Introduction: Urinary obstruction (UO) or failure to void has been observed during several episodes of short-duration spaceflight, necessitating bladder catheterization. It should be considered a possible medical condition in long-duration space missions as well. Antiemetics used early in space flight add to the risk and severity of voiding problems, along with the sensory and psychological peculiarities of voiding without gravity and in the unusual setting of a spacecraft. Urolithiasis due to the above-normal calcium excretion increases the risk of UO in long duration space missions. Finally, the individual risk of UO is higher against the background of preexisting conditions such as benign prostatic hyperplasia (BPH) or urethral stricture. Both acute retention and ureteral obstruction are associated with substantial patient distress, and carry a risk of urosepsis and/or acute renal failure. If UO in orbital flight is unresolved or complicated, it would likely result in crew emergency return from orbit. Exploration missions, however, may require means for definitive treatment of urinary tract obstruction. This study documents successful ultrasound-guided percutaneous catheterization of the urinary bladder in microgravity. A porcine model of urethral occlusion was used. The results demonstrate an additional capability from our previous investigations describing endoscopic catheterization and stenting of the ureters in microgravity conditions.
Methods: In an anesthetized porcine model, a Foley catheter was placed in the bladder and clamped after instillation of 200 ml of colored liquid. The bladder was visualized and then drained under ultrasound guidance through suprapubic puncture, employing a 10.3 F pigtail catheter with introducer. The procedural elements were conducted only during microgravity portions of the parabolic flight.
Results: Ultrasound imaging was used to successfully perform image-guided percutaneous puncture through the anterior bladder wall with the catheter, without injury to adjacent organs. The percutaneous catheter was able to successfully drain the bladder in microgravity conditions.
Conclusions: Percutaneous bladder catheterization and drainage can be successfully performed in weightless conditions under ultrasound guidance. Ultrasound provides a low-power, portable means to safely conduct minimally invasive procedures in pertinent organs and tissues. Percutaneous bladder catheterization is a standard procedure when luminal bladder catheterization is not possible; this technique can be successfully modified for use in space medicine applications.