1 Background

Emphysematous pyelonephritis (EPN) is a rare but severe, fulminant infection of the renal parenchyma and the surrounding tissues that most often occurs in patients with uncontrolled diabetes mellitus and/or debilitated state. The infection usually caused by gas forming organisms (Escherichia coli and K. pneumoniae) with air in the collecting system, renal parenchyma, and/or perirenal structures [1]. The disease process can be lethal if not diagnosed and managed promptly as mortality rates up to 40% have been reported [2]. Initial management includes fluid resuscitation of the patient, broad spectrum antibiotics. Multiple percutaneous nephrostomies or urgent nephrectomy may be needed for successful management of severe EPN [3,4,5]. We describe a case of severe EPN with air bubble in the IVC where emergent nephrectomy was planned.

2 Case presentation

A 35-year-old obese Hispanic female with past medical history of poorly controlled insulin-dependent diabetes mellitus (Hb A1c: 11.3%) presented to emergency room with change in mental status and frequent vomiting. She was febrile and hemodynamically unstable with clinical picture of septic shock. She coded in the emergency room requiring five minutes of cardiopulmonary resuscitation and endotracheal intubation. Prompt CT scan revealed EPN with air bubbles extending to the renal vein, inferior vena cava (IVC), and pulmonary artery (Figs. 1, 2). The patient was subsequently admitted to the intensive care unit, and a urology consultation was sought for further evaluation and management. Subsequently, she was transported to operating for an emergent nephrectomy. On the operating table, she went into cardiac arrest and cardiopulmonary resuscitation was administered according to American Heart Association guidelines. Despite sustained efforts, the patient died after 40 min of commencement of CPR.

Fig. 1
figure 1

Arrow demonstrates air in the inferior vena cava in coronal (a) and axial (b) views

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Fig. 2
figure 2

Arrow demonstrates air in the pulmonary artery in sagittal (a) and axial (b) views

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3 Discussion

The presented case report describes the unfortunate lethal complication of a patient suffering from an E. coli-induced grade 3 EPN [1, 5] scheduled for an emergency nephrectomy. EPN is a rare but potentially fatal renal infection most prevalent in diabetic, alcoholic, and immuno-compromised patients [1,2,3,4,5,6]. CT scan is the gold standard for diagnosis of EPN and provides valuable information for planning further treatment [1,2,3,4,5,6]. Although controversial, conservative management and renal preservation using percutaneous drainage and high dose antibiotics are considered in mild cases (classification class I–II) [1, 3, 5], nephrectomy is the treatment of choice in severe cases (class III–IV) with a mortality rate of 20% compared to 80% in medically managed patients [5]. Two clinical scenarios may explain the quick hemodynamic deterioration and fatal outcome despite all efforts. A more likely cause of the patient’s demise was hemodynamic collapse secondary to septic shock. Another contributor may have been air emboli originating from gas in the renal vein and inferior vena cava (IVC), which may have mobilized during transport causing acute right heart failure. Preclinical studies suggest that large quantities of gas (over 50 ml) are required to cause abrupt acute cor pulmonale, asystole, or both [7, 8]. The results of the CT scan reveal air in the vascular system and large quantities of air within the kidney. An estimation by planimetry of the CT scan acquired hours before the transport suggests an air volume of approximately 177 ml in the kidney and renal collecting ducts and approximately 4 ml in the IVC. Air emboli may occur during orthopedic procedures [9] vascular procedures, neurosurgical interventions [10], or laparoscopic surgeries [11, 12]. In contrast, our case of EPN might present an unreported incident of an endogenously developed air embolus from the kidney. Lastly, a combination of severe septic shock and multiple air emboli may have caused the hemodynamic collapse. However, only an autopsy would bring light to the actual reason of death. Unfortunately, autopsy was declined by the family. Therefore, the cause of death remains speculative.

4 Conclusion

This case demonstrates that patients presenting with severe EPN have a high mortality risk and providers should acknowledge that septic shock, endogenous air emboli mobilized from the kidney, or a combination of both can result in cardiovascular collapse. Hemodynamic optimization and concise cardiac monitoring is of utmost importance to increase the chance of survival during the perioperative period.