Infusion of hot crystalloid during operative burn wound debridement

Reduced Intraoperative Blood Loss and Hypothermia in Burn Surgery using Cardiopulmonary Bypass Pumps

Objective: Patients presenting with total body surface area (TBSA) >40% burns require significant surgical treatment. Two substantial challenges during these surgeries are limiting blood loss and maintaining core temperatures. To overcome these challenges, several techniques have been developed, ranging from the Pitkin syringe method to the pneumatic tourniquet strategy for large-volume hyperthermic insufflation. Here, we compare the pneumatic tourniquet method to a roller pump method for maintenance of intraoperative normothermia and control of bleeding. Methods: We conducted a retrospective chart review of 20 patients presenting with TBSA >40% burns, 10 of whom were treated with the rapid infusion roller pump and 10 of whom were treated with the pneumatic tourniquet technique. Patients from each group were controlled for % TBSA, presence of inhalation injury, age, and date of admission. We reviewed transfusion requirement and the intraoperative temperatures, as well as the average intraoperative drop in temperature. Results: We observed improvement in the infusion volume, operative time, intraoperative temperature drop, minimum intraoperative temperature, estimated blood loss, and amount of required transfusion. Conclusions: Our study suggests that the rapid infusion roller pump technique is capable of achieving superior intraoperative bleeding control and temperature maintenance compared to the pneumatic tourniquet technique, resulting in decreased transfusion requirement.

Perioperative hypothermia: Causes, consequences and treatment

Perioperative hypothermia, core temperature below 36.0 °C, transpires due to disruption of thermoregulation by anesthesia coupled with cold exposure to procedural surroundings and cleansing agents. Although most publications have focused on thermoregulation disruption with general anesthesia, neuraxial anesthesia may also cause significant hypothermia. The clinical consequences of perioperative hypothermia are multiple and include patient discomfort, shivering, platelet dysfunction, coagulopathy, and increased vasoconstriction associated with a higher risk of wound infection. Furthermore, postoperative cardiac events occur at a higher rate; although it is unclear whether this is due to increased oxygen consumption or norepinephrine levels. Hypothermia may also affect pharmacokinetics and prolong postoperative recovery times and hospital length of stay. In order to combat perioperative hypothermia, many prevention strategies have been examined. Active and passive cutaneous warming are likely the most common and aim to both warm and prevent heat loss; many consider active warming a standard of care for surgeries over one hour. Intravenous nutrients have also been examined to boost metabolic heat production. Additionally, pharmacologic agents that induce vasoconstriction have been studied with the goal of minimizing heat loss. Despite these multiple strategies for prevention and treatment, hypothermia continues to be a problem and a common consequence of the perioperative period. This literature review presents the most recent evidence on the disruption of temperature regulation by anesthesia and perioperative environment, the consequences of hypothermia, and the methods for hypothermia prevention and treatment.

Early coagulopathy of major burns

INTRODUCTION AND AIMS

The pathophysiology and time-course of coagulopathy post major burns are inadequately understood. The aims of this study were to review the incidence of acute coagulopathy post major burns, potential contributing factors associated with this coagulopathy and outcome of patients who developed early coagulopathy.

METHODS

A retrospective review of all patients with major burns (≥20% total body surface area (TBSA)) presenting to a tertiary burns referral centre was conducted. Data on demographic, injury characteristics and fluid resuscitation practices were recorded and tested for association with coagulopathy (INR>1.5 or aPTT>60 s) at hospital presentation and within 24 h of burns injury. Mortality, intensive care unit (ICU) admission, mechanical ventilation and blood and blood product usage were primary endpoints.

RESULTS

There were 99 patients who met the inclusion criteria with 36 (16) %TBSA burns. Coagulopathy was present in only three patients on presentation, but 37 (37%) patients developed early onset (within 24 h of injury) coagulopathy. Early onset coagulopathy was independently associated with %TBSA burnt (p<0.001) and volume of fluid administered (p=0.005). Early onset coagulopathy was associated with higher volumes of blood and blood product administration, ICU admission and prolonged mechanical ventilation.

CONCLUSIONS

Post major burns, a very low proportion of patients presented with coagulopathy, but a substantial proportion of patients developed coagulopathy within 24 h. This and the association of coagulopathy with the volume of fluid resuscitation suggest dilution as a major cause of the early coagulopathy of major burns.

Steady-state and time-dependent thermodynamic modeling of the effect of intravenous infusion of warm and cold fluids

BACKGROUND

Hypothermia results in vital sign lability, coagulopathy, wound infections, and other sequelae. Normothermia can be restored by several modalities, including passive blanket heating, warm forced-air devices, and active fluid warming (AFW). In AFW, intravenously administered fluids are heated to 40 to 45 °C to minimize net thermal losses and to raise body temperature. Clinical studies have demonstrated the efficacy of AFW as part of a strategy encompassing several methods, but the isolated contribution of AFW to warming has not been theoretically examined in detail.

METHODS

A calorimetric model is derived to determine the functional dependence of warming on patient weight, hypothermia severity, infusion temperature, and volume infused. A second heat transfer model is derived to describe the time-dependent temperature changes of the periphery and core after warmed-fluid infusion.

RESULTS

There is an inverse linear relationship between the patient's initial temperature and the amount of warming achieved with a given volume. In contrast, as the temperature of the infusion approaches the desired final temperature, the volume required for a fixed temperature change increases nonlinearly. For weight-based boluses, the temperature change scales appropriately with patient mass. Infusion of 2 L of room-temperature crystalloid results in a decrease in body temperature of approximately one-third degree Celsius in the average normothermic adult. For the heat transfer model, previously reported rates of temperature drop and recovery after the intravenous infusion of cold fluids are qualitatively reproduced with a blood mixing time of approximately 15 minutes.

CONCLUSION

Our calculations reveal that AFW has a larger measurable beneficial effect for patients with more severe hypothermia, but true rewarming of the patient with AFW alone would require prohibitively large fluid volumes (more than 10 L of 40 °C fluid) or dangerously hot fluid (20 mL/kg of 80 °C fluid for a 1 °C increase). The major beneficial effect of AFW is the prevention of further net heat loss.

Avoiding hypothermia in the trauma patient

Hypothermia may be encountered during the management of severely injured patients, and with exception of deliberate hypothermia for neuroprotection, has been associated with increased morbidity and mortality. This review examines the recent literature with regard to risk factors for developing hypothermia, significance of hypothermia, therapeutic use of hypothermia, and invasive and noninvasive methods to prevent and treat hypothermia.

Massive transfusion of reconstituted whole blood is well tolerated in pediatric burn surgery

BACKGROUND

Massive transfusions can produce cardiovascular instability, metabolic abnormalities, dilutional coagulopathy, and pulmonary dysfunction. They also have been related to a higher incidence of infections. The purpose of this study was to assess the safety of massive transfusion of reconstituted whole blood.

METHODS

Twenty consecutive severely burned pediatric patients underwent near-total burn excision on admission and blood transfusion with reconstituted whole blood. Patients were studied for coagulopathies and postoperative complications related to massive transfusion.

RESULTS

Only one patient presented with postoperative bleeding related to acute renal failure. No other complications occurred. There were no septic episodes or pulmonary dysfunction. The amount of massive blood transfusion did not correlate with any laboratory or clinical disturbance.

CONCLUSION

Massive transfusion of reconstituted whole blood in severely burned pediatric patients is safe; it does not compromise hemostasis nor is it associated with an increased rate of septic episodes or pulmonary complications. A prospective randomized clinical trial comparing its effectiveness versus packed red cells is necessary.