anesthesia

AnesthesiaDR.MUHAMMAD ASIM BAJWAASISSTANT PROFESSORDEPT.OF ANESTHESIA AND ICUUNIVERSITY OF LAHORE

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

AnesthesiaFrom Greek anaisthesis means not sensationListed in Baileys English Dictionary 1721.When the effect of ether was discoveredanesthesia used as a name for the new phenomenon.

Basic Principles of AnesthesiaAnesthesia defined as the abolition of sensationAnalgesia defined as the abolition of painTriad of General Anesthesianeed for unconsciousnessneed for analgesianeed for muscle relaxation

History of Anesthesia

History of AnesthesiaEther synthesized in 1540 by CordusEther used as anesthetic in 1842 by Dr. Crawford W. LongEther publicized as anesthetic in 1846 by Dr. William MortonChloroform used as anesthetic in 1853 by Dr. John Snow

History of AnesthesiaEndotracheal tube discovered in 1878Local anesthesia with cocaine in 1885Thiopental first used in 1934Curare 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 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 thereComplication such as difficult airway management? Does the patient have risk factor for difficult airway management?

Creating the Anesthesia Plan

After the preoperative evaluation, the anesthesia plan canbe completed. The plan should list drug choices and dosesin 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 Room

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

Anesthesia ProvidersAnesthesiologist ( 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 physicianCRNA must have 2 years of training in anesthesia

Patient SafetyPatient 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 evaluationAnaesthesiologist: reviews the patients 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 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 anesthesiaThe patients understanding and wishes regarding the type of anesthesia that could be usedThe type and duration of the surgical procedureThe patientss physiologic status and stabilityThe presence and severity of coexisting diseaseThe patients mental and psychologic statusThe postoperative recovery from various kinds of anesthesiaOptions for management of postoperative painAny particular requiremets of the surgeonThere is major and minor surgery but only major anesthesia

Types of anesthesia careGeneral AnesthesiaReversible, unconscious state is characterised by amnesia (sleep, hypnosis or basal narcosis), analgesia (freedom from pain) depression of reflexes, muscle relaxationPut to sleep

Types of anesthesia careRegional AnesthesiaA local anethetic is injected to block or ansthetize a nerve or nerve fibersImplies a major nerve block administered by an anesthesiologist (such as spinal, epidural, caudal, or major peripheral block)

Types of anesthesia caremonitered anesthesia careInfiltration 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 patients autonomic nervous system

Types of anesthesia carelocal anesthesiaEmployed for minor procedures in which the surgical site is infiltrated with a local anesthetic such as lidocaine or bupivacaineA perioperative nurse usually monitors the patients vital signs May inject intravenous sedatives or analgesic drugs

Premedication

Purpose: to sedate the patient and reduce anxietyClassified as sedatives and hypnotics, tranquilizers, analgesic or narcotics and anticholinergicsAntiacid or an H2receptor-blockingdrug such as cimitidine (tagamet) or ranitidine (Zantac) to decrease gastric acid production and make the gastric contents less acidicIf aspiration occur this premedication decreases the resultant pulmonary damageGiven 60-90 minutes before surgery, or may be given i.v. After the pat. arrives in the surgical suiteNPO for a minimum of 6 hours before elective surgeryNot 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 monitoringUndergeneral anesthesia: monitoringInspired oxygen analyzer(FiO2) which calibrated to room air and 100% oxygen on a daily basisLow pressure disconnect alarm, which senses pressure in the expiratory limb of the patient circuitInspiratory pressureRespirometer (these four devices are an integral part of most modern anesthesia machineECGBP-automated unitHeart ratePrecordial or esophagel stethoscopeTemp

Perioperative monitoringPulse oximetersEnd tidal carbon dioxide (ECO2)Peripheral nerve stimulator if muscle relaxants are usedFoly catheterFor selected patint with a potential risk of venous air embolism a doppler probe may placed over the right atriumInvasive: arterial pressure mesurements, central venous pressurePulmonary artery catheter and continous mixed venous oxygen saturation measured

Perioperative monitoringFor special conditions other monitors as transesophageal echocardiographyElectroencephalogramCereral or neurological may be used

Inhalational Anesthetic AgentsInhalational anesthesia refers to the delivery of gases or vapors from the respiratory system to produce anesthesiaPharmacokinetics--uptake, distribution, and elimination from the bodyPharmacodyamics-- MAC value

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

Spinal 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 Anesthesia 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 AnesthesiaLocal 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

Complications of Epidural AnesthesiaHypotensionInadvertent dural punctureInadvertent injection of anesthetic into the subarachnoid space

IV Regional BlocksAlso known as a Bier BlockUsed on surgery of the upper extremitiesPatient must have an IV inserted in the operative extremity

IV Regional BlockAfter 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 BlocksIMPORTANT- to prevent an overdose of lidocaine it is important not to deflate the tourniquet quickly at the end of the procedure.

Peripheral Nerve BlocksInjection 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)Generally used for short, minor procedures done under local anesthesiaAnesthesia provider monitors the patient and may provide supplemental IV sedation if indicated

Conscious SedationUsed 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 patients ability to maintain their airway

Inhalation AnestheticsNitrous 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 AnestheticsCause 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 Induction/Maintenance AgentsPropofol (Diprivan)- pain/burning on injection, can cause bizarre dreams

Pentothal (Sodium Thiopental)- can cause laryngospasm

General AnesthesiaDuring 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 AnesthesiaLaryngospasm 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 CartAnesthesia 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 ManeuverUsed 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 Maneuver Cricoid pressure is maintained, as directed by anesthesia provider, until the ETT cuff is inflated:

Regional AnesthesiaCirculator 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 PatientPatients 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 AwakeLimit any discussion of patients medical condition and prognosis

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

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anesthesia

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