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Humidification

The normal function of the nose and upper airway is to warm, moisten and filter inspired air. The viscosity of secretions is partly dependant on the humidity of inspired air or gases. Patients with a tracheostomy tube in situ bypass normal  mechanisms and require adjuncts to facilitate humidification.  

  • Viscosity of secretions
  • Ability to cough and expectorate
  • Clinical status
  • Systemic hydration
  • compliancePatient
  • Method of humidification in use – if any of the above list remain a problem the current method of humidification may be inadequate.

If no additional humidification is supplied, damage may occur to cells in the respiratory tract. Secretions will be come more tenacious, reducing the ability to remove secretion either by suction or coughing. There is an increased risk of atelectasis, consolidation, pneumonia and blocking of the tracheostomy tube. To prevent this, humidification should be provided at all times. There are several ways of achieving this. Staff should take into consideration amount of secretions

Failure to provide adequate humidification and suction has resulted in narrowed inner lumen increasing respiratory workload. Distal tip of cuffed tube shown

Heat and Moisture Exchange (HMEF)

Buchanan Bib

  • Secretions are visible in the inner lumen.   Secretions inside the HME can increase the work of breathing and may create an obstruction
  • Filters are no longer intact
  • Routinely every 24 hours

 Replace if:

For patients who require low percentages of supplementary oxygen (≤28%) or who can maintain gas exchange on room air the addition of an HME to the tracheostomy tube will provide humidification. HMEs retain heat and moisture during expiration utilising this to warm and humidify the next inspired breath. They should be checked and replaced as required

Trachphone, Thermovent T (Swedish nose) and Tracheolife II heat and moisture exchangers, (HME).

Buchanan laryngectomy protector.

For patients who no longer require oxygen herapy, bibs work in a similar way to an HME  device. These should be changed on a daily basis.

Humidified Oxygen

Humidification circuits have a regulator to control the percentage of oxygen delivered to the patient. In order to ensure the correct percentage of oxygen is delivered, both the regulator on the humidifier and the oxygen flow meter must be correctly set. 

Water humidification works by bubbling oxygen through a reservoir of sterile water to allow dry medical gases to pick up water vapour.

Patients requiring oxygen therapy of greater than 28% should have oxygen delivered via a humidification device.  There are two ways this can be achieved, via tracheostomy masks, or via a T-Piece circuit. 

T-piece

Tracheostomy oxygen masks can be utilised for oxygen delivery in patients with uncuffed or cuff deflated tracheostomy tubes.  However, if used with a cuffed tube, staff should ensure cuff is deflated and the mask is rigid instead of flexible to avoid occlusion of the tracheostomy.

Tracheostomy oxygen mask with single lumen tracheostomy note cuff deflated

T-piece attachment supplying humidified oxygen

Patients breathing via cuff inflated tracheostomy tube will have humidified oxygen delivered via a T-Piece (Safety Action Notice 01/36/2001).  If a patient is unable to exhale the full length of the expired limb this will result in re-breathing of expired CO2. Likewise an overly short expired limb will result in a decreased oxygen delivery as the expiratory limb also acts as an oxygen reservoir for inspired gases.

The length of the expiratory limb of the T-Piece should be approximately 20 cms. A longer limb will increase the respiratory workload of the patient by increasing dead space resulting in retained CO2.

Nebulised normal saline can be used to improve humidification. This decreases the viscosity of secretions facilitating easier removal either by suction or allowing the patient to cough and expectorate. This is indicated in patients with tenacious  secretions that are difficult to remove or as a preventative measure for patients in addition to other humdification devices.

NB. Ensure that adequate oxygenation is maintained at all times. At no time should the breathing circuit be occluded.   Always ensure the tubing has an opening to the atmosphere.

Nebulised Saline

Close up of nebuliser circuit and nebuliser connection

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Please note excessive use of nebulised saline may increase the patients serum sodium levels. T-Piece oxygen with nebuliser connection