CONTENTS
- Rapid Reference 🚀
- Causes
- Epidemiology
- Physiological relationships between various compartments
- Physiology & manifestations
- Diagnosis
- Treatment
- Podcast
- Questions & discussion
- Pitfalls
treatment of abdominal compartment syndrome ✅
hemodynamics (more)
- Target MAP > (60 mm + abdominal compartment pressure).
- Don’t give additional fluid.
- Consider diuresis/dialysis, if possible.
decompress the abdomen (more)
- Ascites: Drain (indwelling catheter might be ideal approach).
- NPO, Gastric tube to suction.
- Decompress the colon (e.g., suppositories, neostigmine for megacolon).
- Fascial release is definitive treatment, but most invasive. Reserve this for failure of other measures.
decompress the thorax (more)
- Large pleural effusion: consider drainage.
- Avoid intubation if able.
- Reduce airway pressures as able (e.g., target low PEEP & plateau pressures).
sedation & paralysis (if intubated) (more)
- Start with analgesia/sedation to target a passive state on ventilator.
- Paralysis may be used as a short-term therapy.
The causes of abdominal compartment syndrome are diverse, with many patients having several. In many cases, the cause may be obvious based on the clinical scenario. In other situations, CT scan may be helpful to clarify the cause of abdominal distension.
primary abdominal compartment syndrome (intra-abdominal processes)
- Severe pancreatitis.
- Trauma, abdominal surgery.
- Ascites.
- Hemorrhage (retroperitoneal, intraperitoneal, or rectus sheath).
- Dilated viscera:
- Severe ileus or obstruction.
- Colonic pseudo-obstruction.
- Toxic megacolon.
secondary abdominal compartment syndrome (extra-abdominal causes)
- Major burn injuries.
- Septic shock.
- Hemorrhagic shock (especially with excess crystalloid resuscitation).
- Large-volume fluid resuscitation.
exacerbating factors
- Elevated intrathoracic pressure (e.g., ARDS patients on high PEEP).
- Prone positioning.
- Abdominal wall restriction (e.g., circumferential burns, obesity, tight abdominal wall closure after surgery).
- Pregnancy.(32004192)
abdominal compartment syndrome is common
- Medical ICU:
- Surgical ICU: higher rates than medical ICU.
pressure transduction between different compartments
- Although we often think only about the abdominal compartment, there are three compartments as shown below.
- The diaphragm is a thin strip of muscle, across which pressure can be transduced in either direction. Thus, there is considerable pressure transmission between the thoracic and abdominal compartments.
- Elevated intrathoracic pressure leads to elevated central venous pressure, which ultimately increases the intracranial pressure (ICP).
“abdominal compartment syndrome” is a misnomer
- Traditionally, the literature has used the following terminology:
- Abdominal compartment syndrome refers to elevated intra-abdominal pressures causing organ failure.
- Polycompartment syndrome refers to elevation of multiple compartment pressures, with organ failure.
- However, due to pressure transduction between compartments, it's impossible to have truly isolated abdominal compartment syndrome. For example, elevated peak airway pressures are a classic component of “abdominal compartment syndrome.” Thus, to some extent, all patients with abdominal compartment syndrome actually have a polycompartment syndrome.
- Appreciating the polycompartment nature of “abdominal compartment syndrome” has important clinical implications, for example:
- Reduction of intrathoracic pressure may be beneficial for patients with intra-abdominal compartment syndrome.
- Patients with abdominal compartment syndrome are at increased risk of elevated intracranial pressure.(11445709)
general principles
- Abdominal compartment syndrome can cause failure of numerous (heart, lungs, kidneys, brain). In severe cases, this promotes a vicious spiral of multiorgan failure (e.g., when failure of the heart causes worsening failure of the kidneys). Indeed, it's likely that abdominal compartment syndrome is an occult driver of multiorgan failure among many critically ill patients.
- The initial manifestations of abdominal compartment syndrome will vary depending on the patient's underlying physiology.
- A patient with tenuous renal function could manifest with renal failure.
- A patient with severe, chronic COPD might present with respiratory distress.
cardiovascular
- Physiology:
- Compression of the inferior vena cava reduces preload.
- Direct cardiac compression causes reduced cardiac filling and decreased contractility (including reduced compliance of the right ventricle).(30454823)
- Filling pressures (e.g., central venous pressure) are elevated, but this doesn't reflect effective cardiac filling (because the pressure gradient between the vena cava and right ventricle is reduced).
- Peripheral vascular resistance is elevated to to renal compression (which stimulates the renin-angiotensin-aldosterone system). This causes a maintained systolic blood pressure (despite a reduction in cardiac output).(32004192)
- Mesenteric ischemia causes bacterial translocation into the bloodstream, which may cause systemic vasodilation and hypotension (late in the evolution of multiorgan failure).
- Clinical manifestations:
- Abdominal compartment syndrome may confound many approaches to hemodynamic optimization.
- The systemic blood pressure is often preserved initially, until multi-organ failure develops.
respiratory
- Physiology
- Pressure on the diaphragm reduces thoracic compliance (e.g., an intra-abdominal pressure of 16 cm may reduce the pulmonary compliance by 50%).(30454823)
- Atelectasis may occur due to compression of the lung bases, promoting hypoxemia and hypercapnia.
- Clinical manifestations
- A non-intubated patient may experience increased work of breathing.
- For an intubated patient, this may manifest as increased airway pressures on the ventilator.
renal
- Physiology
- Renal failure with reduced urine output is often the first sign of abdominal compartment syndrome (often occurring when intra-abdominal pressure rises >15 cm).(32004192)
- Increased pressure may compress the kidney directly and also cause renal congestion (due to elevation of venal vein pressure causing impaired drainage of blood out of the kidney).
- Brain hypoperfusion may increase cerebral vasopressin secretion, which also serves to reduce urine output.(33480617)
- Clinical manifestations
- Oliguric acute renal failure is generally one of the earliest manifestations of abdominal compartment syndrome.
brain: increased intracranial pressure
- Physiology
- Increased abdominal pressures will translate into increased intrathoracic pressures and increased central venous pressures. This can actually cause elevated intracranial pressure.
- Clinical manifestations
- May cause delirium, stupor, or coma.
physical examination
- Abdominal pressures can be elevated despite finding a soft abdomen. Palpation is only ~50% sensitive for abdominal compartment syndrome.(31524716)
- Examination demonstrating tense abdomen is ~80% specific for abdominal compartment syndrome.(12297912)
abdominal pressure measurement using a Foley catheter
- Technical details:
- Patient should be fully supine, intubated, and breathing passively on the ventilator (e.g., not coughing or bucking ventilator).
- Measured at end-expiration.
- Limitations on abdominal pressure:
- (1) Pressures may vary across individuals (with obese patients having higher baseline pressure values).
- (2) As with all physiological phenomena, pressure gradients are more important than absolute pressure values. Consequently, the intra-abdominal pressure value in isolation is inadequate to define abdominal compartment syndrome.
- (3) Pressure measurements may be inaccurate in the context of pelvic pathology (e.g., hematoma directly compressing the bladder).
- (4) Interpretation among patients who are not intubated and breathing passively on mechanical ventilation is challenging. If analgesia/sedation causes a normalization of the intra-abdominal pressure, this makes abdominal compartment syndrome unlikely.(32204721)
- Some rough benchmark numbers for intra-abdominal pressure:
- 2-7 mm Hg: Normal for a non-obese person.
- >12 mm Hg: Defined as intra-abdominal hypertension.
- >15-20 mm Hg: Can cause organ failure.
- >20 mm Hg: Cutoff used to define abdominal compartment syndrome.
- >25-30 mm Hg: Usually causes organ failure, may require emergent decompression.
diagnostic criteria for abdominal compartment syndrome
- Diagnosis requires two components:
- (1) Sustained intra-abdominal pressure >20 mm.
- (2) Organ failure attributable to elevated intra-abdominal pressure.
- This diagnosis requires clinical judgement, since critically ill patients invariably have other causes of organ failure.
- Sorting out whether organ failure is caused by abdominal compartment syndrome versus other causes can be murky and subjective.
- 💡 The kidneys are one of the most sensitive organs to increased abdominal pressure. If the urine output is adequate, it's considerably less likely that the patient has abdominal compartment syndrome.
There are many treatments of abdominal compartment syndrome other than surgical decompression of the abdomen. Thus, the inability to perform surgery should not lead to a sense of cynicism about the treatment of this disorder.
defend the abdominal perfusion pressure
Abdominal Perfusion Pressure = MAP – (Abdominal Compartment Pressure)
- Abdominal perfusion pressure is the pressure gradient between the MAP and the abdominal compartment. This is the pressure that drives perfusion of all intra-abdominal organs (e.g., the kidney).
- It is probably best to maintain an abdominal perfusion pressure >60mm.(12297912) Abdominal perfusion pressure <60 mm predicts the need for surgical decompression.(30454823) Consequently, the target MAP might be 60 mm plus the abdominal compartment syndrome, as shown below.
- Hemodynamic interventions may be tailored to the particular patient. This will generally require vasopressors, because additional crystalloid may merely aggravate abdominal tissue edema.(12799335)
Target MAP > (60 mm + Abdominal Compartment Pressure)
volume removal if possible
- Theoretically, volume removal is beneficial:
- In many patients, compartment syndrome may be promoted by volume overload.
- Efforts to remove volume (e.g., diuresis or dialysis) may be helpful.(25421925)
- Unfortunately, in established abdominal compartment syndrome, the patient is often intravascularly volume depleted (despite tissue edema). This may make it difficult or impossible to remove fluid without worsening hemodynamics.
- A more realistic fluid target might be to achieve a net even fluid balance.
- Cautions:
- (1) Abdominal compartment syndrome may compress the inferior vena cava (IVC), making it look empty!
- (2) Avoid fluid administration. This may help temporarily, but fluid will often rapidly transudate into the tissues – which worsens swelling and increases intra-abdominal pressure (generating a futile cycle, as shown below).
drainage of ascites
- If a significant volume of ascites is present, this should be drained.
- An indwelling percutaneous drainage catheter may remove this more completely than intermittent therapeutic paracentesis.(21903735)
removal of gut contents
- Nasogastric or orogastric tube suction may be used to manage gastric distention.
- Colonic distention may be managed with some combination of:
- Suppositories.
- IV neostigmine.📖
- Rectal tube drainage.
- Colonoscopy with decompression.
surgical decompression
- This is often the treatment of last resort, if less invasive measures fail to be effective.
- Release of the abdominal fascia is definitive treatment, albeit invasive.
- Following fascial release, patients may experience a severe ischemia-reperfusion event, requiring aggressive hemodynamic support.(32204721)
- Postoperatively, patients will be left with an open abdomen. Ideally this may be closed after 1-2 weeks following resolution of primary process.
measures to reduce intrathoracic pressure
- Reduction of PEEP and plateau pressure on the ventilator may decrease intra-abdominal pressure.
- Permissive hypercapnia may allow for liberalization of ventilator settings.
- If a large pleural effusion is present, drainage could be beneficial.
beware of intubation
- Intubation converts the thorax from a negative-pressure system to a positive-pressure system. This may acutely increase abdominal pressures, precipitating multiorgan failure with hemodynamic collapse.
- 💡 Abdominal compartment syndrome is one cause of post-intubation cardiac arrest.
agitation (e.g. bucking the ventilator)
- This will increase intra-abdominal pressures.
- Adequate analgesia and sedation may be helpful, perhaps to a slightly deeper level than the average ICU patient.
paralysis
- Paralysis may have various effects on intra-abdominal pressure:
- (1) Relaxation of muscles in the abdominal wall will improve the abdominal compliance, thereby reducing the intra-abdominal pressure.
- (2) Some patients are performing a substantial amount of the work of breathing, which tends to decrease their intrathoracic pressures. In this situation, paralysis will cause a transition to purely passive, positive-pressure ventilation – increasing their intrathoracic pressure, and thereby increasing the intra-abdominal pressure.(32204721)
- Short-term paralysis may be trialed, but this doesn't appear to cause persistent improvement. Paralysis may be used temporarily as a bridge to another intervention (e.g., laparotomy).(27016163)
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- Adopting the mindset that the only treatment for abdominal compartment syndrome is laparotomy. This leads practitioners to ignore the diagnosis (“well, surgery isn't going to operate on them anyway…”). However, there are numerous non-operative therapies which may be quite effective.
- Failure to consider abdominal compartment syndrome (this is a common phenomenon in all types of critically ill patients – not just surgical patients).
- Over-interpretation of bladder pressure obtained in patients who aren't supine and breathing passively.
- Abdominal compartment syndrome compresses the inferior vena cava (IVC), making it look empty. This may lead to erroneous decisions regarding fluid administration.
- Avoid intubation of patients with borderline abdominal compartment syndrome if possible (pressurization of the thorax may worsen intra-abdominal pressure).
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- = Link to online calculator.
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- = Link to IBCC section about a drug.
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Going further
- IBCC chapter on pancreatitis.
- Killer resuscitation: Abdominal hypertension as an occult driver of multiorgan failure (PulmCrit)
- Abdominal Compartment Syndrome (Chris Nickson, LITFL)
- Abdominal Compartment Syndrome (Shaun Harty andJessica Baez, Taming the SRU)
- Abdominal Compartment Syndrome (WikiEM)
- Abdominal Compartment Syndrome: When should it be on your differential? (Erica Simon, emDocs)
- Epic lecture by Thomas Scalea on poly-compartment syndrome:
References
- 11038078 Cheatham ML, White MW, Sagraves SG, Johnson JL, Block EF. Abdominal perfusion pressure: a superior parameter in the assessment of intra-abdominal hypertension. J Trauma. 2000 Oct;49(4):621-6; discussion 626-7. doi: 10.1097/00005373-200010000-00008 [PubMed]
- 12297912 Sugrue M, Bauman A, Jones F, Bishop G, Flabouris A, Parr M, Stewart A, Hillman K, Deane SA. Clinical examination is an inaccurate predictor of intra-abdominal pressure. World J Surg. 2002 Dec;26(12):1428-31. doi: 10.1007/s00268-002-6411-8 [PubMed]
- 12799335 Balogh Z, McKinley BA, Cocanour CS, Kozar RA, Valdivia A, Sailors RM, Moore FA. Supranormal trauma resuscitation causes more cases of abdominal compartment syndrome. Arch Surg. 2003 Jun;138(6):637-42; discussion 642-3. doi: 10.1001/archsurg.138.6.637 [PubMed]
- 17895487 Daugherty EL, Hongyan Liang, Taichman D, Hansen-Flaschen J, Fuchs BD. Abdominal compartment syndrome is common in medical intensive care unit patients receiving large-volume resuscitation. J Intensive Care Med. 2007 Sep-Oct;22(5):294-9. doi: 10.1177/0885066607305247 [PubMed]
- 21903735 Cheatham ML, Safcsak K. Percutaneous catheter decompression in the treatment of elevated intra-abdominal pressure. Chest. 2011 Dec;140(6):1428-1435. doi: 10.1378/chest.10-2789 [PubMed]
- 24280691 Ortiz-Diaz E, Lan CK. Intra-abdominal hypertension in medical critically ill patients: a narrative review. Shock. 2014 Mar;41(3):175-80. doi: 10.1097/SHK.0000000000000100 [PubMed]
- 25421925 Regli A, De Keulenaer B, De Laet I, Roberts D, Dabrowski W, Malbrain ML. Fluid therapy and perfusional considerations during resuscitation in critically ill patients with intra-abdominal hypertension. Anaesthesiol Intensive Ther. 2015;47(1):45-53. doi: 10.5603/AIT.a2014.0067 [PubMed]
- 26309180 Anvari E, Nantsupawat N, Gard R, Raj R, Nugent K. Bladder Pressure Measurements in Patients Admitted to a Medical Intensive Care Unit. Am J Med Sci. 2015 Sep;350(3):181-5. doi: 10.1097/MAJ.0000000000000543 [PubMed]
- 27016163 Maluso P, Olson J, Sarani B. Abdominal Compartment Hypertension and Abdominal Compartment Syndrome. Crit Care Clin. 2016 Apr;32(2):213-22. doi: 10.1016/j.ccc.2015.12.001 [PubMed]
- 30454823 Sosa G, Gandham N, Landeras V, Calimag AP, Lerma E. Abdominal compartment syndrome. Dis Mon. 2019 Jan;65(1):5-19. doi: 10.1016/j.disamonth.2018.04.003 [PubMed]
- 31524716 Pereira BM. Abdominal compartment syndrome and intra-abdominal hypertension. Curr Opin Crit Care. 2019 Dec;25(6):688-696. doi: 10.1097/MCC.0000000000000665 [PubMed]
- 32004192 Allen R, Sarani B. Evaluation and management of intra-abdominal hypertension. Curr Opin Crit Care. 2020 Apr;26(2):192-196. doi: 10.1097/MCC.0000000000000701 [PubMed]
- 32204721 De Laet IE, Malbrain MLNG, De Waele JJ. A Clinician's Guide to Management of Intra-abdominal Hypertension and Abdominal Compartment Syndrome in Critically Ill Patients. Crit Care. 2020 Mar 24;24(1):97. doi: 10.1186/s13054-020-2782-1 [PubMed]
- 33480617 Kimball EJ. Intra-abdominal hypertension and abdominal compartment syndrome: a current review. Curr Opin Crit Care. 2021 Apr 1;27(2):164-168. doi: 10.1097/MCC.0000000000000797 [PubMed]