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The Effects of Gas Humidification with High-Flow Nasal Cannula on Cultured Human Airway Epithelial Cells
Aaron Chidekel,Yan Zhu,Jordan Wang,John J. Mosko,Elena Rodriguez,Thomas H. Shaffer
Pulmonary Medicine , 2012, DOI: 10.1155/2012/380686
Abstract: Humidification of inspired gas is important for patients receiving respiratory support. High-flow nasal cannula (HFNC) effectively provides temperature and humidity-controlled gas to the airway. We hypothesized that various levels of gas humidification would have differential effects on airway epithelial monolayers. Calu-3 monolayers were placed in environmental chambers at 37°C with relative humidity (RH) < 20% (dry), 69% (noninterventional comparator), and >90% (HFNC) for 4 and 8 hours with 10 L/min of room air. At 4 and 8 hours, cell viability and transepithelial resistance measurements were performed, apical surface fluid was collected and assayed for indices of cell inflammation and function, and cells were harvested for histology (=6/condition). Transepithelial resistance and cell viability decreased over time (<0.001) between HFNC and dry groups (<0.001). Total protein secretion increased at 8 hours in the dry group (<0.001). Secretion of interleukin (IL)-6 and IL-8 in the dry group was greater than the other groups at 8 hours (<0.001). Histological analysis showed increasing injury over time for the dry group. These data demonstrate that exposure to low humidity results in reduced epithelial cell function and increased inflammation.
Humidification Performance of Heat and Moisture Exchangers for Pediatric Use  [PDF]
Yusuke Chikata,Chihiro Sumida,Jun Oto,Hideaki Imanaka,Masaji Nishimura
Critical Care Research and Practice , 2012, DOI: 10.1155/2012/439267
Abstract: Background. While heat and moisture exchangers (HMEs) have been increasingly used for humidification during mechanical ventilation, the efficacy of pediatric HMEs has not yet been fully evaluated. Methods. We tested ten pediatric HMEs when mechanically ventilating a model lung at respiratory rates of 20 and 30?breaths/min and pressure control of 10, 15, and 20?cmH2O. The expiratory gas passed through a heated humidifier. We created two rates of leakage: 3.2?L/min (small) and 5.1?L/min (large) when pressure was 10?cmH2O. We measured absolute humidity (AH) at the Y-piece. Results. Without leakage, eight of ten HMEs maintained AH at more than 30?mg/L. With the small leak, AH decreased below 30?mg/L (26.6 to 29.5?mg/L), decreasing further (19.7 to 27.3?mg/L) with the large leak. Respiratory rate and pressure control level did not affect AH values. Conclusions. Pediatric HMEs provide adequate humidification performance when leakage is absent. 1. Introduction In spontaneous breathing subjects, inspiratory gases are heated and humidified in the nasal cavity and pharynx; by the time, they reach the second bronchial bifurcation, temperature reaches 37°C, and absolute humidity reaches (AH) 44?mg/L [1]. In mechanically ventilated patients, because artificial airways bypass this natural gas conditioning, administered gases require heating and humidification. Inadequate humidification induces inspissations of airway secretions, destruction of airway epithelium, and hypothermia [2]. The incidence of endotracheal tube occlusion was reported between 0.8% and 2.6% in pediatric patients [3, 4]. The American Association for Respiratory Care (AARC) recommends that inspiratory gases should reach a temperature of more than 30°C and AH of more than 30?mg/L [2]. Heat and moisture exchangers (HMEs) and heated humidifiers (active humidification) are commonly employed to warm and humidify medical gases. While HMEs are widely used during the mechanical ventilation of adults [5], their performance varies depending on model [6] and is affected by location, tidal volume, and minute volume [7, 8]. For pediatric patients, because HME adds significant dead space and airway resistance to the circuit, and because there is a high risk of inadequate humidification owing to leakage around the endotracheal tube (ETT), long-term use of HMEs is generally avoided. Few studies, however, have reported how ventilator settings and ETT leakage influence the humidification performance of HMEs used for pediatric patients. Using a pediatric model lung, we carried out a bench study to evaluate the
Clinical research progress of humidified high-flow nasal cannula therapy in pediatric patients

TONG Xing-yu
, YOU Sha-sha, CAO Hui-min, HE Bin

- , 2018, DOI: 10.3969/j.issn.1674-8115.2018.05.017
Abstract: 多种形式的无创呼吸支持可适用于婴儿呼吸窘迫和低氧血症的治疗。在新生儿重症监护病房最常见的是经鼻持续气道正压通气(nasal continuous positive airway pressure, NCPAP),但新生儿不易耐受,有继发黏膜损伤和院内感染的风险。近些年来,湿化高流量鼻导管通气(humidified high-flow nasal cannula, HHFNC)治疗已经被引入,因其增加了患儿的舒适度和耐受性同时保证通气的有效性,正逐渐成为替代 NCPAP的另一种无创呼吸支持模式。该文将对近些年 HHFNC治疗儿科患者的研究进展进行综述。
:Various forms of noninvasive respiratory support have been applied to the treatment of infant respiratory distress and hypoxemia. The most common noninvasive respiratory support in neonatal intensive care unit is nasal continuous positive airway pressure (NCPAP). But the NCPAP systems are not always well acceptedthe neonatal population, with the risk of mucosal injury and nosocomial infection. In recent years, humidified high-flow nasal cannula (HHFNC) has been introduced and developed as a possible alternative to NCPAP for noninvasive respiratory support mode, becait increases patients’ comfort and the effectiveness of the ventilation. This article summarized the current research progress of HHFNC therapy in pediatric patients
Humidification in intensive care
T Williams
Southern African Journal of Critical Care , 2005,
Abstract: Humidification of inspired gases is an essential part of modern intensive care practice, but there is wide international variation in the application of humidification devices.1 This review aims to briefly cover the reasons why humidification is important and the main methods of humidification used, outlining their different strengths and weaknesses. SAJCC Vol. 21 (1) 2005: pp. 26-31
Humidification for intubated patients  [PDF]
Aphrodite Tsavourelou,Fotoula Babatsikou
To Vima tou Asklipiou , 2008,
Abstract: Artificial airways bypass the physiological mechanism of humidification and filtration of the inspired air, increasing, therefore, the possibilities of copious secretions production. Copious secretions increase the danger for atelektasis and respiratory infections. Moreover, clots can be shaped in the interior of the endotracheal tube or thracheostomy, resulting in increased work of breathing (WOB) and reduced odds of successful extubation. It is also possible to lead progressively to complete obstruction of the endotracheal tube.Thus, the choice of a suitable humidification device during mechanical ventilation is of distinguished importance. There are various types of humidifiers. However, hydroscopic Heat and Moisture Exchangers (HMEs) with filter and Heated Humidifiers (HHs), which provide humidity in form of water vapors, are currently used. When they are used correctly, and not in the cases where they are contraindicated, HMEs’ do not have complications and they decrease the cost of hospitalization as well as the staff workload. HMEs are better choice for short duration of intubation (<96 hours) and during transports. HHs are preferred for patients with persisting hypercapnia, chronic respiratory failure and difficulty in ventilator weaning. HHs should be used for patients with prolonged duration of mechanical ventilation or patients that HMEs are contraindicated for. Neither HMEs nor HHs have been accused for increased incidences of ventilator associated pneumonia (VAP).
Encuesta sobre humidificación de la vía aérea en unidades de cuidados intensivos de adultos de Chile Airway humidification practices in Chilean intensive care units
Jaime Retamal,Juan Castillo,Guillermo Bugedo,Alejandro Bruhn
Revista médica de Chile , 2012,
Abstract: Background: In patients with an artificial airway, inspired gases can be humidified and heated using a passive (heat and moisture exchange filter - HMEF), or an active system (heated humidifier). Aim: To assess how humidification is carried out and what is the usual clinical practice in this field in Chilean intensive care units (ICUs). Material and Methods: A specific survey to evaluate humidification system features as well as caregivers' preferences regarding humidification systems, was carried out on the same day in all Chilean ICUs. Results: Fifty-five ICUs were contacted and 44 of them completed the survey. From a total of 367 patients, 254 (69%) required humidification because they were breathing through an artificial airway. A heated humidifier was employed only in 12 patients (5%). Forty-three ICUs (98%) used HMEF as their routine humidification system. In 52% of surveyed ICUs, heated humidifiers were not available. Conclusions: In Chile the main method to humidify and heat inspired gases in patients with an artificial airway is the HMEF. Although there are clear indications for the use of heated humidifiers, they are seldom employed.
A new device for 100 per cent humidification of inspired air
Anders Larsson, Ann Gustafsson, Lennart Svanborg
Critical Care , 2000, DOI: 10.1186/cc651
Abstract: To test the performance of the new humidifier at different ventilator settings in a lung model, and to compare this new humidifier with a conventional active humidifier in ventilator-treated critically ill patients.The humidifier (Humid-Heat; Louis Gibeck AB, Upplands V?sby, Sweden) consists of a supply unit with a microprocessor and a water pump, and a humidification device, which is placed between the Y-piece and the endotracheal tube. The humidification device is based on a hygroscopic heat-moisture exchanger (HME), which absorbs the expired heat and moisture and releases it into the inspired gas. External heat and water are then added to the patient side of the HME, so the inspired gas should reach 100% humidity at 37°C (44 mg H2O/l air). The external water is delivered to the humidification device via a pump onto a wick and then evaporated into the inspired air by an electrical heater. The microprocessor controls the water pump and the heater by an algorithm using the minute ventilation (which is fed into the microprocessor) and the airway temperature measured by a sensor mounted in the flex-tube on the patient side of the humidification device.The performance characteristics were tested in a lung model ventilated with a constant flow (inspiratory:expiratory ratio 1:2, rate 12–20 breaths/min and a minute ventilation of 3–25 l/min) or with a decelerating flow (inspiratory:expiratory ratio 1:2, rate 12–15 breaths/min and a minute ventilation of 4.7–16.4 l/min). The device was also tested prospectively and in a randomized order compared with a conventional active humidifier (Fisher & Paykel MR730, Auckland, New Zealand) in eight mechanically ventilated, endotracheally intubated patients in the intensive care unit. The test period with each device was 24 h. The amount of fluid consumed and the amount of water in the water traps were measured. The number of times that the water traps were emptied, changes of machine filters, the suctions and quality of secretions, n
A new prototype of an electronic jet-ventilator and its humidification system
Paul Kraincuk, Anton Kepka, Gerald Ihra, Christa Schabernig, Alexander Aloy
Critical Care , 1999, DOI: 10.1186/cc351
Abstract: To assess a prototype of an electronic jet-ventilator and its humidification system.Forty patients with respiratory insufficiency were randomly allocated to one of four groups. The criterion for inclusion in this study was respiratory insufficiency exhibiting a Murray score above 2. The four groups of patients were ventilated with three different respirators and four different humidification systems. Patients in groups A and B received superimposed high-frequency jet ventilation (SHFJV) by an electronic jet-ventilator either with (group A) or without (group B) an additional humidification system. Patients in group C received high-frequency percussive ventilation (HFPV) by a pneumatic high-frequency respirator, using a hot water humidifier for warming and moistening the inspiration gas. Patients in group D received conventional mechanical ventilation using a standard intensive care unit respirator with a standard humidification system. SHFJV and HFPV were used for a period of 100 h (4days).A significantly low inspiration gas temperature was noted in patients in group B, initially (27.2 ± 2.5°C) and after 2 days (28.0 ± 1.6°C) (P < 0.05). The percentage of relative humidity of the inspiration gas in patients in group B was also initially significantly low (69.8 ± 4.1%; P < 0.05) but rose to an average of 98 ± 2.8% after 2 h. The average percentage across all four groups amounted to 98 ± 0.4% after 2 h. Inflammation of the tracheal mucosa was found in patients in group B and the mucosal injury score (MIS) was significantly higher than in all the other groups. Patients in groups A, C and D showed no severe evidence of airway damage, exhibiting adequate values of relative humidity and temperature of the inspired gas.The problems of humidification associated with jet ventilation can be fully prevented by using this new jet-ventilator. These data were sustained by nondeteriorating MIS values at the end of the 4-day study period in groups A, C and D.High-frequency jet venti
Effect of heat and moisture exchanger (HME) positioning on inspiratory gas humidification
Daisuke Inui, Jun Oto, Masaji Nishimura
BMC Pulmonary Medicine , 2006, DOI: 10.1186/1471-2466-6-19
Abstract: Absolute humidity (AH) and temperature (TEMP) at the proximal end of endotracheal tube (ETT) were measured in ten mechanically ventilated patients. The HME was connected either directly proximal to the ETT (Site 1) or at before the circuit Y-piece (Site 2: distance from proximal end of ETT and Site 2 was about 19 cm) (Figure. 1). Two devices, Hygrobac S (Mallinckrodt Dar, Mirandola, Italy) and Thermovent HEPA (Smiths Medical International Ltd., Kent, UK) were tested. AH and TEMP were measured with a hygrometer (Moiscope, MERA Co., Ltd., Tokyo, Japan).Hygrobac S provided significantly higher AH and TEMP at both sites than Thermovent HEPA. Both Hygrobac S and with Thermovent HEPA provided significantly higher AH and TEMP when placed proximally to the ETT.Although placement proximal to the ETT improved both AH and TEMP in both HMEs tested, one HME performed better in the distal position than the other HME in the proximal position. We conclude the both the type and placement of HME can make a significant difference in maintaining AH and TEMP during adult ventilation.During normal breathing, the upper airway effectively deliver inspired air to the lower respiratory tract (at the carina) condition to approximately 32°C with a relative humidity (RH) of more than 90% (absolute humidity (AH) 30.4 mg/L)[1]. As this inspired air enters the alveoli, it is warmed to body temperature (about 37°C) and reaches 100% humidification [2,3]. When the upper airways are circumvented, delivery of dry gas to the lungs has been associated with damage to the tracheobronchial mucosa [4-7]. Consequently, when the natural humidification of the upper airways is bypassed by an endotracheal or tracheostomy tube, artificial humidification of inspiratory gas is essential for mechanically ventilated patients. As an alternative to heated humidifiers, heat and moisture exchangers (HME) have been widely adopted in intensive care units (ICU) [8]. HME performance is influenced by many factors, including mo
A new adjunctive system to obtain higher PaO2 with nasal cannula or catheter: double trunk mask
G Bodur, F Duprez, A Laghmiche, E Gatera
Critical Care , 2001, DOI: 10.1186/cc1072
Abstract: To demonstrate how a simple adjunctive system to classical nasal cannula or catheter improves considerably the oxygenation of patients at constant O2 flow rate.Prospective, observational study.The double trunk mask (DTM) is a modified tusk mask described by Hnatiuk. It is composed by a normal aerosol mask with 22 mm of diameter lateral holes, 38 cm of long flexible tubing are inserted to each side of the mask. The DTM is just applied to the face of the patients who already receive O2 through a nasal cannula or catheter. Forty-five consecutive patients, admitted in the ER or ICU, and needing oxygen delivery, are included in our study. The data collected are: PaO2, PaCO2, breathing rate with a mean flow rate of 3.58 l/min, at t0, t30 min prior to DTM and then 30 min after DTM application.In patients who remain insufficiently oxygenated although receiving O2 with classical nasal cannula or catheter, the DTM is a new, simple and efficient system to obtain high PaO2 at the same O2 flow rate and without significant change in PaCO2.
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