HUMIDITY THERAPY

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HUMIDITY THERAPY
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INTRODUCTION

• Humidity is water in its vapor form, and is
  invisible, referred to as molecular water
• Absolute humidity is the actual amount of water
  in a gas, expressed in mg/L
• Relative humidity is a ratio of actual water
  vapor present in a gas to the capacity it can
  hold at a given temp. (expressed in )

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Humidity (contd)

• Saturated gas is when th content of humidity
  present is equal to the capacity it can hold at a
  given temp. (100 R.H.)
• Dewpoint is the temp. at which water vapor
  condenses to a liquid
• Saturated air at body temp.(37C) contains 43.9
  mg/L and has a vapor pressure of 47 mmHg

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Humidity (contd)

• Humidity deficit exists when inspired gas
  contains lt43.9 mg/L (vapor press.lt47mmHg) and the
  mucosa has to expend water to bring the gas to
  full humidification
• Humidity of pathological degree can be produced
  by - breathing dry gas - mucosal
  crusting

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Clinical Humidity Therapy

• Clinical uses for molecular water (humidity) can
  be divided into two broad classes
• 1-- To humidify dry, therapeutic gases to make
  them more comfortable to breathe
• 2-- To provide near body humidity levels of
  inspired gases for patients with artificial
  airways

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Humidifying Therapeutic Gases

• Goal is to provide at least a level of humidity
  equal to or exceeding that in room air (hospitals
  have 30-70 R.H.)
• Do not add water to the airway, but prevents
  these gases from adding to the normal humidity
  deficit

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Providing Body Humidity

• Normally inspired air is warmed to nearly body
  temp. and is saturated with water vapor when it
  reaches the carina
• If upper airway is bypassed with an artificial
  airway, heated humidification system is used
• Heated humidifiers can provide saturated gas at
  or near body temp.
• H. H. do not add H2O to airway

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Manifestations of Humidity Deficit

• Reduced ciliary action leading to dry, hacking,
  NPC
• Inspissated secretions lead to increased airflow
  resist., increased level of infection, and
  atelectasis
• Earache d/t pressure on the eardrum
• Substernal pain d/t inflammation of airway tissue
  from contact with dry gas
• Sore throat d/t exposure to dry gas

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Manifest. of H.D.

• Dryness of skin leading to decreased skin turgor
• Unstable control of body fluids - normally
  takes 250 - 300 ml to humidify inspire
  air - pulmonary patient may lose 1000 - 2000
  ml leading to fluid imbalance and electrolyte
  imbalance

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Conditions Requiring Humidification

• Administration of medical gases from a cylinder
  or pipeline
• Environmental R.H. lt 40 in a patient without
  lung disease
• Environ. R.H. lt 70 in a patient with lung
  disease
• Patient with known secretions or a disease that
  causes secretions
• Anatomical humidifier is bypassed

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Contraindications for Humidity

• Situations leading to secretions swelling and
  blocking airway
• Situations where the patients body temp. may
  increase to undesirable levels

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Factors Relating to the Efficiency of any
Humidifier

• Surface area exposure between the water and the
  gas to be humidified
• Time the gas and H2O are in contact
• Temperature of both the water and the gas