Increase In Increased Intra-abdominal Pressure Research Articles

Sublingual microcirculatory changes during transient intra-abdominal hypertension – A prospective observational study in laparoscopic surgery patients

Microvascular alterations and intra-abdominal hypertension are both involved in development of organ failure. It is not known whether increased intra-abdominal pressure (IAP) is associated with microcirculatory perfusion derangements. Transient increase in IAP induced by pneumoperitoneum affects sublingual microcirculation. 16 laparoscopic cholecystectomy patients were studied. Sidestream dark field (SDF) imaging was used to evaluate sublingual microcirculation. Microcirculatory videos were done before surgery, at least 15 minutes after initiation of pneumoperitoneum and 1 hour after the pneumoperitoneum. Microcirculation cut-off value for vessels was 20 μm. IAP was held at 12.6 (from 12 to 14) mmHg, mean (SD) duration of pneumoperitoneum was 41 (14) minutes. At the baseline, mean total vascular density was 18.8 (2.6) and perfused vessel density 13.2 (2.9) per mm². Proportion of perfused vessels was 59 (11) % and microvascular flow index 2.2 (0.4). Median (IQR) heterogeneity index was 0.6 (0.4-0.9) and mean De Backer score 13.6 (1.5). Increase in IAP did not cause significant changes in sublingual microcirculatory parameters. Transiently increased IAP due to pneumoperitoneum does not affect sublingual microcirculatory blood flow and vessel density in patients undergoing laparoscopic surgery. However, the low proportion of perfused vessels indicates the prevalence of perioperative microcirculatory deficiency in these patients.

Plateau and Transpulmonary Pressure With Elevated Intra-Abdominal Pressure or Atelectasis

ARDSnet standards limit plateau pressure (Pplat) to reduce ventilator induced lung injury (VILI). Transpulmonary pressure (Ptp) [Pplat-pleural pressure (Ppl)], not Pplat, is the distending pressure of the lung. Lung distention can be affected by increased intra-abdominal pressure (IAP) and atelectasis. We hypothesized that the changes in distention caused by increases in IAP and atelectasis would be reflected by Ptp but independent of Pplat. In Yorkshire pigs, esophageal pressure (Pes) was measured with a balloon catheter as a surrogate for Ppl under two experimental conditions: (1) high IAP group (n=5), where IAP was elevated by CO2 insufflation in 5 mm Hg steps from 0 to 30 mm Hg; and (2) Atelectasis group (n=5), where a double lumen endotracheal tube allowed clamping and degassing of either lung by O2 absorption. Lung collapse was estimated by increases in pulmonary shunt fraction. High IAP: Sequential increments in IAP caused a linear increase in Pplat (r2=0.754, P<0.0001). Ptp did not increase (r2=0.014, P=0.404) with IAP due to the concomitant increase in Pes (r2=0.726, P<0.0001). Partial Lung Collapse: There was no significant difference in Pplat between the atelectatic (21.83+/-0.63 cm H2O) and inflated lung (22.06+/-0.61 cmH2O, P<0.05). Partial lung collapse caused a significant decrease in Pes (11.32+/-1.11 mm Hg) compared with inflation (15.89+/-0.72 mm Hg, P<0.05) resulting in a significant increase in Ptp (inflated=5.97+/-0.72 mm Hg; collapsed=10.55+/-1.53 mm Hg, P<0.05). Use of Pplat to set ventilation may under-ventilate patients with intra-abdominal hypertension and over-distend the lungs of patients with atelectasis. Thus, Ptp must be used to accurately set mechanical ventilation in the critically ill.

Impact of pneumoperitoneum on renal perfusion and excretory function: beneficial effects of nitroglycerine

Increased intra-abdominal pressure (IAP) (pneumoperitoneum) during laparoscopic surgery may result in adverse effects on kidney function. The mechanisms underlying this phenomenon have not been fully determined. The present study was designed to: (1) investigate the effects of incremental increases in IAP on renal function in normal rats and (2) evaluate whether the nitric oxide (NO) system is involved in renal dysfunction characterizing pneumoperitoneum. Male rats were organized into two groups. The first group was subjected to IAP of 0 (baseline), 7 or 14 mmHg, over 1 h for each pressure, followed by a deflation period of 60 min (recovery). Two additional groups were pretreated with: (1) non-depressor dose of nitroglycerine (NTG) and (2) nitro-L-arginine-methylester (L-NAME), an NO synthase inhibitor, before applying 14 mmHg for 1 h. Urine flow rate (V), Na+ excretion (U(Na)V), glomerular filtration rate (GFR), renal plasma flow (RPF), and blood pressure were determined throughout the experiments. There were no significant changes in V, U(Na)V, GFR, and RPF during 7 mmHg insufflation. However, significant reductions in these parameters were observed during 14 mmHg: V from 8.49 +/- 0.92 to 6.12 +/- 0.54 microl/min, U(Na)V from 1.29 +/- 0.28 to 0.39 +/- 0.09 microEq/min, and FE(Na) from 0.37 +/- 0.11 to 0.27 +/- 0.04%. These alterations in excretory functions were associated with a considerable decline in GFR from 1.85 +/- 0.09 to 0.88 +/- 0.09 ml/min, p < 0.05, (-46.3 +/- 5.2% from baseline) and RPF from 8.66 +/- 0.62 to 4.33 +/- 0.49 ml/min, p < 0.05, (-51.93 +/- 5.24% from baseline), without a significant change in mean arterial blood pressure (MAP). When the animals were pretreated with NTG, the adverse effects of pneumoperitoneum on V, U(Na)V, GFR, and RPF were substantially improved, suggesting that NO system plays a beneficial counter-regulatory role during laparoscopy. In line with this notion, pretreatment with L-NAME remarkably aggravated pneumoperitoneum-induced renal hypoperfusion and dysfunction. Decreased renal perfusion and function are induced by IAP pressure of 14 mmHg. These adverse effects are probably related to interference with the NO system, and could be partially ameliorated by pretreatment with NTG.

Prone position in mechanically ventilated patients – the hard or the soft way?

Prone positioning may even in patients without abdominal hypertension result in an increased intra-abdominal pressure (IAP). Previous research could not demonstrate a marked increase in IAP associated with cardiovascular, renal, or hepato-splanchnic dysfunction when patients were proned in air-cushioned beds. Michelet and colleagues in this issue of Critical Care report that the increase in IAP in the prone position depends on the used mattress type. Compared with air-cushion beds, conventional foam mattresses resulted in a greater increase in IAP which was associated with a decrease in the plasma diappearance rate of indocyanin green (PDRICG) indicating inadequate heptosplanchnic function.

Systemic consequences of ileus

Ileus refers to the partial or complete blockage of the small and/or large intestine either by functional (adynamic or paralytic ileus) or mechanical bowel obstruction. The diffuse gastrointestinal dysmotility during functional and mechanical ileus may result in intestinal dilatation, increased luminal pressure and gut wall ischaemia which may lead to increased intra-abdominal pressure (IAP). Any type of ileus may promote abdominal fluid sequestration with severe systemic hypovolaemia, intestinal bacterial overgrowth with the evolution of bacterial translocation and systemic invasive infections and inflammation of the intestinal wall with concomitant release of cytokines and the development of the systemic inflammatory response syndrome. The most serious complications of ileus are mediated by an increase in IAP. Intra-abdominal hypertension has been found in up to 20% of critically ill patients and may lead to a broad pattern of systemic consequences with multiple organ dysfunction, including cardiovascular, hepatic, pulmonary, renal and neurological function. The abdominal compartment syndrome is an emergency condition which is defined as elevation of IAP above 20 to 25 mmHg and the presence of systemic consequences. Therapeutic considerations include the maintenance of adequate hydration status, avoidance of drugs known to impair intestinal perfusion, stimulation of gastric and intestinal motility and various nutritional aspects. Colonic tube placement after decompressive colonoscopy may be effective in reducing intestinal dilatation. In the abdominal compartment syndrome the ‘open abdominal approach’ with decompressive laparotomy by opening the peritoneal cavity and temporary abdominal closure is the therapy of choice.

Increased intra-abdominal pressure results in both obstructive and nonobstructive types of impairments of renal pelvic excretion.

An experimental study has been conducted to evaluate the effects of increased intra-abdominal pressure (IAP) on the excretion function from renal pelvis into the ureter. Sixteen adult male New Zealand rabbits were randomly allocated in two groups after obtaining basal scintigraphies. Group I consisted of 8 rabbits which were subjected to an increased IAP for ten day period. In Group II an other 8 rabbits were subjected to an increased IAP for 60 day period. At the end of the periods of increased IAP the post-pressure scintigraphic evaluations of both groups were carried out. Time to maximum activity (Tmax), T1/2 and T2/3 values of the radiopharmaceutical in the kidneys and down slope parameters (DS1/2, DS2/3) were calculated from the renogram curves of both right and left kidneys. Comparison of basal and post-pressure scintigrapies and the mean difference of the renogram parameters between groups were performed. All basal scintigraphies were normal. Post-pressure scintigraphies revealed an obvious delay in the excretion phase in both groups. Both kidneys of a rabbit in group I revealed a non-obstructive pattern through responding well to administration of diuretic. Furthermore both kidneys of a rabbit from group II have revealed an obstructive pattern. T1/2 and T2/3 values were significantly elevated and mean DS1/2, DS2/3 were significantly decreased in post-pressure scintigraphies of the both groups without revealing a statistically significant difference between groups I and II. The mean difference of Tmax was significantly increased in group II. The increases in IAP, through the compressive effect upon ureters together with a concomitant increase in intravesical pressure, may impair the passage of urine from renal pelvis into ureter. The impaired passage may play a role in the development of hydronephrosis which may either reveal a nonobstructive and/or obstructive pattern.

Anesthetic Considerations for Bariatric Surgery

According to the National Institutes of Health, obesity is a major health problem with clearly established health implications, including an increased risk for coronary artery disease, hypertension, dyslipidemia, diabetes mellitus, gallbladder disease, degenerative joint disease, obstructive sleep apnea, and socioeconomic and psychosocial impairment (1). The risk of developing one or more of these obesityrelated conditions is based on body mass index (BMI), with 25–30 kg/m 2 being low risk and 40 kg/m 2 being very high risk (2). The prevalence of obesity in the 18- to 29-yr-old group increased from 12% in 1991 to 18.9% in 1999 (3). Bariatric surgery encompasses a variety of surgical weight loss procedures used to treat morbid obesity. Obesity is clinically expressed in terms of BMI or Quetelet’s index (4), which is derived by dividing weight by the square of height to estimate the degree of obesity. Thus, BMI body weight (kg)/height 2 (m 2 ). Morbid obesity is a BMI more than 35 kg/m 2 , and super morbid obesity is BMI more than 55 kg/m 2 . The indications for surgical treatment of severe obesity, as outlined in the 1991 National Institutes of Health Consensus Development Conference Panel, include an absolute BMI more than 40 kg/m 2 or BMI more than 35 kg/m 2 in combination with lifethreatening cardiopulmonary problems or severe diabetes mellitus (1). Patients seeking surgical weight loss must have proven attempts at medically supervised weight loss. Documentation of loss of 5% to 10% excess body weight or weight gain after at least 6 mo of diet modification, exercise, and medical therapy or nonimprovement in comorbid conditions during this period indicates failure. Studies have shown that weight loss of 5%–10% of initial body weight improves glucose intolerance and Type II diabetes, hypertension, and dyslipidemia (5–7). The average expenditure is approximately $7000 per year per patient on weight loss programs and equipment. Unfortunately, long-term weight loss is the exception, and most patients regain weight, sometimes more than they initially lost.

Measuring intra-abdominal pressure in the intensive care setting

Increased intra-abdominal pressure (IAP) may occur in critically ill patients. The easiest method to estimate IAP at the bedside is the bladder pressure measurement. A standard procedure (same volume infused, pressure transducers, and patient‘s position) should be used to obtain comparable and reproducible data among different patients and during different stages and time of the disease. The increase in IAP leads to two major pathological conditions: 1) the intraabdominal hypertension (IAP above 16 cmH2O) and 2) the abdominal compartment syndrome (IAP above 30 cmH2O). Increased IAP negatively affects pulmonary, cardiovascular, renal, gastrointestinal and central nervous system function. Most of critically ill patients have an intraabdominal hypertension, while few of them (less than 5%) present clinical characteristics of abdominal compartment syndrome. IAP is different among different categories of patients. The highest mean values during intensive care unit stay have been reported in respiratory and cardiologic patients among medical categories and in neurologic patients among surgical patients. IAP seems to be correlated with severity scores but its relation to mortality is uncertain. Routine measurements of IAP by means of bladder pressure are not associated with an increased rate of urinary tract infections. Future trials are warranted to better evaluate the role of routine IAP measurements on clinical management of critically ill patients.

Changes in bladder of rabbits subjected to elevation of intraabdominal pressures

Background/Purpose: An experimental study has been conducted to evaluate the effects of increased intraabdominal pressure (IAP) on the morphology of the bladder of rabbits. Methods: Experiments were performed on 20 adult male New Zealand rabbits. Six rabbits served as the control group (group I). Seven rabbits were subjected to increased IAP of 7 cm H2O for 10 days through installing air into the abdominal cavity (group II). Increased IAP was maintained for 60 days in another group of 7 rabbits (group III). Bladders were removed and fixed in 10% formalin for routine process. Paraffin sections of 5 to 7 μm were stained with H & E for light microscopic evaluation. Histopathologic parameters were scored, and the mean scores according to groups were compared by 1-way analysis of variance (ANOVA). The mean values of groups were compared separately by Tukey-Kramer multiple comparison test. In these tests, P value less than.05 was considered statistically significant. Results: All of the bladder strips obtained from animals subjected to 10 days of pressure increase (group II) showed mild to severe degree of vacuolation and desquamation of urothelium. Both vacuolation and desquamation of urothelium were present in all of the strips obtained from rabbits with 60 days pressure increase (group III). Additionally, there were infiltration and congestion of the urothelium together with vacuolation, suburothelial edema, and desquamation in 4 group III rabbits. Moderate or severe congestion in the lamina propria was present in bladder strips of group II rabbits. The congestion of the lamina propria was advanced, and additional moderate to severe inflammation was present in 4 rabbits of group III. Mean histopathologic scores of urothelium (P <.00001) and lamina propria (P =.002) differed significantly among groups. When the groups were compared one by one, the differences between the group I and group II and group II and III were significant (P <.05). Although seroza appeared normal in both group I and II, moderate congestion and infiltration of the seroza was present in the bladder strips of group III (P <.05). Conclusion: Increases in IAP for even 10 days show damaging effects on the bladder. Extended period resulted in augmentation of the damage. J Pediatr Surg 36:995-999. Copyright © 2001 by W.B. Saunders Company.

Chronically increased intra-abdominal pressure produces systemic hypertension in dogs.

Determine if increased intra-abdominal pressure (IAP) alone can cause systemic hypertension in a chronic canine model. Evaluate effects of increase in IAP with progressive inflation and deflation of an intra-abdominal balloon on systemic blood pressure in experimental and control animals. Male dogs weighing 15-25 kg underwent placement of an intra-abdominal balloon which was progressively inflated on a weekly basis in the experimental animals (5) over 4 weeks to 25 mmHg above baseline and kept there for an additional 2 weeks before gradual deflation over 2 weeks. Control animals (5) had the balloon placed but not inflated. Pain was controlled with osmotic analgesic pumps. The animals were anesthetized, blood pressure (BP) measured and blood drawn for plasma renin activity (PRA), aldosterone, atrial naturetic peptide (ANP), catecholamines, and serum sodium (Na). A right heart catheter was inserted for measuring cardiac output (CO) and pulmonary artery occlusion pressure (PAOP) at baseline, week 5 (maximal IAP) and week 7 (after balloon deflation). The animals were weighed and urinary bladder pressures recorded weekly before and after abdominal balloon inflation. Systolic (122+/-3 to 155+/-5 mmHg, P<0.05) and diastolic (82+/-4 mmHg to 107+/-7 mmHg, P<0.05) BP rose at 5 weeks at 25 mmHg IAP>baseline and returned to control with balloon deflation. Both systolic and diastolic BP rose (P<0.05) above control animals BP at 15 mmHg IAP at 2 weeks and remained elevated until abdominal decompression, at week 7. There were no significant changes in net animal weight, PRA, aldosterone, ANF, catecholamines, Na, CO or PAOP. Increased IAP from progressively inflating an intra-abdominal balloon in dogs was associated with significant increases in systolic and diastolic BP that resolved with balloon deflation. Increased IAP may be a cause for systemic hypertension in central obesity and pre-eclampsia.

Compliance curves during peritoneal dialysate infusion are like a distensible tube and are similar at multiple UGI sites.

Disorders from increased intraabdominal pressure (IAP) result from filling the abdominal cavity beyond its capacity. The aims of this study were 1) to examine pressure:volume curves as fluid is infused into the intraabdominal cavity, and 2) to ascertain the best UGI site for indirect IAP measurements. Chronic ambulatory peritoneal dialysis patients were studied (n = 4) supine. On day 1, manometry catheters measured IAP indirectly (intragastric and intrarectal) and intraesophageal (three sites) pressure. On day 2, antral-duodenal-jejunal manometry was performed to compare indirectly measured IAP at multiple sites. On both days, dialysate was infused at 200 ml/min until IAP was > or = 15 mm Hg or patient experienced severe discomfort. Filling had three phases: 1) an initial small increase in IAP as infusion began; 2) minimal further increase in IAP during infusion to about 3 L concurrent with a progressive increase in abdominal girth and mild abdominal discomfort; and 3) a linear increase in IAP with infusion > 3 L concurrent with intense abdominal discomfort and little increase in abdominal girth. During study day 2, intragastric, intraduodenal, and intrajejunal pressures were usually similar. The compliance curve of the abdomen with filling is similar to that of the bladder and large veins. Compliance curves with provocative meals may be useful in evaluating postprandial abdominal pain, dyspepsia, and bloating.

Compliance curves during peritoneal dialysate infusion are like a distensible tube and are similar at multiple UGI sites

OBJECTIVE: Disorders from increased intraabdominal pressure (IAP) result from filling the abdominal cavity beyond its capacity. The aims of this study were 1) to examine pressure:volume curves as fluid is infused into the intraabdominal cavity, and 2) to ascertain the best UGI site for indirect IAP measurements. METHODS: Chronic ambulatory peritoneal dialysis patients were studied (n = 4) supine. On day 1, manometry catheters measured IAP indirectly (intragastric and intrarectal) and intraesophageal (three sites) pressure. On day 2, antral-duodenal-jejunal manometry was performed to compare indirectly measured IAP at multiple sites. On both days, dialysate was infused at 200 ml/min until IAP was ≥15 mm Hg or patient experienced severe discomfort. RESULTS: Filling had three phases: 1) an initial small increase in IAP as infusion began; 2) minimal further increase in IAP during infusion to about 3 L concurrent with a progressive increase in abdominal girth and mild abdominal discomfort; and 3) a linear increase in IAP with infusion >3 L concurrent with intense abdominal discomfort and little increase in abdominal girth. During study day 2, intragastric, intraduodenal, and intrajejunal pressures were usually similar. CONCLUSIONS: The compliance curve of the abdomen with filling is similar to that of the bladder and large veins. Compliance curves with provocative meals may be useful in evaluating postprandial abdominal pain, dyspepsia, and bloating.

Hemorrhage Exacerbates Bacterial Translocation at Low Levels of Intra-abdominal Pressure

It has been shown previously that the adverse cardiopulmonary sequelae of increased intra-abdominal pressure (IAP) are worsened by hemorrhage and resuscitation. Bacterial translocation (BT) to the mesenteric lymph nodes (MLNs), liver, and spleen has also been shown to occur with increased IAP. To investigate the hypothesis that BT associated with elevated IAP would be significantly increased after hemorrhage and resuscitation. Anesthetized adult male rats had femoral artery and vein catheters placed, and an intra-abdominal catheter placed to measure IAP. Group 1 underwent surgery only and served as controls. Group 2 had IAP raised to 10 mm Hg by infused lactated Ringer's solution for 40 minutes. Group 3 had a 25% hemorrhage, followed by resuscitation by infused lactated Ringer's solution and shed blood. Group 4 first had a 25% hemorrhage, resuscitated using infused lactated Ringer's solution and shed blood, and then had IAP raised to 10 mm Hg by infused lactated Ringer's solution for 40 minutes. All groups were killed after 2 hours, and had MLNs, liver, and spleen harvested for quantitative cultures. Hemorrhage and resuscitation alone did not increase BT to the MLNs, liver, or spleen. An increase in IAP to 10 mm Hg resulted in a significant level of BT to the MLNs and liver on MacConkey II agar (P<.05), and a significant increase in the level of BT only to the liver on trypticase soy agar with 5% sheep's blood (P<.05). Hemorrhage and resuscitation did increase the level of BT to the liver and spleen when IAP was increased to 10 mm Hg (P<.05). In this model, hemorrhage and resuscitation alone did not increase BT to the MLNs, liver, or spleen. However, hemorrhage and resuscitation increased BT to the liver and spleen when IAP was increased to 10 mm Hg. This supports the concept that prior hemorrhage and resuscitation exacerbates the effects of increased IAP.

Hemodynamic and respiratory effects of pneumoperitoneum and PEEP during laparoscopic pelvic lymphadenectomy in dogs.

Extended laparoscopic operations are being performed increasingly in high-risk patients. To assess the effects of increased intraabdominal pressure (IAP) and positive end-expiratory pressure (PEEP) on the hemodynamic and respiratory system during extended procedures a carbon dioxide pneumoperitoneum was artificially induced in 10 dogs undergoing laparoscopic pelvic lymphadenectomy. An increase in IAP up to 15 mmHg had no negative effect on the cardiovascular system. However, the combination of an increased IAP (10-15 mmHg) with PEEP (8 cmH2O) markedly depressed the hemodynamic variables. Measurement of arterial carbon dioxide and fractional end-tidal carbon dioxide revealed significant CO2 retention. We conclude from the results that laparoscopic pelvic lymphadenectomy should be performed in high-risk patients only under general anesthesia with expanded cardiopulmonary monitoring.

Effect of increased intra-abdominal pressure on hepatic arterial, portal venous, and hepatic microcirculatory blood flow.

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.

The effect of an abdominal belt on trunk muscle activity and intra-abdominal pressure during squat lifts

The purpose of this study was to determine whether abdominal belts such as those prescribed to industrial workers reduced trunk muscle activity and/or increased intra-abdominal pressure (IAP). In this study, six subjects lifted loads (72.7 to 90.9 kg) both with and without wearing a weightlifter belt. In addition, further trial conditions required that subjects lifted both with the breath held or continuously expiring on lifting effort. Dynamic hand loads were recorded together with intra-abdominal pressure (IAP) and abdominal, intercostal and low back EMG. Every subject demonstrated an increase in IAP when wearing the belt during both breathing conditions: 99 mmHg with no belt; 120 mmHg wearing belt (p less than 0.0001). However, it was also found that significant increases in IAP occurred (p less than 0.017) when the breath was held versus exhaling with or without the belt. One would expect that if the belt relieved either the direct compressive load on the spine or assisted IAP to produce an extensor moment then this would be reflected in diminished extensor muscle activity. Erector spinae activity tended to be lower with the breath held suggesting a reduced load on the lumbar spine although wearing a belt did not augment this reduction. In the case studies with subjects wearing an ergogenic corset designed for use by industrial manual materials handlers, perceptions of improved trunk stability were reported. However, the muscle activity and IAP results of this study during short duration lifting tasks make it difficult to justify the prescription of abdominal belts to workers.