DIALYSIS MACHINES KEY FEATURESYousaf Khan Renal Dialysis LecturerIPMS-KMU

DIALYSIS MACHINES KEY FEATURES Blood pump Dialysate delivery system Safety monitors Options System disinfection

BLOOD PUMP Circulate the blood through the dialyzer back to the

patient. Peristaltic roller pumps which works by progressive

compressing special segments of the blood tubing are used.

Pump occlusion: occlusion means that the roller compress the tubing segments against the semicircular housing sufficiently to close the lumen completely at that point.

Overocclusion may crack tubing and rupture Occlusion incomplete – back flow

DIALYSATE DELIVERY SYSTEM Appropriate blending of concentrate and water for

preparation of final dialysate. To monitor dialysate for temperature, composition and

blood leak. To control dialysate pressure or ultrafiltration rate. To regulate the dialysate flow rate through the

dialyzer. Deareation of water Provide protective mechanisms to isolate the blood

circuit and the patient from unsafe dialysis. System for disinfection and cleaning.

SAFETY MONITORS Monitors for blood circuit

Arterial pressure monitor Proximal to the blood pump Reads the arterial pressure at the segment between the

pts needle site and proximal to the blood pump which represent the negative pressure created by roller pump.

How much suction is being placed on the arterial wall and guard against excessive suction on the vascular access.

Resistance within the needle It provide an index of vascular access blood supply

relative to the flow demand by the blood pump.

ARTERIAL PRESSURE MONITOR A guide to appropriateness of needle placement or

kink or obstruction in the blood segment between the pts and monitor.

Mechanism: The pressure is monitored by mechanical or electronic

manometers ( pressure transducer). Electronic transducer is more sensitive and have rapid response.

VENOUS PRESSURE MONITOR Just distal to the dialyzer usually attached to the top of

the venous air trap.

Reads the venous pressure at the segment b/w the point after the dialyzer and before the blood return to the pts body.

Represent resistance of the blood returning to the patient via the venous needle.

It may indicate venous stenosis proximal to the needle site.

Mechanism: as in arterial pressure monitor

VENOUS AIR TRAP AND AIR DETECTOR Just distal to venous pressure monitor. Often second air trap on the arterial line is also used.

To prevent air entry into pt or the dialyzer. Mechanism: air bubble enter- sensor reacted through

ultrasonic transducer or light beam by stopping blood pump, clamping the venous line and activation audiovisual alarms.

MONITORS FOR DIALYSIS SOLUTION CIRCUITConductivity: Before dialysate reaches to dialyzer To guard against excessive diluted or concentrated dialysis

solution.

Conductivity meter detects high or low conductivity the machine automatically sounds an alarm and puts the dialysate into bypass mode so that no dialysate flow to the dialyzer.

Exposure of the blood to hyperosmolar dialysate can lead to hypernatremia and other electrolyte disturbances.

Exposure of the blood to hypo osmolar dialysate can lead result in hyponatremia and rapid hemolysis.

Temperature: Before the dialyzer To avoid high temperature Mechanism: through a temperature sensor, high

temperature activate an audiovisual alarm simultaneously with bypass mechanism.

Dialysate pressure or transmembranouse monitor: To monitor the ultrafiltration with an upper limits avoids

excessive level (the usual preset range 0-500 mmHg). Excessive TMP may lead to rupture of the dialyzer and secondary deareation ( cause air accumulation).

Mechanism: the monitor may have automatic or manually set limits so that extrusion outside the limits trigger an audiovisual alarm.

Blood leak detector: In the effluent dialysate line It guards against undetected blood loss during dialysis. A beam of light is directed through a column of dialysate

onto a photoelectric cell. A change in translucence and light scatter in dialysate reduces the light received by the photocell, stopping blood pump and activating audiovisual alarms.

Bypass valve or mechanism: If the conductivity or temperature found to be out of limits a

bypass valve is activated to divert dialysate around the dialyzer directly to the drain.

OPTION IN HEMODIALYSIS MACHINE Heparin pump Bicarbonate Variable sodium Controlled ultrafiltration Programable ultrafiltration Dialysate urea sensor (online kt/v monitor) Single blood pathway

SYSTEM DISINFECTION All dialysis unit must have written policies the deal with the

dialysis fluid pathway and dialysis machine. Disinfection procedure should be done on regular base

according to manufacturer's instruction.

Target: To control bacterial contamination. HIV, HCV and HBV viruses

are known to be inactivated by common household bleach.

Methods: Heat disinfection requires temperature greater than 85-90 C. Chemical disinfection such as formaldehyde, sodium

hydrochloride and acetic acid.

DIALYSIS MACHINE: PATIENT MONITORB.p: Some machine monitor arterial pressure automatically.

ECG: Can be monitored by the machine

Blood volume monitors: Hct or protein conc. In the arterial blood line by optical

or ultrasonic sensors as surrogate for blood volume (as water is removed from the blood, blood volume falls, and red blood cell and protein conc. increase) they can measure relative blood volume reliably and reproducibly and allow automatic feedback.

DIALYSIS MACHINE: PATIENT MONITORMonitoring fluid balance: Blood volume monitor can analyze the effects of a short period of

rapid UF on blood volume to determine the hydration status of a patient.

The rate of refilling of the vascular compartment can give a measure of extravascular fluid.

Access recirculation: Can be measure temperature in the arterial blood line after reducing

or increasing the dialysate temperature for a few minutes.

Access blood flow: Can be measure by saline injection techniques during Hct monitoring

or change in Hct due to a short period of UF.

Delivered Kt/V Online measurement of urea removal or change in dialysate

conductivity

ALARM DURING HEMODIALYSISPROBLEM SOLVING GUIDE LINES When an alarm is activated during dialysis do

the following Identify which alarm has been activated Identify the cause Correct the cause Resume dialysis if safe to do so

Power: Turn the system off and on: if still no power check the power

cord make sure power is available. Check the fuse.

Arterial and Venous Pressure: Check to see that blood pump is running and connected

properly Check to see if blood flow rate has changed Determine if patient has coughed or moved Check to see if the monitor line is leaking Check the blood line for kinks or leaks Ensure the monitoring lines are connected to proper drip

chambers

High venous pressure: Manipulate the needle and or the line. If access is small a

tourniquet must be used, being certain the blood pump is off, recantation with new needle if needed.

Adjust the blood flow rate, proper heparnization, treat access problem and proper needle and needling.

Extreme care must be exercised when dialyzing a patient with high venous pressure

This increase the baseline TMP and obligatory ultrafiltration will occur.

Single needle device is occasionally impossible to use, because with high venous pressure, venous return will be impaired and blood recirculation will be high.

High negative pressure: Manipulation of the arterial needle is similar to that of

venous needle. In most cases the needle may have to be replaced with the same precaution as with venous needle.

Treat the cause Proper needling Asses the access

High positive dialysate pressure alarm: Check to see if drain is occluded or kinked Check to see if dialysate hoses are leaking

Low negative dialysate pressure alarm: Check to see if dialysate hoses are kinked

Air Detector alarm: Check for air leaks around tubing joints Excessive undetected negative pressure Check for unattended intravenous solution administration.

Management of air embolism if present. Clamp the venous line and stop the blood pump. Place the patient in trendelenberg position on the left side with

the chest and head tilted downward to trap the air at the apex of right ventricle away from the outflow tract.

Cardiorespiratory support oxygen 100%. Occasionally percutaneous aspiration of the air foam from the

heart may be necessary.

High temperature alarm: Determine temperature of dialysate in the line actually high Check to ensure incoming water temperature is below 90 F.

Low Temperature alarm: Determine temperature of dialysate to dialyzer in the line is

actually low. Turn the mode selector switch to dialyzer Allow adequate time for the system to stabilize and come to

proper temperature range. Check to ensure incoming water temperature is above 40 F.

High Conductivity alarm: Check to see if water is flowing too slowly or turn off. Check for kink in the concentrate out line. Make sure that the system has had time to stabilize Analyze the dialysate to confirm high conductivity at the to

dialyzer line connection:

a. If normal there is malfunction in the machine itself (change it)b. If high again concentrate before resuming dialysis.c. Be certain that the dialysate flow rate is proper.

Low conductivity alarm: Turn the mode selector switch to dialyze. Connect the concentrate line to the system Drop the concentrate line into the concentrate container Check for kinks in the concentrate in line Make sure the filter on the concentrate in is clean Allow adequate time for the system to stabilize Change the concentrate container if it is dry If the concentrate container has not run dry a sample of dialysate

should sent to the laboratory for sodium and chloride. Analyze the dialysate to conform low conductivity at drain If low conductivity is conformed change the concentrate bottle.

If the conductivity still low after changing the concentrate a different machine should be tried.

Be certain that the dialysate flow rate is proper.

Blood leak alarm: make sure the blood leak detector is clean Check the effluent for traces of blood Exclude Bilirubin in dialysate in jaundiced patient, Air bubbles in dialysate,

Dirty sensor If leak confirmed and you can not mange the cause Reduce dialysate compartment pressure to -50 mmHg to avoid

bacterial entry to the blood Dicontinoue dialysis

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