American Journal of Emergency Medicine xxx (2014) xxx–xxx
Contents lists available at ScienceDirect
American Journal of Emergency Medicine journal homepage: www.elsevier.com/locate/ajem
Case Report
Is abdomen release really necessary for prone ventilation in acute respiratory distress syndrome?☆ ,☆☆ ,★ ,★★ Abstract Prone ventilation for refractory acute respiratory distress syndrome (ARDS) mandates free abdomen by rolls in between chest wall and pelvic bones for better ventilation and control of airway pressure. We observed that, in patients with severe ARDS, prone ventilation with movable free abdomen produced high plateau pressure reduced by applying simple support to abdominal wall. Here, we have proposed a possible hypothesis to explain the paradoxical event in this particular group of patients. The increased alveolar volume in prone position is counteracted by reduction in rib cage diameter caused by weight of abdomen. In patients with severe ARDS in prone position, gravitational pressure transmits through abdominal support, resulting in better chest wall expansion and leading to more oxygenation and opening of the alveoli in ventral lung along with the dorsal lung portion that is usually better ventilated in prone position. There is no clinical trial regarding this particular observation. We suggest randomized trials to prove our observational findings. Prone ventilation strategy is mainly used for severe and refractory ARDS. It requires higher sedation and muscle relaxants to control the airway pressure and asynchrony. Generally, in prone position, the abdomen is kept free for better ventilation and control of airway pressures that are often elevated in ARDS. We present a case of ARDS where free abdomen in prone position produced high airway pressures leading to difficulty in ventilation, whereas applying abdominal support improved ventilation with lowering of plateau pressures. We hypothesized a mechanism to explain the event. After obtaining consent, we wish to report such a fact. A 32-year-old man was admitted to trauma intensive care unit with abdominal solid organ injuries for monitoring purposes. He required intubation for desaturation unable to manage by venturi mask oxygen therapy. Over the course of illness, he developed severe refractory ARDS. It was so severe that conventional ventilation failed to maintain oxygenation as well as ventilation. Prone ventilation strategy was decided as a rescue measure. Our intensive care unit staff are well trained to do this kind of position. The patient was made prone in coordinated fashion with taking care of eyes, pressure points, and tube lines while keeping the abdomen wall free. We observed an abnormal finding in ventilator parameters and graphs when abdomen was kept free between 2 rolls at chest and iliac crest. The patient with free abdomen prone position had a very high plateau pressure in ☆ Author contributions: KDS: concept, case conduction, manuscript writing; SS: concept, manuscript writing; RA: manuscript editing; SS: manuscript review and editing. ☆☆ Conflicting interest: none. ★ Source of support: none. ★★ Presentation at a meeting: none.
volume-controlled ventilation. Pressure went up to 46 to 50 mm Hg (Fig. 1). Lung protective strategy by reducing tidal volume with increasing respiration rate decreased plateau pressure a little. Arterial blood gas analysis also did not improve in terms of partial pressure of oxygen with high PaCO2 along with a reducing trend of mean arterial blood pressure on the other hand. We were frequently checking the rolls’ position to ensure that they were not compressing the abdomen to hamper diaphragmatic movement. During manipulation for position in prone, we noticed that, when the abdominal free part is supported, the ventilator plateau pressure was reduced to 32 to 38 from 46 to 50 mm Hg (Fig. 2). We kept the patient in prone position with abdomen supported further (Fig. 3). Arterial blood gas (ABG) after 2 hours of this position demonstrated improved PaO2 and reduced PaCO2 comparatively. Mean arterial blood pressure also improved. He was ventilated in prone position for an average of 10 hours for 4 days. However, he went into septic shock with multiorgan failure and died later on. Abdominal wall is usually kept free by supporting rolls or bolsters placed on thorax and iliac crest. External pressure on the abdominal wall can increase intraabdominal pressure in prone position. This increased intraabdominal pressure compromises respiration. The external pressure pushes the diaphragm upwards, resulting in decreased functional residual capacity, poor lung compliance, elevated peak airway pressure, and increased plateau airway pressures. Hence, we are generally concerned about keeping free abdomen in prone position. All the above phenomena are explainable in case of prone position with normal lung parenchyma. However, patients with severe ARDS have heterogeneous consolidation of bilateral lungs. In
Fig. 1. Ventilator parameters showing high plateau pressure of about 45 to 50 mm Hg in prone position with free abdomen.
0735-6757/© 2014 Elsevier Inc. All rights reserved.
Please cite this article as: Soni KD, et al, Is abdomen release really necessary for prone ventilation in acute respiratory distress syndrome?, Am J Emerg Med (2014), http://dx.doi.org/10.1016/j.ajem.2014.03.031
2
K.D. Soni et al. / American Journal of Emergency Medicine xxx (2014) xxx–xxx
Fig. 3. Patient in prone position with abdominal support.
prone position does not improve oxygenation in acute lung injury, supporting our observation. In conclusion, abdominal support during prone ventilation may improve alveolar recruitment; but larger clinical studies are warranted to prove our observation.
Fig. 2. Ventilator parameters showing reduced plateau pressure of 38 mm Hg in prone position with abdominal support.
such patients, pressure transmission may be altered. Patients with severe ARDS show decrease in chest wall compliance when they are put into the prone position from supine [1]. This decrease in compliance is caused partly by stiffening of the ventral chest wall so that ventilation becomes preferentially directed towards the dorsal regions. Total functional residual capacity (FRC) does not typically improve with prone positioning in ARDS [2]. Therefore, improvement either in regional FRC or in regional tidal volume distribution with better ventilation perfusion match more likely explains the improvement in oxygenation. Mure et al [3] demonstrated that abdominal distension increased the FRC in supine but not in prone abdomen. Supine position rib cage freely displaces outwards and moves in easily; but in prone positioning, rib cage movements are restricted. It is likely that abdomen release helps in better caudal displacement of the diaphragm in patients placed in prone. The increased lung volume in prone is counteracted by reduction in rib cage diameter caused by weight of abdomen. In patients with severe ARDS patient in prone position, pressure transmission through abdominal support helps in better chest wall expansion. This leads to more oxygenation and opening of alveoli in the ventral lung along with the dorsal lung portion that is usually better ventilated in prone position. Hence, more alveoli from dorsal and ventral part are recruited in ARDS lungs in prone position with abdominal support. Colmenaro-Ruiz et al [4] studied adolescent pigs and demonstrated that abdomen release in
Kapil Dev Soni, MD Sukhen Samanta, MD, PDCC Richa Aggarwal, MD Department of Anesthesia & Critical Care (Trauma Centre) JPNA Trauma Centre, AIIMS, New Delhi 110029 E-mail address: [email protected] Sujay Samanta, MD Department of Critical Care Medicine Sanjay Gandhi Post Graduate Institute of Medical Sciences Luckow, India, 226014 http://dx.doi.org/10.1016/j.ajem.2014.03.031
References [1] Pelosi P, Tubiolo D, Mascheroni D, Vicardi P, Crotti S, Valenza F, et al. Effects of the prone position on respiratory mechanics and gas exchange during acute lung injury. Am J Respir Crit Care Med 1998;157:387–93. [2] Guerin C, Badet M, Rosselli S, Heyer L, Sab JM, Langevin B, et al. Effects of prone position on alveolar recruitment and oxygenation in acute lung injury. Intensive Care Med 1999;25:1222–30. [3] Mure M, Glenny RW, Domino KB, Hlastala MP. Pulmonary gas echange improves in the prone position with abdominal distension. Am J Respir Crit Care Med 1998;157:1785–90. [4] Colmenaro- Ruiz M, Guzman DPG, Jinenez-Quintana MM, Fernandez -Mondejar E. Abdomen release in prone position does not improve oxygenation in experimental model of acute lung injury. Intensive Care Med 2001;27:566–73.
Please cite this article as: Soni KD, et al, Is abdomen release really necessary for prone ventilation in acute respiratory distress syndrome?, Am J Emerg Med (2014), http://dx.doi.org/10.1016/j.ajem.2014.03.031
Contents lists available at ScienceDirect
American Journal of Emergency Medicine journal homepage: www.elsevier.com/locate/ajem
Case Report
Is abdomen release really necessary for prone ventilation in acute respiratory distress syndrome?☆ ,☆☆ ,★ ,★★ Abstract Prone ventilation for refractory acute respiratory distress syndrome (ARDS) mandates free abdomen by rolls in between chest wall and pelvic bones for better ventilation and control of airway pressure. We observed that, in patients with severe ARDS, prone ventilation with movable free abdomen produced high plateau pressure reduced by applying simple support to abdominal wall. Here, we have proposed a possible hypothesis to explain the paradoxical event in this particular group of patients. The increased alveolar volume in prone position is counteracted by reduction in rib cage diameter caused by weight of abdomen. In patients with severe ARDS in prone position, gravitational pressure transmits through abdominal support, resulting in better chest wall expansion and leading to more oxygenation and opening of the alveoli in ventral lung along with the dorsal lung portion that is usually better ventilated in prone position. There is no clinical trial regarding this particular observation. We suggest randomized trials to prove our observational findings. Prone ventilation strategy is mainly used for severe and refractory ARDS. It requires higher sedation and muscle relaxants to control the airway pressure and asynchrony. Generally, in prone position, the abdomen is kept free for better ventilation and control of airway pressures that are often elevated in ARDS. We present a case of ARDS where free abdomen in prone position produced high airway pressures leading to difficulty in ventilation, whereas applying abdominal support improved ventilation with lowering of plateau pressures. We hypothesized a mechanism to explain the event. After obtaining consent, we wish to report such a fact. A 32-year-old man was admitted to trauma intensive care unit with abdominal solid organ injuries for monitoring purposes. He required intubation for desaturation unable to manage by venturi mask oxygen therapy. Over the course of illness, he developed severe refractory ARDS. It was so severe that conventional ventilation failed to maintain oxygenation as well as ventilation. Prone ventilation strategy was decided as a rescue measure. Our intensive care unit staff are well trained to do this kind of position. The patient was made prone in coordinated fashion with taking care of eyes, pressure points, and tube lines while keeping the abdomen wall free. We observed an abnormal finding in ventilator parameters and graphs when abdomen was kept free between 2 rolls at chest and iliac crest. The patient with free abdomen prone position had a very high plateau pressure in ☆ Author contributions: KDS: concept, case conduction, manuscript writing; SS: concept, manuscript writing; RA: manuscript editing; SS: manuscript review and editing. ☆☆ Conflicting interest: none. ★ Source of support: none. ★★ Presentation at a meeting: none.
volume-controlled ventilation. Pressure went up to 46 to 50 mm Hg (Fig. 1). Lung protective strategy by reducing tidal volume with increasing respiration rate decreased plateau pressure a little. Arterial blood gas analysis also did not improve in terms of partial pressure of oxygen with high PaCO2 along with a reducing trend of mean arterial blood pressure on the other hand. We were frequently checking the rolls’ position to ensure that they were not compressing the abdomen to hamper diaphragmatic movement. During manipulation for position in prone, we noticed that, when the abdominal free part is supported, the ventilator plateau pressure was reduced to 32 to 38 from 46 to 50 mm Hg (Fig. 2). We kept the patient in prone position with abdomen supported further (Fig. 3). Arterial blood gas (ABG) after 2 hours of this position demonstrated improved PaO2 and reduced PaCO2 comparatively. Mean arterial blood pressure also improved. He was ventilated in prone position for an average of 10 hours for 4 days. However, he went into septic shock with multiorgan failure and died later on. Abdominal wall is usually kept free by supporting rolls or bolsters placed on thorax and iliac crest. External pressure on the abdominal wall can increase intraabdominal pressure in prone position. This increased intraabdominal pressure compromises respiration. The external pressure pushes the diaphragm upwards, resulting in decreased functional residual capacity, poor lung compliance, elevated peak airway pressure, and increased plateau airway pressures. Hence, we are generally concerned about keeping free abdomen in prone position. All the above phenomena are explainable in case of prone position with normal lung parenchyma. However, patients with severe ARDS have heterogeneous consolidation of bilateral lungs. In
Fig. 1. Ventilator parameters showing high plateau pressure of about 45 to 50 mm Hg in prone position with free abdomen.
0735-6757/© 2014 Elsevier Inc. All rights reserved.
Please cite this article as: Soni KD, et al, Is abdomen release really necessary for prone ventilation in acute respiratory distress syndrome?, Am J Emerg Med (2014), http://dx.doi.org/10.1016/j.ajem.2014.03.031
2
K.D. Soni et al. / American Journal of Emergency Medicine xxx (2014) xxx–xxx
Fig. 3. Patient in prone position with abdominal support.
prone position does not improve oxygenation in acute lung injury, supporting our observation. In conclusion, abdominal support during prone ventilation may improve alveolar recruitment; but larger clinical studies are warranted to prove our observation.
Fig. 2. Ventilator parameters showing reduced plateau pressure of 38 mm Hg in prone position with abdominal support.
such patients, pressure transmission may be altered. Patients with severe ARDS show decrease in chest wall compliance when they are put into the prone position from supine [1]. This decrease in compliance is caused partly by stiffening of the ventral chest wall so that ventilation becomes preferentially directed towards the dorsal regions. Total functional residual capacity (FRC) does not typically improve with prone positioning in ARDS [2]. Therefore, improvement either in regional FRC or in regional tidal volume distribution with better ventilation perfusion match more likely explains the improvement in oxygenation. Mure et al [3] demonstrated that abdominal distension increased the FRC in supine but not in prone abdomen. Supine position rib cage freely displaces outwards and moves in easily; but in prone positioning, rib cage movements are restricted. It is likely that abdomen release helps in better caudal displacement of the diaphragm in patients placed in prone. The increased lung volume in prone is counteracted by reduction in rib cage diameter caused by weight of abdomen. In patients with severe ARDS patient in prone position, pressure transmission through abdominal support helps in better chest wall expansion. This leads to more oxygenation and opening of alveoli in the ventral lung along with the dorsal lung portion that is usually better ventilated in prone position. Hence, more alveoli from dorsal and ventral part are recruited in ARDS lungs in prone position with abdominal support. Colmenaro-Ruiz et al [4] studied adolescent pigs and demonstrated that abdomen release in
Kapil Dev Soni, MD Sukhen Samanta, MD, PDCC Richa Aggarwal, MD Department of Anesthesia & Critical Care (Trauma Centre) JPNA Trauma Centre, AIIMS, New Delhi 110029 E-mail address: [email protected] Sujay Samanta, MD Department of Critical Care Medicine Sanjay Gandhi Post Graduate Institute of Medical Sciences Luckow, India, 226014 http://dx.doi.org/10.1016/j.ajem.2014.03.031
References [1] Pelosi P, Tubiolo D, Mascheroni D, Vicardi P, Crotti S, Valenza F, et al. Effects of the prone position on respiratory mechanics and gas exchange during acute lung injury. Am J Respir Crit Care Med 1998;157:387–93. [2] Guerin C, Badet M, Rosselli S, Heyer L, Sab JM, Langevin B, et al. Effects of prone position on alveolar recruitment and oxygenation in acute lung injury. Intensive Care Med 1999;25:1222–30. [3] Mure M, Glenny RW, Domino KB, Hlastala MP. Pulmonary gas echange improves in the prone position with abdominal distension. Am J Respir Crit Care Med 1998;157:1785–90. [4] Colmenaro- Ruiz M, Guzman DPG, Jinenez-Quintana MM, Fernandez -Mondejar E. Abdomen release in prone position does not improve oxygenation in experimental model of acute lung injury. Intensive Care Med 2001;27:566–73.
Please cite this article as: Soni KD, et al, Is abdomen release really necessary for prone ventilation in acute respiratory distress syndrome?, Am J Emerg Med (2014), http://dx.doi.org/10.1016/j.ajem.2014.03.031
