OPTIMUM HUMIDIFICATION OF AIR ADMINISTERED TO A TRACHEOSTOMY IN DOGS: Scanning electron microscopy and surfactant studies

Tsuda, Toshitaka; Noguchi, Hiroshi; Takumi, Y; Aochi, O

doi:10.1093/bja/49.10.965

Cited by 85 publications

(32 citation statements)

References 20 publications

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“…Clinicians should be cautious as there is limited clinical experience with such conditions of humidification, which could lead to increased secretions and micro-atelectasis, as has been described in animals. 34,35 In conclusion, the humidification performance of passive, performing, hygroscopic and hydrophobic HMEs, and of active HMEs is not influenced by minute ventilation in the conditions tested in the present study, and ambient temperature has only a negligible influence. These systems are stable over a range of tested external conditions, and there is no reason to avoid their use in the case of high ambient temperature or in the case of high minute ventilation.…”

Section: Discussionmentioning

confidence: 45%

Influence of Ambient Temperature and Minute Ventilation on Passive and Active Heat and Moisture Exchangers

et al. 2013

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OBJECTIVE: During invasive mechanical ventilation, inspired gases must be humidified. We previously showed that high ambient temperature greatly impaired the hygrometric performance of heated wire-heated humidifiers. The aim of this bench and clinical study was to assess the humidification performance of passive and active heat and moisture exchangers (HMEs) and the impact of ambient temperature and ventilator settings. METHODS: We first tested on the bench a device with passive and active humidification properties (Humid-Heat, Teleflex), and 2 passive hydrophobic/hygroscopic HMEs (Hygrobac and Hygrobac S, Tyco Healthcare). The devices were tested at 3 different ambient temperatures (from 22 to 30°C), and at 2 minute ventilation settings (10 and 20 L/min). Inspired gas hygrometry was measured at the Y-piece with the psychrometric method. In addition to the bench study, we measured the hygrometry of inspired gases in 2 different clinical studies. In 15 mechanically ventilated patients, we evaluated Humid-Heat at different settings. Additionally, we evaluated Humid-Heat and compared it with Hygrobac in a crossover study in 10 patients. RESULTS: On the bench, with the Hygrobac and Hygrobac S the inspired absolute humidity was ϳ30 mg H 2 O/L, and with the Humid-Heat, slightly < 35 mg H 2 O/L. Ambient temperature and minute ventilation did not have a clinically important difference on the performance of the tested devices. During the clinical evaluation, Humid-Heat provided inspired humidity in a range from 28.5 to 42.0 mg H 2 O/L, depending on settings, and was only weakly influenced by the patient's body temperature. CONCLUSIONS: In this study both passive and active HMEs had stable humidification performance with negligible influence of ambient temperature and minute ventilation. This contrasts with previous findings with heated wire-heated humidifiers. Although there are no clear data demonstrating that higher humidification impacts outcomes, it is worth noting that humidity was significantly higher with the active HME.

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Section: Discussionmentioning

confidence: 45%

Influence of Ambient Temperature and Minute Ventilation on Passive and Active Heat and Moisture Exchangers

et al. 2013

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“…However, subjects who received humidification therapy during mechanical ventilation did not present with any significant changes to their epithelial cell structure. Previous studies 29,30 showed that, during general anesthesia, the delivery of cold, dry gas into the lower respiratory tract resulted in pulmonary surfactant changes, increased pulmonary surface tension, and alveolar collapse. Based on the data presented in this report, we recommend that patients receiving general anesthesia also receive humidification therapy.…”

Section: Discussionmentioning

confidence: 99%

Airway Humidification Reduces the Inflammatory Response During Mechanical Ventilation

et al. 2015

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BACKGROUND: Currently, no clinical or animal studies have been performed to establish the relationship between airway humidification and mechanical ventilation-induced lung inflammatory responses. Therefore, an animal model was established to better define this relationship. METHODS: Rabbits (n ‫؍‬ 40) were randomly divided into 6 groups: control animals, sacrificed immediately after anesthesia (n ‫؍‬ 2); dry gas group animals, subjected to mechanical ventilation for 8 h without humidification (n ‫؍‬ 6); and experimental animals, subjected to mechanical ventilation for 8 h under humidification at 30, 35, 40, and 45°C, respectively (n ‫؍‬ 8). Inflammatory cytokines in the bronchi alveolar lavage fluid (BALF) were measured. The integrity of the airway cilia and the tracheal epithelium was examined by scanning and transmission electron microscopy, respectively. Peripheral blood white blood cell counts and the wet to dry ratio and lung pathology were determined. RESULTS: Dry gas group animals showed increased tumor necrosis factor alpha levels in BALF compared with control animals (P < .05). The tumor necrosis factor alpha and interleukin-8 levels in the BALF reached baseline levels when the humidification temperature was increased to 40°C. Scanning and transmission electron microscopy analysis revealed that cilia integrity was maintained in the 40°C groups. Peripheral white blood cell counts were not different among those groups. Compared with control animals, the wet to dry ratio was significantly elevated in the dry gas group (P < .05). Moreover, humidification at 40°C resulted in reduced pathologic injury compared with the other groups based on the histologic score. CONCLUSIONS: Pathology and reduced inflammation observed in animals treated at 40°C was similar to that observed in the control animals, suggesting that appropriate humidification reduced inflammatory responses elicited as a consequence of mechanical ventilation, in addition to reducing damage to the cilia and reducing water loss in the airway.

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“…Os autores observaram que o sistema respirató-rio sem absorvedor e com alto fluxo de gases frescos mostrou valores significativamente menores da umidade relativa (entre 37% a 39%) e absoluta (entre 8 a 9 mg H 2 O.L -1 ) do que o grupo com baixo fluxo e absorvedor de CO 2 , quando a umidade relativa ficou ao redor de 75% a 79% e a umidade abso- , mas, em nossa opinião, o menor limite de umidificação durante a anestesia é difícil de determinar 1 , porque ele depende da duração da anestesia, das condições pulmonares prévias do paciente e do sistema respiratório empregado. Os estudos referentes à umidificação foram feitos especialmente em animais de laboratório 8, [32][33][34][35] . Investigações no homem são limitadas pelo pequeno número de pacientes envolvidos em cada pesquisa e a ausência de informações sobre os pacientes envolvidos em cada estudo 2,17 .…”

Section: Discussionunclassified

“…, but, in our opinion, it is difficult to determine the lowest humidification limit during anesthesia 1 because it depends on anesthesia duration, previous pulmonary conditions and the respiratory system used. Humidification studies were primarily performed with animals 8, [32][33][34][35] . In men, investigations are limited by the small number of patients involved and the lack of information about patients involved in each study 2,17 .…”

Section: Discussionmentioning

confidence: 99%

Umidificação e aquecimento do gás inalado durante ventilação artificial com baixo fluxo e fluxo mínimo de gases frescos

Gorayb¹,

Bráz²,

Martins³

et al. 2004

Rev. Bras. Anestesiol.

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RESUMO B A C K G R O U N D A N D O B J E C T I V E S : I n h a l e d g a s humidification and heating are necessary in patients under tracheal intubation or tracheostomy to prevent damage to respiratory system resulting from the contact of cold and dry gas with the airways. This study aimed at evaluating the effect of respiratory circle systems with carbon dioxide absorbers from Dräger's Cicero anesthesia machine (Germany) as to inhaled gases heating and humidification ability using low fresh gases flow (1 L.minoxygen only. Evaluated attributes were temperature, relative and absolute humidity of the operating room and of respiratory circuit gas. RESULTS: There were no significant differences in inhaled gas temperature, relative and absolute humidity between groups, but they have increased along time in both groups, with influence of operating room temperature on inhaled gas temperature for both groups. Near optimal levels of humidity and temperature were reached as from 90 minutes in both groups. CONCLUSIONS: There have been no significant differences in inhaled gas humidity and temperature with fresh gases low flow or minimum flow. , com surgimento de atelectasias e complicações pulmonares 3 . Assim, durante a ventilação artificial realizada sob intubação traqueal, o aquecimento e a umidificação dos gases inspirados são essenciais para assegurar a integridade das vias aé-reas, preservação da função mucociliar e melhora das trocas gasosas 4 . A umidade pode ser conceituada de várias formas: umidade máxima, que é a quantidade máxima de vapor de água que pode existir na fase gasosa de uma determinada atmosfera, na dependência de sua temperatura; umidade absoluta, que é a massa de vapor de água presente em determinado volume de gás, sendo usualmente expressa em mg de água por litro de gás; e umidade relativa representada pela relação entre a massa de vapor de água contida em um determinado volume de gás à determinada temperatura e a massa de vapor de água máxima que esse volume de gás poderia conter à mesma temperatura. Para facilitação dos cálculos de umidade existem tabelas propostas para cálculo de umidade absoluta em função da temperatura 5 . Ainda não se tem completa concordância em relação aos ní-veis ideais de aquecimento e umidificação dos gases inalados pelos pacientes, mas torna-se necessário o estabelecimento de limites de aquecimento e umidificação do gás inspirado 6,7 . Teoricamente, a temperatura do gás deve estar pró-xima à da temperatura central, que é de 37 ºC, e a umidade relativa não deve ultrapassar 100%, para que não ocorra desidratação da mucosa da árvore respiratória e a velocidade do transporte mucociliar seja máxima 3 . Entre nós, verificou-se, em estudo experimental em cães submetidos à intubação traqueal e ventilação mecânica durante três horas, os efeitos do aquecimento e umidificação absoluta dos gases inspirados, de acordo com as alterações histológicas do epitélio da mucosa da árvore traqueobrôn-quica à microscopia óptica. Os autores concluíram que o aquecimento e a umidificação ab...

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OPTIMUM HUMIDIFICATION OF AIR ADMINISTERED TO A TRACHEOSTOMY IN DOGS: Scanning electron microscopy and surfactant studies

Cited by 85 publications

References 20 publications

Influence of Ambient Temperature and Minute Ventilation on Passive and Active Heat and Moisture Exchangers

Influence of Ambient Temperature and Minute Ventilation on Passive and Active Heat and Moisture Exchangers

Airway Humidification Reduces the Inflammatory Response During Mechanical Ventilation

Umidificação e aquecimento do gás inalado durante ventilação artificial com baixo fluxo e fluxo mínimo de gases frescos

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