Continuous Negative Abdominal Pressure Research Articles

Continuous Negative Abdominal Pressure Reduces Ventilator-induced Lung Injury in a Porcine Model.

In supine patients with acute respiratory distress syndrome, the lung typically partitions into regions of dorsal atelectasis and ventral aeration ("baby lung"). Positive airway pressure is often used to recruit atelectasis, but often overinflates ventral (already aerated) regions. A novel approach to selective recruitment of dorsal atelectasis is by "continuous negative abdominal pressure." A randomized laboratory study was performed in anesthetized pigs. Lung injury was induced by surfactant lavage followed by 1 h of injurious mechanical ventilation. Randomization (five pigs in each group) was to positive end-expiratory pressure (PEEP) alone or PEEP with continuous negative abdominal pressure (-5 cm H2O via a plexiglass chamber enclosing hindlimbs, pelvis, and abdomen), followed by 4 h of injurious ventilation (high tidal volume, 20 ml/kg; low expiratory transpulmonary pressure, -3 cm H2O). The level of PEEP at the start was ≈7 (vs. ≈3) cm H2O in the PEEP (vs. PEEP plus continuous negative abdominal pressure) groups. Esophageal pressure, hemodynamics, and electrical impedance tomography were recorded, and injury determined by lung wet/dry weight ratio and interleukin-6 expression. All animals survived, but cardiac output was decreased in the PEEP group. Addition of continuous negative abdominal pressure to PEEP resulted in greater oxygenation (PaO2/fractional inspired oxygen 316 ± 134 vs. 80 ± 24 mmHg at 4 h, P = 0.005), compliance (14.2 ± 3.0 vs. 10.3 ± 2.2 ml/cm H2O, P = 0.049), and homogeneity of ventilation, with less pulmonary edema (≈10% less) and interleukin-6 expression (≈30% less). Continuous negative abdominal pressure added to PEEP reduces ventilator-induced lung injury in a pig model compared with PEEP alone, despite targeting identical expiratory transpulmonary pressure.

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

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.

高度肥満を伴う呼吸不全患者における持続腹部陰圧管理の有効性

【症例】32歳，男性。BMI 51.7の高度肥満あり。肺炎のため入院となり，人工呼吸器管理開始するも，呼吸管理に難渋しP/F比は50程度で推移しICUに入室した。経肺圧モニタリングを行い，高度肥満による胸郭コンプライアンス低下および腹腔内圧高値による横隔膜圧迫に抗するために高PEEPでの管理を行い，呼吸状態改善が得られた。また，高度肥満による横隔膜圧迫軽減目的に持続腹部陰圧管理を開始したところ，呼吸器同条件下における呼気終末経肺圧上昇を得ることができた。【考察】呼吸不全管理では人工呼吸器関連肺損傷を避けることが重要であり，その中心となるのが肺保護換気とopen lung戦略である。高度肥満患者では腹腔内圧高値のため，横隔膜が圧迫され肺内外圧差が下降することで肺胞虚脱が助長される。本症例では持続腹部陰圧管理により腹腔内圧が低下し，同条件下でも呼気終末の経肺圧を上昇させることが観察された。本現象は無気肺を改善させ，open lungに有利に働くと考えられる。

Use of Vacuum-Assisted Closure in the Management of Colostomy

Background: This article is the first report of the simultaneous use of vacuum-assisted closure (VAC) therapy and an oral tube applied as a life-saving treatment for colostomy dehiscence to avoid fecal contamination. Case Presentation: A 75-year-old female was admitted to our surgical unit in 2012 for knee trauma caused by an accidental fall at home. Surgery for lysis of adhesions, left colectomy, colorectal anastomosis, and protective ileostomy was performed initially for sigmoidovaginal fistula. Vacuum-assisted closure therapy (applying continuous negative abdominal pressure) was used after median wound dehiscence and a parastomal abscess that caused the necrosis of the skin and subcutaneous tissue surrounding the colostomy. Conclusion: The application of a negative pressure is a novel approach to colostomy dehiscence and complicated abdominal wound management and can lead to complete abdominal wound closure and finally to apply a standard plate for colostomy bag.

Continuous negative abdominal distension augments recruitment of atelectatic lung*

In acute lung injury, atelectasis is common and frequently develops in the dependent and diaphragmatic regions. Attempts to recruit lung with positive pressure constitute a major aim in the management of acute respiratory distress syndrome but are associated with overdistension and injury in nonatelectatic regions. To test the hypothesis that continuous negative abdominal pressure using an iron lung would augment positive end-expiratory pressure in recruiting atelectatic lung. An in vivo rabbit model of ventilator-induced lung injury was used in which a recruitment maneuver followed by positive end-expiratory pressure (110 cm H2O) had no effect on oxygenation. Addition of sustained continuous negative abdominal pressure (-5 cm H2O) to the positive end-expiratory pressure significantly increased the end-expired lung volume and PaO2 but impaired ventricular preload and cardiac output (suggested by echocardiography). Addition of transient (15 mins) continuous negative abdominal pressure resulted in comparable and lasting (60 mins) increases in PaO2. Sustained, but not transient, continuous negative abdominal pressure was associated with hemodynamic depression and lactic acidosis, which appeared (illustrative echocardiography, n = 2) to be caused by decreased cardiac preload. Computerized tomography (n = 2) suggested that continuous negative abdominal pressure was an effective adjunct to positive end-expiratory pressure for recruiting atelectasis in dependent and diaphragmatic regions. In surfactant-depleted but noninjured lungs, sustained continuous negative abdominal pressure augmented lung recruitment and oxygenation in the setting of higher (but not lower) levels of positive end-expiratory pressure and reduced central venous oxygenation. Continuous negative abdominal pressure may be a potential adjunct to positive end-expiratory pressure in the recruitment of diaphragmatic atelectasis. The approach ultimately might be useful when ceilings exist on the level of desired positive end-expiratory pressure.

A novel approach to severe acute pancreatitis in sequential liver-kidney transplantation: the first report on the application of VAC therapy

This work is the first report of vacuum-assisted closure (VAC) therapy applied as a life-saving surgical treatment for severe acute pancreatitis occurring in a sequential liver- and kidney-transplanted patient who had percutaneous biliary drainage for obstructive "late-onset" jaundice. Surgical exploration with necrosectomy and sequential laparotomies was performed because of increasing intra-abdominal pressure with hemodynamic instability and intra-abdominal multidrug-resistant sepsis, with increasingly difficult abdominal closure. Repeated laparotomies with VAC therapy (applying a continuous negative abdominal pressure) enabled a progressive, successful abdominal decompression, with the clearance of infection and definitive abdominal wound closure. The application of a negative pressure is a novel approach to severe abdominal sepsis and laparostomy management with a view to preventing compartment syndrome and fatal sepsis, and it can lead to complete abdominal wound closure.

Continuous negative abdominal pressure decreases intra-abdominal and central venous pressure in ICU patients

We set out to investigate whether continuous negative abdominal pressure (CNAP) might be used to decrease abdominal pressure. We investigated the effects of CNAP on both intra-abdominal pressure (IAP) and central venous pressure (CVP) on 30 consecutive patients admitted to our ICU (age 62 ± 14 years, BMI 26.3 ± 4, SAPS II 40.4 ± 18). Patients with severe hemodynamic instability and/or with recent laparotomy were not studied. Measurements included bladder pressure as an index of IAP, CVP, invasive mean arterial pressure (APm) and heart rate (HR). Following baseline measurements (Basal), CNAP (Life Care – Nev 100, Respironics) was applied on the abdomen at three levels: CNAP =, CNAP -5 and CNAP -10, corresponding to negative pressure equal to baseline IAP, 5 or 10 cmH2O lower than CNAP =, respectively. Results are as presented in Table ​Table11. Table 1 CVP was correlated with IAP (R2 = 0.790, P < 0.001, multiple linear regression). Given these results, we conclude that CNAP decreases IAP and CVP; the higher the negative pressure applied, the greater the changes. CVP decreases possibly because of a blood shift from the intrathoracic compartment.

Effects of continuous negative abdominal pressure on intrathoracic blood shift with and without increased intra-abdominal pressure: experimental study

We set out to investigate whether continuous negative abdominal pressure (CNAP) may produce blood shift from the intrathoracic compartment, and whether this effect would be influenced by abdominal pressure. We investigated eight sedated, paralysed and mechanically ventilated pigs (19.4 ± 4 kg). Blood shift was assessed by measuring intrathoracic blood volume (ITBV; PiCCO Pulsion), and central venous pressure (CVP). Measurements were taken before (Pre), a few seconds and 15 min after CNAP (-20 cmH2O; Life Care – Nev 100, Respironics) was applied on the abdomen (CNAP 1 and CNAP 2, respectively), and after CNAP was relieved (Post). The sequence of measurements was taken with and without abdominal hypertension. This was induced by means of helium (He) insufflation targeted to a value of 25 mmHg (24.7 ± 5.5 direct peritoneal measurement), corresponding to a bladder pressure of 29 ± 4 cmH2O. Basal and He measurements were randomised with respect to time. Results are shown in Table ​Table11. Table 1 CVP was correlated with ITBVI (R2 = 0.818, P < 0.001, multiple linear regression). We conclude that CNAP induces a blood shift from the intrathoracic compartment. Blood shift is greater without abdominal hypertension.

Physiologic effects of externally applied continuous negative abdominal pressure for intra-abdominal hypertension.

To determine the ability of an externally applied continuous negative abdominal pressure device (CNAP) to reverse the effects of elevated intra-abdominal pressure on the central nervous and cardiovascular systems. Anesthetized, ventilated swine had catheters placed for measurement of intra-abdominal (IAP), intracranial (ICP), central venous, pulmonary artery, pulmonary artery occlusion, mean arterial, peak inspiratory, inferior vena cava, and femoral vein pressures. After the animals stabilized, baseline measurements were obtained. IAP was increased by incrementally instilling an isosmotic polyethylene glycol solution into the peritoneal cavity until it was 25 mm Hg above baseline. IAP was maintained at 25 mm Hg above baseline for 2 hours. CNAP was then applied for 2 hours. All parameters were remeasured 30 minutes after each increase in IAP, at 2 hours after attaining maximum IAP, and lastly at 2 hours after abdominal decompression. Cardiac index was maintained near baseline by volume expansion. Elevation of IAP to 25 mm Hg above baseline for 2 hours caused increases (p<0.05) in central venous pressure (10.3+/-0.9 to 15.2+/-1.7), inferior vena cava pressure (13.0+/-1.0 to 29.5+/-1.5), femoral vein pressure (13.5+/-0.5 to 33.3+/-1.3), ICP (10.6+/-1.5 to 21.0+/-1.5), and peak inspiratory pressure (18.3+/-0.3 to 34.2+/-1.0). The mean arterial pressure (106.3+/-3.5 to 125.8+/-3.4), pulmonary artery pressure (24.3+/-2.3 to 31.3+/-1.7), and pulmonary artery occlusion pressure rose (12.3+/-0.9 to 17.5+/-3.5), but not significantly. Cardiac index (3.3+/-0.5 to 3.4+/-0.4) remained essentially unchanged. CNAP significantly (p<0.05) decreased IAP (30.7+/-1.3 to 18.2+/-1.3), central venous pressure (15.2+/-1.7 to 12.4+/-2.1), inferior vena cava (29.5+/-1.5 to 19.2+/-1.3), and ICP (21.0+/-1.5 to 16.2+/-1.3). Pulmonary artery occlusion pressure (17.5+/-3.5 to 15.0+/-3.1) and peak inspiratory pressure (34.2+/-1.0 to 29.7+/-1.1) decreased, but not significantly. Acutely elevated IAP causes a significant increase in ICP and impaired cardiovascular and pulmonary function. Abdominal decompression remains the standard of care for abdominal compartment syndrome. However, in patients in whom an increased IAP does not require surgical decompression, the results of this study suggest that externally applied CNAP may be of value.

Treatment of intracranial hypertension using nonsurgical abdominal decompression.

Elevated intra-abdominal pressure (IAP) increases intracranial pressure (ICP) and reduces cerebral perfusion pressure (CPP). We evaluated a nonsurgical means of reducing IAP to reverse this process. Swine with a baseline ICP of 25 mm Hg produced by an intracranial balloon catheter were studied. In group 1 (n = 5), IAP was increased by 25 mm Hg. Continuous negative abdominal pressure (CNAP) was then applied. Group 2 (n = 4) had neither IAP elevation nor CNAP. Group 3 (n = 4) had CNAP without IAP elevation. Elevation of IAP by 25 mm Hg above baseline led to deleterious changes in ICP (25.8+/-0.8 to 39.0+/-2.8; p < 0.05) and CPP (85.2+/-2.0 to 64.8+/-2.6; p < 0.05). CNAP led to a reduction in IAP (30.2+/-1.2 to 20.4+/-1.3; p < 0.05) and improvements in cerebral perfusion (ICP, 33+/-2.7; CPP, 74.4+/-1.2; both p < 0.05). Group 2 had stable ICP (25.8+/-0.25 to 28.7+/-1.7; p > 0.05) and CPP (80.8+/-1.4 to 80.5+/-1.8; p > 0.05). In group 3, CNAP decreased cardiac index (2.9+/-0.2 to 1.1+/-0.4; p < 0.05), mean arterial pressure (105.2+/-4.0 to 38.2+/-12.0; p < 0.05), and CPP (74.2+/-4.7 to 14.5+/-12.2; p < 0.05). Elevations in IAP led to increased ICP and decreased CPP. CNAP ameliorated these intracranial disturbances. With normal IAP, CNAP impaired cerebral perfusion.

The Physiologic Effects of Externally Applied Continuous Negative Abdominal Pressure for Intra-abdominal Hypertension

s Of Papers To Be Presented At The Joint Meeting Of The American Association For The Surgery Of Trauma (Fifty-Eight Annual Meeting) And The Trauma Association Of Canada, September 24-26, 1998, The Renaissance Harborplace Hotel, Baltimore, Maryland