Haemodynamic Frailty: A threat

Sayak Banerjee, Amity University Kolkata

Haemodynamic Frailty and its associated disorders

Frailty is defined as a clinically recognized state of increased vulnerability causing an ageing-associated functional decline in the advancing years. This decline takes place across several physiological systems resulting in compromised acute stressors. It is a pre-morbid condition in which the individual is in an increased state of disease. The compromised energetics that is associated with the vulnerability is low energy, slowed walking speed, low grip strength, and unintentional weight loss.  Concerning the cardiovascular system, adaptive hemodynamic control strengthens the appropriate functioning of various organs and tissues in the body. Any defect in the hemodynamic regulation damages the response to stressors, thus increasing the susceptibility to multiple diseases. These diseases arise from cognitive and cerebrovascular disorders, gastrointestinal disorders, stroke, acute heart failure, dizziness, hypovolaemic shock, and acute kidney injury (AKI). This state of predisposition to disease linked with partial limitation in adaptive hemodynamic responses is known as haemodynamic frailty (HDF).

AKI is caused due to a sudden decline in renal function and is associated with increased concentrations of serum creatine (sCr) or a decrease in urinary output. The prevalence of the disease has been increasing and it is said to be a major clinical issue connected with high levels of morbidity and mortality. Generally, AKI is followed by the need for dialysis and death. Nevertheless, long-term consequences result in either an amplified cardiovascular risk or chronic lung disease. Although AKI can affect people of all ages, intensive medicinal care is required for the aged. This is because, in the elderly, mortality rates can reach more than 50%. The occurrence of the disease in the elderly is 3-55 fold higher than among younger individuals. The increased propensity of acute kidney injury in the elder ones is linked with not only decreased renal function, but also changes in renovascular reactivity, polypharmacy, and co-morbidities. On the other hand, dehydration by itself is a major risk factor.

Dehydration and Acute Kidney Injury

With respect to body weight, the total body water (TBW) declines with age. This is due to the loss of lean mass and the accumulation of fat. TBW is controlled by counterbalancing water gains from eating and drinking, with water loss from perspiration, urine production, excretion of faeces, and respiration. Frequent hypovolemia and hypernatremia activate the release of antidiuretic hormone (ADH) and decrease atrial natriuretic peptide (ANP) secretion, resulting in reduced natriuresis and diuresis. Thus, the reduced capacity to engage these adaptive responses is a feature of Haemodynamic Frailty in the elderly. Hence, dehydration in the elderly can be regarded as a key characteristic of Haemodynamic Frailty and could be the cause of the progression of diseases like acute kidney injury. 

AKI can be broadly classified as pre-renal, intrinsic, or post-renal in origin with overlapping characteristics. Pre-renal AKI results from a reduction in renal blood flow (RBF) or net glomerular filtration pressure due to low blood pressure (BP) or impaired autoregulation. An altered equilibrium in the contractile status of afferent and efferent arterioles leads to impaired autoregulation. Intrinsic AKI stimulates the tubuloglomerular feedback mechanisms that decrease the glomerular filtration rate (GFR). This reduction causes arteriolar vasoconstriction and consequently a decrease in intraglomerular pressure and RBF. Systemic effects in the distal organs result in injury to the kidney. The decrease in GFR alone might lead to uremia and azotemia, which induce the dysfunction of other organs and can bring upon death. Dehydration is involved in all three AKI sub-types but being a part of Haemodynamic Frailty, the scientists have focused on pre-renal and intrinsic acute kidney injury.

Assessment and Inference from the findings

The researchers concluded that the inability to regulate water balance is a defining feature of HDF in the elderly. It can make the individuals susceptible to pre-renal and intrinsic acute kidney injury. For prevention of the disease, stressors like toxins, drugs, habits, etc. should be avoided in high-risk patients. Moreover, convenient stressors might be permitted in hemodynamically stable and well-hydrated patients. Several non-invasive methods are available for the determination of intravascular volume. However, the technologies require to be optimized and normalized for the estimation of HDF. Further studies involving the assessment of Haemodynamic Frailty are essential with regards to mitigating acute kidney injury risk in the elderly.

Also read: Studying p38-MAPK – A signaling pathway in mice embryos

Source: Docherty, Neil G., et al. “Haemodynamic Frailty – A Risk Factor for Acute Kidney Injury in the Elderly.” Ageing Research Reviews, vol. 70, Sept. 2021, p. 101408.  DOI:http://10.1016/j.arr.2021.101408.

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About the Author: Sayak Banerjee is a 3rd-year Biotechnology Engineering Student with a great interest in Immunology and Molecular genetics. He is a creative scientific writer in Bioxone with an inclination towards gaining knowledge regarding vast sections of Biotechnology and emphasizing himself in various wet lab skills.