Which of the following complications can arise from straining during defecation in older adults?

Straining during defecation can lead to dysrhythmias in older adults primarily due to the physiological response that occurs during this process. When an individual strains, especially if they are holding their breath, it can result in a sudden increase in intrathoracic pressure. This change can temporarily alter heart rate and rhythm due to the effects on the vagus nerve, which plays a critical role in heart function. This can lead to arrhythmias, particularly in those who may already have pre-existing heart conditions or are taking medications that affect heart rhythm.

Understanding the other options provides additional context. Hypertension can occur as a temporary response due to straining but is not considered a direct complication in the same way dysrhythmias are. Hypoglycemia tends to relate to low blood sugar levels and is not typically associated with the act of straining during bowel movements. Dehydration might result from inadequate fluid intake or other health issues but does not directly result from the act of straining to defecate. Therefore, dysrhythmias are recognized as a specific risk in older adults who may already have underlying cardiac vulnerability exacerbated by the strain of defecation.