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Psychiatric symptoms are often the cause of, or the effect of many toxicologic-presentations. Suicide attempts and aggressive behaviors are commonly associated with toxicity and can be uniquely difficult to assess and manage in the emergency department. Patient factors, clinician bias, and a lack of coordination of care exacerbate the difficulties and make evaluating and treating patients with psychiatric symptoms uniquely challenging in the medical setting. Patients are unable or unwilling to communicate adequately. They are frequently disorganized, psychotic, and engaged in self-injurious and/or dangerous behaviors. Mental illness, personality disorders, delirium, intoxication and withdrawal are frequently the underlying etiology of these behaviors and can interfere with treatment. The combative, threatening, and/or violent patient requires special consideration as the safety of the patient and staff is imminently jeopardized. The individual’s medical condition and/or behavior can be life threatening, disruptive, and/or destructive. Patient behaviors are viewed dichotomously as deliberate, totally “out of control,” and irrational. The truth is more complex, with some aspects occurring within the awareness and control of the patient and other aspects either unknown, out of the patient’s control, and/or overwhelming to the patient. Coordination with and availability of psychiatric care is difficult and inaccessible.

Substances of abuse, overdose, and toxicity or adverse effects of psychiatric medications are the most obvious commonalities between the fields of psychiatry and toxicology. However, psychiatric symptoms overshadow other toxic or metabolic conditions and are confused for primary mental illnesses. In addition, the adverse effects or toxicity of xenobiotics mimics various symptoms of mental illness. Given the increased rates of suicide attempts and substance abuse among people with severe mental illness, distinguishing cause and effect is complex.

This chapter will review some of the special considerations that should be recognized when dealing with the overlap between psychiatry and ­toxicology. The chapter will start with an overview of the capacity assessment and its formal components. Then there is a discussion of the components of the medical evaluation of psychiatric patients for admission to a psychiatric facility. The third section is devoted to suicide and the suicidal or self-injurious patient. And finally substance use disorders are addressed. Principles of workplace violence and the violent patient will we addressed in Special Considerations: SC4.


“Decision-making capacity is the ability to understand relevant information and to appreciate the reasonably foreseeable consequences of the decision.”3 Every consent form requires documentation of some aspects of a capacity assessment. Physicians are legally and ethically obligated to obtain informed consent for treatment and procedures. The initial presumption when evaluating capacity is that all people have decisional capacity.2 Depriving a patient of his or her decision-making rights is a serious infringement on his or her liberties that has legal and ethical implications. Yet, only a patient with capacity can legally consent to medical treatment. Allowing a patient without capacity to consent to medical treatment is also problematic and ...

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