[Choice of flaps for phalloplasty: what is the contemporary standard? Consensus Statement of the German-Speaking Society for Microsurgery of Peripheral Nerves and Vessels]. / "Wahl der Lappenplastik zur Phalloplastik ­ was ist zeitgemäßer Standard" ­ Konsensus-Bericht der deutschsprachigen Arbeitsgemeinschaft für Mikrochirurgie der peripheren Nerven und Gefäße.

The ever-expanding number of transmen as well as their surgeons share an increasing interest in the construction of a neophallus. While the indication for surgery and the positive effect of a phalloplasty on the quality of life, mental health and sexual function has already been thoroughly analysed, there is a lack of data comparing and evaluating the surgical steps. During the consensus conference on the "choice of flaps for phalloplasty" at the annual meeting of the German-Speaking Society for Microsurgery of Peripheral Nerves and Vessels, the current literature was discussed and a consensus on the surgical technique of a phalloplasty was reached. This manuscript publishes jointly developed recommendations on the following topics: choice of flaps for phalloplasty, preoperative diagnostic tests before phalloplasty, urethral construction in the radial forearm flap and anterior lateral thigh flap, preformation of the urethra at the forearm or thigh, venous drainage of the radial forearm flap, innervation of the phallus, staged phalloplasty, coronaplasty and managing the donor site of a radial forearm flap.

Isolation and culture of different epidermal and dermal cell types from human scalp suitable for the development of a therapeutical cell spray.

BACKGROUND: Previous studies demonstrated, that cultured epithelial autografts (CEA) can be isolated and skin cell sprays can be produced for application on different types of wounds. The purpose of the present study was to determine which cell types can be isolated from the human scalp and whether these cells can be used for spray transplantation. METHODS: Outer root sheath cells (ORS), keratinocytes, melanocytes, dermal papilla cells (DP), and dermal sheath cells (DSC) were isolated from human scalp tissue. Isolated cells were characterized, expanded and sprayed in an in vitro model. Growth behaviour, morphology and cell counts were compared with non-sprayed cells. RESULTS: With acceptable time, equipment and laboratory personnel a sufficient amount of keratinocytes, ORS, melanocytes, DP cells and DSC cells could be achieved. The cells are sufficient for application as a cell spray. Cells, positive for Integrin alpha6, Cytokeratin 19, CD73 and CD105 were identified within the cultures. CONCLUSIONS: Human scalp is suitable to gain epidermal and dermal cells for the development of therapeutic cell spray transplantation. Further studies have to determine, whether these cells can be combined to produce wound specific skin substitutes.

Dose-dependent effects of a nitric oxide donor in a rat flap model.

Previous studies have proven the effectiveness of nitric oxide (NO) donors to enhance flap survival in experimental models. The purpose of this study was to determine the ideal dose of the NO donor spermine/nitric oxide complex (Sper/NO) with respect to flap survival and hemodynamic side effects. Additionally, the influence of the type of application (systemically versus intra-arterial into the flap artery) was observed.Seventy-two male Wistar rats were divided into 9 experimental groups. An extended epigastric adipocutaneous flap (6 x 10 cm) based on the left superficial epigastric artery and vein was raised in each animal. The average percentage of flap necrosis was 69.8% in the control group with ischemia and 29.8% in the non ischemic controls. The average necrosis areas in the 3 groups after preischemic intravenous (i.v.) application of Sper/NO (250, 500, and 750 nmol/kg body weight) were 63.5%, 33.8%, and 38.4%, respectively. The application of similar doses into the flap artery resulted in 63.5%, 72.3%, and 64.3% flap necrosis; 52.7% average flap loss was observed in an additional group receiving Sper/NO adjusted to flap weight (500 nmol/kg flap weight). Only the intravenous application of 500 and 750 nmol/kg resulted in a significant reduction of flap necrosis compared with the ischemic controls (P < 0.01). The drop in mean arterial pressure was less after i.v. application of 500 nmol/kg Sper/NO compared with 750 nmol. Our data show that the preischemic intravenous application of 500 nmol/kg Sper/NO achieved the best results with acceptable side effects. A dose of 250 nmol/kg i.v., as well as the application of Sper/NO into the flap artery, was demonstrated to be ineffective.

Sprayed cultured epithelial autografts for deep dermal burns of the face and neck.

The objective of this study was the assessment of clinical results after sprayed application of cultured epithelial autograft (CEA) suspensions onto deep dermal burn wounds of the face and neck. Nineteen patients with deep dermal burns of the face and neck were included into a prospective study. The average total body surface area burn was 15.1% (7%-46%; median: 13%). The average Abbreviated Burn Severity Index (ABSI) was 6.7 points (4-12 points; median: 7 points). The application of sprayed CEA suspension was performed onto an average body surface area of 2% (0.5-5%; median: 2%). Thirteen patients were recruited for clinical follow-up after an average of 10 months (3-18 months). The average Vancouver Scar Scale score at follow-up was 2.4 +/- 2.2 points (range, 0-8 points), and the average Donnersmarck and Hörbrand score was 9.3 +/- 6.8 points (range, 0-22). Four patients had less than 9 months' follow-up. Excluding these patients from the analysis resulted in an average Vancouver Scar Scale score of 1.3 +/- 0.9 points (range, 0-3 points) and an average Donnersmarck and Hörbrand score of 8.0 +/- 7.4 points (range 0-22) for the remaining 9 patients.Our data show that enzymatic and careful surgical debridement and consecutive application of CEA suspensions using a spray technique results in excellent cosmetic outcomes compared with any other method.

Does chemotherapy impair the bone healing and biomechanical stability of vascularized rib and fibula grafts?

The purpose of this study was to observe the impact of chemotherapy on the healing and biomechanical properties of vascularized bone grafts. Ten male beagle dogs were divided into two experimental groups: a chemotherapy group (CH) and control group (C). Group CH received adjuvant and neo-adjuvant chemotherapy. Each animal of both groups underwent the following operative procedures. The 5th and 7th rib were removed and replaced by vascularized pedicle transfers of the adjacent 4th and 8th rib. Additionally, a free fibular flap was elevated and retransferred to the same anatomic position. The rate of bony union on plain x-ray was 100 percent in group C, 30 percent in the vascularized rib, and 80 percent in the fibula grafts of group CH. Microangiography demonstrated no avascular bone segments in group C and in the fibula flaps of group CH. The vascularized ribs of group CH presented with 20 percent avascular bone segments. Biomechanical tests focusing on the durability of the vascularized grafts against bending and torsion forces demonstrated a reduction of the average maximum bending times by 17 percent and 23.9 percent compared to the controls ( P < 0.05). The twisting times were reduced by 13.8 percent (n.s.) and 32.5 percent ( P < 0.05). The data demonstrated a clear worsening in bone healing and stability after simulated adjuvant and neo-adjuvant chemotherapy. Thus, a large animal model was established for the further determination of the effects of chemotherapy on different vascularized bone transfers.

Versatility of vertical rectus abdominis musculocutaneous flaps.

The purpose of the study was to demonstrate a variety of indications for the vertical rectus abdominis musculocutaneous (VRAM) flap with respect to donor-site morbidity and alternative procedures. Fifteen VRAM flaps were performed in 15 patients during a 4-year period. The average age of patients was 58 years (range, 34-76 years). Inferiorly based VRAM flaps were used for defect coverage after tumor resection and for penile reconstruction in 7 cases. Superiorly based VRAM flaps were performed in 7 cases for reconstruction of osteocutaneous defects following sternal osteomyelitis and tumor resection. Arterial and venous "supercharging" was necessary in one case. One free VRAM flap was performed in a patient suffering from an osteocutaneous defect after resection of a malignant melanoma metastasis with infiltration of the brain and skull. The reconstructive goals were achieved in all cases using VRAM flap procedures. No total flap loss occurred. Minor complications as well as abdominal wall bulging and hernias were observed in four cases. The pedicled VRAM flap provides a reliable tool for coverage of large soft-tissue defects of the chest wall, groin, hip, and perineum even in a high-risk population, in which a safe and fast forward flap procedure is the primary reconstructive goal. Arterial and/or venous supercharging may be necessary, particularly in superiorly based VRAM flaps. An inferiorly based VRAM flap is a reliable tool for phalloplasty under special circumstances. The indication for free VRAM flaps is given in rare clinical situations. Stabilization of the donor site using artificial mesh is highly recommended.

Impact of radiation therapy on healing and stability of vascularized bone grafts in a dog model.

The purpose of the study was to observe the impact of radiation therapy on healing and biomechanical properties of vascularized bone grafts, and thus to establish an appropriate large animal model. Ten male beagles were divided into two experimental groups: radiation (R) and control (C). The left 5th to 7th ribs of the animals of group R were irradiated 3 and 2 weeks preoperatively, using a dose of 8 Gy each time. Each animal of both groups underwent the following operative procedures. The 5th and 7th ribs were removed, and the 5th rib was replaced by a vascularized pedicle transfer of the 4th rib. The 7th rib was reconstructed using a pedicle transplant of the 8th rib. The 5th and 7th ribs were used as nonvascularized bone grafts to replace the donor sites of the 4th and 8th ribs, respectively. Group R received two further irradiation cycles 2 and 3 weeks postoperatively. The vascularized rib grafts of group R demonstrated a higher number of delayed unions in plain x-rays and avascular bone segments in microangiography than the control group. The presence of vital osteocytes in histology was not significantly different between groups. Biomechanical tests focusing on the durability of vascularized ribs against bending and torsion forces demonstrated a reduction of average maximum bending moments by 56.6% after radiation compared to controls (P < 0.05). Twisting moments were reduced by 47.6% (P < 0.05). The data demonstrate a significant worsening in bone healing and stability after pre- and postoperative radiation therapy to the wound bed and bone grafts. Thus, a large animal model is established for further determination of different strategies of radiotherapy in combination with vascularized bone transfers.

Correlations between cardiac output, stroke volume, central venous pressure, intra-abdominal pressure and total circulating blood volume in resuscitation of major burns.

The purpose of this study was to observe the interactions between cardiac index (CI), stroke volume index (SVI), central venous pressure (CVP), intra-abdominal pressure (IAP) and total circulating blood volume index (TBVI) during resuscitation of major burns. Sixteen patients with an average TBSA of 46% (26-67%) and an average abbreviated burn severity index of 8.9 (7-11) were included into an intra-individual comparative prospective study over an 18-month period. The COLD Z-021 system (Pulsion Medical Systems, Munich, Germany) was used to obtain CI, SVI and TBVI. Two hundred and thirty-four to 278 intra-individually comparative measurements were performed for the analyses during the first 4 days after the burn injury. Correlations were shown for the interactions between CI and TBVI (r = 0.550; rs = 0.518), SVI and TBVI (r = 0.606; rs = 0.626) and for CVP versus IAP (r = 0.487; rs = 0.474). Poor or no correlations were demonstrated for the comparisons CI versus CVP (r = 0.401; rs = 0.352), CVP-PEEP versus IAP (r = 0.255; rs = 0.272). TBVI versus IAP (r = -0.120; rs = -0.169), TBVI versus CVP (r = 0.025; rs = -0.036), TBVI versus CVP-PEEP (r = -0.046; rs = -0.101), CI versus CVP-PEEP (r = 0.088; rs = 0.092) as well as for IAP versus CI (r = 0.050; rs = 0.034). An additional analysis demonstrated no correlation between TBVI and MAP (r = -0.095; rs = -0.136). Our data provide evidence that the CVP is influenced more by external pressures (IAP) than by the actual intravascular volume status of the patient. Thus, the CVP is not a suitable tool to guide fluid resuscitation during burns with shock. The TBVI may be an ideal value to guide resuscitation because the augmentation of TBVI during fluid resuscitation correlated well with improved cardiac output and stroke volume. Future randomised studies are required to demonstrate whether TBVI guided resuscitation of burns has an impact on outcome.

Measures to prevent complications of distally based neurovascular sural flaps.

Several publications in recent years have proven unbroken popularity of superficial sural artery flaps for the coverage of defects of the lower leg and proximal foot. However, complications are being discussed rarely. The realistic complication rate is up to 59%, given corresponding comorbidities, risk factors, or performance errors. Twelve distally based neurovascular sural flaps were used for reconstruction of heel, ankle, and lower-leg defects between 2003 and 2005. The following pre- and postoperative procedures were performed as a routine: An additional arteriography was done preoperatively to prove the patency of the peroneal artery. Acoustic Doppler ultrasound was used to identify the lesser saphenous vein and the concomitant vessels (perforators of the peroneal artery) of the sural nerve. An enlarged skin paddle with a tail of skin over the pedicle at the point of rotation was harvested intraoperatively to take pressure off the vessels and facilitate primary closure. Postoperatively, external fixation provides strict immobilization of the affected leg. Following these measures, no flap loss was observed in the presented series, and only few minor complications occurred.

Skin cell isolation and expansion for cell transplantation is limited in patients using tobacco, alcohol, or are exhibiting diabetes mellitus.

The aim of this exploratory study was to investigate the isolation and expansion of keratinocytes and fibroblasts from donors with certain medical histories. Biopsies were taken from donors (N=32) falling into one or more of the following categories: a history of heavy smoking and/or alcohol abuse, drug abuse, diabetes mellitus or steroid treatment. Cells from donors who did not fall into any of the above-mentioned categories were used as controls. Proliferation and growth behaviour of cells were analyzed by measurement of passage duration, absorbance (MTT-assay) and light microscopy. Donors with a specific medical history required larger biopsy areas than the control group for isolating a sufficient number of fibroblasts and keratinocytes. Times to confluence were significantly prolonged and absorbances (MTT) were significantly reduced in several donor groups when compared to control cultures. Biopsies from donors with steroid treatment, drug abuse and combined nicotine and alcohol abuse could not be established beyond passage 0 degrees or 1 degree, respectively. We conclude that isolation and expansion of skin cells from donors with certain medical histories may require larger biopsies, prolonged expansion times or may even result in failure. These findings may therefore be of clinical importance in the field of autologous skin cell transplantation.

Remote ischemic preconditioning of flaps: a review.

Ischemic preconditioning (IP) is defined as a brief period of ischemia ("preclamping") followed by tissue reperfusion, thereby increasing ischemic tolerance for a subsequent longer ischemic period. Several studies showed the effectiveness of classic local IP by preclamping the flap pedicle. There are two temporally and mechanically different types of IP: acute preconditioning, which is induced by preclamping the flap pedicle briefly before flap ischemia, and late preconditioning, induced by a preclamping procedure 24-48 h before flap ischemia. However, both types of local ischemic preconditioning are rarely used clinically, most likely since they can be applied only by invasive means, significantly increase operation time, or even require a second surgical procedure. Several studies from our laboratory showed, in different experimental models, that acute IP, enhancement of flap survival, and improvement of reperfusion microcirculation can be achieved not only by preclamping the flap pedicle, but also by induction of an ischemia/reperfusion event in a body area distant from the flap prior to elevation. This new acute remote IP procedure can be applied without invasive means, using limb tourniquet ischemia briefly before flap ischemia. The effectiveness of acute remote IP was confirmed by other authors in large animal models. Another of our studies showed that late remote IP using a limb tourniquet 24 h before flap ischemia attenuates ischemia/reperfusion in muscle flaps, whereas it was ineffective in adipocutaneous flaps. The exact mechanism of "classic" as well as remote IP is not yet finally determined, although several studies demonstrated that endogenous nitric oxide plays an important role. In summary, the use of a tourniquet to induce limb ischemia before flap ischemia could provide a new, alternative, noninvasive remote IP protocol, although late remote IP might be effective only in muscle flaps. However, the possible future clinical application for late IP is elective flap surgery, whereas acute remote IP could even be used in emergency flaps.

Late remote ischemic preconditioning in rat muscle and adipocutaneous flap models.

The purpose of this study was to determine whether remote ischemic preconditioning can be induced by a late mechanism. The rat cremaster flap model was used for assessment of ischemia-reperfusion injury. In the control group (N = 9), 2 hours of flap ischemia was induced after preparation of the cremaster muscle. Ten minutes of ischemia of the contralateral hind limb was induced 24 hours before flap ischemia in the late remote ischemic preconditioning group (LRIP) (N = 8). In vivo microscopy was performed after 1 hour of flap reperfusion in each animal. The epigastric adipocutaneous flap model was used for the second part of the experiment. Three hours of flap ischemia was induced in the control group (N = 8). A similar late remote ischemic preconditioning protocol as in the LRIP group was used for the second late remote ischemic preconditioning group (N = 8). A significantly higher muscle red blood cell velocity in the capillaries, first-order arterioles, and venules, and a higher capillary flow as well as a decreased number of "stickers" were observed in the late remote ischemic preconditioning group compared with the first control group (p < 0.05). Average flap necrotic area was not significantly different within the second control group and the second late remote ischemic preconditioning group in the adipocutaneous flaps. These data show that late remote ischemic preconditioning attenuates ischemia-reperfusion injury in muscle flaps, whereas it is ineffective in adipocutaneous flaps.

Transcardiopulmonary thermal dye versus single thermodilution methods for assessment of intrathoracic blood volume and extravascular lung water in major burn resuscitation.

The purpose of this study was to compare the approximated values for intrathoracic blood volume (ITBV) and extravascular lung water (EVLW) obtained from a single indicator dilution to the exact data measured by double-indicator dilution. Eighteen patients with an average TBSA of 46.3% (range, 26 to 67%) and an average abbreviated burn severity index of 8.7 (range, 7 to 11) were included into a intraindividual comparative prospective study over a 20-month period. The COLD Z-021 system (Pulsion Medical Systems, Munich, Germany) was used to obtain both the exact measurements, as well as the estimated values for ITBV and EVLW. Two hundred ninety intraindividually comparative measurements were performed during the first 4 days after the burn injury. A good correlation between both techniques was shown for ITBVI (0.77; P <.01) for the overall measurements. However, the overall bias demonstrated a standard deviation higher than the mean value (-87.4 +/- 136 ml/m2), and precision for the estimated values for ITBVI was poor (-491 to 783 ml/m2). Additional analyses demonstrated a poor but significant correlation for low states of ITBV (r =.37; P <.01), but no significant correlations were found between the techniques for normal and high ITBV states. Thus, the approximated ITBV obtained from single thermodilution should not be used to guide volume therapy in major burn resuscitation. Furthermore, the EVLW is neither suitable for diagnostic use nor for therapeutic decisions because it is calculated on the basis of the poorly estimated values for ITBV in single thermodilution. Transcardiopulmonary single thermodilution is not suitable to assess intrathoracic blood volume and extravascular lung water in burn shock. However, the method is suitable to assess cardiac output and its derived parameters in burn resuscitation as shown in previous studies. It still must be proven whether the exactly measured ITBV obtained from transcardiopulmonary double-indicator dilution is superior to the commonly used parameters to guide major burn resuscitation.

Role of nitric oxide in the mechanism of preclamping and remote ischemic preconditioning of adipocutaneous flaps in a rat model.

The purpose of this study was to determine whether nitric oxide (NO) plays a role in the mechanism of acute ischemic preconditioning (IP). Fifty-eight male Wistar rats were divided into seven experimental groups. An extended epigastric flap was raised in one of the control groups (C, n = 8), and a 3-hr flap ischemia was induced. Another group served as a non-ischemic control (CO, n = 8). The animals of group S (n = 9) received 500 nmol/kg of Spermine/Nitric Oxide Complex (Sper/NO) intravenously 30 min prior to ischemia. The group N+P (L-NAME + preclamping, n = 8) received 10 mg/kg Nomega-Nitro-L-Arginine Methyl Ester (L-NAME) intravenously before preclamping of the flap pedicle (10-min cycle length, 30-min reperfusion). Ten mg/kg L-NAME were administered in group N+T (L-NAME + tourniquet, n = 9) before ischemia of the right hindlimb was induced using a tourniquet for 10 min after flap elevation. Flap ischemia was induced after 30 min of limb reperfusion. A similar protocol was used in the groups N+P+S (L-NAME + preclamping+Sper/NO, n = 8) and N+T+S (L-NAME + tourniquet + Sper/NO, n = 8). In both groups Sper/NO was administered 30 min prior to flap ischemia, additionally to the protocol of the groups N+P and N+T. Mean flap necrosis area was assessed on the fifth postoperative day using a planimetry software. Average flap necrosis area was 67 +/- 16 percent in the control group C, 28 +/- 13.3 percent in the non-ischemic controls (CO), 10 +/- 5.9 percent in group S, 77.5 +/- 10.2 percent in group N+P, 76 +/- 6.9 percent in group N+T, 71.5 +/- 9.4 percent in group N+P+S, and 78 +/- 9.9 percent in group N+T+S. The animals of group S and CO demonstrated a significantly lower area of flap necrosis than all other groups ( p < 0.001). No significant difference could be shown between the groups C, N+P, N+T, N+P+S and N+T+S. Group S showed a significantly lower flap necrosis area than group CO ( p < 0.01). The data showed, that NO plays an important role in the mechanism of IP since the administration of an NO-donor previous to ischemia simulates the effect of IP, while the unspecific blocking of NO synthesis by L-NAME eliminates the protective effect of flap preconditioning by preclamping as well as by remote IP. Exogenous NO application is insufficient to provide protection once the endogenous NO synthesis is blocked.

Acute remote ischemic preconditioning on a rat cremasteric muscle flap model.

A previous study showed, in a rat adipocutaneous flap model, that acute ischemic preconditioning (IP) can be achieved not only by preclamping of the flap pedicle, but also by a brief extremity ischemia prior to flap ischemia. The purpose of this study was to determine whether remote IP is also effective in other tissues such as muscle flaps. Twenty male Wistar rats were divided into three experimental groups. The rat cremaster flap in vivo microscopy model was used for assessment of ischemia/reperfusion injury. In the control group (CG, n = 8), a 2-hr flap ischemia was induced after preparation of the cremaster muscle. In the "classic" IP group (cIP, n = 6), a brief flap ischemia of 10 min was induced by preclamping the pedicle, followed by 30 min of reperfusion. A 10-min ischemia of the contralateral hindlimb was induced in the remote IP group (rIP, n = 6). The limb was then reperfused for 30 min. Flap ischemia and the further experiment were performed as in the CG. In vivo microscopy was performed after 1 hr of flap reperfusion in each animal. A significantly higher red blood cell velocity in the first-order arterioles and capillaries, a higher capillary flow, and a decreased number of leukocytes adhering to the endothelium of the postcapillary venules were observed in both preconditioned groups by comparison to the control group (P < 0.05). The differences within the preconditioned groups were not significant for these parameters. Our data show that ischemic preconditioning and improvement of flap microcirculation can be achieved not only by preclamping of the flap pedicle, but also by induction of an ischemia/reperfusion event in a body area distant from the flap prior to elevation. These findings indicate that remote IP is a systemic phenomenon, leading to an enhancement of flap survival. Our data suggest that remote IP could be performed simultaneously with flap elevation in the clinical setting without prolongation of the operation and without invasive means.

Acute remote ischemic preconditioning II: the role of nitric oxide.

The purpose of this study was to determine whether nitric oxide (NO) plays a role in the mechanism of acute "classic" as well as acute remote ischemic preconditioning (IP). Thirty-two male Wistar rats were divided into five experimental groups. The rat cremaster flap in vivo microscopy model was used for assessment of ischemia/reperfusion injury. In the control group (CG, n = 8), a 2-hr flap ischemia was induced after preparation of the cremaster muscle. The animals of group NO (n = 6) received 500 nmol/kg of the NO-donor spermine/nitric oxide complex (Sper/NO) intravenously 30 min prior to ischemia. The group LN + P (L-NAME + preclamping, n = 6) received 10 mg/kg Nomega-nitro-L-arginine methyl ester (L-NAME) intravenously before preclamping of the flap pedicle (10-min cycle length, 30-min reperfusion). L-NAME (10 mg/kg) was administered in group LN + T (L-NAME + tourniquet, n = 6) before ischemia of the right hindlimb was induced, using a tourniquet for 10 min after flap elevation. The limb was then reperfused for 30 min. Thereafter, flap ischemia was induced in each group as in group CG. In vivo microscopy was performed after 1 hr of flap reperfusion in each animal. Group NO demonstrated a significantly higher red blood cell velocity (RBV) in the first-order arterioles and capillaries, a higher capillary flow, and a decreased number of leukocytes adhering to the endothelium (stickers) of the postcapillary venules by comparison to all other groups (P < 0.05). The average capillary RBV and capillary flow were still higher in the CG than in the groups receiving L-NAME (P < 0.05). The data show that NO plays an important role in the mechanism of both acute "classic" as well as acute remote IP, since the administration of a NO-donor previous to ischemia simulates the effect of IP, whereas the nonspecific blocking of NO synthesis by L-NAME abolishes the protective effect of flap preconditioning.

Ischemic preconditioning by brief extremity ischemia before flap ischemia in a rat model.

Ischemic preconditioning is a protective endogenous mechanism to reduce ischemia/reperfusion injury and is defined as a brief period of ischemia the authors term "preclamping." This is followed by tissue reperfusion and is believed to increase the ischemic tolerance. The objective of this study was to determine whether acute remote ischemic preconditioning, which has been reported to be successful for other organs, such as the heart, kidney, intestine, and liver, will also result in an enhancement of survival in flaps, and whether remote ischemic preconditioning is as effective as preclamping. Forty male Wistar rats were divided into four experimental groups. An extended epigastric adipocutaneous flap (6 x 10 cm) was raised, based on the left superficial epigastric artery and vein. In the control group, a 3-hour flap ischemia was induced. In the preclamping group, a brief ischemia of 10 minutes was induced by clamping the flap pedicle, followed by 30 minutes of reperfusion. Ischemia of the right hind limb was induced in the femoral ischemia group by clamping the femoral artery and vein for 10 minutes after flap elevation. The limb was then reperfused for 30 minutes. Thereafter, flap ischemia was induced as in the control group. A similar protocol was used in the tourniquet group. A tourniquet was used to induce hind-limb ischemia. The experiment was then performed as in the femoral ischemia group. Mean flap necrosis area was assessed for all groups on the fifth postoperative day using planimetry software. Average flap necrosis area was 68.2 +/- 18.1 percent in the control group, 11 +/- 8.38 percent in the preclamping group, 12.5 +/- 5.83 percent in the femoral ischemia group, and 24 +/- 11.75 percent in the tourniquet group. All preconditioned animals demonstrated a significantly lower area of flap necrosis than the control group (p < 0.001, one-way analysis of variance, post hoc Tukey's test). The data show that ischemic preconditioning and enhancement of flap survival can be achieved not only by preclamping of the flap pedicle but also by induction of an ischemia/reperfusion event in a body area distant from the flap before harvest. These findings indicate that remote ischemic preconditioning is a systemic phenomenon, leading to an enhancement of flap survival. The exact mechanism is not yet completely understood. The data suggest that remote ischemic preconditioning could be performed simultaneously with flap harvest in the clinical setting, resulting in an improved flap survival without prolongation of the operation. This may decrease the rate of partial flap loss or fat necrosis, especially in high-risk groups such as smokers, those with irradiated tissues, and obese patients.

Transcardiopulmonary vs pulmonary arterial thermodilution methods for hemodynamic monitoring of burned patients.

The objective of this study was to validate a new method of transcardiopulmonary thermodilution for assessment of cardiac index (CI), stroke volume index (SVI), systemic vascular resistance index (SVRI) and additional parameters such as intrathoracic blood volume index and extravascular lung water index (EVLWI) by comparison with conventional pulmonary artery catheter values in a severely burned population. The pulmonary artery measurements were performed continuously with the Vigilance system, and the transcardiopulmonary thermodilution with the PiCCO(R) system. One hundred thirteen measurements with each system on up to six consecutive days were taken in 14 severely burned patients (average TBSA, 49.6%; average ABSI, 10.3), aged 21 to 61 years (mean, 42.2 years) and compared intraindividually. An excellent correlation between the two methods was shown for CI (r = 0.80) and its derived parameters SVI and SVRI in states of low to normal cardiac output. The correlation was poor for cardiac indices greater then 5.5 up to their maximum values (r = 0.46). No correlation between index of oxygenation (PaO2/FiO2) vs EVLW I was observed. There was no difference between survivors and nonsurvivors, and between patients with and without inhalation injury in EVLWI. The method of transcardiopulmonary thermodilution is suitable to assess SVI, CI and SVRI under the special pathophysiologic condition of a major burn for low to normal cardiac output states. It is less reliable when cardiac output is high. The lower cost and less invasive nature are the advantages of the system compared with use of the pulmonary artery catheter. The role of intrathoracic blood volume index and EVLWI in cardiopulmonary monitoring of severely burned patients remains to be further determined.