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Transient apnoea for motion control during flexible ureteroscopic lithotripsy: a randomised trial
Jiahuan Yu1, Yi Zhou2, Xiaolei Shi3
1Department of Health Management Centre, The First Affiliated Hospital of Naval Medical University, Shanghai, China.
Objectives:
To determine whether transient apnoea (TA) during flexible ureteroscopic laser lithotripsy improves active lithotripsy efficiency compared with regular mechanical ventilation (RMV) and small tidal-volume ventilation (STVV).
Patients And Methods:
In this single-centre, three-arm randomised trial, 150 adults with a single computed tomography (CT)-confirmed renal, ureteropelvic, or proximal ureteric stone measuring 10-<20 mm were assigned one-to-one-to-one to RMV, STVV, or TA. TA followed 5-min 100% oxygen pre-oxygenation, with 9-min maximum and pre-specified stopping criteria under continuous anaesthetic monitoring. The primary endpoint was active lithotripsy efficiency, defined as CT-estimated stone volume divided by elapsed active lithotripsy time. Analyses followed the intention-to-treat principle.
Results:
The mean (standard deviation) active lithotripsy efficiency was 27.8 (8.9), 26.6 (8.0), and 34.3 (10.0) mm3/min with RMV, STVV, and TA, respectively (P < 0.001). TA increased adjusted efficiency by 5.9 mm3/min vs RMV (95% confidence interval [CI] 2.2-9.6 mm3/min) and 6.8 mm3/min vs STVV (95% CI 3.3-10.2 mm3/min). The median active lithotripsy time was 27.5, 26.5, and 22.0 min (P = 0.001); total operative time was 50.0, 50.0, and 43.0 min (P = 0.002); and surgeon-rated targeting stability scores were 7.0, 7.0, and 9.0 (P < 0.001), respectively. Postoperative Day 1/1-month stone-free rates were 88%/92%, 80%/96%, and 88%/90%, respectively, with no significant between-group differences. The median (interquartile range) achieved apnoea duration was 5.0 (4.5-6.8) min; 46/50 resumed ventilation before the 9-min maximum, most commonly for heart-rate decline/bradycardia (n = 27) or blood-pressure decline/hypotension (n = 20). No patient had a peripheral oxygen saturation <90% or a Clavien-Dindo Grade ≥III complication; transient hypercapnia and respiratory acidosis improved after ventilation resumed.
Conclusion:
Transient apnoea improved lithotripsy efficiency and shortened operative time compared with RMV and STVV, with higher surgeon-rated targeting stability. The benefit was primarily intraoperative, without evidence of greater postoperative stone clearance. Protocolised TA may provide a brief intraoperative motion-control option with pre-oxygenation, continuous anaesthetic monitoring, and individualised termination.
