Why is patient selection so important in an OHP?

Appropriate patient selection is critical to help ensure that patients can receive safe care in OHPs. The Out-of-Hospital Premises Inspection Program has historically seen a number of adverse events that result from inappropriate patient selection. The Patient Selection Standard requires physicians to classify patients, prior to a procedure where general or regional anesthesia or sedation will be used, using the American Society of Anesthesiologists’ Physical Status Classification System and only perform procedures on patients who are classified as ASA I, ASA II or, in some circumstances, ASA III. Generally, ASA IV patients are unsuitable to be treated in an OHP.

The process of determining suitability of a patient to undergo a procedure in an OHP involves the complex interplay of several factors, and there can be a significant difference in the way physicians classify patients and determine which ASA III patients they consider appropriate to treat in an OHP. The Patient Selection Standard and this Advice are intended to help physicians appropriately exercise professional judgment in relation to these patients.

How do I determine which ASA classification a patient should have?

In determining the appropriate ASA classification for a patient there are a number of factors that need to be considered. The table below¹ outlines some examples of conditions or diseases that would influence the determination of a patient’s ASA classification.

ASA Classification	Definition	Adult Examples
I	A normal healthy patient	Healthy, non-smoking, no or minimal alcohol use
II	A patient with mild systemic disease	Mild diseases only without substantive functional limitations. Examples include (but not limited to): current smoker, well-controlled diabetes mellitus or hypertension, mild lung disease
III	A patient with severe systemic disease	Substantive functional limitations; 1 or more moderate to severe diseases. Examples include (but not limited to): poorly controlled diabetes mellitus or hypertension, chronic obstructive pulmonary disease, transient ischemic attack, coronary artery disease/stents

What are key considerations when determining whether it’s appropriate to perform a procedure on a patient in an OHP?

Several comorbid conditions have been demonstrated to have an effect on patient outcomes after procedures in an OHP type setting and therefore need to be carefully considered in patient selection. Independent factors identified by a majority of studies include:

• advanced age
• morbid obesity
• obstructive sleep apnea
• cardiac disease
• chronic obstructive pulmonary disease
• diabetes mellitus
• end-stage renal disease
• transient ischemic attack/stroke,
• chronic opioid use or opioid use disorder, and
• malignant hyperthermia.²

While any one comorbid condition on its own may not make a patient unsuitable for care in an OHP, physicians will need to carefully consider how any of these co-morbidities could put a patient at higher risk of a poor outcome in an OHP.

Generally, patients would be unsuitable for a procedure in an OHP where they:

• have unstable or poorly managed chronic illnesses;
• have unmanaged alcohol or substance use disorders; or
• are undergoing active immunosuppressant cancer treatment.

Physicians are required to exercise their professional judgement when determining the appropriateness of performing procedures on patients in an OHP, and where they are unsure or where the patient is classified as ASA III and will be receiving more than mild sedation, are required to consult with the physician administering the anesthesia or sedation well in advance of the procedure.

Why do physicians need to discuss ASA III cases well in advance?

The Patient Selection Standard does allow room for professional judgement when it comes to determining which ASA III patients may be appropriate to have a procedure in an OHP. However, it is important that professional judgment in these circumstances be exercised in a considered way. Requiring that discussions take place between the physician who will be performing the procedure and the physician administering the anesthesia or sedation will help to ensure that both physicians have thought through the potential complicating factors of performing a procedure on the patient in the OHP setting, and both agree that it is appropriate to do so in the circumstances. It is important for discussions to take place in advance in order to manage patient expectations and avoid any pressure to perform a procedure that has been scheduled where it might not be appropriate.

Endnotes

^1. Modified from Rajan, N, Rosero E, and Joshi, G 2021, ‘Patient Selection for Adult Ambulatory Surgery: A Narrative Review’, International Anesthesia Research Society, vol. 133, no. 6, pp 1415-1430. Please see this article for more information.

^2. Rajan, N, Rosero E, and Joshi, G 2021, ‘Patient Selection for Adult Ambulatory Surgery: A Narrative Review’, International Anesthesia Research Society, vol. 133, no. 6, pp 1415-1430.