High‐flow nasal therapy – modelling the mechanism

Lumb, Andrew B; Thomas, C.

doi:10.1111/anae.14544

Cited by 8 publications

(8 citation statements)

References 28 publications

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“…22 HFNO can also generate positive pharyngeal pressure; however, this is quantitatively low and inconsistent. 22 Groves and Tobin demonstrated that positive expiratory pressure is generated in a flow-dependent manner during SV, which is more pronounced with the mouth closed. 23 The pressure generated by 70 L/ min during suspension laryngoscopy, which is equivalent to an open mouth, equates to 3 cm H 2 O in SV patients.…”

Section: Discussionmentioning

confidence: 99%

The Effect of High-Flow Nasal Oxygen on Carbon Dioxide Accumulation in Apneic or Spontaneously Breathing Adults During Airway Surgery: A Randomized-Controlled Trial

Booth

Vidhani

Lee³

et al. 2020

Anesthesia &Amp; Analgesia

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BACKGROUND: High-flow nasal oxygen (HFNO) is an emerging technology that has generated interest in tubeless anesthesia for airway surgery. HFNO has been shown to maintain oxygenation and CO2 clearance in spontaneously breathing patients and is an effective approach to apneic oxygenation. Although it has been suggested that HFNO can enhance CO2 clearance during apnea, this has not been established. The true extent of CO2 accumulation and resulting acidosis using HFNO during prolonged tubeless anesthesia remains undefined. METHODS: In a single-center trial, we randomly assigned 20 adults undergoing microlaryngoscopy to apnea or spontaneous ventilation (SV) using HFNO during 30 minutes of tubeless anesthesia. Serial arterial blood gas analysis was performed during preoxygenation and general anesthesia. The primary outcome was the partial pressure of CO2 (Paco 2) after 30 minutes of general anesthesia, with each group compared using a Student t test. RESULTS: Nineteen patients completed the study protocol (9 in the SV group and 10 in the apnea group). The mean (standard deviation [SD]) Paco 2 was 89.0 mm Hg (16.5 mm Hg) in the apnea group and 55.2 mm Hg (7.2 mm Hg) in the SV group (difference in means, 33.8; 95% confidence interval [CI], 20.6–47.0) after 30 minutes of general anesthesia (P < .001). The average rate of Paco 2 rise during 30 minutes of general anesthesia was 1.8 mm Hg/min (SD = 0.5 mm Hg/min) in the apnea group and 0.8 mm Hg/min (SD = 0.3 mm Hg/min) in the SV group. The mean (SD) pH was 7.11 (0.04) in the apnea group and 7.29 (0.06) in the SV group (P < .001) at 30 minutes. Five (55%) of the apneic patients had a pH <7.10, of which the lowest measurement was 7.057. No significant difference in partial pressure of arterial O2 (Pao 2) was observed after 30 minutes of general anesthesia. CONCLUSIONS: CO2 accumulation during apnea was more than double that of SV after 30 minutes of tubeless anesthesia using HFNO. The use of robust measurement confirms that apnea with HFNO is limited by CO2 accumulation and the concomitant severe respiratory acidosis, in contrast to SV. This extends previous knowledge and has implications for the safe application of HFNO during prolonged procedures.

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Section: Discussionmentioning

confidence: 99%

The Effect of High-Flow Nasal Oxygen on Carbon Dioxide Accumulation in Apneic or Spontaneously Breathing Adults During Airway Surgery: A Randomized-Controlled Trial

Booth

Vidhani

Lee³

et al. 2020

Anesthesia &Amp; Analgesia

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“…They supply warmed, humidified oxygen at up to 70l/min. They have been shown to improve tissue oxygenation as well as significantly delay oxygen desaturation, even in apneic patients, as well as a means of ventilatory support [ 1 - 3 ]. Standard nasal oxygen cannulas are widely used in the healthcare setting since their introduction in the 1940s and have remained largely unchanged to the present day.…”

Section: Introductionmentioning

confidence: 99%

A Volunteer Crossover Feasibility Study to Compare Standard Oxygen Cannula Used at High-Flow to Proprietary High-Flow Humidified Nasal Oxygen Systems

Johnson¹,

Devine²,

Marshall³

2023

Cureus

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Background and aim: Supplemental oxygen is routinely administered to patients prior to and during induction of general anesthesia and sedation. This increases the fraction of oxygen in the lungs, increases oxygen delivery, and increases the time to oxygen desaturation. Proprietary Transnasal Humidified Rapid-Insufflation Ventilatory Exchange (THRIVE) systems, which deliver warmed and humidified oxygen, have been extensively researched in the perioperative and critical care setting and have been shown to significantly prolong time to desaturation and as a means of ventilatory support. The use of traditional nasal oxygen cannula used at maximum flow rates is currently used in short bursts as it is poorly tolerated. There is however a dearth of data examining the use of this technique. We hypothesized that traditional nasal oxygen cannulae used at maximum flow rates can deliver oxygen as effectively as THRIVE in this setting.Methods: We designed a crossover volunteer feasibility study. The participants were 10 healthy anesthetists. We compared the two methods of oxygen delivery by measuring transcutaneous oxygen measurement and pharyngeal oxygen concentration. Comfort and noise levels were recorded. The aforementioned parameters were compared between the two groups.Results: We observed that a standard oxygen cannula used at high flows delivers comparable oxygen delivery and tissue oxygenation performance to proprietary THRIVE systems. However, they are less comfortable and make more noise. Discussion: To the authors' knowledge this study is the first to study the oxygen delivery of traditional nasal oxygen cannula used at maximum flow rates and make comparisons to the well-studied THRIVE technique. While similar transcutaneous partial pressure of oxygen and pharyngeal gas concentrations were observed with both techniques, the standard cannulae were deemed to be a lot less comfortable than THRIVE and made a lot more noise which likely limit the utility of this technique outside of short bursts.Conclusion: In this study, a standard nasal oxygen cannula used at high flows achieved similar oxygen delivery to THRIVE at the expense of poor comfort and increased noise.

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“…Other physiological benefits of high‐flow nasal oxygen are apparent in spontaneously‐breathing patients, including: reduction of functional dead space; generation of flow‐dependent positive end‐expiratory pressure; and decreased work of breathing. These diverse spontaneous ventilation benefits may be more accurately described as high‐flow nasal therapy, and show promise in improving patient‐centred outcomes when applied postoperatively . Overall, it is clear that the development of this technology represents a significant advance in a myriad of settings, and further applications are likely to be discovered.…”

mentioning

confidence: 99%

Carbon dioxide clearance during apnoea with high‐flow nasal oxygen: epiphenomenon or a failure to THRIVE?

Toner

2019

Anaesthesia

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High‐flow nasal therapy – modelling the mechanism

Cited by 8 publications

References 28 publications

The Effect of High-Flow Nasal Oxygen on Carbon Dioxide Accumulation in Apneic or Spontaneously Breathing Adults During Airway Surgery: A Randomized-Controlled Trial

The Effect of High-Flow Nasal Oxygen on Carbon Dioxide Accumulation in Apneic or Spontaneously Breathing Adults During Airway Surgery: A Randomized-Controlled Trial

A Volunteer Crossover Feasibility Study to Compare Standard Oxygen Cannula Used at High-Flow to Proprietary High-Flow Humidified Nasal Oxygen Systems

Carbon dioxide clearance during apnoea with high‐flow nasal oxygen: epiphenomenon or a failure to THRIVE?

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