Asthma In Children

Management of acute Asthma in children Dr Mohd Nizam Mat Bah

Case 1        

5 yrs old boy 1st admission to the hospital Acute onset of wheezing Severe asthma Requiring ICU care Continous salbutamol nebuliser and infusion High flow oxygen; maintained Sat >95% Steroids

Case 1   



CXR: small pneumothorax Slowly recovered Transferred to general ward after 3 days in ICU Asthma Education before discharge

Case 2     

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7 years of age Known asthmatic, on prophylaxis Tachypnea and wheeze Admitted after 3 doses of nebuliser Well, mildly tachypnea only, speaks in full sentences Discharge with oral steroids

Acute management   

Confirmed the diagnosis Assess severity of asthma Managed according the severity

Severity asthma (1) 

Apprehensiveness



Unable to complete sentences in one breath



SaO2<92% in room air after three appropriate doses of inhaled salbutamol within 60 mins.

Severity of asthma (2) 

Tachycardia  

>130 in children aged 2-5 yr >120 in children aged >5 yr

Increasing tachycardia denotes worsening asthma or increasing doses of salbutamol

Severity of asthma (3) 

Tachypnoea:  >50 in children aged 2-5 yr  >30 in children aged >5 yr



Palpable pulsus paradoxus (equates to ≥15 mm Hg) NB all asthmatics have some degree of pulsus paradoxus at rest.

Pulmonary Index Score: score

0

1

2

3

dyspnoea

absent

mild dyspnoea: normal activity and speech

moderate dyspnoea: decreased activity; 5-8 word sentences

severe dyspnoea: concentrates on breathing; 0-5 word sentences

accessory muscle use

no

intercostal and suprasternal retractions

nasal flaring

wheeze

none

terminal expiratory

panexpiratory

insp. & expiratory or audible without stethoscope or silent

inspiratory:expirator y ratio

I = 2.5 × E

I = 1.5 × E

I=E

I<E

intercostal retracti retractions on

Pulmonary index score 

 

Calculate pulmonary index by adding up score (0-3) for each category. Maximum score 12, minimum score 0. A PIS of ≥ 7 is consistent with severe asthma

Respiratory failure score 0

Oxygenation PaO2 or SaO2

In air 65-100 mm Hg or 90-97%

1

In air <70 mm Hg or <90%

2

In 40 % oxygen <70 mm Hg or <90%

Inspiratory breath sounds

Normal

Unequal

Decreased or absent

Use of accessory muscles

None

Moderate

Maximal

Expiratory wheeze

None

Moderate

Marked

Cerebral function

Normal

Reduced or agitated

Poorly responsive or coma

Respiratory failure score 

Calculate respiratory failure score by adding up score (0-2) for each category.



Maximum score 10, minimum score 0.



Acute Respiratory failure is consistent with a score of > 5, together with a PaCO2 >45 mm Hg.

Modified dyspnea scale

Dyspnoea score Severity 0

Absent dyspnoea

1

Normal activity and speech; minimal dyspnoea

2

Decreased activity; 5-8 word sentences; moderate dyspnoea

3

Concentrates on breathing; <5 word sentences; severe dyspnoea

Progressive worsening: 1. Agitation and Confusion 2. Exhaustion 3. Cyanosis 4. Increasing tachycardia. 

5.

NB Decreasing heart rate is pre-terminal

Poor respiratory effort

Note: •

Wheezing may be less apparent with increasing airway obstruction, with a silent chest occurring in life threatening asthma.

•

Clinical signs correlate poorly with severity of airway obstruction. Thus objective measurements with SaO2 are essential.

•

PEF measurement rarely provides additional useful information.

•

CXR may be abnormal but does not usually guide management. A pneumothorax may be revealed in severe respiratory failure.

•

Blood gases rarely guide therapy. A rising pCO2 may be indicative of worsening respiratory failure, but the decision to intubate is still a clinical one

How to access the severity of acute asthma Mild Altered consciousness

No

Physical Exhaustion

No

Talks In

Sentence

Pulsus Paradoxus

Not palpable

Central Cyanosis

Absent

Wheeze on auscultation

Present

Use of accessory muscles

Absent

Sternal retraction

Absent

Initial PEF (%predicted or % Child’s best)

>60%

Oximetry (prior nebuliser)

>93%

10/23/08

Moderate

Henry et al, J Paediatr Child Hlth 1993; 29:101-103

Severe

How to access the severity of acute asthma Mild

Moderate

Altered consciousness

No

No

Physical Exhaustion

No

No

Talks In

Sentence

Phrases

Pulsus Paradoxus

Not palpable

May be

Central Cyanosis

Absent

Absent

Wheeze on auscultation

Present

Present

Use of accessory muscles

Absent

Moderate

Sternal retraction

Absent

Moderate

Initial PEF (%predicted or % Child’s best)

>60%

40-60%

Oximetry (prior nebuliser)

>93%

91-93%

10/23/08

Henry et al, J Paediatr Child Hlth 1993; 29:101-103

Severe

How to access the severity of acute asthma Mild

Moderate

Severe

Altered consciousness

No

No

Yes

Physical Exhaustion

No

No

Yes

Talks In

Sentence

Phrases

Words

Pulsus Paradoxus

Not palpable

May be

palpable

Central Cyanosis

Absent

Absent

Present

Wheeze on auscultation

Present

Present

Silent

Use of accessory muscles

Absent

Moderate

Marked

Sternal retraction

Absent

Moderate

Marked

Initial PEF (%predicted or % Child’s best)

>60%

40-60%

<40%

Oximetry (prior nebuliser)

>93%

91-93%

90% and below

10/23/08

Henry et al, J Paediatr Child Hlth 1993; 29:101-103

Management of severe asthma: Aims: 

 

Maintenance of adequate oxygenation (SaO2 ≥ 93%). Rapid bronchodilation Treatment of haemodynamic compromise

Maintained adequate oxygenation

Oxygen delivery is best by high flow oxygen via reservoir fitted facial mask (thereby increasing FiO2), with the aim of maintaining SaO2 ≥ 93%.

What are the consequences of hypoxaemia? 





Resp:  Bronchoconstriction. CVS:  Hypertension  Decreased systemic oxygen transport  Increased myocardial oxygen consumption. Neuro:  Reduced level of consciousness, agitation, confusion

Maintained hemodynamic stability 

With acute asthma there is an increased metabolic rate and insensible respiratory fluid losses as well as decreased oral fluid intake.



This may lead to dehydration in addition to increasingly viscous airway secretions (with intraluminal airway plugging).



Humidification of inspired gas and adequate hydration is indicated.

Maintained hemodynamic stability 

If adequately hydrated, 2/3rds of the child’s maintenance requirement should be given because of the possibility of inappropriate antidiuretic hormone secretion.



Serum electrolytes should be measured and hypokalaemia corrected if detected.



Supplemental potassium (to a total of 2-3 mmol/kg/day) in IV fluid therapy is recommended during regular beta-2 agonist use.

Bronchodilation 

Receiving beta-2 agonists continuously via a nebuliser is the preferred option in severe asthma. Use 2.5 mg for infants, 5 mg for older children, diluted to 4 ml with 0.9% saline.



In between nebulisations change to a Hudson mask with rebreather

.

bag

Bronchodilation 1.

Frequent beta-2 agonist use can lead to the side effects that include tachycardia, tremors, agitation, paradoxical bronchospasm, hyperglycaemia and hypokalaemia.

Salbutamol infusion: 

Use undiluted salbutamol 1mg/ml.



Starting dose is 5 mcg/kg/hr for at least one hour. This is likely to achieve adequate blood levels for maximal bronchodilation.



Increments should be 2.5 mcg/kg/hr, up to a maximum of 10 mcg/kg/hr (consult intensivist if a higher dose is considered).

Salbutamol infusion 

After adequate response and stability decrement should be to 3 mcg/kg/hr, then 1 mcg/kg/hr.



The adverse effects include hypokalaemia, hyperglycaemia and lactic acidosis, which are mild

Salbutamol infusion There is probably no added benefit in continuing nebulised salbutamol concomitantly (so inhalations may be ceased, especially at night), but during the weaning phase reintroducing nebulised salbutamol at 1 hourly intervals is a sensible transition process



IV adrenaline should be used in prepubertal children only in life threatening acute attacks or in the presence of anaphylactic shock.



The theoretical advantage of adrenaline over other sympathomimetic agents lies in its added “alpha effects”, from which mucosal vasoconstriction may reduce oedema.



In older children IV adrenaline is a (cheaper) alternative to IV salbutamol

Steroids 

Oral and intravenous steroids are of similar efficacy.



The intravenous route does not offer any advantage over the oral route unless the child has nausea &/or vomiting.



Benefits of systemic steroids can be apparent within three to four hours, with maximal effect obtained 6 to 12 hours after administration.



Dose is prednisolone or methylprednisolone 2 mg/kg/day. Switch to oral once on hourly nebulised salbutamol, if tolerated



Ipratropium Bromide 

There is evidence for the efficacy of frequent doses of ipratropium bromide (an anticholinergic) in addition to inhaled beta-2 agonist

Algorithm for management of acute asthma in children Mild improved Nebulised B2 Agonist

No improvement

Observe for 60 min -discharge with Long term plan Asthma action plan

moderate Nebulised B2 agonist 3 doses At 20 min intervals +O2 (8L via face mask) +/- oral steroids +/- Ipratropium bromide Admit if no improvement

improved

Observe for futher 60 min; discharge With B2 agonist +/Oral steroids Long term plan Asthma action plan

Algorithm for management of acute asthma in children

SEVERE

Nebulised B2 Agonist Every 20 min or continously + steroids (oral/IV)

Continuous observation

Consider: Parenteral B2 agonist IV aminophylline Intensive care Unit

Improved: Continuous observation

Summary of management of acute asthma 

Confirm the diagnosis 



History, examination

Assess the severity:   

Mild ? Moderate? Severe?

When to refer: Severe asthma- needs ICU care Stabilize patient

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