ANESTHESIA EQUIPMENTS

EE517 Therapeutic and Prosthetic Devices in Biomedical Engineering

TERM PROJECT PRESENTATION

Duygu DEMİRKOL

24.12.2012

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Outline1. Introduction

1.1. What is Anesthesia?1.2. Why do We Need Anesthesia?

2. History of Anesthesia3. Who is Anesthetist?

3.1. Applied Drugs by the Anesthetist4. Types of Anesthesia

4.1. Local Anesthesia4.2. Regional Anesthesia4.3. General Anesthesia

5. Modern Anesthesia Machines5.1. General Look at Modern Anesthesia Machines5.2. Patient Breathing Circuit with Anesthesia Machine5.3. Parts of the Anesthesia Machine

5.3.1. Flow Meters5.3.2. Vaporizers5.3.3. Ventilators5.3.4. CO2 Absorbers5.3.5. Monitoring Devices5.3.6. Pipeline Inlets and Cylinders5.3.7. Pressure Regulators

6. Summary7. References

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1. INTRODUCTION1.1. What is Anesthesia?

The word "anesthesia" coined by Oliver Wendell Holmes in 1846.Anesthesia is a word derived from the Greek:

An = Absence Esthesia = SenseAnesthesia = Absence of Sence

• Anestesia is the state of insensibility.

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Anesthesia is a way to control pain during a surgery or procedure by usingmedicine called anesthetics.It can help control your

Breathing,Blood pressure,Blood flow,Heart rate and rhythm.

Anesthesia causes brain to hibernate.

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2.1. Why Do We Need Anesthesia?Painful operationsThe shock alone could easily be enough to cause death.Trauma of surgery made it difficult for surgeons to perform their tasks.Surgeries are long prosedures.Without anesthesia surgeons would have to be quick during operation whichwould led to serious or fatal human errors.

Anesthesia may be help to:Relax you.Block pain.Make you sleepy or forgetful.Make you unconscious for your surgery.

2. HISTORY of ANESTHESIAAlcohol is the oldest known sedative; it was used in ancient Mesopotamiathousands of years ago.

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Opium was used for anesthesia asearly 3400 BC.Opium is named “afyon çiçeği” inTurkish.

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The first public demonstration of general anesthesia by William T. G. Mortonin1846 in the Ether Dome at Massachusetts General Hospital, Boston.

Anesthetist is the operator who is responsible from anesthesia machine andadminister anesthetic agent to the patient.Anesthetist observes the patient during the surgery by using somemonitoring devices.

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2. WHO IS ANESTHETIST?

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ECG is used to be sure that heart is beating properly and functioning as a

pump and pumped blood is reaching to the tissues in adequate quantities.

Anesthetist is expected to be sure that the patient breaths and the

oxygenation of blood is enough with utilizing pulse oximetry devices.

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After the anesthetic agent is applied to the patient, anesthetist examines

position of eye globe, palpebral reflex, corneal reflex, jaw muscles and

decides to the depth of anesthesia.

Anesthetist arrange the amount of anesthetic gas which is applied to the

patient.

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Anesthetist is a qualified doctor specializing in the administration ofanesthetics.Technological machines help the anesthetists, however they are still needed orexpected to be vigilant.

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There is a need toanesthetists sinceancient days.

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Although modern anesthesia machines use high technology and they are developed, The best device is only as good as the anesthetist behind it.

3.1. Applied Drugs by the Anesthetist

Anestehetics

Prevent patient from painHas various types that can be applied by generally or regionally.

Hypnotics

Applied before the general anestesia to make patients sleep. Efficieny time is about 8-10 minutes.

Amnesics

Hypnotics with lower dose. Reduce the stress of patient.Make forgetfulness. Suggest for kids generally to prevent the future anxiety.Reveals the subconscious opinions of patients. Used to make the person telling the truth.

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Neuromuscular Blockers

Applied before the general anestesia to make patients relax. (muscle relaxant)Anesthetic Gases

Used in vaporizers in the anestesia machinesGiven to the patient under general anestesia through respirationUsed in long surgery operations for maintaining anestesia.

3.1. Applied Drugs by the Anesthetist(continue)

Monitoring Drug Effects :

During surgery, the monitoring of the depth of general anesthesia is inevitablefor a successful operation.Anesthetic depth is perceived qualitatively by anesthetists. By checking

pupils on eyes,

effect of respiration and

musculature.Nondepolarizing muscle relaxants are monitored by electrical nervestimulation. Applying 50-100Hz tetanic stimulation or train of four (TOR)stimuli at 2 Hz (measuring the first and last stimulus response) are two mainmethod used clinically in order to achieve more realistic data.EEG signals and quantitative measures of action potentials are anothermethods to observe the depth of general anesthesia. However these are notclinically used. By signal processing techniques quantitative data must be ableto be obtained.

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Anesthesia Depth Concept & Anesthetic Levels:

Partial pressure of anesthetic in the brain determines the depth of anesthesia.Depth of anesthesia must be balanced during entire operation. If not so;

Anesthesia awareness,

Failure of vital functions of the body and

Side effects of anesthesia are inevitable. Anesthesia awareness, occurs during general anesthesia, on the operating table, when the patient has not been given enough of the general anesthetic or analgesic. The patient may get conscious during operation (often when agents used to paralyze the patient have been administered).Anesthesia awereness is mostly occurs in cardiac operations. Due to the misadjusment of analgesic or hypnotic anesthetic agents.

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Video-1: Anesthesia Depth Concept

Aspect Medical Systems Provides Anesthesia Awareness Patient

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4.1. Local Anesthesia

Anesthetic drug is usually injected into the tissue to numb just the specificlocation of your body requiring minor surgery.

4. TYPES OF ANESTESIA

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4.2. Regional Anesthesia

Anesthesiologist makes an injection near a cluster of nerves to numb thearea of your body that requires surgery.You may remain awake, or you may be given a sedative, either way you donot see or feel the actual surgery taking place.There are several kinds of regional anesthesia; the there most common are:

Spinal AanesthesiaEpidural AnesthesiaIntravenous Regional Anesthesia

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Spinal AnesthesiaLower portion of the body is anesthetized.Thin needle goes into lumbar vertebrae (contains Cerebrospinal fluid)All nerves that are located at specific part are anesthetizedCSF Leakage causes headache generally

Epidural AnesthesiaIn Epidural anesthesia the passage of a needle to the space just outsideof the spinal canal. A large volume of anesthetic is injected. (e.g. 20 ml)

Intravenous Regional Anesthesia :A large volume of anesthetic is injected. However arm is tourniqueted (cutting the blood flow).Blood flow is prevented by a tight elastic wrapping. This prevents the anesthetic loss into unwanted region.

4.2. Regional Anesthesia

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Video-2: Epidural & Spinal Anesthesia

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4.3. General AnesthesiaUnder general anesthesia patient is

unconscioushave no awareness or other sensations.

There are a number of general anesthetic drugs - some are gases or vaporsinhaled through a breathing mask or tube and others are medicationsintroduced through a vein.During anesthesia, you are carefully monitored, controlled and treated byyour anesthesiologist.A breathing tube may be inserted through your mouth and frequently intothe windpipe to maintain proper breathing during this period. (entubation)At the conclusion of surgery, your anesthesiologist will reverse the processand you will regain awareness in the recovery room.

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Video-3: Intubation and Mechanical Ventilation

5. MODERN ANESTHESIA MACHINES

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5.1. General Look at Modern Anesthesia Machines

System carries four differentinternal subsystems:

Gas delivery systemPatient breating systemWaste gas scavengingsystemVentilator

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5.1. General Look at Modern Anesthesia Machines

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5.1. General Look at Modern Anesthesia Machines

5.2. Patient Breathing Circuit with Anesthesia Machine

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Anestesia delivery system is half closed loop system

Breathing Circuits :Anesthesia machine continously supply fresh air and anesthetic gasmixture. Patient may benefit from rebreathing the expired gases. This conserves thebody heat and moisture.However this rebreathing lead to accumulation of CO2. Therefore removalof CO2 is necessary.In anesthesia machine the apparatus satisfying all of these is called as thebreathing circuit.

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5.3. Parts of the Anesthesia Machine

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Video-4: Anesthesia Machine Video Part 1

5.3.1. Flow MetersA flow meter is an instrument used to measure linear, nonlinear, mass or volumetric flow rate of a gas. Firstly, O2 or N2O or air flow is arranged with flow meters and flow control.In order to make an accurate measurement, flow meter should be designed or calibrated for a specific gas.Today, we have two types of flow meters: Mechanical and Electronic Flow Meters.

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Electronic Flow Meters Mechanical Flow Meters

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Another important point in choosing a flow meter for a process is that you require rate measurement and/or totalization from the flow meter.

N2O (Nitrogen Oxide – Laugh Gas)

Usage is reduced, lately. Becaouse of the possible risks:AnemiaOxygen deprivationLoss of motor controlVitamin B12 interferenceFolic acid interferenceNausea, Gut, Ear Pain

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5.3.2. Vaporizes

Vaporises are utilized to evaporate the liquid anestetics to gas form. Than these gas form is mixed with the air flowFlowmeters are connected to vaporizers.

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Sevoflurane Desflurane

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The steps of vaporization:First oxygen and anesthetic gasmixture flows into the chambercontaining anesthetic agent. Here gas completely saturated byanesthetic vapor.Then this mixture rejoins themain stream eventually goes intobreathing circuit.Concentration control valve is for the fraction of gases entering into the chamber.

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Temperature sensing bellows evaporates the liquid anestetics to gas form.Specific for one anesthetic, because the vapor pressures of liquid anesthetics are different.Temperature compensating bypass valve is further adjusting the mixing ratio, so the variations due to the temperature is overcome.

5.3.3. Ventilators

Manual ventilation with using baloons is advantageous if non continues ventilation exists. However, when the patient is paralyzed, automatic ventilator is required.Anesthesia ventilators include isolating bellows, which can be replaced with manual breathing bag.Compression and expansion causes the anesthetic gas flows into and out to the breathing circuit.Ventilator controls :

Tidal Volume (The volume of a single breath).Ventilation rate used to arrange the required air to the patient to inspirate for every breath.

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Mechanic ventilation can be called to this devices.MV can be modes of volume or pressure control.

For volume control ml/breathFor pressure control mbar/breath

Patients’ required volume is 6-8 ml/kg.Volume control is widely used in laparoscopic operations. Pressure control is widely used in chronicpulmonary diseases and pediatrics surgery.

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Bellows Assembly

5.3.4. CO2 Absorber

Used to absorb the return CO2from the patient.(expiration – breath out)

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Types of CO2 Absorber

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Soda lime

The most used CO2 absorberIncludes: %94 Cad(OH)2, %5 NaOH and %1 KOH Mostly, ethyl violet is used as an indicator. Normally yellow color, but turns to violet with increasing CO2.

Baralyme

%80 Ca(OH)2, %20 Baç(OH)2Normally pink color, but turns to violet with increasing CO2.

5.3.5. Monitoring Devices

Monitoring of the measurements isa must in anesthesia man-machinesystemThe system is generally capable of

ECG monitoringBlood pressure measurements(direct or indirect)Supplementary pressure, flowinformationCardiac output with the aid ofmultichannel pressure monitors.

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5.3.5. Monitoring Devices

Pulmonary function is obtained visually by the anesthetist.Stethescope is also a general-purpose monitoring device to get the heart andlung sounds.This system also includes nerve stimulator for neromuscular junctionmonitoring. (TOF)Temperature should also be monitored during the operation, because malignanthypertermia must be avoided. Therefore system includes progressive cooling.

Only one drug “DANTROLEN” is used for malign hypertermia.This drug is not produce in Turkey, and also not imported because it is too cheap.

In addition an alarm system generally exist, which let the anesthetist knowequipment system failures.

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Video-5: Anesthetic Monitoring Video

5.3.6. Pipeline Inlets and Cylinders

Pipeline inlets are the inputs for the systemic O2, N2O and Air. Because of the side effects, there is not any N2O gas in mostly Europian country hospitals.

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PISS - Pin-Index Safety System : prevent accidental mounting of a gas cylinder into incorrect yoke.DISS – Diameter Index Safety : pipeline inverts are connected to non-interchangeable connectors.

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Anesthetic Agent Cylinders

Anesthetic agent cylindersserve as emergency and temporary supply.

The primary, gas supply of the anesthesia machine is the central storage facility, with plumbing going directly to operating rooms.

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These cylinders are color coded cylinders. So that man caused errors are minimized.

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5.3.7. Pressure Regulators

The pressure at both anesthetic agent cylinders and hospital’s main supply are to high to be applied to a patient.Therefore, it is required to reduce these pressures to a suitable value.In order to achieve this goal, mechanical pressure reducers or regulators are used at gas entrances of anesthesia machines.Approximate pressure value which is used in anesthetic machine design is 45 Psi (310 KPa).

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6. SUMMARYAnesthesia is a solution technique for painful , long procedures satisfying patients insensibility.There are 3 different types of anesthesia

Local : Part of body is anesthetized (not include nerves, e.g. surface of skin).Regional : Part of body with nerves is anesthetized .General : Entire body is anesthetized.

Body reacts differently for different anesthetic agents.Anesthesia Depth is important to prevent cardiac problems, anesthesia awareness and fatal errors during surgery.

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Anesthesia Subsystems

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Breathing Circuit

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6. REFERENCES

Anesthesia Delivery Aparatus, Newbower, Cooper, Philip.www.seifmedgraphics.comhttp://anesteziseminerleri.com/maht.htmlhttp://www.justsayn2o.com/nitrous.dangers.htmlhttp://en.wikipedia.org/wiki/History_of_general_anesthesia

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