Capacity: What do we need know about patients before we can do what they tell us to do?
A person may lack capacity to decide certain things and have capacity to do others. A person may be lack the capacity to decide sophisticated financial affairs, but have the capacity to make medical decisions for themselves.
The magnitude of the risk involved and the medical intervention contemplated is central to assessments of capacity. A decision to install a PICC line has a different level of risk than extubating (withdrawal of care) in a patient who clearly requires assistance in breathing. So, we can accept a consent to a PICC line but not necessarily to extubate.
Levels of capacity vary overtime. A person may lack capacity, e.g., due to levels of sedation or the effect of sepsis on cognitive function. We should then determine if we can wait for the patient to recover to a satisfactory level of capacity to make a decision for herself.
A person who signs an advance health directive five years earlier does not mean that we are restricted from asking what they want to do in a specific situation, presently. An Advanced Health Directive is made in anticipation of a time when decisions cannot be made. Yet, a person may make medical decision at anytime so long as they have the capacity to do so, and therefore should not be made to feel that they must adhere to earlier directives. A patient’s understanding and ability to reason with respect to medical decisions may in fact increase overtime as the patient’s comprehension and experience of their medical condition improves.
In short, a patient must be able to understand, deliberate, and communicate their choice. The first question is what approach should we take to assess this capacity and secondly what gauge can we apply to determine the amount or degree of understanding required to make the specific decision at hand.
There are two subjective standards that need to be evaluated, and are mutually dependent: how, and in what way information is provided; how, and in what way information is understood, deliberated upon and the voluntariness (or undue influence) of the decision.
