Harald Andel

Magnesium sulfate reduces intra- and postoperative analgesic requirements

In a randomized, double-blind study with two parallel groups, we assessed the analgesic effect of perioperative magnesium sulfate administration in 46 ASA physical status I or II patients undergoing arthroscopic knee surgery with total IV anesthesia. The patients received either magnesium sulfate 50 mg/kg preoperatively and 8 mg [center dot] kg-1 [center dot] h-1 intraoperatively or the same volume of isotonic sodium chloride solution IV. Anesthesia was performed with propofol (2 mg/kg for induction, 6-8 mg [center dot] kg- 1 [center dot] h- 1 for maintenance), fentanyl (3 [micro sign]g/kg for induction), and vecuronium (0.1 mg/kg for intubation). Intraoperative pain was defined as an increase of mean arterial blood pressure and heart rate of more than 20% from baseline values after the induction of anesthesia and was treated with bolus fentanyl (1-2 [micro sign]g/kg). Postoperative analgesia was achieved with fentanyl (0.5 [micro sign]g/kg) and evaluated using the pain visual analog scale for 4 h. During the intraoperative and postoperative periods, patients in the magnesium group required significantly less fentanyl than those in the control group (control group 0.089 +/- 0.02 [micro sign]g [center dot] kg-1 [center dot] min-1 versus magnesium group 0.058 +/- 0.01 [micro sign]g [center dot] kg-1 [center dot] min- 1; P < 0.05 and control group 0.021 +/- 0.013 [micro sign]g [center dot] kg-1 [center dot] min-1 and magnesium group 0.0031 +/- 0.0018 [micro sign]g [center dot] kg-1 [center dot] min-1; P < 0.01 for intraoperative and postoperative periods, respectively). We conclude that, in a clinical setting with almost identical levels of surgical stimulation, IV magnesium sulfate administration reduces intraoperative and postoperative analgesic requirements compared with isotonic sodium chloride solution administration. Implications: The perioperative administration of IV magnesium sulfate reduces intra- and postoperative analgesic requirements in patients with almost identical levels of surgical stimulus. Our results demonstrate that magnesium can be an adjuvant to perioperative analgesic management. (Anesth Analg 1998;87:206-10)

Indocyanine green video angiographies help to identify burns requiring operation

The key decision in the treatment of thermal injuries is the determination of the depth of the burn wound and the resultant decision on treatment options. The trend in the treatment of deep dermal and full thickness burns is toward very early excision and grafting to reduce the risk of infection, decrease scar formation, shorten hospital stay, and thereby reducing costs. Traditionally, this has involved serial clinical examinations, which involves primarily subjective judgment. Various objective examination techniques, supplementing the clinical diagnosis, have been suggested, but none has yet achieved widespread clinical acceptance. It has frequently been postulated that the blood flow in injured tissue indicates the extent of tissue damage. In this study, the clinical and scientific impact of indocyanine green (ICG) video angiography was tested in 20 patients. A wide range of depth of injury and etiology was included and analyzed. In all cases considered, video angiography was possible. The measurements and observations correlated well with the actual burn depth, which was assessed clinically (pre- and intraoperative assessment) and histologically (biopsies). In conclusion, ICG video angiography seems to be a practical method to describe vascular patency in a burn wound. The results indicate that ICG fluorescence angiography is a practical, accurate, and effective adjunct to clinical methods for estimating burn wound depth and thereby to assist in the rational assessment of treatment options. Furthermore, it allows an objective, qualitative and quantitative observation of the dynamic changes in burn wound depth, which are observed during the acute post-burn period, thereby indicating optimal timing of the first operation.

Progression of burn wound depth by systemical application of a vasoconstrictor: an experimental study with a new rabbit model

The final depth of a necrosis resulting from burn trauma is determined within 3 days. The zone of stasis has the potential for complete regeneration or there may be ischemic influences that lead to necrosis. In our model, we examined the dermal influence of vasoconstrictors with reference to the development of burn necrosis. On the backs of New Zealand white rabbits (4.0-4.5 kg) standardized lesions were made with a heated aluminum stamp at 80 degrees C, 14 s in duration. The lesions were intradermal, whereby the border zone of the coagulated tissue was found in the middle two quarters of the dermis in 100% of untreated animals after 72 h. For dermal vasoconstriction epinephrine in a dose of 0.5 microg/kg/min was used. There were two groups of seven animals each. One group received epinephrine and the dosage was dependent on the clinical state of the animal. Several cycles were administered within a 3-day period. The reduction of skin perfusion was documented by Laser-Doppler-flowmetry. After 3 days, the skin with the lesions was excised and using a hematoxylin dye, a histological examination followed. The parameter used to determine the efficacy was the thickness of the uncoagulated part of the excised dermis. Over a period of 48 h, an average of 2.3 epinephrine cycles of average of 88 min per animal in duration resulted in an average reduction of skin diffusion of 41%. The uncoagulated part of the dermis in the epinephrine group was 28.6% average; in the control group, this was 43.5%. The statistical analysis revealed significant differences with a p-value of 0.0312 (significant, when value is less than 0.05). The test results indicate that temporary reduction of skin perfusion through external administration of vasocontrictors may lead to progression of burn necrosis in our animal model. Clinically, this result indicates that for patients with burn injuries and systemic inflammatory response syndrome who have insufficient volume therapy, the administration of vasocontrictors may produce similar results in the injured area.

Burn treatment in the elderly

The population of elderly patients is expected to rise continuously over the next decades due to global demographic changes. The elderly seem to be most vulnerable to burns and their management remains undoubtedly a challenge. A clear age margin for elderly patients is not yet defined, but most studies adhere to the inclusion of patients 65 years and above, but the general condition and social situation must be taken into account. The understanding of the physiological basis of aging and its related pathophysiological changes has only marginally influenced treatment and decision making in elderly burn patients. When looking at treatment regimens currently applied in elderly burn patients, the discussion of standards in intensive care as well as surgical strategies is ongoing. However, trends towards a moderate, non-aggressive resuscitation approach and careful inclusion of key parameters like physiological age, pre-burn functional status and premorbid conditions, seem to be useful guidelines for interdisciplinary treatment decisions. Once ordered for surgical treatment, the amount of body surface area operated in one session should be adapted to the general status of the patient. Even if older burn victims have a reported higher mortality rate than younger patients, improved therapeutic options have contributed to a reduced mortality rate even in the elderly over the last decades. As a result of improved outcome, more attention has to be given to a comprehensive rehabilitation program. This review will give an overview of the current literature and will draw attention to specific topics related to this important subpopulation of burn patients.

Nutrition and anabolic agents in burned patients

PURPOSE OF REVIEW Much of the morbidity and mortality of severely burned patients is connected with hypermetabolism and catabolism with its accompanying impairment of wound healing and increased infection risks. In order to prevent the erosion of body mass, nutritional support and other strategies to prevent catabolism have become a major focus in the care of severely burned patients. RECENT FINDINGS Major themes discussed in recent literature are dealing with enteral versus parenteral nutrition and gastric versus duodenal feeding. The possibility of overfeeding is another important aspect of high calorie nutrition as commonly used in burned patients. Specific formulas for enteral nutrition for specific metabolic abnormalities are under evaluation as well as the role of anabolic and anticatabolic agents. SUMMARY From the clinical literature, total enteral nutrition starting as early as possible without any supplemental parenteral nutrition is the preferred feeding method for burned patients. Using a duodenal approach, especially in the early postburn phase, seems to be superior to gastric feeding. Administration of high calorie total enteral nutrition in any later septic phase should be critically reviewed due to possible impairment of splanchnic oxygen balance. Therefore, measurement of CO(2)-gap should be considered as a monitoring method during small bowel nutrition. The impact on the course of disease of supplements such as arginine, glutamine and vitamins as well as the impact of the use of anabolic and anticatabolic agents is not yet evident. Furthermore, the effect of insulin administration and low blood sugar regimes on wound healing and outcome in burned patients should be evaluated in future studies.

Propofol without muscle relaxants for conventional or fiberoptic nasotracheal intubation: a dose-finding study.

UNLABELLED Endotracheal intubation has been performed during the administration of propofol anesthesia without neuromuscular blockade. In this study, we determined the propofol dose required for conventional nasotracheal or for fiberoptic nasotracheal intubation of all patients. Thirty-two patients undergoing maxillofacial surgery were randomly assigned to the conventional (n = 16) or to the fiberoptic (n = 16) intubation group. In both groups, anesthesia was induced by using IV fentanyl and IV titrated propofol according to clinical need (spontaneous respiration rate, verbal response). An endotracheal tube was placed nasally in the pharynx and the vocal cords visualized by using a fiberscope inserted via the tube. In the conventional group, the larynx was visualized additionally with a laryngoscope blade (Miller). In both groups propofol was titrated until the vocal cords opened. Patients were tracheally intubated, and the propofol dose was recorded. In all patients, the trachea could be intubated without the use of muscle relaxants. Considerable interindividual differences of dose requirements were observed. The amount of propofol required in the conventional group was significantly (P < 0.0001) larger (median +/- SD: 2.74 +/- 1.59 mg/kg; range 1.95-7.07 mg/kg) than in the fiberoptic group (1.37 +/- 0.59 mg/kg; 0.72-2.86 mg/kg). Hemodynamics remained stable in all patients. Postintubational hoarseness occurred in three patients of each group. Fiberoptic nasal intubation without a muscle relaxant can be facilitated with significantly smaller and more predictable dosages of propofol than conventional nasal endotracheal intubation. The possibility of titrating the propofol dose under assisted ventilation until the vocal cords open during fiberoptic nasotracheal intubation and the better predictability of the required dose favors the fiberoptic approach. IMPLICATIONS In this study, contrary to all preceding studies using predefined doses of propofol and opioids, we determined the minimal required propofol dose in combination with fentanyl for conventional or fiberoptic nasotracheal intubation without muscle relaxants.

Impact of early high caloric duodenal feeding on the oxygen balance of the splanchnic region after severe burn injury

Early enteral nutrition is recommended in burned patients. Depending on the amount administered, enteral feeding causes an increase of intestinal oxygen-demand. Although early moderate enteral nutrition has been shown to be beneficial, early high calorie enteral nutrition might lead to an imbalance of the O(2)-balance of the gut since intestinal perfusion is decreased after major burns. In 20 severely burned patients during the first 48 h of early high caloric duodenal feeding an assessment of the CO(2)-gap between the arterial and the gastric CO(2), as parameter for the intestinal O(2)-balance, was performed. Time points were prior to starting the enteral nutrition (BASE) subsequently every 30 min after increasing the amount of nutrition administered and from the 11th to the 48th h after beginning of nutrition in intervals of 6 h. In none of the patients was the CO(2)-gap increased during the rapid increase of enteral nutrition. On the contrary the CO(2)-gap decreased significantly. We conclude that high caloric duodenal feeding in the early hypodynamic postburn phase does not have adverse effects on the oxygen balance of the intestine.

Serum cholesterol and triglycerides: potential role in mortality prediction

The present study was performed in order to evaluate the diagnostic usefulness of serial cholesterol and triglycerides measurements in patients with severe burns. One of the main objective was to find out if these parameters are clinically relevant to determine the morbidity of a burn patient and thereby the patients outcome. In 220 patients with thermal injuries, cholesterol and triglyceride concentrations were measured daily. Blood samples were drawn immediately upon admission and thereafter daily until patients discharge or death. For both parameters, a characteristic course was noted: in the group of non-survivors, a decrease of cholesterol prior to death was noted, while survivors, increased prior to discharge. The time courses of both groups (survivors-non-survivors) differed statistically significantly (P=0.0068). An increase in triglycerides was observed in all non-survivors prior to death, but in the group of survivors triglycerides remained more or less unchanged. These time courses also had statistically significant differences (P=0.0004). In our 220 patients, changes in cholesterol (P<0.0001, hazard ratio 1.02) and triglycerides (P=0.0008, hazard ratio 1.01) had comparable capability to predict the severity of a burn trauma and thereby its outcome than the established parameters in the treatment of burns (total body surface area burned, age, inhalation). We consider the serial measurements of cholesterol and triglycerides as clinically relevant to assess the morbidity of a patient and thereby to estimate the patients outcome. We think that these serial measurements provide useful information for the clinician treating patients with severe burns.

Hydrocortisone improved haemodynamics and fluid requirement in surviving but not non-surviving of severely burned patients

Recent studies have shown that administration of hydrocortisone may lead to a reduction of catecholamines and to an improved outcome in septic patients. However, there are no data on the use of hydrocortisone in burn patients although in these patients reduction of vasopressors might be even more crucial for outcome due to improvement of skin perfusion. This study presents the first results on the impact of hydrocortisone administration in norepinephrine dependent severely burned patients. In a prospective cohort study fourteen consecutive severely burned patients received, 12h after norepinephrine dependency, a hydrocortisone bolus of 100mg followed by 0.18mg/(kgh) hydrocortisone. The course of the necessary norepinephrine dose, as well as the fluid balance was documented 12h prior and after the first dosage of hydrocortisone. Statistical analysis showed an unexpected increase of the required norepinephrine dosage. A statistical post hoc evaluation of surviving and non-surviving patients revealed a significant increase of norepinephrine in non-survivors whereas in survivors it was possible to reduce norepinephrine significantly. Furthermore, the median fluid requirement of surviving patients could be significantly reduced whereas in the group of non-survivors there was no change of volume needed. Our data suggests that hydrocortisone might be useful in selected patients with severe burn injuries. However, patients not responding to hydrocortisone administrations seem to have a poor prognosis. Our findings are in contrast to previously published data on septic patients, in whom hydrocortisone administration resulted in a reduction of norepinephrine. In burned patients the severity of trauma seems to have more profound influence on the pathophysiological mechanism of sepsis. Due to the high number of non-responders, the potential immune suppression and impaired wound healing caused by the side effects of hydrocortisone, further selection criteria seem to be necessary. A short ACTH-test might be considered prior to hydrocortisone administration to select patients who might benefit from this therapy. In summary, further prospective controlled studies will be necessary to establish hydrocortisone in the routine therapy of severely burned patients.

The axillary vein central venous catheter in severely burned patients

In severely burned patients the approach to the central vein is often difficult due to concomitant edema, but also due to the fact that the skin area, where commonly used approaches are performed, is burned as well, whereas the axillary region is often not involved. In order to perform an axillary approach to the central vein as an alternative to the commonly used approaches in patients, an anatomical dissection in fresh human cadavers was carried out. Considering the anatomical landmarks which were found during dissection of the axillary region, the axillary approach to the central vein was used in 35 patients in our intensive burn care unit with unaffected axillary skin. In three cases the only complication observed was an occasional puncture of the axillary artery without major hematoma. The infection rate of the catheters was similar to the commonly used puncture sites. This approach to the central venous line in severely burned patients can be recommended.