In this paper, we propose a novel data augmentation technique employing multivariate Gaussian distribution (DA-MGD) for neural network (NN)-based blood pressure (BP) estimation, which incorporates the relationship between the features in a multi-dimensional feature vector to describe the correlated real-valued random variables successfully. To verify the proposed algorithm against the conventional algorithm, we compare the results in terms of mean error (ME) with standard deviation and Pearson correlation using 110 subjects contributed to the database (DB) which includes the systolic BP (SBP), diastolic BP (DBP), photoplethysmography (PPG) signal, and electrocardiography (ECG) signal. For each subject, 3 times (or 6 times) measurements are accomplished in which the PPG and ECG signals are recorded for 20 s. And, to compare with the performance of the BP estimation (BPE) using the data augmentation algorithms, we train the BPE model using the two-stage system, called the stacked NN. Since the proposed algorithm can express properly the correlation between the features than the conventional algorithm, the errors turn out lower compared to the conventional algorithm, which shows the superiority of our approach.

Background: Conventional radial forearm free flaps (RFFFs) are known to be safe, but can result in donor site complications. Based on our experiences with suprafascial and subfascial RFFFs, we evaluated the safety of flap survival and surgical outcomes.Methods: This was a retrospective study of head and neck reconstructions using RFFFs from 2006 to 2021. Thirty-two patients underwent procedures using either subfascial (group A) or suprafascial (group B) dissection for flap elevation. Data were collected on patient characteristics, flap size, and donor and recipient complications, and the two groups were compared.Results: Thirteen of the 32 patients were in group A and 19 were in group B. Group A included 10 men and three women, with a mean age of 56.15 years, and group B included 16 men and three women, with a mean age of 59.11 years. The mean defect areas were 42.83 cm² and 33.32 cm², and the mean flap sizes were 50.96 cm² and 44.54 cm² in groups A and B, respectively. There were 13 donor site complications: eight (61.5%) in group A and five (26.3%) in group B. Flexor tendon exposure occurred in three patients in group A and in none in group B. All flaps survived completely. A recipient site complication occurred in two patients (15.4%) in group A and three patients (15.8%) in group B.Conclusions: Complications and flap survival were similar between the two groups. However, tendon exposure at the donor site was less prevalent in the suprafascial group, and the treatment period was shorter. Based on our data, suprafascial RFFF is a reliable and safe procedure for reconstruction of the head and neck.

The coverage of extensive soft tissue defects requires several considerations, such as limited donor sites, reconstruction methods, and the outcome of functional recovery. In the cases described herein, when a significant soft tissue defect was present on an extremity, we opted for staged reconstruction. We first performed a split-thickness skin graft (STSG) to reduce the soft tissue defect, using the anterolateral thigh (ALT) as the donor site. In the second stage, the remaining soft tissue defect was reconstructed with an ALT free flap, utilizing the same lateral thigh area that had previously served as the STSG donor site. After the free flap procedure, we encountered several challenges in monitoring the ALT flap; however, all flaps ultimately survived. To the best of our knowledge, this is the first report of using an ALT free flap following STSG from the same donor site, demonstrating efficient tissue utilization. We believe this approach is beneficial for reconstructing extensive soft tissue defects, as it maximizes tissue use efficiency and reduces donor site morbidity when donor options are limited.