scholarly journals Continuous negative abdominal pressure: mechanism of action and comparison with prone position

2018 ◽  
Vol 125 (1) ◽  
pp. 107-116 ◽  
Author(s):  
Takeshi Yoshida ◽  
Doreen Engelberts ◽  
Gail Otulakowski ◽  
Bhushan Katira ◽  
Niall D. Ferguson ◽  
...  
Keyword(s):  
Lung Injury ◽  
Prone Position ◽  
Mechanism Of Action ◽  
Respir Crit ◽  
Vertical Gradient ◽  
Lung Compliance ◽  
Pleural Pressure ◽  
Abdominal Pressure ◽  
Prone Positioning ◽  
Positive End Expiratory Pressure

We recently reported that continuous negative abdominal pressure (CNAP) could recruit dorsal atelectasis in experimental lung injury and that oxygenation improved at different transpulmonary pressure values compared with increases in airway pressure (Yoshida T, Engelberts D, Otulakowski G, Katira BH, Post M, Ferguson ND, Brochard L, Amato MBP, Kavanagh BP. Am J Respir Crit Care Med 197: 534–537, 2018). The mechanism of recruitment with CNAP is uncertain, and its impact compared with a commonly proposed alternative approach to recruitment, prone positioning, is not known. We hypothesized that CNAP recruits lung by decreasing the vertical pleural pressure (Ppl) gradient (i.e., difference between dependent and nondependent Ppl), thought to be one mechanism of action of prone positioning. An established porcine model of lung injury (surfactant depletion followed by ventilator-induced lung injury) was used. CNAP was applied using a plexiglass chamber that completely enclosed the abdomen at a constant negative pressure (−5 cmH2O). Lungs were recruited to maximal positive end-expiratory pressure (PEEP; 25 cmH2O) and deflated in steps of PEEP (2 cmH2O, 10 min each). CNAP lowered the Ppl in dependent but not in nondependent lung, and therefore, in contrast to PEEP, it narrowed the vertical Ppl gradient. CNAP increased respiratory system compliance and oxygenation and appeared to selectively displace the posterior diaphragm caudad (computerized tomography images). Compared with prone position without CNAP, CNAP in the supine position was associated with higher arterial partial pressure of oxygen and compliance, as well as greater homogeneity of ventilation. The mechanism of action of CNAP appears to be via selective narrowing of the vertical gradient of Ppl. CNAP appears to offer physiological advantages over prone positioning. NEW & NOTEWORTHY Continuous negative abdominal pressure reduces the vertical gradient in (dependent vs. nondependent) pleural pressure and increases oxygenation and lung compliance; it is more effective than prone positioning at comparable levels of positive end-expiratory pressure.

scholarly journals Comparison of pleural and esophageal pressure in supine and prone positions in a porcine model of acute respiratory distress syndrome

2020 ◽  
Vol 128 (6) ◽  
pp. 1617-1625 ◽  
Author(s):  
N. Terzi ◽  
S. Bayat ◽  
N. Noury ◽  
E. Turbil ◽  
W. Habre ◽  
...  
Keyword(s):  
Acute Respiratory Distress Syndrome ◽  
Respiratory Distress Syndrome ◽  
Respiratory Distress ◽  
Prone Position ◽  
Distress Syndrome ◽  
Porcine Model ◽  
Vertical Gradient ◽  
Esophageal Pressure ◽  
Pleural Pressure ◽  
Positive End Expiratory Pressure

In a porcine model of acute respiratory distress syndrome, we found that static end-expiratory esophageal pressure did not change significantly in prone position compared with supine position at any positive end-expiratory pressure (PEEP) tested between 5 and 20 cmH2O. Prone position was associated with an increased ventral pleural pressure and reduced end-expiratory dorsal-to-ventral pleural pressure (Ppl) vertical gradient, likely due to a more even distribution of mechanical forces over the chest wall.

scholarly journals Respiratory mechanical effects of surgical pneumoperitoneum in humans

2014 ◽  
Vol 117 (9) ◽  
pp. 1074-1079 ◽  
Author(s):  
Stephen H. Loring ◽  
Negin Behazin ◽  
Aileen Novero ◽  
Victor Novack ◽  
Stephanie B. Jones ◽  
...  
Keyword(s):  
Chest Wall ◽  
Respiratory System ◽  
Transpulmonary Pressure ◽  
Esophageal Pressure ◽  
Pleural Pressure ◽  
Abdominal Pressure ◽  
Positive End Expiratory Pressure ◽  
Before And After ◽  
Show Evidence ◽  
Obese Subjects

Pneumoperitoneum for laparoscopic surgery is known to stiffen the chest wall and respiratory system, but its effects on resting pleural pressure in humans are unknown. We hypothesized that pneumoperitoneum would raise abdominal pressure, push the diaphragm into the thorax, raise pleural pressure, and squeeze the lung, which would become stiffer at low volumes as in severe obesity. Nineteen predominantly obese laparoscopic patients without pulmonary disease were studied supine (level), under neuromuscular blockade, before and after insufflation of CO2 to a gas pressure of 20 cmH2O. Esophageal pressure (Pes) and airway pressure (Pao) were measured to estimate pleural pressure and transpulmonary pressure (Pl = Pao − Pes). Changes in relaxation volume (Vrel, at Pao = 0) were estimated from changes in expiratory reserve volume, the volume extracted between Vrel, and the volume at Pao = −25 cmH2O. Inflation pressure-volume (Pao-Vl) curves from Vrel were assessed for evidence of lung compression due to high Pl. Respiratory mechanics were measured during ventilation with a positive end-expiratory pressure of 0 and 7 cmH2O. Pneumoperitoneum stiffened the chest wall and the respiratory system (increased elastance), but did not stiffen the lung, and positive end-expiratory pressure reduced Ecw during pneumoperitoneum. Contrary to our expectations, pneumoperitoneum at Vrel did not significantly change Pes [8.7 (3.4) to 7.6 (3.2) cmH2O; means (SD)] or expiratory reserve volume [183 (142) to 155 (114) ml]. The inflation Pao-Vl curve above Vrel did not show evidence of increased lung compression with pneumoperitoneum. These results in predominantly obese subjects can be explained by the inspiratory effects of abdominal pressure on the rib cage.

scholarly journals Impact of Different Positive End-Expiratory Pressures on Lung Mechanics in the Setting of Moderately Elevated Intra-Abdominal Pressure and Acute Lung Injury in a Porcine Model

2021 ◽  
Vol 10 (2) ◽  
pp. 306
Author(s):  
Mascha O. Fiedler ◽  
Emilis Simeliunas ◽  
B. Luise Deutsch ◽  
Dovile Diktanaite ◽  
Alexander Harms ◽  
...  
Keyword(s):  
Acute Lung Injury ◽  
Lung Injury ◽  
Transpulmonary Pressure ◽  
Lung Compliance ◽  
Lung Mechanics ◽  
Lung Injury Score ◽  
Abdominal Pressure ◽  
Injury Score ◽  
Group A ◽  
Over Time

The effects of a moderately elevated intra-abdominal pressure (IAP) on lung mechanics in acute respiratory distress syndrome (ARDS) have still not been fully analyzed. Moreover, the optimal positive end-expiratory pressure (PEEP) in elevated IAP and ARDS is unclear. In this paper, 18 pigs under general anesthesia received a double hit lung injury. After saline lung lavage and 2 h of injurious mechanical ventilation to induce an acute lung injury (ALI), an intra-abdominal balloon was filled until an IAP of 10 mmHg was generated. Animals were randomly assigned to one of three groups (group A = PEEP 5, B = PEEP 10 and C = PEEP 15 cmH2O) and ventilated for 6 h. We measured end-expiratory lung volume (EELV) per kg bodyweight, driving pressure (ΔP), transpulmonary pressure (ΔPL), static lung compliance (Cstat), oxygenation (P/F ratio) and cardiac index (CI). In group A, we found increases in ΔP (22 ± 1 vs. 28 ± 2 cmH2O; p = 0.006) and ΔPL (16 ± 1 vs. 22 ± 2 cmH2O; p = 0.007), with no change in EELV/kg (15 ± 1 vs. 14 ± 1 mL/kg) when comparing hours 0 and 6. In group B, there was no change in ΔP (26 ± 2 vs. 25 ± 2 cmH2O), ΔPL (19 ± 2 vs. 18 ± 2 cmH2O), Cstat (21 ± 3 vs. 21 ± 2 cmH2O/mL) or EELV/kg (12 ± 2 vs. 13 ± 3 mL/kg). ΔP and ΔPL were significantly lower after 6 h when comparing between group C and A (21 ± 1 vs. 28 ± 2 cmH2O; p = 0.020) and (14 ± 1 vs. 22 ± 2 cmH2O; p = 0.013)). The EELV/kg increased over time in group C (13 ± 1 vs. 19 ± 2 mL/kg; p = 0.034). The P/F ratio increased in all groups over time. CI decreased in groups B and C. The global lung injury score did not significantly differ between groups (A: 0.25 ± 0.05, B: 0.21 ± 0.02, C: 0.22 ± 0.03). In this model of ALI, elevated IAP, ΔP and ΔPL increased further over time in the group with a PEEP of 5 cmH2O applied over 6 h. This was not the case in the groups with a PEEP of 10 and 15 cmH2O. Although ΔP and ΔPL were significantly lower after 6 hours in group C compared to group A, we could not show significant differences in histological lung injury score.

Cardiopulmonary Effects of Matching Positive End-Expiratory Pressure to Abdominal Pressure in Concomitant Abdominal Hypertension and Acute Lung Injury

2010 ◽  
Vol 69 (2) ◽  
pp. 375-383 ◽  
Author(s):  
Juliana Roberta da Silva Almeida ◽  
Fabio Santana Machado ◽  
Guilherme Paula Pinto Schettino ◽  
Marcelo Park ◽  
Luciano Cesar Pontes Azevedo
Keyword(s):  
Acute Lung Injury ◽  
Lung Injury ◽  
Abdominal Pressure ◽  
Positive End Expiratory Pressure ◽  
Abdominal Hypertension

scholarly journals Case series of acute peritoneal dialysis in the prone position for acute kidney injury during the Covid-19 pandemic: Prone to complications?

2021 ◽  
pp. 089686082098367
Author(s):  
Qandeel H Soomro ◽  
Vikramjit Mukherjee ◽  
Richard Amerling ◽  
Nina Caplin
Keyword(s):  
Acute Kidney Injury ◽  
Peritoneal Dialysis ◽  
Prone Position ◽  
Distress Syndrome ◽  
Respiratory Mechanics ◽  
Case Series ◽  
Kidney Injury ◽  
Abdominal Pressure ◽  
Prone Positioning ◽  
Respiratory System Compliance

Patients with kidney failure and acute respiratory distress syndrome (ARDS) requiring prone position have not been candidates for peritoneal dialysis (PD) due to concern with increased intra-abdominal pressure, reduction in respiratory system compliance and risks of peritoneal fluid leaks. We describe our experience in delivering acute PD during the surge in Covid-19 acute kidney injury (AKI) in the subset of patients requiring prone positioning. All seven patients included in this report were admitted to the intensive care unit with SARS-CoV-2 infection leading to ARDS, AKI and multisystem organ failure. All required renal replacement therapy, and prone positioning to improve ventilation/perfusion mismatch. All seven were able to continue PD despite prone positioning without any detrimental effects on respiratory mechanics or the need to switch to a different modality. Fluid leakage was noted in 71% of patients, but mild and readily resolved. We were able to successfully implement acute PD in ventilator-dependent prone patients suffering from Covid-19-related AKI. This required a team effort and some modifications in the conventional PD prescription and delivery.

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