Question And Answer On Biomedical Engineering

Running head: QUESTION AND ANSWER ON BIOMEDICAL ENGINEERING
Question and answer on biomedical engineering
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QUESTION AND ANSWER ON BIOMEDICAL ENGINEERING1
CHAPTER 8: BLOOD WARMERS
Answer 1:
The purpose of a blood warmer is to heat the blood that passes through it upto body
temperature or 37°C or 98.6°F to maintain temperature of the blood before transfusion into
the recipient. This device is designed specifically for regulation of transfused blood
homeostasis inside the body of patients who are undergoing transfusion. The blood warmer
indicates the temperature of the blood leaving it.
Answer 2:
A blood warmer is used during the replacement of 50% of the blood in the patient or
when the transfusion rate is high. It is also used when the patient is hypothermic or forms
cold agglutinins in case of delivering cold fluid.
Answer 3:
A blood warmer is used when a patient has a risk of developing hypothermia therefore
it is necessary to warm the blood at apropiate temparture. Because blood is kept at the
refrigerator to preserve the cells, the transfusion of the cold blood can bring a state of
hypothermia in the patient which can lead to hemolysis.
Answer 4:
Two common methods used by the blood warmers to warm the blood are heating
blood flowing through a specific fluid set or heating the fluid using IV tubing that surrounds
the blood. In the first case the fluid set is surrounded by the blood warmer’s heater which
produces the heat and warms the fluid set surrounding the blood. Here the blood flowing rate
is limited to maximum rate of flow because the blood warmer cannot warm the blood if it is
flowing very fast. In the second case, the blood warmer directly warms the blood flowing

QUESTION AND ANSWER ON BIOMEDICAL ENGINEERING2
through the IV tubing set that is connected to the patient. A warm solution runs through the
tube that keeps the blood at constant temperature as it continues to flow through it (Poder,
Nonkani, and Leponkouo 2015)
Answer 5:
The common issues faced by the biomed while performing the blood warming process
is problem with the parts of the device such as heating element or the circuit where it fails to
heat the blood or the fluid solution. Other issues include the overheating of the blood leading
to hemolyis if the temperature of the blood is not maintained properly or if the temperatre
alarms regarding the fluctuation of temperature of the blood warmer are not responded by the
biomed.
Answer 6:
The specific tests performed on the blood warmer by the biomed are:
 To inspect the overall status of the blood warmer to check if any parts are broken such
as broken case.
 To ensure that functioning of all the user controls are taking palce properly such as a
button or control of the blood warmer is not functioning properly should be
immediately repaired before placing it for service.
 To check temperate accurately. The biomed compares the blood warmer’s
temperature with the value of calibrated thermometer. If the temperature of the blood
warmer is not accurate as specified by the manufacturer, then the biomed calibrates or
repairs the device. There may be specific test to check the functioning of the blood
warmer that is specified by the manufacturer should be followed by the biomed.
 The blood warmer’s high or low alarm should be operated and checked by following
the instructions given by the manufacturer.

QUESTION AND ANSWER ON BIOMEDICAL ENGINEERING3
 Ensure the electrical safety of the blood warmer such as measurement of the ground
resistance and chassis leakage and the leakage should be minimised.
 A final check is necessary to ensure the functionality or operations of the device
before putting it for service. All the functionsa should work according to the design of
the manufacturer.
 All the tests for the device regarding its performance and repair should be
documented so that it can be retrieved whenever required. The documentation should
contain the valid tests and repairs of all parts of the device within the acceptable limits
of the manufacturers and other authorities. This will avoid any legal issue regarding
the maintainance of the device (Kim et al. 2015).
CHAPTER 8: ELECTROSURGERY
Answer 1
The electrosurgery unit is used by a physiscian enabling them to cut or coagulate the
tissue by using electric currents of high frequency. There are two purposes of the
electrosurgery units which include cutting or coagulating or a combination of both. This is
done by flowing a high frequency oscillating current between the two electrodes through the
tissue of the patient. The frequency fluctuates between 300kHz to 3MHz and power vary
from zero to 400 watts. Th electrosurgery unit forms signal when the output waveform’s duty
cycle varies making a cut or coag or a combination known as the blend mode through the
tissue (Taheri et al. 2014). .
Answer 2
The three modes of the operations are the cut mode, coagulation mode and the blend
mode.

QUESTION AND ANSWER ON BIOMEDICAL ENGINEERING4
 The cut mode performs vaporization of a tissue by mimicking a surgeon who cuts a
tissue with the help of a knife. The duty cycle of the cut mode is 100%. The working
of the cut mode describes how the surgeon uses vapour to cut through the tissue
during which rapid heat is produced. To perform dissection, pure cut is used where
the electrosurgery unit acts as a stainless steel scalpel whee the bleeding is not under
the control of the surgeon.
 In the coagulation mode the tissue is altered from a liquid state to a solid sate thereby
developing a clot at that site. The duty is less than the cut mode that is 30% or below
but the voltage used is high. The coagulation occurs in this mode because less heat is
generated compared to the cut mode. This mode is used by the surgeon to stop the
bleeding and excess loss of the blood by foming coagulum or clot at the site of the
surgery. The coagulation occurs in two ways- one is the pinpoint coagulation which
ceases local bleeding and the other is fulguration in which direct contact is not used
and the current is hops from active electrode to the tissue. Fulguration is uselful in
sealing unseen bleeding from cuts which the surgeons cannot locate or even seal large
bleeding sites.
 Blend mode is the combination of both cut and coagulation mode at the same site. The
duty cycle ranges from 30% to 99%. This mode is used by surgeons to use the cut and
coagulation mode by varying the degree of duty cycle. This mode is standard for
sealing small bleeding sites when the cut occurs in soft tissues (Taheri et al. 2014)..
Answer 3:
The two modes of electrosurgery unit based on the current path are moniopolar and
bipolar. The current flow in monopolar mode occurs between the the electrode present at the
surgical site and the return electrode, the latter is placed on the back, leg or hip of the patient.

QUESTION AND ANSWER ON BIOMEDICAL ENGINEERING5
The return electrode functions to allow flow of safe electric current to the patient. Therefore
the current flow is seen between the return electrode and monopolar handpiece.
On the other hand, a bipolar mode of current flow occurs between two points of the
hand pieces that needs forceps which are specially designed. Another electrode present in the
fulguration hand piece where the current hops or shows sparks in the tissue of the patient. A
patient plate or return electrode is not required in bipolar electrosurgery. The purpose of this
mode is introduce coagulation in the tissue between the electrodes present in hand-piece
(Cordero 2015).
Answer 4:
REM alarm works as a safety check during the monopolar mode of electrosurgery.
The return electrode having a large surface area is sited close to the surgical site and this can
lead to the development of high contact resistance between the patient’s surgical site and the
return electrode. This resistance can cause damage to the skin or burn the skin at the site
where the return elecetrode is placed. To circumvent the damage to skin, the electrosurgery
unit contains an alarm known as return electrode monitor or REM alarm. The purpose of this
circuit in the alarm is to check the increasing contact resistance between return electrode and
the patient’s skin by maintaining a low contact resistance. The output of the electrosurgery
unit is inhibited by this REM if the contact resistance is more than 150 Ohms.
Answer 5:
The cut/coag safety works in maintaining safety for the patient when the physician
presses the hand or foot switches by mistake. This circuit for safety ensures that cut operation
is not functioning when the switches for both cut and coag are down at the same time. When
the physician presses both the hand and the foot switches accidentally, the cutting mode is
didsabled whereas the less damaging mode that is the coagulation mode is enabled.