A nurse is teaching a client who has sickle cell disease about preventing a sickle cell crisis. Which of the following statements should the nurse make?

Temperature extremes — both cold and heat — are well-established triggers of sickle cell crisis. Cold causes vasoconstriction, which reduces blood flow and promotes sickling of red blood cells. Excessive heat causes dehydration through perspiration, and dehydration is another major trigger because it increases blood viscosity and promotes sickling. Advising clients to avoid temperature extremes directly addresses two physiological mechanisms that precipitate vaso-occlusive crisis. High-impact exercise twice per week is inappropriate because strenuous activity increases oxygen demand, promotes acidosis and dehydration, and can trigger sickling; gentle, moderate activity is preferable. While adequate hydration is indeed protective — and clients should typically drink 2–3 liters of fluid daily — stating only 2 liters per day may actually be insufficient given the increased needs of clients with sickle cell disease who are prone to dehydration; however, the stronger distractor here is that avoiding temperature extremes is a more encompassing and evidence-based recommendation. The influenza vaccine is actually recommended for clients with sickle cell disease because infections are a major crisis trigger; they should receive all recommended vaccinations, including annual influenza vaccine and pneumococcal vaccines, as they are functionally asplenic.