Questions: A nurse is caring for a client who has a long history of abuse of alcohol and opioid analgesics. When counseling this client about the adverse effects of substance abuse, the nurse should explain that these patterns reduce the oxygenation of his tissues and organs because they cause airway inflammation, direct lung injury, respiratory depression.

The answer is the third one: respiratory depression.

Explanation for each option:

1. Airway inflammation: While substance abuse can lead to airway inflammation, particularly with smoking or inhaling substances, it is not the primary reason for reduced oxygenation of tissues and organs in the context of alcohol and opioid abuse.

2. Direct lung injury: This can occur with certain substances, especially those that are inhaled, but alcohol and opioid analgesics are more commonly associated with systemic effects rather than direct lung injury.

3. Respiratory depression: This is the correct answer. Both alcohol and opioid analgesics can depress the central nervous system, leading to a decreased respiratory rate and depth. This results in reduced oxygen intake and, consequently, lower oxygenation of tissues and organs.

Summary: The nurse should explain that the patterns of alcohol and opioid analgesic abuse reduce the oxygenation of tissues and organs primarily because they cause respiratory depression. This effect leads to a decreased respiratory rate and depth, resulting in insufficient oxygen being delivered to the body's tissues and organs.