Introduction
Hypertension is characterized by markedly elevated blood pressure. It is commonly present in association with diabetes mellitus. In the United States alone, 23.6 million adults are diabetics. Most of these patients have hypertension as comorbidity (American Diabetes Association, 2008a, p. 1). According to Geiss, Herman, and Smith, “Hypertension is a common comorbidity in these patients…it is 1.5 to three times more common in patients with diabetes than in those who do not have the disease” (1995, p. 239). A large proportion of patients with diabetes dies from cardiovascular and cerebrovascular disease with hypertension being described as a significant risk factor for these microvascular complications (Barst, 2008, p. 25). Evidence suggests that a tight control of blood pressure in known diabetics and hypertensive patients causes a reduction in morbidity and mortality associated with the combination of these diseases (Barst, 2008, p. 25). To achieve this goal, it is necessary that nurses master the pharmacological treatments, the effects, and contraindications of each of the treatments. This essay discusses the pathophysiology of hypertension elderly diabetic patients, pharmacological principles in its management, and the general nursing care.
Discussion
Pathophysiology
Essential hypertension is the main type of hypertension found in the elderly. However, the pathophysiology is different from the essential hypertension that would be found in younger patients. According to Barst, “isolated systolic hypertension (systolic blood pressure 140 mmHg or greater and diastolic blood pressure below 90 mmHg) increases in frequency with age” (2008, p. 2). In the elderly, the main pathophysiology is the increase in the peripheral resistance in the blood vessels, decreased cardiac output, reduction of compliance in middle-sized and large arteries, and reduced baroreceptor function (Barst, 2008, p. 13). There is also reduction in blood flow to essential organs such as the kidney, the brain, and a dysfunction in the auto regulation in these organs (Barst, 2008, p. 13).
In animals and human beings, the blood pressure is a product of cardiac output and the total peripheral resistance that is provided by the blood vessels (Barst, 2008, p. 7). Maintenance of a normal blood pressure is therefore dependent on the balance between these two factors in individuals (Barst, 2008, p. 8). In hypertensive elderly patients, cardiac output is normal in most cases with the main reduction being on the total peripheral resistance (Barst, 2008, p. 8). The peripheral resistance is determined by the arterioles with smooth muscles on their walls since they are able to constrict and dilate based on the control that is needed. Some studies have suggested normal peripheral resistance characterizes early hypertension with cardiac output being significantly raised (Chobanian et al., 2003, p. 2570). Other studies have suggested that, as individuals’ age progresses, the endothelium of blood vessels undergoes a series of changes, which bring about endothelial dysfunction that may be associated with essential hypertension (Rosendorff et al., 2007, p. 2778). Hypertension often complicates diabetes mellitus in the elderly with the reverse being true (Rosendorff et al., 2007, p. 2778). They may also arise simultaneously.
Review of pharmacological agents in treatment
The treatment of hypertension in diabetics and elderly patients is similar to other hypertensive patients in medication though the types used and the doses as well as the care accorded are different. Angiotensin converting enzyme (ACE) inhibitors “prevent or delay micro and macro vascular complications of diabetes, and are recommended as first-line antihypertensive agents in patients with diabetes” (Katzung, Masters, & Trevor, 2009, p. 177). They are also described as “delaying diabetic kidney disease with their use being more effective than other medications in delaying renal failure” (Lewie et al., 2001, p. 858). Many organizations and medical practitioners propose hypertension treatment with ACE inhibitors in patients with diabetes, and in any stage of renal failure (Brenner et al., 2001, p. 869). Studies confirm a better outcome in treatment of hypertension with ACE inhibitors with diabetic associated nephropathy (Brenner et al., 2001, p. 869).
Another group of drugs that are of use in the treatment of hypertension in elderly diabetics is angiotensin receptor blockers. As the group discussed above, angiotensin receptor blockers alter the progression of renal disease in patients with diabetes (American Diabetes Association, 2008b). Besides, being protective, they delay the onset of renal failure in patients with “type 2 diabetes, hypertension, and macro albuminuria” (Lewie et al., 2001, p. 858: Brenner et al., 2001, p. 869). Some studies have found a reduced incidence of heart failure in patients under treatment for hypertension using these drugs (Brenner et al., 2001, p. 869). In fact, they may be used as a replacement for the ACE inhibitors. However, due to their relatively high cost and equal no added advantage over ACE inhibitors, they are used in patients not tolerating the ACE inhibitors (Brenner et al., 2001, p. 871).
Diuretics are necessary drug lines in the treatment of hypertension in diabetics. The most preferred diuretics are thiazide diuretics, which are used either as monotherapy or in combination regimens (Whelton et al., 2005, p. 1403). In one of the studies done on the use of thiazide diuretics in hypertension treatment, clorothiazide was found to be associated with lower incidences of heart failure in hypertensive patients with diabetes and hypertension (Whelton et al., 2005, p. 1406). Some of the effects that are of concern with the use of thiazide diuretics include metabolic alterations that they produce. According to Luna and Feinglos, with “the use of thiazide diuretics, higher dosages have been linked to elevations in cholesterol and triglyceride levels and loss of glycemic control though these dosages are not routinely used in clinical practice” (2001, p. 286). They have been found to reduce the risks of cardiovascular events in these patients and “the risk of clinically significant alterations in glucose metabolism is minimal” (Luna, & Feinglos, 2001, p. 286).
Beta-blockers are another class of drugs utilized in the management of hypertensive patients with diabetes mellitus (Chobanian et al., 2003, p.2570). They are used in combination with the agents listed above especially “when combined with ACE inhibitors in patients with a baseline pulse rate greater than 84 beats per minute” (Bakris et al., 2000, p. 652). Studies compared their ability to reduce the incidence of cardiovascular complications to that of ACE inhibitors and ARBs (Bakris et al., 2000, p. 652). Rosendorff et al., state, “Beta blockers are an important component of antihypertensive regimens in patients who have diabetes, CAD, and stable angina” (2007, p. 2778). These drugs have been used cautiously in the past in patients with diabetes mellitus. The reason for this as Rosendorff et al. states is “because of concern that hypoglycemic symptoms could be masked or that recovery from hypoglycemia could be blunted” (2007, p. 2778). Studies such as the one done by Chobanian et al. have revealed, “no difference in the rates of minor or major hypoglycemic episodes in patients treated with atenolol compared with those treated with captopril (Capoten)” (2003, p. 2570). They can be safely used in these patients. Insulin sensitivity and glucose tolerance are also altered with the use of these drugs though the effects are of little clinical significance (Chobanian et al., 2003, p. 2570).
Calcium channel blockers are another group of drugs used to manage hypertension in the patients. As Tuomilehto et al. state, “Dihydropyridine calcium channel blockers (CCBs) reduce cardiovascular events in patients with diabetes and hypertension though they may be inferior to other agents in some cardiovascular outcomes” (1999, p. 680). Calcium channel blockers may be less useful in the treatment of hypertension in diabetics. According to Tuomilehto et al., “they should be reserved for patients who cannot tolerate preferred agents or those who need additional agents to achieve target blood pressure” (1999, p. 680). The above drugs have been demonstrated to have an effect in the treatment of hypertension in diabetic patients. Nurses need to have knowledge on their use and effect, as well as the adverse effects.
Pharmacological management
As stated above, most of the patients under management for hypertension in diabetes require a combination therapy to achieve effectiveness and safety. The use of ACE inhibitors, Angiotensin receptor blockers, or calcium channel blockers is known to increase insulin sensitivity in diabetics. They should be used as first choice antihypertensive in the elderly with diabetes and hypertension (Harvey, 2011, p. 188). Although α – adrenergic blockers are also observed to increase insulin sensitivity in diabetics, Katzung, Masters, and Trevor, state, “α -blockers should be used cautiously because they frequently induce postural hypotension” (2009, p. 177). It is the role of the nurse to monitor blood pressure when using these drugs and to ensure that they keep an open eye to the complication. Care should also be taken when using α –blockers because they are observed to “mask or prolong hypoglycemic symptoms” (Katzung, Masters, & Trevor, 2009, p. 179).
In the elderly patients with hypertension and pre-existing diabetes mellitus, the use of antihypertensive drugs with different mechanisms of action is advisable (Katzung, Masters, & Trevor, 2009, p. 179). Since more than one of the agents stated above is required in treatment, the use of combinations or fixed dose combinations should be explored. Many fixed dose combinations are currently being marketed under different brand names. This strategy is convenient for the elderly diabetics who may be taking a large number of medications for other pre-existing conditions (Harvey, 2011, p. 188). ACE inhibitors are recommended as first therapy where lifestyle modification has been unsuccessful. The targeted blood pressure levels are not achieved. An ARB may be substituted in place of an ACE inhibitor where the patient cannot tolerate them (Harvey, 2011, p. 188). A diuretic such as a thiazide diuretic is normally added when significant reduction in blood pressure is not attained. Loop diuretics may be used in the place of thiazide diuretics where a patient has pre-existing renal insufficiency (Harvey, 2011, p. 188). The third-line agents in these patients include calcium channel blockers or beta-blockers (Harvey, 2011, p. 188).
Nursing implications
In the nursing care of a patient receiving pharmacotherapy for hypertension and diabetes, a number of precautions are necessary. The nursing staff should be well aware of the effects of the pharmacotherapy, as well as the expected outcomes in the patient. To monitor the efficacy of the drugs being given for the hypertension, it is important that blood pressure be monitored regularly (Tabloski, 2010, p. 38). This effort will also provide clinicians with the choice of drugs to use and or whether to proceed to second and third-line drugs. In the acute management of the patient, the urinary output should be monitored to make sure that the patient is not in renal failure (Tabloski, 2010, p. 39). This step may be done in some patients through catheterization. Some of the patients may also present with symptoms of the toxicity of the drugs. The nurse needs to anticipate them for quicker response. Thiazide diuretics may cause a dry cough in such patients. The nursing staff may interpret it as a pathological condition (Tabloski, 2010, p. 42). Treatment may therefore be started based on the misdiagnosis. It may be of no help to the patient. During the treatment and care for hypertensive with diabetes mellitus, it is important for the nurse to monitor the use of the medication. Patients must be assessed to ensure that they are receiving the right medication, the medication is effective, safe, and the patient is adhering to treatment (Tabloski, 2010, p. 38). To achieve this goal, the nurse should develop a pharmacotherapy care plan (Tabloski, 2010, p. 42). According to Tabloski, “the patient’s care plan should be constructed with the patient’s involvement, and in a multidisciplinary fashion, developed and altered in a cooperative way by all who are involved with the patient’s care” (2010, p. 38). The care plan should include current drug regimen, drug therapy problems, therapy goals, desired endpoints, therapeutic recommendations, rationale, Therapeutic alternatives, monitoring and patient education (Tabloski, 2010, p. 38).
Pharmacodynamics properties and actual/potential effects on the patient
Diuretics may be of use in the management of hypertensive patients with diabetes mellitus. However, their use is associated with impaired glucose tolerance, which may complicate the treatment of the diabetes (Harvey, 2011, p. 188). It is therefore necessary that the nursing staff that is charged with the duty of monitoring patients on diuretics anticipate the effects and act on them when they occur. Methyldopa is frequently used in the treatment of hypertension in the elderly with persistent mental lassitude and impaired concentration being observed in these patients (Katzung, Masters, & Trevor, 2009, p. 175). Before instituting the medication, the nurse should explain to the patient about these side effects in an attempt to provide alternatives to the drug.
Clonidine is another frequent used drug with dry mouth and sedation being frequently experienced (Harvey, 2011, p. 188). The drug is effective in lowering the blood pressure with the side effects accompanying the positive actions (Katzung, Masters, & Trevor, 2009, p. 179). Nurses should therefore expect the side effects in patients under treatment with the drug to ensure the patient is well informed to prevent non-adherence. Concerning the adrenergic neuron blockers mentioned above, Guanethidine is frequently used in this class (Katzung, Masters, & Trevor, 2009, p. 179). According to Harvey, “therapeutic use of Guanethidine is associated with symptomatic postural hypotension and hypotension following exercise particularly when the drug is given in high doses, and may produce dangerously reduced brain flow and overt shock” (2011, p. 188). The drug has however been used as an outpatient drug for patients with very high blood pressure.
Propranolol is also preferred in the treatment of hypertension in elderly patients with diabetes mellitus with it being found to have an added effect on diabetes (Katzung, Masters, & Trevor, 2009, p. 179). However, the discontinuation of the drug causes withdrawal syndrome “manifested by nervousness, tachycardia, increased angina intensity, and increased blood pressure” (Katzung, Masters, & Trevor, 2009, p. 179). Withdrawal syndrome should therefore be monitored in patients no longer needing the drug. The nurse should anticipate these effects. The most widely used vasodilator in the treatment of hypertension in the elderly according to Harvey is Hydralazine (2011, p. 188). It has been associated with side effects such as headache, nausea, anorexia, palpitations, sweating and flushing (Katzung, Masters, & Trevor, 2009, p. 175). Patients should be advised to report these side effects during treatment with the drug. Proper adjustment to the dosage should be made in those who experience them.
In the treatment of diabetic patients with ACE inhibitors, it is important to monitor the electrolytes, as the drugs have been known to cause hypokalemia in these patients (Katzung, Masters, & Trevor, 2009, p. 171). This case may be monitored through assays of the levels of the electrolytes in the blood. Therefore, any alterations should be corrected with withdrawal of the drugs where the hypokalemia is severe (Katzung, Masters, & Trevor, 2009, p. 169). Although the use of angiotensin receptor blockers is associated with cough and angioedema seen in ACE inhibitors toxicity, these side effects are less common with the drugs (Katzung, Masters, & Trevor, 2009, p. 179).
Conclusion
In conclusion, the treatment of hypertension in elderly patients with diabetes mellitus offers a challenge to nurses due to the susceptibility of this age group to the side effects of the drugs. Management of the patients offers a challenge due to the type of hypertension found in the patients, which is mainly essential hypertension. Some of the pharmacological substances discussed to be of use in the treatment of hypertension in elderly diabetic patients include angiotensin converting enzyme inhibitors, angiotensin receptor blockers, diuretics, calcium channel blockers, and adrenergic blocking drugs. The effects and unwanted effects associated with these drugs have been evaluated followed by a discussion of the role played by nurses in the treatment.
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