Principles of Anesthesia

ST210Concorde Career College

Objectives

• Assess the action, uses, and modes of administration of drugs and anesthetic agents used in the care of the surgical patient

• Recognize general terminology and abbreviations associated with anesthesia

• Recognize the side effects and contraindications for the use of various anesthetic drugs

Objectives

• Interpret factors that influence anesthesia selection for individual patients

• List the equipment used during anesthesia administration

• Analyze how sterile technique is used in relation to anesthesia procedures

• Compare and contrast the roles of the surgical technologist and circulator during the administration of anesthesia

Definitions

Anesthesia - From the Greek meaning lack of sensation; particularly during surgical intervention.

Definitions

• Review• HYPNOSIS• ANESTHESIA• AMNESIA• MUSCLE RELAXATION• POSITIONING• HOMEOSTASIS

Anesthesia History Timeline

• 1500s: Coca leaves used as local anesthetic during trephination of the skull

• 1725: Ether was discovered by Spanish chemist Raymundus Lillius

• 1800s: Social use of ether - “ether frolics”

• 1842: Crawford W. Long may have been the first to use ether for surgical pain control, but did not publish his findings until 1848

Anesthesia History Timeline

• 1846: William T.G. Morton performed surgery at Mass General Hospital in front of an audience– First Surgical Use of Anesthetics – Click Here– Ether Dome: Mass General Hospital

• 1905: Long Island Society Anesthetists (LISA) formed• 1936: LISA changed name to ASA (American Society

of Anesthesiologists)

Anesthesia History Timeline

Anesthesia History Timeline

Anesthesia History Timeline

Anesthesia Administration

Two primary methods of anesthesia administration:

1.Inhalation Agents– Typically for General Anesthesia

2.Injectable Agents– Typically for Nerve Conduction Blockade, or– Regional Anesthesia

General Anesthesia

Alteration in the patient’s level of consciousness (patient is “asleep”)

Accomplished by:• Agent inhalation• Agent injection• Agent instillation

Nerve Conduction Blockade

Prevent initiation of conduction of nerve impulses along a nerve pathway

(patient is “awake”)

Anesthesia Selection

Factors that affect selection of the type of anesthesia:

• Planned procedure and estimated duration• Patient position• Age, size, and weight of the patient• Patient status (emotional, mental, and physical) • General health of the patient (comorbid conditions)

Anesthesia Selection

Factors that affect selection of the type of anesthesia: (continued)

• Medication status• Allergy status• History of substance abuse• Emergency conditions• Preference (surgeon, anesthesia provider, patient)

ASA Risk Classification System

• Class 1 – No organic, physiological, biochemical, or psychiatric disturbance

• Class 2 – Mild to moderate systemic disease or disturbance (e.g., controlled hypertension or diabetes, asthma, anemia, smoking, mild obesity, age – less than 1 or greater than 70)

ASA Risk Classification System

• Class 3 – Severe systemic disease or disturbance (e.g., stable angina, previous MI, poorly controlled hypertension or diabetes, symptomatic respiratory disease, massive obesity)

• Class 4 – Severe (life threatening) systemic disease or disturbance (e.g., unstable angina, CHF, debilitating respiratory disease, hepatorenal failure)

ASA Risk Classification System

Class 5 – Moribund

Class 6 – Brain dead

E – Emergency modifier

Roles of the Surgical Team Members

(refer to the tables on pp. 257-261)

• Preoperative case management duties

• Intraoperative case management duties • Postoperative case management duties

Anesthesia Evaluation & Preparation

Preanesthetic evaluation and preparation processes

• Preoperative routine• Preoperative education• Patient possessions• Preoperative procedures

Preoperative Routine

– Enema– Nail polish and makeup– Hygiene (shower and shave)– Attire– Sedation– Call to the OR– Family visit– Identification, chart, consent, transportation,

transfer...

Anesthesia EquipmentEquipment and techniques used to monitor the patient

• Blood pressure• O2 Sat

• Temperature• I&O• Heart• BIS

• Respiration– SARA

• Doppler• Peripheral Nerve

Stimulator• ABG

Anesthesia Equipment Equipment and techniques used to monitor the patient

Blood Pressure

Sphygmomanometer(with stethoscope)

Anesthesia Equipment Equipment and techniques used to monitor the patient

O2 Sat

Pulse Oximeter

Anesthesia Equipment Equipment and techniques used to monitor the patient

Temperature

ThermometerEsophageal Stethoscope

with temperature probe

Anesthesia Equipment Equipment and techniques used to monitor the patient

I&O

Intake and Output

Anesthesia Equipment Equipment and techniques used to monitor the patient

Heart

Apical Stethoscope Earpiece

Anesthesia Equipment Equipment and techniques used to monitor the patient

Heart

ElectrocardiogramElectrodes

Anesthesia Equipment Equipment and techniques used to monitor the patient

Heart

ElectrocardiogramLeads

Anesthesia Equipment Equipment and techniques used to monitor the patient

Heart

Electrocardiogram(ECG)

Anesthesia Equipment Equipment and techniques used to monitor the patient

BIS Monitor(Bispectral Index)

Anesthesia Equipment Equipment and techniques used to monitor the patient

Respiration

SARA(System for Anesthetic

and Respiratory Analysis)

Anesthesia Equipment

SARA is capable of several functions including:

• Capnography

• Spirometry

• Oxygen analysis

Anesthesia Equipment Equipment and techniques used to monitor the patient

Doppler

Anesthesia Equipment Equipment and techniques used to monitor the patient

Peripheral Nerve Stimulator

Anesthesia Equipment Equipment and techniques used to monitor the patient

ABG(Arterial Blood Gas)

Methods of Anesthetic Administration

• General– Balanced– Neuroleptanalgesia

• Nerve Conduction Blockade– Regional– Local– Topical

Common Anesthetic Agents

• Inhalation Agents– Oxygen– Nitrous oxide– Waste gases

Common Anesthetic Agents

Oxygen

• Inhalation agent• Not anesthetic agent• Necessary for life

Common Anesthetic Agents

Nitrous Oxide

• Produces analgesia and amnesia

• Produces little muscle relaxation

• Decreases myocardial contractility and respiratory function

Common Anesthetic Agents

Waste gas scavenger system

Common Anesthetic Agents

Volatile Agents

• Liquids with potent evaporative vapors• CNS depression produces general anesthesia• Myocardial and respiratory depression• Decrease muscle tone

Volatile Agents

• Halothane (Fluothane)• Enflurane (Ethrane)• Isoflurane (Forane)• Desflurane (Suprane)• Sevoflurane (Ultane)

Halothane

• Rapid acting• Sweet odor• Nonirritating to the

respiratory tree• Used for induction

and maintenance

Enflurane

• Halogenated• Sweet odor• Rapid induction• Rapid recovery• Hypotension (when not

surgically stimulated)• Potentiates

nondepolarizing NMB

Isoflurane

• Rapid induction and recovery

• Musty smelling• Profound respiratory

depression and hypotension

• Markedly potentiates NMB

• Increases ICP

Desflurane

• Halogenated• Requires heated

vaporizer• Pungent aroma• Not biotransformed in

the liver

Sevoflurane

• Odorless• No irritation to

respiratory tree• Causes bradycardia, hypotension,

dysrhythmias, decreases cardiac output

Intravenous Agents

• Permit rapid pleasant transition from consciousness to unconsciousness

• Produce marked sedation and amnesia• Produce hypotension and respiratory depression• Some induction agents may also be used for

maintenance

Intravenous Agents for Induction

• Propofol (Diprivan)• Etomidate (Amidate)• Thiopental sodium (Pentothal Sodium)• Methohexital sodium (Brevital)

Propofol

• Sedative hypnotic• Soy oil in water emulsion

(inhibits microbial growth)• Induction or conscious

sedation• Alkaline – irritating to the

vein• Causes increased ICP and

hypotension

Propofol• Formulations of intravenous anesthetic propofol emulsions

are provided which contain sufficiently low concentrations of soybean oil to produce a stable emulsion and simultaneously provide reduced nutrients, which inhibit microbial growth thereby providing protection against accidental microbial contamination during long-term IV infusions. In addition to the inhibition of microbial growth due to a reduction of nutrients, the formulation exhibits unanticipated additional microbial inhibition due to an increased availability of propofol. The low concentration of soybean oil also provides a formulation that reduces the chances of fat overload when administered over an extended period of time to chronically ill patients.

Etomidate

• Non-barbiturate hypnotic

• Produces minimal cardiovascular system effects

• Causes nausea, vomiting, and adrenal suppression

Thiopental Sodium

• Potent barbiturate• Short acting• Alkaline – irritating to

the vein• Less expensive than

propofol

Methohexital Sodium

• Similar in action to propofol and thiopental sodium

• Ultrashort onset and duration of action

• Ideal agent for short term loss of consciousness during nerve conduction blockade

Dissociative Agents

• Interrupt the associative pathways of the brain (patient appears awake, but is unaware of surroundings

• Produce amnesia and profound analgesia

Dissociative Agents

Ketamine Hydrochloride (Ketalar)

• Most commonly used• IM or IV administration• Rapid induction of dissociative state• Potentiated by other agents (narcotics/barbiturates)• Increases muscle tone• Increases ICP and IOP

Opiate/Opioids

• Narcotic (Class II) analgesics(decrease pain impulse transmission from CNS and spinal cord receptors)

• Also produce sedation • Produce euphoria and decrease anxiety• High doses lead to unconsciousness and respiratory

depression

Opiate/Opioids

• Morphine sulfate• Meperidine (Demerol)• Fentanyl citrate (Sublimaze)• Sufentanil citrate (Sufenta)• Alfentanil hydrochloride (Alfenta)• Remifentanil hydrochloride (Ultiva)

Narcotic Antagonists

• Antagonize or reverse narcotic effects• Increased level of consciousness seen in 1-2

minutes• Naloxone hydrochloride (Narcan)

Benzodiazepines

• Sedative tranquilizers• Reduce anxiety/apprehension• Adjunct to general anesthesia (reduce amount

and concentration of other agents)• Do not produce analgesia

Benzodiazepines

• Diazepam (Valium)• Midazolam (Versed)• Droperidol (Inapsine)

Benzodiazepine Antagonist

• Flumazenil (Mazicon)– Reverses the sedative effects, but may not reverse

the amnesia effects– May cause convulsions– Rebound sedation and respiratory depression may

occur

Neuromuscular Junction

Neuromuscular Junction Review

• http://www.wisc-online.com/objects/ViewObject.aspx?ID=AP2804

Neuromuscular Junction

Neuromuscular Blockers (NMBs)

• Skeletal muscle relaxants (cause weakness – paralysis)

• Interfere with passage of impulses from motor nerves to skeletal muscles

• May use only one dose or re-administer throughout procedure

Neuromuscular Blockers (NMBs)

• Used to relax the jaw for ease of endotracheal intubation

• Muscles of respiration are affected (mechanical ventilation required)

• Surgical site relaxation to allow for tissue retraction

Neuromuscular Blockers (NMBs)

Depolarizing Agents

• Mimic release of acetylcholine across the neuromuscular junction

• Causes muscle contraction (fasciculation) followed by a period of muscle fatigue

• Patient may experience postprocedure muscle ache

Neuromuscular Blockers (NMBs)

Depolarizing Agents

• Metabolized by plasma cholinesterase in the synapse reversing the effect of the agent

• NO pharmacologic antagonist

Neuromuscular Blockers (NMBs)

Depolarizing Agents

• Succinylcholine (Anectine)– Most commonly used– Short acting– Known triggering agent for MH

• Decamethonium (Syncurine)

Neuromuscular Blockers (NMBs)

Nondepolarizing Agents

• Compete for post synaptic receptors• Prevents stimulation of muscle contraction• Duration (short, intermediate, long)• Spontaneous recovery may occur• Pharmacologic antagonist available

– Edrophonium chloride (Tensilon)– Neostigmine (Prostigmin)

Neuromuscular Blockers (NMBs)

Nondepolarizing Agents

Short Acting

• Mivacurium chloride (Mivacron)• Vecuronium bromide (Norcuron)• Rocuronium bromide (Zemuron)

Neuromuscular Blockers (NMBs)

Nondepolarizing Agents

Intermediate Acting

• Atracurium Besylate (Tracrium)• Cisatracurium besylate (Nimbex)

Neuromuscular Blockers (NMBs)

Nondepolarizing Agents

Long Acting

• Tubocurarine chloride (Curare)• Pancuronium bromide (Pavulon)• Metocurine iodide (Metubine)

Antimuscarinic (Anticholinergic)

• Used to limit salivation and bradycardia

• Two commonly used agents– Atropine sulfate– Glycopyrrolate (Robinul)

NSAIDs

Nonsteroidal Anti-Inflammatory Agents

• Aid in pain management

• Main agent– Ketoralac (Toradol) – May be given IM

intraoperatively to aid in emergence and recovery pain management

Gastric Acid Management

• Used to alter the pH of gastric secretions and reduce gastric acid volume

• Reduce the risk of stress ulcer• Agents

– Oral agent citric acid (Bicitra)– IV agent cimetidine (Tagamet)– IV agent ranitidine (Zantac)– Metoclopramide (Reglan) – promotes pyloric emptying

Antiemetic

• Used to prevent or alleviate nausea• Agents

– Droperidol (Inapsine)– Metoclopramide (Reglan)

Administration Devices

• Anesthesia Machine• Vaporizer• Anesthesia Circuit • Airway Delivery/Maintenance Devices• Hypo/Hyperthermia Devices

Administration Devices

Anesthesia Machine

Administration Devices

Anesthesia Cart

Administration Devices

Vaporizer

Administration Devices

Vaporizer

Administration Devices

Anesthesia Circuit

Administration Devices

Administration Devices

Soda lime (calcium hydroxide)

• Chemically removes carbon dioxide from the breathing circuit with the aid of activators such as sodium, potassium, and barium hydroxide

Administration Devices

Airway Delivery/Maintenance

Devices

Face Mask

Administration Devices

Airway Delivery/Maintenance

Devices

Oxygen Mask

Administration Devices

Airway Delivery/Maintenance

Devices

Nasal Cannula

Administration Devices

Airway Delivery/Maintenance

Devices

Endotracheal Tube

Administration Devices

Airway Delivery/Maintenance

Devices

Laryngoscope

Administration Devices

Positioning of Laryngoscope

Administration Devices

Cuffed ET Tube in Position

Administration Devices

Airway Delivery/Maintenance

Devices

McGill Forceps

Administration Devices

Airway Delivery/Maintenance

Devices

Oral Airway

Administration Devices

Airway Delivery/Maintenance

Devices

Nasal Airway (Trumpet)

Administration Devices

Airway Delivery/Maintenance

Devices

Nasal Airway (Trumpet)

Administration Devices

Airway Delivery/Maintenance

Devices

Tracheotomy Tube

Administration Devices

Airway Delivery/Maintenance

Devices

Tracheotomy Tube

Administration Devices

Airway Delivery/Maintenance

Devices

Laryngeal Mask Airway(LMA)

Administration Devices

Airway Delivery/Maintenance

Devices

Laryngeal Mask Airway(LMA)

Administration Devices

Ambu Bag

Administration Devices

Laryngeal Tracheal Anesthesia (LTA) Kit

Hyper/Hypothermia Devices

• Bair Hugger• Heating/Cooling Unit• Heat Lamp

Hypo/Hyperthermia Devices

Bair Hugger

Hyper/Hypothermia Devices

Heating/Cooling Unit(Blanket)

Hyper/Hypothermia Devices

Heat Lamp

Positioning for Anesthesia

• Supine

• Lateral

• Sitting

General Anesthesia

• Alteration in the patient’s level of consciousness

• Accomplished by agent inhalation, injection, or instillation

General Anesthesia

Goals of General Anesthesia

• Lack of sensation• Lack of movement• Muscle relaxation• Autonomic control (homeostasis)

General Anesthesia

(Four Stages – Depth)

• Stage I – Amnesia

• Stage II – Excitement

• Stage III – Surgical Intervention (4 planes)

• Stage IV – Overdose

General Anesthesia

(Four Phases)

• Induction

• Maintenance

• Emergence

• Recovery

General Anesthesia

Advantages Disadvantages

Cricoid Pressure (Sellick’s Maneuver)

Purpose – To minimize the risk of aspiration

• Apply external pressure to the cricoid cartilage using the thumb and first finger to form a “V”

• Pressure occludes the esophagus between the cricoid ring and the body of the 6th vertebral body

• Must apply prior to induction and maintain until patient is intubated

• Do NOT release pressure without permission from the anesthesia provider

Cricoid Pressure (Sellick’s Maneuver)

Indications

• Emergency surgery shortly after eating

• NPO status cannot be verified

• GI bleeding

• Basic life support, if needed

Nerve Conduction Blockade

• Anesthetic agent is used to prevent initiation and/or transmission of impulses along an individual nerve pathway or at a nerve plexus to provide anesthesia to tissues adjacent or distal to the site.

Nerve Conduction Blockade

• Two types of agents used to accomplish nerve conduction blockade– Amino amide group

• Metabolized in the liver• Excreted by the kidneys

– Amino ester group• Biotransformed by pseudocholinesterase in the plasma

Nerve Conduction Blockade

• Amino amide group– Lidocaine hydrochloride (Xylocaine, Lignocaine)– Mepivacaine hydrochloride (Carbocaine)– Bupivacaine hydrochloride (Marcaine,

Sensorcaine)– Etidocaine hydrochloride (Duranest)

Lidocaine Hydrochloride

• Rapid onset• Moderate duration• Topical, local, regional• Available with or

without epinephrine• Has properties that

affect the heart

Mepivacaine Hydrochloride

• Action similar to lidocaine

• Longer action than lidocaine

• Does not produce significant cardiac effects

Bupivacaine Hydrochloride

• Four times as potent as lidocaine

• Longer onset of action than lidocaine

• Longer duration of effect than lidocaine

• Available with or without epinephrine

Etidocaine Hydrochloride

• Prolonged onset• Long duration• Highly toxic• Contraindicated in

children

Nerve Conduction Blockade

• Amino ester group– Cocaine hydrochloride– Procaine hydrochloride (Novocain)– Tetracaine hydrochloride (Cetacaine, Pontocaine)

Cocaine Hydrochloride

• CNS stimulant• Controlled substance• Topical application

only• Produces anesthesia

and vasoconstriction causing shrinkage of mucous membranes

Procaine Hydrochloride

• Similar properties to cocaine

• Less toxic than cocaine

• SC, IM, or intrathecal

Tetracaine Hydrochloride

• Slow onset• Prolonged duration• Primarily used as a

topical agent

Nerve Conduction Blockade

Adjunctive Agents

• Influence onset and duration of action• Two common agents

– Hyaluronidase (Wydase)– Epinephrine (Adrenalin)

MAC

(Monitored Anesthesia Care)

• Provides monitoring, sedation, analgesia, and amnesia

• Used in conjunction with nerve conduction blockade

Nerve Conduction Blockade

Types of Nerve Conduction Blockade

• Topical

• Local

• Regional

Topical Anesthesia

• Placement of a nerve conduction blocking agent onto a tissue layer (skin or mucous membrane)

• Anesthesia is limited to the area in contact with the anesthetic agent

• In addition to pharmaceutical agents, cryoanesthesia is another example of topical anesthesia

Local Anesthesia

• Placement of a nerve conduction blocking agent onto a tissue layer

• Only the nerve or nerves that supply that limited (localized) area are affected

Regional Anesthesia

• Nerve conduction blocking agent is injected along a major nerve pathway blocking conduction of impulses from all tissue (the entire region) distal to the injection site

• Examples of regional anesthesia include:– Bier Block– Nerve Plexus Block– Spinal– Epidural– Caudal

Bier Block

• Provides anesthesia to the distal portion of an extremity• Used on procedures expected to last one hour or less• Procedure is as follows:

– IV catheter is inserted– Double cuffed tourniquet is applied– Exsanguination is achieved with the use of an Esmarch bandage– Proximal cuff of tourniquet is inflated– Nerve conduction blocking agent is injected intravenously distal to the

tourniquet– Distal cuff of tourniquet may be inflated and then the proximal cuff

may be deflated

Nerve Plexus Block

• Anesthetic solution is injected at a major nerve plexus – usually located at the base of a structure. For example the brachial plexus is at the base of the arm.

Spinal (Intrathecal) Block

• Anesthetic solution is injected into the subarachnoid space (into the CSF)

• Provides loss of sensation below the diaphragm (patient should be able to breathe independently)

Epidural Block

• Anesthetic solution is injected in the epidural (outside the dura) space and is absorbed into the CSF through the dura

• Provides loss of sensation below the diaphragm (patient should be able to breathe independently)

Caudal Block

• Type of epidural that is administered with the patient in the lithotomy position.

• Agent is injected into the epidural space of the sacral canal

• Used primarily in obstetrics

Nerve Conduction Blockade

Advantages

• Patient is awake• May be used to avoid

undesirable cardiac and respiratory side effects

• Recovery time from anesthesia is decreased

Disadvantages

• Patient is awake• Patient maintains

sensory awareness• Patient retains ability to

move• Positioning may be

difficult to maintain

Postanesthesia Care (Recovery)

• May occur in the PACU or the ICU• Duration approximately 1 hour or longer, if

necessary – Patient is transferred or discharged when ready

• Patient is monitored• Ventilatory support is provided, as needed• Medications (e.g., analgesic, antibiotic) and fluids

(e.g., blood) are provided as needed• Dressings are maintained• Emotional support provided, as needed

Adjunctive Anesthesia Treatments

• Induced Hypothermia• Induced Hypotension• Neuroleptanalgesia• Neuroleptanesthesia

Alternative (Nontraditional) Anesthesia Treatments

• Hypnoanesthesia

• Acupuncture