Q=volumetric flow rate
μ=viscosity, lb·sec/in2
L=tube length, in.
R=tube radius, in.
Some risk factors have been identified for the development of this problem. Tight-fitting endotracheal tubes, movement of the head and neck while intubated, intubation for 1 h, and the presence of a URI may predispose the child to the development of postintubation croup [22, 24, 25]. Stridor usually develops soon after extubation and can worsen for several hours after it first is clinically apparent. In this case, the airway manipulations, including rigid bronchoscopy, are the causes of the stridor. In the situation where the SPO2 is not reading, it is important to administer a high FiO2. Without a reliable SPO2 measurement, one must rely on the clinical picture in evaluating the patient.
- 2.
Downes and Raphaely developed the croup score as an aid to the clinical evaluation of children with this syndrome, either due to infection or postintubation [26]. The score does not include the SPO2 measurement and uses clinical parameters to assign a score that reflects the severity of respiratory embarrassment. A score of 0 to 3 is given for each of five aspects of respiration: stridor, retractions, air entry, color (normal of cyanotic), and level of consciousness and a score derived (below). The higher the score, the more severe the respiratory compromise. While the determination of a croup score does help the clinician apply a more rigorous assessment to the child with stridor, the variables assessed are not independent. As the condition worsens, all variables will worsen together.
0 | 1 | 2 | |
|---|---|---|---|
Inspiratory breath sounds | Normal | Harsh with rhonchi | Delayed |
Stridor | None | Inspiratory | Inspiratory and expiratory |
Cough | None | Hoarse cry | Bark |
Retractions and flaring | None | Flaring and suprasternal retractions | Flaring and suprasternal retractions plus subcostal and intercostal retractions |
Cyanosis | None | In air | In 40 percent oxygen |
- 3.
Treatment of postintubation stridor includes the administration of dexamethasone (decadron), a potent, longer-acting glucocorticoid. This medication will act to limit the degree of inflammation and the severity of the subglottic edema. Decadron administration will not decrease edema already present, however [27, 28].
- 4.
Sedation should be avoided. Depression of respiratory drive is dangerous in this situation. Nebulized racemic epinephrine may help by actually decreasing the degree of subglottic edema. The duration of the effect is generally 1 h or less.
- 5.
Nebulized racemic epinephrine will act to decrease the subglottic edema. Once racemic epinephrine has been administered to a child with postintubation croup, the child should be admitted for observation with the expectation that subsequent doses will be needed. The usual dose of racemic epinephrine is 0.5 mL of the 2.25 % solution diluted into 3–5 ml of NS and administered via a nebulizer. The mask is held near the child’s face with 100 % oxygen used to nebulized the solution.
- 6.
In the event that reintubation is necessary, a smaller than normal endotracheal tube should be used. Intubating conditions should be as good as possible in order that the intubation cannot cause additional trauma. The narrowed part of the airway, the subglottis, will not be visible to the laryngoscopist, but if the tube meets resistance once the tip is beyond the vocal cords, a smaller diameter tube should be used.
Hyperthermia
Questions
You are called to the bedside of a 10-month-old who has just undergone a cleft palate repair. He has a temperature of 41.2oC.
- 1.
What might have happened that his temperature got to this point?
- 2.
Could this represent malignant hyperthermia? Why/why not?
Hyperthermia
Answers
- 1.
Postoperative hyperthermia usually is the result of excessive warming and is more common in pediatric patients than adult patients. In cases such as repair of cleft palate, the child is well covered by surgical drapes. If warming is undertaken during the case with devices such as forced hot air mattresses, warming blankets, humidification, and warming of inspired gases, the child’s core body temperature could easily rise to the level noted in the case here. Hyperthermia in the PACU that is the result of excessive warming in the OR generally dissipates rather quickly once the sources of additional heat are removed. If the elevated temperature persists, other causes must be sought.
- 2.
It is possible that the temperature elevation is part of a response to systemic infection. Of course, any case of temperature elevation should bring the possibility of malignant hyperthermia to mind. The anesthetic record should be reviewed to learn the time course of the temperature elevation and to review the medications administered during the anesthetic. It is likely that the child would have been exposed to potent inhaled agents during the anesthetic. The presentation described here would be quite unusual for malignant hyperthermia. Most cases of malignant hyperthermia develop within the first few hours of an anesthetic, but there are reports of MH occurring well after the conclusion of a case. It is also unusual for fever to be the presenting sign of an episode of MH. Often tachycardia, hypertension, and tachypnea are noted first. If the child in this case was developing MH, mottled skin and muscle rigidity would be expected. The most consistent laboratory finding in cases of MH is a combined respiratory and metabolic acidosis.
Annotated References
Desparmet JF, Hardartq RA, Yaster M. Central blocks in children and adolescents. Chapter 20. In pain in infants children and adolescents. 2nd ed. Philadelphia: Lippincott Williams & Wilkins; 2002. p. 339–62.Related posts:
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