Contemporary emergency paramedic practice is largely derived from modern advance life support courses that include advanced trauma life support (ATLS), advanced paediatric life support (APLS), and advanced life support (ALS). These courses originated in the 1970s and 1980s and were originally created to provide doctors with simple algorithms to follow in an emergency (Styner, 2006). It was recognized that what mattered in an emergency was not an accurate diagnosis but rather the ability to recognize a life-threatening emergency and take definitive, reflexive action.
These courses were subsequently adapted for paramedic practice and their influence has become almost universal, establishing the ‘ABC’ approach to emergency care. The courses had one thing in common: high flow oxygen was advocated for almost all emergency presentations (Joint Royal College Liasion Committee (JRCALC), 2006).
This has become so established in paramedic practice that it is rare to see a patient delivered to hospital by ambulance without an oxygen mask.
In 2008, the British Thoracic Society convened a multi-disciplinary group of experts to review the use of oxygen in emergency care (O'Driscoll et al, 2008). The impetus for this initiative was increasing concern from respiratory physicians that high flow oxygen had become so widespread in ambulance and hospital emergency practice, and was being applied indiscriminately to almost all patients presenting with an acute condition. Patients with chronic obstructive pulmonary disease (COPD), (in whom the drive to breathe is reliant upon a fall in blood oxygen levels), were coming to harm when given high flow oxygen. This, together with an increasing body of evidence suggesting that high-flow oxygen therapy can cause harm if used inappropriately, led to the comprehensive review of oxygen use in emergency care (O'Driscoll et al, 2008).
The key learning points and drivers for change in paramedic practice are presented in this article. Many paramedics and doctors will initially struggle with the concept of not giving high-flow oxygen to the victim of a heart attack or stroke. However, these, along with other changes to the delivery of oxygen in emergency care, are important and must be introduced into paramedic practice. These changes will ultimately lead to a reduction in adverse outcomes in some patients (particularly those with COPD), and an improvement in resource management.
The key findings of BTS guidelines are summarized below and the reader is encouraged to review the guidelines in more detail (O'Driscoll et al, 2008).
Guideline summary
In general:
The guidelines identify four distinct categories of patient:
Target saturations for each patient should be determined from the presenting complaint, a history of hypercapnic episodes (a high partial pressure of carbon dioxide), or previous interventions with non-invasive ventilation:
Oxygen delivery devices
Non-re-breathe masks are recommended for high-flow oxygen therapy and nasal cannulae for intermediate requirements. 28% or 24% venturi masks should be used for low dose oxygen therapy but may be substituted with low flow nasal cannulae for maintenance of patients with COPD. Tracheostomy masks are also mentioned as a form of therapy for appropriate patients. The oxygen requirements for each of the four patient groups are summarized below:
Category 1: the critically ill patient
Examples include: cardiac arrest, shock, sepsis, near-drowning, severe anaphylaxis, major pulmonary haemorrhage, major head injury and carbon monoxide poisoning.
Initial therapy for these patients should be 15 litres of oxygen per minute delivered via a reservoir mask, with target saturations of 94-98%. The guidelines recognize that advanced interventions (e.g. intubation) will be indicated for many of these critically ill cases. Specifics (e.g. oxygen saturation interpretation in CO poisoning) are provided in the guidelines and the reader is encouraged to review them (O'Driscoll et al, 2008).
Category 2: the seriously ill patient
Examples of patients with serious illnesses in this category include: asthma, pneumonia, lung cancer, postoperative breathlessness, heart failure, pulmonary embolism, pleural effusions, pneumothorax, interstitial lung disease, anaemia, and sickle cell crisis.
Patients with these conditions require moderate levels of oxygen supplementation, which can be delivered through nasal cannulae supplying 2-6 litres per minute, or a face mask supplying 5-10 litres per minute. These patients should have an oxygen saturation target of 94-98%.
If, despite appropriate therapy, the saturations do not reach the desired target, a reservoir mask should be used as second-line therapy. Patients considered at risk of hypercapnic respiratory failure (previous hypercapneic episodes, non-invasive ventilation or alert card details) should have a saturation target of 88-92% and should be reviewed following blood gas analysis.
Category 3: patients with conditions requiring controlled or low dose oxygen therapy
Example conditions include: COPD, acute exacerbations of cystic fibrosis, morbid obesity, chronic neuromuscular conditions, and chest wall deformities.
Patients with these diagnoses require controlled or low-dose therapy. Appropriate oxygen therapy is therefore a 28% venturi mask supplying 4 litres per minute with a target oxygen saturation of 88-92%. This is recommended as patients in this category are at risk of hypercapneic respiratory failure. These patients should be reviewed after arterial blood gas analysis in hospital. If the concentration of oxygen in the blood is found to be normal, the target saturation can be re-adjusted to 94-98%.
If oxygen saturations persist below 88%, the recommended second line therapy is nasal cannulae supplying 2-6 litres per minute or a simple oxygen mask supplying 5 litres per minute. These patients are considered as severely ill and accident and emergency staff should be alerted that they merit senior review.
The guidelines recognize that a diagnosis may not always be obvious. The authors therefore recommend treating any chronic smoker with breathlessness on mild exertion as having COPD for the purposes of management.
Furthermore, paramedics are advised that patients may use terms such as ‘chronic bronchitis,’ and ‘emphysema’ to describe their conditions. These descriptions are synonymous with COPD. Patients may mistakenly refer to their condition as ‘asthma.’ Where doubt exists, paramedics are advised to treat them as COPD patients.
Further oxygen therapy will be determined by the results of blood gas measurements which should be performed and repeated at 3060 minutes after arrival at hospital.
Category 4: patients not requiring oxygen therapy unless hypoxaemic
These are patients in whom oxygen therapy is not routinely required unless the patient is found to be hypoxaemic. These include patients with myocardial infarctions, obstetric and gynaecological emergencies, hyperventilation, poisoning and overdose, paraquat and bleomycin overdose, metabolic and renal problems, and acute and subacute neurological conditions.
Such patients should be monitored closely but there is no evidence to suggest that oxygen therapy is of any benefit. If the patient becomes hypoxaemic, management should be with nasal cannulae supplying 2-6 litres per minute or simple oxygen mask supplying 5 litres per minute. The guidelines recommend giving oxygen until blood arterial gas analysis is available (O'Driscoll et al, 2008).
Conclusion
High flow oxygen therapy should be reserved for the critically or seriously ill and for specific indications. All patients should have an oxygen saturation target which should be estimated from their presenting complaint, previous medical history, or from an ‘alert card,’ provided by their physician.
The authors recognize that these guidelines represent a sea-change in paramedic practice and urge readers to refer to the original guidelines to clarify the specifics of the recommended practice (O'Driscoll et al, 2008).