We generally agree with Dr. Cellarius and Mr. Henry that the main justifications for the different levels of palliative sedation are proportionality and informed consent. For mild levels of distress, mild sedation is appropriate. For more severe distress, heavier sedation (even to the level of unconsciousness) may be needed. With PPS, the level of sedation and the pace of increase are directly related to the severity of otherwise unrelieved suffering. The level of sedation used will be the least amount that can relieve the distress. Although PPS may end with the patient being unresponsive, that is not the intended end point.
We also agree with Dr. Sulmasy and colleagues that the double effect can generally justify PPS (for clinicians who endorse the rule). Relief of suffering is the clinician's primary intent, and although there may be a foreseen risk for hastening death, this is not the clinician's intent (1, 2). However, we do not agree that PPS can only be justified by double-effect reasoning and would not justify it that way ourselves. Intent can distinguish PSU from euthanasia but does not mark the difference between the morally permissible and impermissible, as proponents of double-effect reasoning claim. Death may or may not be intended by patient or clinician in PSU; in some circumstances, intent may be only to relieve suffering and to respect the patient's right to refuse nutrition and hydration, whereas in others intent may be more multilayered (3). How intent applies to PSU is more controversial than how it applies to PPS, but this is less important to us than to Dr. Sulmasy and colleagues in distinguishing between permissible and impermissible actions.
Proportionate palliative sedation is adequate to deal with most but not all intractable end-of-life suffering. We stand by our assertion that PSU will still be needed from the outset in certain compelling cases in which lesser levels of sedation would be insufficient. Consider these real examples:
A terrified patient with advanced oropharyngeal cancer is bleeding from a progressively rupturing carotid artery.
A patient with advanced pulmonary fibrosis is prepared to die rather than be intubated for the third time in 1 month, provided that we promise to aggressively manage his dyspnea. He is now extremely short of breath and agitated, with a carbon dioxide level of 90 mmol/L.
A patient with amyotrophic lateral sclerosis wants to be taken off his mechanical ventilator but is very afraid of suffocation.
For us, these cases are more difficult to justify by using strict double-effect reasoning because death can be both foreseen and to some extent intended by both patient and clinician (4). Stopping at less than total sedation made no sense to the patients, their families, or the clinicians caring for them, and prolonging the patients' extreme suffering by continuing other life-prolonging therapies would have been inappropriate. In each case, the criteria of proportionality were met, informed consent was obtained, and the clinician's primary intent was to relieve the patient's severe suffering; however, to say that assisting these patients to die was completely unintended seems false (3). Rather than relying exclusively on a rule from a particular religious tradition with sometimes unrealistic requirements about intention, it seems better to develop clear guidelines that include ways of responding to some of the most challenging cases.