Oxygen therapy in the pre-hospital setting for acute exacerbations of chronic obstructive pulmonary disease

Standard vs. targeted oxygen therapy prehospitally for chronic obstructive pulmonary disease (STOP-COPD): study protocol for a randomised controlled trial

BACKGROUND

A high concentration of inspired supplemental oxygen may possibly cause hypercapnia and acidosis and increase mortality in patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD). Even so, patients with AECOPD are being treated with high oxygen flow rates when receiving inhalation drugs in the prehospital setting. A cluster-randomised controlled trial found that reduced oxygen delivery by titrated treatment reduced mortality-a result supported by observational studies-but the results have never been reproduced. In the STOP-COPD trial, we investigate the effect of titrated oxygen delivery compared with usual care consisting of high flow oxygen delivery in patients with AECOPD in the prehospital setting.

METHODS

In this randomised controlled trial, patients will be blinded to allocation. Patients with suspected AECOPD (n = 1888) attended by the emergency medical service (EMS) and aged > 40 years will be allocated randomly to either standard treatment or titrated oxygen, targeting a blood oxygen saturation of 88-92% during inhalation therapy. The trial will be conducted in the Central Denmark Region and include all ambulance units. The power to detect a 3% 30-day mortality risk difference is 80%. The trial is approved as an emergency trial. Hence, EMS providers will include patients without prior consent.

DISCUSSION

The results will provide evidence on whether titrated oxygen delivery outperforms standard high flow oxygen when used to nebulise inhaled bronchodilators in AECOPD treatment. The trial is designed to ensure unselected inclusion of patients with AECOPD needing nebulised bronchodilators-a group of patients that receives high oxygen fractions when treated in the prehospital setting where the only compressed gas is generally pure oxygen. Conducting this trial, we aim to improve treatment for people with AECOPD while reducing their 30-day mortality.

TRIAL REGISTRATION

European Union Clinical Trials (EUCT) number: 2022-502003-30-00 (authorised 06/12/2022), ClinicalTrials.gov number: NCT05703919 (released 02/02/2023), Universal trial number: U1111-1278-2162.

[Oxygen therapy in intensive care]

PULSE OXIMETRY AND BLOOD GAS ANALYSES

Pulse oximetry has high sensitivity but low specificity for detecting hypoxemia. Arterial blood gas analyses are the gold standard for monitoring O2 therapy. Venous blood gas analyses should not be used in this setting. TARGET VALUES OF O2 THERAPY: The target range of acute O2 therapy for ventilated patients and nonventilated patients not at risk of hypercapnia should be between 92% and 96% for oxygen saturation (SpO2) measured by pulse oximetry. Indications for high-dose O2 therapy without a target range in critical care include carbon monoxide poisoning and patients with severe respiratory distress when SpO2 cannot be derived. Hyperoxemia, i.e., SpO2 values above 96%, has not improved survival in randomized trials of predominantly ventilated ICU patients. Under hyperoxemia in nonventilated patients at risk of hypercapnia (e.g., patients with chronic obstructive pulmonary disease), one in three patients is at risk of increasing carbon dioxide. Therefore, a target SpO2 of 88-92% should be aimed for in these patients. O2 TARGET RANGES ON EXTRACORPOREAL PROCEDURES: There are no randomized studies recommending other SpO2 target ranges for patients on extracorporeal procedures. These patients should always be monitored with arterial blood gases-in the case of peripheral VA-ECMO on the right arm and downstream of the oxygenator. HIGH-FLOW OXYGEN THERAPY FOR ACUTE HYPERCAPNIC RESPIRATORY FAILURE: High-flow oxygen therapy (HFNC) was not associated with reduced in-hospital mortality compared with conventional O2 in a meta-analysis of predominantly patients with acute hypoxemia (type I respiratory failure), although intubation rates were reduced. Also, in acute hypercapnic respiratory failure (type II), HFNC with high flow rates is not inferior to noninvasive ventilation (NIV).

[Oxygen in the acute care of adults : Short version of the German S3 guideline]

BACKGROUND

Oxygen is a drug with specific properties, a defined dose-effect range and side effects. In 2015, in a sample of UK hospital patients, 14% were treated with oxygen, of which only 42% had a prescription. Health care workers are often uncertain about the relevance of hypoxemia, and there is limited awareness of the risks of hyperoxemia. Numerous randomized controlled trials on oxygen therapy have recently been published.

METHODS

As part of the guideline program of the Working Group of Scientific Medical Societies e. V. (AWMF), this S3 guideline was developed with the participation of 10 medical societies on the basis of a literature search up to 02/01/2021. The system of the Oxford Centre for Evidence-Based Medicine (CEBM) (The Oxford 2011 Levels of Evidence) was used to evaluate the literature. The quality of evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE), and a formal consensus process of recommendations was performed.

RESULTS

The guideline contains 34 evidence-based recommendations on the indication, prescription, monitoring, and discontinuation of oxygen therapy in acute care. The indication for oxygen is mainly hypoxemia. Hypoxemia and hyperoxemia should be avoided, since both increase mortality. The guideline recommends target ranges of oxygen saturation for acute oxygen therapy without differentiating between different diagnoses. Target areas depend on the risk for hypercapnia and ventilation status. The guideline provides an overview of available oxygen delivery systems and contains recommendations for their selection based on patient safety and comfort.

CONCLUSION

This is the first German guideline on the use of oxygen in acute care. It is aimed at medical professionals who use oxygen in and outside hospitals and is valid until June 30th, 2024.

German S3 Guideline: Oxygen Therapy in the Acute Care of Adult Patients

BACKGROUND

Oxygen (O2) is a drug with specific biochemical and physiological properties, a range of effective doses and may have side effects. In 2015, 14% of over 55,000 hospital patients in the UK were using oxygen. 42% of patients received this supplemental oxygen without a valid prescription. Health care professionals are frequently uncertain about the relevance of hypoxemia and have low awareness about the risks of hyperoxemia. Numerous randomized controlled trials about targets of oxygen therapy have been published in recent years. A national guideline is urgently needed.

METHODS

A national S3 guideline was developed and published within the Program for National Disease Management Guidelines (AWMF) with participation of 10 medical associations. A literature search was performed until February 1, 2021, to answer 10 key questions. The Oxford Centre for Evidence-Based Medicine (CEBM) System ("The Oxford 2011 Levels of Evidence") was used to classify types of studies in terms of validity. Grading of Recommendations, Assessment, Development and Evaluation (GRADE) was used for assessing the quality of evidence and for grading guideline recommendation, and a formal consensus-building process was performed.

RESULTS

The guideline includes 34 evidence-based recommendations about indications, prescription, monitoring and discontinuation of oxygen therapy in acute care. The main indication for O2 therapy is hypoxemia. In acute care both hypoxemia and hyperoxemia should be avoided. Hyperoxemia also seems to be associated with increased mortality, especially in patients with hypercapnia. The guideline provides recommended target oxygen saturation for acute medicine without differentiating between diagnoses. Target ranges for oxygen saturation are based depending on ventilation status risk for hypercapnia. The guideline provides an overview of available oxygen delivery systems and includes recommendations for their selection based on patient safety and comfort.

CONCLUSION

This is the first national guideline on the use of oxygen in acute care. It addresses health care professionals using oxygen in acute out-of-hospital and in-hospital settings.

ORi™: a new indicator of oxygenation

In the perioperative period, hypoxemia and hyperoxia are crucial factors that require attention, because they greatly affect patient prognoses. The pulse oximeter has been the only noninvasive monitor that can be used as a reference of oxygenation in current anesthetic management; however, in recent years, a new monitoring method that uses the oxygen reserve index (ORi™) has been developed by Masimo Corp. ORi is an index that reflects the state of moderate hyperoxia (partial pressure of arterial oxygen [PaO2] between 100 and 200 mmHg) using a non-unit scale between 0.00 and 1.00. ORi monitoring performed together with percutaneous oxygen saturation (SpO2) measurements may become an important technique in the field of anesthetic management, for measuring oxygenation reserve capacity. By measuring ORi, it is possible to predict hypoxemia and to detect hyperoxia at an early stage. In this review, we summarize the method of ORi, cautions for its use, and suitable cases for its use. In the near future, the monitoring of oxygen concentrations using ORi may become increasingly common for the management of respiratory function before, after, and during surgery.

2021 Guideline for the Management of COPD Exacerbations: Emergency Medicine Association of Turkey (EMAT) / Turkish Thoracic Society (TTS) Clinical Practice Guideline Task Force

Chronic obstructive pulmonary disease (COPD) is an important public health problem that manifests with exacerbations and causes serious mortality and morbidity in both developed and developing countries. COPD exacerbations usually present to emergency departments, where these patients are diagnosed and treated. Therefore, the Emergency Medicine Association of Turkey and the Turkish Thoracic Society jointly wanted to implement a guideline that evaluates the management of COPD exacerbations according to the current literature and provides evidence-based recommendations. In the management of COPD exacerbations, we aim to support the decision-making process of clinicians dealing with these patients in the emergency setting.