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Introduction: Percutaneous renal biopsy technique was introduced into clinical practice in the early 1950s and has since represented an irreplaceable method for studying renal diseases. It has contributed to their anatomoclinical classification and deepened our understanding of etiopathogenic mechanisms. This invasive exploration should be individually indicated, depending on the clinical picture and a careful balance between risks and benefits for each patient. There are situations where the biopsy provides significant information, justifying its performance, while in other circumstances, the risk outweighs the potential benefits, making the indication for the technique doubtful or even dangerous.
In patients requiring mechanical ventilation, the use of percutaneous renal biopsy may exacerbate organ dysfunction, affecting the renal and cardiovascular systems. This can be attributed to the activation of neuroendocrine pathways, hemodynamic disturbances, and the release of proinflammatory mediators.
Due to the limited use of renal biopsies, the histopathological spectrum of acute kidney injury (AKI) and ventilation remains less defined. This may be due to a lack of biopsy reports in ventilated patients or the establishment of a biopsy technique for such cases. Only one study has specifically addressed biopsy results for AKI in intubated patients, reporting differences in biopsy approaches without establishing post-biopsy evolution and measures taken during the procedure.
Objective: To present a report on three biopsies in ventilated patients, establishing conditions for intubated patients and post-biopsy complications to develop a protocol for biopsy procedures in patients with advanced airway management and the associated risks.
Three biopsies were performed on patients under mechanical ventilation and deep sedation, with vasopressor use and biochemical abnormalities such as anemia, thrombocytopenia, and elevated azotemia. Among the three patients (2 females, including one pregnant, and 1 male) with an average age of 26 years, all experienced acute deterioration of renal function. Ultrasound-guided biopsy was performed without a breath-holding maneuver, and two patients received unfractionated heparin, which was discontinued 12 hours before the procedure. Two patients underwent plasma exchange, and two required renal replacement therapy. The patient biopsied in the prone position developed a self-limiting hematoma without further complications. Follow-up with ultrasound showed no hemodynamic instability or need for additional procedures.
Of the three related biopsies, one revealed membranous glomerulopathy, another showed active fibrous proliferative extracapillary glomerulonephritis with pauciimmune sclerotic class ANCA PR3-associated sclerosis, and the third reported active tubulointerstitial nephritis with multifocal acute tubular injury and moderate regenerative changes in the epithelium, along with pigment tubulopathy. The histopathological diagnosis had immediate consequences for clinical management, including the use of corticosteroids, plasma exchange, and rituximab.
The lateral position for biopsy in ventilated patients demonstrated a surprisingly high diagnostic yield and no complications in critical patients compared to Conlon et al.'s 1995 study, which found no advantage of surgical over percutaneous renal biopsies in these patients. None of our patients suffered procedure-related consequences, and the high 30-day mortality reflects the underlying severity of critical illness in our study population. Our data may encourage other providers not to shy away from indicated renal biopsies, even in intubated patients.
This case review was conducted to demonstrate the feasibility of a reproducible biopsy protocol in any ICU setting and to study the diagnostic performance and complication rate in these circumstances. Although the number of cases in our center is limited, the technique will continue to be implemented due to its high diagnostic yield and impact on patient prognosis based on renal biopsy information.