubing length to allow for patient repositioning. Affix any urinary catheter to the medial leg. (Figure 4) . If there is an insufficient response in oxygenation after proning, consider adding a larger degree (20 to 30 degrees or more) of vertical tilt/reverse Trendelenburg. [27] [28] [29] In limited studies, oxygenation has been shown to improve with the combination of both prone and upright positioning. Although proning in reverse Trendelenburg has been the subject of less-dedicated scholarship, it is also an easily executed and low-risk adjustment to trial. Existing research shows little or no effect on patient hemodynamics when adding this vertical tilt to the prone position. If a patient has unilateral or asymmetric lung disease, lateral positioning (starting with the less-diseased side down) is a reasonable alternative. For beds likely to be used for patient proning (ie, a high acuity/resuscitation portion of the ED, ward for patients with COVID-19, etc) consider placing a second top sheet prior to the patient using the bed. When a patient cannot self-prone, the lower of the 2 sheets can then serve as a''slide sheet'' reducing the number of steps necessary to safely position him or her. EDs are likely to have neither the mattresses nor headrests specific to prone positioning that might be found in ICUs or operating rooms. As such, ED staff must remain mindful of anatomic regions at greatest risk for pressure damage or nerve injury. [22] [23] [24] [25] [26] This is especially true in sedated or paralyzed patients. Specific attention should be paid to the nose and eyes, breasts, elbows/cubital tunnel, pelvis, and the dorsum of the foot. Patients with silicone breast implants may be at increased risk for breast tissue damage or necrosis in the prone position. 30 For patients who require central venous access or arterial monitoring, consider insertion sites that are less likely to occlude and will remain more accessible for medication administration or blood draws once prone. 22 proper equipment, preparation, and personnel it can be done safely either via ground or aeromedical transport over long distances with few or no complications. [37] [38] [39] [40] Prone positioning, in the appropriate clinical context, has been shown to be a safe and efficacious maneuver. Once relegated exclusively to the ICU for those with critical illness, prone positioning can be performed in the ED for both awake, spontaneously breathing patients and those requiring mechanical ventilation. As the medical community navigates the unique challenges posed by the COVID-19 pandemic, prone positioning represents a readily implemented and potentially beneficial treatment option for hypoxic patients in the ED. Kevin McGurk MD https://orcid.org/0000-0002-4843-6837 Improved oxygenation in patients with acute respiratory failure: the prone position A Novel coronavirus from patients with pneumonia in China Efficacy and safety of early prone positioning combined with HFNC or NIV in moderate to severe ARDS: a multi-center prospective cohort study Lower mortality of COVID-19 by early recognition and intervention: experience from Jiangsu Province Gas exchange in the prone posture Efficacy of prone position in acute respiratory distress syndrome patients: a pathophysiology-based review Acute respiratory distress syndrome Prone positioning in acute respiratory distress syndrome. Semin Respir Critl Care Med Effect of mechanical ventilation in the prone position on clinical outcomes in patients with acute hypoxemic respiratory failure: a systematic review and meta-analysis Prone positioning in severe acute respiratory distress syndrome Treatment of ARDS with prone positioning Guidelines on the management of acute respiratory distress syndrome Prone positioning improves oxygenation in spontaneously breathing nonintubated patients with hypoxemic acute respiratory failure: a retrospective study Respiratory parameters in patients with COVID-19 after using noninvasive ventilation in the prone position outside the intensive care unit Early self-proning in awake, non-intubated patients in the emergency department: a single ED's experience during the COVID-19 pandemic Early prone position at the emergency room in acute respiratory distress syndrome: a pilot study Prone position augments recruitment and prevents alveolar overinflation in acute lung injury Prone ventilation reduces mortality in patients with acute respiratory failure and severe hypoxemia: systematic review and meta-analysis Physiological effect of prone position in children with severe bronchiolitis: a randomized cross-over study (BRONCHIO-DV) Prone position for acute respiratory failure in adults Formal guidelines: management of acute respiratory distress syndrome The pragmatics of prone positioning Safe prone checklist: construction and implementation of a tool for performing the prone maneuver. Rev Bras Ter Intensiva Patient positioning in anaesthesia Guidance for Prone Positioning in Adult Critical Care. London: Intensive Care Society The prone position during surgery and its complications: a systematic review and evidence-based guidelines Short-term effects of combining upright and prone positions in patients with ARDS: a prospective randomized study Acute effects of upright position on gas exchange in patients with acute respiratory distress syndrome Positioning of patients with acute respiratory distress syndrome: combining prone and upright makes sense Bilateral breast necrosis after prone position ventilation Ultrasound-guided central venous catheterization in prone position Ultrasound-guided central venous catheterization in the prone position Reverse CPR: a pilot study of CPR in the prone position Optimizing prone cardiopulmonary resuscitation: identifying the vertebral level correlating with the largest left ventricle cross-sectional area via computed tomography scan Part 6: electrical therapies: automated external defibrillators, defibrillation, cardioversion, and pacing Cardiopulmonary resuscitation in adult patients in prone position Transport of a prone position acute respiratory distress syndrome patient Transport of mechanically ventilated patients in the prone position Safe long-distance interhospital ground transfer of critically ill patients with acute severe unstable respiratory and circulatory failure ARDS with severe hypoxiaaeromedical transportation during prone ventilation A primer on proning in the emergency department