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End-Tidal Oxygen for Intubation in the Emergency Department

RECRUITING

Rapid Sequence Intubation (RSI) is a high-risk procedure in the emergency department (ED). Patients are routinely preoxygenated (given supplemental oxygen) prior to RSI to prevent hypoxia during intubation. For many years anaesthetists have used end-tidal oxygen (ETO2) levels to guide the effectiveness of preoxygenation prior to intubation.

The ETO2 gives an objective measurement of preoxygenation efficacy. This is currently not available in most EDs. This trial evaluates the use of ETO2 on the rate of hypoxia during intubation for patients in the ED.

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Study details:

BACKGROUND AND INTRODUCTION. Rapid Sequence Intubation (RSI) is a common procedure in Emergency Departments (ED). However, it is a high-risk procedure and is associated with significant complications including hypoxia, failed intubation, hypotension, trauma and aspiration.

(1-3) Specifically, hypoxia during intubation can lead to poor outcomes such as dysrhythmias, haemodynamic compromise, hypoxic brain injury and death and therefore oxygen desaturation is of primary concern during any intubation procedure. (4, 5) In order to prevent desaturation events during intubation, a number of steps are taken by clinicians. These include optimal patient positioning, adequate preoxygenation, assessment of airway anatomy and development of a detailed airway plan as well as the use of apnoeic oxygenation.

(6). Effective preoxygenation is vital to ensure that the patient does not develop hypoxia during the period between induction (administration of sedative and paralytic agents) and restoration of ventilation by successful endotracheal intubation or rescue breathing. Various methods of preoxygenation have been developed to wash the nitrogen out of the lungs (denitrogenation) which allows the functional residual capacity (FRC) to act as an oxygen reservoir during intubation, which prolongs safe apnoea time, therefore, preventing desaturation whilst an endotracheal tube (ETT) is placed.

Adequate preoxygenation is especially important for those patients at highest risk of hypoxia during the RSI. This patient group includes those with underlying lung pathology e. g.

pneumonia, patients with increased metabolic demand e. g. sepsis, patients with an oxygen requirement prior to RSI, or patients with underlying conditions that predisposes to hypoxia e.

g. obesity. For many years anaesthetists have used end-tidal oxygen (ETO2) levels to guide the effectiveness of preoxygenation.

ETO2 measures the exhaled oxygen concentration and is a marker of the oxygen concentration in the alveoli. Prior to induction, anaesthetists most commonly preoxygenate with a face-mask seal via either a circle circuit, Mapleson circuit, or bag valve mask. ETO2 provides an objective measurement of preoxygenation efficacy.

The Difficult Airway Society guidelines suggest aiming for an ETO2 of ≥87% prior to commencing RSI. (7) ETO2 levels are not routinely measured in Emergency Departments. Currently, it is not possible to measure the effectiveness of preoxygenation in the ED.

Pulse-wave oximetry reflects peripheral oxygen saturation and not the pulmonary oxygen concentration. Therefore, to attempt to optimize preoxygenation the emergency clinician currently can only use time as a surrogate. The typically recommended duration of preoxygenation is \> 3 minutes.

Recently, the investigators conducted two multi-site studies (Ethics identifier: 2019/ETH06644) that investigated the use of ETO2 in the ED. (8, 9) The first study was conducted with clinicians blinded to the ETO2 result (8). The investigators demonstrated that preoxygenation was uniformly poor with only 26% of patients achieving the required target ETO2 of ≥85%.

The investigators then completed a second study where clinicians had access to ETO2 values and found that the proportion of patients reaching levels ≥85% was improved to 67% of patients. (9) The prevalence of hypoxemia (SpO2 \<90%) in the group blinded to ETO2 was 18% (n=18, 95% CI: 11% to 27%) and was 8% in the group where ETO2 was available (n = 8, 95% CI: 4% to 15%). These studies indicate that the use of ETO2 may substantially improve preoxygenation in the ED and therefore reduce the risk of hypoxia.

These studies, however, were focused on preoxygenation practices and not patient-oriented outcomes (hypoxia) and were limited in design and resources. Consequently, it is still unclear whether the use of ETO2 in the ED leads to improved clinical outcomes. RATIONALE FOR PERFORMING THE STUDY.

The aim of this study is to determine the effectiveness of ETO2 monitoring in preventing desaturation for patients with a high risk of hypoxia undergoing RSI in ED. HYPOTHESIS. The investigators hypothesise that the use of ETO2 monitoring leads to reduced rates of oxygen desaturation during the peri-intubation period compared to when it is not used.

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Eligibility criteria

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Inclusion criteria

The patient is located in the ED resuscitation bay of the participating centre.

The planned procedure is orotracheal intubation using a laryngoscope and RSI technique with preoxygenation for patients who are spontaneously breathing.

The patient is deemed to be at a high risk of hypoxia during RSI as per the treating ED clinician, as defined by:

Any patient requiring any form of oxygen therapy before preoxygenation.

Any patient with respiratory pathology based on clinical or radiological findings. Including, but not limited to:

Pneumonia, pulmonary oedema, acute respiratory distress syndrome (ARDS), aspiration, pulmonary contusion from trauma, infective exacerbations of known lung disease (e.g. asthma, pulmonary fibrosis, emphysema) or pulmonary embolism (PE)

Any patient with high oxygen consumption. Including, but not limited to:

Sepsis, Diabetic ketoacidosis, alcohol or drug withdrawal, seizures, thyrotoxicosis

Any underlying patient condition that may predispose to hypoxemia. Including, but not limited to:

Obesity, pregnancy, underlying lung disease (e.g. asthma, pulmonary fibrosis, emphysema), severe injury- hypovolaemia/haemorrhage.

or any other patient that the treating clinician has a high concern for hypoxemia during RSI.

Exclusion criteria

Patient is known to be less than 18 years old.

The patient has a supraglottic device in-situ e.g iGel or LMA.

The patient is known to be pregnant.

The patient is known to be a prisoner.

The patient was intubated in the prehospital environment.

Immediate need for tracheal intubation precludes preoxygenation i.e. the patient is in cardiac arrest.

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Eligibility

Age eligible for study : 18 and older

Healthy volunteers accepted : No

Gender eligible for study: All

Things to know

Study dates

Study start: 2024-08-05

Primary completion: 2025-12-31

Study completion finish: 2025-12-31

Study type

DIAGNOSTIC

Phase

Trial ID

NCT06578468

Intervention or treatment

DEVICE: End-tidal oxygen monitor

Conditions

• Critical Illness
• Hypoxia
• Respiratory Failure

Condition: Critical Illness, Hypoxia and more
DEVICE: End-tidal oxygen monitor
Sydney, New South Wales, Australia and more
Sponsor: Sydney Local Health District

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Find a site

Closest Location:

Royal Prince Alfred Hospital

Research sites nearby

Select from list below to view details:

Royal Prince Alfred Hospital
Sydney, New South Wales, Australia
Royal North Shore Hospital
Sydney, New South Wales, Australia
Westmead Hospital
Sydney, New South Wales, Australia
Liverpool Hospital
Sydney, New South Wales, Australia

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Participant Group/Arm	Intervention/Treatment
NO_INTERVENTION: Control period The control period includes a period whereby clinicians will not have access to ETO2 monitoring and routine RSI practices will be documented including all study variables. At all institutions, RSI is performed in a similar manner, utilising an airway checklist. There is no 'standard operating procedure' for RSI in any of the EDs and methods, therefore, vary depending on clinician preference and the condition of the patient, however, each site is a tertiary-level, university teaching hospital and therefore clinical practice is up to date and evidence-based. Standard preoxygenation methods in the Emergency department often consist of a bag-valve mask, with or without a PEEP valve, set at 15L/min, or the use of non-invasive ventilation or a non-rebreather mask, with or without a nasal cannula, set at 15 L/min or flush rate oxygen (\>40 L/min). US sites have access to high-flow (\>30L/min) oxygen. This is the only difference in the preoxygenation method.	Not specified
EXPERIMENTAL: Study period For all patients involved in the study, the only intervention will be the use of ETO2 to guide preoxygenation. All aspects of RSI will be at the discretion of the treating clinician including sedative/paralytic medications, positioning of the patient, preoxygenation method, intubation techniques and post-intubation sedation. Clinicians will be encouraged to aim for the highest ETO2 result possible with a goal of \>85%. Clinicians will be able to view the ETO2 values and can decide on any changes to the preoxygenation techniques if deemed necessary. These techniques may include improved patient positioning, improved face mask seal, increased oxygen flow, length of preoxygenation time, or altering the preoxygenation device.	DEVICE: End-tidal oxygen monitor The only additional equipment required for this study is the Philips™ IntelliVue G7m Gas Analyser Module 866173. This provides a non-dispersive infrared measurement of respiratory gases and a paramagnetic measurement of oxygen. At Lincoln Medical Center, the gas analyser used will be a Philips G5 gas analyser connected to a Philips Intellivue MP 70. At the University of New Mexico Medical Center, the Masimo root monitor is used. The gas analysers produce display waves for O2 and CO2, together with numerics for end-tidal values for O2 and CO2 and to our knowledge, there are no differences in values between the various devices used. The gas sampling occurs through a side-stream sampling tube at a rate of 200ml/min ±20 ml/min, which is either obtained from a nasal cannula in the spontaneously breathing patient or a sidestream line if connected to a BVM.

Participant Group/Arm

Intervention/Treatment

NO_INTERVENTION: Control period

The control period includes a period whereby clinicians will not have access to ETO2 monitoring and routine RSI practices will be documented including all study variables. At all institutions, RSI is performed in a similar manner, utilising an airway checklist. There is no 'standard operating procedure' for RSI in any of the EDs and methods, therefore, vary depending on clinician preference and the condition of the patient, however, each site is a tertiary-level, university teaching hospital and therefore clinical practice is up to date and evidence-based. Standard preoxygenation methods in the Emergency department often consist of a bag-valve mask, with or without a PEEP valve, set at 15L/min, or the use of non-invasive ventilation or a non-rebreather mask, with or without a nasal cannula, set at 15 L/min or flush rate oxygen (\>40 L/min). US sites have access to high-flow (\>30L/min) oxygen. This is the only difference in the preoxygenation method.

Not specified

EXPERIMENTAL: Study period

For all patients involved in the study, the only intervention will be the use of ETO2 to guide preoxygenation. All aspects of RSI will be at the discretion of the treating clinician including sedative/paralytic medications, positioning of the patient, preoxygenation method, intubation techniques and post-intubation sedation.
Clinicians will be encouraged to aim for the highest ETO2 result possible with a goal of \>85%. Clinicians will be able to view the ETO2 values and can decide on any changes to the preoxygenation techniques if deemed necessary. These techniques may include improved patient positioning, improved face mask seal, increased oxygen flow, length of preoxygenation time, or altering the preoxygenation device.

DEVICE: End-tidal oxygen monitor

The only additional equipment required for this study is the Philips™ IntelliVue G7m Gas Analyser Module 866173. This provides a non-dispersive infrared measurement of respiratory gases and a paramagnetic measurement of oxygen. At Lincoln Medical Center, the gas analyser used will be a Philips G5 gas analyser connected to a Philips Intellivue MP 70. At the University of New Mexico Medical Center, the Masimo root monitor is used.
The gas analysers produce display waves for O2 and CO2, together with numerics for end-tidal values for O2 and CO2 and to our knowledge, there are no differences in values between the various devices used. The gas sampling occurs through a side-stream sampling tube at a rate of 200ml/min ±20 ml/min, which is either obtained from a nasal cannula in the spontaneously breathing patient or a sidestream line if connected to a BVM.

What is the study measuring?

Primary outcome

Primary Outcome Measure	Primary Outcome Description	Primary Outcome Time Frame
Incidence of hypoxia	The proportion of patients that experience oxygenation desaturation (SpO2 \<93%, or \>10% from baseline if SpO2 \<93% at the end of preoxygenation) during the peri-intubation period	The time when laryngoscope first enters the mouth to 2 minutes after the endotracheal tube [ETT] is confirmed on waveform capnography

Secondary outcome

Secondary Outcome Measure	Secondary Outcome Description	Secondary Outcome Time Frame
Lowest oxygen saturations	The lowest oxygen saturation (SpO2) during the peri-intubation period	The time when laryngoscope first enters the mouth to 2 minutes after the endotracheal tube [ETT] is confirmed on waveform capnography

Frequently Asked Questions

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References

Clinical Trials Gov: End-Tidal Oxygen for Intubation in the Emergency Department