Impact of Humidification Modality on Incidence of Endotracheal Tube Occlusion in COVID-19 Patients.

Background: Endotracheal tube (ETT) occlusion is reported at a higher frequency among coronavirus disease-2019 (COVID-19) patients. Prior to the COVID-19 pandemic, literature examining patient and ventilator characteristics, including humidification, as etiologies of ETT occlusion yielded mixed results. Our study examines the relationship of humidification modality with ETT occlusion in COVID-19 patients undergoing invasive mechanical ventilation (IMV). Methods: We conducted a retrospective chart review of COVID-19 patients requiring IMV at a tertiary care center in New York from April 2020 to April 2021. Teleflex Neptune heated wire heated humidification (HH) and hygroscopic Intersurgical FiltaTherm and Sunmed Ballard 1500 heat and moisture exchangers (HME) were used. Episodes of ETT occlusion were recorded. Univariate and multivariable logistic regression models were used to investigate the relationship between humidification modality and the occurrence of ETT occlusion. Findings: A total of 201 eligible patients were identified. Teleflex HH was utilized in 50.2% of the population and the others Intersurgical and Sunmed HME devices. Median age was 62 years and 78.6% of patients had at least one medical comorbidity. Precisely, 24% of patients experienced an ETT occlusion after a median of 12 days. The HME group was younger (58.5 vs 64 years), predominantly male (75% vs 59.4%), and experienced more total ventilator days than the HH group (24 vs 12). Those using the studied HME devices had significantly higher odds of ETT occlusion (OR 4.4, 95% CI 1.8-10.6, P = .0011). Three patients (6.1%) experienced cardiac arrest as a consequence of their occlusion. There were no deaths directly attributed to ETT occlusion. Conclusions: The studied HME devices were significantly associated with higher odds of ETT occlusion in COVID-19 patients requiring invasive mechanical ventilation. These events are not without significant clinical consequences. Prolonged use of under-performing HME devices remains suspect in the occurrence of ETT occlusions.

Effects of heated humidification on positive airway pressure side effects in patients with obstructive sleep apnoea: a meta-analysis.

PURPOSE: An earlier study found that heated humidification reduced the side effects of positive airway pressure (PAP) in patients with obstructive sleep apnoea (OSA). However, other studies disagreed with this finding. Therefore, we evaluated the relationship between heated humidification and the side effects of PAP in patients with OSA. METHODS: According to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, six databases were searched for relevant randomised controlled trials (RCTs) performed from January 1999 to June 2021. RESULTS: From 1012 retrieved articles, we identified 9 eligible RCTs. Compared to the control group, the heated humidification group reported improvements in dry nose (pooled standardised mean difference [SMD] = - 0.70, 95% confidence interval [CI] = - 0.96 to - 0.45, I2 = 0%, p < 0.00001), blocked nose (SMD = - 0.47, 95%CI - 0.69 to - 0.25, I2 = 36%, p < 0.0001), runny nose (SMD = - 0.22, 95%CI - 0.44 to 0, I2 = 0%, p = 0.05), dry mouth (SMD = - 0.62, 95%CI - 0.87 to - 0.37, I2 = 0%, p < 0.00001), and dry throat (SMD = - 0.61, 95%CI - 0.90 to - 0.33, I2 = 41%, p < 0.0001), but did not enhance positive airway pressure adherence (pooled mean difference [MD] = 0.24, 95% CI - 0.10 to 0.58, I2 = 0%, p = 0.17). CONCLUSIONS: Heated humidification improved some PAP side effects in patients with OSA but did not increase PAP adherence. Additional large-scale multi-centre RCTs are needed to verify the long-term effects.

Monitoring of Heated Wire Humidifier Hygrometric Performances With Heater Plate Temperature.

BACKGROUND: Under-humidification and associated complications may occur with heated humidifiers. Hygrometric performances of heated wire humidifiers are reduced by high ambient and high outlet ventilator temperatures. Currently, there is no reliable monitoring tool to evaluate humidification performances of heated wire humidifiers in the daily practice. We sought to demonstrate the relation between humidity delivered by heated wire humidifiers and different parameters that could be used to monitor humidity of gas delivered to subjects. METHODS: On a bench test, we measured heater plate temperature, inlet chamber temperature, and delivered humidity with MR850 system. Temperature displayed on the humidifier was also recorded. The measurements were performed at different ambient temperatures and five minute ventilation levels (5, 7.5, 10, 12.5, 15 L/min). Inlet chamber temperatures varied from 20-40°C. In each condition, hygrometric measurements with the psychrometric method were performed at steady state. RESULTS: We performed 279 measurements at steady state including all conditions. We found a good correlation between heater plate temperature and absolute humidity delivered (R2 = 0.82). This relationship was hardly affected by ambient temperature, but minute ventilation had more effect. For different minute ventilations, the correlation between heater plate temperature and absolute humidity delivered was very good with coefficient of determination R2 from 0.87-0.98. Heater plate temperature > 62°C was a good predictor of absolute humidity delivered > 30 mg H2O/L (area under the curve = 0.96, sensibility 79%, specificity 94%). No correlation existed between humidity delivered and the outlet chamber temperature (displayed on the humidifier). CONCLUSIONS: In this bench study, we have shown a good correlation between heater plate temperature and humidity delivered with a heated wire humidifier. This means that a "hidden" hygrometer is built into the heated wire humidifier. Heater plate temperature should be used as a surrogate of humidity to improve the humidification monitoring.

Performance of Invasive Mode in Different Heated Humidification Systems With High-Flow Nasal Cannula.

BACKGROUND: Oxygen therapy via high-flow nasal cannula generates physiologic changes that impact ventilatory variables of patients. However, we know that there are detrimental effects on airway mucosa related to inhalation of gases. The objective of this study was to evaluate the performance in terms of absolute humidity, relative humidity, and temperature of different brands of heated humidifiers and circuits in the invasive mode during the use of high-flow oxygen therapy in flows between 30 and 100 L/min. METHODS: A prospective observational study conducted at the Sanatorio Anchorena equipment analysis laboratory; September 5 to October 20, 2019. RESULTS: A statistically significant interaction was found among the programmed flows and the different combinations of devices and circuits for the delivery of absolute humidity (P < .001). An effect of flow on delivered absolute humidity was found, regardless of the equipment and circuit combination (P < .001). However, in the invasive mode, the combination of the Fisher&Paykel MR850 heated humidifier with the Medtronic-Dar circuit, the Intersurgical circuit, and the AquaVENT circuit always reached or achieved absolute humidity values > 33 mg/L, even at flows up to 100 L/min. The combination of the Flexicare FL9000 heated humidifier with the Fisher&Paykel RT202 circuit, the Fisher&Paykel Evaqua 2 circuit, the Flexicare circuit, the AquaVENT circuit, and the GGM circuit achieved similar results. The mean (SD) of absolute humidity delivered in the invasive mode (36.2 ± 5.9 mg/L) was higher compared with the noninvasive mode (26.8 ± 7.2 mg/L) (P < .001), regardless of circuit and programmed flows. CONCLUSIONS: When heated humidifiers were used in the invasive mode for high-flow oxygen therapy, absolute humidity depended not only on the heated humidifiers and the combination of circuits but also on the programmed flow, especially at flows > 50 L/min. Moreover, the heated humidifiers exhibited different behaviors, in some cases inefficient, in delivering adequate humidification. However, some equipment improved performance when set to the invasive mode.

Impact of Airway Humidification Strategy in Mechanically Ventilated COVID-19 Patients.

BACKGROUND: Humidification of inspiratory gases is mandatory in all mechanically ventilated patients in ICUs, either with heated humidifiers (HHs) or with heat and moisture exchangers (HMEs). In patients with COVID-19, the choice of the humidification device may have relevant impact on patients' management as demonstrated in recent studies. We reported data from 2 ICUs using either HME or HH. METHODS: Data from patients with COVID-19 requiring invasive mechanical ventilation during the first wave in 2 ICUs in Québec City were reviewed. In one ICU, HMEs were used, whereas heated-wire HHs were used in the other ICU. We compared ventilator settings and arterial blood gases at day one after adjustment of ventilator settings. Episodes of endotracheal tube occlusions (ETOs) or subocclusions and a strategy to limit the risk of under-humidification were reported. On a bench test, we measured humidity with psychrometry with HH at different ambient temperature and evaluated the relation with heater plate temperature. RESULTS: We reported data from 20 subjects positive for SARS-Cov-2, including 6 in the ICU using HME and 14 in the ICU using HH. In the HME group, PaCO2 was higher (48 vs 42 mm Hg) despite higher minute ventilation (171 vs 145 mL/kg/min predicted body weight [PBW]). We also reported 3 ETOs occurring in the ICU using HH. The hygrometric bench study reported a strong correlation between heater plate temperatures of the HH and humidity delivered. After implementation of measures to avoid under-humidification, including heater plate temperature monitoring, no more ETOs occurred. CONCLUSIONS: The choice of the humidification device used in subjects with COVID-19 had a relevant impact on ventilation efficiency (increased CO2 removal with lower dead space) and on complications related to low humidity, including ETOs that may be present with heated-wire HHs when used with high ambient temperatures.

Airway Care Interventions for Invasively Ventilated Critically Ill Adults-A Dutch National Survey.

Airway care interventions may prevent accumulation of airway secretions and promote their evacuation, but evidence is scarce. Interventions include heated humidification, nebulization of mucolytics and/or bronchodilators, manual hyperinflation and use of mechanical insufflation-exsufflation (MI-E). Our aim is to identify current airway care practices for invasively ventilated patients in intensive care units (ICU) in the Netherlands. A self-administered web-based survey was sent to a single pre-appointed representative of all ICUs in the Netherlands. Response rate was 85% (72 ICUs). We found substantial heterogeneity in the intensity and combinations of airway care interventions used. Most (81%) ICUs reported using heated humidification as a routine prophylactic intervention. All (100%) responding ICUs used nebulized mucolytics and/or bronchodilators; however, only 43% ICUs reported nebulization as a routine prophylactic intervention. Most (81%) ICUs used manual hyperinflation, although only initiated with a clinical indication like difficult oxygenation. Few (22%) ICUs used MI-E for invasively ventilated patients. Use was always based on the indication of insufficient cough strength or as a continuation of home use. In the Netherlands, use of routine prophylactic airway care interventions is common despite evidence of no benefit. There is an urgent need for evidence of the benefit of these interventions to inform evidence-based guidelines.

Effect of Heated Humidification on CPAP Therapy Adherence in Subjects With Obstructive Sleep Apnea With Nasopharyngeal Symptoms.

BACKGROUND: The addition of heated humidification to CPAP has been shown to improve nasal adverse effects in subjects with obstructive sleep apnea (OSA). However, current data regarding improvement in CPAP adherence is conflicting. Furthermore, there are no data from a tropical climate area with a high humidity level. METHODS: In this prospective randomized crossover study conducted in Thailand, subjects with moderate to severe OSA with nasopharyngeal symptoms post-split-night study were enrolled in the study. Subjects were randomly assigned to receive CPAP with or without heated humidification for 4 weeks and then crossed over. Information on CPAP adherence, quality of life assessed by the Functional Outcomes of Sleep Questionnaire, nasopharyngeal symptoms assessed by a modified XERO questionnaire, and bedroom ambient humidity and temperature data were obtained. RESULTS: Data were collected on 20 subjects with OSA during the period of January to December 2014. Although the addition of heated humidification appeared to improve average hours of use for all days when compared with conventional CPAP, the difference was not statistically significant (CPAP with heated humidification = 4.6 ± 1.7 h/night; conventional CPAP = 4.0 ± 1.7 h/night, P = .1). However, the addition of heated humidification improved CPAP adherence on the days of use (5.5 ± 1.5 h/night) compared with conventional CPAP (5.2 ± 1.4 h/night), P = .033. Quality of life was also improved according to the Functional Outcomes of Sleep Questionnaire score (median 17.6 [interquartile range 3.5]) in the heated humidification group compared with conventional CPAP group (median 17.6 [interquartile range 4.5]), P = .046. Significant reduction in the dry throat/sore throat symptom was noted only when CPAP with heated humidification was used. CONCLUSIONS: Even in a tropical climate area, CPAP adherence and quality of life appeared to improve when heated humidification was employed in subjects with moderate to severe OSA with nasopharyngeal symptoms post-split-night polysomnography. The improvement may be related to a reduction in the dry throat/sore throat symptom.

The application of actively heated humidified high flow nasal cannula oxygen therapy in adults / 中华危重病急救医学

Actively heated, humidified high flow nasal cannula oxygen therapy (HFNC) is a new type of oxygen therapy. Because of its unique physiological effects, the clinical application is becoming more and more popular. This article is to summarize the physiological effects, clinical application and short comings of HFNC. Compared with conventional oxygen therapy, HFNC helps to improve oxygenation better, and it is more comfortable than non-invasive ventilation (NIV) in use. Proper use of HFNC may be able to reduce the use of NIV and decrease the rate of endotracheal intubation. It can be used for adults with mild to moderate hypoxia, or for patients undergoing palliative care. However, the experience of the use of HFNC in adults is limited, and there is yet no corresponding clinical guideline. Therefore, further research with a large sample is required to determine the long-term effect of this technique, and to identify the adult patient population to whom is most beneficial.