Ali, J. and W. Qi (1992). "The cardiorespiratory effects of increased intra-abdominal pressure in diaphragmatic rupture." J Trauma 33(2): 233-7; discussion 237-9.

The cardiorespiratory effect of gastric herniation in diaphragmatic rupture with and without increased intra-abdominal pressure (produced by inflation of a pneumatic antishock garment [PASG] to an intraperitoneal pressure of 40 mm Hg) was studied in 16 anesthetized spontaneously breathing (80% oxygen) piglets. Four additional animals had similar measurements after PASG inflation but without diaphragmatic rupture. Arterial blood pressure (BP), cardiac output, arterial blood gases, position of the stomach relative to the diaphragm (as measured on fluoroscopy), and mortality were assessed. Gastric herniation without the PASG (group I: 8 animals) produced slight cardiorespiratory deterioration, with PO2 falling from a baseline measurement of 429 +/- 60 mm Hg to 316 +/- 5 mm Hg at 1 hour. Over this period pH decreased from 7.39 +/- 0.05 to 7.30 +/- 0.02 and PCO2 increased from 39 +/- 5 to 46 +/- 2 mm Hg. With PASG inflation (group II: 8 animals) PO2 decreased to a greater extent, from 410 +/- 30 mm Hg at baseline to 48 +/- 10 mm Hg by 1 hour; pH decreased from 7.38 +/- 0.06 to 6.8 +/- 0.2 and PCO2 increased from 39 +/- 4 to 88 +/- 6 mm Hg. Animals without diaphragmatic rupture (group III: 4 animals) showed a smaller decrease in PO2, from 480 +/- 34 mm Hg at baseline to 320 +/- 50 mm Hg by 1 hour after PASG inflation.(ABSTRACT TRUNCATED AT 250 WORDS)

Abdominal compartment syndrome is still a controversial entity. We report on a patient who developed the classical hemodynamic, respiratory, and renal changes of abdominal compartment syndrome after surgical intervention for blunt abdominal trauma. A decompressive laparotomy improved the situation dramatically.

Acute abdominal compartment syndrome has recently been shown to raise intracranial pressure (ICP). This may increase the risk of ischemic neuronal damage by decreasing cerebral perfusion pressure. We report the successful management of a patient with severe multisystem injury in whom abdominal decompression dramatically reduced high ICP unresponsive to medical measures.

Four patients are described in whom massive abdominal distension after laparotomy led to increased airway and central venous pressure and severely reduced urine output. All cases were associated with massive fluid resuscitation and operative findings were a grossly oedematous bowel with free fluid under pressure in the abdomen. These findings are consistent with the diagnosis of intra-abdominal compartment syndrome. In 1 case trauma was remote from the abdomen indicating that abdominal surgery or trauma may not be a prerequisite for the development of the condition. Recognition of the features of the condition is essential as it can only be treated by decompression of the abdominal contents.

Laparoscopic surgery generally is regarded as a safe procedure when a preset pressure is used in the carbon dioxide insufflator. However, a fixed pressure setting is not appropriate when insufflating a very large or a very small abdomen. Presently, extrapolation from the commonly used 15 mm Hg to an appropriate and safe pressure cannot be easily determined except by a crude trial and error method. We developed an anthropometric formula to calculate the total abdominal cavity capacity and the corresponding pressure necessary to obtain safe pneumoperitoneum. This anthropometric formula calculates the total abdominal capacity by measuring one diameter from the symphysis pubis to the xyphoid bone, a second diameter as half the initial measurement, and a third diameter by dividing the waist measurement (minus an estimated percentage of body fat) and dividing that product by pi. The product of the three diameters is then multiplied by a constant (K = 0.5). We studied prospectively 20 patients whose indications for laparoscopic surgery necessitated creation of a pneumoperitoneum. The patients were divided into two groups: group A (n = 10), patients who were observed with the intra-abdominal pressure fixed at 15 mm Hg while recording the amount of distension produced in the abdominal cavity during creation of the pneumoperitoneum; and group B (n = 10) in whom pneumoperitoneum was obtained based on the initial volume of carbon dioxide-insufflation previously calculated using our formula. Based on our observations, we conclude that this anthropometric formula can be used successfully in predicting a safe level of insufflation in relation to the patient's size.

The abdominal pressure is a hydrostatic one, which can be measured in the bladder, the rectum and the stomach. In physiologic conditions, the abdominal pressure is variable, with peaks as high as 100 to 200 mmHg at the time of defecation, cough. The increase in abdominal pressure elicited by abdominal distension or compression acts directly on the abdominal compartment, indirectly on the thoracic compartment, and modifies the circulation and the ventilation. Venous return is decreased as the inferior vena cava is compressed. The systemic resistances are also increased as the abdominal vessels are compressed. Therefore the circulation is mainly distributed to the superior part of the body. Although the cardiac output is decreased, the usual haemodynamic parameters remain in the normal range: arterial pressure is increased, heart rate is unchanged, central venous pressure is increased, cardiac failure is unusual. The abdominal distension is also responsible for a restrictive respiratory syndrome, mainly due to the ascension of the diaphragm. The compression of the abdominal content explains renal effects and the decreased diuresis. A sustained increase in abdominal pressure occurs in several clinical conditions. During coelioscopy, abdominal pressure is a under control and the cardiovascular effects are minor. Insufflation with CO2 carries the risk of hypercapnia, gas embolism and pneumothorax. During abdominal tamponade, anuria is directly related to the level of pressures. At an abdominal pressure over 25 mmHg, anuria is common and decompression becomes essential. The G suit increases arterial pressure either by elevating vascular resistances or increasing blood content in the upper part of the body. Therefore cardiac tolerance can be decreased especially in cardiac patients. The adverse effects of abdominal pressure can also be observed in case of peritoneal dialysis and ascites. The risk of regurgitation associated with an increased abdominal pressure must also be kept in mind. The abdominal pressure plays an important role in anaesthesia as well as in surgery. Therefore its measurement, which is easy, should become a routine.

HYPOTHESIS. Assessment of splanchnic perfusion by gastric intramucosal pH (pHi) adds to the information provided by systemic indicators of oxygen transport. SETTING. University Hospital level I trauma center. DESIGN. Prospective study in 20 critically ill trauma patients comparing pHi with base deficit, lactate, oxygen delivery, and oxygen consumption (indexed to body surface area), mixed venous oxygen saturation (Svo2), oxygen utilization coefficient, and arterial pH. All measurements were obtained at admission, 1, 2, 4, 8, 16, and 24 hours, or at death. MAIN OUTCOME MEASURES. Correlation of pHi with the measured systemic variables, prediction of organ dysfunction, development of multiple organ dysfunction syndrome, and mortality. RESULTS. There was a poor correlation between pHi and the systemic hemodynamic and oxygen transport variables. Patients with a low pHi (< 7.32) on admission who did not correct within the initial 24 hours had a higher mortality (50% vs. 0.0%, p = 0.03) and incidence of organ dysfunction (2.6 organs/patient vs. 0.62 organs/patient, p = 0.02) than those who did. Using logistic regression analysis, only pHi, base deficit, and Svo2 were significantly associated with mortality during the study period. At 24 hours, only pHi was different between patients who developed multiple organ dysfunction syndrome and those who did not. There was a threshold value for pHi (7.10) which identified those patients who would go on to develop multiple organ dysfunction syndrome. CONCLUSIONS. Uncorrected splanchnic malperfusion is associated with a higher incidence of organ dysfunction and mortality. Gastric tonometry supplements information provided by systemic indicators of oxygen transport during resuscitation of critically ill trauma patients.

An animal model was established to study the effects of elevated intra-abdominal pressure (IAP) on systemic and renal hemodynamics during laparoscopy. In a pilot study in five dogs, we simultaneously recorded carotid artery blood flow (CABF), carotid artery blood pressure (CABP), inferior vena caval pressure (IVCP), renal parenchymal blood flow, and IAP. The renal parenchymal blood flow was measured by a laser Doppler flowmetry (LDF) needle probe and the renal artery blood flow by an ultrasonic Doppler probe, both placed through laparotomy. The reliability and reproducibility of these two measurements at different renal perfusion pressures were documented. The established method was then used to assess the effects of increased IAP on renal hemodynamics during laparoscopy in six pigs. Pneumoperitoneum was achieved by insufflating the abdominal cavity with air. The LDF needle probe was inserted into the renal parenchyma laparoscopically. An increase in IAP from 0 to 40 mm Hg did not influence CABP. However, significant decreases in CABF were seen from 190.8 +/- 59.5 mL/min at 0 mm Hg IAP to 169 +/- 43.6 mL/min at 15 mm Hg. The CABF decreased in a linear fashion as IAP was increasing (correlation coefficient R = 0.976). Renal cortical blood flow (RCBF) decreased from 50.1 +/- 17.7 mL/min per 100 g at 0 mm Hg to IAP to 21.2 +/- 9.6 mL/min per 100 g of tissue at 15 mm Hg. There was an exponential correlation between IAP and RCBF (R = 0.897).(ABSTRACT TRUNCATED AT 250 WORDS)

OBJECTIVES: To compare measurements of intraabdominal pressure (IAP) via a naso-gastric tube with the previously validated technique of IAP measurement via a urinary bladder catheter. To examine an association between elevated IAP and oliguric acute renal failure. DESIGN: Simultaneous paired measurements of gastric and urinary bladder pressures in supine patients. SETTING: The general intensive care units of two London hospitals. PATIENTS: 141 Paired measurements of intragastric and urinary bladder pressures were obtained in 26 general intensive care patients. MEASUREMENTS AND RESULTS: With the patient lying supine, 50 ml of sterile water were instilled via manometer tubing into the stomach and bladder following drainage of each viscera. The mid-axillary line was used as the zero reference, and cavity pressures noted in centimeters of water (cmH2O) at end expiration. The results were compared using the technique of Bland and Altman. RESULTS: Gastric pressure may be approximately 2.5 cmH2O above or below urinary bladder pressure. Manometric measurement of the gastric pressure via a naso-gastric tube provides a simple, reliable, non-invasive technique of IAP measurement. IAP should be regularly monitored in patients with abdominal distension at risk of acute renal failure.

Intra-abdominal pressure (IAP) was indirectly measured, using a transurethral catheterization technique, in 20 client-owned dogs before and after elective ovariohysterectomy. Mean preoperative IAP was 4.50 +/- 0.44 cm H2O. Elective abdominal surgery caused significant elevations in mean postoperative IAP (mean 7.50 +/- 0.45 cm H2O, range 0 to 15 cm H2O) that persisted for at least 24 hours. However, the increase in IAP caused no clinically evident complications; thus, after elective abdominal surgery an elevation in IAP up to 15 cm H2O is to be expected. Intra-abdominal pressure was also measured in 20 consecutive clinical cases with gross abdominal distension, before or after laparotomy, or both. Included in this group were dogs with gastric dilation and volvulus, closed pyometra, hemoperitoneum, acute ascites, and diaphragmatic hernias. All dogs with gross abdominal distension had an elevated IAP (> or = 16 cm H2O) either before or after surgery. Severe elevations of IAP were associated with anuria in two dogs, necessitating surgical decompression; one with hemoperitoneum (47 cm H2O) and one after repair of a chronic diaphragmatic hernia (30 cm H2O).

The aim was to investigate possible relationships between activities of the individual muscles of the ventrolateral abdominal wall and the development of pressure within the abdominal cavity. Intra-muscular activity was recorded bilaterally from transversus abdominis, obliquus internus, obliquus externus and rectus abdominis with fine-wire electrodes guided into place using real-time ultrasound. Intra- abdominal pressure was measured intragastrically using a micro tip pressure transducer. Six males were studied during loading and movement tasks with varied levels of intra-abdominal pressure. During both maximal voluntary isometric trunk flexion and extension, transversus abdominis activity and intra-abdominal pressure remained constant, while all other abdominal muscles showed a marked reduction during extension. When maximal isometric trunk flexor or extensor torques were imposed upon a maximal Valsalva manoeuvre, transversus abdominis activity and intra-abdominal pressure remained comparable within and across conditions, whereas obliquus internus, obliquus externus and rectus abdominis activities either markedly increased (flexion) or decreased (extension). Trunk twisting movements showed reciprocal patterns of activity between the left and right sides of transversus abdominis, indicating an ability for torque development. During trunk flexion--extension, transversus abdominis showed less distinguished changes of activity possibly relating to a general stabilizing function. In varied pulsed Valsalva manoeuvres, changes in peak intra- abdominal pressure were correlated with mean amplitude electromyograms of all abdominal muscles, excluding rectus abdominis. It is concluded that the co-ordinative patterns shown between the muscles of the ventrolateral abdominal wall are task specific based upon demands of movement, torque and stabilization. It appears that transversus abdominis is the abdominal muscle whose activity is most consistently related to changes in intra-abdominal pressure.

Gastric Tonometry is an important tool being used more frequently in the Intensive Care Unit (ICU). Tonometry is used to collect normal saline which has equilibrated with the stomach contents and is used in combination with a sample of arterial blood to calculate intragastric PaCO2 and intramucosal pH (pHi). These values are indicative of gastric perfusion. Correct performance of each of the 5 procedural steps to instill and then collect the normal saline is paramount for accuracy of the CO2 and pHi results. The aim of this study was to examine how consistently nurses perform the procedure. Study participants comprised two groups of 15 registered nurses (RNs) chosen at random from the nurses employed in the ICU at Liverpool Hospital (NSW, Australia). The first group of RNs were asked to answer a questionnaire before and after performing the tonometry procedure under simulated conditions. The second group were asked to perform the tonometry procedure only. Each participant was observed by one of the researchers whilst performing all of the procedural steps. Regardless of critical care experience of participants or the number of years since registration a s a nurse, error rates in performing the specimen collection/procedure were as high as 34%. This study is designed to examine the previously unaddressed area of how accurately nursing staff follow systematic instructions to collect the mucosal sample.

Adverse effects of increased intra-abdominal pressure (IAP) on cardiac, pulmonary, and renal function have been well described. Abdominal wound healing complications seen in the massively injured patient may also be associated with IAP. The effects of IAP on abdominal wall blood flow, however, have not been documented. This study examines rectus sheath (RS) blood flow in a porcine model of increased IAP. Seven domestic swine were anesthetized with pentobarbital and maintained with isoflurane. Swan-Ganz and femoral arterial catheters were placed for measurement of mean arterial pressure (MAP), cardiac output (CO), and pulmonary capillary wedge pressure (PCWP). A midline incision was performed for placement of laser flow probe on the RS and for placement of catheters to raise and measure IAP. Intra-abdominal pressure was then increased by installation of lactated ringers (LRs) into the peritoneum. Mean arterial pressure was maintained throughout the procedure with intravenous LR. Hemodynamics and RS blood flow data were obtained at baseline, 10, 20, 30, and 40 mm Hg IAP. Analysis of data was done by paired t-test with level of significance at P less than 0.05 and linear regression. Rectus sheath blood flow was significantly reduced at all pressure levels when compared to baseline and negatively correlated (r = -0.82) with increasing IAP. Since indices of systemic perfusion were maintained with increasing IAP, the decreased RS blood flow is most likely due to increased compartmental pressure within the abdomen.

The effects of increased intra-abdominal pressure (IAP) on intestinal blood flow were studied in eight anesthetized pigs. Mesenteric artery blood flow (MABF), intestinal mucosal blood flow (IMBP), tonometric intramucosal pH (pHi), mean BP (MAP), cardiac output (CO), and pulmonary artery wedge pressure (PAWP) were measured as IAP was raised to 10, 20, 30, and 40 mm Hg by infusing lactated Ringer's solution (LR) into the peritoneal cavity. The MAP was kept constant with IV LR. Cardiac output fell slightly from 5.4 +/- 1.1 at baseline to 4.0 +/- 1.2 L/min at an IAP of 40 mm Hg (p less than 0.05). An IAP of 20 mm Hg caused significant decreases in MABF (73% +/- 22% of baseline) (p less than 0.05) and IMBF (61% + 12% of baseline) (p less than 0.05). These changes became progressively greater as the IAP was increased to 40 mm Hg. The pHi fell to 6.98 +/- 0.14 at 40 mm Hg IAP (p less than 0.01), indicating severe mucosal ischemia. Thus increased IAP can cause severe intestinal ischemia, which may be more important than the cardiac, pulmonary, and renal changes usually described.

The effects of increased intra-abdominal pressure (IAP) on hepatic perfusion were studied in five anesthetized pigs. Doppler flow probes were used to measure hepatic artery blood flow (HABF) and portal venous blood flow (PVBF), and laser Doppler flowmetry was used to assess changes in hepatic microvascular blood flow (HMVBF). Hepatic blood flow responses to 10, 20, 30 and 40 mm Hg increases in IAP were assessed while the mean arterial BP (MAP) was maintained at baseline levels with IV crystalloid infusions. Although cardiac output and MAP were normal, HABF and HMVBF fell significantly with 10 mm IAP, and at 20 mm Hg IAP, HABF was 45% of the control value, PVBF was 65% of the control value, and HMVBF was 71% of the control value (p less than 0.05). At 30 and 40 mm Hg, hepatic blood flow was reduced even more. Thus, modest increases in IAP can cause significant impairment of hepatic perfusion despite a normal BP and cardiac output.

Intra-abdominal hypertension is a lethal syndrome that can be treated. It is most often seen in critically ill surgical patients. The cornerstone of therapy is reduction of intra-abdominal pressure. Unfortunately, even with appropriate treatment, mortality is still high.

Four burned children suffering complications from elevated intra-abdominal pressures prompted initiation of a prospective study to determine the value of intra-abdominal pressure measurements in 30 children with large burns. Intra-abdominal pressures were measured every 4 hours during burn shock or sepsis, or daily during periods of stability. Patients were arbitrarily divided into those having one or more measurements > or = 30 mm Hg or all values < 30 mm Hg. Patients in the > or = 30 mm Hg group had significantly larger burns, higher mortality, and increased instances of sepsis. Five patients had elevated intra-abdominal pressures during burn shock, with two requiring abdominal escharotomies. Seven were at > 30 mm Hg during sepsis, with three requiring paralysis, and one each requiring placement of a peritoneal catheter or laparotomy. Significant intra-abdominal pressure elevations may occur in patients with extensive burns and are associated with a poorer prognosis. Elevation of intra-abdominal pressure should be considered in severely burned patients with oliguria, hypoventilation, or hypotension.

OBJECTIVE: To compare gastric mucosal pH (pHi) and global oxygen variables [Oxygen Delivery Index (DO2I) and Oxygen Consumption Index (VO2I)] as indicators of adequacy of resuscitation after major trauma. METHODS: Twenty-seven patients were prospectively randomized into two groups: group 1 (n = 11), normalization and maintenance of pHi at or above 7.30; and group 2 (n = 16), maintaining a DO2I of 600 and a VO2I of > 150. The groups had statistically similar injury severity scores, lactate, and base deficit. RESULTS: The goals of therapy were achieved within 24 hours of admission in 10 of the 11 patients in group 1 and in 15 of the 16 patients in group 2. One patient (9.1%) in group 1 died. This patient had transient stabilization of pHi to 7.3 and subsequently had persistent mucosal acidosis. Of the 10 patients with pHi > 7.3 at 24 hours, 9 survived. In group 2, 5 (31.3%) died. Four of the 5 nonsurvivors had achieved DO2I and VO2I goals, but had pHi < 7.3 at 24 hours. A comparison of time taken for optimization of DO2I, VO2I, lactate, base excess, and pHi showed pHi and lactate as the variables different in survivors and nonsurvivors. Six of the 8 patients who developed multiple organ dysfunction syndrome had pHi < 7.3 at 24 hours. Persistently low pHi was the first sign of bacteremia (3 patients), small bowel gangrene or pregangrene (2 patients), intestinal anastomotic leak (2 patients), intra-abdominal hypertension (4 patients), and intra-abdominal abscess (5 patients). It was the first finding in all the nonsurvivors at least 72 hours before death. CONCLUSIONS: pHi may be an important marker to assess the adequacy of resuscitation. pHi monitoring may provide early warning for systemic complications in the postresuscitation period.

BACKGROUND: Changes in intra-abdominal pressure (IAP) have significant circulatory effects. However, whether this may influence the gastroesophageal collateral blood flow in patients with cirrhosis has not been studied. METHODS: In 14 portal hypertensive cirrhotics, serial hemodynamic measurements were obtained in baseline conditions 30 minutes after the mechanical increase of IAP by 10 mm Hg and 30 minutes after returning IAP to baseline levels. RESULTS: Increasing IAP caused similar increases in free and wedged hepatic venous pressures (+10.3 mm Hg and +11.0 mm Hg, respectively; P < 0.005), without changing the hepatic venous pressure gradient (HVPG). However, there were significant decreases in cardiac output (-18%; P < 0.005) and hepatic blood flow (-20%; P < 0.05), whereas azygos blood flow, an index of gastroesophageal collateral blood flow, increased markedly (+23%; P < 0.005). The opposite occurred after releasing the high IAP. CONCLUSION: In portal hypertensive cirrhotics, acute changes in IAP did not change HVPG but markedly modified splanchnic and systemic hemodynamics. Brief elevations of IAP may have deletereous effects, as shown by the increase in azygos blood flow and the decrease in cardiac output and hepatic blood flow, whereas reduction of a high IAP causes the opposite changes and may be beneficial.

OBJECTIVES: To determine the effect of increased intra-abdominal pressure (IAP) on pulmonary compliance and to determine an effective means to measure IAP. DESIGN: A prospective study. SETTING: An urban tertiary care hospital. PATIENTS: Twenty-six adult patients undergoing laparoscopic cholecystectomy. INTERVENTIONS: Intra-operative management of laparoscopic cholecystectomy requiring endotracheal intubation with general anesthesia, nasogastric and urinary bladder catheters, and position changes. Additional interventions included use of a rectal manometer and a respiratory pressure module inserted within the ventilator circuit. MAIN OUTCOME MEASURES: Correlation of changes in IAP with changes in dynamic pulmonary compliance, measured as tidal volume/(end inspiratory pressure--end expiratory pressure) and comparison of three different measurement techniques (bladder, rectal, and gastric) with a standard technique (insufflation pressure) in three different positions (supine, Trendelenburg's, and reverse Trendelenburg's). RESULTS: Compliance was significantly related to insufflation pressure (P < .001) by analysis of variance. In the gas insufflation model, the mean increment in bladder pressure reflected most closely the IAP increment in the supine position (5.7 vs 6 mm Hg) but not in the Trendelenburg (2.1 vs 6 mm Hg) and reverse Trendelenburg positions (3.4 vs 6 mm Hg). Rectal and gastric pressures were also position dependent and technically less reliable. CONCLUSIONS: Increased IAP has a major influence on pulmonary compliance (50% decrease at 16 mm Hg). Measurements of IAP by intraorgan manometry are position dependent and may not accurately reflect the intraperitoneal pressure.

It has been suggested that an elevated intra-abdominal pressure (IAP) can impair renal function. In a prospective longitudinal study, the IAP of 42 patients admitted to an intensive care unit after abdominal aortic surgery was monitored. When compared with the other patients, the 22 patients (53%) who developed renal impairment had higher IAP (17.8 +/- 6.0 mmHg versus 14.1 +/- 4.8 mmHg; P less than 0.01) and APACHE II scores (15.6 +/- 6.0 versus 9.8 +/- 4.6; P less than 0.01). Each of the 10 patients who were re-explored because of haemodynamic instability and oliguria had an IAP of greater than 18 mmHg (positive predictive value = 85%, negative predictive value = 62%). Following re-exploration, the urinary output increased by 115 +/- 40 mL/h (P less than 0.01), and the IAP decreased by 10 +/- 3 mmHg (P less than 0.01). Although it is concluded that an IAP greater than 18 mmHg is a significant risk factor for the development of impaired renal function, it was not possible to prove a causal relationship between these events. Nevertheless, such a relationship has been demonstrated in animal and human models.

An intraabdominal compartment-syndrome developed due to ischemia and hemorrhage through a suture subsequent to partial reconstruction of the abdominal aorta, aorto-mesenterical and bilateral aorto-renal T-bypass. In order to decrease the elevated intraabdominal pressure, a decompression with secondary wound closure by an artificial net is the therapy of choice. The arising problems which determined the fatal outcome of this case are discussed.

The cardiopulmonary effects of acutely elevated intra-abdominal pressure (IAP) were studied in a porcine model to help define more clearly IAP effects in patients with trauma. IAP was increased in six anesthetized swine by intra-abdominal instillation of isotonic ethylene glycol up to an IAP of 25 mm Hg above baseline. Systemic and pulmonary hemodynamic parameters were measured, as well as the effects on bladder pressure, pleural pressure, and pulmonary function. At IAP of 25 mm Hg above baseline, intravascular volume expansion with saline was administered to return the cardiac index (CI) to baseline. Raising IAP correlated with measured bladder pressures (r = 0.9, p = 0.001). At IAP of 25 mm Hg, CI was significantly decreased (p < 0.05, analysis of variance (ANOVA); 3.6 +/- 0.3 vs. 2.2 +/- 0.3 L/min/m2); whereas wedge, pulmonary arterial, and pleural pressures were all elevated (p < 0.05, ANOVA). However, transarterial wedge pressure (wedge--pleural pressure) declined nonsignificantly with increasing IAP. Raised IAP caused impaired pulmonary function with a decreased (p < 0.05, ANOVA) PaO2 and increased (p < 0.05, ANOVA) PaCO2. Despite the elevated wedge pressure, fluid resuscitation returned CI to baseline. These data clarify the hemodynamic changes associated with raised IAP and indicate that care must be taken in interpreting hemodynamic measurements to determine intravascular fluid status in patients with elevated IAP.

The value of postoperative monitoring of intra-abdominal pressure (IAP) in surgical patients has not been established. This study prospectively evaluated the occurrence of increased IAP and its association with renal impairment and outcome in surgical patients admitted to an intensive care unit. One hundred consecutive patients after laparotomy were studied, 88 of whom had complete IAP measurements. IAP was measured using an intravesical catheter and was considered increased when equal to 20 mmHg or above. Renal impairment was defined as a postoperative serum creatinine concentration of greater than 130 mumol/l, or an increase in serum creatinine of greater than 100 mumol/l within 72 h of surgery. The median (range) APACHE (Acute Physiology And Chronic Health Evaluation) II score of the patients was 13.5 (4-43). The incidence of raised IAP was 29 of 88 (33 per cent). Renal impairment was present in 29 of 88 (33 per cent), of whom 20 of 29 (69 per cent) had raised IAP (P < 0.01). The odds ratios (95 per cent confidence interval) for the development of renal impairment and death in patients with increased IAP were 12.4 (3.8-41.7) and 11.2 (2.8-47.9) respectively. There is a clinically significant association between increased IAP and renal impairment in patients admitted to an intensive care unit after laparotomy.

OBJECTIVE: This study assessed the accuracy of an intragastric method of measuring intra-abdominal pressure (IAP). DESIGN: Prospective sequential study with simultaneous paired measurement of gastric and urinary bladder pressures. SETTING: Operating theatre, University Teaching Hospital. PATIENTS: 9 patients undergoing laparoscopic cholecystectomy were studied. INTERVENTIONS: Intraperitoneal pressures were monitored during peritoneal insufflation at laparoscopy up to a pressure of 20 mmHg. MEASUREMENTS AND RESULTS: Intra-abdominal pressure measurements were recorded simultaneously using a gastric balloon and urinary catheter. Gastric pressure may be up to 4 mmHg higher or 3 mmHg lower than urinary bladder pressure. CONCLUSIONS: Intra-abdominal pressure can be measured easily in this new fashion, allowing a continuous pressure trend to be obtained without interfering with urinary output estimation.