Reverse blood flow as an option in mandibular reconstruction using a two-segment fibula free flap.

Microsurgical reconstruction is currently considered a method of choice for the repair of soft tissue or bony defects in head and neck surgery. This technical note presents the use of a reverse flow technique in mandibular reconstruction with two segments of fibula free flap in a patient with bilateral pseudoarthrosis. In the standard procedure, both segments of the fibula are supplied by one donor vascular pedicle with normal antegrade blood flow. The approach presented here employs reverse flow in the distal segment of the fibula using a venous graft to create two vascular independent free fibula segments. Reverse flow in mandibular reconstruction represents an alternative option to support the success of microsurgical procedures in indicated cases.

Changes in gene expression in pressure ulcers debrided by different approaches - a pilot study.

Pressure ulcers (PUs), also known as pressure injuries, are chronic wounds that represent potential lifelong complications. Pressure ulcers of a deep category (III and IV) are often indicated for surgical treatment - debridement and surgical reconstruction. Sharp surgical debridement is widely used in the debridement of PUs; however, the Versajet® hydrosurgery system is becoming an increasingly popular tool for tangential excision in surgery due to its numerous advantages. This work focused on the expression of selected genes, especially those associated with oxidative stress, in PUs debrided by two approaches - sharp surgical debridement and debridement using Versajet® hydrosurgery system. Expression of following genes was evaluated: NFE2L2, ACTA2, NFKB1, VEGFA, MKI67, HMOX1, HMOX2, HIF1A, and SOD2. ACTB and PSMB were used as housekeeping genes. So far, five patients have been enrolled in the study. Preliminary results suggest no significant difference in gene expression with different pressure ulcer treatment approaches except NFE2L2, despite the macroscopic differences. However, the results revealed correlations between the expression of some genes, namely HIF1A and SOD2, VEGFA and SOD2 and VEGFA and HIF1A. These results may indicate a connection between hypoxia, oxidative stress, pressure ulcer healing processes and angiogenesis.

RECONSTRUCTION OF DEEP HEAD BURN WITH A FREE FLAP - A CASE REPORT.

Third degree burn trauma of the head and neck requires an interdisciplinary approach. After emergency care and hemodynamic stabilization of the patient the focus lies on the reconstruction of the damaged tissue. The options of reconstruction are influenced by the general condition of the patient and by the condition of the surrounding tissues. The deep defects of the head are dangerous for a high risk of wound infection and possible fatal complications. In particular cases the first methods of choice for closure of the defect may be ineffective and a free flap transfer should be considered. We present a case report of a 62-year-old woman who suffered third degree burn trauma of the head and neck leading to a deep defect of the forehead reaching behind the hairline. On the bottom there was an exposed bone with no healing tendency. Due to surrounding fragile scarred tissue we chose a free flap transfer using serratus anterior muscle as a method of closure. The flap was fully healed and provided good aesthetic and functional outcome.

INTRAOPERATIVE FAT GRAFTING INTO THE PECTORALIS AND LATISSIMUS DORSI MUSCLES-NOVEL MODIFICATION OF AUTOLOGOUS BREAST RECONSTRUCTION WITH EXTENDED LATISSIMUS DORSI FLAP.

BACKGROUND: The latissimus dorsi flap is a reliable and one of the most commonly used methods of both immediate and delayed breast reconstruction. Its disadvantage is the limited volume of transferred tissue. The authors present their experience with the use of extended latissimus dorsi flap associated with immediate fat grafting into the pectoralis and latissimus dorsi muscles for secondary breast reconstruction. METHODS: From 2013 to 2016, 14 patients underwent secondary unilateral total breast reconstruction with extended latissimus dorsi flap associated with primary fat grafting into the pectoralis major and latissimus dorsi muscles. Fat was injected under visual control between muscle fibers. Fat injected into the pectoralis muscle formed an apparent bulging - autoprosthesis. RESULTS: Mean patient age was 48.2 years (range, 34 to 64 years). Mean injected fat volume was 86.4 ml (range, 50 to 160 ml) and majority of this volume was injected into the pectoralis muscle. All flaps healed uneventfully and no fat grafting-related complications were observed. The most common complication was donor site seroma, which occurred in 57.1%. Results of postoperative ultrasound examination were evaluated. Incidence and the size of oil cysts and fat necroses were significantly lower in muscular layer in comparison with the subcutaneous layer of the reconstructed breast. CONCLUSIONS: Immediate fat transfer into the pectoralis and latissimus dorsi muscle increases the breast volume during the reconstruction with extended latissimus dorsi flap avoiding implant-related complications when abdominal tissue is not available. Pectoralis and latissimus dorsi muscles were shown as reliable and safe recipients for fat grafting.

Relationship between cardioventilatory coupling and pulmonary gas exchange.

Cardioventilatory coupling (CVC) is a temporal alignment between the heartbeat and inspiratory activity caused by pulsatile baroreceptor afferent activity. However, although first described over a century ago, the functional significance of CVC has yet to be established. One hypothesis is that baroreceptor triggering of inspiration positions heartbeats into phases of the respiratory cycle that may optimize pulmonary gas exchange efficiency. To test this hypothesis, we recruited ten patients with permanently implanted fixed-rate cardiac pacemakers and instructed them to pace breathe at heart rate-to-respiratory rate (HR/f) ratios of 3·8, 4·0 and 4·2. This breathing protocol enabled us to simulate heartbeat distributions similar to those seen in the presence (4·0) and complete absence (3·8, 4·2) of CVC. Results showed that heart rate, mean arterial pressure, end-tidal carbon dioxide and tidal volume remained unchanged across the three conditions (P> 0·05). Pulmonary gas exchange efficiency, as determined by the ventilatory equivalents of carbon dioxide (V·E/V·CO2) and oxygen (V·E/V·O2) did not differ significantly by HR/f ratio (P = 0·29 and P = 0·70, respectively). These data suggest that CVC does not play a significant role in optimizing pulmonary gas exchange efficiency in humans.

Neurovascular coupling and distribution of cerebral blood flow during exercise.

We examined how cerebral blood flow velocity (CBV) and neurovascular coupling is influenced by exercise. Blood velocities in the posterior and middle cerebral arteries (PCAv and MCAv) during rest and cycling exercise at 60% estimated maximal oxygen consumption were measured. Neurovascular coupling was quantified as the ΔPCAv with visual stimulation. During exercise, despite a 15.2±13.6% and 26.1±22.5% increase from rest in the MCAv and PCAv, respectively, neurovascular coupling was unaltered. Thus, despite regionally heterogeneous elevations in CBV during exercise, neurometabolic coupling is maintained.

Respiratory sinus arrhythmia in conscious humans during spontaneous respiration.

Respiratory sinus arrhythmia (RSA) is the beat-to-beat fluctuation in heart rate at the frequency of the respiratory cycle. While it is common to study RSA under conditions of controlled breathing, where respiratory frequency, and sometimes tidal volume and inspiratory:expiratory ratio are controlled, the effect of controlled breathing on RSA is not clear. While not all studies exploring the effects of controlled breathing on RSA magnitude are consistent, some of the best-designed studies addressing this question did find a significant effect. In addition to respiratory timing influencing heartbeats, there is evidence that cardiac timing also influences respiratory timing, termed cardioventilatory coupling. Thus, the timing interactions between the cardiac and respiratory systems are complex, and bi-directional. Controlled breathing eliminates one aspect of this relationship, and studies designed to understand cardiorespiratory physiology conducted under these conditions need to be interpreted with an understanding that they may not represent normal physiology.

Influence of breathing frequency on the pattern of respiratory sinus arrhythmia and blood pressure: old questions revisited.

Respiratory sinus arrhythmia (RSA) is classically described as a vagally mediated increase and decrease in heart rate concurrent with inspiration and expiration, respectively. However, although breathing frequency is known to alter this temporal relationship, the precise nature of this phase dependency and its relationship to blood pressure remains unclear. In 16 subjects we systematically examined the temporal relationships between respiration, RSA, and blood pressure by graphically portraying cardiac interval (R-R) and systolic blood pressure (SBP) variations as a function of the respiratory cycle (pattern analysis), during incremental stepwise paced breathing. The principal findings were 1) the time interval between R-R maximum and expiration onset remained the same ( approximately 2.5-3.0 s) irrespective of breathing frequency (P = 0.10), whereas R-R minimum progressively shifted from expiratory onset into midinspiration with slower breathing (P < 0.0001); 2) there is a clear qualitative distinction between pre- versus postinspiratory cardiac acceleration during slow (0.10 Hz) but not fast (0.20 Hz) breathing; 3) the time interval from inspiration onset to SBP minimum (P = 0.16) and from expiration onset to SBP maximum (P = 0.26) remained unchanged across breathing frequencies; 4) SBP maximum and R-R maximum maintained an unchanged temporal alignment of approximately 1.1 s irrespective of breathing frequency (P = 0.84), whereas the alignment between SBP minimum and R-R minimum was inconstant (P > 0.0001); and 5) beta(1)-adrenergic blockade did not influence the respiration-RSA relationships or distinct RSA patterns observed during slow breathing, suggesting that temporal dependencies associated with alterations in breathing frequency are unrelated to cardiac sympathetic modulation. Collectively, these results illustrate nonlinear respiration-RSA-blood pressure relationships that may yield new insights to the fundamental mechanism of RSA in humans.

Evaluation and comparison of composite and split-thickness skin grafts using cutometer mpa 580.

BACKGROUND: In our preliminary experiments we found that composite skin grafts consisting of allogeneic acellular dermis and thin epidermal autologous grafts applied to the excised burn wound in one stage led to better results in terms of viscoelastic properties than autologous split-thickness skin grafts. PATIENTS AND METHODS: In ten burn patients we applied composite skin grafts consisting of allogeneic acellular dermis and thin epidermal autologous grafts and followed the quality of the reconstructed skin cover with a special device, Cutometer MPA 580, over a period of four years. RESULTS: The cutometric curves demonstrated better viscoelastic properties in composite skin grafts than in conventional split-thickness skin grafts after four years. We found Cutometer MPA 580 to be an advantageous device for the objectification of improved quality of reconstructed skin cover. DISCUSSION: Among the various methods the cutometer showed the advantage of being a non-invasive, precise, and objective method of measuring skin's viscoelastic properties. The Vancouver Scar Score is a subjective evaluation of skin viscoelasticity. CONCLUSION: Our prospective clinical study clearly demonstrated that cutometric measurement produced objective results in contrast to clinical evaluation, the Vancouver Scar Score, and other non-quantitative methods. Our hypothesis that composite skin grafts consisting of allogeneic acellular dermis and thin epidermal autologous grafts applied onto the excised burn wound in one stage led to better results in terms of viscoelastic properties than autologous split-thickness skin grafts was fully confirmed.

Respiratory modulation of cardiovagal baroreflex sensitivity.

Emerging evidence has suggested that with minimal prerequisite training, slow deep breathing around 0.10 Hz can acutely enhance cardiovagal baroreflex sensitivity (BRS) in humans. Such reports have led to the speculation that behavioral interventions designed to reduce breathing frequency may serve a therapeutic role in ameliorating depressed baroreflex function in conditions such as chronic heart failure, essential hypertension, and obstructive airway disease. This study sought to test the hypothesis that slow controlled breathing acutely enhances cardiovagal baroreflex function in young healthy volunteers. Distinct from earlier studies, however, baroreflex function was examined (n = 30) using the classical pharmacological modified Oxford method, which enabled the assessment of cardiovagal BRS through experimentally driven baroreceptor stimulation across a wide range of blood pressures. For a comparison against existing evidence, spontaneous cardiovagal BRS was also assessed using the alpha-index and sequence method. Compared with fast breathing (0.25 Hz), slow breathing (0.10 Hz) was associated with an increase in the alpha-index (8.1 +/- 14 ms/mmHg, P < 0.01) and spontaneous up-sequence BRS (10 +/- 11 ms/mmHg, P < 0.01). In contrast, BRS derived from spontaneous down sequences and the modified Oxford method were unaltered by slow breathing. The lack of change in BRS derived from the modified Oxford method challenges the concept that slow breathing acutely augments arterial baroreflex function in otherwise healthy humans. Our results also provide further evidence that spontaneous BRS may not reflect the BRS determined by experimentally driven baroreceptor stimulation.

Human sinus arrhythmia: inconsistencies of a teleological hypothesis.

Respiratory sinus arrhythmia (RSA) may serve an inherent function in optimizing pulmonary gas exchange efficiency via clustering and scattering of heart beats during the inspiratory and expiratory phases of the respiratory cycle. This study sought to determine whether physiological levels of RSA, enhanced by slow paced breathing, caused more heart beats to cluster in inspiration. In 12 human subjects, we analyzed the histogram distribution of heart beats throughout the respiratory cycle during paced breathing at 12, 9, and 6 breaths/min (br/min). The inspiratory period-to-respiratory period ratio was fixed at approximately 0.5. RSA and its relationship with respiration was characterized in the phase domain by average cubic-spline interpolation of electrocardiographic R wave-to-R wave interval fluctuations throughout all respiratory cycles. Although 6 br/min breathing was associated with a significant increase in RSA amplitude (P < 0.01), we observed no significant increase in the proportion of heart beats in inspiration (P = 0.34). Contrary to assumptions in the literature, we observed no significant clustering of heart beats even with high levels of RSA enhanced by slow breathing. The results of this study do not support the hypothesis that RSA optimizes pulmonary gas exchange efficiency via clustering of heart beats in inspiration.

Cutometrical measurement confirms the efficacy of the composite skin grafting using allogeneic acellular dermis in burns.

Measurement of viscoelasticity of the skin using the device called cutometer seems to be a very precise and promising diagnostic method in different skin pathologies. However, only a very limited number of reports dealing with the use of cutometer in burns is available. The composite skin grafting using an allogeneic acellular dermis covered with a thin epidermal autologous graft is supposed to improve viscoelastic properties of grafted skin in full-thickness burns. Cutometer MPA 580 has been used for examination of healthy skin, healed and maturated autologous split-thickness skin grafts, and in two patiens 6 years after composite skin grafting using the allogeneic acellular dermis + thin autologous epidermal graft in one stage. Typical curves defined by values of R0-R9 parameters are presented. These data document significantly better viscoelastic properties of composite skin grafts than those of conventional split-thickness skin grafts after 6 years. Measurements of viscoelasticity of the skin, using a cutometer, will probably bring useful and precise data for evaluation of the reconstructed skin in burns. Significantly better properties of the composite skin graft were assessed clinically and measured by Cutometer MPA 580 6 years after surgery.