Tuesday, April 7, 2015

Needle that belly!

An infant female with no significant history presents to your trauma bay after reported accidental blunt trauma to the abdomen, the patient arrives from a referral hospital where plain films demonstrated free air. On arrival the patient show signs of hemodynamic instability and an elevated lactate. The patient was decompressed with "needle peritoneumostomy" prior to going to the OR for exploration. 

Clinical Question:

Can “tension pneumoperitoneum” cause hemodynamic instability?

Literature Review:

The presence of "free air" in the peritoneum is often diagnostically significant; however, the gas itself is rarely of clinical importance. An exception to this rule is in the case of a tension pneumoperitoneum. Tension pneumoperitoneum (TPP), also known as hyperacute abdominal
Example of pneumoperitoneum & football sign
compartment syndrome [1], or abdominal tamponade [2], is a rare, but potentially deadly event. Similar to tension pneumothorax, the underlying mechanism is a tissue flap that acts as a one-way valve for air release, resulting in a progressive increase in intra-abdominal pressure. The increasing peritoneal pressures may rapidly lead to respiratory compromise due to diaphragmatic elevation and a drop in cardiac output resulting from decreased venous return or aortic outflow due to occlusion. [3] This can progress to cardiovascular collapse and respiratory failure and eventually death. [2]

In one of the earliest reported cases in 1913, tension pneumoperitoneum was theorized to be a consequence of gas forming bacteria in the abdominal cavity. [4] Now it is known that tension pneumoperitoneum is usually a consequence of hollow viscus perforation, post-operative complications, positive pressure ventilation or other insulflation-dependent procedures (eg, colonoscopy, endoscopy, cystoscopy or air enema). There has even been reported cases from CPR. [9,10] However, there are few published case reports of TPP as a result of blunt force trauma. [3,6]

Signs and symptoms of TPP include abdominal distension and fullness. The additional presence of a tympanitic, rigid abdomen, hypotension, dyspnea, and jugular vein congestion can be considered as signs of TPP, requiring immediate management.

The diagnosis of tension pneumoperitneum should be based physical exam and supported by imaging of the abdomen. Plain films of the abdomen show large amounts of intraperitoneal air. Lateral supine and left lateral decubitus films show the air best. Elevation of the diaphragm or medial displacement of the liver, called the “saddlebag sign” is suggestive of tension physiology.[1] The viscera may appear more distinct as they are outlined by the air tissue interface as in the double-wall sign (the visualization of the outer wall of bowel loops caused by the presence of extraluminal and intraluminal gas). Another radiographic sign of a large pneumoperitoneum is football sign - the intraperitoneal air outlines the abdominal cavity and the falciform ligament appears like the laces of a football.

With this said, plain films of the abdomen are rarely obtained in the setting of trauma. If hemodynamically stable, the patient is imaged using computed tomography (CT scan) which will show posterior liver compression by superiorly located free air. However, because CT scanning is contraindicated in the hemodynamically unstable patient, the diagnosis may have to rest on the clinical presentation and/or portable plain films. It can be confirmed by needle decompression or paracentesis with a rush of air and improvement of hemodynamic stability. [7]
Treatment of tension pneumoperitoneum depends on the stability of the patient. If the patient is acutely unstable with labile blood pressures and signs of shock, treatment is emergent needle decompression using a 14g angiocatheter. There are no large trials that recommend a specific location based on success and/or safety rates. However, several small case series suggest using the same sites for decompression: two centimeters below the umbilicus in the midline (through the linea alba) or five centimetres superior and medial to the anterior superior iliac spines on either side. [8]. If the patient is stable, a paracentesis catheter/drain can be placed. The definitive treatment is to determine what initially caused the air accumulation, which may necessitate an exploratory laparotomy. It should be noted that a nasogastric tube turned to suction is unlikely to evacuate the pneumoperitoneum due to the ball and valve mechanism that created it initially. [3]

Take-home Points: 
-Pathophysiology and treatment is similarly to pneumothorax, it can lead to cardiovascular collapse, respiratory failure, and eventually death if untreated. Unstable patients should be recognized on exam, however x-ray and CT have utility based on stability. Decompression is the treatment and can be performed with an angiocath placed two centimeters below the umbilicus in the midline. 

[1] Lin B, Tension Pneumoperitoneum. The Journal of Emergency Medicine, Vol. 38, No. 1, pp. 57–59, 2010.
[2] Khan ZA. Conservative management of tension pneumoperitoneum. Ann R Coll Surg Engl. 2002 May;84(3):164-5.
[3] Ogle JW Tension Pneumoperitoneum after Blunt Trauma. The Journal of Trauma: Injury, Infection, and Critical Care. 1996 Nove; 41(5): 909-911.
[4] Falkenburg C. Ein Fall von Gasansammlung in der freien Bauch-Hohle. Dtsch Z Chir 1913;124: 130-6.
[5] Olinde A, Carpenter D, Maher J. Tension pneumo-peritoneum. Arch Surg 1983;118:1347-50.

[6] Ferrera PCChan L. Tension pneumoperitoneum caused by blunt trauma. Am J Emerg Med. 1999 Jul;17(4):351-3.
[7] Yakobi-Shvili RCheng D. Tension pneumoperitoneum--a complication of colonoscopy: recognition and treatment in the emergency department. J Emerg Med. 2002 May;22(4):419-20.
[8] Fu KIshikawa TYamamoto TKaji Y. Paracentesis for successful treatment of tension pneumoperitoneum related to endoscopic submucosal dissection. Endoscopy. 2009;41 Suppl 2:E245.
[9] Williams DTManoochehri PKim HT. Tension pneumoperitoneum. Emerg Med J. 2014 Nov;31(11):943.
[10] Mills SAPaulson DScott SMSethi G. Tension pneumoperitoneum and gastric rupture following cardiopulmonary resuscitation. Ann Emerg Med. 1983 Feb;12(2):94-5.
Submitted by Decompression Danny Kolinsky, PGY-2
Edited by Louis Jamtgaard, PGY-3. @Lgaard
Faculty review by Rebecca Bavolek

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