Overview

Intensive care refers to the use of advanced medical technology, modern monitoring equipment and the implementation of intensive care for all types of critically ill patients admitted to the hospital. The aim is to maximize the patient’s survival and subsequent quality of life. Research within this field is based on a combination of both basic and clinical medicine alongside innovating new intervention techniques to conduct a more comprehensive understanding of critical illness and effective treatment. Intensive care focuses on patients that are critically ill.

1. Disease types

Patients in the intensive care unit are treated for a wide variety of critically acute and reversible diseases. Examples of such as myocardial infarction, coronary heart disease, extensive burns (Burn Unit), cerebrovascular accidents (Neurological ICU). For patients that are in terminal stages of cancer, patients that are brain dead but with a heartbeat and various severe infections are not admitted to the intensive care unit.

2. Clinical Manifestations

Clinical manifestations of cardiovascular disease: Retrosternal crushing chest pain, angina, referred pain in the left back/arm, palpitations, dyspnea, increased difficulty breathing, paroxysmal nocturnal dyspnea, edema, cyanosis, syncope, cough, hemoptysis, weakness, belching, upper abdominal pain, nausea and vomiting.
Patients with impaired renal function may be associated with skin symptoms such as hyperpigmentation, calcium deposition, itching, difficulty in sweating, and ulceration. Some patients may have hypogonadism, manifested as gonadal maturation or atrophy, low libido, amenorrhea and infertility.

Investigation and Diagnosis

ReLIA’s Biomarker Guide

1. N terminal pro-brain natriuretic peptide (NT-proBNP)

Compared to BNP, NT-proBNP has a longer half life (1-2 hours compared to BNP’s 20 minutes), a higher concentration in blood (15-20 times that of BNP) and is also biologically inactive. It also wont be affected by BNP related drugs. Therefore, NT-proBNP is recognized as a good biochemical marker that reflects cardiac function. It can be used to diagnose symptomatic heart failure, estimate the prognosis of patients with heart failure and acute coronary syndrome and to monitor treatment.

2. Heart-type fatty acid binding protein (H-FABP)

H-FABP is small cytoplasmic protein that is involved in the growth and differentiation of cardiomyocytes. Blood levels of h-FABP in normal people are very low or absent. However, these levels will rapidly increase in acute myocardial infarction. Studies have shown that h-FABP is more specific to myoglobin in myocardial damage. It is therefore a novel biomarker in the early detection of myocardial infarction.

3. Neutrophil gelatinase-associated lipocalin (NGAL)

Blood and Urine NGAL concentrations increase rapidly in acute renal injury (from causes such as cardiac surgery, kidney transplantation, renal ischemia, nephrotoxicity). Levels are most significant in 2 hours as compared to 24-72 hours for serum creatinine and urinary enzymes. NGAL can also reflect the severity of kidney damage. Changes in serum NGAL levels are monitored to assess patient recovery and whether hemodialysis is required after transplantation. NGAL levels are also used to assess the severity of AKI (RIFLE criteria) and are also used to accurately predict whether patients require renal replacement therapy (Accuracy AUC ROC of 0.82)

NGAL is also one of the prognostic indicators of acute kidney injury. There is a positive correlation between urinary NGAL levels at 2, 4 and 6 hours after a cardiopulmonary bypass to duration of hospital stay. Finally, urinary NGAL levels predict whether dialysis treatment is required within one week of renal transplant patients and to assess kidney function after 3 months.

4. Beta-2 microglobulin (β2-MG)

Under normal conditions, 99.9% of human beta-2 microglobulin is reabsorbed and broken down in the epithelial cells of the proximal tubules. Increased levels of β2-MG are indicative of renal tubular damage or an increase in filtration load. β2-MG concentrations in blood and urine significantly increase in patients who have just had renal transplants. If it increases further it suggests transplant rejection. Finally, urine β2-MG levels help differentiate upper and lower urinary tract infections (UTI); urine β2-MG levels increase in upper UTI’s, but don’t change in lower UTI’s.

5. Cystatin-C

Cystatin-C is a protein that is expressed in all nucleated cells. It is produced at a constant rate and stays present regardless of age, sex, body weight, inflammation and other interfering factors., It can be freely filtered from the glomerulus and is reabsorbed and broken down in the epithelial cells of the proximal tubules. Furthermore, Cys-C is not secreted in the lumen. Therefore, impairment in renal function/GFR can leads to increases in blood Cys-C levels (> 10 times that of normal patients). If tubular cells are damaged, the amount of Cys-C that is reabsorbed and broken down substantially decreases, leading to an increase in urine Cys-C levels (>100 times that of normal patients).

6. D-dimer

D-dimer is a fibrin degradation product present after fibrinolysis. Blood levels of D-dimers increase in disseminated intravascular coagulation, kidney disease, organ transplant rejection and thrombolytic therapy. As long as there is active thrombotic and fibrinolytic activity in the body, levels of D-dimers will rise. For elderly or hospitalized patients, elevated D-dimer levels can be due to abnormal coagulation caused by bacteremia or other diseases.