Monitoring the burn patient during burn resuscitation….

 Doc, we recently had a patient with 80 percent burns. Though we calculated the fluid loss and replaced it adequately the patient died. Could you tell us why this may have happened?

Sohail k,

Karachi, Pakistan.

Patient with major burns have two major issues that need to be dealt with:

a) Calculating the fluid requirement and replacing it

b) Monitoring the burn patient to know if the fluids replacements are adequate

We have already seen the calculation of fluids requirements in a previous post. We shall have a look at how to monitor burn patients. With fluid replacements there can be two issues- inadequate fluid replacement or fluid overload. If the calculated fluids are less then the patient will end up in shock and deteriorate. If the fluids are over calculated then fluid overload, increased pulmonary complications and increased compartmental pressure will result and finally end in circulatory failure and collapse.

All burn patients must therefore be monitored with great care.  A number of clinical parameters that are commonly used in ICU monitored patients are also applicable here:

Pulse

Temperature

Respiration

Blood pressure

Oxygen saturation

Central venous pressure

 Hourly urine output

These are the most common clinical parameters used. As the body looses fluids from burns and the intravascular pressure falls from the fluids shifts the blood pressure tends to fall. However the human body has a lot of inbuilt mechanisms to control this fall and deceptively maintains the blood pressure by releasing catecholamines or chemicals which will cause contraction of the blood vessels and thereby maintain the blood pressure. The pulse also rises from the pain reaction (tachycardia). The body has a limit till which it can support the blood pressure, once the fluid loss crosses this limit the homeostatic mechanisms will fail and  burn shock will result. The increasing compartmental edema that results in burns can result in an erroneous blood pressure reading. Similarly the vasospasm that occurs in the extremities can lead to incorrect oxygen saturation reading by pulse oxymetry.

Urine output is one of the most important parameters while monitoring the burn patient and this should be 0.5ml (kg/hr) in adults and in children    about 1ml (kg/hr). In most cases if an adequate urine output is maintained one can assured of an adequate fluid resuscitation. Major burn patients will need placement of a urinary catheter to monitor the hourly urine output. The volume status can also be gained from the central venous pressure or CVP. Insertion of a cvp line helps in monitoring this pressure and helps prevent fluid overload in normal patients. However in patients with previous poor cardiac function or in geriatric patients one may need the use of a swan ganz catheter. Similarly diabetic patients and those using long term diuretics and also patients with resuscitation difficulties may benefit from the use of the swan ganz catheter. Pulmonary vasoconstriction may lead to faulty CVP or swan ganz measurements. Maintenance of the acid base balance in the body as seen from the various blood gas measurements and analysis suggest adequate resuscitation. Some patients with cardiac co morbidities may need invasive cardiac monitoring. In these patients one must be careful while increasing the fluid administered and should only be done gradually to maintain adequate urine output (0.5ml/kg/hr adult and 1ml/kg/hr in children).

The requirement of fluid may be higher than calculated in some patient groups. Those patients who have suffered inhalation injury need 30-40%more fluids than suggested by Parkland formula. Patients with electrical burns need more fluids as they have greater underlying tissue damage. Patients undergoing diuretic therapy have prior free water deficits and need more fluids for resuscitation. Patients who have undergone escharotomies and have large open wounds may have higher free water losses that need to be adequately replaced. Patients in whom resuscitation is delayed probably have higher inflammatory response, greater fluid needs and attempts should be made to replace the fluid deficit calculated by Parkland in the immediate resuscitation period without causing hemodynamic failure.

(An original initiative in burn care and education from asktheburnsurgeon++)