A Comparative Study of the Effects of Dry Versus Humidified Ventilation on Canine Lungs

Fonkalsrud, Eric W.; Sánchez, MT Sánchez; Higashijima, I; Arima, Eitoku

doi:10.1097/00132586-197608000-00005

Cited by 8 publications

(13 citation statements)

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“…Bypassing the upper airways during mechanical ventilation has been shown to be detrimental to the pulmonary system if the inspired gases are not humidified effectively 1–4,7–11 . Over humidification of the inspired gases will also have a detrimental effect on this system 5,6,12,18–21 . Minimum inspired gas humidity standards have been set in the UK and USA, but there are no set upper limits 23,24…”

Section: Discussionmentioning

confidence: 99%

“…The water accumulation and decreased mucociliary clearance may provide a focus for infection 22 . Condensation in the inspiratory circuit of the ventilator has also been reported to increase the risk of accidental lavage in the neonate, 21 together with inactivation of surfactant and a decrease in compliance 19,20 . We have previously shown in rabbits ventilated for 6 h with particulate water reaching the lungs that there was an increase in interstitial thickness, intra alveolar oedema and the vascular wall thickness of the pulmonary arterioles, following the acute insult, and an increase in interstitial fibrosis 2 weeks later 5,6,12 .…”

Section: Discussionmentioning

confidence: 99%

“…Over humidification during ventilation is reported to a lesser extent but is nonetheless of great concern 18 . Damage may include thermal injury, hyperthermia, inactivation of surfactant and a decrease in compliance 19,20 . Condensation in the inspiratory circuit of the ventilator may increase the risk of accidental lavage in the neonate 21 and may provide a focus for infection 22 .…”

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confidence: 99%

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Inspired gas humidity during mechanical ventilation: Effects of humidification chamber, airway temperature probe position and environmental conditions

Todd

Boyd

Lloyd

et al. 2001

J Paediatrics Child Health

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Significant differences in inspired gas humidity were found with the humidification chambers tested. The position of the ATP and the set temperature had a significant impact on the absolute humidity of the inspired gas. In general, higher inspired gas humidities were obtained with the ATP outside the humidicrib. However, condensation of water close to the ETT appeared at low humidicrib temperatures (< 36.2 degrees C) with the ATP outside the humidicrib and extreme care should be taken that particulate water does not enter the lungs under these conditions.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

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Inspired gas humidity during mechanical ventilation: Effects of humidification chamber, airway temperature probe position and environmental conditions

Todd

Boyd

Lloyd

et al. 2001

J Paediatrics Child Health

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“…The clinical implication from this is that a patient, whose trachea is intubated, inhaling a gas at a high temperature and low relative humidity is at risk of producing a more viscous mucus while a patient inhaling a gas with a low temperature and high relative humidity is at risk for a more peripheral isothermic saturation boundary. A peripheral saturation boundary may cause impaired pulmonary function [2,9,10] resulting in hypoxaemia as a result of atelectasis and increased intrapulmonary shunting. Given that an absolute humidity > 20 mg.l -1 is recommended, it is therefore better that the inspired gas has a high relative humidity rather than a high temperature in order to reduce the risk of dehydration and increased mucus viscosity.…”

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confidence: 99%

The effect of a heat and moisture exchanger on humidity in a low‐flow anaesthesia system

Henriksson

Sundling²,

Hellman³

1997

Anaesthesia

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The heat and humidity in a low‐flow breathing system was measured in order to study the inherent humidifying properties of the system at low fresh gas flows (< 1 and 2 l.min−1) and whether a heat and moisture exchanger could compensate for the loss of heat and humidification occurring at higher fresh gas flows (5 l.min−1) in these systems. Sixty patients were randomly divided into three groups (< 1, 2 and 5 l.min−1 fresh gas flows) with a heat and moisture exchanger and three groups without a heat and moisture exchanger in the breathing system. Thirty minutes after the start of anaesthesia a control measurement was performed, after which a heat and moisture exchanger was inserted into the breathing system of the three groups randomly allocated to have one. Three more measurements were performed at 10, 30 and 60 min after control. At low fresh gas flows the humidifying properties of the low‐flow breathing system are adequate (i.e. provide an absolute humidity > 20 mg.l−1) but at a fresh gas flow of 5 l.min−1 there is a need for a heat and moisture exchanger for adequate humidification of the inspired gas.

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“…Consequences resulting from inadequate humidification of inspired gases have been described in numerous investigations over the past three decades [1][2][3][4][5][6] . Deleterious findings include morphologic damage to the tracheobronchial epithelium [3][4] , retardation of the mucociliary escalator 5 and heat loss 6 .…”

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confidence: 99%

Anaesthesia Circuits, Humidity Output, and Mucociliary Structure and Function

Branson

Campbell

Davis

et al. 1998

Anaesth Intensive Care

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We compared the effects of humidity delivered by the circle system at low fresh gas flows (FGF) with a conventional two-limb and coaxial circuit on the structure and function of the tracheobronchial epithelium in dogs. Animals were anaesthetized and mechanically ventilated using an anaesthesia ventilator to maintain normocarbia. Group I (control) animals received a FGF equal to the required minute ventilation mimicking an open circuit technique. Group II and III animals had FGF set at 20% of the required minute ventilation. Group II used a two-limb circuit and Group III used a coaxial circuit. Relative humidity and temperature of inspired gases were measured at baseline and hourly afterwards. In the first experiment, biopsies of the tracheobronchial tree were obtained bronchoscopically at baseline and then hourly for six hours. Microscopic examination of these samples allowed calculation of mean ciliary length. In the second experiment, tracheal mucus flow velocity (TMFV) was measured at baseline and hourly afterward, using a cinebroncho-fibrescopic method. Delivered absolute humidity was greatest with low FGF and the coaxial circuit, followed by low FGF and a conventional circuit, and high FGF (15±1.4 vs 9±0.8 vs 5±0.4 mg H 2 O, P<0.01) after two hours. Mean cilia length (µm) and TMFV (mm/min) fell during the first hour in all three groups. At hour two TMFV returned to baseline in Group III and was significantly greater than Groups I and II (0.8±0.4 vs 8.6±1.1 vs 15.4±2.1, P<0.001). Mean ciliary length demonstrated a similar pattern with reductions from baseline in all three groups for the first two hours. Groups II and III had an increase in cilia length beginning at hour three and were both significantly greater than Group I at hours 3 through 6 (1.3±0.5 vs 3.2±1.1 vs 4.2±0.8, P <0.001). Alterations in tracheobronchial structure and function result from exposure to dry gases and are amplified by the duration of exposure. Our findings suggest a minimum of 12 to 15 mg H 2 O/l is necessary to prevent these alterations. In this study, the combination of low FGF and a coaxial anaesthesia circuit reached this minimum threshold more quickly than a conventional two-limb circuit.

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A Comparative Study of the Effects of Dry Versus Humidified Ventilation on Canine Lungs

Cited by 8 publications

References 0 publications

Inspired gas humidity during mechanical ventilation: Effects of humidification chamber, airway temperature probe position and environmental conditions

Inspired gas humidity during mechanical ventilation: Effects of humidification chamber, airway temperature probe position and environmental conditions

The effect of a heat and moisture exchanger on humidity in a low‐flow anaesthesia system

Anaesthesia Circuits, Humidity Output, and Mucociliary Structure and Function

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