Managing Asthma Exacerbations in the Pediatric Population

Transcription

1 Managing Asthma Exacerbations in the Pediatric Population Tonya Cauley Weidman, MHS, PA-C, AE-C Departments of Allergy/Immunology and Pediatric and Adolescent Medicine

2 Assessment Pulmonary index based on five clinical variables: Respiratory rate, degree of wheezing, inspiratory to expiratory ratio, accessory muscle use, and oxygen saturation. Each variable is assigned a score from 0 to 3. Total scores range from 0 to 15. As a general rule, a score of 7 to 11 indicates an exacerbation of moderate severity and a score of 12 indicates a severe attack. However, the PIS may underestimate the degree of illness in an older child; bradypnea, caused by a prolonged expiratory phase, will result in fewer points for the respiratory rate component. It can be used to assess initial severity, judge response to treatment, and facilitate admission and discharge planning.

3 Assessment Nearly all patients with acute asthma have hypoxemia as a result of ventilationperfusion (V/Q) mismatch. Beta-2 agonists may worsen this mismatch by causing pulmonary vasodilation in areas of the lung that are poorly ventilated. Humidified oxygen should be provided as needed to maintain an oxygen saturation of 92 percent.

4 Pharmacology Inhaled short-acting beta 2-agonists are the mainstay of emergent treatment of acute asthma exacerbations Albuterol is the most widely used short-acting beta 2-agonist in the acute setting. Inhaled beta 2-agonists can be administered by nebulization or metered-dose inhaler with a spacer (MDI-S). These methods appear to be equally effective for children of all ages and with a wide range of illness severity.

5 Pharmacology Nebulizers vs MDI Advantages of SVN delivery compared to MDI-S the ability to simultaneously deliver humidified oxygen and ipatropium bromide passively administer drug therapy to a child in respiratory distress. Disadvantages when using SVNs up to 90 percent of drug remains in the machine or is lost to the atmosphere the portability of SVNs is limited by the need for an external power source the use of SVNs increases respiratory therapy costs since each treatment takes approximately 10 minutes to administer, compared to approximately 10 seconds per puff of inhaler with 30 to 60 seconds between

6 Pharmacology Continuous delivery Studies comparing continuous versus intermittent nebulized delivery of beta 2-agonists have found similar outcomes and side effect Continuous nebulizer therapy is less labor-intensive than intermittent nebulizer therapy, resulting in reduced respiratory therapy costs. Young children may not tolerate wearing a face mask for long periods of time. When administering inhaled beta 2-agonists, clinicians may begin with either intermittent or continuous administration. However, continuous therapy insures that the goal of three treatments within the first hour of care for moderately ill children is met. Therefore, continuous therapy is recommended over intermittently nebulized or MDI-S therapy for children who require multiple treatments in the first hour or for an extended period. The optimal dose for continuous albuterol nebulization therapy has not been determined. One dosing schedule stratified by weight is: For children who weigh 5 to 10 kg, the dose is 10 mg/hr For children who weigh 10 to 20 kg, the dose is 15 mg/hr For children who weigh >20 kg, the dose is 20 mg/hr

7 Pharmacology Ipatropium via SVN or MDI-S. MDI formulation should not be administered to patients with allergy to peanut or soy because it contains soy lecithin, which may precipitate an allergic reaction. <20kg microgram per dose >20kg microgram per dose May administer with each of the first three albuterol treatments. Alternatively, ipratropium may be administered with the second and third treatments If administered by MDI-S, the NAEPP guidelines recommend a dose of four to eight puffs (each puff is 18 microgram). The NAEPP guidelines also comment that the MDI dose is low and has not been studied in asthma exacerbations.

8 Pharmacology Glucocorticoids Early administration of systemic glucocorticoids reduced admission rates The benefit was more pronounced in those not receiving systemic glucocorticoids before ED presentation and in those with more severe asthma. Oral versus IV/IM The NAEPP guidelines suggest that oral administration of glucocorticoids is preferred to intravenous administration because oral administration is less invasive and the effects are equivalent. Intramuscular administration of glucocorticoids may be warranted in patients who vomit orally administered glucocorticoids, yet do not require an intravenous line for other purposes.

9 Pharmacology Oral prednisone - 2 mg/kg (maximum 60 mg) for 5 days Dexamethasone phosphate can be administered orally longer half-life than prednisone (36 to 72 hours versus 18 to 36 hours) dose is 0.6 mg/kg (maximum dose 16 mg) Methylprednisolone IV 1 to 2 mg/kg (maximum 60 mg).

10 Mild Exacerbation PIS <7: Albuterol inhalation therapy administered via small volume nebulizer (SVN) at a dose of 0.15 mg/kg (maximum 5 mg) or metered dose inhaler (MDI-S) at a dose of one-quarter to one-third puff/kg (maximum eight puffs). If repeated doses are needed, they should be given every 20 to 30 minutes for three doses. Administration of systemic glucocorticoids to those who fail to improve after one inhalation therapy

11 Moderate Exacerbation PIS 7-11 Administration of supplemental oxygen if oxygen saturation 92 percent in room air. Albuterol nebulization (0.15 mg/kg, maximum 5 mg) combined with ipratropium bromide (250 microgram/dose if <20 kg; 500 microgram/dose if >20 kg) every 20 to 30 minutes for three doses or continuously. Patients who have received three doses of intermittent therapy and require additional albuterol therapy may be treated intermittently every 30 to 45 minutes or may be switched to continuous therapy. Administration of systemic glucocorticoids after the first inhalation therapy Administration of IV magnesium sulfate (75 mg/kg, maximum 2.5 g administered over 20 minutes) if there is clinical deterioration despite treatment with beta 2-agonists, ipatropium bromide, and systemic glucocorticoids.

12 Severe Exacerbation Administration of supplemental oxygen if oxygen saturation is 92 percent in room air. Albuterol nebulization (0.15 mg/kg, maximum 5 mg) combined with ipatropium bromide (250 microgram/dose if <20 kg; 500 microgram/dose if >20 kg), every 20 to 30 minutes for three doses or continuously. Alternatively, epinephrine or terbutaline (0.01 ml/kg of a 1 mg/ml solution) with a maximum dose of 0.4 mg (0.4 ml) may be administered intramuscularly or subcutaneously for children with poor inspiratory flow or children who cannot cooperate with nebulized therapy Patients who have received three doses of intermittent therapy and require additional albuterol therapy may be treated intermittently every 30 to 45 minutes or may be switched to continuous therapy.

13 Severe Exacerbation Subsequent management depends upon response to initial therapy. For patients who improve after the initial treatment, the approach is as described above for moderate exacerbations. For patients with a poor response to initial treatment: Administration of IV methylprednisolone (1 to 2 mg/kg, maximum 125 mg). Administration of IV magnesium sulfate (75 mg/kg, maximum 2.5 g administered over 20 minutes). For patients who do not respond to these interventions, administration of IV terbutaline may be indicated: bolus with 10 microgram/kg over ten minutes, then 0.3 to 0.5 microgram/kg per minute; infusion may be increased by 0.5 microgram/kg per minute every 30 minutes to a maximum of 5 microgram/kg minute.

14 Admission Criteria Children who require beta 2-agonist therapy more often than every two to three hours, have not improved after administration of systemic glucocorticoids, or who require supplemental oxygen need to be admitted to the hospital. Other factors that may necessitate hospitalization include: A history of rapid progression of severity in past exacerbations Poor adherence with outpatient medication regimen Inadequate access to medical care Poor social support system at home

15 Assessment Patients must be evaluated upon admission, every one to two hours while on beta 2-agonist continuous therapy, and before and after intermittent treatments to determine their response to therapy. This evaluation should include an assessment of: Respiratory rate Accessory muscle use Air exchange Wheezing Inspiratory to expiratory ratio Pulse oximetry Patients with lack of response or worsening of these parameters need more frequent treatments. Patients who are stable but not significantly improved should continue on the same frequency of treatments. Patients with clear improvement of the above parameters should have the interval between their treatments increased. In addition to the regularly scheduled beta 2-agonist treatment, "as needed" treatments should be available for episodes of acute bronchospasm or worsening respiratory distress.

16 Assessment Respiratory rate 1 point for tachypnea (defined by RR >50 breaths per minute (BPM) in an infant, RR>40 BPM in a child, and RR>20 BPM in an adolescent). Accessory muscle use 1 point for suprasternal, subcostal, or intercostal retractions; 2 points for neck or abdominal muscle use. Air exchange 1 point for localized decrease in breath sounds; 2 points for multiple areas of decrease. Wheeze 0 points for no wheezing or end-expiratory wheeze; 1 point for wheezing during all of expiration; 2 points for wheezing during all of expiration and during inspiration. Inspiratory:Expiratory ratio 0 points for 1:2; 1 point for 1:3. If the score is 2, the treatment is given. The interval between treatments does not change and the patient is reassessed before the next scheduled treatment. If the score is <2, the treatment is not given, the clinical status is documented, and the child is reassessed one hour later. At reassessment, if the score is 2, the treatment is given and the interval changed accordingly;

17 Oxygen Patients receiving supplemental oxygen therapy should be monitored with continuous pulse oximetry. Oxygen saturation should be noted at the time of each patient assessment Small children should be placed on infant flow meters to allow accurate weaning below 1 L/min of flow. Depending upon the oxygen saturation, adjust as follows: 94 percent Decrease the flow rate by 1/4 L/minute for children who weigh <15 kg and by 1/2 L/minute for children who weigh 15 kg 91 to 94 percent Continue the same flow rate 90 percent Increase the flow rate to achieve a saturation of 91 to 94 percent Oxygen saturation should be rechecked 5 to 10 minutes after changes to the oxygen flow rate. Once patients are no longer receiving supplemental oxygen therapy, oximetry should be monitored 5 to 10 minutes after discontinuation just before the next SABA treatment while the child is sleeping for the first sleep period after discontinuation If the oxygen saturation remains 92 percent during these, pulse oximetry can be discontinued

18 Discharge Criteria Asthma symptoms and signs (and scores if available) are considered mild. No longer require supplemental oxygen. Receiving a treatment regimen that can be reasonably duplicated at home (they are tolerating oral medications and the frequency of inhalation treatments can be managed by the caregiver). If possible, patients should be observed in the hospital for at least one interval while receiving the treatments that will be prescribed after discharge. If patients have been receiving nebulized medications they may be changed to MDI-spacer upon discharge provided they can demonstrate proper technique. If spirometry is readily available and the patient can perform it, FEV1 should be greater than 70 percent of expected. Access to medications and appropriate follow-up have to be confirmed. Asthma education is complete.