Charlotte Holm

Perfusion zones of the DIEP flap revisited: a clinical study.

Background: The Hartrampf perfusion zones of the lower abdominal flap are generally accepted. They were empirically based on the clinical impression of the perfusion in the first 16 unipedicled transverse rectus abdominis musculocutaneous flaps and have been uncritically adopted for the free transverse rectus abdominis musculocutaneous and the free deep inferior epigastric perforator (DIEP) flap. Scientific data proving the validity of these perfusion zones do not exist. The objective of this study was to evaluate and quantitatively assess the perfusion zones of the DIEP flap. Methods: In a clinical, prospective study of 15 patients undergoing DIEP flap breast reconstruction, tissue perfusion was intraoperatively assessed using the method of laser-induced fluorescence of indocyanine green. Results: Perfusion of zones I, II, and III was seen 25, 41, and 32 seconds, respectively, after injection, and the perfusion index constituted 76, 25, and 47 percent (median) of normal tissue. Perfusion of zone IV was completely absent in five patients (33 percent); in the remaining patients, it was dramatically decreased (5 percent) and occurred with a delay of 67 seconds. Conclusions: On the basis of the results of this study, the Hartrampf concept of a centrally perfused skin ellipse with declining perfusion of its peripheral ends is wrong and should be revised. Instead, one should think of the lower abdominal flap as two halves separated by the midline. The ipsilateral half has an axial pattern of perfusion; the contralateral half shows a random-pattern, individually variable blood supply. Therefore, the classic Hartrampf zones should be rearranged, switching zones II and III.

Acute renal failure in severely burned patients

Acute renal failure (ARF) is a well known complication of severe burns and is an important factor leading to an increase in mortality. In order to analyze possible pathogenetic and prognostic factors associated with ARF in burned patients we reviewed in a retrospective study the files of 328 patients with burns > 10% body surface area (BSA), admitted to our burn unit between 01.01.94 and 01.05.98. We found 48 patients with acute renal failure corresponding with an incidence of 14.6%. Patients with ARF had a mean burned surface area of 48% (13-95) and an abbreviated burn severity index score (ABSI) of 9.8 (4-15). Thirty eight (79%) of these patients had an inhalation injury diagnosed. Renal insufficiency was divided in a late and an early form depending on its time of onset and we found 15 (31%) patients with ARF occurring within the first 5 days of the hospital stay and 33 (69%) patients with ARF developing >5 days following the thermal injury. The incidence of myoglobinuria and hypotension during the resuscitation phase was significantly higher in the group with early ARF, whereas patients with late ARF presented sepsis more frequently than patients with early occurring renal failure. Accordingly, potential nephrotoxic antibiotics were administered more often in patients with late ARF. Patients with ARF were treated by continuous arteriovenous hemofiltration (CAVH) for a mean period of 10.5 days (1-47) and CAVH was associated with a complication rate of 10%. Most of the complications were associated with the vascular access in the femoral artery. The mortality rate in patients with ARF was 85% and death was due to multiple organ failure in 83% of the cases. Only burned BSA and inhalation injury proved to be significantly correlated with the development of ARF, whereas age, third degree burn or electric injury were not significantly different between the two groups. Neither age, TBSA, day of onset of ARF nor duration of the renal replacement therapy proved to be significantly different comparing survivors with non-survivors, and thus predictive for the survival rate.

Intrathoracic blood volume as an end point in resuscitation of the severely burned: an observational study of 24 patients.

BACKGROUND Treatment of burn shock according to empirical resuscitation formulas is still considered the gold standard, and the burn community does not advocate the use of invasive cardiorespiratory monitoring in general. As a consequence, data dealing with early postburn hemodynamics are sparse, and only few studies have paid attention to the topic of end-point burn shock resuscitation. However, recent studies have suggested that burn survival may be improved when invasive monitoring is used to guide fluid therapy during the shock phase. MATERIALS AND METHODS In an observational study of 24 patients with severe burns, the transpulmonary double indicator dilution technique was used for semi-invasive hemodynamic monitoring. The clinical utility of the intrathoracic blood volume (ITBV) as an end-point variable for fluid resuscitation was evaluated, comparing correlation of filling pressure obtained by a pulmonary artery catheter and intrathoracic blood volume to cardiac index and oxygen delivery. In addition fluid volume predicted by the Parkland burn formula was compared with the actual fluid volume given when ITBV was used as end point for resuscitation. RESULTS ITBV-guided resuscitation was associated with restoration of preload and peripheral delivery of oxygen within 24 hours in the majority of patients. Augmentation of ITBV was significantly correlated with changes in cardiac index and oxygen transport rate. No such correlation could be demonstrated for the conventional preload parameters such as central venous pressure and pulmonary capillary wedge pressure. Thus, ITBV seemed in burned, hypovolemic patients a better indicator of the preload component of the cardiac output than the conventional preload parameters obtained with the pulmonary artery catheter. Significantly larger volumes of crystalloids than predicted by the Parkland formula were administered when ITBV was used as end point for resuscitation. The extravascular lung water remained normal during this extraordinary high volume load. CONCLUSION ITBV may be a reliable preload indicator to guide volume therapy in life-threatening burns, and end-point-fixed resuscitation to this parameter seems to be associated with significantly higher fluid administration than calculated compared with traditional burn formulas. The effects of burn resuscitation to fixed end points on survival and multiple organ failure should be evaluated in future randomly assigned trials.

Haemodynamic and oxygen transport responses in survivors and non-survivors following thermal injury.

Resuscitation from shock based on invasive hemodynamic monitoring has been widely used in trauma and surgical patients, but has been only sparsely evaluated in thermally injured patients, probably due to fear of invasive monitoring in this group of patients. However, end-point resuscitation to fixed circulatory and oxygen transport values has been proposed to be associated with an improved survival rate following trauma and high-risk surgery. Furthermore, the early circulatory response to resuscitation has been shown to be predictive of survival in these patients. In this study the early hemodynamic and oxygen transport profile following thermal injury was analysed with the aim to detect possible differences in the response of survivors and non-survivors. The transpulmonary thermodilution technique was used for hemodynamic monitoring of 21 patients, who were admitted to our burn unit with severe burns. Six patients died and 15 patients survived to leave the intensive care unit. Survivors were found to have a significantly higher cardiac index and oxygen delivery rate during the early postburn period than non-survivors. Furthermore, initial serum lactate levels as well as the ability to clear elevated lactate were found to be significantly associated with survival. Blood pressure and heart rate were not significantly different between the two groups of patients. All patients received significantly higher volumes of crystalloids during the first 24 h than predicted from the Baxter formula, independent of outcome. We concluded that standard vital signs such as blood pressure and heart rate may be invalid as outcome related resuscitation goals, and too insensitive to ensure appropriate fluid replacement. The response to fluid therapy may be significantly associated with outcome; survivors responding with an augmentation of cardiac output and oxygen delivery not seen in non-survivors. Lactate levels seem to correlate with organ failure and death and appear a suitable end-point for resuscitation of severely burned patients.

Effects of aesthetic abdominoplasty on abdominal wall perfusion: a quantitative evaluation.

Abdominoplasty procedures involve a high risk of early complications, including hematomas, seromas, necrosis, and wound-healing problems. Their rationale is evident from the vascular anatomy of the abdominal wall, as traditional abdominoplasty includes a division of the main perforating vessels. No studies exist to quantitatively assess the consequences of abdominoplasty on the perfusion of the random pattern abdominal flap. To address this issue and quantify the influence of classic abdominoplasty on the perfusion of the abdominal skin, the authors performed a prospective clinical trial including 15 low-risk patients undergoing abdominoplasty for aesthetic purposes. Perfusion of the abdominal flap was measured intraoperatively using the technique of dynamic laser-fluorescence-videoangiography. In the region between the umbilicus and the transverse scar (zone 1), the increment of fluorescence (the slope of the intensity curve during inflow of the indocyanine green) was recorded and compared with the intensity curve of normal tissue that was not involved in surgery (thoracic wall). The results of the intraoperative indocyanine green perfusography showed a significant impairment of the vascular supply of zone 1 in all patients. The mean perfusion index in this region was 17.2 percent (range, 5 to 32 percent) of the perfusion of the surrounding skin that was not involved in surgery. The complication rate was 33 percent (five patients) and included two cases of hematoma and three cases of scar dehiscence with skin and/or fat necrosis. These data indicate that conventional abdominoplasty including extended undermining and division of the superficial and the deep arterial systems causes profound devascularization of the abdominal flap. This might explain the high incidence of complications following this procedure.

Arterial thermodilution: an alternative to pulmonary artery catheter for cardiac output assessment in burn patients

STUDY OBJECTIVE To study the agreement between cardiac output measurements with the pulmonary artery catheter and with the transpulmonary thermodilution technique in patients with burns. DESIGN Prospective, clinical study. PATIENTS 23 patients with serious burns and an abbreviated burn severity index score (ABSI)>6. SETTING intensive care unit for severely burned in a burn center in Germany. RESULTS A total number of 218 cardiac output measurements obtained during the first 72 h postburn were analysed. In the pulmonary artery group, mean cardiac index was 3.93 l/min/m2 and ranged from 0.96 to 9.58. In the transpulmonary group the cardiac index measurements ranged from 0.96 to 9.61 with a mean of 4.0 l/min/m2. During the entire observation period cardiac index was consistently higher in the transpulmonary group than in the pulmonary artery group with a bias of 0.32 l/min/m2 and a standard deviation (S.D.) of 0.29 l/min/m2. Linear regression analysis revealed CI(arterial)=0.98xCI(pulm)+0.22l/min/m2 (r=0.9678, P<0.038). Bias and precision to each time point according to Bland and Altman demonstrated a good agreement between both techniques. CONCLUSION The transpulmonary thermodilution offers an attractive, less invasive alternative to the pulmonary artery catheter in patients with burns. Arterial thermodilution for CO measurements is as precise as PA thermal dilution, and CO(pulm) can be replaced by CI(arterial) when basic methodological principles are respected.

Interindividual variability of the SIEA Angiosome: effects on operative strategies in breast reconstruction.

Background: The vascular territory of the superficial inferior epigastric artery (SIEA) remains to be clarified. The SIEA flap has traditionally been classified as a hemiabdominal flap, but recent evidence points to the fact that a sizable superficial artery is capable of supplying the entire abdominal ellipse. Methods: Twenty-five patients who met the anatomical criteria for undergoing SIEA flap surgery were studied. The abdominal flap was raised on a superficial inferior epigastric pedicle; the dominant musculocutaneous perforators were preserved and clamped above the abdominal fascia on either side. The vascular territory of the superficial epigastric artery and the contribution of the deep epigastric system were visualized using laser-induced fluorescence of indocyanine green. The surgical technique was modified (SIEA, deep inferior epigastric perforator, or bipedicle) based on perfusion measurements and the indication for surgery. Results: The SIEA vascular territory did not cross the midline in 16 patients (64 percent), and ranged from 0 percent (two patients) to the entire abdominal ellipse (five cases). Fourteen patients (56 percent) were operated on with a unipedicle SIEA flap, five patients (20 percent) were operated on with a bipedicle flap, and in six (24 percent), a conventional deep inferior epigastric perforator flap was used. As a SIEA flap was originally intended in all patients, intraoperative perfusion measurements changed the surgical plan in 11 patients (44 percent). Conclusions: The SIEA angiosome is variable and ranges from 0 to 100 percent of the lower abdominal flap. Intraoperative perfusion measurements are indispensable for evaluating the sufficiency of this pedicle for tissue transfer, especially if the contralateral flap zones are needed for reconstruction.

Assessment of the patency of microvascular anastomoses using microscope-integrated near-infrared angiography: a preliminary study.

Technical problems at the site of the anastomosis compromise an underappreciated proportion of microsurgical free tissue transfers. Intraoperative identification of technical errors may be able to prevent reexploration surgery and early flap failure. We report the first human study on a new microscope‐integrated fluorescence angiography technique, which allows for intraoperative imaging of the anastomotic site.

The ideal split-thickness skin graft donor-site dressing: a clinical comparative trial of a modified polyurethane dressing and aquacel.

Background: The almost single disadvantage of conventional polyurethane film dressings, uncontrolled leakage, is probably as often described as its numerous advantages for split-thickness skin graft donor sites. This shortcoming can be overcome by perforating the polyurethane dressing, which permits controlled leakage into a secondary absorbent dressing. The study was conducted to compare the polyurethane dressing system and Aquacel, a hydrofiber wound dressing, which also seems to fulfill all criteria of an ideal donor-site dressing. Methods: This prospective, randomized, double-blind clinical trial included 50 adult patients. Skin graft donor sites were divided equally for the application of Aquacel and polyurethane dressing. The dressings were kept unchanged for 10 days. After removal of the dressing at day 10, the epithelialization rate of both sites was evaluated. Pain scores were assessed according to a 0 to 5 numeric pain scale every postoperative day and during dressing removal. Results: On postoperative day 10, 86.4 percent of the polyurethane dressing donor sites showed complete reepithelialization compared with 54.5 percent of the Aquacel-treated donor sites (p < 0.001). Polyurethane dressing was significantly less painful until and during removal of the dressing (p < 0.001). There was no significant difference with respect to scar formation. Conclusions: Overall, polyurethane dressing was superior to Aquacel. Further attributes of the polyurethane dressing such as ease of application, low labor input, high patient comfort, and protection against secondary wound infection qualify this dressing system as an ideal wound covering for donor sites. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, II.

Sensitivity and Specificity of ICG Angiography in Free Flap Reexploration

Microscope-integrated indocyanine green near-infrared videoangiography (ICGA) is a new imaging technique to assess vascular flow through diminutive vessels used in microvascular surgery. The purpose of this investigation was to evaluate the diagnostic accuracy of ICGA in detecting microvascular thrombosis in reexploration surgery. Patients undergoing emergent reexploration surgery after free tissue transfer were enrolled in this clinical study. After the patients had been returned to the operating room the pedicle vessels were exposed and a microangiography was performed. Independent of the result, the anastomoses were opened and surgically explored. Sensitivity and specificity was calculated, using the result of exploration surgery as a reference standard. Of 200 free flaps 20 (10%) underwent reexploration surgery. The most common surgical finding was microvascular thrombosis (55%). In one case vascular compromise was due to confusion of artery and vein with anastomosis of two veins. In 40% of patients an intact vascular pedicle was found. The sensitivity and specificity of ICGA to detect microvascular thrombosis was 100% and 86%, respectively. ICGA provides an excellent diagnostic accuracy for detecting microvascular thrombosis in reexploration surgery. Routine implementation of this technique may expedite a correct diagnosis and facilitate the surgical approach by preventing unnecessary surgical manipulation of intact anastomoses.