status asthmaticus - critical careold.criticalcare.org.za/images/15h05_giles_fri_plenary.pdf ·...

Status Asthmaticus

B. Louise Giles MD FRCPC

2 Status Asthmaticus |

Status Asthmaticus: Objectives VTAS 2015

• Define status asthmaticus

• Describe the problem (epidemiology)

• Understand the pathophysiology of status asthmaticus

• Know the treatment options

• Have an understanding of status asthmaticus management outside the guidelines

• Have an understanding of prevention strategies, and the barriers to treatment

Disclosures VTAS 2015

• Chair: Comer Children’s Hospital Asthma Quality Committee

• Member: AsthmaNet

• Member: CAPriCORN

• Member: CHICAGO 1 trial

• No financial interests


Scenario 1 VTAS 2015

• 3 yo Caucasian female

• PMHx of mild asthma – no prior exacerbations

• ED: 1-2 day hx of viral URTI (cough, rhinorrhea, worsening dyspnea)

– Tachypneic (RR >40), hypoxic (SpO2 85%)

– “silent chest”

– Management: β2 agonist; Steroids; Mg; ipratropium bromide

– BiPAP initiated

• PICU: Type 2 respiratory failure (pCO2 > 50)

– Intubated, ventilated

– Systemic β2 agonist; aminophylline

– Anesthesia (ketamine; inhaled)

– ECMO


Scenario 2 VTAS 2015

• 15 yo African American male

• PMHx of severe asthma – previous PICU admissions

• Has not seen a Respirologist; non-compliant with “controller” medication; takes SABA

daily

• S/S of viral URTI <12 hours; increases use of SABA

• Parent decides to take to local ER

• Collapses

• No pulse, CPR initiated, EMS activated

• Asystole. Full resuscitation including epinephrine, CPR

• Resuscitation - unsuccessful


What is this… VTAS 2015



Asthma: A review VTAS 2015

Chronic illness Narrow airways

Most often starts in childhood

Wheeze, cough,

chest tightness,

short of breath

Mild - Severe

Treatment

multi-modal


Asthma: USA VTAS 2015

• Asthma in USA

• >10 million children have asthma; 25 million overall

• Death rate increasing (in children)

• Nine Americans die daily from Asthma

• >2/3 have had an asthma exacerbation in the past 12 months

• Leading cause of school absence (>14 million school days lost/year)

• Costs 5-14% of income to the family

• Highest prevalence in African American children


Asthma: Chicago VTAS 2015

• Asthma in Chicago

• Mortality due to asthma 5x higher in African American (non-Hispanic vs. White non-

Hispanic)

• Hospitalization rate double national average

• >50% of children with asthma had exacerbation in the past year

• 28%of people with asthma awoken with breathing problems weekly

• Almost 60% of children with asthma live with a smoker

Asthma: South Africa VTAS 2015


• Mortality: One of the highest reported mortality rate worldwide (GINA)

• ~3.9 million South Africans with asthma

• ~20% of school age children have asthma

• 3rd most common cause of hospital admissions in children

• Treatment & education is key

– Estimated only ~2% receive treatment

Asthma – worldwide prevalence VTAS 2015


Asthma deaths - worldwide VTAS 2015



Status Asthmaticus VTAS 2015

Asthma exacerbations VTAS 2015


Status asthmaticus VTAS 2015

• Acute

• Doesn’t respond to the “standard” treatment (SABA & ICS)

• Leads to …

– Respiratory insufficiency

– Circulatory failure

• Pathophysiology:

– Bronchoconstriction

– Mucous plugging

– Airways inflammation



• Type I (Slow onset)

– Inadequate treatment (provider, patient, other)

– Poor control

– Progressive – already using SABA’s

– Poor response

• Type II (Rapid onset)

– Sudden, occurs within hours

– Severe bronchospasm, minimal inflammation & edema

– “Silent chest”

– Responds quickly



• Complications:

– Airleak (↑ intrathoracic pressure)

– Myocardial infarction (hypotension, ↑ intrathoracic pressure)

– Atelectasis (mucous plugging)

– Electrolyte disorders (salbutamol)

– Myopathy & rhabdomyolysis (steroids & neuromuscular blockers)

– Lactic acidosis (cell injury)

– Anoxic brain injury


What are the guidelines for management VTAS 2015

• Overall …. Prevention

For exacerbation/status asthmaticus

• Supplemental oxygen – correct hypoxemia

• Short acting β2 agonists – bronchodilation

• Inhaled anti-cholinergics – bronchodilation

• Systemic steroids – anti-inflammatory


But what if they “don’t work?” VTAS 2015

• Systemic bronchodilators

• High flow O2

• Anesthetics

• Heliox

• NIPPV

• Intubation/mechanical ventilation

• Inhalational anesthetics

• ECMO


Systemic bronchodilators VTAS 2015

• β2 agonists: IV salbutamol; terbutaline

• Magnesium

• Methylxanthines


Mechanism of action of bronchodilators VTAS 2015


B2 – increases cAMP

A2 – prevents AcH release

MA– block AcH

XO – prevent breakdown

cAMP

Mg– block Ca; inhibit

AcH release

High Flow Oxygen (HFO)/High Flow Nasal Cannula (HFNC) VTAS 2015

• Delivery of oxygen at a rate that exceeds patients inspiratory flow

• Air/oxygen blend; Heated, humidified (37C; 100%); delivery tube heated

• Nasal cannula (ensure that occlusion of nares <50%)

• Flow rates up to 60 lpm (usual nasal airflow adults ~ 12 lpm at rest; 30 lpm with

respiratory distress)

• Benefits:

– Increased FiO2

Anatomic O2 reservoir

Wash out dead space

– CPAP effect

• Decrease atelectasis

• Decrease WOB/intrinsic PEEP

– Patient comfort

• Tolerated as heated, humidified


Heliox VTAS 2015

• Mixture of helium with oxygen (20-40%)

• Lower resistance – less turbulent airflow

• Helpful to bring inhaled medication to lower airways

• No evidence that this works…

– If hypoxic, not really helpful as need enough supplemental O2 (if FiO2

requirements >40%, shouldn’t use)


BiPAP VTAS 2015

• Reduces work of breathing/dyspnea

– Helps with auto-PEEP

– iPAP relieves work against airway resistance

• Retains spontaneous breathing

– Reduces intubation

• Retains cough

• Comfort


Intubation/mechanical ventilation VTAS 2015

• Oxygenate/ventilate

• Minimize barotrauma

– PRVC mode

– Know the auto-PEEP

– VT 5ml/kg (start) & watch the auto-PEEP

– Set PEEP to match auto-PEEP

– RR – must allow for full expiration- may mean lower RR (resist temptation to

increase the rate)


Meds “outside” the box VTAS 2015

• NaHCO3:

– Correct metabolic acidosis

– No clinical trials examining use

• Ketamine:

– Inhibits re-uptake of norepinephrine

– May be used to prevent intubation – low dose


• Inhalation anesthetics:

– Halothane, sevoflurane & isoflurane

– Lowers vagal tone



ECMO VTAS 2015

• “Hail Mary” – rescue & nothing to lose


http://www.pic2fly.com/ECMO+Machines.html

Improved survival (>80% for asthma

vs.~50% non-asthma respiratory

failure)

No guidelines

Case studies suggest that early use

may be beneficial

Prevention VTAS 2015

• All patients who have been in an ICU with asthma – Respirologist/Pulmonologist

– If intubated for asthma – increased mortality due to asthma for 10 years!

• Education is key… and South Africa has asthma education resources!!

– National Asthma Education Programme (www.asthma.co.za)

– Asthma Action Plans (USA –tracks hospital rates of providing an asthma action

plan or home management plan of care & this is a mandatory reportable QI

measure)


http://www.asthma.co.za/

Barriers to prevention VTAS 2015

• Education

– “I can’t have asthma”

• Feels better

– “I don’t have symptoms anymore so I don’t need medicines”

• Poor perceiver of symptoms

– “I don’t have symptoms”

• Economics

– “I can’t afford my medications”


Resources VTAS 2015

• Status Asthmaticus:

– Curr Opin Pulm Med, 2008;14:13-23

– Paed Resp Rev, 2013 Jun;14(2):78-85

• BiPAP:

– Curr Opin Pulm Med, 2014; 20(1):118-123

– Cochrane Rev, 2012; 12

• ECMO:

– J. Med Cases, 2011: 2(3):124-126

– J.Asthma, 2011; 48:111-113


Thank you VTAS 2015

• Our Challenge – prevention!

• Questions?

[email protected]

[email protected]


mailto:[email protected]


Thank you VTAS 2015

• Our Challenge – prevention!

• Questions?

[email protected]

[email protected]




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