Extended arc of rotation of Latissimus Dorsi Musculocutaneous Flap providing well-vascularized tissue for reconstruction of complete defects of the sternum: An anatomical study of flap pedicle modification.

BACKGROUND: Deep sternal wound infections (DSWI) following cardiothoracic surgery represent a life quality endangering sequelae and may lead to sternal osteomyelitis. Radical debridement followed by Negative Pressure Wound Therapy (NPWT) may achieve infection control, provide angiogenesis, and improve respiratory function. When stable wound conditions have been established a sustainable plastic surgical flap reconstruction should be undertaken. OBJECTIVE: This study analyses a method to simplify defect coverage with a single Latissimus Dorsi Myocutaneous Flap (LDMF). METHODS: Preparation of 20 LDMF in ten fresh frozen cadavers was conducted. Surgical steps to increase pedicle length were evaluated. The common surgical preparation of LDMF was compared with additional transection of the Circumflex Scapular Artery (CSA). RESULTS: Alteration of the surgical preparation of LDMF by sacrificing the CSA may provide highly valuable well-vascularized muscle tissue above the sensitive area of the Xiphisternum. All defects could be completely reconstructed with a single LDMF. The gain in length of flap tissue in the inferior third of the sternum was 3.86±0.9 cm (range 2.2 to 8 cm). CONCLUSIONS: By sacrificing the CSA in harvesting the LDMF a promising gain in length, perfusion and volume may be achieved to cover big sternal defects with a single flap.

An ACS-NSQIP Data Analysis of 30-Day Outcomes Following Surgery for Bell's Palsy.

BACKGROUND: There exists a paucity of large-scale, multi-institutional studies that investigate the outcomes of surgery for Bell's palsy (BP). Here, we utilize a large, multi-institutional database to study the risk factors and early-stage outcomes following surgical procedures in BP. METHODS: We reviewed the American College of Surgeons National Surgical Quality Improvement Program database (2008-2019) to identify patients who underwent surgery for the diagnosis of BP. We extracted data on comorbidities and preoperative blood values, and 30-day postoperative outcomes. RESULTS: Two hundred fifty-seven patients who underwent surgery for BP symptoms over the 12-year review period were identified. Muscle grafts (n=50; 19%) and fascial grafts (n=48; 19%) accounted for the majority of procedures. The most common comorbidities were hypertension (n=89; 35%) and obesity (n=79; 31%). Complications occurred in 26 (10.1%) cases. Additionally, length of hospital stay was significantly associated with both surgical and medical complications (3.9±4.7 versus 1.5±2.0; P <0.01) and (3.2±3.8 versus 1.4±2.0; P <0.01), respectively. Preoperative creatinine, blood urea nitrogen, and alkaline phosphatase were identified as potential predictors of poor postoperative outcomes. CONCLUSION: Based on multi-institutional analysis, complication rates following surgery for BP were found to be overall low and seen to correlate with length of hospital stay. Reoperations and readmissions were the most frequent complications after surgery for BP. The preoperative evaluation of routine laboratory values may help refine patient eligibility and risk stratification. In addition, our findings call for future large-scale prospective studies in the field of facial palsy surgery to further improve the quality of care and optimize perioperative protocols.

The masseteric nerve for facial reanimation: Macroscopic and histomorphometric characteristics in 106 human cadavers and comparison of axonal ratio with recipient nerves.

Peripheral facial palsy causes severe impairments. Sufficient axonal load is critical for adequate functional outcomes in reanimation procedures. The aim of our study was to attain a better understanding of the anatomy of the masseteric nerve as a donor, in order to optimize neurotization procedures. Biopsies were obtained from 106 hemifaces of fresh frozen human cadavers. Histological cross-sections were fixed, stained with PPD, and digitized. Histomorphometry and a validated software-based axon quantification were conducted. Of the 154 evaluated branches, 74 specimens were of the main trunk (MT), 40 of the anterior branch (AB), and 38 of the descending branch (DB), while two halves of one cadaver featured an additional branch. The MT showed a diameter of 1.4 ± 0.41 mm (n = 74) with 2213 ± 957 axons (n = 55). The AB diameter was 0.9 ± 0.33 mm (n = 40) with 725 ± 714 axons (n = 30). The DB diameter was 1.15 ± 0.34 mm (n = 380) with 1562 ± 926 axons (n = 30). The DB demonstrated a high axonal capacity - valuable for nerve transfers or muscle transplants. Our findings should facilitate a balanced selection of axonal load, and are potentially helpful in achieving more predictable results while preserving masseter muscle function.

Diagnosing lagophthalmos using artificial intelligence.

Lagophthalmos is the incomplete closure of the eyelids posing the risk of corneal ulceration and blindness. Lagophthalmos is a common symptom of various pathologies. We aimed to program a convolutional neural network to automatize lagophthalmos diagnosis. From June 2019 to May 2021, prospective data acquisition was performed on 30 patients seen at the Department of Plastic, Hand, and Reconstructive Surgery at the University Hospital Regensburg, Germany (IRB reference number: 20-2081-101). In addition, comparative data were gathered from 10 healthy patients as the control group. The training set comprised 826 images, while the validation and testing sets consisted of 91 patient images each. Validation accuracy was 97.8% over the span of 64 epochs. The model was trained for 17.3 min. For training and validation, an average loss of 0.304 and 0.358 and a final loss of 0.276 and 0.157 were noted. The testing accuracy was observed to be 93.41% with a loss of 0.221. This study proposes a novel application for rapid and reliable lagophthalmos diagnosis. Our CNN-based approach combines effective anti-overfitting strategies, short training times, and high accuracy levels. Ultimately, this tool carries high translational potential to facilitate the physician's workflow and improve overall lagophthalmos patient care.

Histomorphometry of the Sural Nerve for Use as a CFNG in Facial Reanimation Procedures.

Facial palsy (FP) is a debilitating nerve pathology. Cross Face Nerve Grafting (CFNG) describes a surgical technique that uses nerve grafts to reanimate the paralyzed face. The sural nerve has been shown to be a reliable nerve graft with little donor side morbidity. Therefore, we aimed to investigate the microanatomy of the sural nerve. Biopsies were obtained from 15 FP patients who underwent CFNG using sural nerve grafts. Histological cross-sections were fixated, stained with PPD, and digitized. Histomorphometry and a validated software-based axon quantification were conducted. The median age of the operated patients was 37 years (5-62 years). There was a significant difference in axonal capacity decrease towards the periphery when comparing proximal vs. distal biopsies (p = 0.047), while the side of nerve harvest showed no significant differences in nerve caliber (proximal p = 0.253, distal p = 0.506) and axonal capacity for proximal and distal biopsies (proximal p = 0.414, distal p = 0.922). Age did not correlate with axonal capacity (proximal: R = -0.201, p = 0.603; distal: R = 0.317, p = 0.292). These novel insights into the microanatomy of the sural nerve may help refine CFNG techniques and individualize FP patient treatment plans, ultimately improving overall patient outcomes.

Artificial intelligence-enabled simulation of gluteal augmentation: A helpful tool in preoperative outcome simulation?

BACKGROUND: While the buttock region is considered an esthetic hallmark, the Brazilian butt lift (BBL) remains controversially discussed in the plastic surgery community. This is due to its contentious safety profile. Thus, informed consent and patient education play a key role in preoperative planning. To this end, we aimed to program an easy-to-use, widely accessible, and low-budget algorithm that produces reliable outcome simulations. METHODS: The conditional generative adversarial network (GAN) was trained using pre- and postoperative images from 1628 BBL patients. To validate outcome simulation, 25 GAN-generated images were assessed deploying 67 Amazon Mechanical Turk Workers (Mturks). RESULTS: Mturks could not differentiate between GAN-generated and real patient images in approximately 49.4% of all trials. CONCLUSION: This study presents a free-to-use, widely accessible, and reliable algorithm to visualize potential surgical outcomes that could potentially be applied in other fields of plastic surgery.

Objectifying the Role of the Depressor Anguli Oris Muscle Using High-Resolution Ultrasound: A Prospective Study.

BACKGROUND: In the setting of facial palsy, synkinesis of the depressor anguli oris (DAO) muscle is a common pathology, impairing dynamic and resting facial symmetry.In this prospective study, the authors used high-resolution ultrasound (HRUS) to evaluate the morphologic features of DAO and to quantify bilateral differences in DAO cross-sectional diameter (CSD) in individuals with unilateral synkinesis. METHODS: From June of 2020 to May of 2021, 30 patients (19 women, 11 men) with clinically diagnosed unilateral synkinesis underwent evaluation with HRUS. DAO CSD was measured bilaterally, 1 cm inferior to the modiolus, in both the resting and smiling positions. RESULTS: The Sunnybrook Facial Grading System Synkinesis Score was 6.20 ± 2.48 (range, 0 to 10). DAO CSD at rest measured 2.41 ± 0.67 mm (range, 1.40 to 4.00 mm) on the control side and 2.66 ± 0.98 mm (range, 1.60 to 5.10 mm) on the affected side. On the control side, DAO CSD was reduced by -0.19 ± 0.43 mm (range, -1.10 to 1.12 mm) during smiling. In contrast, the synkinetic DAO CSD increased by 0.64 ± 0.38 mm (range, 0.00 to 1.59 mm) ( P < 0.001) with animation. The pattern of increased CSD in synkinetic DAO muscles and decreased or unchanged CSD on the control side during smiling was identified in 70% of patients. CONCLUSIONS: HRUS demonstrates increased CSD in synkinetic DAO muscles during active smiling. The opposite is true for DAO muscles on the control side, which exhibit decreased CSD with animation. HRUS can be performed preoperatively to objectify DAO dysfunction and guide targeted therapy. CLINICAL QUESTION/LEVEL OF EVIDENCE: Diagnostic, IV.

The Rise of Facial Palsy on Social Media Over the Last 5 Years.

BACKGROUND: Social media (SoMe) has become a powerful platform for distributing health information. Facial palsy (FP) results in functional and social impairment and lowers quality of life. Social media may help to raise awareness of FP sequalae. This study aims to determine the FP information growth on SoMe platforms and parameters that influence user engagement on FP content. METHODS: Five commonly used SoMe platforms (Facebook, Instagram, TikTok, Twitter, and Reddit) were analyzed. Data on 18 FP hashtags and their social interaction parameters (posts, likes, reaches, comments, shares, language, and country of origin) over the past 5 years (July 31, 2016, to July 31, 2021) were collected. In-depth account analysis was performed on the 5 most popular Instagram profiles associated with FP. RESULTS: The annual growth curve was positive on each platform. Facial Palsy Awareness Week 2021 trended best on TikTok. Facebook accumulated 315,411 likes and 1,922,678 reaches on 8356 posts. On Instagram, 24,968 posts gathered 4,904,124 likes and 9,215,852 reaches. TikTok users interacted on 3565 posts, accumulating 4,304,155 likes and 4,200,368 reaches. The implementation of reels ( P <0.001) and the profile host interacting with their followers by liking ( P <0.001) and replying ( P <0.001) to users' comments significantly increased the engagement rate. CONCLUSIONS: Facial palsy is of increasing interest on SoMe. Facial palsy surgeons may post reels, interact with their community, and engage into FPAW to promote user engagement.

Reply to Nduka et al. Comment on "Kehrer et al. Using High-Resolution Ultrasound to Assess Post-Facial Paralysis Synkinesis-Machine Settings and Technical Aspects for Facial Surgeons. Diagnostics 2022, 12, 1650".

We thank Dr. Nduka et al. for this interesting article [...].

A Ready-to-Use Grading Tool for Facial Palsy Examiners-Automated Grading System in Facial Palsy Patients Made Easy.

BACKGROUND: The grading process in facial palsy (FP) patients is crucial for time- and cost-effective therapy decision-making. The House-Brackmann scale (HBS) represents the most commonly used classification system in FP diagnostics. This study investigated the benefits of linking machine learning (ML) techniques with the HBS. METHODS: Image datasets of 51 patients seen at the Department of Plastic, Hand, and Reconstructive Surgery at the University Hospital Regensburg, Germany, between June 2020 and May 2021, were used to build the neural network. A total of nine facial poses per patient were used to automatically determine the HBS. RESULTS: The algorithm had an accuracy of 98%. The algorithm processed the real patient image series (i.e., nine images per patient) in 112 ms. For optimized accuracy, we found 30 training runs to be the most effective training length. CONCLUSION: We have developed an easy-to-use, time- and cost-efficient algorithm that provides highly accurate automated grading of FP patient images. In combination with our application, the algorithm may facilitate the FP surgeon's clinical workflow.

Towards a Reliable and Rapid Automated Grading System in Facial Palsy Patients: Facial Palsy Surgery Meets Computer Science.

BACKGROUND: Reliable, time- and cost-effective, and clinician-friendly diagnostic tools are cornerstones in facial palsy (FP) patient management. Different automated FP grading systems have been developed but revealed persisting downsides such as insufficient accuracy and cost-intensive hardware. We aimed to overcome these barriers and programmed an automated grading system for FP patients utilizing the House and Brackmann scale (HBS). METHODS: Image datasets of 86 patients seen at the Department of Plastic, Hand, and Reconstructive Surgery at the University Hospital Regensburg, Germany, between June 2017 and May 2021, were used to train the neural network and evaluate its accuracy. Nine facial poses per patient were analyzed by the algorithm. RESULTS: The algorithm showed an accuracy of 100%. Oversampling did not result in altered outcomes, while the direct form displayed superior accuracy levels when compared to the modular classification form (n = 86; 100% vs. 99%). The Early Fusion technique was linked to improved accuracy outcomes in comparison to the Late Fusion and sequential method (n = 86; 100% vs. 96% vs. 97%). CONCLUSIONS: Our automated FP grading system combines high-level accuracy with cost- and time-effectiveness. Our algorithm may accelerate the grading process in FP patients and facilitate the FP surgeon's workflow.

Using High-Resolution Ultrasound to Assess Post-Facial Paralysis Synkinesis-Machine Settings and Technical Aspects for Facial Surgeons.

BACKGROUND: Synkinesis of the facial musculature is a detrimental sequalae in post-paralytic facial palsy (PPFP) patients. Detailed knowledge on the technical requirements and device properties in a high-resolution ultrasound (HRUS) examination is mandatory for a reliable facial muscle assessment in PPFP patients. We therefore aimed to outline the key steps in a HRUS examination and extract an optimized workflow schema. METHODS: From December 2020 to April 2021, 20 patients with unilateral synkinesis underwent HRUS. All HRUS examinations were performed by the first author using US devices with linear multifrequency transducers of 4-18 MHz, including a LOGIQ E9 and a LOGIQ S7 XDclear (GE Healthcare; Milwaukee, WI, USA), as well as Philips Affinity 50G (Philips Health Systems; Eindhoven, the Netherlands). RESULTS: Higher-frequency and multifrequency linear probes ≥15 MHz provided superior imaging qualities. The selection of the preset program Small Parts, Breast or Thyroid was linked with a more detailed contrast of the imaging morphology of facial tissue layers. Frequency (Frq) = 15 MHz, Gain (Gn) = 25-35 db, Depth (D) = 1-1.5 cm, and Focus (F) = 0.5 cm enhanced the image quality and assessability. CONCLUSIONS: An optimized HRUS examination protocol for quantitative and qualitative facial muscle assessments was proposed.

The LRINEC Score-An Indicator for the Course and Prognosis of Necrotizing Fasciitis?

Background: The Laboratory Risk Indicator for Necrotizing Fasciitis score (LRINEC) is a simple tool used to support early diagnosis of Necrotizing Fasciitis (NF). The aim of this study was to investigate whether the LRINEC is suitable as a progression and prognosis parameter in patients with NF. Methods: In this retrospective study, laboratory data of 70 patients with NF were analyzed. The LRINEC was calculated for every patient at the time of hospital admission and postoperatively after surgical interventions. Furthermore, the LRINEC was examined as a prognostic factor for survival. Results: The overall lethality of our series was 20 out of 70 (28.6%). A highly significant LRINEC decrease was found for serial debridements. The largest decrease was observed after the first debridement. There was a significant difference between the initial LRINEC of deceased and surviving patients. A cut off value of >6.5 (7 LRINEC points) resulted in an optimal constellation of sensitivity (70%) and specificity (60%) to predict lethality in patients with NF. Conclusions: The LRINEC significantly decreases after surgical debridement. An initial LRINEC equal or greater than seven is an independent prognostic marker for lethality and can help to identify high-risk patients.

Technical Aspects of High-Resolution Color-Coded Duplex Sonography for the Design of Perforator Flaps.

BACKGROUND: Technical aspects are of utmost significance for an efficient execution in designing perforator flaps with high-resolution color-coded Duplex sonography (CCDS). The following study evaluates decisive factors for a successful microvessel examination conducted by the microsurgeon. METHODS: Technical knowledge presented in this study was based on a series of more than 200 perforator flaps planned with CCDS. Flap reconstructions were performed at the University Hospital Regensburg, Germany, from July 2013 to January 2021. Standard high-resolution ultrasound (US) devices with linear multifrequency transducers of 4 to 18 MHz were used. Modes and device settings were evaluated regarding applicability by microsurgeons. Key steps for safe perforator identification and further optional steps for additional assessment should be discriminated. RESULTS: Different US modes including brightness mode (B-mode), color flow (CF), power Doppler (PD), pulse wave (PW), and blood flow (B-Flow) were used. Transducers from 15 MHz and up were favorable to detect microvessels. Knobology of a standard US device regarding buttons, switches, and specific onscreen options with relevance for perforator mapping was subcategorized in four different groups. For qualitative and quantitative evaluation of microvessels, different US modes were tested with respect to their usefulness.Vital elements of the CCDS exam are disaggregated into three key steps for safe perforator identification and three optional steps for further perforator characterization. A standardized protocol for the CCDS exams was applied. Downregulation of pulse-repetition frequency/scale to adapt device sensitivity to slow-flow velocities represented the most important criterion to visualize microvessels.Qualitative microvessel evaluation was performed in B-mode, CCDS, PD mode, and B-Flow mode. Quantitative assessment was executed using PW-mode and CCDS measuring the microvessels' diameter (mm) and flow characteristics. Quantitative information may be obtained using PW-mode and the distance-measuring tool in CF-mode. CONCLUSION: Technical aspects with respect to proper device trimming and application decisively impact CCDS-guided perforator vessel identification and evaluation.

Simultaneous Fat Injection for Nasal Contouring in Orthognathic Patients.

BACKGROUND: Augmentation rhinoplasty with autologous fat grafting is a useful procedure to meet the demand for facial harmonization in the Asian population. We used this procedure during orthognathic surgery to address inadequate dorsum projection. This prospective study was conducted to determine the fat retention rate in patients undergoing simultaneous autologous fat injection augmentation rhinoplasty and orthognathic surgery. METHODS: Nineteen patients were treated with simultaneous bimaxillary orthognathic surgery and autologous fat grafting of the nasal dorsum and tip. The paired t test was used to compare the nasal volumes before and at least 6 months after surgery measured by 3-dimensional computer tomography scans. All measurements were performed twice by the same evaluator at least 2 weeks apart for intrarater consistency. RESULTS: Seventeen patients completed the study. The volume means before and after surgery were 22.3 ± 4.6 cm3 and 23.3 ± 4.7 cm3, respectively, with a mean difference of 1.0 ± 0.3 cm3 (P < .001). The mean retention rate was calculated to be 50.5% ± 7.0% (range: 40.5%-64.7%). Intrarater consistency was high with a Cronbach α of .97 (P < .001) and .98 (P < .001), respectively. CONCLUSION: This prospective study provides objective graft retention measurements for fat injection augmentation rhinoplasty combined with orthognathic surgery. All patients were satisfied with the results and no complications or additional morbidity was noted in the postoperative course. We consider this procedure to be a safe, reliable, and powerful adjunct to improve the aesthetic results of orthognathic surgery.

"A-PePSI LIGhT" Assessment Score to Predict Pressure Sore Impaired Healing Late Recurrence, Immobility, Greater Surface, Inhibited Thrombocytes.

BACKGROUND: Complication rates of up to 46 percent are reported following pressure sore surgery. Pressure sore patients often exhibit ineffective postoperative wound healing despite tension-free flap coverage, necessitating surgical revision and prolonged hospitalization. Rather than pressure sore recurrence, such impaired healing reflects a failed progress through the physiologic stages of the normal wound-healing cascade. The principal objective of the study reported here was to elucidate potentially modifiable inherent variables that predict predisposition to impaired healing and to provide a tool for identifying cases at risk for complicated early postoperative recovery following pressure sore reconstruction. METHODS: A retrospective chart review of late-stage (stage 3 or higher) sacral and ischial pressure sore patients who underwent flap reconstruction from 2014 to 2019 was performed. A multivariable logistic regression model was used to identify key patient and operative factors predictive of impaired healing. Furthermore, the Assessment Score to Predict Pressure Sore Impaired Healing (A-PePSI) was established based on the identified risk factors. RESULTS: In a cohort of 121 patients, 36 percent exhibited impaired healing. Of these, 34 patients suffered from dehiscences, necessitating surgical revision. Statistically significant risk factors comprising late recurrence (OR, 3.8), immobility (OR, 12.4), greater surface (>5 cm diameter; OR, 7.3), and inhibited thrombocytes (aspirin monotherapy; OR, 5.7) were combined to formulate a prognostic scoring system (A-PePSI LIGhT). CONCLUSIONS: The A-PePSI LIGhT score serves as a prognostic instrument for assessing individual risk for impaired healing in pressure sore patients. Preoperative risk stratification supports rational decision-making regarding operative candidacy, allows evidence-based patient counseling, and supports the implementation of individualized treatment protocols. . CLINICAL QUESTION/LEVEL OF EVIDENCE: Risk, III.

Letter to the Editor: The Case for Publicly Funded Headache Surgery in Germany.

Headache surgery has become a considerable therapeutic option in headache treatment and is of rising interest in the German medical sector. This viewpoint outlines the need for reimbursement of headache surgery in the German healthcare system and demonstrates its cost-effectiveness. Using state-of-the-art patient selection algorithms, the authors found headache surgery to be cost-effective within 7.2 to 6.3 years. Of note, the approach presented is not limited to the German healthcare system.

Microanatomy of the Frontal Branch of the Facial Nerve: The Role of Nerve Caliber and Axonal Capacity.

BACKGROUND: A commonly seen issue in facial palsy patients is brow ptosis caused by paralysis of the frontalis muscle powered by the frontal branch of the facial nerve. Predominantly, static methods are used for correction. Functional restoration concepts include the transfer of the deep temporal branch of the trigeminal nerve and cross-facial nerve grafts. Both techniques can neurotize the original mimic muscles in early cases or power muscle transplants in late cases. Because axonal capacity is particularly important in cross-facial nerve graft procedures, the authors investigated the microanatomical features of the frontal branch to provide the basis for its potential use and to ease intraoperative donor nerve selection. METHODS: Nerve biopsy specimens from 106 fresh-frozen cadaver facial halves were obtained. Histologic processing and digitalization were followed by nerve morphometric analysis and semiautomated axon quantification. RESULTS: The frontal branch showed a median of three fascicles (n = 100; range, one to nine fascicles). A mean axonal capacity of 1191 ± 668 axons (range, 186 to 3539 axons; n = 88) and an average cross-sectional diameter of 1.01 ± 0.26 mm (range, 0.43 to 1.74 mm; n = 67) were noted. In the linear regression model, diameter and axonal capacity demonstrated a positive relation (n = 57; r2 = 0.32; p < 0.001). Based on that equation, a nerve measuring 1 mm is expected to carry 1339 axons. CONCLUSION: The authors' analysis on the microanatomy of the frontal branch could promote clinical use of cross-facial nerve graft procedures in frontalis muscle neurotization and free muscle transplantations.

Do-It-Yourself Preoperative High-Resolution Ultrasound-Guided Flap Design of the Superficial Circumflex Iliac Artery Perforator Flap (SCIP).

The superficial circumflex iliac artery perforator (SCIP) flap is a well-documented, thin, free tissue flap with a minimal donor site morbidity, and has the potential to become the new method for resurfacing moderate-size skin defects. The aim of this study is to describe an easy, reliable, systematic, and standardized approach for preoperative SCIP flap design and perforator characterization, using color-coded duplex sonography (CCDS). A list of customized settings and a straightforward algorithm are presented, which are easily applied by an operator with minimal experience. Specific settings for SCIP flap perforator evaluation were investigated and tested on 12 patients. Deep and superficial superficial circumflex iliac artery (SCIA) branches, along with their corresponding perforators and cutaneous veins, were marked individually with a permanent marker and the anatomy was verified intraoperatively. From this, a simplified procedure for preoperative flap design of the SCIP flap was developed. Branches could be localized and evaluated in all patients. A preoperative structured procedure for ultrasonically guided flap design of the SCIP flap is described. A 100% correlation between the number and emergence points of the branches detected by preoperative CCDS mapping and the intraoperative anatomy was found.

Analysis of Rinsing Fluid during Negative Pressure Wound Therapy with Instillation: A Potential Monitoring Tool in Acute and Chronic Wound Treatment. A Pilot Study.

BACKGROUND: During negative pressure wound therapy (NPWT), open wounds are draped with a nontransparent sponge, making daily wound evaluation impossible. Sometimes, late or undetected bacterial infections and postoperative bleeding result in repetitive surgery, thus prolonging inpatient time. With the introduction of additional fluid instillation (NPWTi), the wound surface is rinsed, and bacteria, proteins and biomarkers are flushed into a collecting canister, which is later discarded. METHODS: The aim of this pilot study was to analyze rinsing fluid samples (0.9% sodium chloride) from the NPWTi device in patients with acute and chronic wounds. In 31 consecutive patients a standardized laboratory analysis was performed to evaluate cellular composition and potassium, phosphate, lactate dehydrooxygenase, pH and total protein levels. RESULTS: While there was an increase in the total cellular amount and the number of polymorphonuclear cells, the number of red blood cells (RBC) decreased after surgery. Potassium and pH showed no significant changes in the first three postoperative days, whereas total protein showed an undulant and partially significant course. CONCLUSION: We were able to quantify cellular metabolites by analyzing the rinsing fluid of NPWTi. We propose the analysis of this material as a novel and potentially promising tool to monitor wound status without removal of the dressing. The establishment of reference values might help to improve the NPWTi therapy.