Acute Severe Asthma	86
Krishan Chugh

A 6-year-old girl developed worsening of her asthma symptoms one early morning. Her mother administered her two puffs of salbutamol with spacer. Not seeing any improvement after 15 min, she gave her two more puffs and moved her to the neighborhood nursing home. At arrival there the pediatrician found her to be dyspnoeic, diaphoretic, and unable to talk in full sentences. Auscultation of the chest revealed B/L ronchi. Her SpO2 was 90%.

Acute severe asthma results from reversible airway obstruction mostly expiratory, with main reason of obstruction being bronchospasm due to various trigger factors (such as allergens or viral respiratory infection) and inflammation of the bronchi and smaller airways. This leads to progressive hypoxemia and hypercarbia requiring bronchodilator nebulizer therapy, systemically administered anti-inflammatory agents (steroids), and sometimes mechanical ventilation.

Step 1: Initial resuscitation

Assess airway, breathing, and circulation and take resuscitative measures as described in Chap. 78.

Step 2: Assess severity of the asthmatic attack (Table 86.1)

•The rapid assessment of a child with status asthmaticus should focus on determining the severity of airway obstruction.

•Wheezing, which reflects turbulent airflow in obstructed airways, is usually equally audible on both hemithoraces. Asymmetric wheezing may imply unilateral atelectasis, pneumothorax, or foreign body. Expiratory wheezing alone is

K. Chugh, M.D. (*)

Department of Pediatrics, Institute of Child Health, Sir Ganga Ram Hospital, New Delhi, India

e-mail: [e-mail]

R. Chawla and S. Todi (eds.), ICU Protocols: A stepwise approach,	691
DOI 10.1007/978-81-322-0535-7_86, © Springer India 2012

Table 86.1 Severity of asthma exacerbations
					Respiratory arrest
	Mild	Moderate		Severe	imminent
Breathing difficulty	On walking	On talking		At rest
		Infant softer
		Shorter cry		Infant stops feeding
		Difficult feeding
	Can lie down	Prefers sitting		Hunched forward
Talk in	Sentences	Phrases		Words
Alertness	May be agitated	Usually agitated		Usually agitated	Drowsy or confused
Respiratory rate	Increased	Increased		Increased
	Normal rate of breathing in awake children:
	Age	Normal rate
	<2 months	<60/min
	2–12 months	<50/min
	1–5 years	<40/min
	6–8 years	<30/min
Accessory muscles and	Usually present	Usually present	Usually present		Paradoxical thoracoab-
suprasternal retractions					dominal movement
Wheeze	Moderate, often only end	Loud	Usually loud		Absence of wheeze
	expiratory
Pulse/min	Mild tachycardia	Moderate	Severe tachycardia		Bradycardia
		tachycardia

692

Chugh .K

Guide to limits of normal pulse rate in children:

	Age	Normal rate
	2–12 months	<160/min
	1–2 years	<120/min
	2–8 years	<110/min
Pulsus paradoxus (can be	Absent	May be present	Often present	Absence suggests
observed on SpO2 monitor	<10 mmHg	10–20 mmHg	20–40 mmHg	respiratory muscle fatigue
waveform)
Peak expiratory flow rate	>80%	~60–80%	<60% predicted or
(PEFR)			personal best or response
After initial bronchodila-			lasts <2 h
tor % Predicted or %
personal best
PaO2 (on air)	Normal	>60 mmHg	<60 mmHg
			Possible cyanosis
And/or PaCO2	<45 mmHg	<45 mmHg	>45 mmHg
			Possible respiratory
			failure
SaO2% (on air)	>95%	91–95%	<90%

Hypercapnia (hypoventilation) develops more readily in young children than in adults and adolescents

Asthma Severe Acute 86

693

694	K. Chugh

found in mild-to-moderate illness, whereas expiratory plus inspiratory wheezing is present in moderate-to-severe status asthmaticus.

•The silent chest is an ominous sign and may indicate either pneumothorax or the complete absence of airflow due to severe airway obstruction and imminent respiratory failure.

•Blood gas analysis may support the clinical judgment of severity; an increasing

level of CO2 is an ominous sign. During a moderate asthma attack, a capillary blood gas analysis may be sufficient; in patients admitted to an intensive care unit, arterial blood gas analyses should be a routine. Sequential measurements are important as respiratory alkalosis with hypocarbia is common during the early phases of an asthma attack, while normalization and a subsequent increase

in the PaCO2 may be important indicators of clinical deterioration. Thus, a normal PaCO2 with even borderline low PaO2 indicates a phase of rising PaCO2, hence, need for more intensive therapy.

•A chest X-ray may be relevant in search for underlying complications such as pneumonia or air leakages.

Step 3: Review ongoing treatment

•Take into consideration the treatment that the child may have received in the past few hours. This helps us in deciding where in the treatment algorithm (Fig. 86.1) we should start. For example, in a child who has received several doses of salbutamol in the past 1 h, it may be futile to begin treatment at the top end of the algorithm.

Step 4: Start treatment (Fig. 86.1)

•Follow the algorithm for treatment.

•Generally children tolerate repeated doses of salbutamol very well and tachycardia as a side effect is less worrisome.

Step 5: Monitor closely

•At all stages, the child should be constantly monitored and escalation or deescalation of therapy should be done accordingly. For example, a child who is showing signs of exhaustion may have to be intubated straightaway even if IV b-agonist or aminophylline has not yet been tried.

Step 6: Further treatment

•Intravenous ketamine can be tried in children who are not improving on intravenous b-agonist, intravenous steroids, and supportive therapy. It is a sedative that has bronchodilator properties. Generally, it is started in the dose of 1 mg/kg/h after a loading dose of 1 mg/kg. The infusion can be increased to 3 mg/kg/h. However, all preparations should have been made for intubation and ventilation before starting IV ketamine.

86 Acute Severe Asthma	695

Management of Asthma Exacerbations In The Acute Care Setting

Initial assessment, Initial treatment (If in acute respiratory failure/ critical admit in PICU directly)

Reassess after 1 hour

Physical examination, PEF, O2 saturation and other tests as needed

Criteria for moderate episode:

PEF 60-80% predicted/personal best Physical examination: moderate symptoms, accessory muscle use

Treatment:

O2

Inhaled β2 agonist and inhaled anticholingergic every 60 min

Oral glucocorticosteroids

Continue treatment for 1-3 h, provided there is improvement

Criteria for severe episode:

History of risk factors for near fatal asthma PEF< 60% predicted/personal best

Physical examination: severe symptoms at rest, chest retraction

No improvement after initial treatment Treatment:

Inhaled B agonist and inhaled anticholingergic Systemic glucocorticosteroids

Reassess after 1-2 hr

Good response within 1-2 hr Response sustained 60 min after last

treatment

Physical examination normal: no distress PEF>70%

O2 saturation>95%

Improved: criteria for discharge home PEF>60% predicted/personal best Response Sustained on oral/inhaled medication

Home treatment:

Continue inhaled β2-agonist Consider, in most cases oral steroid

Consider adding a combination inhlaler Patient education:

Take medicine correctly Review action plan Close medical follow up

Incomplete response within 1-2 hr Risk factors for near –fatal asthma Physical examination: mild to moderate signs

PEF <60%

O2 saturation not improving

Admit to acute care setting

O2

Inhaled B agonist +/− antichlinergic Systemic glucocorticosteroid Intravenous magnesium

Monitor PEF,O2 saturation, pulse

Poor response within 1-2 hr

Risk factors for near fatal asthma Physical examination: symptoms severe, drowsiness, confusion PEF <30%

Pco2 > 45mmHg Po2< 60mmHg

Admit to intensive care

O2

Inhaled β2 agonist plus anticholinergic Intravenous glucocorticosteroids Consider intravenous β2 agonist Consider intravenous aminophylline Possible intubation and mechanical ventilation

Reassess at intervals

Poor response (see above)

Admit to intensive care

Incomplete response in 6-12 hr(see above)

Consider admission to intensive care

Improved

Fig. 86.1 Management of asthma exacerbations in the acute care setting

Step 7: Assess the need for intubation and ventilation

•Generally, decision to intubate and ventilate an asthmatic child is made on clinical grounds.

•Thus, cardiac arrest, respiratory arrest or severe bradypnea, extreme physical exhaustion, and altered sensorium are taken as absolute indications.