Proper Support Key to Weaning Children from Mechanical Ventilation in the Home


Vol. 11 •Issue 4 • Page 24
Home Pathways

Proper Support Key to Weaning Children from Mechanical Ventilation in the Home

Frequently, the conditions for which infants and children require prolonged mechanical ventilation improve over time, allowing for gradual withdrawal of ventilatory support. This weaning usually occurs within the context of in-hospital care, but it can be accomplished safely in the home setting, as long as clear guidelines, in-home professional support and precise communication with the hospital-based medical team are established and maintained.

The physiologic need for mechanical ventilatory support persists as long as the output of the respiratory pump — which includes the respiratory centers of the central nervous system, the chest wall and muscles of respiration — fails to overcome the load imposed upon it by the lung parenchyma or airways. (See Figure 1, page 26.) Pump failure can be the result of insufficient respiratory drive, excessive compliance of the chest wall, respiratory muscle weakness or respiratory muscle fatigue. In addition, abnormalities of the gas exchange function of the lung also can result in respiratory failure.

These inadequacies of the respiratory pump can be magnified further by the functional and structural differences that exist between infants or young children and adults.1 These include: an apneic response to hypoxia in infants; a highly compliant chest wall that under normal circumstances doesn’t become as stiff as the lung until approximately 1 year of age;2 and inefficient use of the intercostal muscles in infants because of the shape of the infant chest wall and the horizontal orientation of the ribs.

To complicate matters further, pediatric patients often recover from chronic respiratory failure at the same time they’re expected to grow and to make developmental gains. Therefore, goals of pediatric weaning programs must include sustained somatic growth and acquisition of developmental milestones whenever appropriate. Overly aggressive weaning can result in growth delay or failure and intolerance for play or developmental therapies, even in the face of normal blood gas values.

INDICATORS OF WEANING SUCCESS

With few studies published examining the possible predictors of weaning success in adult patients who required mechanical ventilation for more than 14 days, even fewer studies have been performed in children with chronic respiratory failure. Measurements of respiratory muscle strength have been shown to be predictive of weaning success within four to five weeks of the test in 24 infants and children requiring mechanical ventilation for 15 to 342 days,3 but no larger studies in chronically ventilated children have corroborated these results.

While some studies have examined other indicators of weaning success in children with acute respiratory failure,4-6 no studies have assessed possible predictors, such as respiratory muscle endurance, rapid shallow breathing index, tension time index of the respiratory muscles or multiple physiologic measurements (i.e., the CROP index)7-9 in children requiring prolonged mechanical ventilation. To date, weaning of children from chronic mechanical ventilation involves a process based largely on clinical evaluation and a slow trial and reassessment process.

PATIENT SELECTION

When evaluating candidates for home weaning from mechanical ventilation, there are a number of things to keep in mind. To begin with, patients should be stable on their current level of ventilatory support and demonstrate a positive growth trend and stamina for periods of play or other activities. They also should be free from frequent respiratory illnesses, with parents or caregivers trained to assess their respiratory status.

Candidates for weaning usually include those children with diseases that improve or resolve over time. Complete liberation from mechanical ventilation, however, need not necessarily be the goal of a weaning program. Some patients with neuromuscular weakness, for instance, desire extended periods during the day in which they’re not tethered to a ventilator. Such periods facilitate bathing, performance of therapies or the normalization of activities for a school-aged child.

Infants with congenital central hypoventilation syndrome who require continuous mechanical ventilation might be able to wean off mechanical ventilation during wakeful hours when they grow older. In doing so, they could be candidates for tracheal decannulation and institution of noninvasive nocturnal ventilation.

A HOME VENTILATION PROGRAM

The Pulmonary Division of the Children’s Hospital of Philadelphia follows more than 200 children in the community who require partial or full-time mechanical ventilatory support. (See Figure 2, page 26.) In a 2.5-year period, 13 patients — two with central airway problems and 11 with chronic lung disease of infancy or bronchopulmonary dysplasia — weaned completely from mechanical ventilation. An additional 40 patients were either in the process of weaning or weaned as much as they possibly could. (See Figure 3, page 26.)

For those children who weaned completely, the median age at which home weaning began was 11 months, with a range of two to 102 months. Duration to complete liberation from mechanical ventilation was 9.8 + 3.8 (SD) months, and there was no correlation between the child’s age and the time it took to complete liberation (R = 0.195).

Weaning was accomplished by initiating brief periods of reduced ventilator support once or twice a day, with a return to baseline ventilator settings for the remainder of the day. If tolerated, pa-tients underwent a gradual increase in the duration of weaning trials or “sprints.” This approach attempted to exercise the child’s respiratory muscles for limited periods, while also allowing the muscles to rest and recover.

Depending on the baseline ventilator settings and the underlying cause of respiratory failure, trials might include: removal of mandatory breaths with provision of pressure support breaths and positive end-expiratory pressure; removal of all positive pressure breaths but maintenance of continuous positive airway pressure; or complete removal of all positive pressure support to a T-piece or artificial nose (heat-moisture exchanger). Bronchodilators, inhaled anti-inflammatory agents and oral diuretics were continued as indicated to optimize lung mechanics.

Tolerance to a reduction in ventilator support was first established at an office visit. After the reduction was made, the child was observed for 10 to 15 minutes with continuous pulse oximetry, capnography and physical assessment. Weaning trials were then instituted in the home with caregivers receiving guidelines on parameters to follow and instructions on reducing support. Clinical assessments, made by caregivers before, during and after the weaning trials, included measurements of heart rate and respiratory rate, assessment of breathing effort (e.g. presence of retractions or accessory muscle use), pulse oximetry and capnography.

Additional long-term assessments included noting the child’s stamina for periods of play, how much the child slept, the child’s weight and overall demeanor. Home caregivers or nurses were instructed to call the medical office each week, at which time the child’s progress was reviewed and the weaning plan was amended. Weaning trials were curtailed if either short- or long-term intolerance to the reduction in support was present. (See Table 1.)

WEANING RESULTS

Among those 13 children who weaned completely from mechanical ventilation, the home care plan regarding weaning was delayed or temporarily reversed on 49 occasions. (See Table 2.) There was a variety of reasons for this, the most common being acute respiratory illness. Once the illness was resolved, the weaning process resumed. Poor weight gain or weight loss also was an issue. Once that occurred, progression of weaning was halted and the nutritional plan was reviewed comprehensively. A target of 120 to 130 calories per kilogram of the child’s weight was established. Wean.ing resumed only when the child demonstrated a positive trend on the growth curve.

On three occasions, the tracheostomy tube was accidentally displaced and families had to perform an emergency tube change. After that, the home caregivers elected to withhold further attempts at weaning temporarily following those decan-nulation episodes. In one family, professional nursing support wasn’t available for several weeks, and the home ventilation team couldn’t rely upon the accuracy of the parents’ observations of the weaning trials. Weaning was temporarily suspended until a skilled nursing presence returned to the home, after which weaning trials resumed.

Table 1. Indicators of Weaning Intolerance
  • Increase in heart rate or respiratory rate of ³ 20 percent over baseline
  • Hypoxemia requiring an FiO2 > 0.40 to correct
  • ETCO2 > 48-50 torr (if baseline ETCO2 35 — 45 torr) or >10 percent increase over baseline (baseline ETCO2 > 45 torr)
  • Weight loss or poor weight gain
  • Decreased activity or stamina
  • Napping or sleeping more
  • Interference with eating
  • CONCLUSION

    Improvements in pediatric and neonatal intensive care over the last 35 years have led to a growing number of infants and children surviving life-threatening conditions and injuries, though many require mechanical ventilator support for months or years.

    Fortunately, programs that support ventilator-dependent children and their families have developed, not only in response to families’ desires to have their children at home, but also to the limited health care resources and economic pressures arising from the filling of acute intensive care beds.10

    Table 2. Causes for Delay or Reversal of Weaning in 13 Patients
    Reason Frequency of Occurrence
    Acute respiratory illness 30
    Weight loss or poor weight gain 9
    Decreased level of activity or increased respiratory effort 6
    Inadvertent decannulation 3
    Lack of professional input 1

    Although the factors that are responsible for the resolution of chronic respiratory failure in children are poorly understood, with careful clinical assessment and close communication between the home and hospital health care teams, liberation from chronic mechanical ventilation can be accomplished safely and successfully in the home setting.

    REFERENCES

    1. Watchko JF, Mayock DE, Standaert TA, Woodrum DE. The ventilatory pump: neonatal and developmental issues. Adv Pediatr. 1991;38:109-134.

    2. Papastamelos C, Panitch HB, England SE, Allen JL. Developmental changes in chest wall compliance in infancy and early childhood. J Appl Physiol. 1995;78:179-184.

    3. Gozal D, Shoseyov D, Keens TG. Inspiratory pressures with CO2 stimulation and weaning from mechanical .ventilation in children. Am Rev Respir Dis. 1993;147:256-261.

    4. Khan N, Brown A, Venkataraman ST. Predictors of extubation success and failure in mechanically ventilated infants and children. Crit Care Med. 1996;24:.1568-79.

    5. Baumeister BL, el-Khatib M, Smith PG, Blumer JL. Evaluation of predictors of weaning from mechanical ventilation in pediatric patients. Pediatr Pulmonol. 1997;24:344-352.

    6. Farias JA, Alia I, Esteban A, Golubicki AN, Olazarri FA. Weaning from mechanical ventilation in pediatric intensive care patients. Intensive Care Med. 1988;24:1070-75.

    7. Tobin MJ. Weaning from mechanical ventilation: what have we learned? Respiratory Care. 2000;45:417-431.

    8. Yang KL, Tobin MJ. A prospective study of indexes predicting the outcome of trials of weaning from mechanical ventilation. N Engl J Med. 1991;324:1445-50.

    9. Jubran A, Tobin MJ. Pathophysiologic basis of acute respiratory distress in patients who fail a trial of weaning from mechanical ventilation. Am J Respir Crit Care Med. 1997;155:906-915.

    10. Pilmer SL. Prolonged mechanical ventilation in children. Pediatr Clin North Am. 1994;41(3):473-512.

    Dr. Panitch is associate professor of pediatrics at the University of Pennsylvania School of Medicine. He is an attending physician, as well as director of the technology dependence program and director of clinical services in the division of pulmonary medicine, at the Children’s Hospital of Philadelphia. Dr. Panitch thanks Laura Miske, MSN, for her critical review of the manuscript, and Eileen Hickey, CRNP, Susan Kolb, CRNP, and Miske for their tireless efforts on behalf of children with chronic respiratory insufficiency.

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