Risk factors for pedicled flap necrosis in hand soft tissue reconstruction: a multivariate logistic regression analysis

Vasopressor use in partial flap necrosis in free flap transplant patients with vascular comorbidities: A retrospective study

Intraoperative use of vasopressors in free flap surgeries is controversially debated. The predominant concern is that pedicle blood supply will decrease leading to post-operative complications. This study examined the role of intraoperative vasopressors, specifically norepinephrine, in free flap partial necrosis based on the patients' comorbidities. We retrospectively analyzed 192 patients who received free flap treatment between 2006 and 2021 and were stratified based on vascular comorbidities. We assessed the role of intraoperative vasopressors using multivariate analysis. Patients who were administered vasopressors did not have a significantly higher risk of partial flap necrosis compared to patients who were not administered vasopressors (OR: 1.439, 95% CI: 0.618-3.348, p=0.399). Upon stratifying by vascular comorbidities, we found that patients with two or more vascular comorbidities who were administered vasopressors had a significantly higher risk of developing flap necrosis (OR: 3.882, 95% CI: 1.266-14.752, p=0.046), indicating that vasopressor use in patients with multiple vascular comorbidities is a risk factor for partial flap necrosis. To minimize the risk of flap marginal necrosis in patients with vascular comorbidities, we recommend limited use of vasopressors or minimizing the flap area to preserve vascularization.

A strong reconstruction option for tissue loss on hand and wrist due to firearm injury in the Syrian war: Reverse posterior interosseous flap

All of the injuries were the open injuries with bone or tendon structures in the hand and wrist region as a result of the firearm injury (FI) in the Syria. In the study, we assessed the outcomes of the posterior interosseous flap (PIF) on hand and wrist that we used for the Syrian injured people including civilians and soldiers in this War. PIF was applied to 77 patients who composed of 43 female and 34 male that all patients were evaluated for tissue loss resulting from gunshot wounds and injured in the War between 2014 and 2020 years with tissue loss in hand and wrist as a result of FI. The flap survival rate was 100% for all the patients. The dimensions of flaps ranged from 4.1 cm × 2.2 cm to 9cm × 5.4 cm with 0.51 ± 0.12 cm thickness. The mean pedicle length was 6.33 ± 1.08 cm. The surgery for PIF took 68.8 ± 22.1 minutes, while blood loss was 60 ± 24 mL. We observed no palsy conditions including the posterior interosseous nerve. The donor sites were treated by primary intention in the patients. We found the superiority of PIF with the postoperative follow-up comfort, ease of fracture healing, easy and fast, easy-to-apply method and no second additional session requirement in FI patients. We did not detect flap necrosis in any patient or observe a flap-related complication. As a result of the present study, it strongly supports the thesis that PIF is the best option in these cases.

Viability of transverse rectus abdominis musculocutaneous flap treated with photobiomodulation and therapeutic ultrasound: an experimental model

Report the effects of photobiomodulation (PBM) and therapeutic ultrasound (TUS) on the viability of TRAM in mice.

MATERIALS AND METHODS

Fifty-five mice Swiss were subjected to treatment for 5 days. Group 1, treatment was performed with the agents switched off. Groups 2 to 5 were treated with different wavelengths 660 and 830 nanometers (nm) and groups 6 to 11 with TUS of 1 and 3 MHz frequency. Macrometric analyses were performed using a specific camera and analyzed by the ImageJ® software. Thermographic analyses were performed with the Flir C2 and analyzed using the FLIR Tools software.

RESULTS

Group 9 obtained 95% of viable area on the 3rd day and 85% on the 5th day, showing the effectiveness of the TUS in the flap viability. Regarding skin temperature, there was a difference only in the immediate postoperative period in group 1, which had a lower temperature than the other groups.

CONCLUSIONS

TUS demonstrated greater efficiency in maintaining the viability of TRAM. PBM 830 nm also demonstrated good results in the viability of TRAM.

The alarming problems of confounding equivalence using logistic regression models in the perspective of causal diagrams

Background

Confounders can produce spurious associations between exposure and outcome in observational studies. For majority of epidemiologists, adjusting for confounders using logistic regression model is their habitual method, though it has some problems in accuracy and precision. It is, therefore, important to highlight the problems of logistic regression and search the alternative method.

Methods

Four causal diagram models were defined to summarize confounding equivalence. Both theoretical proofs and simulation studies were performed to verify whether conditioning on different confounding equivalence sets had the same bias-reducing potential and then to select the optimum adjusting strategy, in which logistic regression model and inverse probability weighting based marginal structural model (IPW-based-MSM) were compared. The “do-calculus” was used to calculate the true causal effect of exposure on outcome, then the bias and standard error were used to evaluate the performances of different strategies.

Results

Adjusting for different sets of confounding equivalence, as judged by identical Markov boundaries, produced different bias-reducing potential in the logistic regression model. For the sets satisfied G-admissibility, adjusting for the set including all the confounders reduced the equivalent bias to the one containing the parent nodes of the outcome, while the bias after adjusting for the parent nodes of exposure was not equivalent to them. In addition, all causal effect estimations through logistic regression were biased, although the estimation after adjusting for the parent nodes of exposure was nearest to the true causal effect. However, conditioning on different confounding equivalence sets had the same bias-reducing potential under IPW-based-MSM. Compared with logistic regression, the IPW-based-MSM could obtain unbiased causal effect estimation when the adjusted confounders satisfied G-admissibility and the optimal strategy was to adjust for the parent nodes of outcome, which obtained the highest precision.

Conclusions

All adjustment strategies through logistic regression were biased for causal effect estimation, while IPW-based-MSM could always obtain unbiased estimation when the adjusted set satisfied G-admissibility. Thus, IPW-based-MSM was recommended to adjust for confounders set.

Electronic supplementary material

The online version of this article (10.1186/s12874-017-0449-7) contains supplementary material, which is available to authorized users.