**2. Acute complications during haemodialysis**

We will discuss some of the common acute complications that occur during routine haemodialysis sessions and are categorized as below:

#### **2.1 Cardiovascular complications**

The common cardiovascular complication that may occur during haemodialysis include:

*2.1.1 Intradialytic hypotension(IDH)*

IDH is defined as, decrease in systolic blood pressure by ≥20 mmHg or a decrease in MAP of ≥10 mmHg associated with symptoms of dizziness, restlessness or need for intervention by a supporting staff. It occurs in about 10–40% of dialysis treatment, the discrepancy in prevalence is not known exactly but may be due to use of various definition of IDH (**Table 1**) [1, 2].

Pathogenesis of IDH is complex and includes:

1.Excessive ultrafiltration.

2.Reduce plasma filling.

3.Cardiac disease.

4.Dialyzer reaction.

5.Haemolysis.

Leading to reduced effective circulating volume and subsequently intradialytic hypotension.

Clinical features include; abdominal discomfort, nausea and vomiting, muscle cramp, dizziness and anxiety.

IDH is associated with several notable clinical consequences, the most common are cardiovascular events and mortality.

It is associated with myocardial stunning, a reversible phenomenon that occurs due to repetitive ischemia with each episode of IDH and may initiate myocardial fibrosis and irreversible systolic dysfunction. Similarly reduced cerebral perfusion with each episode of IDH is associated with an increased risk of new-onset dementia. IDH also accelerates the loss of residual renal function with repeated episodes of hypotension, and less commonly IDH is also associated with vascular access thrombosis and mesenteric and liver ischemia.

Management strategy includes:

Several approaches have been suggested to treat IDH which include:

1.Immediate treatment:


### 2.Prevention

	- a.A cool dialysate below core body temperature induces vasoconstriction and activates sympathetic nervous system decreasing the risk of IDH.

## *2.1.2 Intradialytic hypertension*

Intradialytic hypertension is a paradoxical rise in blood pressure that occurs during a haemodialysis procedure. it is another common complication that occurs in about 8–30% of dialysis sessions and is associated with high mortality [1, 3].

There are no accepted criteria, however, is commonly defined as a rise of systolic blood pressure >10 mmHg during HD, a rise of MAP > 15 mmHg during or immediately post-HD and/or any rise of blood pressure during HD.


#### **Table 1.**

*Different definitions of intradialytic hypotension.*

Etiopathogenesis of interdialytic hypertension includes:

Pathogenesis of intradialytic hypertension is unknown. However, it represents a state of volume overload, sympathetic overactivity, RAAS activation, endothelial dysfunction, increased level of endothelin 1, ESAs and sodium loading during dialysis.

Treatment includes:

During dialysis treatment should be done once SBP >180 mmHg during dialysis. Interdialytic hypertension is best treated with drugs like clonidine or RAAS blockers like enalapril, other antihypertensive agents can be used as well.

Preventive measures include:


There are several antihypertensive agents used in a patient under maintenance dialysis and the knowledge of dializability will help in adjusting the dose of drugs. The dialyzable drugs need to be repeated after a haemodialysis session (**Table 2**).


In a study performed in haemodialysis patients, dry weight reduction in hypertensive haemodialysis patients (DRIP) suggested that optimal control of BP in HD is via control of extracellular fluid volume and not the use of antihypertensive agents [4].
