Point-of-care ultrasound for emergency pericardiocentesis: a multidimensional CUSUM analysis of the learning curve

Emergency point-of-care ultrasound-guided percutaneous pericardial catheter drainage (US-GPPCD) is a life-saving intervention for cardiac tamponade, yet the learning curve among novice operators in emergency settings remains poorly characterized, especially for multidimensional metrics and operator positioning. This study aimed to evaluate the learning curve, procedural efficiency, operator confidence, complications, and the influence of operator positioning for US-GPPCD performed by a single novice operator under direct supervision. A total of 33 consecutive patients undergoing US-GPPCD between October 2024 and December 2025 by a single novice operator without prior independent experience were enrolled. Procedural metrics were prospectively recorded immediately post-procedure, while clinical data were retrospectively collected. Demographic and clinical characteristics, procedure time, needle insertion site localization time, operator confidence score, operator position, and complications were analyzed. Three separate cumulative sum (CUSUM) learning curves were constructed for multidimensional learning curve analysis. CUSUM analysis divided the learning curve into two phases: phase 1 (cases 1–14, skill-acquisition) and phase 2 (cases 15–33, skill-proficiency). Procedure time and localization time were significantly longer, and operator confidence score was significantly lower, in phase 1 than in phase 2 (all P < 0.01). The complication rate was higher in phase 1 (28.6%) than in phase 2 (5.3%), with no statistically significant difference (P = 0.14). While left-side positioning was associated with shorter procedure time in unadjusted analysis, this effect was confounded by operator experience and not significant after adjustment. In this exploratory analysis, US-GPPCD showed acceptable short-term safety under direct supervision. A significant inflection point in procedural efficiency was observed at approximately 14 cases, while operator confidence consolidated shortly thereafter. These findings provide preliminary, hypothesis-generating evidence that may inform future training protocols, but require validation across multiple operators and centers.