Caution: This Guideline describes management of Acute Asthma in PICU.

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1 Acute Asthma PICU Caution: This Guideline describes management of Acute Asthma in PICU. There is a separate guideline for the management of Acute Asthma within the General Ward/Pre-Critical Care setting, which can be found here. Title of Guideline Guideline on the management of acute asthma in PICU setting Contact Name and Job Title (author) Directorate & Speciality Dr T Ritzmann (ST3) Andrew Wignell Prof H Vyas Dr C Silvestre Date of submission of this one Feb 2014 Date when guideline to be reviewed Feb 2019 Guideline Number 1976 Explicit definition of patient group to which it applies (e.g. inclusion and exclusion criteria, diagnosis) Directorate: Family Health Children Speciality: PICU Life-threatening/acute severe asthma in PICU Abstract This guideline describes step-wise Asthma management in PICU Key Words Paediatrics; Children; Life-threatening Asthma; Acute severe asthma Statement of the evidence base of the guideline has the guideline been peer reviewed by colleagues? 1a meta analysis of randomised controlled trials 1b At least one well-designed controlled study X with randomisation 2a at least one well-designed controlled study without randomisation 2b at least one other type of well-designed quasiexperimental study 3 well designed non-experimental descriptive studies (ie comparative / correlation and case studies) 4 expert committee reports or opinions and / or clinical experiences of respected authorities 5 recommended best practise based on the clinical experience of the guideline developer Consultation Process PICU Guidelines Meeting Target audience Staff caring for patients with asthma in PICU setting This guideline has been registered with the trust. However, clinical guidelines are guidelines only. The interpretation and application of clinical guidelines will remain the responsibility of the individual clinician. If in doubt contact a senior colleague or expert. Caution is advised when using guidelines after the review date. Acute Asthma in PICU Page 1 Dec 2018

2 Document Control Document Amendment Record Version Issue Date Author V1 Feb 2014 Feb 2018 (V1b minor update only) Dr T Ritzmann (ST3) Andrew Wignell Prof H Vyas V2 Dec 2018 Dr T Ritzmann (ST3) Andrew Wignell Prof H Vyas Dr C Silvestre Summary of changes for new version: V1b - Minor update only to highlight awareness of separate Acute Asthma guidance for non-critical care areas V2 additional information regarding respiratory team referral and guidance regarding follow-up for patients with acute severe asthma, in line with updated Asthma guideline for general ward/pre-critical care areas Statement of Compliance with Child Health Guidelines SOP This guideline has had only minor changes made and therefore this version has not been circulated to all for review. The amendments added have had prior consultation by circulation to senior team members. Maria Moran Clinical Guideline Lead 12 Dec 2018 Acute Asthma in PICU Page 2 Dec 2018

3 Background Asthma is one of the most frequent causes of hospitalization among children in developed countries and one of the top indicators for admission to a PICU. The pathologic hallmarks of asthma are airway inflammation, excessive mucus production, mucus plugging and bronchospasm. All of these in combination lead to severe airflow obstruction and may result in respiratory failure. There are deaths from asthma in children each year in the UK (1 per 100,000 children). PICU mortality is generally low. Patients at risk of developing severe life-threatening asthma attack: Previous near-fatal asthma e.g. previous ventilation/icu admissions Requiring three or more classes of anti-asthma medications Heavy use of ß 2 agonists Repeated attendances at ED for asthma care especially in last year (Children who die are more likely to have visited hospital in the last year for their asthma). "Brittle" asthma Lack of perception of severity of attacks (e.g. children of African origin may have chemoreceptor insensitivity, older children are more at risk of having lack of perception of severity). Parental smoking Important points in the history: Assessment Chronic symptoms/poorly controlled asthma Previous life-threatening attacks/icu admissions Failure to respond to treatment/deterioration whilst on steroids Lack of perception of severity of attacks Social background (e.g. smoking at home, evidence of deprivation) Clinical (including investigations) It is essential to assess accurately the severity of symptoms on initial assessment. Assess for and record: Heart Rate Use of accessory muscles Oxygen saturations Respiratory Rate Degree of wheeze/air entry Conscious level/agitation Clinical Features of Assessment of Severity of Asthma Acute Severe Can t complete sentences in one breath or too breathless to talk or feed Pulse: > 5yr: >125, 2 5 yr >140 Respiration: > 5yr: >30, 2 5 yr >40 Peak flow: 33-50% of predicted Oxygen saturations <92% Life Threatening Silent Chest Cyanosis Poor respiratory effort Hypotension Exhaustion Confusion Peak flow <33% of predicted Oxygen saturations <92% Acute Asthma in PICU Page 3 Dec 2018

4 Occasionally clinical signs correlate poorly with the severity of airway obstruction. Some children with acute severe asthma do not appear distressed. Investigations Chest X-rays and ABG measurements are not routinely indicated. Indications for Chest X-ray Radiographic evidence of atelectasis is common in acute asthma but does not always imply infection. Post-intubation If suspicion of Pneumothorax or sudden deterioration The presence of subcutaneous emphysema. If suspicion of lobar collapse or consolidation Doubts regarding diagnosis Life-threatening asthma not responding to treatment PEFR measurements Not indicated in acute severe or life threatening asthma. However these measurements may be of use in those who are familiar with using such devices 1. We do not recommend the routine use of peak flow measurements. Blood Gas Clinical signs are more helpful. In Initial stages, expect Low PaCO2. Normal/High PaCO2 may indicate worsening of airway obstruction. Regular monitoring required following intubation and ventilation Patient may develop metabolic acidosis in acute severe asthma. Acidosis with high lactate may occur following ß 2 agonist treatment. Acute Asthma in PICU Page 4 Dec 2018

5 Summary of Management Flowchart Assess severity of presentation Provide calm reassurance Sit patient up Moderate - Severe Life threatening SpO2 > 92%: Inhaled salbutamol SpO2 < 92%: Nebulised salbutamol Administer high flow oxygen Oral prednisolone Nebulised salbutamol back to back Add nebulised ipratropium if no response after 20 minutes Nebulised ipratropium every 20 minutes No improvement or life threatening features after 10 mins: call PICU Consider the need for monitoring: Pulse oximetry and 3 lead ECG Obtain IV access Salbutamol bolus dose or infusion IV Magnesium sulphate IV Hydrocortisone OR Oral Prednisolone if not already given IV aminophylline loading dose and maintenance infusion Transfer to PICU if not done so already Refer to the respiratory team as soon as possible within working hours via respiratory Registrar (Do not wait until ready for step down). If admitted over the weekend and ready for discharge before Monday, notify General Paediatric Consultant.[ Acute Asthma in PICU Page 5 Dec 2018

6 Initial management Reassure patients and provide calm environment. The importance of this cannot be overemphasised. Position We strongly recommend sitting the patient up. Administer high flow O2 with aim to maintain saturations 94-98%. Monitoring Administer oxygen if saturations below 92% in moderate-severe asthma Irrespectively administer oxygen in life threatening asthma Pulse Oximetry 3 lead ECG to monitor for evidence of hypokalaemia Obtain intravenous access for: Blood sugar monitoring Measuring serum electrolytes IV Fluids IV medications/infusions A note about the use of intravenous fluids: Asthma can exert significant effects upon the cardiovascular system: In expiration there is decreased systemic venous return as a result of dynamic hyperinflation. In inspiration there is rapid right ventricular filling which can shift the interventricular septum to the left resulting in diastolic dysfunction and incomplete filling. In inspiration a large negative thoracic pressure is created decreasing systolic emptying thus increasing left ventricular afterload. Pulmonary artery pressure may be increased by hyperinflation increasing right ventricular afterload. Tachycardia resulting from hypoxia or as an effect of beta agonist use decreases diastolic filling time further, impairing the stroke volume and cardiac output. In addition to the above many patients are dehydrated at presentation owing to decreased intake and increased insensible losses. Adjust fluids according to input/output and electrolyte values. Do remember that patients may also be fluid overloaded despite the above, therefore consider fluid restriction if SIADH is suspected. Acute Asthma in PICU Page 6 Dec 2018

7 Pharmacotherapy The goal of pharmacotherapy is to ensure adequate oxygenation and ventilation and ease the work of breathing. The doses and administration instructions below are not a substitute for the BNF and should not be relied upon for prescribing purposes. Nebulised Salbutamol Dose: < 5 Years mg > 5 Years mg (1) Initial Drug Management Can be repeated every 20 minutes initially before stretching out the time interval between doses. If no improvement/deterioration --- Continuous Nebulized ß 2 agonist can be given (keep > 4mls solution in nebuliser pot) If symptoms are refractory to salbutamol add ipratropium bromide. Nebulised Ipratropium Dose: Child 1 month 11 years: 250 micrograms every minutes for the first 2 hours, then 250 micrograms every 4 6 hours as required. Child years: 500 micrograms every 4 6 hours as required. Corticosteroids Dose: Hydrocortisone 4 mg/kg IV (maximum 100 mg) 6 hourly. Change to oral Prednisolone 2 mg/kg daily (max 40mg) when the patient s condition improves. Children already receiving oral steroids as part of their chronic asthma management can have up to a maximum of 60mg. Duration : 3 5 days Inhaled steroids and leukotriene receptor antagonists have no role in the management of acute asthma exacerbations. If the patient is on these medications prior to admission, they can be omitted during the acute phase. (2) Subsequent Drug Management Children with continuing severe asthma despite frequent nebulised salbutamol, ipratropium and oral steroids or those with life threatening features need urgent PICU review and consideration of: IV Salbutamol IV Aminophylline IV Magnesium Sulphate Acute Asthma in PICU Page 7 Dec 2018

8 IV Salbutamol Dose: Bolus 15 microgram/kg (max 250 micrograms) over 10 minutes. Use the 200-microgram/ml solution. Continuous infusion 1 5 microgram/kg/min ( microgram/kg/hour) Consider the use of a bolus dose in severe cases not responding to inhaled therapy. Consider an infusion when there is uncertainty about reliable inhalation or there is severe refractory asthma. Continue nebulised therapy whilst the infusion is underway. infusion as the patient improves. This aids weaning of the IV Aminophylline Consider if asthma is unresponsive to maximal bronchodilators plus corticosteroids. Dose: Loading dose - 5 mg/kg IV over 20 minutes (omit in those receiving oral theophylline or who have received theophylline or aminophylline in previous 24 hours) Continuous infusion < 12 yrs mg/kg/hour > 12 yrs microgram/kg/hour Aminophylline is a CNS stimulant. It may contribute to difficulties in sedation of ventilated patients and can rarely precipitate seizures. Therapeutic monitoring of theophylline levels is imperative- see the PICU Pharmacopeia for details. IV Magnesium Sulphate Dose: Bolus 50% Magnesium Sulphate 0.2mmol/kg (0.1 ml/kg of 50% solution)- maximum 8mmol- over 20 min, diluted to 0.2mmol/mL in 0.9% saline or 5% Dextrose (dose range in literature is mmol/kg IV) Acute Asthma in PICU Page 8 Dec 2018

9 Role of Non-invasive Positive Pressure Ventilation In case series, treatment with NPPV has been associated with improved clinical and ventilatory parameters in children with asthma. Please see NIV (Non-invasive ventilation) guidelines for further information. Possible indications for NPPV In Children with acute severe exacerbation, NPPV may be used while awaiting the maximal therapeutic benefit of pharmacotherapy or may avoid intubation in few patients heading towards respiratory failure. Intubation and Mechanical Ventilation Intubation and mechanical ventilation should be considered for patients with progressive deterioration despite aggressive management. Mechanical ventilation in patients with acute severe/life-threatening asthma is challenging and not without complications. A decision to intubate and ventilate patient is clinical and not based on blood gas analysis. It should be discussed with the on-call PICU consultant. Indications for intubation: Apnoea Severe Dyspnoea Rising CO2 Frequent/Persistent low saturations inspite of maximum oxygen therapy Deteriorating consciousness level Deterioration despite aggressive treatment Aims of mechanical ventilation: To avoid barotrauma Minimize dynamic hyperinflation Maintain adequate oxygenation Allow recovery of bronchial inflammation bronchial constriction Intubation: 1. Intubation should be done by an experienced clinician as soon as signs of deterioration are present. 50% of complications surrounding the mechanical ventilation of asthmatics occur around intubation. Possible complications are due to gas trapping and include: worsening hypoxia hypotension pneumothorax and surgical emphysema cardiac / respiratory arrest 2. A cuffed endotracheal tube is preferred to minimize air leak with high inspiratory pressures, which may be required. Occasionally, cuff deflation may be required. 3. Rapid sequence intubation is the preferred technique. 4. Preoxygenation with 100% oxygen is must 5. Application of cricoid pressure during intubation should be used to reduce risk of aspiration. Acute Asthma in PICU Page 9 Dec 2018

10 6. Ketamine should be used as induction agent, as it has got bronchodilator properties (which appear within minutes) or Thiopentone. 7. Avoid rapid breaths when ventilating by bag. A slow bagging rate will give time for adequate expiration and avoid dynamic hyperinflation. 8. Keep Fluid bolus ready/easily available 9. Perform a chest x-ray after intubation to check for tube position and monitor for complications of intubation Starting mode of Ventilation: long expiration with slow rate BiPAP with ASB is used in patients with Status Asthmaticus. Initial Settings: Fio2 Start with 0.95, decreased as tolerated to maintain O2 sats > 92% Rate Set well below average physiologic rate for age (8-16/min) I:E ratio Must allow long expiratory time to avoid dynamic hyperinflation: eg. I:E Ratio of 1:3 to 1:5 PIP PEEP Possible guides to whether expiration is adequate before next breath: termination of wheeze, return to baseline on ventilator flow-time wave, return to plateau on capnography Likely to need high pressures aim to limit PIP < 35 cm H2O Avoid high PEEP as this may worsen dynamic hyperinflation. Initial PEEP should be 60% of intrinsic PEEP Permissive Hypercapnia Diminishing the risk of dynamic hyperinflation and barotrauma requires acceptance of PaCO2 higher than normal and ph lower than normal (ph > 7.2) Lower rates and tidal volumes can be used to achieve permissive hypercapnia. PaCO 2 up to 12 kpa can be allowed as long as the rise is not too rapid and the ph > 7.2 A rise is FiO2 is likely to occur when employing this strategy. Contraindications to permissive hypercapnia include: Raised Intracranial Pressure Poor myocardial function Significant Metabolic acidosis Possible pregnancy Pulmonary hypertension / right-sided heart failure. Sedation and Paralysis during mechanical ventilation: Sedation is used to promote patient/ventilator synchrony and blunt tachypnoea to reduce risk of barotrauma. Note that some patients may require very high levels of sedation. Ketamine with Midazolam should be used. 2 nd line Fentanyl and Midazolam Paralysis to be avoided if possible or to be used for minimum duration (<24 hours) and with daily holidays. Check CK levels regularly if prolonged paralysis required. Nebulised Bronchodilators during mechanical ventilation Acute Asthma in PICU Page 10 Dec 2018

11 Bronchodilators may be given by nebulizer circuit attached to ventilator circuit to deliver Salbutamol + Ipratropium. Avoid frequent disconnections. Refractory Hypoxaemia It is necessary to rule out atelectasis, pneumothorax, frequent β 2 agonist nebulisation and hypovolaemia as causes of hypoxia. In some patients, simply reducing sedation, reducing the rate of ventilator breaths and allowing more patient-synchronized pressure supported breaths (ASB) can improve oxygenation. It is worthwhile trying this before resorting to extraordinary treatments. In the absence of other causes, the most likely cause for the hypoxaemia is the underlying V/Q mismatch of asthma. Possible treatment strategies include: Prone patient Use of DNAase or Broncho-alveolar lavage has been tried to clear mucus plugging in extreme cases or lobar collapse Consider Manual Decompression to minimize hyperinflation Aim to increase serum Mg up to 2.5mmol/l. This can be achieved by giving repeated correction doses of 0.4mmol/kg over 4-6 hours (see Pharmacopeia). While corrections doses can be given more quickly, this does not achieve the desired rise in intracellular magnesium. It is also predisposes to hypotension. Inhalational anaesthetics: Isofluorane may be used as a bronchodilator but this requires a full-time anaesthetist. ECMO Indications for weaning ventilation include: Weaning Ventilation Good PaO2 in an FiO2 of 40% or less and a PIP of <35cmH20 Minimal atelectasis on CXR Decreased intrinsic PEEP (as measured by ventilator) Reduce the rate of ventilator breaths and allow more patient-synchronized pressure supported breaths (ASB). Follow-up of patients with Life threating asthma Refer to paediatric respiratory registrar for respiratory team assessment as early as possible Respiratory team to assess and decide re: ongoing management and follow-up If Patient is admitted over the weekend and ready for discharge before Monday- hot week general paediatric consultant to review and decide ongoing plans. Respiratory Nurses Debra Forster and Caroline Youle can be contacted by phone or (ChildrensRespiratoryNurses@nuh.nhs.uk) Acute Asthma in PICU Page 11 Dec 2018

12 References 1. British Thoracic Society Guidelines on Asthma. (2012 version). 2. Werner HA. Status Asthmaticus in Children: a review. Chest 2001 Jun;119(6): Beakes, DE. The use of anticholinergics in asthma. J Asthma 1997; 34: Bohn D, Kissoon N. Acute Asthma. Pediatr Crit Care Med 2001; 2: Maxwell, GM. The problem of mucus plugging in children with asthma. J Asthma 1985; 22: Cox RG, Barker GA, Bohn DJ. Efficacy, results and complications of mechanical ventilation in children with status asthmaticus. Pediatr Pulmonol 1991; 11: Bellomo R, McLoughlin P, Tai E, Parking G. Asthma requiring mechanical ventilation: a low morbidity approach. Chest 1994; 105: Dworkin G, Kattan M. Mechanical Ventilation for status asthmaticus in children. J Pediatr 1989; 114: Stewart TE, Slutsky AS. Occult, occult auto-peep in status asthmaticus. Crit Care Med 1996; 24: Stein R, Canny GJ, Bohn DJ et al. Severe acute asthma in a pediatric intensive care unit: a Six year s experience. Pediatrics 1989; 83: Carroll CL, Sala KA. Pediatric Status Asthmaticus. Crit Care Clin 29 (2013) Papiris S, Kotanidou A, Malagari K, Roussous C. Clinical review: Severe asthma. Critical Care. (2002) 6(1) Pitkin AD, Roberts CM, Wedzicha JA. Arterialised ear lobe blood gas samples: An underutilised technique. Thorax 1994;49: Non-invasive PPV 14. Carroll, CL, Schramm, CM. Noninvasive positive pressure ventilation for the treatment of status asthmaticus in children. Ann Allergy Asthma Immunol 2006; 96: Akingbola, OA, Simakajornboon, N, Hadley, Jr EF, Hopkins, RL. Noninvasive positivepressure ventilation in pediatric status asthmaticus. Pediatr Crit Care Med 2002; 3:181 Medications: Please refer to the PICU pharmacopoeia for more details of the medications (including how to prescribe them) used in the department. This can be found here: hnet/nuh_documents/lists/clinical%20a%20to%20z/paediatrics/paeds%20cc%20pharmac opeia Acute Asthma in PICU Page 12 Dec 2018

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Printed copies of this document may not be up to date, obtain the most recent version from Children s Acute Transport Service Clinical Guidelines Acute Severe Asthma Document Control Information Author E Randle Author Position CATS Consultant Document Owner E Polke Document Owner Position Co-ordinator