An experimental model for the measurement of inspired gas temperatures in ventilated neonates

Jardine, Luke; Dunster, Kimble; Davies, Mark W

doi:10.1002/ppul.20731

Cited by 9 publications

(7 citation statements)

References 12 publications

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“…Recently, it has been reported, in an experimental neonatal lung model, that the inspired gas temperature drops in the exposed part of the ETT and the subsequent temperature elevation in the simulated air way and lungs. 15 This demonstration is similar to our present data. Additionally, they speculated that it may well be worth setting the temperature at the circuit temperature probe site even higher (i.e., >408C) to compensate for the drop in the exposed part of the ETT.…”

Section: Discussionsupporting

confidence: 94%

A drop in gas temperature in the external part of the endotracheal tube is problematic during neonatal respiratory support

Yamada

Kyuno

Suzuki

et al. 2008

Pediatric Pulmonology

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During neonatal respiratory support, maintaining optimal humidity minimizes the risk of airway occlusion and chronic lung disease. With neonatal respiratory support using a heated humidifier,condensation following decreases in temperature within the unheated part of the inspiratory circuit represents a serious problem, due to the resulting drop in absolute humidity. Several reports describing the temperature/humidity gradient in the unheated inspiratory limb have excluded the endotracheal tube (ETT). The present study investigated the extent to which the temperature gradient in the ETT affects breathing gas conditioning in premature infants, who display tiny minute volumes. By measuring temperature/dew point at various sites along the inspiratory circuit, including inside the ETT, we evaluated the effects of temperature change in the ETT using an in vitro model of a micropremie on mechanical respirator care in an incubator. We confirmed significant moisture loss (absolute humidity loss; 7.5-10.1 mg/L) with decreasing gas temperature in the ETT external to the body, with subsequent drying of the gas (relative humidity drop, 10.7-22.3%) as temperature increased in the ETT inside the body. The present results suggest that temperature decreases in the ETT represent an important issue in the respiratory care of very premature infants.

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Section: Discussionsupporting

confidence: 94%

A drop in gas temperature in the external part of the endotracheal tube is problematic during neonatal respiratory support

Yamada

Kyuno

Suzuki

et al. 2008

Pediatric Pulmonology

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“…In studies that used a model lung attached to the ventilator circuit, the results were found to be approximately the same. The mean inspired gas temperatures at the airway opening reaching the model lung were shown to be around ambient or incubator temperature 1,2,10,22,25,26. This result is important for nursing care, because incubator temperatures can be decreased in NICUs, based on the status or the postnatal age of preterm infants who no longer need a higher incubator temperature 27.…”

Section: Discussionmentioning

confidence: 91%

“…In view of this recommendation, humidifier devices are adjusted to 37°C in NICUs. However, recent studies have shown that the set temperature in humidifiers does not reach the airway of the preterm infant 1,2,5,6,20,22. It is therefore suggested that humidifier temperatures should be adjusted to 39°C to 40°C so that the target temperature for infants can be reached 1,5–7,10,11,22,23…”

Section: Discussionmentioning

confidence: 99%

“…However, recent studies have shown that the set temperature in humidifiers does not reach the airway of the preterm infant. 1,2,5,6,20,22 It is therefore suggested that humidifier temperatures should be adjusted to 39°C to 40°C so that the target temperature for infants can be reached. 1,[5][6][7]10,11,22,23 As far as we know, our study is the first to measure inspired air temperature and humidity for preterm neonates.…”

Section: Discussionmentioning

confidence: 99%

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The Effect of 2 Humidifier Temperature Settings on Inspired Gas Temperatures and the Physiological Parameters of Preterm Infants Receiving Mechanical Ventilation Therapy

Bayraktar¹,

Balcı

İnce

2020

Advances in Neonatal Care

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Background: The use of heated and humidified gas during mechanical ventilation is routine care in neonatal intensive care units. Giving gas at inadequate heat and humidity levels can affect neonatal morbidity and mortality. Purpose: To compare the effects of 2 humidifier temperature settings on the temperature and humidity of the inspired gas and the physiologic parameters in preterm newborns receiving mechanical ventilation. Methods: The research was conducted in a single-group quasi-experimental design. Proximal temperature was measured using a humidity heat transmitter. The humidifier temperature was set at 38°C (temperature I) and then at 39°C (temperature II). Results: The mean proximal temperatures were significantly lower than the values set in the humidifier (33.8 ± 1.20°C at temperature I, and 34.06 ± 1.30°C at temperature II, P < .001). However, the difference between the 2 proximal temperatures was not significant (P = .162). The incubator temperature was found to be effective on the proximal gas temperature (P < .05). It was found that only preterm infants in the temperature II group had a higher mean heart rate (P < .05). Implications for Practice: Incubator temperatures may have an effect on inspired gas temperature in preterm infants who are mechanically ventilated and caregivers should be aware of these potentially negative effects. Implications for Research: Future studies should focus on how to measure the temperature and humidity of gas reaching infants in order to prevent heat and humidity losses.

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“…It is important to note that both systems delivered mean temperatures to the patient connection that were 11°C below the target temperature. Jardine, et al [8] found that although there was a slight temperature drop from the set temperature of 40°C at the servo-controlled active heater, the target temperature of 37°C was attained at the proximal end of the endotracheal tube when the unheated portion of the ventilator circuit was removed. The 12-inch unheated section significantly reduces temperature delivery to the patient's artificial airway and subsequently lowers the absolute humidity [6].…”

Section: Discussionmentioning

confidence: 99%

An evaluation of temperature stability and resistance in neonatal ventilator circuits

Ruppert¹,

McNinch²,

Volsko³

2021

Can J Respir Ther

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Background: Gas conditioning minimizes complications associated with invasive ventilation of neonates. Poorly conditioned gas contributes to humidity deficit, facilitates condensate pools, and contributes to safety events. The specific aim was to objectively quantify the temperature drop across the unheated portion of a neonatal circuit and the impact condensation has to resistance to flow in the ventilator circuit. Methods: Ventilator circuits and filters were obtained, assembled according to manufacturer recommendations, and operational verification procedures were performed prior to data collection. A neonatal test lung was connected to each Servo-I ventilator with the following settings: pressure control IMV mode; inspiratory pressure: 14 cm H 2 O to achieve an exhaled tidal volume of 6.0 mL; PEEP: 5 cm H 2 O; pressure support: 5 cm H 2 O, F I O 2: 0.21; set frequency 40/min; and inspiratory time: 0.4 s. The Fisher and Paykel MR850 and ChonchaTherm Neptune heaters were set at a temperature of 40°C. To evaluate both systems under similar conditions, the ChonchaTherm Neptune heater humidity control was set to midline. Heaters were turned on simultaneously and given 1 h to equilibrate. Readings for room temperature, airway temperature at the patient connection, airway resistance, exhaled tidal volume, and direct observation of circuit condensation and (or) pooling were recorded hourly for a 48-h period. Summary statistics were calculated for the variables of interest. Results: Mean (±SD) air temperature was 26.3°C (±1.4) for the Fisher & Paykel MR850 system and 26.2°C (±1.5), for the ChonchaTherm Neptune system. Mean (±SD) airway resistance was 229.3 cm H 2 O/L/s (±81.0) for the Fisher & Paykel system and 196.2 cm H 2 O/L/s (±39.4) for the ChonchaTherm Neptune system. Mean (±SD) tidal volume for the Fisher & Paykel MR850 system was 6.5 mL (±0.4), and for the ChonchaTherm Neptune system was 7.2 mL (±0.6). Conclusion:Circuit condensate increased tidal volume delivery and airway resistance. Temperature at the patient connection was lower than the temperature monitored by the system 12 inches distally, which can negatively impact gas conditioning.

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An experimental model for the measurement of inspired gas temperatures in ventilated neonates

Cited by 9 publications

References 12 publications

A drop in gas temperature in the external part of the endotracheal tube is problematic during neonatal respiratory support

A drop in gas temperature in the external part of the endotracheal tube is problematic during neonatal respiratory support

The Effect of 2 Humidifier Temperature Settings on Inspired Gas Temperatures and the Physiological Parameters of Preterm Infants Receiving Mechanical Ventilation Therapy

An evaluation of temperature stability and resistance in neonatal ventilator circuits

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