Managing a Patient on Dialysis	46
Arghya Majumdar and Raj Kumar Mani

A 60-year-old diabetic and hypertensive male patient, with a history of coronary artery bypass grafting a year ago, was admitted to the ITU, with pneumonia and septic shock. He was started on vasopressors. He remained oliguric (urine output <30 mL/h) for more than 12 h, with creatinine 2 mg/dL, potassium 6.5 mEq/L, and pH 7.1. He was commenced on continuous renal replacement therapy (CRRT).

Patients on dialysis need close supervision due to their underlying unstable clinical state, hemodynamic effects of extracorporeal circulation, and technical problems commonly encountered during renal replacement therapy (RRT).

Step 1: Ensure all possible steps to prevent acute kidney injury (AKI) (Table 46.1)

•AKI is a preventable condition, and all attempts should be made to avoid the kidney damage as the mortality doubles once renal failure sets in.

Step 2: Recognize the need to start RRT

•Volume overload/pulmonary edema which is refractory to combination of high-dose loop diuretics (e.g., frusemide + metolazone).

•Refractory hyperkalemia (>6.5 mEq/L) persisting after failure of medical measures (e.g., calcium chloride i.v. 10% of 10 mL, i.v. insulin with dextrose, potassium exchange with enteral calcium resonium, i.v. sodium bicarbonate, and nebulized beta-agonist).

A. Majumdar, M.D., M.R.C.P. (*)

Department of Nephrology, AMRI Hospitals, Kolkata, India e-mail: [e-mail]

R.K. Mani, M.D., F.R.C.P.

Department of Pulmonology and Critical Care, Artemis Health Institute,

Gurgaon, India

R. Chawla and S. Todi (eds.), ICU Protocols: A stepwise approach,	369
DOI 10.1007/978-81-322-0535-7_46, © Springer India 2012

370	A. Majumdar and R.K. Mani

Table 46.1 Preventive measures for AKI

1. Resuscitate with adequate fluid and administer antibiotics promptly

2. Avoid nephrotoxic antibiotics, nonsteroidal anti-inflammatory drugs, or radiocontrast agents

3. Improve cardiac output (e.g., dobutamine) to increase renal perfusion

4. Use minimum vasopressor to keep mean arterial pressure of more than 60 mmHg

5. Avoid “renal-dose” dopamine

6. Measure and manage raised intra-abdominal pressure

•Severe metabolic acidosis (pH < 7.1).

•Anuria. RRT becomes necessary to create space for intravenous fluid, drugs, and nutrition.

•Uremic encephalopathy.

•Uremic pericarditis.

•Ideal time to start RRT is controversial, and a joint decision between the nephrologist and the intensivist should be made.

Step 3: Establish vascular access for dialysis

•Urgent vascular access may be achieved by inserting a double-lumen hemodialysis catheter, preferably under (USG) ultrasonographic guidance.

•Coagulation profile and platelet count should be checked.

•A tunneled line may be preferable if the access is expected to be kept in for a long time, if there are multiple malfunctioning temporary catheters, or if the patient is going to receive immunosuppressive treatment.

•Site

–Central vein—internal jugular (IJ), subclavian (SC), or femoral (F).

–IJ is the preferred route.

–SC route may be opted for, if the patient has a tracheostomy, but it should be avoided to prevent subclavian vein stenosis, which may restrict future vascular access for dialysis like fistula in the arm.

–Femoral route is accompanied by increased risk of infection and/or thrombosis, but it is preferred as a short-term measure in severely coagulopathic patient.

•Size: 11.5 Fr and length of catheter: 13.5 cm for (R) IJ or SC, 16.5 cm for (L) IJ or SC, and 19.5 cm for F.

•Meticulous sterile handling of dialysis line by health-care workers is mandatory.

•The hemodialysis line should not be used for any other purpose.

•After each dialysis session, heparin lock should be used. In spite of heparin lock, if there is a clot formation inside the catheter, attempt at clot lysis may be made by instilling thrombolytic agent like 2 mg of alteplase into each catheter lumen.

•Platelet counts should be followed periodically.

Step 4: Start CRRT (see Chap. 45)

•Patients in shock with high dose of vasopressor should ideally be started on CRRT.

–Use central venous double-lumen hemodialysis catheter, which will ensure a blood flow of at least 200 mL/min.

46 Managing a Patient on Dialysis	371

–Before starting, check electrolytes, arterial blood gas, and lactate.

–If custom-made fluid is not available, one has to improvise on substitution fluids, maintaining the balance of essential electrolytes. Custom-made fluids often have lactate. If liver function is impaired, it may not be converted to bicarbonate and lead to worsening of hyperlactatemia.

–Electrolytes like Na, K, Ca, and Mg should be monitored frequently.

–If the patient is very catabolic and higher solute clearance is required, substitution fluid should be added postdilution (i.e., after the filter) to maintain a higher diffusion gradient of solutes. On the other hand, in situations where one needs to avoid anticoagulation, it may be added prefilter (i.e., predilution). Heparin is the safest anticoagulant. Target an APTT of 1.5–2 times the control. If the patient has coagulopathy, regional anticoagulation may be tried with heparin/protamine or one may try prostacyclin. If citrate is used, ensure that all fluids are free of calcium. Calcium has to be added separately as an infusion, with regular monitoring.

–Convection at 20 mL/kg/h has been shown to be as effective as 35 mL/kg/h. Some studies have found a benefit of high volume ultrafiltration in sepsis.

–Adjust the dose of drugs especially antibiotics. Roughly one may use the dosing for the glomerular filtration rate at 10–15 mL/min.

–Hourly ultrafiltrate rate depends on central volume status (guided by invasive hemodynamic monitoring, if needed) and hourly fluid intake and output.

–Change the circuit, at least once in 72 h.

–Protein intake should be planned, taking into account the daily loss on CRRT

–(40 g/day, over and above 1.5 g/kg/day).

–Water-soluble vitamins should be replaced daily.

Step 5: Use slow extended dialysis (SLED), as a step-down dialytic support or initial support in less hemodynamically unstable patients

•This can be done when the patient is recovering from shock.

•A modified hemodialysis machine will suffice for SLED.

•The dialysate flow rate can be adjusted to 100–200 mL/min.

•SLED can be done for 8–10 h at one stretch, during the daytime, enabling better utilization of skilled dialysis staff and resources.

•The patient can be mobilized for investigations and procedures.

•Drug dosing should be adjusted accordingly. Supplemental doses of most antibiotics are needed after a session.

•Partial TPN may be given in between sessions when required.

Step 6: Manage the patient with conventional intermittent hemodialysis (HD) once hemodynamically stable

•Ensure a vascular access blood flow of 250–400 mL/min.

•Dialysate flow may be varied from 300 to 800 mL/min.

•Pre-HD potassium should be checked. Dialysate fluids have a potassium level of 2.2 mmol/L. So if serum potassium is less than 3.5 mmol/L, potassium should be replaced accordingly.

372	A. Majumdar and R.K. Mani

•In cases of severe hyperkalemia or hypercalcemia, dialysate fluids without potassium or low calcium may be used.

•A bolus of heparin, usually 1,000–2,000 U, is followed by an infusion. Adjust according to APTT. In the patient with bleeding diathesis, dialysis without added heparin may be done.

•Check glucose preferably hourly. Normal dialysate fluids do not contain glucose. Dialysate fluids containing glucose should be used, or it should be added when hypoglycemia is anticipated (e.g., in patients with liver dysfunction and sepsis).

Step 7: Assess adequacy of a dialysis session

•Urea reduction ratio: predialysis urea—postdialysis urea/predialysis urea. The target is 65%.

•Kt/V: a dimensionless ratio representing volume of plasma cleared (Kt) divided by the urea distribution volume (V). The latest generation of hemodialysis machines is equipped with this measurement capability. The target is 1.2.

•In clinical practice, postdialysis urea and creatinine are compared with subsequent predialysis levels. A steady state reflects recovering of renal function, and dialysis sessions may be spaced out accordingly.

Step 8: Optimize adequacy of dialysis

•Blood flow rate depends to a large extent on the position and patency of the central venous access catheter used for dialysis.

•Dialysate flow rate can be varied from 300 to 800 mL/min.

•Dialyzer efficiency: a high-efficiency (high mass transfer area coefficient) dialyzer with a thin, large-surface-area membrane, wide pores, and a design, which increases contact between blood and dialysate, will remove more waste products. However, the water used for dialysis in such situations needs to be ultrapure.

•Molecular weight (MW) of solute. Urea (MW 60) will be removed from blood

more efficiently than creatinine (MW 113). Larger molecules like b2-microglob- ulin (MW 11,800) can only be removed by high-flux dialyzers.

•Access recirculation, which depends on the proximity of the “arterial” inflow and venous outflow of the dialysis catheter. Separate tunneled lines cause less recirculation.

•Hypercatabolic patients: high urea nitrogen generation rate from endogenous protein breakdown may give a false impression of “inadequate solute clearance.”

•Residual renal function when present may give an impression of “higher solute clearance.”

•Protein-bound molecules are not well removed by dialysis. Charcoal hemoperfusion is a better alternative.

Step 9: Assess hypotension during dialysis

•Hypotension is the commonest complication during dialysis. It occurs most commonly in intermittent hemodialysis.

•Commonest cause is reduction of intravascular volume due to mismatch of rate of ultrafiltration and tissue refilling.

•Assess central volume status (CVP).

46 Managing a Patient on Dialysis	373

•Look for features of sepsis.

•Look for underlying cardiac dysfunction, anemia, prior intake of antihypertensive medications, arrhythmia (commonly atrial fibrillation), and autonomic neuropathy.

•Acute coronary syndrome, pericardial tamponade, or air embolism may also present as hypotension.

•Dialyzer reaction is rare now, with the use of biocompatible polysulfone membranes.

Step 10: Manage hypotension promptly

•Put the patient in the Trendelenburg position (with airway precaution), stop ultrafiltrate, and connect to a cardiac monitor.

•Do a 12-lead ECG and troponin I if clinical features are suggestive of ischemic heart disease. Do not treat supraventricular tachycardia or atrial fibrillation unless the patient is in shock or arrhythmia persists post-HD.

•A cautious bolus of 100 mL NS or more may be needed, or 25% dextrose if blood glucose is low.

•Check Hb and transfuse if it is less than 8 g/dL.

•Ensure that the dialysate fluid contains bicarbonate and not acetate, as the latter causes more hypotension.

•Dialysate temperature may be lowered to 36.5°C to promote vasoconstriction.

•Reassess the dry weight and restart ultrafiltrate at a slower rate when stable.

•Avoid antihypertensives pre-HD.

•If the patient gets chills or fever, screen for an underlying infection.

Step 11: Monitor for other potential complications (Table 46.2)

•Apart from hypotension, various other local and systemic complications may be seen in a patient on dialysis, which should be assessed and managed promptly.

Table 46.2 Complications	1.	Hypotension
of dialysis	2.	Muscle cramps
	3.	Nausea and vomiting
	4.	Headache
	5.	Chest pain or back pain
	6.	Itching
	7.	Disequilibrium syndrome
	8.	Dialyzer reactions
	9.	Bleedings—gastrointestinal, epistaxis, intracranial
	10.	Seizures
	11.	Hemolysis
	12.	Air embolism
	13.	Visual or hearing loss
	14.	Hypertension
	15.	Hypoglycemia, hypothermia