Lecture 5 Part 1

Question 1

why do we need incubators?

Answer 1

Used to establish and maintain an environment suitable for a neonate
Usually preterm babies but also ill full term

Question 2

What is the back story to incubators?
When was it first developed, why, how, the beginning

Answer 2

Paris in 1880
hypothermia was known to be the primary cause of death for premature infants
French obstetrician Stephane Tarniers first design housed several infants heated over a hot water reservoir
A redefined design followed, a single occupancy incubator heated via hot water- water bottles replaced manually every 3 hours

Question 3

Tell the technological development through the years

Answer 3

1889 design - thermostat regulated heater and forced ventilation

1980 - mercury thermometers

Question 4

Does a modern incubator design have an IEC standard? If so what does it cover?

Answer 4

Yes
Electrical, thermal, mechanical safety
Construction
Materials
Labelling
User instructions

Question 5

what are the key design considerations for an incubator?

Answer 5

Precise control over the environment - temperature, humidity

A quiet environment for the patient - 60dBA within the incubator
Loud noises have been linked with apnoea, hypoxaemia, reduced oxygen saturation, elevated heart and respiratory rates, among other things

Safe for patients - good design, warning alarms, battery backup etc

Question 6

In terms of temperature control, how does the incubator work?
What does the heating system consist of?

Answer 6

Electrical element under the incubator compartment
Heat is provided by convection - air is passed through the heating element by a fan
Temperature can be set within a range, varies typically 28 to 40C which is the air temperature, this is a clinical decision

Question 7

How does the temperature control work in an incubator?

Answer 7

The unit is required to maintain a constant temperature
Can be achieved by a negative feedback control loop
Temperature measurements made using one or more air temperature sensors

Question 8

What are the design variations for temperature control?

Answer 8

Single air temperature sensor is a simple, effective design
Uniformity of temp, multiple air temp sensors can provide a more accurate indication, or fans ensures uniformity of air temperature
Patient skin temperature for the value to be compared with the reference (operator set) temp, requires body temperature to be used on the patient
Equilibrium temperature is reached when the patient reaches the reference (operator set) temperature

Question 9

Temperature control can be hard to maintain, what are the external influences for this?
Heating
Why is this an issue?

Answer 9

There are other sources of heating for the incubator:
Sunlight
Heat lamps
Spot lamps
Electric cushions

Whilst the negative feedback loop will correct, as these are unexpected and unpredictable, variations will increase

Question 10

For temperature control, how does the safety features work?

Answer 10

A redundant system (extra backups) takes the absolute measured temperature and initiates an external audible and visible alarm if this is not within the range. Good as it prevents significant risks to the patient

The system an automatically switch off heating element if the temp is too high

At first switch on, the temp may take more than half an hour to reach the ref temp

Question 11

Humidity is important to control for an incubator, why is it important to control?

Answer 11

The heated air in the incubator will become very dry therefore the patient will experience increased heat loss due to evaporation, this can lead to them becoming hypothermic regardless of the incubator air temp

Question 12

The desired humidity level is a clinical decision, what impacts this?

Answer 12

Patient gestational period

Patient sodium level

Question 13

What are the typical values for humidity control levels in a percentage?

Answer 13

70-80%

Question 14

How is the humidity level actually achieved?
How does it vary?

Answer 14

Pushing the heated air through steam generated from a water tank before it goes through the incubator chamber

Varied by applying a variable temp to the element in the water tank

Question 15

Mechanical components are very important when designing an incubator, how do doors/hatches impact the environment? What is important to consider? What can be done to prevent?

Answer 15

Any door will lead to a loss of environment
Use of the smallest door consistent with the clinical task helps maintain the environment
Often a double wall design to improve heat retention within the incubator
Full removable for cleaning and disinfection
Easy to open, consideration given to one handed function
Provided in a variety of sizes for flexibility

Question 16

The bed tilt is a mechanical component which is advantageous for an incubator, why is this clinically desirable? And what must it need to do?

Answer 16

Demonstrable effects on the cerebral blood flow velocity and the oxygenation, heart rate and blood pressure
Clinical effect is dependent upon tilt angle, an incubator should support a range of options
Tilt can be applied at either end of the couch
Tilt can be manually (via hand wheel) or electronically controlled
Tilt support must be designed to withstand maximum patient weight for the incubator

Question 17

The working height is a mechanical component feature which is important and desirable for incubators. Why is this helpful? How is it controlled? What must be taken into account?

Answer 17

Many members of staff to provide care so must be accessible for all staff
Safer for staff using peripheral aid

Controlled via electric motor and telescopic columns

Maximum height and the effect on the units centre of gravity (must never be at risk for tipping) must be taken into account
Also the effect of variable height on all cables and connections - must be sufficient length and kept tidy so as not to be trapped

Question 18

Base/wheels/brakes are mechanical components which are important for the design of incubators, how and why is it? And what is a downfall of this?

Answer 18

Ensures stability - Wide base, low centre of gravity
Manipulation of the patient or within the incubator compartment exerts force on the incubator that could cause it to move, unexpected movement can be detrimental to the patient
Brakes must be effective, efficacy must be monitored throughout equipment lifetime

Question 19

The mattress is a mechanical component important for an incubator. What is it made of? What are the benefits?

Answer 19

Typically made of polyurethane foam - strong, durable, offers support for the patient, pressure relief, patient may be lying on it for a long time

Vacuum mattress - pressed into any shape and will retain this shape after evacuation. Particularly effective where it is necessary to hold the patient in an extreme or unusual position for their treatment

Often used in combination with barrier bedding - acts as a barrier to pathogens and allergens as bedding becomes contaminated

Question 20

The air filter is a mechanical component which is very important for a good design for an incubator. What does it exactly do? And how does it work? How often is the filter changed to maintain its efficiency

Answer 20

Removes airborne bacteria and other impurities (dust) that would end up in the incubator carried by the outside air

The core of the filter is sealed inside a water repellent, hypoallergenic membrane which only allows air through
Baterial filtration is very high
Regular changes (months) for replacement

Question 21

Scales are a useful mechanical component. Where are they placed? Why is it important? How can the accuracy be verified?

Answer 21

Base of the incubator compartment, on which the mattress and patient lies

Needed to record the patients weight at any time for regular monitoring for this patient cohort

Can be verified using a set of calibrated scales, many companies offer the calibration, it must be traceable to a national lab standard. For the UK they use UKAS for the service

Question 22

How does X-rays work for an incubator, if the neonate needs one? Are X-rays needed?

Answer 22

Has an X-ray drawer which means the patient doesn’t need to move

Frequent and required to monitor the physical development and disease progression

Question 23

Why was the X-ray drawer introduced instead of physically handling the neonate for the X-rays? What is the conflicts here?

Answer 23

NICU staff were unhappy about the patient being handled
Radiology staff concerned and Unhappy about the images becáis of the artefacts caused by the detector being in a tray
Unhappy about the increased patient radiation dose

Positioning and set up significantly affects the radiation dose received and the quality of the image

Good imaging and minimal dose is desired

Question 24

What was found due to using the detector tray and foam mattress during an X-ray drawer scan?

Answer 24

Detector tray - causes the image to appear slightly larger which could affect how the image is read

Memory foam mattress - creates unclear spots or distortion (artefacts) in the image, making it harder to interpret

Question 25

The X-ray drawer needs to be assessed due to the pros and cons of it. The team must make the decision to use it or not. What do they need to take into account?

Answer 25

Risk to the patient being moved
Risk to patient from increased exposure
Risk to patient with magnification and artefacts leading to potential misdiagnosis/missed pathology
Regulation compliance issue - all radiation does to be As Low As Reasonably Practicable (ALARP)
Decision to be made by relevant parties with the info ,
Decisions to be documented

Question 26

What peripheral components are needed to be considered for an incubator?

Answer 26

Oxygen
Blue light
Glucose
IV medication

Question 27

Why is oxygen an important peripheral component that must be considered? And why?

Answer 27

Frequently used
Patients with heart/lung problems need to breathe an increased concentration of oxygen to achieve normal levels of oxygen in their blood
Must be carefully managed - too much oxygen can lead to damage to the eyes and brain

Question 28

What are the ways to administer oxygen to the neonate?

Answer 28

Incubator flooding
Oxygen hood
Nasal cannula

Question 29

Explain how the incubator flooding works

Answer 29

Incubator has a valve that allows connection to a pipe connected to a medical gas pipe line system or oxygen system
Flow of oxygen goes directly to the incubator
Supply comes via oxygen flowmeter - measures flow in real time, manufacturer will have supplied data correlating to oxygen levels in the incubator to flow rate, incubator specifics

Question 30

Explain how the oxygen hood works

Answer 30

Plastic dome placed over patients head, with oxygen inside
Still required to be connected to medical gas pipeline system or an oxygen cylinder.
Still needs to be controlled by an oxygen flow meter
Doesn’t have an effect on temperature and humidity
Can require regular readjustments to cope with movement of patient
Leakage must be a accounted for given the design of the hood

Question 31

How does the nasal cannula work?

Answer 31

Thin plastic tube with soft prongs that can be inserted into the patients nose
Deliver through tube
Oxygen lost at the side so patient may not receive enough oxygen from this delivery system - consider how narrow the tube is, oxygen flow is limited
Connected to gas line

Question 32

Vital signs monitors are a peripheral component for the incubator. Why is it needed and what is needed?

Answer 32

Patients require constant monitoring
Some incubators have it built in and integrated
Wiring must be able to reach from the vital signs monitor to the patient
Attachments must account for the additional weight the monitor adds to the unit

Question 33

Why is bronchial suction a necessary peripheral component?

Answer 33

For patients who have excessive respiratory tract secretions that they are unable to clear themselves
A clinical decision to make, indications include breathing difficulties, changed respiratory rate, decreased oxygen saturation, increased oxygen demand, patient making efforts themselves to clear their airways
Can often associate with a change in patient position ( secretions become loosened)
Oxygen must be available to counteract hypoxia caused by suctioning
Suction catheters placed down the throat, suctions in 5-10 bursts, pressure: 60-120mmHg, as low as is effective

Question 34

Infusion stand is a peripheral component needed for an incubator. Why is it required for the patient?

Answer 34

For glucose, potassium chloride, sodium chloride, blood, IV medication (antibiotics)
Makes it easier and safer to deliver in medication
Option on most incubators
Extra weight for good design for catheter placement etc

Question 35

Do all incubator have built in blue light?

Answer 35

Not all just some

Question 36

what happens to the leakage current in the incubator? what is touch leakage current? How would you measure this?

Answer 36

Leakage current - unintended flow of electrical current that does not follow the intended path.
Unwanted flow of current from the device to the ground, which could indicate an issue with insulating or grounding. Instead of flowing in through the normal circuit, this takes the path of least resistance and flows from the device to the earth.
To measure this, can use a leakage current clamp ammeter or multimeter

Touch leakage current is basically the same but current from a poorly grounded device that would flow through someone touch in the device casing

Question 37

How does the battery back up work? why is it important?

Answer 37

Hospitals are designed such that a loss of mains power to critical equipment is compensated for by power generated by on site diesel generators
It is unlikely that the battery would be relied on for long
Electrical infrastructure companies always prioritise hospitals

Any failure of mains power would result in the loss of the ability to maintain the environment.
Loss of temp could have a significant clinical detriment
Battery can maintain the environment for hours

Question 38

why is it important to have warnings and alarms on the incubator?

Answer 38

A failure of any feature on the incubator operation could have a negative clinical effect on the patient

Question 39

how does the warnings and alarms work for the incubator? What things can be triggered?

Answer 39

Failure of an essential function will trigger a continuous tone alarm

Malfunction of the incubator control module
Mains failure
Air temp sensor failure
Fan failure

Anything not working should be reported immediately to staff

Question 40

how are incubators tested? What parameters can it measure?

Answer 40

Using an incubator testing device

Air temperature
Skin temperature
Temperature uniformity
Humidity
Airflow
Sound