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83-Year-Old Man With Chronic Kidney Disease, Fluid Overload, and Coronary Artery Disease Develops Altered Mental Status FREE TO VIEW

Brett C. Bade, MD; Sean P. Callahan, MD; Jean Paul Higuero, MD; Nicholas Pastis, MD; John Terrill Huggins, MD
Author and Funding Information

CORRESPONDENCE TO: John Terrill Huggins, MD, Division of Pulmonary, Critical Care, Allergy and Sleep Medicine, Medical University of South Carolina, 96 Jonathan Lucas St, Ste 812-CSB, MSC 630, Charleston, SC 29425-6300


Copyright 2016, American College of Chest Physicians. All Rights Reserved.


Chest. 2016;149(4):e111-e114. doi:10.1016/j.chest.2015.11.032
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Published online

An 83-year-old man with a history of chronic kidney disease (stage V) as a result of hypertensive nephrosclerosis and coronary artery disease was admitted to the hospital with dyspnea and bilateral lower extremity edema. Owing to oliguria and progressive renal dysfunction, hemodialysis was initiated the following day via a previously-placed left arm arteriovenous fistula. As a result of delirium and bradycardia, he required prolonged hospitalization. Three weeks into his course, he became hypothermic and obtunded.

Physical examination revealed a thin elderly man with the following vital signs: temperature, 33.8°C; pulse, 55 beats/min; respirations, 20 breaths/min; and blood pressure, 118/80 mm Hg. Cardiovascular examination was significant for bradycardia. Lung examination revealed decreased bibasilar air movement without adventitious sounds. His abdomen was scaphoid and not tender. Extremities showed bilateral 3+ edema to the level of the knees. Laboratory data showed a WBC count of 4.0 × 103/mm3 (previously 7.1), potassium of 2.9 mEq/L, and BUN/creatinine of 82/3.65 mg/dL. Owing to the leukopenia, hypothermia, and change in mental status, a sepsis work-up was initiated. A prior chest radiograph (not shown) revealed pleural effusions (right greater than left), bilateral lower lobe infiltrates, and mild pulmonary edema. Bedside abdominal ultrasound (AUS) was performed. The following ultrasound (US) videos were taken with a high-frequency probe over the anterior surface of the liver with the patient at 20° upright (Videos 1, 2).

Question: Based on the clinical information and US videos, what is the most likely diagnosis?

Answer: Pneumoperitoneum

Bedside US over the right lobe of the liver showed enhancement and thickening of the peritoneum with “comet tail” and “ring down” artifacts, consistent with pneumoperitoneum (Videos 1, 2). Surgery was consulted and confirmatory radiographs were obtained (Figs 1, 2). The patient’s age, declining status, multiple medical comorbidities, hypoalbuminemia, and evolving hemodynamic stability were reasons that exploratory laparoscopy was not pursued. CT imaging confirmed pneumoperitoneum with large air collection next to the second portion of the duodenum (not shown). The patient’s course improved with medical management, and surgery was not required. The cause of pneumoperitoneum was secondary to a perforated duodenal ulcer that spontaneously sealed.

Figure Jump LinkFigure 1 Upright portable chest radiograph shows the presence of free air under the diaphragm.Grahic Jump Location

Figure Jump LinkFigure 2 Left lateral decubitus abdominal radiograph shows the presence of a large pneumoperitoneum.Grahic Jump Location

Video 3 is a presentation of the Discussion topics. With the ability to image viscera, gallbladder, kidneys, and aorta, AUS as a bedside diagnostic modality for patients with acute abdominal pain, sepsis, and shock is growing. Pneumoperitoneum is often related to a perforated viscus and usually presents with peritonitis. Although this case was managed conservatively, pneumoperitoneum requires urgent surgical intervention in 90% of patients. With severe and acute abdominal pain, abdominal x-ray (AXR) or CT scans are often ordered reflexively. AUS should be considered in the critically ill and is likely underutilized by intensivists.

When gas is introduced into the peritoneum, bubbles form. Acoustic reflection develops when the US pulse reaches both the proximal and distal surface of the bubble. As a result, the transducer probe recognizes cyclic reverberating echoes (eg, A-lines and B-lines) caused by even a small volume of air.

Owing to air’s strong acoustic reflection and resultant sonographic artifacts, pneumoperitoneum produces several distinctive signs. The most well-recognized is the “enhanced peritoneal stripe sign” (EPSS), which was reported in 1999 (Videos 1, 2). The peritoneal stripe is normally thin and faint, located between the abdominal wall and the peritoneum. A single or double line may be seen. With the introduction of air (volumes as small as 1-2 mL), the peritoneal stripe becomes enhanced, thicker, and more echogenic. A large trial of 600 consecutive patients (21 with pneumoperitoneum) presenting with acute abdominal pain confirmed the utility of the EPSS, reporting no false-negative and 3 false-positive cases. Posterior ring down or comet tail artifacts (Video 2) may also be seen. Ring down artifact is distinguished by the echoes maintaining their width distally. Finally, patients with ascites may also show clear air bubbles, diagnostic of intraperitoneal air. Indirect findings consistent with pneumoperitoneum include intraabdominal fluid collections and local ileus.

In patients without pneumoperitoneum, “gut sliding” may be visualized. Analogous to lung sliding in the thorax, the presence of air between the mesothelial linings precludes visceral and parietal sliding. Thus, the presence of gut sliding excludes pneumoperitoneum. Similarly, “gut point” can be identified where gut sliding begins. In either the peritoneum or the pleura, if a single US image can visualize both serosal sliding and absence of sliding, air is present. Thus, gut point is diagnostic of pneumoperitoneum.

Although US may be performed anywhere on the abdomen, consistent yield has been reported in the right upper quadrant, overlying the right lobe of the liver. As free air moves to the least dependent area, the ideal position is supine with the head slightly elevated. Although any probe may be used, the linear array (higher resolution) probe is recommended because of better near-field resolution. Left lateral decubitus positioning can be performed to accentuate the air, allow for improved visualization, and ensure free air movement (sometimes referred to as the “shifting gas” sign or phenomenon). Practitioners should be aware that the lung may interpose the right upper quadrant during inspiration, but comparing inspiratory and expiratory variation should distinguish this appearance.

Reports as early as 1982 show that intraperitoneal volumes of air as small as 1 mL could be recognized by AXR and AUS. Subsequent canine studies have shown that intraperitoneal air volumes as low as 0.2 mL can be consistently identified by US. Also in canines, CT studies have been reported to consistently detect volumes as low at 0.5 mL. Although not directly compared in these studies, it appears that both US and CT are able to detect very small volumes of intraperitoneal air, and US may be able to detect even smaller volumes than CT.

Other studies have shown comparable or improved US testing characteristics compared with AXR. In 2002, Chen et al reported a higher US sensitivity (92%) compared with AXR (78%) for pneumoperitoneum. Using the EPSS, similarly high sensitivity and positive predictive value with higher specificity (99%) and negative predictive value (100%) were reported in a larger trial in 2007.

Compared with AXR or CT, AUS has intrinsic advantages owing to bedside availability and avoidance of transport, especially if repeat testing is needed. Avoiding iodinated contrast and radiation exposure are also appealing in children, pregnant women, and patients with chronic kidney disease. Furthermore, with skilled operators, AUS can potentially localize a site of perforation. US findings of local perforation include local visceral wall thickening. Sealed off peptic ulcers may have thickened walls and air in the ulcer. Lastly, AUS can provide diagnostic information not possible with AXRs (eg, disease of the gallbladder, kidneys, or aorta).

The limitations of AUS are related to operator-dependent image acquisition, nonpathologic air (ie, intraluminal air), and confounders such as obesity or subcutaneous emphysema. Also, perforation of retroperitoneal structures (eg, second or third parts of the duodenum or the ascending or descending colon) may result in abdominal catastrophe, producing retroperitoneal air. Finally, Chilaiditi syndrome is a rare condition in which a loop of colon interrupts the diaphragm and liver. The condition may cause abdominal pain or be asymptomatic, and AUS may look similar to free intraperitoneal air. The condition is often distinguished by using the left lateral decubitus view or respiratory variation.

AUS has the potential to diagnose and localize abdominal catastrophe at the bedside, has a higher sensitivity compared with AXR, and may potentially reduce the need for patient transport. Thus, intensivists should increasingly use AUS for bedside evaluation of the critically ill patient with undifferentiated sepsis, acute abdominal pain, and shock.

  • AUS is underutilized in the critical care setting.

  • AUS is able to recognize pneumoperitoneum in many cases at the bedside and is comparable to CT in the detection of free intraperitoneal air.

  • AUS findings of pneumoperitoneum include EPSS, posterior ring down, comet tail, and A-line artifacts.

  • Identification of gut sliding rules out pneumoperitoneum, and gut point rules in pneumoperitoneum.

  • Our imaging technique uses the linear probe over the right lobe of the liver in the supine or left lateral decubitus position.

  • AUS may provide bedside pneumoperitoneum diagnosis, reduce the need for critical care transportation, reduce exposure to radiation and nephrotoxic CT contrast, and allow a “trendable” examination for intensivists.

Financial/nonfinancial disclosures: None declared.

Other contributions:CHEST worked with the authors to ensure that the Journal policies on patient consent to report information were met.

Additional information: To analyze this case with the videos, see the online version of this article.

Muradali D. .Wilson S. .Burns P.N. .Shapiro H. .Hope-Simpson D. . A specific sign of pneumoperitoneum on sonography: enhancement of the peritoneal stripe. AJR Am J Roentgenol. 1999;173:1257-1262 [PubMed]journal. [CrossRef] [PubMed]
 
Ferrell E.A. .Graham J.P. . Ultrasound corner—diagnosis of pneumoperitoneum. Vet Radiol Ultrasound. 2003;44:307-308 [PubMed]journal. [CrossRef] [PubMed]
 
Asrani A. . Sonographic diagnosis of pneumoperitoneum using the ‘enhancement of the peritoneal stripe sign.’ A prospective study. Emerg Radiol. 2007;14:29-39 [PubMed]journal. [CrossRef] [PubMed]
 
Coppolino F. .Gatta G. .Di Grezia G. .et al Gastrointestinal perforation: ultrasonographic diagnosis. Crit Ultrasound J. 2013;5:S4- [PubMed]journal. [CrossRef] [PubMed]
 
Hefny A.F. .Abu-Zidan F.M. . Sonographic diagnosis of intraperitoneal free air. J Emerg Trauma Shock. 2011;4:511-513 [PubMed]journal. [PubMed]
 
Seitz K. .Reising K.D. . Ultrasound detection of free air in the abdominal cavity. Ultraschall Med. 1982;3:4-6 [PubMed]journal. [CrossRef]
 
Kim S.Y. .Park K.T. .Yeon S.C. .Lee H.C. . Accuracy of sonographic diagnosis of pneumoperitoneum using the enhanced peritoneal stripe sign in Beagle dogs. J Vet Sci. 2014;15:195-198 [PubMed]journal. [PubMed]
 
Marolf A. .Blaik M. .Ackerman N. .Watson E. .Gibson N. .Thompson M. . Comparison of computed radiography and conventional radiography in detection of small volume pneumoperitoneum. Vet Radiol Ultrasound. 2008;49:227-232 [PubMed]journal. [CrossRef] [PubMed]
 
Chen S.C. .Yen Z.S. .Wang H.P. .Lin F.Y. .Hsu C.Y. .Chen W.J. . Ultrasonography is superior to plain radiography in the diagnosis of pneumoperitoneum. Br J Surg. 2002;89:351-354 [PubMed]journal. [CrossRef] [PubMed]
 
Fujii Y. .Asato M. .Taniguchi N. .et al Sonographic diagnosis and successful nonoperative management of sealed perforated duodenal ulcer. J Clin Ultrasound. 2003;31:55-58 [PubMed]journal. [CrossRef] [PubMed]
 

Figures

Figure Jump LinkFigure 1 Upright portable chest radiograph shows the presence of free air under the diaphragm.Grahic Jump Location
Figure Jump LinkFigure 2 Left lateral decubitus abdominal radiograph shows the presence of a large pneumoperitoneum.Grahic Jump Location

Tables

References

Muradali D. .Wilson S. .Burns P.N. .Shapiro H. .Hope-Simpson D. . A specific sign of pneumoperitoneum on sonography: enhancement of the peritoneal stripe. AJR Am J Roentgenol. 1999;173:1257-1262 [PubMed]journal. [CrossRef] [PubMed]
 
Ferrell E.A. .Graham J.P. . Ultrasound corner—diagnosis of pneumoperitoneum. Vet Radiol Ultrasound. 2003;44:307-308 [PubMed]journal. [CrossRef] [PubMed]
 
Asrani A. . Sonographic diagnosis of pneumoperitoneum using the ‘enhancement of the peritoneal stripe sign.’ A prospective study. Emerg Radiol. 2007;14:29-39 [PubMed]journal. [CrossRef] [PubMed]
 
Coppolino F. .Gatta G. .Di Grezia G. .et al Gastrointestinal perforation: ultrasonographic diagnosis. Crit Ultrasound J. 2013;5:S4- [PubMed]journal. [CrossRef] [PubMed]
 
Hefny A.F. .Abu-Zidan F.M. . Sonographic diagnosis of intraperitoneal free air. J Emerg Trauma Shock. 2011;4:511-513 [PubMed]journal. [PubMed]
 
Seitz K. .Reising K.D. . Ultrasound detection of free air in the abdominal cavity. Ultraschall Med. 1982;3:4-6 [PubMed]journal. [CrossRef]
 
Kim S.Y. .Park K.T. .Yeon S.C. .Lee H.C. . Accuracy of sonographic diagnosis of pneumoperitoneum using the enhanced peritoneal stripe sign in Beagle dogs. J Vet Sci. 2014;15:195-198 [PubMed]journal. [PubMed]
 
Marolf A. .Blaik M. .Ackerman N. .Watson E. .Gibson N. .Thompson M. . Comparison of computed radiography and conventional radiography in detection of small volume pneumoperitoneum. Vet Radiol Ultrasound. 2008;49:227-232 [PubMed]journal. [CrossRef] [PubMed]
 
Chen S.C. .Yen Z.S. .Wang H.P. .Lin F.Y. .Hsu C.Y. .Chen W.J. . Ultrasonography is superior to plain radiography in the diagnosis of pneumoperitoneum. Br J Surg. 2002;89:351-354 [PubMed]journal. [CrossRef] [PubMed]
 
Fujii Y. .Asato M. .Taniguchi N. .et al Sonographic diagnosis and successful nonoperative management of sealed perforated duodenal ulcer. J Clin Ultrasound. 2003;31:55-58 [PubMed]journal. [CrossRef] [PubMed]
 
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