The First Smartphone Application for Microsurgery Monitoring

BACKGROUND: Postoperative monitoring of free flap tissue perfusion is vital. Devices available are expensive and complex to operate. Most surgeons rely on direct clinical observation. A monitoring system that is reliable, inexpensive, and easy to operate is needed. Using mobile phone technology, the authors developed and evaluated a new free flap monitoring system: SilpaRamanitor. METHODS: Software was developed for Android-operated mobile phones. Forty-two normal subjects were recruited to assess its effectiveness. Varying degrees of pressure were applied around the index finger to produce partial venous occlusion, partial arterial occlusion, complete venous occlusion, and complete arterial occlusion sequentially. Photographs of each subject's index and middle fingers were taken using the smartphone camera. To detect the abnormal perfusion presented on the index finger, the application was instructed to analyze photographs for color difference, with the unoccluded middle finger serving as the control. RESULTS: The sensitivity, specificity, accuracy, false-negative results, and false-positive results were 94, 98, 95, 6, and 1 percent, respectively. The accuracy of the application in grading occlusion severity was also evaluated. Thirty-nine cases (93 percent) were correctly identified as venous occlusion. The occlusion severity was correctly identified in 33 cases (85 percent). Likewise, for the 40 cases (95 percent) correctly identified as arterial occlusion, the method correctly categorized its severity in 33 cases (83 percent). CONCLUSIONS: The authors developed a new, accurate, and reliable diagnostic system for postoperative microsurgery monitoring using a smartphone application. SilpaRamanitor is inexpensive and easy to use, making it applicable in many microsurgical settings. CLINICAL QUESTION/LEVEL OF EVIDENCE: Diagnostic, IV.