PulmonaryPreoxygenation and apneic oxygenation using Transnasal Humidified Rapid-Insufflation Ventilatory Exchange for emergency intubation☆,☆☆
Introduction
Hypoxia is one of the leading causes of anesthesia-related injury in the United Kingdom [1]. It is particularly common during the emergency intubation of patients outside the operating theater environment and associated with severe adverse harm in this patient group [2], [3]. The techniques of preoxygenation and rapid sequence induction (RSI) have developed to minimize the risk of hypoxia during intubation.
Preoxygenation describes the process of maximizing the amount of oxygen stored in the body before induction of anesthesia. The most important store of oxygen is the functional residual capacity (FRC), the volume of gas present at the end of passive expiration. The amount of oxygen contained in the FRC can be improved by (1) increasing the inspired Fio2 to denitrogenate the FRC, (2) applying continuous positive airway pressure (CPAP) to minimize airway atelectasis, and (3) positioning the patient in a head up (25°-35°) to increase the available volume of the FRC.
Rapid sequence induction describes the sequential process of (1) preoxygenation, (2) administration of a predetermined dose of induction agent, (3) administration of a predetermined dose of muscle relaxant, (4) avoidance of positive pressure ventilation, and (5) confirmation of tracheal intubation. It is thought that this approach minimizes the duration of time the airway is unprotected and avoids gastric insufflation, thereby reducing the risk of aspiration.
Adequate preoxygenation and RSI have become cornerstones of safe anesthetic practice. These techniques are considered to be particularly useful for patients with high metabolic rates, respiratory pathology, or a reduced FRC, who have either a higher oxygen requirement or a lower oxygen storage capacity and are therefore likely to develop hypoxia (desaturate) more rapidly. However, despite apparent adequate preoxygenation and RSI, desaturation can still occur within 60 seconds in susceptible patients [4]. This limitation of conventional preoxygenation and RSI has led to renewed interest in the use of apneic oxygenation to extend the period of time that a patient maintains adequate oxygenation after induction of anesthesia, but before intubation.
Apneic oxygenation occurs in response to differences in solubility of oxygen and carbon dioxide. After the onset of apnea, oxygen continues to diffuse from the alveolar air space into the blood at a rate of approximately 250 mL/min. At the same time, carbon dioxide continues to diffuse from the blood into the alveolar air space at a rate of approximately 200 mL/min. This results in an initial volume deficit of 50 mL/min in the alveolar air space. In the absence of ventilation, carbon dioxide accumulates in the alveolar air space and approaches equilibrium with carbon dioxide in the blood. As a consequence, carbon dioxide diffusion falls to approximately 10 mL/min after approximately 45 seconds and the difference between the volume of oxygen leaving and the volume of carbon dioxide entering the alveolar air space is approximately 240 mL/min [5]. This discrepancy generates a negative pressure gradient between the alveolus and the upper airway, promoting the flow of gas from the pharynx to the alveolus, provided that the upper airway is patent. If the upper airway is insufflated with 100% oxygen, apneic oxygenation provides a mechanism to replenish the oxygen stored in the FRC at a rate approximately equal to rate oxygen diffuses across the alveolar membrane and so extend the duration of adequate oxygenation during periods of apnea [6], [7].
Recently, humidified high-flow nasal oxygenation, known as Transnasal Humidified Rapid-Insufflation Ventilatory Exchange (THRIVE), has been investigated as a mechanism of providing both preoxygenation and apneic oxygenation in elective surgical patients, and reported to extend oxygen saturations during laryngoscopy and highly specialized airway surgery from a few minutes to more than 1 hour in some cases with relatively modest rises in carbon dioxide [7]. The beneficial effects of THRIVE in maintaining hemoglobin saturation (Spo2) have also been demonstrated during the emergency intubation of critical care patients [8].
We hypothesized that preoxygenation and apneic oxygenation using THRIVE would be associated with a low incidence of desaturation during the emergency intubation of patients at high risk of hypoxia in our hospital. We report the findings of our pilot study, demonstrating the practicalities and results of implementing a THRIVE protocol in our critical care unit (CCU), operating room (OR), and emergency department (ED).
Section snippets
Material and methods
This prospective, observational study was conducted at the Queen Elizabeth Hospital, Norfolk, UK. As the data were collected as part of delivering routine care after a change of practice at the institution for audit, service surveillance, and improvement purposes, and anonymized, formal ethical committee approval was not sought. However, the Chair of the Research Governance Committee and Caldicott Guardian were consulted for approval to report data from routine practice and for publication of
Results
Data were collected from 71 sequential patients. The demographic details and patient comorbidities are shown in Table 1. The location and reason for intubation are shown in Table 2. The risk factors for desaturation are shown in Table 3. The grade at laryngoscopy ranged from 1 to 4 (grade 1, 59%; grade 2, 27%; grade 3, 13%; grade 4, 1%). Thirteen cases required ≥2 attempts at laryngoscopy before successful intubation (3 (23%) of which underwent significant desaturation). Difficult airway
Discussion
Hypoxia is one of the most common and serious risks of tracheal intubation [1], [2], [3]. There is a growing body of evidence that apneic oxygenation has the potential to minimize the risk of hypoxia in patients requiring intubation. In 2, small, randomized controlled studies in healthy patients, insufflating oxygen at a flow rate of 3 to 5 L/min via a nasal catheter in apneic individuals extended the period of time that adequate oxygenation was maintained from 6 to 10 minutes in contrast to
Conclusions
In conclusion, our study demonstrated that preoxygenation and apneic oxygenation using THRIVE were associated with a low incidence of desaturation during emergency intubation of patients at high risk of hypoxia in the CCU, OR, and ED. Transnasal Humidified Rapid-Insufflation Ventilatory Exchange has the potential to minimize the risk of hypoxia in these patient groups.
Acknowledgments
None.
References (16)
- et al.
major Complications of airway management in the UK: results of the fourth National Audit Project of the Royal College of Anaesthetists and the difficult airway society. Part 1: anaesthesia
Br J Anaesth
(2011) - et al.
major Complications of airway management in the UK: results of the fourth National Audit Project of the Royal College of Anaesthetists and the difficult airway society. Part 2: intensive care and emergency departments
Br J Anaesth
(2011) - et al.
A model to describe the rate of oxyhaemoglobin desaturation during apnoea
Br J Anaesth
(1996) - et al.
Apneic oxygenation during prolonged laryngoscopy in obese patients: a randomized, controlled trial of nasal oxygen administration
J Clin Anesth
(2010) - et al.
Apneic oxygenation was associated with decreased desaturation rates during rapid sequence intubation by an Australian helicopter emergency medicine service
Ann Emerg Med
(2015) - et al.
Oxygen delivery through high-flow nasal cannulae increase end-expiratory lung volume and reduce respiratory rate in post-cardiac surgical patients
Br J Anaesth
(2011) - et al.
Effectiveness of preoxygenation in morbidly obese patients
Br J Anaesth
(1991) - et al.
The who, where, and what of rapid sequence intubation: prospective observational study of emergency RSI outside the operating theatre
Emerg Med J
(2004)
Cited by (33)
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2021, Trends in Anaesthesia and Critical CareCitation Excerpt :The device can deliver a highly oxygenated flow to the alveoli because of its ability to provide higher flow rates than the usual and to reduce the entrainment of room air. HFNO generates a low level of continuous positive airway pressure of 2–7 cmH2O, facilitates the washout of the nasopharyngeal dead space, reduces the nasopharyngeal resistance, might increase alveolar recruitment and might decrease the work of breathing and also might prevent the development of atelectasis and bronchospasm [16,17]. The ability to deliver warmed and humidified oxygen needs a specially designed technique of HFNO that prevents the feeling of dryness in the nasal cavity of patients and promotes tolerance for the high-flow rate.
Effect of variable pre-oxygenation endpoints on safe apnoea time using high flow nasal oxygen for women in labour: a modelling investigation
2021, British Journal of AnaesthesiaPhysiologically difficult airway in critically ill patients: winning the race between haemoglobin desaturation and tracheal intubation
2020, British Journal of AnaesthesiaNonintubated laryngomicrosurgery with Transnasal Humidified Rapid-Insufflation Ventilatory Exchange: A case series
2019, Journal of the Formosan Medical AssociationCitation Excerpt :The intermittent apnoea method is usually performed in procedures that last less than 10 min. Apnoeic ventilation under THRIVE can extend the apnoea time up to 65 min12,14,20 and thus can be used as oxygen support for longer LMS procedures. Our results are consistent with the results of these studies and reveal that by applying adequate preoxygenation and maintaining high-flow nasal oxygen at a rate of 50 L min−1, the safe apnea time could be extended to 12.7 min on average for vocal cord surgery.
THRIVE? The answer, my friend, is blowing in the (high flow) wind!
2018, Trends in Anaesthesia and Critical Care
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Conflict of interest: Dr Young has received honoraria for UK presentations from Fisher and Paykel Healthcare.
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Sources of financial support: Funding was awarded from Queen Elizabeth Hospital King's Lynn Research Fund, Kings Lynn, UK.
Equipment and consumables for Optiflow oxygenation system supplied by Fisher and Paykel Healthcare Limited, Panmure, Auckland, New Zealand.
Each funding source had no involvement in study design; in the collection, analysis, and interpretation of data; in the writing of the report; and in the decision to submit the article for publication.