Cautionary Tales

Editor's Note: Our president-elect, Sue Kost, suggested “Cautionary Tales” as an idea for an ongoing newsletter column and has contributed the first submission. The goal of the column is to provide a forum for sharing sedation-related mishaps in hopes that others can avoid the same mistakes. The format is intended to be casual; references are welcomed but not required. Of course, names, ages and other exact details may be altered in order to maintain HIPAA compliance.

Two Renal Biopsies

By Susanne Kost, MD, FAAP, FACEP

I’d like to share the tale of two renal biopsies at our institution, both involving airway-related sedation complications from the same purported mechanism. Both patients underwent the procedures with deep sedation in the prone position with a natural airway.

The first event involved a 5-yo 19-kg patient with steroid-resistant nephrotic syndrome. Other than her renal disease, she was healthy, with no underlying airway pathology, history of recent URI or gastroesophageal reflux.

She underwent ultrasound-guided needle biopsy of a native left kidney under deep sedation with propofol and ketamine. She was positioned prone, with a folded sheet under her abdomen to stabilize the kidney, per the preference of the nephrologist. The induction was uneventful, and the nephrologist was successful in obtaining the first biopsy sample. He then applied (vigorous) pressure to the biopsy site.

Almost immediately, ETCO2 tracing was lost and oxygen saturations dropped. The patient was rapidly turned to a supine position and suctioned, and her airway was repositioned. Laryngospasm was suspected, and positive pressure was applied along with the laryngospasm maneuver. An additional dose of propofol 1 mg/kg was administered. Lowest pulse oximetry reading was 80% for one minute. A subsequent attempt to turn her prone was not tolerated due to recurrence of airway obstruction despite an oral airway, and the decision was made to stop the procedure without a desired second sample, rather than escalate to anesthesia with an artificial airway. She recovered uneventfully without additional intervention.

The second case, performed by the same nephrologist a few months later, involved an 11-yo 49-kg boy with HSP. He was otherwise healthy, status post-remote adenoidectomy but no recent URI, snoring history, or reflux. He too underwent US-guided biopsy of a native left kidney in the prone position with an abdominal roll underneath.

Propofol induction was uneventful, supplemented with 0.5 mg/kg ketamine.  The nephrologist was successful in obtaining two biopsy samples, deemed adequate, and once again, pressure was applied to the biopsy site. The patient immediately developed coughing with copious oral secretions and oxygen desaturation to the low 70s for about a minute. He was turned supine and suctioned, and CPAP was applied. Breath sounds were notable for bilateral rhonchi.

He recovered uneventfully in the immediate post-procedure period; however, a chest x-ray was ordered six hours later by the inpatient team when he spiked a fever to 38.5 (all of our renal biopsy patients are routinely admitted overnight). Oxygen saturations remained normal in room air. CXR was read as “Bilateral perihilar streaky opacities; may represent atelectasis, although early aspiration pneumonitis is not entirely excluded.” Rhonchi and fever resolved by the next day, and he was discharged without further sequelae.

We postulate that direct pressure over the kidney of a prone patient was translated to the stomach, aggravated by the presence of the abdominal roll, likely forcing stomach contents up the esophagus and causing airway irritation. Both patients met standard NPO criteria, and neither had additional risk factors for laryngospasm.

One could argue that the use of ketamine may have contributed; however, we have not experienced similar complications with the same sedative regimen with renal biopsies by a different nephrologist who does not apply (as much) direct pressure to the kidney post-biopsy. We have since strongly cautioned against over-zealous post-procedure pressure while the patient is still prone, opting instead for a sandbag under the kidney once the patient is turned supine with the head slightly elevated.

I was unable to find evidence in the literature that direct pressure over the kidney immediately post-biopsy lessens the likelihood of perinephric hematoma or other bleeding complications. Significant post-biopsy bleeding is associated with significant hypertension or underlying coagulopathies,1 and post-biopsy bleeding is relatively uncommon in children.

A recent retrospective review of complications showed 11 significant bleeds (defined as more than a 2.5 cm perirenal hematoma, drop in hemoglobin by >10%, or bleeding into the collecting system) in 438 biopsies in 295 patients in one center. Of those 11 bleeds, eight were in native kidneys and three required transfusion2. The timing and degree of post-biopsy pressure application was not mentioned. Sedation-related complications during renal biopsies have also been reviewed, with no serious outcomes in one series, although competent airway management skills are warranted, as 12% of the 174 sedated patients in this series required CPAP at some point. Overall procedural success was 94%3.

Moral of the story: Pressure on the back of a prone patient, especially with a roll under the abdomen, may cause reflux and subsequent airway compromise. Be prepared.


  1. Li, CH, Traube LE, et al. Implementation and results of a percutaneous renal allograft biopsy protocol to reduce complication rate. J Am Coll Radiol 2016;13:549-53.
  2. Franke, M. Ultrasound-guided percutaneous renal biopsy in 295 children and adolescents: Role of ultrasound and analysis of complications. PLoS One. 2014; 9(12): e114737. Published online 2014 Dec 9. doi: 10.1371/journal.pone.0114737.
  3. Kamat PP, Ayestaran FW, et al. Deep procedural sedation by a sedationist team for outpatient pediatric renal biopsies. Pediatr Transplantation 2016; 20:372-7.

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