[D159] L8 COMMONLY USED GASES AND DRUGS IN CONSCIOUS SEDATION

Prevent possible vomiting due to Gi irritation of some drugs and prevent possible aspiration

Why are patients placed on NPO PMN before general anesthesia?

1. ENFLURANE

2. HALOTHANE

3. SEVOFLURANE

4. ISOFLURANE

5. DESFLURANE

What are the general anesthetic gases?

• Orange bottle

• Nonflammable liquid

• Clear, colorless, stable

• PURITY EXCEEDS 99.9%

• LOWERS SEIZURE THRESHOLD

  • can trigger epileptic attacks for some patients

Describe ENFLURANE

• Red bottles

• Arrythmias can be precipitated with the administration of ADRENALINE

• less popular due to better gases

describe HALOTHANE

• yellow bottles

• sweet-smelling, nonflammable, non-clear colorless liquid

Describe SEVOFLURANE

• purple bottles

• mildly pungent, musty, ethereal odor

• induction with isoflurane in oxygen or in combination with oxygen-nitrous oxide mixtures may produce COUGHING, BREATH HOLDING, LARYNGOSPASM

  • avoided by use of a HYPNOTIC DOSE of an ultra short acting barbiturate

describe ISOFLURANE

• blue bottle

• Colorless, volatile liquid below 22.8 C

• slight pungent smell

• rapid onset

• expensive, less used in 3rd world countries

describe DESFLURANE

• slight decrease in intellectual function for 2-3 days

• changes in moods and symptoms for up to 6 days

drawbacks of general anesthesia?

MALIGNANT HYPERTHERMIA

skeletal hypermetabolic state that is triggered by the inhalation of anesthetic agents

• complication seen with gaseus agents

• inhalation of anesthetic agents may trigger a SKELETAL MUSCLE HYPERMETABOLIC STATE

• leads to high oxygen demand

• corrected by IV DANTROLENE SODIUM and SUPPORTIVE THERAPY

describe malignant hyperthermia

• hypercapnia

• muscle rigidity

• tachycardia

• tachypnea

• cyanosis

• arrythmias/unstable blood pressure

symptoms of MALIGNANT HYPERTHERMIA

ICE WRAP

in worst case scenarios, to control hyperthermia in malignant hyperthermia, what do you do?

1. LARYNGOSCOPE - opens mouth and airwat to insert endotracheal tube

2. VAPORIZER - liquid turn to gas

3. VENTILATOR - breathes for patient

4. CARDIAC MONITOR - monitors bp, pulse rate, o2 saturation, respiratory rate

5. CAPNOGRAPH - monitors co2

6. PULSE OXIMETER - oxygen saturation

7. DEFIBRILLATOR

8. ANESTHESIA MACHINE

What are the equipment used in general anesthesia?

CLASS I

• soft palate

• uvula

• fauces

• pillars

CLASS II

• soft palate

• uvula

• fauces

CLASS III

• soft palate

• uvula

CLASS IV

• hard palate

what can you see in each mallampati score

CLASS I AND II CAN BE CONSCIOUSLY SEDATED, CLASS III AND IV HAS TO BE GA WITH INTUBATINON

Which mallampati class has to be GA and which can be consciously sedated

1. BENZODIAZEPINES

2. BARBITURATES

3. ANTIHISTAMINES

4. NARCOTICS

5. ANTICHOLINERGICS/VAGOLYTICS/ANTISIALOGOGUES/ BELLADONA DERIVATIVES

6. DISSOCIATIVE ANESTHETICS

Types of agents used in conscious sedation

1. diazepam

2. midazolam

3. benzodiazepam

TYPEs of benzodiazepines

diazepam - benzodiazepine

• 40% propylene glycol - miscible w blood; irritant - burning sensation

• 10% ethyl alcohol

• 5% Na Benzoate % Benzoic acid - buffer

• 1.5% Benzyl alcohol - preservative

• pale yellow odorless powder - iv drug

chemical nature of diazepam

AVAILABILITY → 10mg/2ml

AVERAGE DOSE →10-12mg

PEAK → 1-2 MIN

DURATION → a - 45 min; B - 30 H

1. Acts on hippocampus;anticonvulsant

2. Enhances action of gamma-amino butyric acid

3. No direct effect on BP or CO

4. Potential respiratory depressant

5. Can cause congenital malformation

Pharmacology of diazepam

• allergy

• acute angle glaucoma

contraindications of diazepam

VERRILS SIGN

50% ptosis

• white colorless crystal in aqueous soln

• water soluble

• no propylene glycol

• avail. in tablet and iv form

chemical nature of midazolam

1. no rebound effect

2. a half life - 4-18 min; B half life 1.7-2.4H

3. ONSET 1-2 ½ min

4. best used within 30 minutes

5. may have retrograde amnesia

pharmacology of midazolam

• aka. SEDATIVE HYPNOTICS

• anticonvulsant

• CNS depressant on reticular activating system

• decreases pain thresholf

• respiratory and cardiovascular depressant

  • C/I with pregnant and asthmatic px

• “overhang” feeling

describe BARBITURATES

1. ULRA-SHORT ACTING

   1. peak - 30 sec

   2. dose 5-150mg

   3. DURATION 5-7MIN

   4. thiopental NA , methohexital NA

2. SHORT ACTING

   1. peak - 30 sec

   2. dose 5-150mg

   3. DURATION 2-4 H

   4. pentobarbital, secobarbital

3. LONG & INTERMEDIATE ACTING

classification of barbiturates

PROPOFOL

milk of amnesia

• short acting, IV administered

• affects GABA

• C/I allergy to soybean and egg due to soybean oil and egg lecithin content

• DOSE 2-2.5 mg/kg

• PACJAGING 10mg/ml

Describe propofol

ANTIHISTAMINE

side effect of this drug is sedation

1. PROMETHAZINE 4 - 6 H

2. DIPHENHYDRAMINE

For both:

AVAILABILITY - 50mg/ml

AVE DOSE - 25-50mg

What are the antihistamines that can be sedatives

NARCOTICS

used to control moderate / svere pain

increases px pain threshold

1. MEPERIDINE

2. MORPHINE

3. FENTANYL

4. NALBUPHINE

examples of narcotics

NARCOTIC

• may decrease salivary flow, increase heart rate (for doses higher than used for analgesia)

• peoduce localized histamine release to cause “tracking”

• onset - 2-4m

• duration - 30-45m

• availability - 100mg/ml

• dose - 37.5 - 50mg

describe MEPERIDINE

NARCOTIC

• C/I for asthmatics, allergies, COPD, MAO inhibitor

• onset - 2-4m

• duration - 2H

• availability - 2,4,8, 10 ,15 mg/ml

• dose - 5-6mg

describe MORPHINE

NARCOTIC

• can cause muscle rigidity in rapid infusion

  • SUccinylcholine: antidote for rigidity

• onset - <1m

• duration - 30-60m

• availability - 0.5mg/2ml

• dose - 0.05 - 0.06mg

describe FENTANYL

NARCOTIC

• narcotic agonist-antagonist

• not combined w diazepam — will produce milky white precipitate

• onset - 2-3m

• duration - 3-6H

• availability - 10mg/ml

• dose - 7-8mg

describe NAMBUPHINE

ANTICHOLINERGICS

used in CS to decrease salivary flow

1. ATROPINE

2. SCOPOLAMINE

3. GLYCOPYROLATE

types of anticholinergics

ANTICHOLINERGIC

• stimulate medulla

• causes rash like appearance - vasodilation of BV - ATROPINE FLUSH

• availability - 10mg/ml

• dose - 0.4-0.6mg

describe ATROPINE

ANTICHOLINERGIC

• paralyzed oculi muscleS

• availability - 10mg/ml

• dose - 0.3 mg

describe SCOPOLAMINE

ANTICHOLINERGIC

• antisialogogue effect up to 7 h

• can cause mydriasis and cycloplegia

• C/I - for those w glaucoma

• availability - 0.2mg/ml

• dose - 0.1 mg

descibe GLYCOPYROLATE

KETAMINE

• onset - 1m

• duration - 10m

• availability - 10,50,100mg/ml

• dose - 1-4.5mg/kg

type of dissociative anesthetic

NALOXONE

• for overdose or reversal of narcotic analgesics

• SC, IM, IV

• C/I → drug addicts

• DURATION - 30min

• availability - 0.02, 0.4, 10mg/ml

• dose - 0.4mg (adult) / 0.01mg/kg

narcotic antagonist

FLUMAZENIL

• reverse effects of benzodiazepines

• competitively inhibits activity of GABA/benzodiazepine receptor complec

• onset - 1-2m

benzodiadepine antagonist

PHYSOSTIGMINE

• reversible cholinesterase and increase concentration of acetylcholine

• inhibits actioi of anticholinergic drugs

• C/I in asthmatics, diabetics, CVS disorders, mechanical obstruction GIT and GUT

• availabilty - 1mg/ml

• dose - 0.5-2mg

ANTI-EMERGENCE DELERIUM DRUG

ATROPINE

antidote for ovedose of physostigmine

JORGENSENS TECHNIQUE

combination of a sedative, narcotic agent, and antisialogogue in concsious sedation