Humidification Overview | Fisher & Paykel Healthcare

Humidification

Fisher & Paykel Healthcare cares for patients across the respiratory care continuum, including neonates, infants and children. We offer a comprehensive humidified respiratory solution for all therapies within that care continuum.

A newborn’s respiratory system is reliant on humidity to maintain physiological balance, assist natural defense mechanisms, and conserve energy for growth and development.

The benefits of delivering heated and humidified gases during all forms of respiratory support is well recognized from research ^1-4 and clinical practice.^5-6

• What is humidity?
• Three vital reasons why humidification is important

What is humidity?

Absolute Humidity (AH)

Absolute humidity (AH) represents the total amount of water vapor in a given volume of gas in which it is contained. AH is measured as mass divided by volume of gas (mg/L).

If the water held in a liter of gas was condensed and weighed in milligrams, the absolute humidity of the gas would be measured in milligrams per liter of gas.

Relative Humidity (RH)

Relative humidity (RH) takes in the water contained in the gas, compared with how much water it can hold before the vapor condenses to liquid water. RH is measured as a percentage.

100% RH: If the same volume of gas holds 44 mg of water vapor, it is full or saturated with water vapor, so its RH is 44 mg / 44 mg or 100% RH.

25% RH: If a liter of gas holds a maximum 44 mg of water vapor, it will be a quarter full and contain only 11 mg of water vapor, so its RH is 11 mg / 44 mg or 25% RH.

Temperature affects humidity

The quantity of water vapor that gas can hold increases with the temperature of the gas. A warm gas can hold more water vapor than a cold gas.³

Fig 3. Warm gas can hold more water vapor than cooler gas.

Particle size

Water vapor particles are too small to transport bacteria or viruses. Heated humidifiers generate water vapor.^7-12

Water vapor, viruses, bacteria and nebulized liquid water all have different particle sizes.

Fig 4. Relative sizing of common pathogens to water in both liquid and gas states. μm, micrometers (microns); 1 mm = 1,000 μm.

Three vital reasons why humidification is important

Invasive ventilation assist in defense mechanism

Assists the body’s natural defense mechanisms in the airway

The primary defense mechanism: Reflexes such as sneezing, coughing and gagging are supported by the natural filtration of nasal hairs and the upper airway. In preterm infants, these mechanisms can be underdeveloped.^13-15

Mucociliary transport – the second line of defense: The role of the mucociliary transport system is to trap inhaled contaminants (in mucus) and transport them up and out of the airway. The efficiency of this mechanism is reliant on several factors, including the temperature and humidity of inspired gas.^16,17

The lower the humidity of the inspired gas, the further it needs to travel down the airway before physiological temperature and humidity are reached.¹⁸

Promotes conservation of energy for growth and development

At birth, newborns are exposed to immediate cold stress and heat loss. Premature infants may also have limited heat production capabilities, along with an increased need to conserve limited energy reserves.¹⁹

Infants need energy for growth and development. Therefore, assisting in thermoregulation is important. There is a range of interventions such as ensuring a neutral thermal environment, drying towels and blankets, a radiant warmer, or skin-to-skin contact.

Humidifying delivered therapies is important also, to promote conservation of energy. When inadequate levels of humidity are inhaled, water vapor is drawn from the airway mucosa until the inspired gas has reached 37 °C, 44 mg/L H₂O. The energy cost to the infant for each gram of water removed from the mucosa is 0.58 cal (2.4 j).¹⁹

Supports patient comfort and therapy tolerance

In addition to assisting natural defense mechanisms in the airway and promoting conservation of energy for growth and development, adequate humidification during respiratory support has been found to increase patient comfort and therapy tolerance.^4,20-23

While this data is derived predominantly from adult patients, the principles are applicable to the pediatric population.^24-26 In particular, humidification is associated with the clearance of retained secretions and prevention of airway drying, which may subsequently improve lung compliance and the work of breathing.^27-29

Humidification Basics — Clinical Paper Summaries

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Humidification systems

F&P 850 Humidification System

The F&P 850™ System unites the delivery of heated humidification with clinical usability and the reduction of mobile circuit condensate. Clinically tested, clinically beneficial, clinically proven.

Airvo 2 High Flow System

An effective and versatile solution for delivering Optiflow nasal high flow. Larger-sized Optiflow™ Junior 2/2+ nasal interfaces can be combined with the Airvo™ 2 for a complete Optiflow system.

F&P 950 Humidification System

Enhanced usability. Minimized condensation. Advanced protection. The F&P 950™ is a premium performance humidification system that delivers many benefits to patients and healthcare providers.

Airvo 3 High Flow System

Provides compatibility with a wide range of Optiflow interfaces (down to Optiflow Junior 2 Medium), features an integrated battery for intra-hospital transport and offers both direct and low pressure oxygen-input methods.

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Explore and learn

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Greenspan J, Wolfson M, Shaffer T. Airway responsiveness to low inspired gas temperature in preterm neonates. J Pediatr. 1991, Mar, 118 (3), 443–445. View abstract.
Williams R, Rankin N, Smith T, Galler D, & Seakins P. Relationship between the humidity and temperature of inspired gas and the function of airway mucosa. Critical Care Medicine. 24, 1920–1929 (1996). View abstract.
Branson R, Gentile M. Is humidification always necessary during noninvasive ventilation in the hospital? Respir Care 2010, Feb, 55 (2) 209–216. View abstract.
ADHB. NW Newborn Clinical Guideline - Humidification. View abstract.
The Royal Children’s Hospital Melbourne. Clinical Guidelines (Nursing): Environmental humidity for premature neonates. View abstract.
American Association for Respiratory Care. Clinical Practice Guideline: Bland Aerosol Administration – 2003 Revision and Update. 2003, Respir Care 48, 529–533. View abstract.
Williams RB. The effects of excessive humidity. Respir Care Clin N Am, 1998, June, 4 (2), 215–228. View abstract.
Estes RJ, Meduri GU. The pathogenesis of ventilator-associated pneumonia: I. Mechanisms of bacterial transcolonization and airway inoculation. Intensive Care Medicine, 1995, April 21 (4), 365–383. View abstract.
Hamill R et al. An outbreak of Burkholderia (formerly Pseudomonas) cepacia respiratory tract colonization and infection associated with nebulized albuterol therapy. Ann Intern Med. 1995, May 15, 122 (10), 762–766. View abstract.
Saunders WB, 2012. Avery’s Diseases of the Newborn. View abstract.
Lindemann J, Leiacker R, Rettinger G, Keck T. Nasal mucosal temperature during respiration. Clin Otolaryngol Allied Sci. 2002, Jun, 27 (3), 135–139. View abstract.
Keck T, Leiacker R, Riechelmann H, Rettinger G. Temperature profile in the nasal cavity. Laryngoscope, 2000, Apr, 110 (4), pp 651-654. View abstract.
Mercke U. The influence of temperature on mucociliary activity. Temperature range 40 degrees C to 50 degrees C. Acta Otolaryngol. 1974, Sep-Oct, 78 (3-4), 253–258. View abstract.
Gotera C, Díaz Lobato S, Pinto T, Winck JC. Clinical evidence on high-flow oxygen therapy and active humidification in adults. Rev Port Pneumol. 2013, Sep-Oct, 19 (5), 217-227. View abstract.
Bustamante-Marin XM, Ostrowski LE. Cilia and mucociliary clearance. Cold Spring Harb Perspect. Biol, 2017, April 3, 9 (4). View abstract.
Primiano FJ et al. Water vapor and temperature dynamics in the upper airways of normal and CF subjects. Eur Respir J. 1998, May, 1 (5), 407–414. View abstract.
World Health Organization. Maternal Health and Safe Motherhood Unit. Thermal control of the newborn: a practical guide. Geneva, 1992, pp 1-37. View abstract.
Pollett HF & Reid WD. Prevention of obstruction of nasopharyngeal CPAP tubes by adequate humidification of inspired gases. Can Anaesth Soc J. 1977, Sep, 24 (5), 615-617. View abstract.
Tuggey JM, Delmastro M, Elliott MW. The effect of mouth leak and humidification during nasal non-invasive ventilation. Respir Med, 2007, Sep, 101 (9), 1874-1879. View abstract.
Massie, CA, Hart RW, Peralez K, Richards GN. Effects of humidification on nasal symptoms and compliance in sleep apnea patients using continuous positive airway pressure. Chest, 1999, Aug, 116 (2), 403–408. View abstract.
Wiest GH et al. A heated humidifier reduces upper airway dryness during continuous positive airway pressure therapy. Respir Med, 1999, Jan, 93 (1), 21–26. View abstract.
De Boeck K, Vermeulen F, Vreys M, Moens M, Proesmans M. Airway clearance techniques to treat acute respiratory disorders in previously healthy children: Where is the evidence? Eur J Pediatr. 2008, Jun, 167 (6), 607-612. View abstract.
Fink JB. Forced expiratory technique, directed cough, and autogenic drainage. Respir Care, 2007, Sep, 52 (9), 1210-122. View abstract.
Hess DR. The evidence for secretion clearance techniques. Respir Care, 2001, Nov, 46 (11), 1276-1293). View abstract.
Volsko TA. Airway clearance therapy: Finding the evidence. Respir Care, 2013, Oct 58 (10), 1669–1678. View abstract.
Morrow BM. Airway clearance therapy in acute paediatric respiratory illness: A state-of-the-art review. South African J Physiother, 2019, Jun. 75 (1). View abstract.
Plotnikow GA, Accoce M, Navarro E, Tiribelli N. Humidification and heating of inhaled gas in patients with artificial airway: A narrative review. Rev Bras Ter Intensiva, 2018, Mar 30 (1), 86–97. View abstract.

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