Use of Decompressive Craniectomy After Severe Head Trauma

AORN Journal, March, 1999 by Jane Wick, James Wade, Daniel Rohrer, Oisin O'Neill

In the United States, a head injury occurs every seven seconds and an associated death every five minutes. This affects 200,000 people per year.(1) Almost half of all trauma deaths are due to head injuries. Equally important is the fact that an even larger number of patients with brain injuries--most young and otherwise healthy--are left permanently disabled.(2) An estimated 60% of trauma fatalities occur before patients can be admitted to the hospital (ie, 40% at the scene, 20% in the emergency department). Brain injuries occur at all ages, but the peak is in young adults between the ages of 15 and 24 years old, with men affected three to four times more often than women.(3) The cost of head injuries in terms of expense and human misery is exceeded by few other conditions.

Major strides have been made during the past three decades in reducing the morbidity and mortality of severe head injury from 50% in 1970 to approximately 36% in the 1980s.(4) These results correlate to larger availability and better application of emergency medical services and critical care methodologies.(5) In addition, health care providers at the Legacy Emanuel Hospital and Health Center trauma center in Portland, Ore, have noted a dramatic decrease in the incidence of head injury with the enforcement of seat belt and helmet laws.

THE GLASGOW COMA SCALE

From the onset, head injury diagnosis and management are linked to patient outcomes. Using the Glasgow Coma Scale (GCS), 80% of all head injuries are classified as mild (ie, GCS score between 13 and 15), 10% are classified as moderate (ie, GCS score between nine and 12), and the remaining 10% are classified as severe, scoring eight or less on the GCS (Figure 1).(6) A GCS score of eight or less has become the accepted definition of a comatose patient.(7) A GCS score of three, four, or five leads to a mortality rate of 76% as most patients scoring so low have severe cerebral compression and displacement with temporal lobe-tentorial herniation.(8) Patients with severe head injuries have fixed and dilated pupils, exhibit posturing, are unable to follow simple commands, and are insensitive to pain, even after cardiopulmonary stabilization. With these patients, a "wait and see" approach can be disastrous--prompt diagnosis and treatment are of utmost importance.

[Figure 1 ILLUSTRATION OMITTED]

When routine measures fail to alleviate cerebral swelling associated with traumatic brain injury, caregivers have few management options. Patients most often will die or survive in an extremely disabled state. Despite advances in understanding, monitoring, and treating cerebral hypertension, the outcome for patients with severe diffuse post-traumatic Cerebral edema remains poor.(9)

MANAGING SEVERE HEAD INJURIES

Most strategies for managing head injury rely on minimizing secondary brain injury by lowering intracranial pressure (ICP) and optimizing cerebral perfusion pressure (CPP) to greater than 70 mm Hg (Table 1)(10) Numerous studies report a significant correlation between elevated ICP and low CPP with poor outcomes. (11) As elevated ICP is a major predictor of mortality, it is logical that caregivers' maximum effort be directed toward preventing intracranial hypertension and optimizing CPP. Treatment options to achieve this include evacuating intracranial masses, using patient positioning, draining cerebral spinal fluid, administering osmotic diuretics, using vasopressors, inducing coma with barbiturates, and performing decompressive craniectomy.

Table 1

ADULT SEVERE BRAIN INJURY MANAGEMENT

Purpose

To standardize care of the severely brain injured patient from emergency room to hospital discharge, making use of the Brain Trauma Foundation 1995 Guidelines for the Management of Severe Head Injury and the trauma collaborative practice plan. Standardization of care will allow the most efficient application of predetermined therapies and interventions by all responsible staff members. Standardization also will allow potential efficacy or harm of new and/or experimental treatment regimens to become more clearly apparent.

I. Emergency department

A. Oxygenation

1. Targets: Oxygen saturation by pulse oximeter [is greater than] 95%/partial pressure of oxygen [is greater than] 70 mm Hg)

2. Methods

a) Patients with Glasgow Coma Scale (GCS) [is less than] 8 should be intubated in the field, en route, or as shortly after arrival as is practical.

b) A GCS [is greater than] 9: Oxygen supplementation by mask or nasal cannula.

c) A GCS between 9 and 12: Monitor carefully for decreasing level of consciousness, ability to maintain airway, or altered respiratory pattern. Be prepared to intubate patient.

3. Monitors

a) Pulse oximeter on all patients.

b) Arterial blood gases by femoral artery puncture by intern on arrival.

c) Arterial cannulation for all patients with GCS [is less than] 8 or in shock at any time, or placed on mechanical ventilation for reasons other than behavior control.

B. Ventilation (partial pressure of carbon dioxide [Pa[C0.sup.2]]): Excess hyperventilation when used "prophylactically," worsens outcome at three and six months. Normocarbia should be maintained in the absence of clinical evidence of herniation or cerebral edema (eg, pupillary dilatation or asymmetric reactivity, motor posturing, GCS [is less than] 6).