The effect of increased salt intake on blood pressure of chimpanzees

A colony of 26 chimpanzees given a fruit and vegetable diet of very low Na and high K intake were maintained in long-standing, socially stable small groups for three years. Half of them had salt added progressively to their diet during 20 months. This addition of salt within the human dietetic range caused a highly significant rise in systolic, mean and diastolic blood pressure. The change reversed completely by six months after cessation of salt. The effect of salt differed between chimpanzees, some having a large blood pressure rise and others small or no rise. These results in the species phylogenetically closest to humans bear directly on causation of human hypertension, particularly in relation to migration of preliterate people, with low Na diet, to a Western urban lifestyle with increased salt intake. The hedonic liking for salt and avid ingestion was apt during human prehistory involving hunter-gatherer-scavenger existence in the interior of continents with a scarcity of salt, but is maladaptive in urban technological life with salt cheap and freely available.

Spontaneous systemic hypertension in 24 cats

Twenty-four cats with spontaneous systemic hypertension were retrospectively studied. Blood pressure (BP) was measured indirectly by the Doppler technique in 17 cats (mean systolic 219.4 +/- 43.2 mm Hg) and directly by femoral arterial puncture in 15 cats (mean systolic/diastolic 233.2 +/- 40.9/148.1 +/- 28.7 mm Hg). All cats had bilateral retinal hemorrhages and/or detachments. Twenty cats presented because of blindness. Other presenting signs included polyuria/polydipsia, weight loss, neurological signs, and/or epistaxis. Diagnostic tests were performed to determine the presence and the cause of any secondary organ damage. Common findings included retinal hemorrhages/detachments, low-grade systolic murmurs, cardiomegaly with left ventricular hypertrophy (LVH), small kidneys, mild azotemia, and urine specific gravity < or = 1.020. Only 3 cats had hyperthyroidism. One cat was transiently diabetic. Necropsies on 2 cats with neurological signs showed nephrosclerosis, arteriosclerosis, and multifocal cerebral hemorrhages. Twenty cats were treated with diuretics, beta-adrenergic antagonists, and/or an angiotensin converting enzyme (ACE) inhibitor. One cat was treated with methimazole only, and 1 was treated with insulin transiently. The median survival of the 24 cats was 18 months. Response to therapy did not appear to have an impact on survival time.

Hypertension in cats with chronic renal failure or hyperthyroidism

The Doppler ultrasonic recording technique was used to measure systolic and diastolic blood pressures indirectly in 28 cats with naturally occurring renal failure, 39 cats with hyperthyroidism, and 33 clinically normal cats. The mean systolic and diastolic blood pressures in the normal cats were 118.4 +/- 10.6 mm Hg and 83.8 +/- 12.2 mm Hg, respectively. In the cats with chronic renal failure, both the systolic (146.6 +/- 25.4 mm Hg) and diastolic (96.6 +/- 15.2 mm Hg) blood pressures were significantly higher (P less than 0.0001 and P less than 0.01, respectively) than in the normal cats. Elevations in systolic and/or diastolic blood pressure were recorded in 17 (61%) of the 28 cats with chronic renal failure. In the 39 untreated hyperthyroid cats, both the mean systolic (167.9 +/- 28.9 mm Hg) and diastolic (111.6 +/- 21.5 mm Hg) pressures also were significantly higher (P less than 0.0001) than normal. Increased systolic and/or diastolic blood pressure was recorded in 34 (87%) of the 39 hyperthyroid cats. In seven cats with hyperthyroidism that were reevaluated two to four months after successful treatment of the hyperthyroid state, there was a significant fall in mean systolic pressure (P less than 0.05) from a pretreatment value of 159.5 +/- 15.4 mm Hg to a posttreatment value of 132.0 +/- 1.62 mm Hg. Overall, the results of this study indicate that mild to moderate hypertension is common in cats with chronic renal failure and in cats with untreated hyperthyroidism. In addition, the hypertension appears to be reversible following successful treatment of the hyperthyroid state.

Ocular lesions associated with systemic hypertension in cats: 69 cases (1985-1998)

OBJECTIVE

To characterize clinical and clinicopathologic findings, response to treatment, and causes of systemic hypertension in cats with hypertensive retinopathy.

DESIGN

Retrospective study.

ANIMALS

69 cats with hypertensive retinopathy.

PROCEDURE

Medical records from cats with systemic hypertension and hypertensive retinopathy were reviewed.

RESULTS

Most cats (68.1%) were referred because of vision loss; retinal detachment, hemorrhage, edema, and degeneration were common findings. Cardiac abnormalities were detected in 37 cats, and neurologic signs were detected in 20 cats. Hypertension was diagnosed concurrently with chronic renal failure (n = 22), hyperthyroidism (5), diabetes mellitus (2), and hyperaldosteronism (1). A clearly identifiable cause for hypertension was not detected in 38 cats; 26 of these cats had mild azotemia, and 12 did not have renal abnormalities. Amlodipine decreased blood pressure in 31 of 32 cats and improved ocular signs in 18 of 26 cats.

CONCLUSIONS AND CLINICAL RELEVANCE

Retinal lesions, caused predominantly by choroidal injury, are common in cats with hypertension. Primary hypertension in cats may be more common than currently recognized. Hypertension should be considered in older cats with acute onset of blindness; retinal edema, hemorrhage, or detachment; cardiac disease; or neurologic abnormalities. Cats with hypertension-induced ocular disease should be evaluated for renal failure, hyperthyroidism, diabetes mellitus, and cardiac abnormalities. Blood pressure measurements and funduscopic evaluations should be performed routinely in cats at risk for hypertension (preexisting renal disease, hyperthyroidism, and age > 10 years). Amlodipine is an effective antihypertensive agent in cats.

Association between initial systolic blood pressure and risk of developing a uremic crisis or of dying in dogs with chronic renal failure

OBJECTIVE

To determine whether high systolic blood pressure (SBP) at the time of initial diagnosis of chronic renal failure in dogs was associated with increased risk of uremic crisis, risk of dying, or rate of decline in renal function.

DESIGN

Prospective cohort study.

ANIMALS

45 dogs with spontaneous chronic renal failure.

PROCEDURE

Dogs were assigned to 1 of 3 groups on the basis of initial SBP (high, intermediate, low); Kaplan-Meier and Cox proportional hazards methods were used to estimate the association between SBP and development of a uremic crisis and death. The reciprocal of serum creatinine concentration was used as an estimate of renal function.

RESULTS

Dogs in the high SBP group were more likely to develop a uremic crisis and to die than were dogs in the other groups, and the risks of developing a uremic crisis and of dying increased significantly as SBP increased. A greater decrease in renal function was observed in dogs in the high SBP group. Retinopathy and hypertensive encephalopathy were detected in 3 of 14 dogs with SBP > or = 180 mm Hg. Systolic blood pressure remained high in 10 of 11 dogs treated with antihypertensive drugs.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested that initial high SBP in dogs with chronic renal failure was associated with increased risk of developing a uremic crisis and of dying. Further studies are required to determine whether there is a cause-and-effect relationship between high SBP and progressive renal injury and to identify the risks and benefits of antihypertensive drug treatment.

Routine health screening: findings in apparently healthy middle-aged and old cats

STUDY RATIONALE

Veterinary practitioners often perform geriatric health screening in cats. Unfortunately, scientific information regarding clinical and laboratory abnormalities and normal blood pressure values in elderly cats is scarce. This prospective study evaluated routine health screening tests in apparently healthy middle-aged and old cats.

PROTOCOL

One hundred cats of 6 years and older underwent blood pressure measurement, physical examination, blood and urine analysis, indirect fundoscopy and bilateral Schirmer tear tests.

FINDINGS

Mean systolic blood pressure (SBP) was 133.6 ± 21.5 mmHg. Increased SBP (>160 mmHg) was observed in eight cats, submandibular lymphadenopathy in 32, gingivitis in 72, heart murmur in 11, thyroid goitre in 20, increased creatinine in 29, hyperglycaemia in 25, increased total thyroxine in three, feline immunodeficiency virus positivity in 14, crystalluria in 41, borderline proteinuria in 25 and overt proteinuria in two. Mean tear production was very similar for both eyes and none of the cats had ocular lesions secondary to hypertension.

CLINICAL SIGNIFICANCE

Old cats (>10 years) had significantly higher SBP, heart rate, murmur frequency, thrombocyte count, urine protein:creatinine ratio and serum urea and bilirubin concentrations, and significantly lower body condition score, haematocrit, albumin and total calcium concentrations than middle-aged cats (6-10 years). The common occurrence of physical examination and laboratory abnormalities in apparently healthy old cats underlines the need for regular health checks and the development of age-dependent laboratory reference intervals.

Indirect systolic and mean blood pressure determination by a new tail cuff method in spontaneously hypertensive rats

A new tail cuff method for determining systolic and mean blood pressure in rats was developed based on photoelectric detection of tail arterial blood flow and pulsatile volume oscillation. Indirect systolic and mean blood pressure measured by this method correlated well with direct systolic and mean blood pressures recorded by a transducer and polygraph after carotid artery cannulation in stroke-resistant spontaneously hypertensive rats (SHR), stroke-prone SHR and normotensive Wistar Kyoto rats. Blood pressures were sharply, and transiently raised for about 1 min when rats were picked up by an investigator to be placed in a hot box or immobilized in a restrainer for measuring blood pressure. Therefore, blood pressures should be measured at least 1 min after the rats are put in a restrainer. This new tail cuff method for measuring blood pressure provides reliable mean blood pressure readings in conscious rats.

Feline hypertension: clinical findings and response to antihypertensive treatment in 30 cases

Systolic hypertension was diagnosed in 30 cats. At diagnosis, 16 of those were found to be in chronic renal failure only, while five were azotaemic and either receiving treatment for hyperthyroidism (four cases) or were untreated hyperthyroid cases (one case). Two cases were untreated hyperthyroid cases with no evidence of azotaemia and the remaining seven cases had no definitive diagnosis of the underlying cause of their hypertension. The successful treatment used for the majority of cases was amlodipine, which lowered systolic blood pressure from 202.5+/-16.8 to 153.2+/-21.6 mmHg (mean+/-SD; n=29) within the first 50 days. Each case was followed for at least three months, or to the end of its natural life, and each cat was re-examined every six to eight weeks. Systolic blood pressure was kept below a target value of 165 mmHg in 58 per cent of cases treated for three months or longer. At the time of writing, 19 of the cases had died or been euthanased with a median treatment time of 203 days, one case was lost to follow-up and 10 cases were still alive, nine of which had been treated for six months or more. Amlodipine can be used for long-term control of feline systemic hypertension.

ISFM Consensus Guidelines on the Diagnosis and Management of Hypertension in Cats

Practical relevance: Feline hypertension is a common disease in older cats that is frequently diagnosed in association with other diseases such as chronic kidney disease and hyperthyroidism (so-called secondary hypertension), although some cases of apparent primary hypertension are also reported. The clinical consequences of hypertension can be severe, related to 'target organ damage' (eye, heart and vasculature, brain and kidneys), and early diagnosis followed by appropriate therapeutic management should help reduce the morbidity associated with this condition. Clinical challenges: Despite being a common disease, routine blood pressure (BP) monitoring is generally performed infrequently, probably leading to underdiagnosis of feline hypertension in clinical practice. There is a need to: (i) ensure BP is measured as accurately as possible with a reproducible technique; (ii) identify and monitor patients at risk of developing hypertension; (iii) establish appropriate criteria for therapeutic intervention; and (iv) establish appropriate therapeutic targets. Based on current data, amlodipine besylate is the treatment of choice to manage feline hypertension and is effective in the majority of cats, but the dose needed to successfully manage hypertension varies between individuals. Some cats require long-term adjuvant therapy and, occasionally, additional therapy is necessary for emergency management of hypertensive crises. Evidence base: These Guidelines from the International Society of Feline Medicine (ISFM) are based on a comprehensive review of the currently available literature, and are aimed at providing practical recommendations to address the challenges of feline hypertension for veterinarians. There are many areas where more data is required which, in the future, will serve to confirm or modify some of the recommendations in these Guidelines.

Management of hypertension controls postoperative neurologic disorders after renal transplantation in cats

OBJECTIVES

To determine the prevalence and describe the management of hypertension and central nervous system (CNS) complications after renal transplantation in cats. We also compared the prevalence of CNS complications between cats monitored and treated for postoperative hypertension and a previously described, historical control group of cats not monitored or treated for postoperative hypertension.

STUDY DESIGN

Retrospective clinical study.

ANIMALS OR SAMPLE POPULATION

A total of 34 client-owned cats that received renal allografts for the treatment of end-stage renal failure.

METHODS

Medical records were reviewed. Data obtained included preoperative and postoperative systolic blood pressures, antihypertensive therapy, response to treatment, neurologic signs, and clinical outcome. The results were compared with a historical control group of feline renal allograft recipients that were neither monitored nor treated for postoperative hypertension.

RESULTS

Severe postoperative hypertension occurred in 21 of 34 of cats. Hypertension was treated in all 21 cats with subcutaneously administered hydralazine which reduced systolic blood pressure to less than 170 mm Hg in 15 minutes in 20 of 21 cats; hydralazine produced hypotension in one cat and failed to control hypertension in 1 cat. After transplantation, seizures were observed in one cat and other neurologic complications (stupor, ataxia, and central blindness) were observed in three cats. The prevalence of seizures and neurologic complication-related deaths after transplantation was significantly reduced with treatment of postoperative hypertension.

CONCLUSIONS AND CLINICAL RELEVANCE

Hypertension is a major contributing factor to postoperative seizure activity after renal transplantation in cats; treatment of hypertension reduces the frequency of neurologic complications.

Amlodipine: a randomized, blinded clinical trial in 9 cats with systemic hypertension

The efficacy of amlodipine (AML) was tested in hypertensive cats in a placebo-controlled, randomized, blinded clinical trial. Five cats were randomized to receive 0.625 mg AML once daily and 4 cats to receive placebo (PLA) once daily. The average systolic blood pressure (SBP) recorded by the Doppler method on day 0 was 212 +/- 21 mm Hg in the AML group and 216 +/- 32 mm Hg in the PLA group. On day 7, the cats receiving AML had a significantly lower average daily SBP (160 +/- 30 mm Hg) but SBP in the PLA group was unchanged (207 +/- 31 mm Hg). On day 7, all cats receiving PLA and one cat receiving AML were crossed over to the other group because of inadequate response. Blood pressure did not decrease adequately in 3 cats by day 14 (7 days of PLA and 7 days AML) and the treatment code was broken. Each of these cats was subsequently administered 1.25 mg AML daily. Cats requiring 1.25 mg AML once daily (6.1 kg +/- 0.7 kg) weighed significantly more than cats that responded to 0.625 mg AML once daily (4.1 +/- 0.7 kg). The average daily SBP recorded in the 6 cats that completed the study was significantly lower after 16 weeks of treatment (152 +/- 14 mm Hg) compared to day 0 (221 +/- 24 mm Hg). Three cats were euthanized before completion of the study. All 3 cats were responders to AML on day 7. SBPs measured 24 hours after AML administration were similar to the average daily SBP, suggesting that AML effectively controlled SBP for a 24-hour period. AML was shown to be an effective once-daily antihypertensive agent when administered to cats at a dosage of 0.18 +/- 0.03 mg/kg sid.

Primary hyperaldosteronism in the cat: a series of 13 cases

Thirteen cases of feline primary hyperaldosteronism were diagnosed based on clinical signs, serum biochemistry, plasma aldosterone concentration, adrenal imaging and histopathology of adrenal tissue. Two cases presented with blindness caused by systemic hypertension, whilst the remaining 11 cases showed weakness resulting from hypokalaemic polymyopathy. Elevated concentrations of plasma aldosterone and adrenocortical neoplasia were documented in all cases. Seven cases had adrenal adenomas (unilateral in five and bilateral in two) and six had unilateral adrenal carcinomas. Three cases underwent medical treatment only with amlodipine, spironolactone and potassium gluconate; two cases survived for 304 and 984 days until they were euthanased because of chronic renal failure, whilst the third case was euthanased at 50 days following failure of the owner to medicate the cat. Ten cases underwent surgical adrenalectomy following a successful stabilisation period on medical management. Five cases remain alive at the time of writing with follow-up periods of between 240 and 1803 days. Three cases were euthanased during or immediately following surgery because of surgical-induced haemorrhage. One cat was euthanased 14 days after surgery because of generalised sepsis, whilst the remaining cat was euthanased 1045 days after surgery because of anorexia and the development of a cranial abdominal mass. It is recommended that primary hyperaldosteronism should be considered as a differential diagnosis in middle-aged and older cats with hypokalaemic polymyopathy and/or systemic hypertension and should no longer be considered a rare condition.

Cardiopulmonary effects of combinations of medetomidine hydrochloride and atropine sulphate in dogs

Medetomidine and xylazine are alpha 2 adrenoceptor agonists which are used as sedatives and premedicants in small animals. However, bradycardia is a side effect and the use of atropine sulphate has been recommended to counteract it. This study investigated the effects of combining medetomidine (40 micrograms/kg) and atropine (30 micrograms/kg) on the cardiopulmonary function of six dogs. Medetomidine administered alone caused severe bradycardia, but hypertension was mild and transient. Medetomidine and atropine administered together caused an initial bradycardia, but within 15 minutes there was tachycardia accompanied by a mean arterial blood pressure of 210 mm Hg. When atropine was administered 30 minutes before medetomidine, tachycardia and hypertension were observed within five minutes of the medetomidine injection. Thus, although atropine will counteract medetomidine-induced bradycardia, its use results in prolonged and severe hypertension, in association with the tachycardia. Although atropine may be life-saving when bradycardia is profound, its indiscriminate use in combination with alpha 2 adrenoceptor agonists may be disadvantageous.

Blood pressure assessment in healthy cats and cats with hypertensive retinopathy

OBJECTIVE

To determine whether there was an association between hypertensive retinopathy and high systolic, diastolic, and mean arterial blood pressures in cats.

ANIMALS

181 cats.

PROCEDURE

Systolic, diastolic, and mean arterial blood pressures were measured by use of a noninvasive oscillometric technique. The range of blood pressure measurements in healthy cats from various age groups was determined. Associations among systolic, diastolic, and mean arterial blood pressure; hypertensive retinopathy; hyperthyroidism; left ventricular cardiac hypertrophy; chronic renal failure; and serum biochemical abnormalities were determined.

RESULTS

All blood pressure measurements increased with age in healthy cats. The frequency of hypertensive retinopathy also increased with age and with blood pressure, and hypertensive retinopathy was particularly found in cats with systolic blood pressures > 168 mm Hg. There was an increased risk for hypertensive retinopathy in cats that were female, > 10 years old, and neutered. The risk of chronic renal failure also increased as blood pressure, particularly systolic blood pressure, increased.

CONCLUSIONS AND CLINICAL RELEVANCE

Hypertensive retinopathy was common in cats > or = 10 years of age and was associated with systolic blood pressures > 168 mm Hg when measured by the noninvasive oscillometric technique.

Non-invasive blood pressure measurements in cats: clinical significance of hypertension associated with chronic renal failure

The systolic, mean and diastolic pressures as well as the heart rate were measured using the oscillometric method, on a total of 104 cats (60 cats in the normal group, and 44 in the renal disease group) which were brought into Azabu University Animal Hospital. The blood pressure in the normal group was systolic: 115.4 +/- 10.1 mmHg, mean: 96.2 +/- 12.2 mmHg, and diastolic: 73.7 +/- 10.7 mmHg. Although no difference in heart rate, the renal disease group showed significantly (p < 0.05) higher values for systolic, mean, and diastolic pressure when compared with the normal group. Moreover, when plasma renin activity, angiotensin I and II, and aldosterone concentrations were measured in other cats (11 normal and seven with chronic renal failure), all cats with chronic renal failure showed significantly (p < 0.05) higher values than the normal group. It is, therefore, indicated that hypertension due to stimulating renin-angiotensin-aldosterone system may have manifested in cats with renal dysfunction.

Treatment of systemic hypertension in cats with amlodipine besylate

Amlodipine besylate, a calcium channel blocker, was used to treat (mean +/- standard deviation [SD], 127 +/- 68 days) 12 cats with systemic hypertension. Amlodipine was administered orally at a dosage of 0.625 mg per cat (range, 0.08 to 0.23 mg/kg body weight; mean dose +/- SD, 0.17 +/- 0.04 mg/kg body weight) once daily as a single agent. Average indirect systolic blood pressure measurements in the 12 cases decreased significantly from 198 to 155 mmHg during amlodipine treatment. Significant changes in body weight and serum creatinine and potassium concentrations were not detected. Amlodipine appears to be a safe and effective oral treatment for systemic hypertension in cats when used chronically once daily as a single agent.

Calcium kinetics in the aorta of spontaneously hypertensive rats

In the search for abnormalities in hypertensive vessels Ca kinetics was studied in the aorta of spontaneously hypertensive rats (SHR). The uptake of 45Ca was significantly less in hypertensive animals but the uptake of 'Lanthanum resistant' 45Ca was not. The efflux of 45Ca from aorta of SHR was different (P less than 0.01) from that of control rats because of faster initial efflux. The half-life of the first 2 components of efflux curves was significantly shorter in SHR. Results are interpreted as consequences of decreased Ca binding by smooth muscle membrane in hypertensive vessels.

Evaluation of cardiorespiratory effects of combinations of dexmedetomidine and atropine in cats

The cardiovascular effects of dexmedetomidine alone or in combination with atropine were studied in six cats. Cats underwent four treatments in a randomized crossover design as follows: DEX15, saline+dexmedetomidine 15microg/kg; DEX30, saline+dexmedetomidine 30microg/kg; ADEX15, atropine+dexmedetomidine 15microg/kg; ADEX30, atropine+dexmedetomidine 30microg/kg. Pulse rate (PR) and systolic arterial pressure (SAP) decreased in DEX15 and DEX30. Premedication with atropine was effective in preventing bradycardia (PR<100 beats/min) and resulted in a biphasic effect in blood pressure. Hypertension was followed by a gradual decrease in SAP. Rate pressure product decreased in DEX15 and DEX30 whereas in ADEX15 and ADEX30 it remained within baseline values for at least 60min. Although premedication with atropine in cats sedated with dexmedetomidine prevents bradycardia, it induces hypertension and increases myocardial oxygen consumption. The magnitude of cardiovascular effects produced by dexmedetomidine in cats does not seem to be dose-related.

Hypertension and renal disease

Systemic hypertension is commonly associated with chronic renal failure in dogs and cats. Consequences of systemic hypertension are manifested by pathologic changes involving the eyes, heart, central nervous system, and/or kidneys. These changes may be prevented or reversed by diagnosing and treating systemic hypertension. Therefore, blood pressure determination and ophthalmic examination should be performed routinely in animals with chronic renal failure. Therapy for systemic hypertension associated with chronic renal failure should be initiated cautiously with the goal being to lower arterial pressure below values considered to be hypertensive. Therapy may involve nonpharmacologic strategies and/or hypertensive drugs. This article discusses pathophysiologic mechanisms, consequences, diagnosis, and treatment of systemic hypertension associated with chronic renal failure in dogs and cats.

Comparative pathology of the enlarged carotid body

A histological study was made of the carotid bodies of man and various animal species from low and high altitudes. The animals studied were the alpaca, llama, cattle, guinea-pig, rabbit, dog, rat and man. As well as a qualitative microscopic study, a differential cell count was carried out to determine the percentage of the light and dark variants of chief cells and of sustentacular cells present. The investigation showed that the carotid bodies enlarge in cattle, guinea-pigs and rabbits living in the hypobaric hypoxia of high altitude to which they have to acclimatize. The carotid bodies are not enlarged in llamas and alpacas which show Darwinian adaptation to high altitude. There is no single histopathological appearance to be found with enlargement of the carotid body; on the contrary, there appears to be a characteristic histological reaction for different species. Thus, man shows hyperplasia of sustentacular cells, cattle show focal dark cell proliferation and rabbits, guinea-pigs, and dogs show striking hyperplasia and vacuolation of chief cells. In the rat, the enlargement of the carotid body is not characterized by the differential proliferation of any specific element and, as a result, it does not appear to be a good model for the human organ. In man and rat, carotid body enlargement occurs in response to systemic hypertension as well as to chronic hypoxaemia and the histological response to the 2 stimuli is the same, depending on the species. The normal rabbit carotid body is more reminiscent of that of man but, in this species, the reaction of glomic tissue differs from that of human glomic tissue.

Diagnosis and treatment of systemic hypertension

Systemic hypertension is often observed in dogs and cats with chronic renal failure and other metabolic and endocrinological abnormalities. High systemic arterial blood pressure has been associated with chronic renal failure, ocular injury, neurologic complications, and cardiovascular changes. Recent advances in our knowledge of the prevalence and consequences of systemic hypertension dictate that proper diagnosis and treatment of this problem should become a component of routine therapy for many of our patients.