How does burns cause metabolic acidosis

The concentration of albumin that binds to mostly acidic and neutral drugs is decreased in burn injury. AAG is also an acute-phase reactant, and its concentration increases twofold or greater in burn-injured patients, which decreases the free fraction of drugs bound by AAG. Hepatic clearance of drugs highly extracted by the liver depends primarily on hepatic blood flow and is relatively insensitive to alterations in protein binding.

Clearance of these drugs may decrease during the early postburn phase as a result of decreased liver and renal blood flow. Later on clearance of these drugs may increase during the hyperdynamic phase when hepatic blood flow increases e. Thus, renal clearance of some drugs increases. Phase II reactions involve conjugation, glucuronidation, and sulfation and seem to be relatively unaffected e.

Muscle relaxant pharmacology is significantly and consistently altered after burn injury. The current recommendation is to avoid succinylcholine administration in patients 48 h after burn injury. Martyn and Richtsfeld 62 have reviewed the topic of succinylcholine-induced hyperkalemia. Almost paralleling the hyperkalemia to succinylcholine, there is concomitantly a decreased sensitivity to the neuromuscular effects of nondepolarizing muscle relaxants NDMRs.

Because succinylcholine is contraindicated, treatment of laryngospasm in burned patients can include high-dose NDMRs, positive pressure ventilation, or deepening the anesthetic by intravenous and inhalational routes, if possible. Approximately 3 to 7 days after burn injury, the dose of NDMRs required to achieve effective paralysis can be substantially increased. An increased rocuronium dose of 1. This suggests that the major component to resistance to NDMRs is pharmacodynamic in nature.

Dose—response curves and time to maximal effect of rocuronium in adult burned and nonburned patients. In normal patients, dose of 0. Increasing doses of rocuronium shifted dose—response curves to the left. However, even with 1.

Train-of-four ratio refers to the ratio between fourth and first twitch tensions recorded in muscle during 2 Hz nerve stimulation. The choice of volatile anesthetic does not appear to influence outcome in burned patients.

Propofol clearance and volume of distribution are increased in patients with major burns during the hyperdynamic phase of burn injury. Opioid requirements are increased in burn-injured patients. Opioid tolerance makes pain management challenging throughout all phases of burn care. It is not uncommon for burn-injured patients to manifest opioid tolerance requiring dosing that far exceeds standard textbook recommendations fig.

If patients come to the operating room with infusions of sedatives and narcotics, these infusions should be continued and not stopped; the infusions have been maintained to reach a steady state of effect. Intraoperative analgesia can be achieved by increasing these infusions or turning to other drugs. Table 5 indicates some of the first-, second-, and third-line sedative and analgesic regimens used in our institutions during the acute hypermetabolic phase of burn injury.

In addition to pharmacokinetic changes documented for morphine, fentanyl, and propofol, animal studies of burn injury document changes in the spinal cord receptors.

Burn injury—induced tolerance to narcotics and sedatives. During procedures e. More recently, when the doses of morphine and midazolam exceed 0. Ketamine has many potential advantages for induction and maintenance of anesthesia in burn patients and is used by some centers as the primary anesthetic. Ketamine in normal patients is associated with hemodynamic stability, preserving airway patency as well as hypoxic and hypercapnic responses, and decreasing airway resistance.

Because of the increased secretions associated with ketamine, glycopyrrolate is frequently coadministered. Ketamine is now part of the pharmacologic armamentarium to treat burn- and opioid-induced tolerance to narcotics.

Bolus doses of ketamine can cause hypotension in patients with burn injury, despite ketamine-induced catecholamine release. Some studies have shown potential benefit of regional anesthesia in patients with burn injury by providing intraoperative anesthesia, improving postoperative analgesia and facilitating rehabilitation.

Patients often have more intense postoperative pain from the split-thickness skin donor site than from the grafted burn wound. Regional anesthesia in its simplest form may be tumescent local anesthesia injected into a donor site before harvesting 75 or it can take the form of subcutaneous catheter infusions, 76 peripheral nerve, or central neuraxial blocks.

Central neuraxial techniques spinals, epidurals have been used with good effect as both primary anesthetics and postoperative adjuncts in burn-injured patients. There are no reports suggesting that epidural abscesses are more common in burn patients, but reports have suggested that intravascular catheters are more likely to become infected if placed in or near burned tissue 78 ; similarly, caution is likely reasonable in selecting appropriate burn patients for central neuraxial techniques.

Truncal blocks paravertebral and transversus abdominis plane have been very useful to provide analgesia for donor site harvesting, and both block techniques are also amenable to placement of catheters to extend duration of postoperative analgesia.

The lateral femoral cutaneous nerve block is particularly well suited to block because it is exclusively a sensory nerve and innervates an area the lateral thigh that is frequently chosen for split-thickness skin grafts. Sometimes there is a need to cover the anterior and medial thigh due to the extent of skin harvest, and therefore, a fascia iliaca block can also be performed.

The hypermetabolic response after burn injury is more severe and sustained than any other form of trauma. Periods of 8-hour fasting before surgery make it difficult to meet the high caloric requirements of patients with major burn injury and may be poorly tolerated.

The feasibility and safety of continuing enteral feeding throughout operative procedures has been studied. Enteral feeding during surgery beyond the pylorus has been successful, provided the airway was secured via a cuffed ETT or tracheostomy to prevent aspiration of gastric contents.

It is difficult to estimate blood loss during burn excision because shed blood cannot be efficiently collected in a suction canister, surgical sponges may also contain irrigation fluid, blood can be concealed beneath the patient, and substantial bleeding can continue unobserved beneath bulky dressings.

Vigilant attention to several physiological variables is necessary to effectively maintain intravascular volume during burn excision. Published estimates of the amount of blood loss during burn excision operations are in the range of 2. If the patient is receiving parenteral nutrition, it is important that its infusion not be stopped because of the danger of hypoglycemia. After the initial massive fluid resuscitation for major burns, much effort is made restricting fluids and administering diuretics to hasten elimination of this edema.

In the perioperative period, it is important to avoid giving more fluid than is necessary. The use of colloids can help limit the amount of fluid needed to maintain preload.

The surgeons may inject large amounts of subcutaneous fluid to facilitate wound debridement and donor harvest. This fluid should also be limited.

As with the initial resuscitation, there is no single physiological endpoint to rely on for titrating fluid replacement. Constant vigilance and attention to all available information hemodynamic, metabolic, and urine output are necessary. The point at which red cell transfusion is beneficial varies greatly between patients.

Rather than focusing on hemoglobin or hematocrit, it is best to strive to maintain adequate preload and follow metabolic status. Blood component therapy should be reserved for patients with a demonstrated physiologic need, but anticipation of continued blood loss may indicate transfusion to prevent significant anemia rather than waiting to treat it when it occurs. In the past, administration of fresh-frozen plasma was guided by American Society of Anesthesiologists Task Force on Perioperative Blood Transfusion and Adjuvant Therapies recommendations that fresh-frozen plasma only be given when microvascular bleeding is present and coagulation factor deficiency is demonstrated.

Recent experience with civilian and military trauma has demonstrated that mortality is decreased by previous and more aggressive administration of fresh-frozen plasma with massive bleeding. It is not unusual for patients with large burns to meet these criteria during burn wound excision.

The clinical experience with burn patients with massive hemorrhage is not the equivalent of hemorrhagic shock in nonburned trauma patients who present with hypovolemic shock, acidemia, hypothermia, and coagulopathy. During burn wound excision, bleeding is simultaneously treated with fluid replacement, and measures are taken to support the circulation and prevent hypothermia.

Still, it is logical to assume that more aggressive use of fresh-frozen plasma to prevent development of coagulopathy can also benefit burn patients who experience massive hemorrhage. Maintaining body temperature in burned patients is especially important and challenging. The inflammatory response to large burns causes an increase in the hypothalamic core temperature set point.

The metabolic rate is increased to maintain this increased temperature. Hypothermia in these patients is poorly tolerated as it causes an exaggerated increase in oxygen consumption and exacerbates the catabolic response to the injuries. There are several critical postoperative concerns for burn patients: whether to extubate in the operating room, safe transport to the ICU, transfer of care to the ICU staff, and control of postoperative pain. The decision to extubate in the operating room depends on standard criteria with concerns specific to burn patients, including an assessment of airway patency, metabolic status, potential for ongoing bleeding, and when the patient will return again for surgery.

The same concerns regarding transfer from the ICU to the operating room apply for transfer back to the ICU, except that the patient is likely to be less stable physiologically in the postoperative period. Continued bleeding may be concealed by dressings, the patient may be more prone to hypothermia, emergence may be associated with delirium, and analgesic requirements will be greater. During this period of exaggerated physiological fragility, it is important to be especially vigilant during transfer of the monitors, respiratory, and hemodynamic support equipment to the ICU staff.

Inadequate control of pain and anxiety can adversely affect wound healing and psychological status. The presence of newly excised tissue and harvested donor sites are very painful. As indicated previously, it is common for burned patients to become quite tolerant of sedatives and analgesics over time, and thus, doses substantially larger than normal may be required especially in the postoperative period.

The optimal method providing sedation and analgesia in patients with major burns is still unresolved. All aspects of burn injury e. There is ongoing background pain, and there is procedure-related pain. Pain is exacerbated by anxiety if the pain is poorly controlled with sedatives and analgesics.

Pain of burns has hyperalgesic increased response to painful stimuli, e. Sensitivity to analgesics varies with time after burn injury from increased sensitivity and tolerance. The ideal characteristics of such a guideline include a safety and efficacy over a broad range of ages and burn injury severities, b explicit recommendations for drug selection, dosing, and increases in dosing, c a limited formulary to promote staff familiarity with drugs used, and d regular assessment of pain and anxiety levels with guidance for intervention through adjusted drug dosing.

Acetaminophen and nonsteroidal antiinflammatory drugs NSAIDs are useful first-line analgesic for minor burns. However, oral NSAIDs and acetaminophen exhibit a ceiling effect in their dose—response relationship, rendering them unsuitable for the treatment of severe burn pain. NSAIDs and benzodiazepines are commonly combined with opioids to relieve procedural pain.

Pain is exacerbated by anxiety, which may be reduced by benzodiazepines. Antidepressants appear to enhance opiate-induced analgesia, especially in patients with chronic neuropathic pain. The tolerance to opiates seems to be exaggerated by long-term administration of the benzodiazepine, midazolam. However, it can cause hypotension in higher doses and in the presence of hypovolemia, therefore should not be given to hemodynamically unstable patients.

Burn-injured patients frequently require surgical treatment, yet pose a myriad of pathophysiologic challenges to acute and perioperative care. Optimal care of the burn-injured patients requires a comprehensive preoperative assessment and attention to risk factors e.

Anticipation of these issues, as well as awareness of the alterations in pharmacokinetics and pharmacodynamics in patients with burn injury, is essential.

Significant losses of blood volume and body temperature are not uncommon sequelae in the intraoperative period.

Appropriate precautions should be taken to prevent these. Safe care can be provided by understanding, appreciating, and anticipating the unique preoperative, intraoperative, and postoperative issues and problems of the burn patient. Accessed May 16, Sign In or Create an Account. Advanced Search. Sign In. Skip Nav Destination Article Navigation. Close mobile search navigation Article navigation. Volume , Issue 2. Previous Article Next Article. Burn Injury Pathophysiology. Inhalation Injury.

Initial Evaluation and Management. Fluid Resuscitation. Electrical Injury. Anesthetic Management. Intraoperative Management. Postoperative Care. Pain Management. Competing Interests. Article Navigation. Education February Bittner, M. This Site. Google Scholar. Erik Shank, M. Lee Woodson, M. Jeevendra Martyn, M. Address correspondence to Dr. Information on purchasing reprints may be found at www. Author and Article Information. Submitted for publication March 5, Accepted for publication September 30, Anesthesiology February , Vol.

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Abstract Background The trinity of hypothermia, acidosis and coagulopathy, the lethal triad in trauma setting is a well-known risk factor associated with high risk of death.

This study aimed to study the occurrence and outcome of patients presenting with the 'triad of death' in burn population. Results One hundred and ninety-six patients were admitted during study period. The "on admission" acidosis, hypothermia, and coagulopathy were independently associated with significantly increased mortality.

Conclusion This study reiterates the fact that the lethal triad is seen in burn patient. Free full text. Indian J Crit Care Med. PMID: Author information Copyright and License information Disclaimer. This work is licensed under a Creative Commons Attribution 4. This article has been cited by other articles in PMC. Go to:. Background The trinity of hypothermia, acidosis and coagulopathy, the lethal triad in trauma setting is a well-known risk factor associated with high risk of death.

Keywords: Burns, Critical care, Lethal triad, Mortality. Study Setting The study was conducted at a premiere tertiary care center for burns in India. Data and Definitions Data for all eligible patients were collected at the time of admission and were recorded in a preformed template using Microsoft Excel Microsoft, USA with anonymity.

From the available literature, the following definitions were arrived at: Hypothermia was defined as a temperature of less than or equal to Acidosis was defined as pH of less than or equal to 7.

Statistical Analysis The population was divided into patients with and without the deadly triad. Open in a separate window. Flowchart Table 1 Demographics and characteristics of study population. Table 2 Relation of individual parameters of lethal triad on mortality. Source of support: Nil Conflict of interest: None.

Emerg Med J. Improving outcome in severe trauma: trauma systems and initial management—intubation, ventilation and resuscitation. Postgrad Med J. Ball C. Damage control resuscitation: history, theory and technique. Can J Surg. Lethal triad in severe burns. Management deficiencies and death preventability of road traffic fatalities before and after a new trauma care system in Victoria, Australia.

J Trauma. Body temperature of trauma patients on admission to hospital: a comparison of anaesthetised and non-anaesthetised patients. Injury-associated hypothermia: an analysis of the national trauma data bank. Acute traumatic coagulopathy. Correlation of metabolic acidosis with outcome following injury and its value as a scoring tool. World J Surg. Latenser BA.

Critical care of the burn patient: The first 48 hours. Critical Care Medicine. Lactate: early predictor of morbidity and mortality in patients with severe burns. The Association between hypothermia, prehospital cooling, and mortality in burn victims. Acad Emerg Med. A prospective study on the implications of a base deficit during fluid resuscitation.

J Burn Care Rehabil. Martini WZ. Coagulopathy by hypothermia and acidosis: mechanisms of thrombin generation and fibrinogen availability. Full text links Read article at publisher's site DOI : Smart citations by scite.

The number of the statements may be higher than the number of citations provided by EuropePMC if one paper cites another multiple times or lower if scite has not yet processed some of the citing articles. Parkland Formula The Parkland Forumula was one of the most commonly used strategies for burn fluid resuscitation.

At hours, the infusion should be lowered to the lowest amount possible to maintain hemodynamic stability. Avoid very rapid bolus administration at the onset of resuscitation as this likely forces large volumes of fluid out of the vessels and into the inflammed tissues to make tissues more edematous.

Over resuscitation can lead to edema, compartment syndrome and burn edema. Burn edema can adversely effect burn care and grafting. Conversely, dehydration can also adversely affeect burn grafts. There is limited evidence regarding the most appropriate resuscitation strategies.

A more conservative approach to fluid resuscitation is being advocated. Calculate from the time of injury, not the time of admission. Target fluid resuscitation to the end point of a urinary output of 0. Albumin has been part of fluid resuscitation in burn care since the 's. While recent controversy has emerged regarding its safety, a Cochrane Systematic Review did not find any mortality difference. Vasopressors may be considered if necessary to maintain perfusion pressures.

If vasopressors or required, sepsis should be ruled out. C aution: Burned patients who have also experienced trauma may have higher volume and blood product requirements. Burn injuries may mask other injuries. Blood products may be required after burn debridements.