Page 1658 - Hall et al (2015) Principles of Critical Care-McGraw-Hill

CHAPTER 122: Electrical Trauma 1177

unstable level of consciousness cannot be attributed to changes second-
TABLE 122-2 Criteria for Transfer Out of intensive Care Unit
ary to electricity until any systemic hypoperfusion or surgically correct-
All of the following criteria need to be met for safe transfer at 48 h: able head trauma has been eliminated. The initial physical examination
1. Thermal injury/open wounds on less than 20% of the body surface area should also include a careful evaluation and documentation of both the
2. No evidence of inhalation injury or upper airway edema central and peripheral nervous systems. A paralyzed ventilated patient
may need EEG monitoring to assess for seizure activity. The manifesta-
3. Neurologic stability tion of neurologic deficits may be delayed, so these evaluations should
4. No cardiac dysrhythmia for 24-48 h, or cardiac rhythm stability documented by serial ECGs be repeated daily.
5. Hemodynamic stability for 24-48 h Appropriate tetanus prophylaxis is provided as delineated by the
American College of Surgeons Committee on Trauma guidelines.
6. Normal acid-base balance
Appropriate evaluation and management of corneal injury and tym-
7. Compartment syndrome diagnostically excluded or appropriately treated panic membrane rupture should be instituted.
8. Peak CPK serum level less than 400 U/L in first 48 h a
9. Clearance of urinary pigments (hemochromogens) CARDIAC
a See Ahrenholz et al. 3
Lethal ventricular dysrhythmias are a major cause of immediate mor-
tality from electrical injury. If an initial dysrhythmia is corrected and
the patient is hemodynamically stabilized, recurrence of a potentially
After the patient is stabilized, a complete history should be obtained fatal dysrhythmia is unusual unless a cardiac pathology exists. As stated
if possible, and a careful physical examination should be performed. earlier, it is important to remember that electrical injury victims who
Witnesses and family members often give pertinent information regard- require CPR because of a dysrhythmia should be given prolonged ACLS,
ing the accident as well as significant medical history. On physical as reports of complete functional survival after significant periods of
examination, particular attention should be paid not only to the sites of CPR do exist. 8
electrical contact but also to other areas of significant patient complaint. Close to 50% of patients exhibit electrocardiographic (ECG) changes
It is a misnomer to refer to electrical “entry” and “exit” sites. When the or rhythm disturbances after injury. The most common ECG alterations
electrical source is an alternating current (eg, a home 60 Hz electrical are nonspecific ST-T wave changes and sinus tachycardia, which usually
socket), any point of physical contact will carry the current in and out of revert with time. Most dysrhythmias are transient, and therapeutic inter-
the body at 120 times per second. The location of surface contact points, vention is rarely needed. The difficulty lies in identifying the existence
which usually are full-thickness burns, allows the physician to establish of new myocardial damage and determining its physiologic significance.
the most likely pathway of the current and the region(s) of potential Some patients may suffer long-term damage to the conductive system. 9
tissue damage. Obvious cutaneous injury is usually only the tip of a The usual clinical diagnostic criteria for myocardial infarction
large soft tissue injury (iceberg theory). During resuscitation, electrical include ECG changes and elevation of cardiac isoenzyme levels in a
trauma victims frequently require large volumes of isotonic intravenous setting compatible with myocardial ischemia. These pieces of evidence
fluids, in excess of calculated needs. These large fluid requirements are not reliable, however, in the circumstance of electrical injury. ECG
are due to considerable third-space losses secondary to deep or occult abnormalities after electrical trauma are common, temporary, and
tissue damage. Unlike purely thermal burn injuries, resuscitation usually physiologically insignificant. The levels of the creatine phos-
formulas such as the Parkland formula are not helpful guides to fluid phokinase (CPK) MB isoenzymes may be elevated owing to large-scale
10
management. Isotonic fluids should be given liberally, with the initial muscle damage and may give a false impression of myocardial damage.
goal of resuscitation being a urine output of between 0.5 and 1 mL/kg/h. Troponin levels may be more helpful to help delineate myocardial
11
Any electrolyte abnormalities should be corrected quickly. If serum injury. Clinical symptomatology of cardiac ischemia, which is subjec-
CPK is greater than 1000 and/or hemochromogens (such as myoglobin tive at the best of times, is usually not helpful in the face of multisystem
or free hemoglobin) are found in the urine, the rate of fluid administra- electrical trauma. The technetium 99m pyrophosphate scan has also
tion is increased to achieve a goal urine output of 1.5 to 2.0 mL/kg/h. been used to try to identify myocardial damage. However, transmural
Consideration should also be given to the alkalinization of the urine and myocardial damage is rare, and this test does not accurately assess non-
administration of mannitol. Alkalinization of the urine (to pH >6.5) transmural injury. Since diagnostic tests are not helpful and significant
may inhibit precipitation of myoglobin and hemoglobin in the renal col- myocardial injury is historically known to be unlikely, aggressive volume
lecting system. Mannitol, an osmotic diuretic, is generally used to aid resuscitation and surgical intervention should proceed as required. The
4,5
in diuresis, wash out myoglobin in the renal tubules and expand intra- exception to this principle is the patient who has been hemodynamically
vascular volume. The recommended dosage is 12.5 g administered as unstable as a result of congestive heart failure, malignant dysrhythmia,
6,7
an intravenous bolus. If hemochromogens persist in the urine after man- or clinically obvious myocardial ischemia.
nitol bolus therapy, then a mannitol infusion should be started at the The evaluation of these patients includes daily ECGs for 3 days follow-
rate of 12.5 g/h continuously until the urine clears of hemochromogens. ing injury as well as serial cardiac isoenzyme determinations. The results
Careful observation of electrolytes is required when a patient is treated of these tests are interpreted in light of the clinical situation. It has been
with continuous mannitol infusion. Loop diuretics should rarely, if ever, suggested that not all patients need to have continuous cardiac monitor-
be used to improve urine output in electrical injury patients. ing after injury unless they have a history of loss of consciousness, recur-
Reliable, large-bore intravenous access is essential, as well as arterial rent dysrhythmia in the field or emergency room, abnormal ECG on
blood pressure monitoring and a urinary catheter. There is no evidence admission, or other injuries that necessitate cardiac monitoring. 12
to support the routine use of pulmonary artery catheterization. It may be
helpful to view all victims of electrical trauma as potentially having mul- RENAL
tiple injuries. These patients should be evaluated as multisystem trauma
victims. A large percentage of high-voltage electrical trauma patients Renal dysfunction occurs in approximately 10% of patients who suffer
have either fallen from a height or been thrown by the force of the elec- high-voltage electrical trauma. The most frequent cause of renal dysfunc-
tric current. Cervical spine as well as other orthopedic injuries should tion, and the most easily treated, is hypovolemia. A common mistake is
be suspected and sought, and therapy initiated as appropriate. A falling to grossly underestimate the volume requirements in electrically injured
hematocrit or hemodynamic instability must be thoroughly investigated. patients. The extent of soft tissue damage and the resulting third-space
Changes found by the mental status examination must be explained. An losses are not always immediately apparent, so fluid resuscitation may be

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