Beta blockers: adverse effects, holds and teaching

A beta-adrenergic blocker protects the heart by blunting the sympathetic drive to it — slowing the rate, easing the force of contraction, lowering the pressure and the heart's demand for oxygen — and its predictable harms are that same action carried too far or reaching receptors beyond the heart, so the nurse anticipates, checks for and teaches every one of them: a heart rate or a blood pressure driven below what the patient tolerates, which is why the apical pulse and the blood pressure are measured before every dose and the dose is held and the prescriber told, rather than given because it is due or omitted in silence, when either falls below the ordered parameter or the patient is dizzy, faint or showing new or worsening heart failure; a heart failure made worse when the drug is begun or increased in a patient who is already decompensating, which is why in heart failure it is started low and raised slowly once the patient is stable, its early fatigue and heaviness tolerated as expected rather than read as proof of harm, and continued through an exacerbation unless the patient is in shock or poorly perfused, because its benefit is counted in survival over the long run rather than in how the patient feels that week; bronchospasm, sharpest with the non-selective agents and never excluded by a cardioselective one, so a new wheeze or breathlessness is reported as the drug's doing rather than treated as a chest infection; a masking of the racing heart, tremor and anxiety that would otherwise warn a diabetic patient of hypoglycemia, while the sweating is spared, so that patient is taught to trust the glucose meter and the sweating over how they feel; a fall in pressure on standing, so the patient is taught to rise slowly; and the fatigue, cold hands and feet, vivid dreams, low mood and sexual dysfunction that are the drug's and not the disease's, reported rather than endured in silence — while the patient is taught above everything else that the tablet is never stopped abruptly, because a heart shielded from adrenaline answers its sudden removal with a rebound of rate and pressure that can bring on angina, infarction or a dangerous rhythm, so a missed dose is not doubled, a supply that is running low is renewed in time, a pressure that has come to normal is the drug working rather than the disease cured, and any change or withdrawal is tapered under the prescriber's direction.