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Fluid resuscitation in burns patients 2: Nursing care

Abstract
Williams, C.
(2008) Fluid resuscitation in burn patients 2: nursing care. Nursing Times; 104: 15, 24–25.
This is the second in a two-part unit on caring for patients with burns. Part 1 focused on the two formulas used to calculate fluid resuscitation. This part discusses the nurse’s role in managing patients with burns.

Author
Catherine Williams, PGCE, MSc, BSc, DipN, RNT, RN
, is nurse tutor, school of health science, Swansea University.

Learning objective

  1. Identify the care burn patients require, and the complications of inadequate fluid resuscitation

  2. Recognise signs and symptoms of burn encephalopathy in infants, children and adolescents

The most common question asked about fluid resuscitation is how much fluid to give. It is important to remember that formulas are only a guide and fluid adequacy should be assessed at the end of each period. Fluid loss can be massive in a patient with burns and relates to the size of the burn rather than its severity. The goal is to achieve a balance between restoring adequate tissue perfusion while minimising oedema formation.

If the loss from circulation is large enough, the patient will present with the following symptoms:

  • Pallor, sweating, thirst;

  • Anxious, disorientated state;

  • Collapsed veins, poor refill;

  • Tachycardia and weak pulse;

  • Hypotension and tachypnoea;

  • Oliguria.

Rapid boluses are discouraged as they temporarily increase hydrostatic pressure and increase the rate of fluid loss into the burn.

Measuring adequacy

The adequacy of fluid resuscitation is measured by clinical parameters, not simply by following a predetermined formula calculation. The recording of vital signs is generally made hourly but changes in a patient’s condition may necessitate more frequent recordings. Monitoring during this acute phase needs to include the following:

  • Monitoring of vital signs/haemodynamic parameters (such as central venous pressure, arterial blood pressure);

  • Heart rate;

  • Mean arterial pressure;

  • Signs of circulation in general (showing adequate fluid resuscitation), such as skin colour/perfusion and tissue perfusion;

  • Ventilatory parameters – for example changes in tidal volumes, minute volumes, spontaneous tidal and minute volumes, end tidal CO2, breathing rate and tube position;

  • Airway management;

  • Core peripheral temperature;

  • Signs of visceral circulation;

  • Urine output – aim for: adults 0.5ml/kg/hr = 30–50ml/hr; children (<30kg) 1.0ml/kg/hr (range 0.5–2.0ml/kg/hr) – children’s fluid requirements are greater;

  • Gut function (observe for gastric distension in children);

  • Blood tests – haemoglobin (Hb)/haematocrit (Hct) blood products may be required following surgical debridement;

  • Electrolytes within normal ranges, especially potassium and sodium;

  • Arterial blood gases;

  • Absence of metabolic acidosis – blood pH below 7.35 confirms the condition. Levels of other blood components, including potassium, glucose, ketones or lactic acid, may also be above normal ranges;

  • Burns dressing for signs of bleeding;

  • The patient’s general condition.

Urine output

If urine is kept at the above level then organ perfusion is adequate. Large urine output indicates unnecessary oedema formation, while a low urine output indicates poor tissue perfusion, likely cellular injury and hypovolaemia. However, if a diuretic is used during the resuscitation period then hourly volumes can no longer be used to measure the adequacy of fluid resuscitation.

Complications

Nurses must be aware of and report the following complications:

  • Electrolyte disturbances;

  • Red cell loss;

  • Renal failure;

  • Peptic ulcers;

  • Acute respiratory distress syndrome (ARDS);

  • Burn encephalopathy;

  • Hyponatraemia.

There are times when indicators in a patient’s condition mean alterations in fluid resuscitation requirements may be necessary. These include:

Inhalation injury: When this accompanies thermal trauma, it increases the magnitude of total body injury and requires increased volumes of fluid and sodium to achieve resuscitation from early burn shock (Navar, 1985). These patients often require 40–50% more fluid, whatever resuscitation regimen is used (Yowler and Fratianne, 2000). However, due to this increase patients are at risk of developing pulmonary oedema. Reducing the fluid to avoid this may result in inadequate cardiac output and lung perfusion, which can impair ventilation perfusion.

Associated trauma: As burn injuries are often accompanied by other traumatic injuries and patients are at risk of internal bleeding, they may require increased fluid due to hypovolaemic shock.

High-voltage electrical injury: This requires more fluid due to the release of myoglobin and haemoglobin from damaged cells which collect in the renal tubules causing acute renal tubular necrosis. These patients usually have to double urine output to flush the kidneys of large myoglobin cells.

Extensive deep burns: Patients with full-thickness burn/circumferential burns requiring escharotomies (a surgical incision into a burn eschar in order to lessen its pull on surrounding tissue) need more fluid as blood is lost from the escharotomies.

Pre-existing medical conditions: Alcohol/drug abuse. Patients intoxicated with alcohol at the time of injury often require increased fluid as alcohol acts as a diuretic.

Age groups: Careful monitoring of fluid resuscitation is critical in older adults, as they are more likely to have pre-existing long-term and/or cardiac conditions and general immune incompetence. These conditions pose an additional challenge for fluid management. This group is more susceptible to cardiac failure and pulmonary oedema and large volumes of fluid may precipitate this.

Children have a higher rate of water turnover, proportionally higher water load presented to the kidneys and a lower urine concentrating capacity, which all pose a challenge. Intravenous cannulation can be difficult and alternatives may need to be sought.

Consequences of inadequate fluid resuscitation

Delayed or under-resuscitation:

  • Renal tubular necrosis, acute renal failure;

  • Conversion of partial-thickness wound to full-thickness wound;

  • Formation of stress ulcers in the gastrointestinal tract.

Over-resuscitation:

  • Pulmonary oedema and related complications;

  • Excessive wound oedema with subsequent decreased perfusion to burns and unburnt tissues.

Burn encephalopathy

Resuscitation therapy must be more precise in the severely burnt child than in adults. Even short delays in starting fluid resuscitation can precipitate profound shock in a young child.

Generally, when a burn or a scald involves a child aged under five, there is usually no difficulty in balancing fluid loss by oral intake. There is, however, a requirement for salt and it is highly dangerous to attempt resuscitation by the normal fluid intake of water, flavoured drinks and so on, as this will result in severe hyponatraemia with possibly fatal consequences. Hyponatraemic encephalopathy is a serious complication and children are particularly susceptible to developing neurological complications, usually 3–4 days post injury.

A major consequence of hyponatraemia is the influx of water into the intracellular space, resulting in cellular swelling, which can cause cerebral oedema, seizures and brain stem herniation. This is due to the reduced space for brain swelling in the skull and because the paediatric brain is less able than the adult to adapt to hyponatraemia.

If hyponatremia develops, intracellular over-hydration will occur that can lead to complications due to complex metabolic, haematological and haemodynamic abnormalities (Hockenberry et al, 2003).

Strict monitoring of fluid intake and output is essential. Salt-free solutions are not recommended for children with a burn injury (Durward and Tibby, 2005).

Paediatric manifestations of encephalopathy from a burn injury include:

  • Cerebral irritability;

  • Hyperpyrexia;

  • Vomiting;

  • Twitching;

  • Convulsions and coma.

Prevention of this complication requires thoughtful control of fluid and electrolyte balance. If this does occur, then it should be slowly and carefully corrected. Rapid correction will result in an osmotic drive between extracellular and intracellular compartments, producing an increase of water to the cells.

Nursing action

Adequate fluid management is critical for survival from a major burn injury. Knowledge of fluid management following a major burn is very important and often overlooked in burns management education. Inadequate fluid replacement in major burns is common when clinicians lack sufficient knowledge and experience in this area.

All the resuscitation fluid formulas are guidelines. Their success relies on adjusting the amount of fluid against patients’ monitored physiological parameters. The amount of fluid depends on severity of the injury, age, physiological status and any associated injury.

Because the greatest plasma loss occurs in the first 24 hours post burn, the greatest replacement needs to occur in that period.

In optimising fluid resuscitation, the amount of fluid should be just enough to maintain vital organ function without producing pathological changes.

The effectiveness of fluid resuscitation therapy in correcting deficits and preventing complications should be reviewed at frequent intervals and continually observed.

It is unwise to rely on one physiological variable as an index of effective fluid resuscitation – instead a combination of variables should be used. Monitoring methods should be relevant to the fluid regimen used.

There is no question that replacement of the extracellular salt loss into the burnt tissue and into the cell is essential for successful resuscitation. Whichever formula is used to calculate fluid requirements, it should be adapted to individual patients.

Key references

Durward, A., Tibby, S.M. (2005) Hospital-induced hyponatremia. The Journal of Pediatrics; 147: 2, 273.

Hockenberry, M.J. et al (2003) Wong’s Nursing Care of Children and Young People. St. Louis, MO: Mosby.

Yowler, C.J., Fratianne, R.B. (2000) Current status of burn resuscitation. Clinics in Plastic Surgery; 27: 1, 1–10.

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