Dialysis Machine.

DIALYSIS

A normal kidney performs both filtration and cleaning process in the human body. It filters the impurities from the blood and removes extra toxins, excess water and other chemicals from the body. The kidney also helps in regulating blood pressure and other elements like sodium, potassium and bicarbonate in the body. It also provides vitamin D.

Dialysis is a procedure carried out in individuals having kidney failure (i.e a condition in which the kidney’s ability to remove toxins and excess fluid from the body fails). This procedure uses a machine to remove excess waste, fluids and salt from the body and to keep the patient’s body in balance.

Types of Dialysis

There are two types of dialysis

1. Hemodialysis 
2. Peritoneal dialysis

Hemodialysis

Hemodialysis is the most commonly used method. This consists of an artificial kidney (dialyser) which removes wastes and excess fluids from the blood. During hemodialysis, the surgeon performs an operation to remove the blood from the patient’s body and allow it to enter into the dialysis machine. This artificial kidney purifies the blood and it is then returned back to the body.

Arteriovenous (AV) fistula is most commonly preferred for long term treatments. AV fistula is a surgical connection made between the artery and vein. Impure blood is removed from the surgical site through a catheter for filtration and purified blood is entered into the body.

If the blood vessel does not support adequate blood flow, then the surgeon connects a plastic tube or catheter for easier flow of blood. This type is known as the AV graft. Another method called vascular access catheter is also performed. In this method, the catheter is inserted into the large vein in the neck. The process of hemodialysis lasts up to 3 to 5 hours and it is done three times per week. It also depends upon the patient’s condition on how much waste is accumulated in the body. Patient’s must undergo hemodialysis in hospitals and dialysis centres.

Peritoneal Dialysis

Peritoneal dialysis can be performed by the individual at home. It consists of a dialysate, catheter and a drainage bag. The catheter is inserted into the peritoneum (a membrane covering the abdomen). 

Dialysate is then passed through the catheter and it enters the abdomen. This dialysate absorbs excess waste and fluids from the blood and then it is allowed to drain. It gets collected in the drainage bag. This process takes only a few hours and is done five to six times a day. One can undergo this method even when sleeping or walking. Peritoneal dialysis is done to patients having acute renal failure which lasts up to a short span of time and recovers automatically.

Peritoneal dialysis is otherwise performed in three ways:-

1. Continuous ambulatory peritoneal dialysis (CAPD) – This method is performed several times a day. During this process, the patient must be awake. This method does not need any machine.

2. Continuous cycling peritoneal dialysis (CCPD) – In this method, a machine is used for sending the dialysate into the peritoneum and also for removing the drainage from the abdominal cavity. This must be performed only when the patient falls asleep.

3. Intermittent peritoneal dialysis (IPD) – This is similar to CCPD, but it takes a longer time and is performed in the hospital.

Risks of Hemodialysis:-

• It causes low blood pressure
• Anaemia
• Difficulty in sleeping
• Muscle cramps
• Bloodstream infections or sepsis

Risks of Peritoneal Dialysis:-

• A weakening of abdominal muscles
• Hernia
• Stomach pain
• Infections in the abdominal cavity

Deciding to Stop Dialysis

Before the conclusion, one must discuss with the doctor about stopping dialysis that he/she is undergoing. Without proper advice from the surgeon, one must not come to the conclusion because it may cause any serious harm.

Dialysis Machine

A Dialysis machine is a therapeutic device used in the process of dialysis for removing excess waste and for purifying the blood. Blood is removed from the patient’s body and is allowed to enter the dialyser (artificial kidney) in the machine. An anticoagulant (heparin injection) is present in order to prevent the blood from clotting. The dialyser is a semipermeable membrane which consists of dialysate( a mixture of water and electrolytes). Blood is purified in the dialyser and is pumped back to the body. Excess amount of urea and salt from the blood is removed by the dialyser. 

The dialysate maintains the blood at a particular temperature. This is because a higher temperature will damage the blood components. 

If the temperature rises in the machine, safety cut valve is used to switch off the heater. However, before allowing the blood to enter into the patient body, the blood is warmed by the heater. Therefore, the temperature is maintained between 36 – 42 degree Celsius. For controlling the temperature in the machine, it consists of a thermostat and a proportional controller. 

This controls the power given to the heater. Pressure in the dialysis is monitored by the transducer. Negative pressure in the dialysate is created by the effluent pump. Therefore, if pressure raises, the effluent pump goes off. Dialysis machine also consists of a blood leak detector to monitor any leakage in the tubings or any other part of the machine. After completing the purification process, the used dialysate enters into the waste-collecting tank. Purified blood passes through the patient body.

Principle of Dialysis

The main principle of dialysis is based on diffusion and ultrafiltration. 

In Diffusion, fluid flows from high concentration to low concentration through a semi-permeable membrane. In this process, impurities from blood diffuse into the dialysate, whereas electrolytes and other minerals diffuse into the blood from the dialysate. Therefore, purified blood is allowed to enter into the body and the dialysate is pumped out.

Ultrafiltration is the process of removing excess fluid from the body from positive to a negative pressure gradient (i.e high to low pressure). Here, blood comes under positive pressure, dialysate come under negative pressure.

Components& Functions of the Dialysis Machine.

• Blood Pump & Tubings – A blood pump is used to pump blood from the body to the dialysis machine

• Syringe – A drug called heparin is used in the injection. This is used to prevent blood clotting.

• Dialyser – Dialyser is also known as an artificial kidney. It is filled with a combination of water and electrolytes called dialysate. In this dialyser, blood is filtered and purified.

• Pressure Monitor – Arterial pressure monitor: This is used to detect the pressure between the blood coming from AV fistula and blood pump.

• Venous Pressure Monitor - This part usually measures positive pressure in the system. Low blood flow or any other disconnection in the circuit represents low venous pressure.

• Sensors – Sensors are used for monitoring various parameters in the circuit. This includes parameters like blood pressure, dialyser pressure gradient, temperature, Oxygen saturation etc.

• Air Detector – Air detector is used near the venous pressure line. This is used to detect any air leakage or the presence of any air molecules in the blood entering the patient’s body.

• Alarms – Alarms are used to prevent errors occurring in the functioning of the machine. This is used to detect blood flow, blood pressure, temperature, a mixture of dialysate.

Hemodialysis Catheter

A hemodialysis catheter is used to exchange blood from the patient to the dialysis machine. The catheter is of two types: with cuff and without a cuff. Catheter without cuff is used only for a shorter time (in peritoneal dialysis). The catheter consists of two openings. Red coloured opening indicates removing of arterial blood from the patient’s body into the machine. Blue colour indicates venous opening where purified blood is allowed to pass through the patient.

How to Prepare for Hemodialysis:-

Before performing dialysis treatment, the surgeon advises the patient to undergo a minor surgery called AV fistula or AV graft. This surgery is done before 3 to 4 weeks prior to the dialysis treatment. The time is given to heal the operated site. Vital functions of the patient’s body are also monitored during the treatment. They will monitor the height, weight, body temperature and other chronic conditions like blood pressure and diabetes are measured.

What Happens if There is a Power Failure During Dialysis:-

During a power failure, the dialysis machine stops working. Lights will turn OFF, and an alarm indicates power failure in the machine. The blood pump is operated by hand either to return the blood immediately or to keep the blood in circulation (incase if the machine gets power soon.) Once the blood is returned to the patient, the circuit must be disconnected. And the surgeon will ask the patient to come for another day. If the power is ON immediately after a power cut, the system will be able to resume the filtration process.

Problems and Troubleshooting:-

• Be sure to keep the machine clean and safe. Thoroughly clean the droplets, stains of blood as soon as possible to prevent infections.

• The person may be infected when operating the machine. So be careful when handling disposable products.

• Be sure the water, dialysate concentrate is good in quality in order to enhance performance and safety.

• Confirm whether all cable connections are correct and safe to prevent electric shocks.

• Do not operate the machine with wet or bare hands. Always use gloves to prevent infections.

Maintenance:-

• Calibration must be done regularly to the dialysate pump and blood pump.

• Preventive maintenance should be done to avoid equipment breakdown.

• Accurate timing must be maintained for ultrafiltration rate.

• Clean and disinfect the machine after using on each patient.

• Clean the machine from top to bottom using disinfectant cloths/wipes.

• Install the machine in a place where it is free from moisture 

• Check the power supply

• Check the earth connections properly

Risks and Troubleshooting

Troubleshooting the machine should be done by qualified personnel.

👉 Watch Dialysis Machine Video from OurYouTube Channel Bolew:-

Article Prepared By:-

       

 👉 Sumitha Ramadass

    

Reference

• https://www.healthline.com/health/dialysis#purpose
• https://www.kidney.org/atoz/content/dialysisinfo
• https://www.webmd.com/a-to-z-guides/kidney-dialysis#1
• https://www.pharmaceutical-journal.com/cpd-and-learning/cpd-article/dialysis-principles-and-treatment-options/20068038.cpdarticle?firstPass=false
• https://www.nephroxenia.com/de/post/1/aytologh-arthrioflebikh-anastomwsh
• https://www.nikkiso.com/products/medical/dialysis.html
• https://www.donate4hassan.org/blog/2018/8/20/peritoneal-dialysis-at-home
• https://www.assignmenthelp.net/assignment_help/principle-of-dialysis
• https://www.freseniuskidneycare.com/ckd-treatment/what-is-dialysis/hemodialysis-machine
• https://www.slideshare.net/tejabayapalli/hemodialysis-machine-62992148
• http://www.bcrenalagency.ca/resource-gallery/Documents/Cleaning%20and%20Disinfecting%20Hemodialysis%20Machines%20and%20Stations.pdf
• http://www.sjkdt.org/article.asp?issn=1319-2442;year=2009;volume=20;issue=1;spage=49;epage=56;aulast=Azar#:~:text=Routine%20preventative%20and%20annual%20maintenance,significantly%20impact%20adequacy%20over%20time.
• http://www.frankshospitalworkshop.com/equipment/documents/dialysis_units/service_manuals/Nipro%20Diamax%20Dialysis%20Machine%20-%20Service%20manual.pdf
• https://www.indiamart.com/meditech-devices-private-limited/meditech-dialysis-catheters.html
• https://www.kidney.org/atoz/content/hemocatheter
• https://science.howstuffworks.com/innovation/everyday-innovations/question17.htm
• https://www.slideshare.net/tejabayapalli/hemodialysis-62992175

Electro Surgical Unit (ESU).

Electrosurgery. 

Definition:- 

Electrosurgery is a procedure involved in cutting and coagulation of biological tissues. This procedure uses high frequency alternating electrical current. This is also used for dissection, fulguration (removal of abnormal tissue growth), and for shrinking tissues.

Principles of Electrosurgery.

The main principle of electrosurgery is that it uses an alternating (AC) electric current at high frequency or radiofrequency. The frequency ranges from 100KHz to 5 MHz. This current is passed through the patient’s body and produces the heat. Therefore, the surgical procedure is performed using an electrode and it is controlled either by a hand switch or footswitch.

Another procedure called Electrocautery is related to Electrosurgery. But in electrocautery, it uses direct current (DC) and heat is generated in the circuit, not in the patient’s body. Electrocautery is also known as thermal cautery. This procedure uses heated metal wire electrode for tissue destruction (i.e either to remove or coagulate the damaged tissue). As we all know, the movement of electrons is called electric current. In Direct current, electrons flow in the same direction. In Alternating current, the flow of electrons changes periodically.

Modes of Electro-surgery:

Monopolar Electrosurgery vs Bipolar Electrosurgery.

In Monopolar Electrosurgery, it consists of an electrosurgical generator, active electrode, patient and patient return electrode. During operation, the patient plate is attached to any part of the patient’s body. Electric current is generated from the electrosurgery generator and it passes through the active electrode where it creates heat in the tissue as well as the entire body cavity. And it returns back to the generator through the patient return electrode.

Monopolar is used to cut, coagulate, desiccate tissues. This is the most commonly used method in electrosurgery.

In Bipolar Electrosurgery, the bi-forceps electrode is used. The forceps perform both the active and return electrode function. Forceps are used for grabbing the tissue and the electric current passes through the forceps to the respective area in the tissue. 

Therefore this prevents further damage to other body parts and prevents the patient from any burns. Bipolar surgery uses only less voltage and hence it is not used for cutting and coagulation of larger bleeding tissues. Bipolar surgery is recommended in patients with implanted devices to prevent them from short circuit.

Types of Electrosurgical Technique:-

• Electrocoagulation
• Electrodesiccation
• Electrofulgaration
• Electrocution

These techniques are used for destroying abnormal or damaged tissues. Also used to prevent loss of blood while performing the surgery.

Types of Current:-

There are three types of current used in electrosurgery

• CUTTING – Cutting current is a continuous sinusoidal waveform. The power of cutting current must be maintained between 50W and 80W. The surgeon holds the electrode slightly away from the tissue to create a spark for cutting. This spark creates heat in the tissue area.

• COAGULATION – Coagulation current is an interrupted and damped sine waveform. The waveforms have high peak voltages. Due to this, the temperature also increases causing thermal destruction in the tissues. Therefore, coagulating current is used for coagulation in bleeding vessels/tissues.

• BLENDING –Blend current has a combination of both cutting and coagulating current waveform. This is also a modified form of cutting current. This blending current is used in hemostasis of tissues. Blend current produces a higher peak to peak voltages. Therefore, the duty cycle also changes between the burst current and coagulation. For maintaining the same directional flow, this blend current can be rectified. Surgeries like dental and dermatology use rectified current.

Tissue Effects of Electrosurgery

• Vapourisation – Vapourisation of tissue is achieved by producing heat in the tissue. Heat is produced by creating a spark in the surgical area with the help of the electrode. During surgery, the surgeon creates a minimum spark over the tissue. Due to sparking, the maximum current can be produced.

• Fulguration –Fulgaration is a combination of sparking with coagulation. This creates longer sparks in the tissue. In this process, less heat is produced in the tissue. That is why coagulation takes place rather than vapourisation.

• Dessication – Desiccation is produced by low current density and high voltages. This is the modification of coagulation. In this procedure, the electrode is used directly in contact with the tissue, which converts the electrical energy into heat, which causes the cells to shrink. 

Electrosurgical Unit 

Electrosurgical unit is a device used in electrosurgery for cutting, coagulation, fulguration, and desiccation of tissues. Electrosurgical unit is used in surgeries to prevent blood loss. ESU consists of an electrosurgical generator with one or more electrodes and a patient return electrode. This unit is controlled using a hand switch or a footswitch.

The Electrosurgical Generator produces different waveforms corresponding to the tissue effects. 

The Active Electrode is placed directly in the surgical area and the patient Return Electrode is kept in any part of the patient body.

The electrosurgical unit creates an electric current to pass through the electrode and produces heat in the tissue for cutting, coagulating and removing damaged tissues. It is operated under two modes: Monopolar and Bipolar.

In monopolar mode, there is an active electrode which carries the current to the tissue and a patient return electrode for taking back the current from the tissue. In bipolar mode, it uses the forceps type of an electrode which performs both active and return operations.

Electrosurgery is often similar to diathermy. Diathermy uses an electromagnetic current to produce heat. It uses dielectric poles. Diathermy passes electromagnetic waves and thus heat is generated in the body. The generated heat increases blood flow in the area causing pain. This is most commonly used in muscle and joint problems for allowing free blood flow. 

There are three types of Diathermy. This includes:- 

• Shortwave diathermy – High-frequency electromagnetic current is used to generate heat in the tissue. This is used to treat pains that occur during kidney stones.

• Microwave diathermy – Microwaves are used to generate heat in the body. Microwaves cannot penetrate deep into the muscles.

• Ultrasound diathermy – This uses sound waves by causing vibration in the tissues. This is used to treat deeper tissue areas.

Types of Electrodes

1. Needle electrode
2. Blade electrode
3. Wire loop electrode (used for cutting)
4. Electrosurgical forceps
5. Angular electrode

Block Diagram of ESU :

High-frequency power is required to generate heat from the waveform generator. Different waveforms like cutting, coagulation and blending are also produced from the generator. The mode selector is used for selecting which type of mode should be used while performing the surgery. Power level control determines the power applied to the electrodes during surgery.  Alarm circuit is used for creating safety alarms whether the electrodes are attached properly in the patient circuit. 

Circuit Components

The front panel consists of:- 

Power ON/OFF switch – Turning On/ Off of the electrosurgical unit. 

Mode selector – For selecting the modes for performing surgery (CUT mode, COAG mode, BLEND mode ). Cut mode indicates a yellow colour, whereas Coagulation mode indicates a blue colour. 

Fault indicator switch – This indicates poor contact of patient return electrode with the patient by producing alarm. Three-pin switch for monopolar use only hand switch. Three-pin switch for bipolar can be activated with or without footswitch. There is also a two-pin connector for the patient return electrode.

Rear panel Consists of:-

Footswitch control – This is for connecting the footswitch. 

The volume control knob - is used for controlling the audio volume during cutting, coagulation or blending. Power cord connection.

Safety precautions

• Electrosurgery must be performed by specially trained technicians in electrosurgical technologies.
• Electrosurgery should not be performed in oxygen-rich environments because it may easily catch fire and cause serious burns. 
• Before operating, insulation of the electrode must be checked carefully to avoid thermal injuries. 
• Do not activate the equipment in an open circuit.

Do’s

• Electrodes should be placed in clean, dry areas

• Use only insulated electrodes

• Electrodes must be placed in well-cleaned holster, when not in use

• Electrode tips must be cleaned properly.

• Use only low voltage waveforms while operating

• Bipolar electrosurgery can be performed when necessary

Don’ts

• One should not use the electrode in the presence of flame causing agents like (alcohol, tincture etc.) to avoid burns and fire.
• Electrodes should not be wrapped around metal instruments because they cause burns.
• Rubber catheters should not be used in electrode tips.
• One should not operate the electrosurgical unit by standing on a wet surface to prevent them from shocks.
• Surgeons or technicians must not perform the operation with wet hands/wet gloves to prevent electric shock.
• Must wear surgical masks during surgery to avoid smoking difficulties which may cause breathing problems.
• Avoid using the electrode near electric devices.
• Do not use the equipment in patients prior to testing. 

Problems in ESU

• If surgery is performed in oxygen-rich environments, it may cause a surgical fire.

• Patient burns may also be caused by detachment of the electrode pad.

• Incorrect placement of the electrode may also cause burns.

• Electrosurgical injury occurs when the electrode comes in contact with non-target tissue.

• Since the device uses high current, it may cause electric shock, the transmission of infection etc.

• Direct skin contact will cause burns.

Preventive Maintenance

• Regular testing of the equipment should be done to prevent any harm and to enhance patient and staff safety. 
• The person handling the equipment must be well trained by the manufacturer.
• He/She must follow the instructions given in the manual. 
• The technician must carefully inspect the insulation. 
• Lower power setting must be used when starting the equipment for use.

Risks of Electrosurgery

• Most of the risks are caused by thermal injuries. This is mainly due to unintended contact of the active electrode with any part of the body tissues. 
• Another kind of thermal injury is caused by the contact of the active electrode with metal instruments.
• Injuries caused by smoke also causes breathing problems in both patients and surgeons.
• Major risks are associated with respiratory illness and irritation in the eyes, skin etc.
• Therefore, proper measures must be taken before handling the equipment during surgery.

Electrical safety

• The proper power cord must be used. It must be properly grounded.
• Use only proper fuses which have correct voltage and current rating.

Patient Safety

• Proper contact must be maintained between the patient and other metal parts to avoid burns.

• Patient electrode must be connected in order to avoid skin injuries.

• Ensure the connections made do not affect the blood supply in the patient.

Clinical Applications

• Electrosurgery is often used in most of the operations involving tissue surgeries
• ENT (To control nose bleeding)
• Gynaecology
• Ophthalmic surgery
• Dermatology (To remove abnormal skin growth, moles etc.)
• To remove lesions, hair follicles.
• Also used in surgeries associated with organs like liver, spleen, kidneys and heart surgery.

Environments of use

Electrosurgery is used in operating rooms in the hospital while performing surgeries.

Troubleshooting

• Check Electrosurgical unit for any physical damage
• Ensure all cables, electrodes, power cord is connected properly
• Check the power cord properly or immediately replace it.
• Pin connections and switches must be properly checked. If any damage is found, it must be replaced immediately.

👉 Watch ESU Video on Our YouTube Channel Below:- 

Article Prepared By:-

👉 Sumitha Ramadass

References

• https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3407433/#:~:text=Principles%20of%20Electrosurgery,Often%20%E2%80%9Celectrocautery%E2%80%9D%20is&text=Electrocautery%20refers%20to%20direct%20current,alternating%20current%20(Figure%201).&text=Electrical%20current%20flows%20when%20electrons,produced%20when%20electrons%20encounter%20resistance.
• http://www.boviemedical.com/2016/10/03/bipolar-electrosurgery-vs-monopolar-electrosurgery/
• https://www.asit.org/assets/documents/Prinicpals_in_electrosurgery.pdf
• https://www.glowm.com/section_view/heading/electrosurgery-principles-biologic-effects-and-results-in-female-reproductivesurgery/item/21#:~:text=There%20are%20three%20basic%20types,%2C%20nonmodulated%20sinusoidal%20waveform%20(Fig.
• https://veteriankey.com/surgical-modalities-laser-radiofrequency-ultrasonic-and-electrosurgery/
• https://www.semanticscholar.org/paper/Electrosurgery%3A-principles-and-practice-to-reduce-Brill/ba1a6e6b411cba18601762375b62562cdf166677/figure/5
• https://www.uptodate.com/contents/overview-of-electrosurgery
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• https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4579996/#:~:text=An%20electrosurgical%20unit%20(ESU)%20consists,do%20the%20corresponding%20tissue%20effects.
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• https://docplayer.net/21481453-Instructions-electrosurgical-unit-psd-30.html