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versão On-line ISSN 1982-4335
Rev. bras. ter. intensiva vol.23 no.2 São Paulo abr./jun. 2011
Francisco PraccaI; Alberto BiestroI; Jose GorrassiI; Marcelo DavidII; Franco SiminiII; Mario CancelaI
IUniversidad de la Republica Oriental
del Uruguay UDELAR Montevideo Uruguay
IIBiomechanical Engineering Center of the Medical and Engineering Colleges Universidad de la Republica Oriental del Uruguay UDELAR Montevideo Uruguay
This article describes a device for the reduction of intra-abdominal pressure. The device (ABDOPRE) includes a unique external servo-control mechanism, based on urinary bladder pressure measurement. The results of ABDOPRE use in the first four intra-abdominal hypertension patients are reported; the device resulted in a reduction of intra-abdominal pressure between 16% and 35% in 3 cases and in a paradoxical increase of the intra-abdominal pressure in an obese woman, likely due to inappropriate chamber size for the patient's anatomy. These results are promising and ABDOPRE may be useful in clinical practice.
Keywords: Abdominal cavity/physiopathology; Compartment syndromes; Monitoring, physiologic/instrumentation; Monitoring, physiologic/methods; Case reports
Intra-abdominal hypertension (IAH) and abdominal compartment syndrome (ACS) are frequent in critically ill patients and are independently associated with increased morbidity and mortality.(1) Intra-abdominal pressures (IAP) above 20 mmHg have a negative impact on both intra- and extra-abdominal organ perfusion.(2) This manuscript reports on a prototype device (ABDOPRE) able to generate a negative pressure over the patient's abdomen, aimed to reduce the IAP; it additionally reports on the preliminary medical experiences with this device. This device is proposed to provide controlled reduction of the IAP.
Since 2006, the Department of Intensive Care Medicine and the Biomedical Engineering group have been cooperating to build a device called ABDOPRE able to accomplish the proposed objectives (Figures 1, 2 and 3).(3) ABDOPRE is comprised of the following: 1) a vacuum pump (150 mmHg pressure, maximal flow 0.4 L/min, fed by a 6-Volt source and with 65 dB noise) plus connections; 2) a rigid and transparent chamber, adjustable to the skin; and 3) a pressure data acquisition and automated control system (servo-controlled) and a user's interface screen.(3) The IAP was continuously measured according to Balogh's(4) technique, using a 3-way intravesical catheter, keeping the urine output independent. The ABDOPRE software allows maintenance of the hypotensive therapy schedule. The ABDOPRE scan concomitantly displays the IAP and therapeutic target, allowing physicians to monitor both the device performance and patients' IAP. In contrast to the model described by Valenza et al.,(5) ABDOPRE has a servo-controlled pressure system, which uses the intravesical pressure as a control variable.
Informed consent was obtained from a patient's relative. The investigators played the role of healthy volunteers. The institution's Ethics Committee approved this study protocol.
The initial assay was conducted on a healthy volunteer achieving a -90-mmHg chamber pressure. During progressive negative pressures, the subject experienced considerable abdominal expansion. From -30 mmHg on, the subject reported some abdominal wall discomfort due to stretching; therefore, the test was discontinued. The test duration was 3 minutes. Upon completion of the test, the subject had an erythema on the chamber contact area.
ABDOPRE was tested in 4 patients: 2 female and 2 male. The mean age was 48.5 years (ranging from 18 to 78 years) (Table 1). Mean body weight was 74 Kg, and the mean APACHE II score was 22. The IAP was measured as millimeters of mercury (mmHg). All 4 patients had Grade I IAH. In 2 patients, the IAP dropped to 9 mmHg, with a delta intra-abdominal pressure (ΔIAP = IAPinitial IAPfinal) of -5 mmHg and -3 mmHg, respectively. Another patient displayed a drop from 12 mmHg to 10 mmHg, ΔIAP = -2 mmHg. The mean percent change was -25.3% (range 16-35%). In one patient, the IAP was increased by 38% over the baseline. This finding was an obese female patient (95 Kg) with a 34.9 body mass index (BMI) for whom the chamber was too small. This increased IAP was likely explainable by a 'ventosa effect', developed due to the inadequate proportion between the glass chamber and the abdominal wall. Therefore, the intra-abdominal volume was reduced due to intromission of part of the abdominal wall into the chamber; additionally, perhaps the chamber plus part of the abdominal wall represented an increased weight over the abdomen, resulting in this paradoxical effect on the IAP.
IAP reductions were obtained for all patients with -35 mmHg pressures, with the target achieved within the proposed time (10 minutes) and maintained for about 1 hour. No changes in mean blood pressure or heart rate were observed, and no arrhythmia was identified. The procedure was well tolerated, with no discomfort observed and no ventilator issue ascribable to pain. All patients were sedated (midazolam 0.083 mg/Kg/hour) and under analgesia (fentanyl 3 mcg/Kg/hour) as continuous infusion.
This article reports on a preliminary trial with a small number of cases. The performance of the device was acceptable and safe. In 3 of the 4 patients, IAP was reduced by about 25%. The fourth case had a paradoxical increase; the likely explanation was addressed earlier in this paper. This failure led to a chamber review; consequently, its diameter was increased to prevent this paradoxical effect. The initial prototype (Figure 2) would be inconvenient for obese patients. However, this should be considered as a developing device that remains to be improved. Its use according to appropriate research protocols will allow optimization of its performance and the user's interface and may potentially provide a clinical tool for the management of IAH.
1. Malbrain ML, Chiumello D, Pelosi P, Bihari D, Innes R, Ranieri VM, et al. Incidence and prognosis of intraabdominal hypertension in a mixed population of critically ill patients: a multiple-center epidemiological study. Crit Care Med. 2005;33(2):315-22. [ Links ]
2. Cullen DJ, Coyle JP, Teplick R, Long MC. Cardiovascular, pulmonary, and renal effects of massively increased intra-abdominal pressure in critically ill patients. Crit Care Med. 1989;17(2):118-21. [ Links ]
3. David M, Geido D, Pracca F, Sánchez G, Simini F, Zoppolo C. Negative pressure device for intraabdominal pressure reduction. J Phys. 2007;90:012035.[Conference Series] [ Links ].
4. Balogh Z, Jones F, D'Amours S, Parr M, Sugrue M. Continuous intra-abdominal pressure measurement technique. Am J Surg. 2004;188(6):679-84. [ Links ]
5. Valenza F, Irace M, Guglielmi M, Gatti S, Bottino N, Tedesco C, et al. Effects of continuous negative extra-abdominal pressure on cardiorespiratory function during abdominal hypertension: an experimental study. Intensive Care Med. 2005;31(1):105-11. [ Links ]
author: Conflicts of interest: This device, called
ABDOPRE, was projected by the institution's Departamento de Medicina Intensiva
y el Núcleo de Ingeniería Biomédica. This study was conducted at Universidad de la
República Oriental UDELAR Montevideo Uruguay.
Departamento de Medicina Intensiva Hospital de Clínicas- Universidad de la República
Av. Italia S/N, 11600
Montevideo - Uruguay
Conflicts of interest: This device, called ABDOPRE, was projected by the institution's Departamento de Medicina Intensiva y el Núcleo de Ingeniería Biomédica.
This study was conducted at Universidad de la República Oriental UDELAR Montevideo Uruguay.