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Marc G. Jeschke - Burn Care and Treatment A Practical Guide - 2013.pdf
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6 Critical Care of Burn Victims Including Inhalation Injury

71

 

 

6.2.1.3 Transfusion

Transfusion guidelines are currently being investigated and most like changed. The gold standard of 100 mg/dl has been questioned, and a large multicenter trial is ongoing and investigates transfusion thresholds 70 vs. 100 mg/dl. Our practice is to target a level of least 70 mg/dl, but if a patient is premorbid with impaired cardiac function or poor oxygen delivery, we consider reaching hemoglobin levels of 80Ð90 mg/dl.

6.2.1.4 Vasopressors

Vasopressors or inotropes can be used if indicated. Usually during the Þrst 8Ð12 h, vasopressors should be avoided as vasoconstriction can have adverse effects. However, dobutamine as an inotrope can improve cardiac function if CO or CI is low (<3 l/min/m2). Classical vasopressors epinephrine and norepinephrine should be used with caution. Vasopressin is becoming a possibility that is currently studied in various trials. In the critical care population, vasopressin did not improve outcome compared to catecholamines. In addition, there are case reports that have no beneÞt with vasopressin but with an increased incidence of adverse effects, which is usually associated with high doses of vasopressin (>2.4 IU). However, it appears that doses between 1.2 and 2.4 IU are relatively safe and can improve the blood pressure. Our center usually uses vasopressin as a second-line agent. Dopamine, another inotropic agent, is used by some but generally is not widely used for burns.

6.2.2Urine Output

Urinary output in the acute phase of a burn is indicative of adequate organ perfusion, and the suggested target is 0.5Ð1 cc/kg/h. In children, UOP is targeted to 1 cc/ kg/h. However, UOP is not always adequate and can be affected by the burn itself, infusion of antioxidants during resuscitation, and central or peripheral renal insufÞciency.

6.2.3CVP

CVP is a rough marker for preload and hence Þlling of the patient. Of importance is that CVP should be measured correctly at the level of the heart with a subclavian or jugular line in place. The range of an adequate CVP in burned adults is 4Ð8 mmHg, which is 2Ð6 mmHg in burned children.

6.2.4Respiration

Respiratory rate, respiratory effort, breath sounds, and skin color reßect oxygenation and provide objective measurements of breathing. A respiratory rate of less than 10 or greater than 60 is a sign of impending respiratory failure. Use of accessory

72

M.G. Jeschke

 

 

Table 6.2 Indication for intubation [2, 4]

 

Criteria

Value

PaO2 (mmHg)

<60

PaCO2 (mmHg)

>50 (acutely)

P/F ratio

<200

Respiratory/ventilatory failure

Impending

 

 

Upper airway edema

Severe

Severe facial burn

 

Burns over 40 % TBSA

 

 

 

Clinical signs of severe inhalation injury

 

 

 

muscles, manifested by supraclavicular, intercostal, subcostal, or sternal retractions, and the presence of grunting or nasal ßaring are signs of increased work of breathing. Auscultation of breath sounds provides a clinical determination of tidal volume. Skin color deteriorates from pink to pale, to mottled, and to blue as hypoxemia progresses. These signs must be followed throughout the primary survey to avoid respiratory failure. Patients with probable respiratory failure should receive rapid, aggressive, and deÞnitive airway management (Tables 6.2 and 6.3).

Oral intubation with the largest appropriate endotracheal tube is the preferred method for obtaining airway access and should be accomplished early if impending respiratory failure or ventilatory obstruction is anticipated.

Oxygen saturation in the initial phase but also during the later phase of hospitalization should be over 85Ð90. Respiratory should be 8Ð20 in adults and 14Ð38 in children.

Effective gas exchange should be determined in an arterial blood gas analysis. Targets for good oxygenation as well as organ perfusion are those with pH >7.25.

6.2.4.1 Ventilation Settings

The different modes of ventilation including high-frequency oscillation are all being investigated and tested. Detailed descriptions of the different modes are beyond the scope of this handbook. In short, PEEP is useful in supporting oxygenation. The level of PEEP required should be established by empirical trials and reevaluated on a regular basis. PEEP levels should start at 5 cmH2O and be increased in 2Ð3 cm increments. PEEP trials should be done to optimize oxygenation and cardiac output. The effectiveness of continuous positive airway pressure (CPAP) or PEEP is related to surface tension abnormalities and the marked tendency for atelectasis in these patients. Pressure control ventilation with permissive hypercapnia is the current preferred method of treatment for ventilated patients. If pulmonary edema continues, the amount of PEEP and of oxygen should be elevated so as to maintain adequate gas exchange. The use of high-frequency oscillating ventilators in the pressure control mode may also result in better removal of airway debris. Low tidal volumes (5Ð8 ml/ kg) with PEEP may be needed to improve oxygenation. Peak ßow rates should be adjusted as needed to satisfy patient inspiratory demands. For inspiratory/expiratory (I:E) ratio, the inspiratory time should be long enough to deliver the tidal volume at

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