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Preoperative

medications

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3 types of pre op meds:

� Sedatives / Depressants / Hypnotics Drugs

� Anticholinergics

� Narcotics / Opiates / Opiods

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Sedatives / depressants / hypnoticdrugs

Sedatives ² cause sedation ( mildest fromCNS depression ´rest and relaxationµ)

Hypnotics effect- a form natural sleepHypnotic drugs are those meant to cause

sleepiness or promote calm, and they mayalso be called sedative hypnotic drugs.These medicines can vary to the degreethey are effective and may also vary in thelevel of sedation or sleepiness they causegiven dosage and individual patientresponse.

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Types:

� BARBITURATES (minor tranquilazers)

increase potential for physical and mental

dependencyuse to induce sleep and reduced anxiety

drugs that have suffix ´talµ

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Types of barbiturates:

a) Ultra short acting used as a general anesthetic agent example: Thiopental sodium and methohexital sodium

b) Short acting

Are use to induce sleep example: secobarbital and phentobarbital

c) Intermidiate acting use as a sleep sustainers or use to maintain a sleep

(nocturnal awakening) example: Amobarbital, aprobarbital and butabarbital

d) Long acting Use to control seizure and epilepsy example: phenobarbital and mephobarbital

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� BENZODIAZEPINE M

inor tranquilizers of anxiolytics Use induce sleep and reduce anxiety

Less potential per drug dependence

Drugs that have suffix ´pamµ

Example :

Diazepam Temazepam

Lorazepam

Midazolam

Triazolam

Estazolam Aprazolam

Flurazepam

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� NON-BARBITURATES & NON-

BENZODIAZIPINES Antihistamine Example:

Diphenhydramine Hydroxyzine Promethazine

Zolpidem Use for short tern treatment of insomnia

Piperidinediones Resemble barbiturates

Can cause vasomotor colapse and serious blooddyscrasia

Chloral hydrate Use to induse sleep and decrease noctural awakenings

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anticholinergics

� secretions� Saliva

� Sweat

� Urine

� counteracts:� General Anesthesia = HR , RR

� IV Anesthesia = laryngospasm, bronchospasm

� Example :� Atropine Sulfate

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Narcotics / opiates / opiods

� an addictive drug, such as opium, that reduces pain, altersmood and behavior, and usually induces sleep or stupor

� a pain releiver , and also called analgesics

�

for moderate to severe pain of smooth muscles, organs andbones

� suppress pain, respiration and coughing

� act on central nervous system

� more potent than non narcotic analgesics

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� Opiate agonists:

1. Morphine

- an extraction from opium- effected in relieving severe pain and can alsosuppress cough and respiration

2. Codein- not as potent as morphine

- has analgesic and antitussive effect

3. Other opiate agonist- hydrocodone- oxycodone- hydromorphone

- meperidine ( has no antitussive effect)- sufentanil- fentanyl- methadone

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Adverse Effect- respiratory depression- orthostatic hypotension

- tolerance- dependence

� Opiate Partial Agonist1. Nalbuphine2. butorphanol

3. buprenorphine

� Opiate Antagonist- antidote for narcotic analgesic excess or overdose1. Naloxone2. naitrexone

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Types of anesthesia

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General anesthesia

� Analgesia ³ loss of response to pain

� Amnesia ³ loss of memory

� Immobility ³ loss of motor reflexes

� Hypnosis ³ loss of

consciousness� Skeletal muscle relaxation

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Administration techniques :

� Mask inhalation ² anesthetic gas or vapor of avolatile liquid is inhaled through a face maskattached to the anesthesia machine by breathingtubes

� Laryngeal mask ² insertion of laryngeal maskinto the larynx

� Endotracheal administration ² anesthetic gas isinhaled directly into the trachea through a nasal

or oral tube inserted between the vocal cords bydirect laryngoscopy

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Stages of G.A :

� STAGE I (stage of anesthesia/ induction stage

Begins with consciousness and endswith loss of consciousness.

Speech is difficult

Sensation of smell and pain are lost

Dreams, auditory and visualhallucinations may occur

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� STAGE ll (Excitement/

Delirium stage )Produces a loss of consciousness

caused by depression of the Cerebralcortex confusion

excitement or delirium occur

� Stage lll (Surgical Stage)

Surgical Procedure Is performedDuring This Stage.

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� STAGE lV (Medullary Paralysis Stage )

Toxic stage Of anesthesiaRespiration are lost

Circulatory collapse occurs

Ventilatory assistance assistance isnecessary

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Inhalation anesthesia

� Inhalation is a controlled method of administrationbecause uptake and elimination of anesthetic agentsare accomplished mainly by pulmonary ventilationand selective organ metabolism. The anesthetic

vapor of a volatile liquid or an anesthetic gas isinhaled and carried into the bloodstream by passingacross the alveolar membrane into the generalcirculation and on the tissues.

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Agents :

� GAS

NITROUS OXIDE (laughing Gas)

absorbed quickly and eliminated rapidly

Has rapid action

CYCLOPROPANE

Absorbed quickly and eliminated rapidly.

Has rapid action High flammable

(no longer used)

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ETHER

Highly flammable,has no severe effect

on the liver and CVS

� VOLATILE Liquids

HALOTANE

Noinflammable alternative ,Highlypotent and with rapid recovery

ISOFLURANE

ENFLURANE

DESFLURANE

SEVOFLURANE

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Adverse effect

Respiratory Depression

Hypotension

Dysrhythmias

Hepatic Dysfunction

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Balanced anesthesia� a highly variable technique of general anesthesia using narcotic

analgesics, muscle relaxation, and minimal inhalation agent andnitrous oxide to render the patient unconscious.

� anesthesia that balances the depressing effects on the motor,sensory, reflex and mental aspects of nervous system function bythe anesthetic agents. The philosophy encourages the use of severalagents, each designed to affect one of the functions.

� is the technique in which a number of different agents arecombined to produce a desired effect. This implies a fullunderstanding of physiology and pharmacology. It necessitates athorough clinical knowledge of the methods of administration and itrequires the ability to manage the patient before, during, and afterthe administration of anesthesia. Thus, in a balanced anesthetictechni, anesthesia is produced by using several drugs, often

administered by different routes, which can be detoxified andexcreted in different ways.

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There are five specific advantages to a balancedanesthetic technique:

1. Drugs can be selected and administered in a way whichmakes this service almost universally acceptable.

2. The patient's metabolism undergoes a minimal amountof disturbance and is often better protected than in othertechniques.

3. The patient usually undergoes a shorter and uneventfulpostoperative course.

4. The operator may be provided with more ideal operating

conditions.

5. The operator can usually manage patients with seriousorganic complications with a wider range of safety.

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Spinal anesthesia

� is induced by injecting small amounts of local anaestheticinto the cerebro-spinal fluid (CSF). The injection is usuallymade in the lumbar spine below the level at which thespinal cord ends (L2). Spinal anaesthesia is easy to

perform and has the potential to provide excellentoperating conditions for surgery below the umbilicus. If the anaesthetist has an adequate knowledge of therelevant anatomy, physiology and pharmacology; safeand satisfactory anaesthesia can easily be obtained to themutual satisfaction of the patient, surgeon and

anaesthetist.

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Advantages :

Cost. Anaesthetic drugs and gases are costly and the latteroften difficult to transport. The costs associated with spinalanaesthesia are minimal.

Patient satisf action. If a spinal anaesthetic and the ensuingsurgery are performed skilfully, the majority of patients are

very happy with the technique and appreciate the rapidrecovery and absence of side effects.

Respiratory disease. Spinal anaesthesia produces fewadverse effects on the respiratory system as long as undulyhigh blocks are avoided.

Patent airway. As control of the airway is not compromised,there is a reduced risk of airway obstruction or theaspiration of gastric contents. This advantage may be lost if too much sedation is given.

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Diabetic patients. There is little risk of unrecognised hypoglycaemia in anawake patient. Diabetic patients can usually return to their normal food andinsulin regime soon after surgery as they experience less sedation, nauseaand vomiting.

Muscle relaxation. Spinal anesthesia provides excellent muscle relaxationfor lower abdominal and lower limb surgery.

Bleeding. Blood loss during operation is less than when the same operationis done under general anaesthesia. This is because of a fall in blood pressureand heart rate and improved venous drainage with a resultant decrease inoozing.

Splanchnic blood flow. Because it increases blood flow to the gut, spinalanaesthesia may reduce the incidence of anastomotic dehiscence.

Coagulation. Post-operative deep vein thromboses and pulmonary emboliare less common following spinal anesthesia.

Visceral tone. The bowel is contracted during spinal anesthesia andsphincters are relaxed although peristalsis continues. Normal gut functionrapidly returns following surgery.

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Disadvantages :

Sometimes it can be difficult to find the dural space andoccasionally, it may be impossible to obtain CSF and thetechnique has to be abandoned. Rarely, despite anapparently faultless technique, anaesthesia is not obtained

Hypotension may occur with higher blocks and the

anaesthetist must know how to manage this situation withthe necessary resuscitation drugs and equipmentimmediately to hand. As with general anaesthesia,continuous, close monitoring of the patient is mandatory.

Some patients are not psychologically suited to be awake,even if sedated, during an operation. They should be

identified during the preoperative assessment. Likewise,some surgeons find it very stressful to operate on consciouspatients.

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Indications :

� Spinal anaesthesia is best reserved foroperations below the umbilicus e.g. herniarepairs, gynaecological and urologicaloperations and any operation on the perineumor genitalia. All operations on the leg arepossible, but an amputation, though painless,may be an unpleasant experience for an awakepatient. In this situation it may be appropriate

to combine the spinal with a light generalanaesthetic.

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Contraindication :

Inadequate resuscitation drugs and equipment. Noregional anaesthetic technique should be attempted if drugs and equipment for resuscitation are not immediatelyto hand.

Clotting disorders. If bleeding occurs into the epidural

space because the spinal needle has punctured an epiduralvein, a haematoma could form and compress the spinalcord. Patients with a low platelet count or receivinganticoagulant drugs such as heparin or warfarin are at risk.Remember that patients with liver disease may haveabnormal clotting profiles whilst low platelet counts as wellas abnormal clotting can occur in pre-eclampsia.

Children. Although spinal anaesthesia has beensuccessfully performed on children, this is a highlyspecialised technique best left to experienced paediatricanaesthetists.

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Sepsis on the back near the site of lumbar puncture lestinfection be introduced into the epidural or intrathecal space.

Septicaemia. If a patient is septicaemic, they are at increasedrisk of developing a spinal abscess. Epidural abscesses can,however, appear spontaneously in patients who have not hadspinal/epidural injections especially if they are immuno-deficient: e.g., patients with AIDS, tuberculosis, and diabetes.

Anatomical deformities of the patient's back. This is a relative

contraindication, as it will probably only serve to make the duralpuncture more difficult.

Neurological disease. The advantages and disadvantages of spinal anaesthesia in the presence of neurological disease needcareful assessment. Any worsening of the disease post-operatively may be blamed erroneously on the spinal

anaesthetic. Raised intracranial pressure, however, is an absolutecontra-indication as a dural puncture may precipitate coning of the brain stem.

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Physiology :

� Local anaesthetic solution injected into the subarachnoidspace blocks conduction of impulses along all nerves withwhich it comes in contact, although some nerves are moreeasily blocked than others. There are three classes of nerve:motor, sensory and autonomic. Stimulation of the motornerves causes muscles to contract and when they are

blocked, muscle paralysis results. Sensory nerves transmitsensations such as touch and pain to the spinal cord andfrom there to the brain, whilst autonomic nerves controlthe calibre of blood vessels, heart rate, gut contraction andother functions not under conscious control.

� Generally, autonomic and sensory fibres are blockedbefore motor fibres. This has several importantconsequences. For example, vasodilation and a drop inblood pressure may occur when the autonomic fibres areblocked and the patient may be aware of pressure ormovement and yet feel no pain when surgery starts.

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Intravenous anesthesia :

� Given 1st following by gas anes.

� Decrease vomiting

�

Treat :± Hypotension

± Laryngospasm

± Bronchospasm

± Respiratory arrest

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types

� Thiopental Na

± Penthotal Na

�

Ketamine± Ketalar

� Fentanyl

± innovar

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Regional / local anesthesia

� is anesthesia affecting only a large part of the body, such as a limb.

� Regional anaesthetic techniques can be divided into central andperipheral techniques. The central techniques include so calledneuroaxial blocks (epiduralanaesthesia, spinal anesthesia). The

peripheral techniques can be further divided into plexus blockssuch as brachial plexus blocks, and single nerve blocks. Regionalanaesthesia may be performed as a single shot or with acontinuous catheter through which medication is given over aprolonged period of time, e.g. continuos peripheral nerve block.

� can be provided by injecting local anaesthetics directly into the

veins of an arm (provided the venous flow is impeded by atourniquette.) This is called intravenous regional techniques (bierblock). Regional anaesthesia generally involves the introductionof local anesthetics to block the nerve supply to a specific part of the body, such as a limb, so patients cannot feel pain

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Types

� Topical / Local ² ´caineµ

� Infiltration

±

Nerve block (local) = injected inmuscle near the nerve

± Epidural (CS)

± Caudal (CS)

± Pudendal (NSD) = 2nd stage of laborbefore episiotomy

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indication

� Regional anesthesia may provide anesthesia(absence of feeling, including pain) to allowa surgical operation, or provide post-operativepain relief. Various brachial plexus block exist

for shoulder and arm procedures. Methods similarto routine regional anesthetic techniques are alsooften used for treating chronic pain.

� In labor and childbirth, epidural or combined

spinal epidurals provide effective pain relief.Regional anesthesia is now more common thangeneral anesthesia for caesarian sectionprocedures.

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complication

� Unlike a minor local anesthetic infiltration to allow a wound to be sutured, or a skin

lesion to be excised, regional anesthesia may involve large doses of local

anesthetic, or administration of the local anesthetic very close to, or directly into

the central nervous system. Therefore there is a risk of complications from local

anesthetic toxicity (such as seizures and cardiac arrest) and for a syndrome similar

to spinal shock.

� Most regional anesthetic techniques, even in expert hands, have a failure rate of 1²

10%. Therefore general anesthesia may become necessary even when a procedure

was initially planned to be conducted under a regional technique.

� For these reasons, regional anesthesia is only ever conducted in an environment

that is fully equipped and staffed to provide safe general anesthesia should this be

needed.

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The end

� BSN Irr3

± Bula,Monesa Bianca

± Arruiza, Sheree Ann

± Cardenas, Jonna

± Coronado, Ronald Allan

± Cortezano, Allyza

± Dela Rea, Vanice Joy

± Villanueva,Maria Stella Mariz

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