AnesthesiaAnesthesia

Dr Abdollahi

AnesthesiaAnesthesia

From Greek anaisthesis means ”not sensation” Listed in Bailey´s English Dictionary 1721. When the effect of ether was discovered”anesthesia”

used as a name for the new phenomenon.

Basic Principles of AnesthesiaBasic Principles of Anesthesia

Anesthesia defined as the abolition of sensation Analgesia defined as the abolition of pain ““Triad of General AnesthesiaTriad of General Anesthesia””

need for unconsciousness need for analgesia need for muscle relaxation

History of AnesthesiaHistory of Anesthesia

History of AnesthesiaHistory of Anesthesia

Ether synthesized in 1540 by Cordus Ether used as anesthetic in 1842 by Dr.

Crawford W. Long Ether publicized as anesthetic in 1846 by

Dr. William Morton Chloroform used as anesthetic in 1853 by

Dr. John Snow

History of AnesthesiaHistory of Anesthesia

Endotracheal tube discovered in 1878 Local anesthesia with cocaine in 1885 Thiopental first used in 1934 Curare first used in 1942 - opened the “Age

of Anesthesia”

Anesthesiologists care for the surgical patient in the preoperative, intraoperative, and postoperative period . Important patient care decisions reflect the preoperative evaluation, creating the anesthesia plan, preparing the operating room, and managing the intraoperative anesthetic.

Preoperative EvaluationPreoperative Evaluation

The goals of preoperative evaluation include assessing the risk of coexisting diseases, modifying risks, addressing patients' concerns, and discussing options for anesthesia care.

What is the indication for the proposed surgery? It is elective or an emergency?

The indication for surgery may have particular anesthetic implications. For example, a patient requiring esophageal fundoplication will likely have severe gastroesophageal reflux disease, which may require modification of the anesthesia plan (e.g., preoperative non particulate antacid, intraoperative rapid sequence induction of anesthesia).

What are the inherent risk of this surgery?

Surgical procedures have different inherent risks. For example, a patient undergoing coronary artery bypass graft has a significant risk of problems such as death, stroke, or myocardial infarction.

A patient undergoing cataract extraction has a low risk of major organ damage.

Does the patient have coexisting medical problems? Does the surgery or anesthesia care plan need to be modified because of them?

Has the patient had anesthesia before? Were there

Complication such as difficult airway management? Does the patient have risk factor for difficult airway management?

Creating the Anesthesia PlanCreating the Anesthesia Plan

After the preoperative evaluation, the anesthesia plan can

be completed. The plan should list drug choices and doses

in detail, as well as anticipated problems .Many variations on a given plan may be acceptable, but the trainee and the supervising anesthesiologist should agree in advance on the details.

Preparing the Operating RoomPreparing the Operating Room

After determining the anesthesia plan, the trainee must prepare the operating room .

Anesthesia ProvidersAnesthesia Providers

Anesthesiologist ( aphysician with 4 or more yearsof speciality training in anesthesiology after medical school)

Certified registered nurse anesthetist (CRNA), working under the direction and supervision of an anesthesiologist or a physician

CRNA must have 2 years of training in anesthesia

Patient SafetyPatient Safety

Patient risk and safety are concerns during surgery and anesthesia .

Data from a number of studies of death caused by anesthesia indicate a death rate ranging from 1 per 20,000-35,000.

A fourfoulded decline over the last 30 years even though surgical procedures are undertaken on increasingly sicker and much higher risk patients than in the past.

Awareness of potential problems and constant vigilance (the process of paying close and continuous attention) are crucial to good patient care.

Preoperative preparation patient Preoperative preparation patient evaluationevaluation

Anaesthesiologist: reviews the patient´s chart,

evaluate the laboratory data and diagnostic studies such as electrocardiogram and chest x-ray,

verify the surgical procedure, examins the patient, discuss the options for anesthesia and the attendant risks

and ordered premedication if appropriate

The physical status classification The physical status classification

Developed by the American Society of Anesthesiologist (ASA) to provide uniform guidelines for anesthesiologists.

It is an evaluation of anesthetic morbidity and mortality related to the extent of systemic diseases, physiological dysfunction, and anatomic abnormalities.

Intraoperative difficulties occur more frequently with patients who have a poor physical status classification.

Choice of anesthesiaChoice of anesthesia

The patient´s understanding and wishes regarding the type of anesthesia that could be used

The type and duration of the surgical procedure The patients´s physiologic status and stability The presence and severity of coexisting disease The patient´s mental and psychologic status The postoperative recovery from various kinds of anesthesia Options for management of postoperative pain Any particular requiremets of the surgeon There is major and minor surgery but only major anesthesia

Types of anesthesia careTypes of anesthesia careGeneral AnesthesiaGeneral Anesthesia

Reversible, unconscious state is characterised by amnesia (sleep, hypnosis or basal narcosis), analgesia (freedom from pain) depression of reflexes, muscle relaxation

Put to sleep

Types of anesthesia careTypes of anesthesia careRegional AnesthesiaRegional Anesthesia

A local anethetic is injected to block or ansthetize a nerve or nerve fibers

Implies a major nerve block administered by an anesthesiologist (such as spinal, epidural, caudal, or major peripheral block)

Types of anesthesia careTypes of anesthesia caremonitered anesthesia caremonitered anesthesia care

Infiltration of the surgical site with a local anesthesia is performed by the surgeon

The anasthesiologist may supplement the local anesthesia with intravenous drugs that provide systemic analgesia and sedation and depress the response of the patient´s autonomic nervous system

Types of anesthesia careTypes of anesthesia carelocal anesthesialocal anesthesia

Employed for minor procedures in which the surgical site is infiltrated with a local anesthetic such as lidocaine or bupivacaine

A perioperative nurse usually monitors the patient´s vital signs

May inject intravenous sedatives or analgesic drugs

PremedicationPremedication Purpose: to sedate the patient and reduce anxiety Classified as sedatives and hypnotics, tranquilizers, analgesic or narcotics and

anticholinergics Antiacid or an H2receptor-blockingdrug such as cimitidine (tagamet) or ranitidine

(Zantac) to decrease gastric acid production and make the gastric contents less acidic

If aspiration occur this premedication decreases the resultant pulmonary damage Given 60-90 minutes before surgery, or may be given i.v. After the pat. arrives in

the surgical suite NPO for a minimum of 6 hours before elective surgery Not given to elderly people or ambulatory patients because residual effects of the

drugs are present long after the pat. have been discharged and gone home

Perioperative monitoringPerioperative monitoringUndergeneral anesthesia: monitoring Inspired oxygen analyzer(FiO2) which calibrated to room air and 100% oxygen on a daily basis Low pressure disconnect alarm, which senses pressure in the expiratory limb of the patient circuit Inspiratory pressure Respirometer (these four devices are an integral part of most modern anesthesia machine ECG BP-automated unit Heart rate Precordial or esophagel stethoscope Temp

Perioperative monitoringPerioperative monitoring

Pulse oximeters End tidal carbon dioxide (ECO2) Peripheral nerve stimulator if muscle relaxants are used Foly catheter For selected patint with a potential risk of venous air

embolism a doppler probe may placed over the right atrium

Invasive: arterial pressure mesurements, central venous pressure

Pulmonary artery catheter and continous mixed venous oxygen saturation measured

Perioperative monitoringPerioperative monitoring

For special conditions other monitors as transesophageal echocardiography

Electroencephalogram Cereral or neurological may be used

Inhalational Anesthetic AgentsInhalational Anesthetic Agents

Inhalational anesthesia refers to the delivery of gases or vapors from the respiratory system to produce anesthesia

Pharmacokinetics--uptake, distribution, and elimination from the body

Pharmacodyamics-- MAC value

Regional AnesthesiaRegional Anesthesia

Defined as “a reversible loss of sensation in a specific area of the body” Spinal anesthesiaEpidural anesthesiaIV Regional BlocksPeripheral Nerve Blocks

Spinal AnesthesiaSpinal Anesthesia

A local anesthetic agent (lidocaine, tetracaine or bupivacaine) is injected into the subarachnoid spaceSpinal anesthesia is also known as a

subarachnoid block

Blocks sensory and motor nerves, producing loss of sensation and temporary paralysis

Possible Complications of Spinal Possible Complications of Spinal

AnesthesiaAnesthesia Hypotension

Post-dural puncture headache (“Spinal headache”) caused by leakage of spinal fluid through the puncture hole in the dura-can be treated by blood patch

“High Spinal”- can cause temporary paralysis of respiratory muscles. Patient will need ventilator support until block wears off

Epidural AnesthesiaEpidural Anesthesia

Local anesthetic agent is injected through an intervertebral space into the epidural space.

May be administered as a one-time dose, or as a continuous epidural, with a catheter inserted into the epidural space to administer anesthetic drug

Dr. Aidah Abu Elsoud Alkaissi Division of Intensive Care and Anaesthesiology University of

Linköping Sweden

Complications of Epidural Complications of Epidural AnesthesiaAnesthesia

Hypotension Inadvertent dural puncture Inadvertent injection of anesthetic into the

subarachnoid space

IV Regional BlocksIV Regional Blocks

Also known as a Bier Block Used on surgery of the upper extremities Patient must have an IV inserted in the

operative extremity

IV Regional BlockIV Regional Block

After a pneumatic tourniquet is applied to extremity, Lidocaine is injected through the IV.

Anesthesia lasts until the tourniquet is deflated at the end of the case.

IV Regional BlocksIV Regional Blocks

IMPORTANT- to prevent an overdose of lidocaine it is important not to deflate the tourniquet quickly at the end of the procedure.

Peripheral Nerve BlocksPeripheral Nerve Blocks

Injection of local anesthetic around a peripheral nerve

Can be used for anesthesia during surgery or for post-op pain relief

Examples: ankle block for foot surgery, supraclavicular block for post-op pain control after shoulder surgery

Monitored Anesthesia Care (MAC)Monitored Anesthesia Care (MAC)

Generally used for short, minor procedures done under local anesthesia

Anesthesia provider monitors the patient and may provide supplemental IV sedation if indicated

Conscious SedationConscious Sedation

Used for short, minor procedures

Used in the OR and outlying areas (ER, GI Lab, etc)

Patient is monitored by a nurse and receives sedation sufficient to cause a depressed level of consciousness, but not enough to interfere with patient’s ability to maintain their airway

Inhalation AnestheticsInhalation Anesthetics

Nitrous Oxide- can cause expansion of other gases- use of N20 contraindicated in patients who have had medical gas instilled in their eye(s) during retinal detachment repair surgery

Inhalation AnestheticsInhalation Anesthetics

Cause cerebrovascular dilation and increased cerebral blood flow

Cause systemic vasodilation and decreased blood pressure

Post-op N&V

All inhalation anesthetics, except N20, can trigger malignant hyperthermia in susceptible patients

Intravenous Intravenous Induction/Maintenance AgentsInduction/Maintenance Agents

Propofol (Diprivan)- pain/burning on injection, can cause bizarre dreams

Pentothal (Sodium Thiopental)- can cause laryngospasm

General AnesthesiaGeneral Anesthesia

During induction the room should be as quiet as possible

The circulator should be available to assist anesthesia provider during induction & emergence

Never move/reposition an intubated patient without coordinating the move with anesthesia first

General AnesthesiaGeneral Anesthesia

Laryngospasm may happen in a patient having a procedure with general anesthesia

When laryngospasm occurs, it is usually during intubation or emergency

Assist anesthesia provider as needed- call for anesthesia back-up if necessary

Difficult Airway CartDifficult Airway Cart

Anesthesia maintains a “Difficult Airway Cart” containing equipment & supplies for difficult intubations

This cart is stored in one of the anesthesia supply rooms

Page anesthesia tech if the cart is needed for your room

Cricoid Pressure or Sellick ManeuverCricoid Pressure or Sellick Maneuver

Used for patients at risk for aspiration during induction, due to a full stomach or other factors such as a history of reflux

Pressure on the cricoid cartilage compresses the esophagus against the cervical vertebrae and prevents reflux

Sellick ManeuverSellick Maneuver

Cricoid pressure is maintained, as directed by anesthesia provider, until the ETT cuff is inflated:

Regional Regional AnesthesiaAnesthesia

Circulator may need to assist anesthesia provider with positioning for spinal or epidural anesthesia.

Patient usually is positioned laterally for placement of regional anesthesia, but may be positioned sitting upright.

The Awake PatientThe Awake Patient

Patients undergoing surgery with regional or local anesthesia, even if sedated, may be aware of conversation and activity in room

Post sign on door to OR, “Patient is Awake” so that staff entering room will be aware that patient is conscious

When Patient is AwakeWhen Patient is Awake

Limit any discussion of patient’s medical condition and prognosis

Avoid discussion of other patients & limit unnecessary conversation-- a sedated patient can easily misinterpret conversation they overhear