Acute wheeze: escalation to intravenous therapy for Acute Wheeze Integrated Care Pathway (ICP) for patients over 2 years old (1128)

Wheeze severity assessment

'Red Flag features

• Has the patient previously received IV therapy for wheeze management?
  
  
• Has the patient been admitted to the PICU previously for respiratory illness?
  
  

If YES to any of the above then patient should be discussed with on call Paediatric Registrar prior to discharge.

Drugs

Salbutamol MDI + Spacer – Initial therapy = 10 puffs.  (100mcg per puff)

Oxygen – minimum 6 l/min via non-rebreather mask

IV MEDICATION
(To be prescribed as per the Escalation to IV therapy care pathway)

Discharge criteria & checklist

• Patient maintaining saturations > 94% in air
• Tolerating 3hrly multidosing        

Patients with MILD asthma at 1^st assessment can be discharged after Salbutamol without being monitored for 4 hours

• Discharge Checklist Completed
• No red flag features
• If presenting with interval symptoms medication reviewed and consideration given to starting Clenil Modulite 100mcg BD
• Follow-Up arranged as below

• Failure to respond to initial therapy as per GGC ‘Acute wheeze’ guideline
• Assessing Response
• Consider Escalation to Intravenous Therapy
• Escalation to IV therapy – drug algorithms
  • Magnesium Sulphate
  • Aminophylline
  • Salbutamol
• Monitoring – including drug levels – timing and actions to levels 
• When to de-escalate care & referral to Respiratory Services criteria.
• Other care considerations – CXR and Virology sampling.
• Safe transfer criteria
• Estimated Weight Chart

• Give high flow oxygen via tight fitting face mask to achieve saturations 94% or above
• Continuous monitoring of heart rate and oxygen saturation
• Continue nebulised Salbutamol therapy
• Ensure the child has received oral steroids
  (if oral steroids not tolerated, see IV hydrocortisone below)
• If a child is already on daily steroids increase the dose to 2mg/kg (maximum 60mg)
• Assess response to initial treatment

Please document history and examination in ‘Acute Wheeze pro-forma’

Does the child meet criteria for Severe or Life-threatening Asthma?

*Peak Expiratory Flow readings should be used in children who have previously used a Peak Flow meter. Falsely low readings can be obtained in patients not used to the technique

IF YES THEN CONTINUE WITH FOLLOWING GUIDANCE

DOES THIS PATIENT REQUIRE IV THERAPY FOR WHEEZE?

• Have they failed to show any improvement or deteriorated since their presentation (taking into account severity at presentation)?
• Do they have a significant or increasing oxygen requirement?
  A small decrease in oxygen saturation is common after initial bronchodilator therapy and should be taken in the context of clinical condition and response to treatment.
  Significant hypoxia is indicative of severe asthma
  (SpO2 <92% in air, or >6l/min oxygen to maintain normal saturation)
• Do they have increased work of breathing (severe or life threatening)?
• Do they have significantly reduced air entry or silent chest?
• Are there clinical signs of exhaustion?

RECORD CLINICAL PARAMETERS AND COMPLETE THE FOLLOWING:

• Heart rate / Respiratory rate / Conscious level / Blood Pressure
• Oxygen saturation (And note oxygen requirement in L/min)
• Continue with oxygen delivered nebulised therapies.
• Site IV cannula and take a blood gas and U&Es.
  CO2 > 6kPa on venous gas is likely to indicate CO2 retention.
  (if IV access challenging – CBG can be utilised as 1^st line assessment).
• Patients requiring intravenous infusions for management asthma should have continuous cardiac monitoring (3 lead)
• If oral steroids were not tolerated give IV hydrocortisone as per weight (weight unknown use table below) and prescribe - 6 hourly dosing.

Raised lactate (>4) can be indicative of impaired oxygen delivery (due to poor gas exchange) or excess beta-adrenergic stimulation causing metabolic acidosis. It should be taken in the context of other clinical observations

1. Magnesium Sulphate (MgSO₄)

Drug dose

The dose is 40mg/kg or 0.16mmols/kg (max. 2 grams)

Drug Preparation

Draw up 0.08mls/kg 50% Magnesium Sulphate (40mg/kg) and dilute to 50mls with 0.9% saline
Run over 20-30 minutes.

ASSESS RESPONSE

If response to intravenous magnesium sulphate is felt to be poor, document the clinical parameters and relevant examination findings.  
Then proceed to 2^nd IV therapy – Aminophylline

2. IV AMINOPHYLLINE

Drug dose

The LOADING dose of aminophylline is 5mg/kg 
(5mls/kg of 1mg/ml solution) over 20 minutes (Maximum dose 500mg).

Aminophylline LOADING should be prescribed using actual body weight unless  patient is obese then use ideal body weight (see end of document)

Patients who are on theophylline should have a level taken and should not receive a loading dose.

All patients being given IV Aminophylline must be on continuous cardiac monitoring.

Drug preparation

Add 20mls of aminophylline 25mg/ml to 480mls of 0.9% sodium chloride to give a concentration of 1mg/ml.

Aminophylline is compatible with I.V. fluids which contain potassium; maintenance I.V. fluids can be connected via a y-connector.

ASSESS RESPONSE

Clinical review essential post LOADING to assess need for ongoing INFUSION.
Document clinical parameters and relevant examination findings.  

If ongoing need for INFUSION, inform PICU to ensure patient is added to the 'Watcher list' - PICU Fellow: 84725

INFUSION Dose:  ideal body weight for height (See BNFc for guidance chart).  

Drug preparation

As per loading dose drug preparation above.

IV SALBUTAMOL

Salbutamol for injection comes in 2 concentrations: 
500 micrograms in 1ml or 5mg in 5ml (1mg/ml). 
Use the correct concentration for LOADING  and INFUSION dosing.

LOADING DOSE

Drug dose 

The LOADING dose of salbutamol is 15 micrograms/kg  (maximum 250 micrograms) slow injection over 5-10 minutes.

Drug Preparation

Use 500 micrograms in 1ml concentration for LOADING preparation

For intravenous injection dilute to a concentration of 50microgram/ml with

0.9% NaCl by adding 9mls to 1ml of 500microgram/ml salbutamol injection

Example

For any child over 16kgs then loading dose is maximum 250 micrograms

15kg child – LOADING dose = 15 x15mg = 225micrograms –
Solution diluted to 50microgram/ml. Give the 4. 5mls final solution over 5-10 minutes

INFUSION DOSE

Drug dose 

INFUSION dose for salbutamol is 1-5micrograms/kg/min.  Rates should be adjusted according to response.

In the Royal Hospital for Children, IV salbutamol is a PICU LEVEL  DRUG, infusions can be started pending transfer but doses of >2micrograms/kg/minute should not be given outside PICU.

Drug Preparation 

Use 5mg in 5ml (1mg/ml) concentration for INFUSION preparation
Dilute to a concentration of 200micrograms per ml with 0.9% saline (add 40mls of 0.9% saline to 10mls of salbutamol 5mg/5ml to give 10mg (10,000micrograms) in 50mls)

Example

20kg child – infusion dose is 2microgram/kg/min  =40microgram/kg/min
Solution is 200microgram/ml – 40/200 =0.2. Run at 0.2 mls/min (12mls/hr)

If IV SALBUTAMOL required then Treating Consultant should be present and PICU contacted asking for URGENT REVIEW (84725). 

Children with severe asthma requiring intravenous therapy are high dependency (HDU) patients requiring close monitoring.  Under our current pathway these patients would initially be admitted to CDU or PICU.

Continuous ECG and saturation monitoring is necessary for patients on aminophylline and/or salbutamol infusions.  

• Standard clinical observations should be recorded on PEWS chart every 5 minutes for the first 15 mins and if improving then at 15 minutely intervals for the first hour.
• Observations, including BP should be recorded hourly until the patient is felt to be improving.
• CBG /VBG should be repeated as clinically indicated.
• U&Es should be conducted minimum of every 12 hours for patients on IV infusions.

CLINICAL REVIEW REQUIREMENTS

After starting an intravenous infusion the child should be reviewed (by physician or ANP) a minimum of every 30 minutes for the first 2 hours and as clinically indicated thereafter.

The following should be recorded in medical notes with each review:

• Conscious Level.
• Oxygen saturations and oxygen requirement in litres/minute.
  Significant hypoxia (SpO₂ <92%, or significant oxygen requirement >6l/min to maintain normal oxygen saturation) is indicative of severe asthma.
• Heart rate – Compare to normal range for age.
  Increasing tachycardia generally denotes worsening asthma but remember that B2agonists increase heart rate. 
  In life-threatening asthma a drop in heart rate can be a pre-terminal sign
• Blood Pressure
• Respiratory Rate – Compare to normal range for age.
• Posture / position of patient.
• Ability to talk in words, phrases or sentences
• Degree of Respiratory Distress / Use of accessory muscle and recession
• Air entry - including any clinical suspicion of pneumothorax or significant collapse and amount of wheezing including biphasic or silent chest

Example of expected format of documentation of clinical review: 

“Alert and orientated with saturations of 95% in 5L O2.
HR: 125 beats per minutes. RR: 32 breaths per minute.
Sitting forwards and speaking in short sentences.
Moderate subcostal and intercostal recession with tracheal tug.
Air entry is reduced bilaterally at the bases with biphasic wheeze  throughout.”

Possible Side Effects of Intravenous Aminophylline

• Muscle tremors
• Tachycardia and palpitations
• Nausea and vomiting
• Agitation
• High doses can cause peripheral vasodilatation which can result in hypotension. Please see guidance for aminophylline in obese patients.

If a child develops a significant metabolic or lactic acidosis, without an increase in respiratory effort or oxygen requirement check an aminophylline level and adjust the infusion.  

Indication for taking Aminophylline Levels

The BNFc recommends aiming for theophylline levels of 10-20mg/L. There is very little evidence for this range in children³

For children in the RHC, Glasgow; we do not recommend routine theophylline levels for patients on aminophylline infusions.

In these circumstances a level should be taken and sent to biochemistry urgently.   These patients require a senior review.

DOSE ADJUSTMENT GUIDANCE:

POOR RESPONSE but no concern about toxicity:

< 5mg/L
Check the prescription and cannula site. 
Repeat loading dose and leave the infusion running at the same rate.  After this adjustment, if the patient is improving there is no need to check a further level.

5-<10mg/L
Repeat half-loading dose and leave the infusion running at the same rate. After this adjustment, if the patient is improving there is no need to check a further level 

10-<12.5mg/L
Increase the infusion rate by 20%. After this adjustment, if the patient is improving and there are no signs of toxicity there is no need to check a further level

12.5mg/L -17.5mg/L
Increase the infusion rate by 10%. After this adjustment, if the patient is improving there is no need to check a further level.

> 17.5mg/L
Continue aminophylline infusion at the same rate. Urgent PICU review for consideration of intravenous salbutamol

Concern patient demonstrating signs of TOXICITY:

>20mg/L and clinical signs of toxicity (see above)
Withhold infusion for 4 hours and recheck level before restarting infusion; if intravenous therapy still required urgent PICU review for consideration of intravenous salbutamol

In all instances, failure of an adequate response to aminophylline requires urgent PICU review and consideration of intravenous salbutamol (irrespective of the aminophylline level)

Remember that if a child is improving care can be de-escalated at any time
(Note: The half-life of aminophylline is 3-5 hours)

Criteria for reducing aminophylline: 

• Normal ability to speak
• No increase in respiratory effort
• Reduction in oxygen requirement
• Significant improvement in peak flow
• Aminophylline rate should be halved and reviewed again for discontinuation after 6 hours
  Some patients may require a slower reduction and aminophylline rate should then be halved every 6 hours.
• The decision to reduce and discontinue aminophylline should be clearly documented in the notes. The change in rate and discontinuation of aminophylline needs to be documented (with timing) on the infusion chart.

Rebound bronchospasm can occur as aminophylline is reduced and stopped.
Nebulised salbutamol and ipatropium bromide should be continued during this process - consider 2 hourly nebulised salbutamol.

Patients who have required intravenous therapy for wheeze should be monitored in hospital for at least 24 hours post the discontinuation of all intravenous therapy.

All patients requiring intravenous therapy for wheeze should be referred as an in-patient to the respiratory team and the asthma specialist nurse (via TrakCare) in order for appropriate follow-up to be arranged.

Chest X-Ray

Chest x-rays are not routinely recommended in asthma.

If there is clinical concern about a pneumothorax or doubt about the diagnosis; a chest x-ray should be performed.

Virology

Episodes of wheeze are often triggered by respiratory viruses. Although a viral throat swab is not necessary during the acute resuscitation, it is helpful for children requiring intravenous therapy to have a viral throat swab taken as soon as clinically able.

Safe transfer criteria

Patient should not be transferred between clinical areas until clinically stable or deemed appropriate by ED/Gen Paeds/PICU consultant.