THE EFFECTS OF INSPIRATION OF GASES SATURATED WITH WATER VAPOUR ON HEAT AND MOISTURE EXCHANGE DURING ENDOTRACHEAL INTUBATION

In recent decades, Heat and Moisture Exchange (HME) devices have been employed increasingly for short-term use in anaesthesia and long-term use in intensive care units. These devices work as heat exchangers, accumulating the patient’s expired heat and moisture and returning them to the patient during the inhalation phase. Porous matrices obtained from freeze-drying of blends of natural polymers exhibit high open and interconnected porosity and water vapour intake characteristics which make them possible candidates for HME devices. Preliminary tests were conducted on specimens made of gelatine blended with chitosan and treated with a non-toxic cross-linking agent. The tests were carried out in cyclic flow conditions with saturated and dried air. Results show water vapour retention comparable with accepted standards for HME devices.

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A Reappraisal of the Multiple Gauze Heat and Moisture Exchanger

Anaesthesia and Intensive Care ◽

10.1177/0310057x7300100511 ◽

1973 ◽

Vol 1 (5) ◽

pp. 428-432 ◽

Cited By ~ 1

Author(s):

C. A. Shanks ◽

C., A. Sara

Keyword(s):

Water Vapour ◽

Considerable Increase ◽

High Water ◽

Heat And Moisture Exchanger ◽

Water Vapour Content ◽

Moisture Exchanger ◽

Moisture Exchange ◽

Controlled Ventilation ◽

Heat And Moisture

The multiple gauze heat and moisture exchanger was assessed under standardized conditions, at five levels of predetermined fresh gas humidity. As predicted theoretically, the unit functioned best when presented with fresh gases with high water vapour content. The ordinary unit moistened arid gases during inspiration to a level unacceptable for prolonged use. Unheated simple humidification systems dampen anhydrous stored gases and combined with the standard condenser-humidifier produce a microclimate suitable for entry into the trachea during spontaneous or controlled ventilation. Quadrupling the number of gauzes improved heat and moisture exchange with all but the saturated fresh gases. However, there was a considerable increase in weight.

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Airway Heat and Humidity during Endotracheal Intubation—4: Connotations of Delivered Water Vapour Content

Anaesthesia and Intensive Care ◽

10.1177/0310057x7400200303 ◽

1974 ◽

Vol 2 (3) ◽

pp. 212-220 ◽

Cited By ~ 3

Author(s):

C. A. Shanks ◽

C. A. Sara

Keyword(s):

Moisture Content ◽

Water Vapour ◽

Endotracheal Intubation ◽

Heat Balance ◽

Mouth Breathing ◽

Whole Body ◽

Tracheal Mucosa ◽

Water Vapour Content ◽

Heat And Moisture ◽

Body Heat

The measurement of airway humidity is reviewed, particularly the methods which have been used during anaesthesia and endotracheal intubation. Reported heat and moisture patterns are related to possible effects on the tracheal mucosa and whole body heat balance. Mucosal dysfunction and hypothermia are more likely when dry gases are inhaled from a non-rebreathing system. Even with high fresh-gas inflow, the circle absorber system appears to present an inspiratory moisture content which is comparable to that found during mouth breathing.

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Airway Heat and Humidity during Endotracheal Intubation: I. Inspiration of Arid Gases via a Non-Rebreathing Circuit

Anaesthesia and Intensive Care ◽

10.1177/0310057x7300100303 ◽

1973 ◽

Vol 1 (3) ◽

pp. 211-214 ◽

Cited By ~ 8

Author(s):

Colin Shanks ◽

Charles Sara

Keyword(s):

Respiratory Tract ◽

General Anaesthesia ◽

Endotracheal Intubation ◽

Major Part ◽

Clinical Results ◽

Moisture Exchange ◽

Model Lung ◽

Heat And Moisture

Investigation into the patterns of respiratory heat and moisture exchange in intubated patients, under general anaesthesia, is detailed. This paper gives the inspiratory and expiratory temperatures and humidities found in a non-rebreathing circuit near the valve and near the trachea. A model lung was constructed to control and determine factors which have been implicated in playing a major part in heat and moisture homeostasis within the respiratory tract. Laboratory and clinical results are compared.

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Airway Heat and Humidity during Endotracheal Intubation: III. Rebreathing from the Circle Absorber System at Low Fresh Gas Flow

Anaesthesia and Intensive Care ◽

10.1177/0310057x7300100508 ◽

1973 ◽

Vol 1 (5) ◽

pp. 415-417 ◽

Cited By ~ 2

Author(s):

C. A. Shanks ◽

C. A. Sara

Keyword(s):

Endotracheal Intubation ◽

Gas Flow ◽

Room Temperature ◽

Moisture Uptake ◽

Moisture Exchange ◽

Heat And Moisture ◽

Circle Absorber

Gas temperatures and humidities were examined when the fresh gas flow into a circle absorber system was one 1/minute. The environment cooled gases in the circuit to a minimum at the patient end of the inspiratory tubing; here the saturated gas was 2°C above room temperature. Moisture uptake kept pace with temperature gain during inspiration and relative humidities remained high. Under these conditions, heat and moisture exchange in the artificial airways produced end-inspired temperatures and humidities in the gases entering the trachea which were close to normal subglottic values.

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