Intra-abdominal hypertension in the critically ill: it is time to pay attention

Hypertonic saline solution drives neutrophil from bystander organ to infectious site in polymicrobial sepsis: a cecal ligation and puncture model

The effects of hypertonic saline solution (HSS) have been shown in several animal models of ischemia and shock. Literature has shown potential benefits of HSS modulating inflammatory response after sepsis in an animal model. We studied the HSS effects in sepsis through cecal ligation and puncture (CLP) in Balb-C mice. Groups studied: 1- CLP without treatment (CLP-C); 2- CLP treated with normal saline solution NaCl 0.9% – 34 ml/Kg (CLP-S); 3- CLP treated with HSS NaCl 7.5% – 4 ml/Kg (CLP-H); and 4- group (Basal) without no CLP or treatment. Volume infusion was always applied 30 min after CLP. Lung and peritoneal lavage were harvested after 6h and 24h of CLP to analyze cytokines amount, oxide nitric, lipid peroxidation and neutrophil infiltration. Neutrophil infiltration, ICAM-1, CXCR-2, and CXCL-1 in lung were reduced by HSS (CLP-H) compared to CLP-C or CLP-S. Neutrophil in peritoneal lavage was increased in 24h with HSS (CLP-H) compared to CLP and CLP-S. Peritoneal CXCR-2 was increased in CLP-C and CLP-S but presented a lower increase with HSS (CLP-H) after 6 hours. GRK-2 presented difference among the groups at 24 h, showing a profile similar to neutrophil infiltration. Pro-inflammatory cytokines (TNF-α and IL-6) were reduced by HSS treatment; CLP-S increased TNF-α. IL-10 was increased in lung tissue by the HSS treatment. The oxidative stress (TBARS and nitric oxide biochemistry markers) was reduced with HSS. Animal survival was 33.3% in CLP-C group, 46.6% in CLP-S group and 60% in the CLP-H group after the sixth day. The HSS protects the animal against sepsis. Our results suggest that the volume replacement modulate pro and anti-inflammatory mediators of an inflammatory response, but HSS presented a more effective and potent effect.

Abdominal catastrophes in the intensive care unit setting

Patients in the setting of the intensive care unit can develop intra-abdominal complications that may worsen outcome. Clinical suspicion of such complications coupled with early diagnosis and treatment may reduce morbidity and mortality associated with these processes. This article addresses the diagnosis and management of some of the common causes of intra-abdominal catastrophes.

Intra-abdominal hypertension in cardiac surgery

OBJECTIVES

The occurrence of intra-abdominal hypertension (IAH), as well as its promoting factors in cardiac surgery, has been poorly explored. The aim of the present study was to characterize intra-abdominal pressure (IAP) variations in patients undergoing cardiac surgical procedures, and to identify the risk factors for IAH in this setting.

METHODS

All consecutive adult patients requiring postoperative intensive care unit admission for >24 h were enrolled. Demographic data, pre-existing comorbidities, type and duration of surgery, cardiopulmonary bypass (CPB) use and duration, perioperative IAP, organ function and fluid balance were recorded. IAH was defined as a sustained increase in IAP >12 mmHg. Multivariate logistic regression and stepwise analyses identified the baseline and perioperative variables associated with IAH.

RESULTS

Of 69 patients, 22 (31.8%) developed IAH. In the logistic model, baseline IAP, high central venous pressure, vasoactive drugs administration, positive fluid balance, AKI, CPB, total sequential organ failure assessment score and age were all promoting factors for IAH (Hosmer-Lemeshow χ(2) = 7.23; P = 0.843). Baseline IAP, high central venous pressure and positive fluid balance were independent risk factors for IAH in the stepwise analysis. The ROC curve analysis, obtained by plotting the occurrence of IAH vs the IAP baseline value, showed an AUC of 0.75 (SE 0.064; 99% CI 0.62-0.87; P < 0.0001). The best IAP cut-off value was at 8 mmHg (sensitivity 63% and specificity 76%). Considering on- and off-pump surgery groups, fluid balance and vasoactive drugs use were significantly higher in the on-pump group. Linear regression analysis showed a positive correlation (P = 0.0001) between IAP changes and fluid balance only in the on-pump group.

CONCLUSIONS

IAH develops in one-third of cardiac surgery patients and is strongly associated with higher baseline IAP values, higher central venous pressure, positive fluid balance, extracorporeal circulation, use of vasoactive drugs and AKI. Determinants of IAH should be accurately assessed before and after surgery, and patients presenting risk factors must be monitored properly during the perioperative period. In this context, the baseline value of IAP may be a valuable and early warning parameter for IAH occurrence.

Surviving sepsis campaign: international guidelines for management of severe sepsis and septic shock: 2012

OBJECTIVE

To provide an update to the "Surviving Sepsis Campaign Guidelines for Management of Severe Sepsis and Septic Shock," last published in 2008.

DESIGN

A consensus committee of 68 international experts representing 30 international organizations was convened. Nominal groups were assembled at key international meetings (for those committee members attending the conference). A formal conflict of interest policy was developed at the onset of the process and enforced throughout. The entire guidelines process was conducted independent of any industry funding. A stand-alone meeting was held for all subgroup heads, co- and vice-chairs, and selected individuals. Teleconferences and electronic-based discussion among subgroups and among the entire committee served as an integral part of the development.

METHODS

The authors were advised to follow the principles of the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system to guide assessment of quality of evidence from high (A) to very low (D) and to determine the strength of recommendations as strong (1) or weak (2). The potential drawbacks of making strong recommendations in the presence of low-quality evidence were emphasized. Some recommendations were ungraded (UG). Recommendations were classified into three groups: 1) those directly targeting severe sepsis; 2) those targeting general care of the critically ill patient and considered high priority in severe sepsis; and 3) pediatric considerations.

RESULTS

Key recommendations and suggestions, listed by category, include: early quantitative resuscitation of the septic patient during the first 6 hrs after recognition (1C); blood cultures before antibiotic therapy (1C); imaging studies performed promptly to confirm a potential source of infection (UG); administration of broad-spectrum antimicrobials therapy within 1 hr of recognition of septic shock (1B) and severe sepsis without septic shock (1C) as the goal of therapy; reassessment of antimicrobial therapy daily for de-escalation, when appropriate (1B); infection source control with attention to the balance of risks and benefits of the chosen method within 12 hrs of diagnosis (1C); initial fluid resuscitation with crystalloid (1B) and consideration of the addition of albumin in patients who continue to require substantial amounts of crystalloid to maintain adequate mean arterial pressure (2C) and the avoidance of hetastarch formulations (1C); initial fluid challenge in patients with sepsis-induced tissue hypoperfusion and suspicion of hypovolemia to achieve a minimum of 30 mL/kg of crystalloids (more rapid administration and greater amounts of fluid may be needed in some patients) (1C); fluid challenge technique continued as long as hemodynamic improvement, as based on either dynamic or static variables (UG); norepinephrine as the first-choice vasopressor to maintain mean arterial pressure ≥ 65 mm Hg (1B); epinephrine when an additional agent is needed to maintain adequate blood pressure (2B); vasopressin (0.03 U/min) can be added to norepinephrine to either raise mean arterial pressure to target or to decrease norepinephrine dose but should not be used as the initial vasopressor (UG); dopamine is not recommended except in highly selected circumstances (2C); dobutamine infusion administered or added to vasopressor in the presence of a) myocardial dysfunction as suggested by elevated cardiac filling pressures and low cardiac output, or b) ongoing signs of hypoperfusion despite achieving adequate intravascular volume and adequate mean arterial pressure (1C); avoiding use of intravenous hydrocortisone in adult septic shock patients if adequate fluid resuscitation and vasopressor therapy are able to restore hemodynamic stability (2C); hemoglobin target of 7-9 g/dL in the absence of tissue hypoperfusion, ischemic coronary artery disease, or acute hemorrhage (1B); low tidal volume (1A) and limitation of inspiratory plateau pressure (1B) for acute respiratory distress syndrome (ARDS); application of at least a minimal amount of positive end-expiratory pressure (PEEP) in ARDS (1B); higher rather than lower level of PEEP for patients with sepsis-induced moderate or severe ARDS (2C); recruitment maneuvers in sepsis patients with severe refractory hypoxemia due to ARDS (2C); prone positioning in sepsis-induced ARDS patients with a PaO2/FIO2 ratio of ≤ 100 mm Hg in facilities that have experience with such practices (2C); head-of-bed elevation in mechanically ventilated patients unless contraindicated (1B); a conservative fluid strategy for patients with established ARDS who do not have evidence of tissue hypoperfusion (1C); protocols for weaning and sedation (1A); minimizing use of either intermittent bolus sedation or continuous infusion sedation targeting specific titration endpoints (1B); avoidance of neuromuscular blockers if possible in the septic patient without ARDS (1C); a short course of neuromuscular blocker (no longer than 48 hrs) for patients with early ARDS and a Pao2/Fio2 < 150 mm Hg (2C); a protocolized approach to blood glucose management commencing insulin dosing when two consecutive blood glucose levels are > 180 mg/dL, targeting an upper blood glucose ≤ 180 mg/dL (1A); equivalency of continuous veno-venous hemofiltration or intermittent hemodialysis (2B); prophylaxis for deep vein thrombosis (1B); use of stress ulcer prophylaxis to prevent upper gastrointestinal bleeding in patients with bleeding risk factors (1B); oral or enteral (if necessary) feedings, as tolerated, rather than either complete fasting or provision of only intravenous glucose within the first 48 hrs after a diagnosis of severe sepsis/septic shock (2C); and addressing goals of care, including treatment plans and end-of-life planning (as appropriate) (1B), as early as feasible, but within 72 hrs of intensive care unit admission (2C). Recommendations specific to pediatric severe sepsis include: therapy with face mask oxygen, high flow nasal cannula oxygen, or nasopharyngeal continuous PEEP in the presence of respiratory distress and hypoxemia (2C), use of physical examination therapeutic endpoints such as capillary refill (2C); for septic shock associated with hypovolemia, the use of crystalloids or albumin to deliver a bolus of 20 mL/kg of crystalloids (or albumin equivalent) over 5 to 10 mins (2C); more common use of inotropes and vasodilators for low cardiac output septic shock associated with elevated systemic vascular resistance (2C); and use of hydrocortisone only in children with suspected or proven "absolute"' adrenal insufficiency (2C).

CONCLUSIONS

Strong agreement existed among a large cohort of international experts regarding many level 1 recommendations for the best care of patients with severe sepsis. Although a significant number of aspects of care have relatively weak support, evidence-based recommendations regarding the acute management of sepsis and septic shock are the foundation of improved outcomes for this important group of critically ill patients.

Surviving Sepsis Campaign: international guidelines for management of severe sepsis and septic shock, 2012

OBJECTIVE

To provide an update to the "Surviving Sepsis Campaign Guidelines for Management of Severe Sepsis and Septic Shock," last published in 2008.

DESIGN

A consensus committee of 68 international experts representing 30 international organizations was convened. Nominal groups were assembled at key international meetings (for those committee members attending the conference). A formal conflict of interest policy was developed at the onset of the process and enforced throughout. The entire guidelines process was conducted independent of any industry funding. A stand-alone meeting was held for all subgroup heads, co- and vice-chairs, and selected individuals. Teleconferences and electronic-based discussion among subgroups and among the entire committee served as an integral part of the development.

METHODS

The authors were advised to follow the principles of the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system to guide assessment of quality of evidence from high (A) to very low (D) and to determine the strength of recommendations as strong (1) or weak (2). The potential drawbacks of making strong recommendations in the presence of low-quality evidence were emphasized. Recommendations were classified into three groups: (1) those directly targeting severe sepsis; (2) those targeting general care of the critically ill patient and considered high priority in severe sepsis; and (3) pediatric considerations.

RESULTS

Key recommendations and suggestions, listed by category, include: early quantitative resuscitation of the septic patient during the first 6 h after recognition (1C); blood cultures before antibiotic therapy (1C); imaging studies performed promptly to confirm a potential source of infection (UG); administration of broad-spectrum antimicrobials therapy within 1 h of the recognition of septic shock (1B) and severe sepsis without septic shock (1C) as the goal of therapy; reassessment of antimicrobial therapy daily for de-escalation, when appropriate (1B); infection source control with attention to the balance of risks and benefits of the chosen method within 12 h of diagnosis (1C); initial fluid resuscitation with crystalloid (1B) and consideration of the addition of albumin in patients who continue to require substantial amounts of crystalloid to maintain adequate mean arterial pressure (2C) and the avoidance of hetastarch formulations (1B); initial fluid challenge in patients with sepsis-induced tissue hypoperfusion and suspicion of hypovolemia to achieve a minimum of 30 mL/kg of crystalloids (more rapid administration and greater amounts of fluid may be needed in some patients (1C); fluid challenge technique continued as long as hemodynamic improvement is based on either dynamic or static variables (UG); norepinephrine as the first-choice vasopressor to maintain mean arterial pressure ≥65 mmHg (1B); epinephrine when an additional agent is needed to maintain adequate blood pressure (2B); vasopressin (0.03 U/min) can be added to norepinephrine to either raise mean arterial pressure to target or to decrease norepinephrine dose but should not be used as the initial vasopressor (UG); dopamine is not recommended except in highly selected circumstances (2C); dobutamine infusion administered or added to vasopressor in the presence of (a) myocardial dysfunction as suggested by elevated cardiac filling pressures and low cardiac output, or (b) ongoing signs of hypoperfusion despite achieving adequate intravascular volume and adequate mean arterial pressure (1C); avoiding use of intravenous hydrocortisone in adult septic shock patients if adequate fluid resuscitation and vasopressor therapy are able to restore hemodynamic stability (2C); hemoglobin target of 7-9 g/dL in the absence of tissue hypoperfusion, ischemic coronary artery disease, or acute hemorrhage (1B); low tidal volume (1A) and limitation of inspiratory plateau pressure (1B) for acute respiratory distress syndrome (ARDS); application of at least a minimal amount of positive end-expiratory pressure (PEEP) in ARDS (1B); higher rather than lower level of PEEP for patients with sepsis-induced moderate or severe ARDS (2C); recruitment maneuvers in sepsis patients with severe refractory hypoxemia due to ARDS (2C); prone positioning in sepsis-induced ARDS patients with a PaO (2)/FiO (2) ratio of ≤100 mm Hg in facilities that have experience with such practices (2C); head-of-bed elevation in mechanically ventilated patients unless contraindicated (1B); a conservative fluid strategy for patients with established ARDS who do not have evidence of tissue hypoperfusion (1C); protocols for weaning and sedation (1A); minimizing use of either intermittent bolus sedation or continuous infusion sedation targeting specific titration endpoints (1B); avoidance of neuromuscular blockers if possible in the septic patient without ARDS (1C); a short course of neuromuscular blocker (no longer than 48 h) for patients with early ARDS and a PaO (2)/FI O (2) <150 mm Hg (2C); a protocolized approach to blood glucose management commencing insulin dosing when two consecutive blood glucose levels are >180 mg/dL, targeting an upper blood glucose ≤180 mg/dL (1A); equivalency of continuous veno-venous hemofiltration or intermittent hemodialysis (2B); prophylaxis for deep vein thrombosis (1B); use of stress ulcer prophylaxis to prevent upper gastrointestinal bleeding in patients with bleeding risk factors (1B); oral or enteral (if necessary) feedings, as tolerated, rather than either complete fasting or provision of only intravenous glucose within the first 48 h after a diagnosis of severe sepsis/septic shock (2C); and addressing goals of care, including treatment plans and end-of-life planning (as appropriate) (1B), as early as feasible, but within 72 h of intensive care unit admission (2C). Recommendations specific to pediatric severe sepsis include: therapy with face mask oxygen, high flow nasal cannula oxygen, or nasopharyngeal continuous PEEP in the presence of respiratory distress and hypoxemia (2C), use of physical examination therapeutic endpoints such as capillary refill (2C); for septic shock associated with hypovolemia, the use of crystalloids or albumin to deliver a bolus of 20 mL/kg of crystalloids (or albumin equivalent) over 5-10 min (2C); more common use of inotropes and vasodilators for low cardiac output septic shock associated with elevated systemic vascular resistance (2C); and use of hydrocortisone only in children with suspected or proven "absolute"' adrenal insufficiency (2C).

CONCLUSIONS

Strong agreement existed among a large cohort of international experts regarding many level 1 recommendations for the best care of patients with severe sepsis. Although a significant number of aspects of care have relatively weak support, evidence-based recommendations regarding the acute management of sepsis and septic shock are the foundation of improved outcomes for this important group of critically ill patients.

[To go in-depth in the knowledge of the device to control fecal elimination in the critical patient]

OBJECTIVE

To describe the general characteristics of the patient and device use. To know retention balloon pressure (RBP) and related factors. To identify rate of leakage incidence, relocation and perineal damage due to the device (PSD) and related risk factors.

MATERIAL AND METHODS

An analytical observational, cross-sectional study conducted in a polyvalent ICU from June-December 2010 was performed. The sample included Flexi-Seal(®) carriers. Variables evaluated were patient and device use characteristics, RBP, leakage and quantity, relocation and reason, PSD, sedoanalgesia infusion, neuromuscular block, patient position, Flexi-Seal type catheter, ventilatory mode (VM), intra-abdominal pressure (IAP), mean intrathoracic pressure (MITP), PEEP, Glasgow, color-aspect, fecal consistency and volume. Significance P<.05.

RESULTS

Twenty-one patients were included, 52% male, aged 54±17 with 30 insertion episodes, Flexi-Seal-Signal(®) 33%, 10±8 days permanency, main indication 33% «diarrhea and injured skin»," 30% device removal «intolerance and/or spontaneous expulsion». Median (Me) PGR =40; RI (61-19) cmH2O. Factors associated to higher PGR: SCI absence, prone-decubitus position, leakage, relocation, conventional Flexi-Seal(®), MV, lower PEEP and IMP, Color-aspect, higher MITP. Leakage, relocation and PSD incidence density 43, 30 and 2 cases/100 days of catheter, respectively. Leakage and relocation risk factors: higher PGR, Glasgow and fecal volume, lower MITP, MV, assisted-spontaneous mode OR 2.5 CI (1.6-3.8) and OR 1.7(1.1-2.7), absence SCI OR 3.3 (2.2-5.1) and OR 2.4(1.5-3.8), absence neuromuscular block OR 2.4 (1.4-3.9) and OR 1.8 (1.1-3.1), Flexi-Seal(®) conventional OR 2.7(1.7-4.1) and OR 2 (1.2-3.3), respectively. Leakage risk factors: color-aspect, supine position, lower IMP and PEEP.

CONCLUSIONS

Monitoring RBP may alert us about leakage presence and relocation need. Knowing associated risk factors to RBP, leakage and relocation would help to develop strategies to reduce their high incidence rate such as decreasing RBP by reducing inflated volume.

Relationship between intra-abdominal pressure and indocyanine green plasma disappearance rate: hepatic perfusion may be impaired in critically ill patients with intra-abdominal hypertension

Background

Monitoring hepatic blood flow and function might be crucial in treating critically ill patients. Intra-abdominal hypertension is associated with decreased abdominal blood flow, organ dysfunction, and increased mortality. The plasma disappearance rate (PDR) of indocyanine green (ICG) is considered to be a compound marker for hepatosplanchnic perfusion and hepatocellular membrane transport and correlates well with survival in critically ill patients. However, correlation between PDR_ICG and intra-abdominal pressure (IAP) remains poorly understood. The aim of this retrospective study was to investigate the correlation between PDR_ICG and classic liver laboratory parameters, IAP and abdominal perfusion pressure (APP). The secondary goal was to evaluate IAP, APP, and PDR_ICG as prognostic factors for mortality.

Methods

A total of 182 paired IAP and PDR_ICG measurements were performed in 40 critically ill patients. The mean values per patient were used for comparison. The IAP was measured using either a balloon-tipped stomach catheter connected to an IAP monitor (Spiegelberg, Hamburg, Germany, or CiMON, Pulsion Medical Systems, Munich, Germany) or a bladder FoleyManometer (Holtech Medical, Charlottenlund, Denmark). PDR_ICG was measured at the bedside using the LiMON device (Pulsion Medical Systems, Munich, Germany). Primary endpoint was hospital mortality.

Results

There was no significant correlation between PDR_ICG and classic liver laboratory parameters, but PDR_ICG did correlate significantly with APP (R = 0.62) and was inversely correlated with IAP (R = -0.52). Changes in PDR_ICG were associated with significant concomitant changes in APP (R = 0.73) and opposite changes in IAP (R = 0.61). The IAP was significantly higher (14.6 ± 4.6 vs. 11.1 ± 5.3 mmHg, p = 0.03), and PDR_ICG (10 ± 8.3 vs. 15.9 ± 5.2%, p = 0.02) and APP (43.6 ± 9 vs. 57.9 ± 12.2 mmHg, p < 0.0001) were significantly lower in non-survivors.

Conclusions

PDR_ICG is positively correlated to APP and inversely correlated to IAP. Changes in APP are associated with significant concomitant changes in PDR_ICG, while changes in IAP are associated with opposite changes in PDR_ICG, suggesting that an increase in IAP may compromise hepatosplanchnic perfusion. Both PDR_ICG and IAP are correlated with outcome. Measurement of PDR_ICG may be a useful additional clinical tool to assess the negative effects of increased IAP on liver perfusion and function.

Vacuum and mesh-mediated fascial traction for primary closure of the open abdomen in critically ill surgical patients

BACKGROUND

Several temporary abdominal closure techniques have been used in the management of open abdomen. Failure to achieve delayed primary fascial closure results in a large ventral hernia. This retrospective analysis evaluated whether the use of vacuum-assisted closure and mesh-mediated fascial traction (VACM) as temporary abdominal closure improved the delayed primary fascial closure rate compared with non-traction methods.

METHODS

Patients treated with an open abdomen between 2004 and 2010 were analysed.

RESULTS

Among 50 patients treated with VACM and 54 using non-traction techniques (control group), the delayed primary fascial closure rate was 78 and 44 per cent respectively (P < 0·001); rates among those who survived to abdominal closure were 93 and 59 per cent respectively. Independent predictors of delayed primary fascial closure in multivariable logistic regression analysis were the use of VACM (odds ratio (OR) 4·43, 95 per cent confidence interval 1·64 to 11·99) and diagnosis other than peritonitis, severe acute pancreatitis or ruptured abdominal aortic aneurysm (OR 3·45, 1·07 to 11·04), which represented the main diagnoses. Prophylactic open abdomen was used to inhibit the development of intra-abdominal hypertension more frequently in the VACM group (28 versus 7 per cent; P = 0·008). Twelve per cent of patients in the VACM group developed an enteroatmospheric fistula compared with 19 per cent of control patients. Among survivors, three of 31 treated with VACM and 17 of 36 controls were left with a planned ventral hernia (P = 0·001).

CONCLUSION

The indication for open abdomen contributed to the probability of delayed primary fascial closure. VACM resulted in a higher fascial closure rate and lower planned hernia rate than methods that did not provide fascial traction.

Renal dysfunction in heart failure

Renal dysfunction is a common, important comorbidity in patients with both chronic and acute heart failure (HF). Chronic kidney disease and worsening renal function (WRF) are associated with worse outcomes, but our understanding of the complex bidirectional interactions between the heart and kidney remains poor. When addressing these interactions, one must consider the impact of intrinsic renal disease resulting from medical comorbidities on HF outcomes. WRF may result from any number of important processes. Understanding the role of each of these factors and their interplay are essential in understanding how to improve outcomes in patients with renal dysfunction and HF.

Current controversies in fluid resuscitation in acute pancreatitis: a systematic review

Acute pancreatitis (AP) is a common inflammatory disorder of the pancreas resulting in considerable morbidity and mortality. Aggressive intravenous fluid resuscitation generally is recommended in all patients with AP and remains the cornerstone of management of these patients. However, the optimal rate, type, and the goal of resuscitation remain unclear. The purpose of this review was to give an insight about the pathophysiologic alterations in the pancreatic microcirculation that occur in AP, the markers for early recognition of severity of pancreatitis, the optimal fluid, and timing and extent of fluid resuscitation. An early elevated hematocrit, blood urea nitrogen, or creatinine should prompt clinicians to institute more intensive early resuscitation measures. Crystalloids are the currently recommended fluids for management of these patients. Current studies are underway to determine the optimal end points of fluid resuscitation that determine outcome.

The effect of body position on compartmental intra-abdominal pressure following liver transplantation

BACKGROUND

Current assumptions rely on intra-abdominal pressure (IAP) being uniform across the abdominal cavity. The abdominal contents are, however, a heterogeneous mix of solid, liquid and gas, and pressure transmission may not be uniform. The current study examines the upper and lower IAP following liver transplantation.

METHODS

IAP was measured directly via intra-peritoneal catheters placed at the liver and outside the bladder. Compartmental pressure data were recorded at 10-min intervals for up to 72 h following surgery, and the effect of intermittent posture change on compartmental pressures was also studied. Pelvic intra-peritoneal pressure was compared to intra-bladder pressure measured via a FoleyManometer.

RESULTS

A significant variation in upper and lower IAP of 18% was observed with a range of differences of 0 to 16 mmHg. A sustained difference in inter-compartmental pressure of 4 mmHg or more was present for 23% of the study time. Head-up positioning at 30° provided a protective effect on upper intra-abdominal pressure, resulting in a significant reduction in all patients. There was excellent agreement between intra-bladder and pelvic pressure.

CONCLUSIONS

A clinically significant variation in inter-compartmental pressure exists following liver transplantation, which can be manipulated by changes to body position. The existence of regional pressure differences suggests that IAP monitoring at the bladder alone may under-diagnose intra-abdominal hypertension and abdominal compartment syndrome in these patients. The upper and lower abdomen may need to be considered as separate entities in certain conditions.

Moderate intra-abdominal hypertension is associated with an increased lactate-pyruvate ratio in the rectus abdominis muscle tissue: a pilot study during laparoscopic surgery

Background

The development of intra-abdominal hypertension [IAH] in critically ill patients admitted to the ICU is an independent predictor of mortality. In an attempt to find an early, clinically relevant metabolic signal of modest IAH, we investigated abdominal wall metabolite concentrations in a small group of patients undergoing laparoscopic surgery. We hypothesized that elevated intra-abdominal pressure [IAP] due to pneumoperitoneum leads to an increased lactate/pyruvate [L/P] ratio in the rectus abdominis muscle [RAM], indicating anaerobic metabolism.

Method

Six patients scheduled for elective laparoscopic gastric fundoplication were studied. Two hours before surgery, a microdialysis catheter (CMA 60, CMA Small Systems AB, Solna, Sweden) was inserted into the RAM under local anaesthesia. Catheter placement was confirmed by ultrasound. The microdialysis perfusion rate was set at 0.3 μL/min. Dialysate was collected hourly prior to pneumoperitoneum, during pneumoperitoneum, and for 2 h after pneumoperitoneum resolution. IAP was maintained at 12 to 13 mmHg during the surgery. The glucose, glycerol, pyruvate and lactate contents of the dialysate were measured.

Results

The median (interquartile range) L/P ratio was 10.3 (7.1 to 15.5) mmol/L at baseline. One hour of pneumoperitoneum increased the L/P ratio to 16.0 (13.6 to 35.3) mmol/L (p = 0.03). The median pneumoperitoneum duration was 86 (77 to 111) min. The L/P ratio at 2 h post-pneumoperitoneum was not different from that at baseline (p = 1.0). No changes in glycerol or glucose levels were observed.

Conclusions

IAH of 12 to 13 mmHg, even for a relatively short duration, is associated with metabolic changes in the abdominal wall muscle tissue of patients undergoing laparoscopic surgery. We suggest that tissue hypoperfusion occurs even during a modest increase in IAP, and intramuscular metabolic monitoring could therefore serve as an early warning sign of deteriorating tissue perfusion.

[Utility of monitoring intra-abdominal pressure in critically ill children]

OBJECTIVE

To assess the usefulness of intra-abdominal pressure (IAP) measurement, by the intra-vesical method, in order to identify those patients at risk of developing intra-abdominal hypertension, as well as to analyse the factors that affect the IAP, and to determine their influence on the prognosis in critically ill patients.

PATIENTS AND METHODS

Prospective observational study in critically ill children in whom the IAP was monitored as soon as signs of intra-abdominal hypertension appeared. The following variables were analysed: age, sex, reason for admission, underlying disease, previous surgeries, blood pressure, heart rate, central venous pressure, urine output, inotropic therapy, sedation, muscle relaxation, mechanical ventilation, renal replacement techniques, extracorporeal membrane oxygenation, and mortality.

RESULTS

A total of 39 patients were studied. At 24hours from initiating the monitoring of IAP, 74.4% showed IAP ≥ 12mmHg, 33.3%>15mmHg, and 15.4%>20mmHg. After 48hours, 59% had intra-abdominal hypertension. There was a correlation between the central venous pressure (CVP) and IAP at 24 and 48hours (r=0.500, P=.001 and r=0.360, P=.040, respectively). There was no correlation with the other parameters. Only 9 patients required urgent decompression and none developed abdominal compartment syndrome.

CONCLUSIONS

IAP monitoring can be useful to diagnose and to promptly treat intra-abdominal hypertension, and thus to prevent the abdominal compartment syndrome. Therefore, it should be measured in critically ill children with abdominal pathology.

Relationship between Abdominal Pressure, Pulmonary Compliance, and Cardiac Preload in a Porcine Model

Rationale. Elevated intra-abdominal pressure (IAP) may compromise respiratory and cardiovascular function by abdomino-thoracic pressure transmission. We aimed (1) to study the effects of elevated IAP on pleural pressure, (2) to understand the implications for lung and chest wall compliances and (3) to determine whether volumetric filling parameters may be more accurate than classical pressure-based filling pressures for preload assessment in the setting of elevated IAP. Methods. In eleven pigs, IAP was increased stepwise from 6 to 30 mmHg. Hemodynamic, esophageal, and pulmonary pressures were recorded. Results. 17% (end-expiratory) to 62% (end-inspiratory) of elevated IAP was transmitted to the thoracic compartment. Respiratory system compliance decreased significantly with elevated IAP and chest wall compliance decreased. Central venous and pulmonary wedge pressure increased with increasing IAP and correlated inversely (r = -0.31) with stroke index (SI). Global end-diastolic volume index was unaffected by IAP and correlated best with SI (r = 0.52). Conclusions. Increased IAP is transferred to the thoracic compartment and results in a decreased respiratory system compliance due to decreased chest wall compliance. Volumetric filling parameters and transmural filling pressures are clearly superior to classical cardiac filling pressures in the assessment of cardiac preload during elevated IAP.

Tension pneumoperitoneum in a child resulting from high-frequency oscillatory ventilation: a case report and review of the literature

An 18-month-old male infant was placed on high-frequency oscillatory ventilation for profound hypoxemia and subsequently developed tension pneumoperitoneum. He underwent a bedside exploratory laparotomy for suspected perforated viscus. No intestinal perforation was identified, and a diagnosis of tension pneumoperitoneum secondary to pneumatosis cystoides intestinalis was made. To our knowledge, this is the only report of a pediatric patient developing tension pneumoperitoneum from high-frequency oscillatory ventilation. A review of the literature examines the differential diagnosis, physiology, and treatment of tension pneumoperitoneum.

Intra-abdominal Hypertension and Abdominal Compartment Syndrome

Intra-abdominal hypertension has a prevalence of at least 50% in the critically ill population and has been identified as an independent risk factor for death. Yet, many of the members of the critical care team do not assess for intra-abdominal hypertension and are unaware of the consequences of untreated intra-abdominal hypertension. These consequences can be abdominal compartment syndrome, multisystem organ failure, and death. This article provides an overview of the pathophysiology of intra-abdominal hypertension and abdominal compartment syndrome. In addition, the evidence-based definitions, guidelines, and recommendations of the World Society of the Abdominal Compartment Syndrome are presented.

Incidence, Risk Factors and Outcome Associations of Intra-Abdominal Hypertension in Critically Ill Patients

Intra-abdominal hypertension (IAH) and abdominal compartment syndrome (ACS) are significantly associated with morbidity and mortality. We performed a prospective observational study and applied recently published consensus criteria to measure and describe the incidence of IAH and ACS, identify risk factors for their development and define their association with outcomes. We studied 100 consecutive patients admitted to our general intensive care unit. We recorded relevant demographic, clinical data and maximal (max) and mean intra-abdominal pressure (IAP). We measured and defined IAH and ACS using consensus guidelines. Of our study patients, 42% (by IAPmax) and 38% (by IAPmean) had IAH. Patients with IAH had greater mean body mass index (30.4±9.6 vs 25.4±5.6 kg/m2, P=0.005), Acute Physiology and Chronic Health Evaluation III score (78.2±28.5 vs 65.5±29.2, P=0.03) and central venous pressure (12.8±4.8 vs 9.2±3.5 mmHg, P <0.001), lower abdominal perfusion pressure (67.6±13.5 vs 79.3±17.3 mmHg, P <0.001) and lower filtration gradient (51.2±14.8 vs 71.6±17.7 mmHg; P <0.001). Risk factors associated with IAH were body mass index ≥30 (P <0.001), higher central venous pressure (P <0.001), presence of abdominal infection (P=0.005) and presence of sepsis on admission (P=0.035). Abdominal compartment syndrome developed in 4% of patients. IAP was not associated with an increased risk of mortality after adjusting for other confounders. We conclude that, in a general population of critically ill patients, using consensus guidelines, IAH was common and significantly associated with obesity and sepsis on admission. In a minority of patients, IAH was associated with abdominal compartment syndrome. In this cohort IAH was not associated with an increased risk of mortality.

Abdominal compartment syndrome - Intra-abdominal hypertension: Defining, diagnosing, and managing

Abdominal compartment syndrome (ACS) and intra-abdominal hypertension (IAH) are increasingly recognized as potential complications in intensive care unit (ICU) patients. ACS and IAH affect all body systems, most notably the cardiac, respiratory, renal, and neurologic systems. ACS/IAH affects blood flow to various organs and plays a significant role in the prognosis of the patients. Recognition of ACS/IAH, its risk factors and clinical signs can reduce the morbidity and mortality associated. Moreover, knowledge of the pathophysiology may help rationalize the therapeutic approach. We start this article with a brief historic review on ACS/IAH. Then, we present the definitions concerning parameters necessary in understanding ACS/IAH. Finally, pathophysiology aspects of both phenomena are presented, prior to exploring the various facets of ACS/IAH management.

Reinforced tension line suture closure after midline laparotomy in emergency surgery

Midline laparotomy is an emergency surgical operation frequently performed in cases of intra-abdominal pathology. Closure of the incision is usually done by continuous suturing by mass closure. In an emergency operation the intra-abdominal milieu is usually contaminated leading to gut oedema and, hence, an increase in postoperative intra-abdominal pressure. It is complicated by wound dehiscence, burst abdomen, etc. The cause of this complication is an increase in horizontal tensile forces on the site of the insertion of sutures which cuts the sheath. In this technique of reinforced tension line suture peak tensile forces are distributed from the suture base to the surrounding tissue through a horizontal suture, thereby preventing the suture from cutting through the tissue. From July 2007 to June 2009 patients requiring laparotomy were randomly divided into test and control groups by a 'closed envelope' technique. Their postoperative intra-abdominal pressure was recorded by urinary bladder catheter manometry. The result of this technique was compared with the incidence of burst abdomen in cases where it was closed by continuous suture. A total of 190 patients underwent laparotomy. In 90 the abdomen was closed by reinforced tension line (RTL) and in 100 patients by continuous suturing. None of the RTL group had a burst abdomen. Thirteen who had closure by continuous suture had a burst abdomen. The analysis of the results was done using the chi-square test. On comparing the incidence of burst abdomen in cases operated by continuous suture technique and by RTL, the P value was found to be 0.0026 which is highly significant. On analysis of the incidence of burst abdomen in cases having a grade II intra-abdominal pressure the P value was found to be 0.0009 which is highly significant. Closure of midline incision by RTL reduces the incidence of burst abdomen. Registration No. PROVCTRI/2008/091/000269 (http://www.ctri.in).

Role of dysfunctional maternal venous hemodynamics in the pathophysiology of pre-eclampsia: a review

The venous compartment has an important function in regulation and control of cardiac output. Abnormalities of cardiac output have been found in early gestational stages of both early- and late-onset pre-eclampsia. The venous compartment also maintains the balance between circulating and non-circulating blood volumes and regulates the amount of reserve blood stored in the splanchnic venous bed. It is well known that adaptive regulation of maternal blood volume is disturbed in pre-eclampsia. Abnormal venous hemodynamics and venous congestion are responsible for secondary dysfunction of several organs, such as the kidneys in cardiorenal syndrome and the liver in cardiac cirrhosis. Renal and liver dysfunctions are among the most relevant clinical features of pre-eclampsia. Doppler sonography studies have shown that the maternal venous compartment is subject to gestational adaptation, and that blood flow characteristics at the level of renal interlobar and hepatic veins are different in pre-eclampsia compared with uncomplicated pregnancy. In comparison to late-onset pre-eclampsia, in early-onset pre-eclampsia venous Doppler flow abnormalities are more prominent and present up to weeks before clinical symptoms. This paper reviews the growing evidence that dysfunction of maternal venous hemodynamics is part of the pathophysiology of pre-eclampsia and may perhaps be more important than is currently considered. Doppler sonography is a safe and easily performed method with which to study maternal venous hemodynamics. Therefore, exploring the role of maternal venous hemodynamics using Doppler sonography is an exciting new research topic for those who are interested in cardiovascular background mechanisms, as well as prediction and clinical work-up of pre-eclampsia.

Intra-abdominal pressure and abdominal perfusion pressure: which is a better marker of severity in patients with severe acute pancreatitis

BACKGROUND

Intra-abdominal hypertension is common in patients with severe acute pancreatitis. The aim of this study was to assess the clinical relevance of intra-abdominal pressure and abdominal perfusion pressure in the first 72 h after admission during severe acute pancreatitis.

METHODS

From January 2009 to February 2011, 50 patients admitted for severe acute pancreatitis were included in this prospective, observational study. The intra-abdominal pressure and abdominal perfusion pressure level were repeatedly measured every 12 h during the first 72 h. The maximum and the mean values of intra-abdominal pressure and the minimum and mean values of abdominal perfusion pressure were used for analysis.

RESULTS

Both the maximum and mean levels of intra-abdominal pressure were significantly different between patients with or without kinds of clinical variables. But for abdominal perfusion pressure, difference could only be detected in terms of need of vasoactive drugs. Besides that, different from abdominal perfusion pressure, intra-abdominal pressure is associated with high incidence rates of MODS and secondary infection.

CONCLUSION

Compared with abdominal perfusion pressure, intra-abdominal pressure is much more valuable as an early marker of the evolution and complications of severe acute pancreatitis.

Beneficial effects of theophylline infusions in surgical patients with intra-abdominal hypertension

BACKGROUND

Intra-abdominal hypertension (IAH) can cause high mortality. Recently, we found that IAH was associated with increased serum levels of adenosine and interleukin 10. Our present "hypothesis-generated study" was based on the above mentioned results.

MATERIALS AND METHODS

In this uncontrolled clinical trial, a total of 78 patients with IAH were enrolled representing a 13-20 mmHg range of intra-abdominal pressure (IAP). Patients requiring surgical abdominal decompression were excluded. Patients were treated with the following protocols: standard supportive therapy (ST, n = 38) or ST plus infusion with the adenosine receptor antagonist theophylline (T, n = 40). Over the 5-day measurement period, IAP was monitored continuously and serum adenosine concentration and other clinical and laboratory measurements were monitored daily. Mortality was followed for the first 30 days following the diagnosis of IAH.

RESULTS

Mortality of ST patients was 55%, which is compatible to other studies. Serum adenosine concentration was found to be directly proportional to IAP. Of the 40 patients receiving T treatment, survival was 100%. An increased survival related to theophylline infusion correlated with improving serum concentrations of IL-10, urea, and creatinine, as well as 24-h urine output, fluid balance, mean arterial pressure, and O(2)Sat.

CONCLUSIONS

Adenosine receptor antagonism with T following IAH diagnosis resulted in markedly reduced mortality in patients with moderated IAH (<20 mmHg). Theophylline-associated mortality reduction may be related to improved renal perfusion and improved MAP, presumably caused by adenosine receptor blockade. Because this study was not a randomized controlled study, these compelling observations require further multicentric clinical confirmation.

Should mechanical ventilation be guided by esophageal pressure measurements?

PURPOSE OF REVIEW

Despite the well recognized role of mechanical ventilation in lung injury, appropriate surrogate markers to guide titration of ventilator settings remain elusive. One would like to strike a balance between protecting aerated units from overdistension while recruiting unstable units, thereby reducing tissue damage associated with their cyclic recruitment and derecruitment. To do so requires some estimate of the topographical distribution of parenchymal stress and strain.

RECENT FINDINGS

Recent studies have highlighted the importance of chest wall recoil and its effect on pleural pressure (Ppl) in determining lung stress. Although esophageal pressure (Pes) has traditionally been used to measure the average Ppl in normal upright patients, in recumbent acute lung injury/acute respiratory distress syndrome patients Pes-based estimates of Ppl are subject to untestable assumptions. Nevertheless, Pes measurements in recumbent patients with injured lungs strongly suggest that Ppl over dependent parts of the lung can exceed airway pressure by substantial amounts. Moreover, results of a pilot study in which Pes was used to titrate positive end-expiratory pressure (PEEP) suggest clinical benefit.

SUMMARY

Notwithstanding its theoretical limitations, esophageal manometry has shown promise in PEEP titration and deserves further evaluation in a larger trial on patients with injured lungs.

Chest wall mechanics and abdominal pressure during general anaesthesia in normal and obese individuals and in acute lung injury

PURPOSE OF REVIEW

This article discusses the methods available to evaluate chest wall mechanics and the relationship between intraabdominal pressure (IAP) and chest wall mechanics during general anaesthesia in normal and obese individuals, as well as in acute lung injury/acute respiratory distress syndrome.

RECENT FINDINGS

The interactions between the abdominal and thoracic compartments pose a specific challenge for intensive care physicians. IAP affects respiratory system, lung and chest wall elastance in an unpredictable way. Thus, transpulmonary pressure should be measured if IAP is more than 12 mmHg or if chest wall elastance is compromised for other reasons, even though the absolute values of pleural and transpulmonary pressures are not easily obtained at bedside. We suggest defining intraabdominal hypertension (IAH) as IAP at least 20 mmHg and abdominal compartment syndrome (ACS) as IAP at least 20 mmHg associated with failure of one or more organs, although further studies are required to confirm this hypothesis. Additionally, in the presence of IAH, controlled mechanical ventilation should be applied and positive end-expiratory pressure individually titrated. Prophylactic open abdomen should be considered in the presence of ACS.

SUMMARY

Increased IAP markedly affects respiratory function and complicates patient management. Frequent assessment of IAP is recommended.

Cardiorenal syndrome: diagnosis, treatment, and clinical outcomes

The pathophysiologic interactions that link the heart and kidney are multiple and complex, and have been grouped under the umbrella term "cardiorenal syndrome." In the setting of acute decompensated heart failure, worsening renal function has been directly associated with poor clinical prognosis and complicates treatment. However, the pathophysiology underlying acute cardiorenal syndrome remains incompletely understood and treatment options remain limited. Traditionally, the development of worsening renal function in acute decompensated heart failure has been attributed to renal arterial underfilling due to reduced cardiac output or intravascular volume depletion. However, increasing data have expanded our understanding of the roles that venous congestion and intra-abdominal pressure play in driving renal injury, with important implications for therapeutic management and the development of novel renal-sparing therapies.

[Intraabdominal hypertension and abdominal compartment syndrome]

Although intraabdominal pressure (IAP) has been studied for more than 100 years, the concepts of intraabdominal hypertension (IAH) and abdominal compartmental syndrome (ACS) have only been developed as clinical entities of interest in intensive care in the last 5 years. At the first Congress on Abdominal Compartment Syndrome in December 2004, a series of definitions were established, which were published in 2006. IAH is defined as IAP ≥ 12 mmHg and is classified in four severity grades, the maximum grade being ACS, with the development of multiorgan failure. The incidence of IAH in patients in intensive care units is high, around 30% at admission and 64% in those with a length of stay of 7 days. The increase in IAP leads to reduced vascular flow to the splenic organs, increased intrathoracic pressure and decreased venous return, with a substantial reduction in cardiac output. If IAH persists, these physiopathologic episodes are followed by the development of multiorgan failure with renal, cardiocirculatory and respiratory failure and intestinal ischemia. Mortality from untreated ACS is higher than 60%. The only treatment for ACS is surgical decompression. In patients with moderate IAH, medical treatment should be optimized, based on the following measures: a) serial IAP monitoring; b) optimization of systemic perfusion and the function of the distinct systems in patients with high IAP; c) instauration of specific measures to decrease IAP; and d) early surgical decompression for refractory IAH. The application of the medical measures that can reduce IAP and early abdominal decompression in ACS improve survival in critically ill patients with IAH.

Intraperitoneal pressure and intra-abdominal pressure: are they the same?

BACKGROUND

In peritoneal dialysis (PD), a standard therapy for patients with end-stage renal disease (ESRD), the effects of using the peritoneum as an exchange membrane and of dialysate dwelling within the peritoneal cavity creates some mechanical changes, including an increase in intraperitoneal pressure (IPP) that might lead to intra-abdominal hypertension (IAH) and abdominal compartment syndrome (ACS). The diagnosis of IAH and ACS depend on intra-abdominal measurement of IAP by an indirect technique. There is no clear distinction between IPP and intra-abdominal pressure (IAP). Our objective in this study was to find if there is real difference between IPP and IAP.

METHODS

This study was conducted at the PD unit of King Fahd Hospital of the University, Al-Khobar, between July 2008 and January 2009. To be included, patients had to have known ESRD for at least 5 years, to be 18 years of age or older at enrollment, with stable body weight and blood pressure, and with no clinical signs of overhydration. Patients with congestive heart failure III and IV (New York Heart Association criteria) and severe pulmonary disease, psychiatric illnesses, neurogenic bladder, known history of peritonitis, or medical or surgical abdominal intervention in the preceding 3 months were excluded. We measured IAP by the direct technique through the peritoneal catheter and by an indirect technique using an intravesical catheter.

RESULTS

The 25 patients who met the inclusion criteria included 13 men and 12 women, with a mean age of 53 ± 2 years (range: 18 - 76 years). The predominant causes of ESRD were diabetes mellitus and glomerulonephritis. Mean IPP in the dry state (supine) was 9.49 ± 5 mmHg, and mean IAP was 9.4 ± 5.4 mmHg (p = 0.9). In the dry state (erect), the mean IPP increased to 16.9 ± 7.2 mmHg, and the mean IAP, to 16.4 ± 6.9 mmHg (p = 0.8). In the filled state (supine), mean IPP was 12.6 ± 4.7 mmHg, and mean IAP, 12.8 ± 4.8 mmHg (p = 0.88); the erect pressures were 21.4 ± 7 mmHg and 21.6 ± 6.9 mmHg respectively (p = 0.9).

CONCLUSIONS

Our findings indicate that there is no statistical difference between IPP and IAP in either the erect or the supine position.

Prospective study of intra-abdominal pressure following major elective abdominal surgery

BACKGROUND

Studies in emergency surgical patients have shown that raised intra-abdominal pressure may adversely affect organ function. The major aim of the present study was to establish the incidence of intra-abdominal hypertension (IAH) in patients undergoing major elective abdominal surgery. A secondary aim was to determine if the development of IAH was associated with poorer outcome.

METHODS

Patients undergoing major elective general surgical procedures were recruited to a prospective study in which intra-abdominal pressure was measured for 72 h postoperatively. Outcome data were collected on all patients.

RESULTS

A total of 42 patients with a median age of 63.5 years were studied. Five patients (12%) developed IAH, but this did not lead to a significant increase in the incidence of major organ dysfunction. There was no significant difference in the median length of hospital stay. However the development of IAH was associated with delayed return to oral diet (p < 0.05).

CONCLUSIONS

Intra-abdominal hypertension occurs in 12% of patients following major elective abdominal surgery and leads to a significantly delayed return to oral diet, but not to an increased length of hospital stay or increased incidence of major organ dysfunction.

Massive gastric dilatation and anuria resolved with naso-gastric tube decompression

We report for the first time a case of acute kidney injury associated with severe gastric distention after a laparoscopic Nissen-Rossetti fundoplication of the stomach for hiatal hernia. An abdominal compartment syndrome secondary to intra-abdominal hypertension was suspected. Naso-gastric tube decompression resulted in immediate resaturation of the diuresis and progressive recovery of renal function.

Effect of increased intra-abdominal pressure and decompressive laparotomy on aerated lung volume distribution

Increased intra-abdominal pressure (IAP) is common in intensive care patients, affecting aerated lung volume distribution. The current study deals with the effect of increased IAP and decompressive laparotomy on aerated lung volume distribution. The serial whole-lung computed tomography scans of 16 patients with increased IAP were retrospectively analyzed between July 2006 and July 2008 and compared to controls. The IAP increased from (12.1+/-2.3) mmHg on admission to (25.2+/-3.6) mmHg (P<0.01) before decompressive laparotomy and decreased to (14.7+/-2.8) mmHg after decompressive laparotomy. Mean time from admission to decompressive laparotomy and length of intensive-care unit (ICU) stay were 26 h and 16.2 d, respectively. The percentage of normally aerated lung volume on admission was significantly lower than that of controls (P<0.01). Prior to decompressive laparotomy, the total lung volume and percentage of normally aerated lung were significantly less in patients compared to controls (P<0.01), and the absolute volume of non-aerated lung and percentage of non-aerated lung were significantly higher in patients (P<0.01). Peak inspiratory pressure, partial pressure of carbon dioxide in arterial blood, and central venous pressure were higher in patients, while the ratio of partial pressure of arterial O(2) to the fraction of inspired O(2) (PaO(2)/FIO(2)) was decreased relative to controls prior to laparotomy. An approximately 1.8 cm greater cranial displacement of the diaphragm in patients versus controls was observed before laparotomy. The sagittal diameter of the lung at the T6 level was significantly increased compared to controls on admission (P<0.01). After laparotomy, the volume and percentage of non-aerated lung decreased significantly while the percentage of normally aerated lung volume increased significantly (P<0.01). In conclusion, increased IAP decreases total lung volume while increasing non-aerated lung volume. Decompressive laparotomy is associated with resolution of these effects on lung volumes.

Understanding of Abdominal Compartment Syndrome among Pediatric Healthcare Providers

Background. The sparse reporting of abdominal compartment syndrome (ACS) in the pediatric literature may reflect inadequate awareness and recognition among pediatric healthcare providers (HCP). Purpose. To assess awareness of ACS, knowledge of the definition and intraabdominal pressure (IAP) measurement techniques used among pediatric HCP. Method. A written survey distributed at two pediatric critical care conferences. Results. Forty-seven percent of 1107 questionnaires were completed. Participants included pediatric intensivists, pediatric nurses, and others. Seventy-seven percent (n = 513) of participants had heard of ACS. Only 46.8% defined ACS correctly. The threshold IAP value used to define ACS was variable among participants. About one-quarter of participants (83/343), had never measured IAP. Conclusion. Twenty-three percent of HCP surveyed were unaware of ACS. Criteria used to define ACS were variable. Focused education on recognition of ACS and measuring IAP should be promoted among pediatric HCP.

Decompressive laparotomy for abdominal compartment syndrome in children: before it is too late

PURPOSE

Abdominal compartment syndrome (ACS) in children is an infrequently reported, rapidly progressive, and often lethal condition underappreciated in the pediatric population. This underrecognition can result in a critical delay in diagnosis causing increased morbidity and mortality. This study examines the clinical course of patients treated for ACS at our institution.

METHODS

A review of children requiring an emergency laparotomy (n = 264) identified 26 patients with a diagnosis of ACS. ACS was defined as sustained intraabdominal hypertension (bladder pressure >12 mm Hg) that was associated with new onset organ dysfunction or failure.

RESULTS

Patients ranged in age from 3 months to 17 years old and were cared for in the pediatric intensive care unit (PICU). Twenty-seven percent (n = 7) were transferred from referring hospitals, 50% (n = 13) were admitted directly from the emergency department, and 23% (n = 6) were inpatients before being transferred to PICU. Admission diagnoses included infectious enterocolitis (n = 12), postsurgical procedure (n = 10), and others (n = 4). Patients progressed to ACS rapidly, with most requiring decompressive laparotomy within 8 hours of PICU admission (range, <1-96 hours). Preoperatively, all patients had maximum ventilatory support and oliguria, 85% (n = 22) required vasopressors/inotropes, and 31% (n = 8) required hemodialysis. Mean bladder pressure was 25 mm Hg (range, 12-44 mm Hg). In 42% (n = 11), cardiac arrest preceeded decompressive laparotomy. All patients showed evidence of tissue ischemia before decompressive laparotomy with an average preoperative lactate of 8 (range, 1.2-20). Decompressive laparotomy was done at the bedside in the PICU in 13 patients and in the operating room in 14 patients. Abdominal wounds were managed with open vacuum pack or silastic silo dressings. Physiologic data including fluid resuscitation, oxygen index, mean airway pressure, vasopressor score, and urine output were recorded at 6-hour intervals beginning 12 hours before decompressive laparotomy and extending 12 hours after operation. The data demonstrate improvement of all physiologic parameters after decompressive laparotomy except for urine output, which continued to be minimal 12 hours post intervention. Mortality was 58% (n = 15) overall. The only significant factor related to increased mortality was bladder pressure (P = .046; odds ratio, 1.258). Cardiac arrest before decompressive laparotomy, need for hemodialysis, and transfer from referring hospital also trended toward increased mortality but did not reach significance.

CONCLUSION

Abdominal compartment syndrome in children carries a high mortality and may be a consequence of common childhood diseases such as enterocolitis. The diagnosis of ACS and the potential need for emergent decompressive laparotomy may be infrequently discussed in the pediatric literature. Increased awareness of ACS may promote earlier diagnosis, treatment, and possibly improve outcomes.

Linea Alba Fasciotomy: A Novel Alternative in Trauma Patients with Secondary Abdominal Compartment Syndrome

Polytrauma patients needing aggressive resuscitation can develop intra-abdominal hypertension (IAH) with subsequent secondary abdominal compartment syndrome (SACS). After patients fail medical therapy, decompressive laparotomy is the surgical last resort. In patients with severe pancreatitis SACS, the use of linea alba fasciotomy (LAF) is an effective intervention to lower IAH without the morbidity of laparotomy. A pilot study of LAF was designed to evaluate its benefit in patients with SACS polytrauma. We conducted an observational study of blunt injury polytrauma patients undergoing LAF. Variables measured before and after LAF included intra-abdominal pressure (IAP, mmHg), abdominal perfusion pressure (APP, mmHg), right ventricular end diastolic volume index (RVEDVI, mL/m2), and ejection fraction. Of the five trauma patients with SACS, the mean age was 36 ± 17, four (80%) male with an Injury Severity Score of 27 ± 9. Pre- and post-LAF, IAP was 20.6 ± 4.7 and 10.6 ± 2.7 ( P < 0.0001), APP 55.2 ± 5.5 and 77.6 ± 7.1 ( P < 0.0001), RVEDVI 86.4 ± 9.3 and 123.6 ± 11.9 ( P < 0.0001), and EF 27.6 ± 4.2 and 40.8 ± 5 ( P < 0.0001), respectively. One patient needed full decompression for bile ascites from unrecognized liver injury. Linea alba fasciotomy, as a first-line intervention before committing to full abdominal decompression in patients with SACS trauma, improved physiological variables without mortality Consideration for LAF as a bridge before full abdominal decompression needs further evaluation in patients with polytrauma SACS.

Effects of positive end-expiratory pressure on respiratory function and hemodynamics in patients with acute respiratory failure with and without intra-abdominal hypertension: a pilot study

INTRODUCTION

To investigate the effects of positive end-expiratory pressure (PEEP) on respiratory function and hemodynamics in patients with acute lung injury (ALI) or acute respiratory distress syndrome (ARDS) with normal intra-abdominal pressure (IAP < 12 mmHg) and with intra-abdominal hypertension (IAH, defined as IAP >or= 12 mmHg) during lung protective ventilation and a decremental PEEP, a prospective, observational clinical pilot study was performed.

METHODS

Twenty patients with ALI/ARDS with normal IAP or IAH treated in the surgical intensive care unit in a university hospital were studied. The mean IAP in patients with IAH and normal IAP was 16 +/- 3 mmHg and 8 +/- 3 mmHg, respectively (P < 0.001). At different PEEP levels (5, 10, 15, 20 cmH2O) we measured respiratory mechanics, partitioned into its lung and chest wall components, alveolar recruitment, gas-exchange, hemodynamics, extravascular lung water index (EVLWI) and intrathoracic blood volume index (ITBVI).

RESULTS

We found that ALI/ARDS patients with IAH, as compared to those with normal IAP, were characterized by: a) no differences in gas-exchange, respiratory mechanics, partitioned into its lung and chest wall components, as well as hemodynamics and EVLWI/ITBVI; b) decreased elastance of the respiratory system and the lung, but no differences in alveolar recruitment and oxygenation or hemodynamics, when PEEP was increased at 10 and 15cmH2O; c) at higher levels of PEEP, EVLWI was lower in ALI/ARDS patients with IAH as compared with those with normal IAP.

CONCLUSIONS

IAH, within the limits of IAP measured in the present study, does not affect interpretation of respiratory mechanics, alveolar recruitment and hemodynamics.

Usefulness of intra-abdominal pressure in a predominantly medical intensive care unit

BACKGROUND

The deleterious effects of elevated intra-abdominal pressure (IAP) have been known for more than a century. The proposed objectives were to measure changes in IAP and analyze increase-related factors and complications and whether high IAP and its persistence are related to complications and mortality in a predominantly medical intensive care unit.

METHODS

Over a 1-year period, we conducted a prospective cohort study in which IAP was measured using the bladder method. Hospitalization time, demographic variables, diagnosis on admission, APACHE II score, and clinical complications were recorded.

RESULTS

A total of 130 patients were studied. Overall mean IAP was 12.3 mm Hg (standard deviation [SD], 3.79; 95% confidence interval [CI], 11.7-13), and on the first day, 12.68 mm Hg (SD, 5.32; 95% CI, 11.8-13.6); maximum IAP was 16.4 mm Hg (SD, 4.6; 95% CI, 15.6-17.2). A positive correlation was found between IAP, APACHE (Acute Physiology And Chronic Health Evaluation) II, and age. Higher IAP values were independently associated with higher age, prolonged activated partial thromboplastin time, need for dialysis, and intolerance to enteral feeding. The value showing the best sensitivity and specificity in predicting mortality was persistence of IAP 20 mm Hg or greater for 4 days or more. The number of days with IAP 20 mm Hg or greater was a factor associated with a higher risk of death (odds ratio, 2.3). Patients who died showed a tendency to increased IAP.

CONCLUSION

In this study, a threshold IAP of 20 mm Hg and its permanence over time were the best predictive factors of complications and mortality. Among other relationships, we also observed that older patients had higher IAP. High IAP was a cause of intolerance to enteral nutrition.

Intra-abdominal hypertension: evolving concepts

This article focuses primarily on the recent literature on abdominal compartment syndrome (ACS) and the definitions and recommendations published by the World Society for the Abdominal Compartment Syndrome. The definitions regarding increased intra-abdominal pressure (IAP) are listed and are followed by an overview of the different mechanisms of organ dysfunction associated with intra-abdominal hypertension (IAH). Measurement techniques for IAP are discussed, as are recommendations for organ function support and options for treatment in patients who have IAH. ACS was first described in surgical patients who had abdominal trauma, bleeding, or infection; but recently, ACS has been described in patients who have other pathologies. This article intends to provide critical care physicians with a clear insight into the current state of knowledge regarding IAH and ACS.

Intra-abdominal pressure effects on porcine thoracic compliance in weightlessness: implications for physiologic tolerance of laparoscopic surgery in space

OBJECTIVE

Laparoscopic surgery (LS) is envisioned as an option for spaceflight, but requires intra-abdominal hypertension (IAH) to create the surgical domain. Prolonged weightlessness induces physiologic deconditioning that questions the ability of ill or injured astronauts to tolerate IAH. On earth, IAH results in marked ventilatory embarrassment. As there has been no previous study of physiologic changes related to LS in weightlessness, we studied anesthetized pigs in parabolic flight.

DESIGN

Parabolic flight research laboratory.

SUBJECTS

Five anesthetized Yorkshire pigs.

INTERVENTIONS

Subjects were transported from an animal care facility and secured aboard an aircraft capable of generating hypergravity and weightlessness. Mechanical ventilation was performed using pressure control and positive end-expiratory pressure at 15 and 2 cm H2O, respectively; rate 12 breaths/min. Three abdominal conditions were used during LS: insufflation to produce IAH, abdominal wall retraction (AWR), and no abdominal wall manipulation (baseline). During each parabola breath by breath-tidal volumes (Vt) were recorded by a transport ventilator (HT-50 Newport Medical).

MEASUREMENTS AND MAIN RESULTS

Least square means (LS-means) of weight corrected Vt (milliliter per kilogram) by gravity (g) and abdominal condition were determined using a mixed effects model for repeated measures analysis. Increasing gravity (g) consistently reduced Vt (p = 0.0011) as did insufflation (p < 0.0001). In 1g, Vt (LS-mean 13.7, 95% confidence interval [CI]: 12.4-15.0) was relatively unaffected by AWR (LS-mean 12.8, 95% CI: 11.5-14.00), but markedly decreased by IAH (LS-mean 10.00, 95% CI: 8.9-11.1), an effect accentuated in hypergravity (LS-mean 8.1, 95% CI: 6.4-9.8). In weightlessness, Vt reduction during insufflation was near obviated (LS-mean 12.3, 95% CI: 10.6-14.1), and AWR regularly but inconsistently increased the Vt above 1g baseline (LS-mean 13.7, 95% CI: 11.7-15.8).

CONCLUSIONS

Weightlessness protects against thoracic compliance changes that are inherent in IAH during induced pneumoperitoneum in gravity. The technique-related physiologic cost of performing LS in space deconditioned astronauts should be incorporated into design concepts for space surgery systems.

What is the role of the abdominal perfusion pressure for subclinical hepatic dysfunction in laparoscopic cholecystectomy?

BACKGROUND

Subclinical hepatic dysfunction after laparoscopic cholecystectomy (LC) has been described in the literature. However, this alteration is not encountered in all patients. In order to address this situation, a prospective study was conducted to investigate the effect of abdominal perfusion pressure (APP) on liver function tests after LC performed under constant intra-abdominal pressure (IAP).

PATIENTS AND METHODS

Of 78 patients who underwent LC between May 2007 and October 2007, 40 patients were eligible for the study. In all the patients, six parameters of liver function (aspartate aminotransferase, alanine aminotransferase, direct bilirubin, indirect bilirubin, alkaline phosphatase, and gamma-glutamyltransferase) were assessed before and 24 hours after surgery. Patients who showed more than a 100% increase in at least one parameter (group 1) were compared to those who did not (group 2) regarding age, sex, body weight, body height, operation time, pneumoperitoneum time, IAP, preoperative, and intraoperative APP.

RESULTS

Of the patients, 37.5% showed more than a 100% increase in at least one parameter of liver function. No significant difference was found between the two groups with regard to age, sex, body weight, body height, operation time, pneumoperitoneum time, and IAP. There were significant increase in AST and ALT at 24 hours postoperatively in group 1, as compared with group 2 (P = 0.000, P = 0.001). In comparison of preoperative APP with intraoperative APP values, group 1 showed a statistically significant decrease (P = 0.000), while no difference was found in group 2.

CONCLUSION

Subclinical hepatic dysfunction after LC could mostly be attributed to the negative effects of the pneumoperitoneum on hepatic blood flow. For the evaluation of hepatic hypoperfusion, APP may be a new criterion as a determinant of interaction with mean arterial pressure (MAP) and IAP.