What is Abdominal Compartment Syndrome?
Compartment syndrome is a condition where increased pressure builds up in a small space within the body, leading to reduced blood flow, cell damage, and in severe cases, organ failure. This happens in areas bounded by muscles and tissues that limit space for expansion as pressure rises. The focus is often on Abdominal Compartment Syndrome (ACS), evident among severely ill patients and can result in multiple organ failure.
In 2004, the World Society of Abdominal Compartment Syndrome (WSACS) was established to standardize ACS definitions, guidelines for evaluations, and treatments, as it’s often underdiagnosed. The steady-state pressure within the abdomen, termed Intra-Abdominal Pressure (IAP), plays a role here. Normally, the IAP is between 0 to 5 mm Hg in adults, but in severely ill patients, it can increase to 5 to 7 mm Hg. Other factors such as body shape and chronic health conditions may also impact IAP, requiring careful consideration during ACS assessment. An elevated IAP can cause Intra-Abdominal Hypertension (IAH), defined as IAP ≥ 12 mm Hg, but this is not synonymous with ACS. ACS can occur when the IAP exceeds 20 mm Hg. However, organ dysfunction can start even before this threshold is reached.
Failure to promptly detect and manage ACS can worsen outcomes and is recognized as a predictor of death. It’s crucial to keep a high level of suspicion, use standardized monitoring, and implement medical management in treating severely ill patients, particularly those with major fluid changes. It applies especially to patients with tight and swollen abdomens paired with instability in their clinical conditions. The abdomen is one of several enclosed spaces in the body – all of which are connected to multiple organs. Any increase in IAP can affect nearby areas, and in extreme cases, cause dysfunction in multiple organs. Timely identification of ACS causes and early interventions can reverse organ dysfunction.
What Causes Abdominal Compartment Syndrome?
The flexibility of your belly area, or abdominal compliance, mainly depends on the elasticity of your stomach wall and diaphragm. If the pressure inside your abdomen increases, it can disrupt the blood vessels function, including reducing the blood flow and damaging the cells that line the blood vessels. Increased abdominal pressure can also lead to greater release of a hormone that affects fluid balance in the body, which in turn increases fluid retention.
The World Society of the Abdominal Compartment Syndrome (WSACS) has categorized increased intra-abdominal pressure into four levels, known as grades, based on the pressure measurement in millimeters of mercury, abbreviated as mm Hg:
- Grade I: 12-15 mm Hg
- Grade II: 16-20 mm Hg
- Grade III: 21-25 mm Hg
- Grade IV: Higher than 25 mm Hg
If there’s high pressure in the abdomen and organs are not functioning correctly, it could suggest Abdominal Compartment Syndrome (ACS). Surgeries such as liver transplantation, large-scale injury surgery, repair of bulging stomach arteries, and large stomach hernia repairs carry a higher risk of increasing this pressure.
However, not only surgery but other factors as well could cause ACS. These can be further classified into primary or secondary causes. Primary ones include injuries, internal bleeding, ruptured stomach arteries, scars from previous operations or health conditions, blockages in the intestine, tumor formation, enclosed blood clot. Secondary causes arise from conditions not inside the stomach, like pregnancy, fluid accumulation in the stomach, temporary blockages in the intestine, stomach infections, large amounts of fluid intake.
Chronic conditions like pregnancy, liver conditions, abdominal malignancies, and kidney treatment can keep this pressure perpetually high. Individuals with a higher body mass index can expect to have a higher baseline belly pressure roughly between 9-14 mm Hg due to fatty tissue.
Causes of High Abdominal Pressure (IAH) and ACS could be grouped into various categories:
- Reduced belly flexibility: abdominal surgery, stomach scars, major trauma, major burns, mechanical ventilation, obesity.
- Increased volume inside the intestines: slow stomach emptying, stomach bloating, intestinal blockage, constipation, toxic large colon, twisted intestine.
- Increased volume outside the intestines within the belly: internal bleeding, air in the stomach, severe pancreatitis, liver failure with fluid accumulation in abdomen, tumors, belly infections, too much gas during a laparoscopy, kidney dialysis.
- Liquid leakage/Fluid resuscitation: severe surgery, bacterial infection in the blood, system-wide inflammation, blood disorders, infections, lots of fluid, blood transfusions.
Risk Factors and Frequency for Abdominal Compartment Syndrome
ACS, a serious condition that can affect people in intensive care units (ICUs), happens when there’s too much pressure in the abdomen. Relevant studies have shown that ACS can develop swiftly and potentially turn life-threatening. In one study, it was found that 34% of critical patients had high abdominal pressure on their first day in the ICU, and this rose to nearly half (48.9%) within two weeks. Notably, an increase in abdominal pressure was linked to a higher chance of passing away. In another study involving a mixed group of ICU patients, about a third (32%) had high abdominal pressure, while a smaller group (4%) developed ACS.
- ACS can develop in all ICU and critically ill patients.
- In one study, 34% of patients had high abdominal pressure on the day they were admitted to the ICU.
- This figure increased to 48.9% within two weeks.
- The development of high abdominal pressure was associated with a higher death rate.
- In another study of mixed ICU patients, 32% had high abdominal pressure and 4% developed ACS.
Signs and Symptoms of Abdominal Compartment Syndrome
The Abdominal Compartment Syndrome (ACS) is often seen in critically ill patients, particularly in Intensive Care Units (ICU) rather than emergency departments. It’s important to note that physical checks aren’t reliable for diagnosing ACS, even when performed by seasoned medical professionals. Because of this, objective measurements are crucial for any patient with risk factors for Intra-Abdominal Hypertension (IAH).
Patients with abdominal injuries, those who have received large amounts of fluids as part of their treatment, or have had significant abdominal surgery should be closely watched for ACS. Diagnosing ACS becomes difficult in ICU patients, as they may have numerous other organ failures outside of the abdomen. Additionally, certain patients may be on a ventilator, and hence unable to express their symptoms. Therefore, meticulous monitoring of intra-abdominal pressure (IAP), reviewing patient medical histories, and careful examination of the overall health situation are critical for diagnosing ACS properly.
Testing for Abdominal Compartment Syndrome
While not standard for diagnosing Abdominal Compartment Syndrome (ACS), medical imaging can show early signs of a condition called Intra-abdominal Hypertension (IAH) which could lead to ACS. These signs include a certain ratio of abdomen width to height, thickening of the intestine wall, raised diaphragm, thinning of a large vein called the vena cava, and a significant amount of fluid build-up in the abdomen.
To definitely confirm ACS, doctors measure the pressure inside the abdomen (IAP). Whenever there’s a risk of IAH, it’s crucial to check the IAP. There are both direct and indirect methods to measure IAP. Direct methods involve using pressure sensors during laparoscopic surgery or intraperitoneal catheters. Although direct methods are highly accurate, they are invasive.
The most common method of measuring IAP is indirectly through bladder catheter pressures, which is more practical due to its wide availability and less invasive nature. The process includes cleaning the Foley catheter, connecting it to a device known as a 3-way stopcock, adjusting it to match the body’s mid-side level, then injecting sterile saline into the bladder. The measurements are taken while the patient lies flat and at the end of the breath cycle.
In healthy individuals, bladder pressures below 5 mm Hg are normal. Post-abdominal surgery and in obese patients, pressures between 10 to 15 mm Hg can be anticipated. Bladder pressures over 25 mm Hg may indicate ACS and should be examined clinically. If ACS is a potential risk, pressure measurements need to be taken every 6 hours to monitor any increase in IAH.
However, certain conditions like bladder trauma, enlarging prostate, neurogenic bladder, and pelvic hematoma can interfere with the bladder pressure measurement. Other factors such as pelvic fractures, bladder hematoma, and attachments in the abdominal cavity may also result in inaccurate readings.
In cases where bladder measurements are not possible, other methods could be considered including inserting a central line to measure the pressure in the vena cava, manometry through a drain or measuring pressure in the stomach using a nasogastric tube. However, these methods are not validated or commonly used.
Treatment Options for Abdominal Compartment Syndrome
The choice and timing of treatment for high intra-abdominal pressure (IAP) depends on the cause, the length of the condition, and the level of organ impairment. Not every patient with Abdominal Compartment Syndrome (ACS) needs to go to surgery straight away. Some non-surgical methods can lower the amount of volume in the abdomen and eventually improve IAP.
If needed, the volume inside the intestines can be decreased with the help of a nasogastric tube (a tube that goes through the nose into the stomach), a rectal tube, or with endoscopic decompression. Volume outside the intestines, in cases of fluid retention or a blood clot, can be lessened with percutaneous drainage. This method involves making a small hole and draining the excess fluid. Other ways to improve flexibility of the abdominal wall include suitable sedation, muscle relaxation, or removal of tight bandages.
The World Society of the Abdominal Compartment Syndrome (WSACS) also recommends managing fluid intake, using hypertonic products or colloids for resuscitation, considering hemodialysis or ultrafiltration, and a targeted resuscitation. However, these methods are based on low-quality evidence and should be considered carefully.
Percutaneous catheter drainage can be a good choice for ACS that’s caused by a large amount of fluid outside the intestines. This treatment is much less invasive than a surgical laparotomy and can be used as a temporary measure if immediate surgical decompression is not an option. Large volumes outside the intestines are usually caused by excessive air, fluid, or blood in the abdominal cavity.
If non-surgical methods do not result in improved IAH and further organ damage is seen, emergency surgery (laparotomy) might be considered. This could rapidly improve any organ dysfunction as it’s usually a direct result of restricted blood flow or mechanical obstruction. The abdomen may be left open temporarily after surgery, and the open wound is often covered with a negative pressure dressing system. This helps minimize the risks of infection and fistulas, decreases fluid loss, and prevents retraction of the fascia (connective tissue). Once the patient’s condition improves, the wound can be closed with mesh or primary closure techniques.
However, some of these treatments may not be possible in all hospitals due to limited resources. Surgical decompression is considered the ultimate treatment for ACS, but it can also have many complications. These include fistula formation (abnormal connections between organs), protein loss due to drainage of abdominal fluid, retraction of the abdominal wall resulting in a ventral hernia (bulge through an opening in the muscles), and wound infection. Plus, up to 20% of surgeries result in recurrent ACS, either because the underlying cause continues or the IAP wasn’t reduced enough.
There’s no agreement on when surgery should be performed for ACS. Having surgery too soon can put unnecessary stress on the patient. Therefore, the general consensus within the medical community is to consider surgery only when multiple conservative treatments haven’t improved the patient’s condition.
What else can Abdominal Compartment Syndrome be?
Doctors diagnosing acute coronary syndrome (ACS) might also consider the following conditions, which can display similar symptoms:
- Intestinal issues due to poor blood supply (mesenteric ischemia)
- A serious condition where a large blood vessel wall in the abdomen weakens and ruptures (ruptured abdominal aortic aneurysm)
- A life-threatening enlargement and inflammation of the colon (toxic megacolon)
- Painful inflammation of the appendix (acute appendicitis)
- Inflammation and swelling of sacs or pouches in the wall of the colon (acute diverticulitis)
These conditions need to be taken into account while performing tests and evaluations for an accurate diagnosis of the patient’s symptoms.
What to expect with Abdominal Compartment Syndrome
Abdominal compartment syndrome, if not treated promptly, can be extremely dangerous and even deadly. Late treatment often leads to high mortality rates. The severity of intra-abdominal hypertension (IAH), which is a condition where the pressure in the abdomen is too high, is linked to worse health outcomes and can predict whether a person will survive the condition.
Many studies have shown that this condition can cause failure of multiple organs in the body, which can delay recovery for several weeks or months, even with treatment. Patients often need to be on a mechanical ventilation machine for a long period, require dialysis, and usually have longer hospital stays.
Possible Complications When Diagnosed with Abdominal Compartment Syndrome
Complications of ACS (Acute Compartment Syndrome) can be severe and varied. They include:
- Kidney failure
- Bowel suffering from inadequate blood supply
- Breathing distress or failure
- Increased pressure within the skull
- Heart failure
- Potential for death
Preventing Abdominal Compartment Syndrome
The key to preventing the development of ACS (Abdominal Compartment Syndrome) primarily involves monitoring the abdominal pressure in patients who are at risk, particularly those in intensive care units (ICU). There are also other methods to reduce the risk of increased abdominal pressure. Using IV fluids and blood products wisely, making sure to avoid excessive fluid accumulation, employing low-strength breaths when using a ventilator, utilizing medications that stimulate bowel movements to prevent blockages or constipation, and reducing tube feedings can all help prevent ACS.