Hypertension in dialysis: pathophysiology and treatment

Hypertension is a major modifiable risk factor for cardiovascular disease, which is the main cause of morbidity and mortality in the dialysis population; therefore, blood pressure (BP) values of <140/90 mmHg (or <160/90 mmHg in the elderly) are recommended. As extra-cellular volume (ECV) expansion is the main pathophysiological determinant of hypertension in dialysis patients, efforts should be made to correctly estimate and achieve the patient's dry body weight. Adequate dialysis treatment time, avoiding the high ultrafiltration rates associated with short treatment times, can greatly help in controlling BP values, at least in part by improving cardiovascular stability. The most promising tool in reducing cardiovascular instability is the use of the conductivity kinetic model, which is easy to apply at each dialysis session without any extra-cost and can also provide information on dialysis dose and vascular access function. On-line monitoring of blood volume (BV) changes has also been used. Convective techniques have long been claimed as providing better cardiovascular stability, compared to diffusive techniques, but solid evidence is still lacking. Anti-hypertensive drugs should be used only when, despite the patient being at his dry body weight, BP values are not adequately controlled. There are no studies specifically addressing which classes of anti-hypertensive drugs provide better organ-protection in dialysis patients. However, the current opinion is that adequate BP control should be guaranteed, irrespective of which classes of drugs are used. Then, ACE inhibitors, angiotensin II receptor antagonists and beta-blockers may be recommended as first choice drugs, given their protective effects in patients at high risk for, or affected by, cardiovascular disease.     

Hypertension in chronic hemodialysis patients: current view on pathophysiology and treatment

BACKGROUND: Hypertension accounts for 65 - 85% of patients beginning dialysis, and dialysis alone controls hypertension in over 50% of patients. PATIENT AND METHODS: We have surveyed the status of BP control in 113 hemodialysis patients, 66 men and 47 women, aged 59 +/- 13 years old, with a mean duration on hemodialysis 42 +/- 44 months. The following measurements were recorded: predialysis mean arterial pressure (pre-MAP), post-dialysis MAP (post-MAP), percentage of change in MAP, pre-dialysis weight, post-dialysis weight, fluid removed by ultrafiltration during each dialysis session, interdialytic weight gain and excess weight over the desirable dry weight. RESULTS: Our results showed a hypertension prevalence of 59% (hypertension defined as pre-MAP +/- 110 mmHg). MAP was not different between men and women, and only 4.5% of patients had isolated systolic hypertension. All hypertensive patients were on treatment with antihypertensives. Reduction in post-MAP by > or = 5% (controlled by ultrafiltration) was found in 68.5% of hypertensive and in 87.5% of normotensive patients. Age, primary renal disease, time on dialysis and adequacy of dialysis were not correlated with pre-MAP. Excess volume and interdialytic weight gain were found to correlate with pre-MAP (p = 0.03). Also, the weekly dosage of EPO had a significant correlation with pre-MAP (p = 0.03). No differences were found among four classes of antihypertensive drugs regarding the BP control. Patients with hypertension requiring one drug achieved a significantly (p < 0.05) lower pre-MAP than the group of patients receiving three or more drugs. In conclusion, hemodialysis population shows high prevalence of hypertension, resistant to antihypertensive treatment. CONCLUSION: Current methods of hemodialysis are not effective in controlling BP. This implies that more insight into the role of excess volume and vasomotor systems in the pathogenesis of dialysis hypertension is warranted.     

Hypertension in children with chronic kidney disease: pathophysiology and management

Arterial hypertension is very common in children with all stages of chronic kidney disease (CKD). While fluid overload and activation of the renin–angiotensin system have long been recognized as crucial pathophysiological pathways, sympathetic hyperactivation, endothelial dysfunction and chronic hyperparathyroidism have more recently been identified as important factors contributing to CKD-associated hypertension. Moreover, several drugs commonly administered in CKD, such as erythropoietin, glucocorticoids and cyclosporine A, independently raise blood pressure in a dose-dependent fashion. Because of the deleterious consequences of hypertension on the progression of renal disease and cardiovascular outcomes, an active screening approach should be adapted in patients with all stages of CKD. Before one starts antihypertensive treatment, non-pharmacological options should be explored. In hemodialysis patients a low salt diet, low dialysate sodium and stricter dialysis towards dry weight can often achieve adequate blood pressure control. Angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers are first-line therapy for patients with proteinuria, due to their additional anti-proteinuric properties. Diuretics are a useful alternative for non-proteinuric patients or as an add-on to renin–angiotensin system blockade. Multiple drug therapy is often needed to maintain blood pressure below the 90th percentile target, but adequate blood pressure control is essential for better renal and cardiovascular long-term outcomes.     

Hypertension and hemodialysis: pathophysiology and outcomes in adult and pediatric populations

Hypertension is prevalent in adult and pediatric end-stage renal disease patients on hemodialysis. Volume overload is a primary factor contributing to hypertension, and attaining true dry weight remains a priority for nephrologists. Other contributing factors to hypertension include activation of the sympathetic and renin–angiotensin–aldosterone systems, endothelial cell dysfunction, arterial stiffness, exposure to hypertensinogenic drugs, and electrolyte imbalances during hemodialysis. Epidemiologic studies in adults show that uncontrolled hypertension results in cardiovascular morbidity, but reveal increased mortality risk at low blood pressure, so that it remains unclear what the target blood pressure should be. Despite the lack of a definitive BP target, gradual dry weight reduction should be the first intervention for BP control. Renin–angiotensin–aldosterone system inhibitors have been shown to improve cardiovascular morbidity and mortality and are recommended as the initial pharmacologic therapy for hypertensive hemodialysis patients. Short-daily or nocturnal hemodialysis are also good therapeutic options for these patients. It is already established that hypertension in pediatric hemodialysis patients is associated with adverse cardiovascular outcomes, and there is emerging evidence that the mechanisms causing hypertension are similar to adults. Hypertension in adult and pediatric hemodialysis patients warrants aggressive management, although clinical trial evidence of a target BP that improves mortality does not currently exist.     

Wrestler's ear: pathophysiology and treatment.

Management of auricular hematomas has always been a challenge for physicians. This injury is very common among wrestlers since early olympic competition times. Initial treatment usually involves simple aspiration and a compression bandage. Most of these hematomas recur; then it must be decided how to manage this recurrent problem and the eventual "cauliflower ear." A treatment is proposed that directs attention to the pathophysiology of the injury and involves total excision of the newly formed fibroneocartilaginous layer. Unless this layer is successfully removed the hematoma will persist and a thickened ear will result. This treatment can be performed on an outpatient basis under local anesthesia and allows immediate resumption of wrestling competition.     

Acute acalculous cholecystitis: pathophysiology and treatment

The absence of reliable correlation between clinical features and pathological evolution and the molteplicity of risk factors, often related to various pathophysiological pathways, make of acute acalculous cholecystitis a clinical entity well distinct from other affecting gallbladder. In spite of the slight incidence, its occurrence among serious multiple trauma patients may reach 90%. The arguability of diagnostic criteria and the missed or delayed recognition, then affecting timing of surgery are important in determining morbidity and mortality of this condition. The Authors reviewed 16 patients operated for acute acalcolous cholecystitis. US, although sometimes underestimate the severity of affection and cause false negatives, had been the first choice investigation because of its rapidity, facility of execution and repeatability. TC adds subsequent information when US images were doubtful and reveleated pericholecystic involvement more carefully. Hepatobiliary scintigraphy has high diagnostic accuracy but needs of too long execution time. Reasons of early cholecystectomy lay on clinical and experimental evidences that focal or diffuse ischemic damage of gallbladder's wall may affect natural history of the illness and infectious overwhelming is a late event. Surgical intervention has been performed in 16 patients, must within 24 hours. Morbility has been very low, mortality scored 18.7%.     

Nephrogenic acute respiratory distress syndrome: A narrative review on pathophysiology and treatment on pathophysiology and treatment

The kidneys have a close functional relationship with other organs especially the lungs. This connection makes the kidney and the lungs as the most organs involved in the multi-organ failure syndrome. The combination of acute lung injury (ALI) and renal failure results a great clinical significance of 80% mortality rate. Acute kidney injury (AKI) leads to an increase in circulating cytokines, chemokines, activated innate immune cells and diffuse of these agents to other organs such as the lungs. These factors initiate pathological cascade that ultimately leads to ALI and acute respiratory distress syndrome (ARDS). We comprehensively searched the English medical literature focusing on AKI, ALI, organs cross talk, renal failure, multi organ failure and ARDS using the databases of PubMed, Embase, Scopus and directory of open access journals. In this narrative review, we summarized the pathophysiology and treatment of respiratory distress syndrome following AKI. This review promotes knowledge of the link between kidney and lung with mechanisms, diagnostic biomarkers, and treatment involved ARDS induced by AKI.     

Persistent postoperative enterocutaneous fistula: pathophysiology and treatment

The cause of an enterocutaneous fistula following an abdominal operation, in the absence of inflammatory bowel disease or irradiation damage, is often obscure. In this study, it is postulated that distal obstruction, associated with peritoneal adhesions or abscess, is the critical determinant of fistula persistence. The 'venting' effect of the fistula, and the presence of obstruction which is frequently partial, makes recognition of the obstructive element difficult. It is suggested that operations to cure postoperative fistula should be based on the assumption that distal obstruction is always present, and should include a complete lysis of adhesions involving the small and large bowel. A postoperative fistula was cured in 21 out of 23 patients treated on this basis.     

Allopurinol-induced recurrent DRESS syndrome: pathophysiology and treatment

Hyperuricemia is present in approximately 5% of the population. The vast majority is asymptomatic and at no clinical risk. Allopurinol, an analog of hypoxanthine, has been widely used in clinical practice for more than 30 years for the treatment of hyperuricemia and gout. Two percent of patients develop a mild exanthema when on this drug, which usually resolves after withdrawal of the drug. A syndrome characterized by exfoliative dermatitis, hepatitis, interstitial nephritis, and eosinophilia, termed allopurinol hypersensitivity syndrome, has been described, and its etiology related to the accumulation of one of allopurinol's metabolites, oxypurinol, of which clearance is decreased in the setting of renal insufficiency and the use of thiazide diuretics. The term DRESS (Drug Rash with Eosinophilia and Systemic Symptoms) Syndrome has been recently used to describe an entity presenting with similar features.     

Varicocele: Current controversies in pathophysiology and treatment

Although varicocele is generally regarded as the most common and easily correctable cause of male factor infertility, controversy continues to surround its pathophysiology and treatment. Most likely, a varicocele is the result of a multifactorial process including a longer left internal spermatic vein with its right‐angle insertion into the left renal vein and the absence of valves, which causes a higher hydrostatic pressure resulting in dilatation. Much of the pathophysiology is still unknown, increased blood flow causing an elevated intratesticular temperature may be important. The best method for diagnosis remains a good clinical examination. A key to patient counselling regarding varicocele treatment is an understanding of outcomes data and various predictive factors for response. Positive gonadotrophin‐releasing hormone stimulation test, normal serum follicle‐stimulating hormone level, grade III varicocele, normal testicular size, total motile sperm count more than 5 million per ejaculate and absence of genetic defect are associated with improved outcomes following varicocelectomy. Surgical ligation is still the preferred method of treatment. Percutaneous treatment is reserved for recurrent varicoceles after failure of surgical ligation.      

Hypertension in chronic renal failure and ESRD: prevalence, pathophysiology, and outcomes

Hypertension and cardiovascular disease were detected to be major problems in end-stage renal disease patients soon after the application of chronic dialysis to treat uremia. Nearly 40 years later, and despite awesome technological and pharmacological advances, cardiovascular diseases remain the number one cause of death in all categories of renal patients, ie, chronic renal insufficiency, end-stage renal disease on dialysis and the renal transplant recipient. This is quite likely related to the massive clinical burden of cardiovascular risk factors: hypertension, cardiac fibrosis and hypertrophy, abnormal lipid profiles, smoking, dietary factors, and enhanced sympathetic activity. For example, left ventricular hypertrophy and abnormal echocardiograms are present in up to 75% to 80% of incident dialysis patients related to the interactions of these cardiovascular risks. It is important to understand how hypertension and the other cardiovascular disease risk factors interact in these patients. Based on the latest national data from the USRDS, the prevalence of underlying cardiac disease is increasing during the period of chronic renal failure. A proper understanding of the pathophysiology and prevalence of hypertension and its consequences in renal patients may lead to more rational therapies and clinical trials. At this time, the nephrologists are dealing with an epidemic of cardiovascular diseases in their patients.     

Atrial fibrillation after cardiac surgery: pathophysiology and treatment

Atrial fibrillation (AF) occurs in 25% to 60% of patients after cardiac surgery. It is most consistently associated with advanced age and valvular heart operations. Despite improving knowledge of the pathophysiology of chronic AF, postoperative AF remains an obstinate clinical problem. It is associated with an increased risk of stroke, longer hospital stay, and higher hospital expenditure. Consequently, there has been great interest in strategies to prevent and treat this arrhythmia. Treatment for postoperative AF may require immediate electrical cardioversion for hemodynamically unstable patients. Heart rate control is useful in most patients, with anticoagulation considered after 48 hours. Antiarrhythmic therapy is often effective in restoring sinus rhythm but its use needs to be balanced against the patient's risk of proarrhythmic side effects such as torsade de pointes.     

Hyponatremia: pathophysiology and treatment,a pediatric perspective

Hyponatremia is the most commonly observed electrolyte abnormality in hospitalized children. The most serious consequences of hyponatremia and its treatment involve the central nervous system (CNS). Important factors determining the development of clinical symptomatology include: the rate of fall in serum sodium, and the severity and duration of hyponatremia. Acute hyponatremia is associated with increased brain water resulting in varying grades of encephalopathy whereas the osmoregulatory mechanism allows normalization of CNS water content in chronic hyponatremia. It is recommended that the therapy for hyponatremia be initiated on the basis of the presence or absence of symptoms. An increase of 4–6 mmol/l in serum sodium over 10–15 min is recommended in symptomatic patients. Rapid correction of chronic hyponatremia may result in osmotic dehydration syndrome and therefore should be avoided.     

Post-dural puncture headache: pathophysiology, prevention and treatment

Post-dural puncture headache (PDPHA) has been a vexing problem for patients undergoing dural puncture for spinal anaesthesia, as a complication of epidural anaesthesia, and after diagnostic lumbar puncture since Bier reported the first case in 1898. This Chapter discusses the pathophysiology of low-pressure headache resulting from leakage of cerebrospinal fluid (CSF) from the subarachnoid to the epidural spaces. Clinical and laboratory research over the last 30 years has shown that use of small-gauge needles, particularly of the pencil-point design, is associated with a lower risk of PDPHA than traditional cutting point needle tips (Quincke-point needles). A careful history can rule out other causes of headache. A positional component of headache is the sine qua non of PDPHA. In high-risk patients (e.g. age < 50 years, post-partum, large-gauge-needle puncture), patients should be offered early (within 24-48 h of dural puncture) epidural blood patch. The optimum volume of blood has been shown to be 12-20 ml for adult patients. Complications of autologous epidural blood patch are rare.     

Severe hypertension in children and adolescents: pathophysiology and treatment

Severe, symptomatic hypertension occurs uncommonly in children, usually only in those with underlying congenital or acquired renal disease. If such hypertension has been long-standing, then rapid blood pressure reduction may be risky due to altered cerebral hemodynamics. While many drugs are available for the treatment of severe hypertension in adults, few have been studied in children. Despite the lack of scientific studies, some agents, particularly continuous intravenous infusions of nicardipine and labetalol, are preferred in many centers. These agents generally provide the ability to control the magnitude and rapidity of blood pressure reduction and should—in conjunction with careful patient monitoring—allow the safe reduction of blood pressure and the avoidance of complications. This review provides a summary of the underlying causes and pathophysiology of acute severe hypertension in childhood as well as a detailed discussion of drug treatment and the optimal clinical approach to managing children and adolescents with acute severe hypertension.