“Nothing in life is to be feared.It is only to be understood.”

Marie Curie (`868-1934)

General anesthesia

Regional anesthesia

Monitored anesthesia care

General anesthesia

“Before him surgery was agony.”Epitaph on a monument honoring W. Morton

General anesthesia

The goals of general anesthesia:

- Mandatory: -amnesia/sedation/hypnosis

-analgesia

-maintenance of homeostasis

- Optionally: -muscle relaxation

General anesthesia indications

Indications based on the surgical procedure: -surgical procedures requiring analgesia and

muscle relaxation, that cannot be performed using regional anesthesia techniques: upper abdominal surgery, thoracic surgery, head and neck surgery, shoulder surgery etc.

-surgical procedures that significally interfere with vital functions: neurosurgery, thoracic surgery, cardiac surgery, surgery of the aorta etc.

Indications based on the patient condition: -different pathologies or ongoing treatments that

make the regional anesthesia tachniques contraindicated: the patients with coagulation disorders, anticoagulant treatments, infections or other lesions in the area where a regional anesthesia procedure would be performed;

-systemic diseases with definite functional limitations: the patient with respiratory insufficency, shock, coma, major hydroelectrolytic or acido-basic imbalance.

General anesthesia indications

Drugs used for general anesthesia

HypnosisAnalgesiaMuscle relaxationMaintenance of homeostasis

can all be achieved by administering one or more drugs

Drugs used for general anesthesia• Inhalatory anesthetics:

-gaseous form nitrous oxide

-volatile liquids halothane, isoflurane, sevoflurane si

desflurane

The advantage of entering and leaving the body by ventilation with minimal metabolization.

They result in sedation, analgesia and light muscle relaxation.

The potency of an inhalatory anestheticMAC (minimal alveolar concentration)

= the alveolar concentration of the anesthetic that abolishes the movements caused by the skin incision in 50% of the patients

Each inhalatory anesthetic has its own specific MAC.

Modern anesthesia - new types of MAC:• MAC intubation ( MAC that facilitates the intubation in 50% of the patients);• MAC bar (MAC that abolishes the hemodynamic response in 50% of the

patients);• MAC awake (MAC at which awakening occurs in 50% of the patients).

Inhalant anesthetic

Class Concentration in balanced anesthesia

Advantages/disadvantages Side effects

Nitrous oxide

Gaseous 40-66% Light analgesiaAccumulation in airway spaces

Risk of hypoxemiaEuforia

Halothane Volatile 1,5-2% Bronchodilatation Slow dynamics

Cardio-vascular depression

Isoflurane Volatile 1,5-2% BronchodilatationMedium dynamics

Vasodilatation

Sevoflurane Volatile 2-3% BronchodilatationFast dynamicsCardio-vascular stability

Compound A

Desflurane Volatile 6-8% Airway irritantSpecial vapporiser

Sympathetic stimulation

Intravenous anesthetics:

Short acting:

Barbiturates → metohexital

thiopental, tiamital

Imidazolic compounds → etomidate

Alkylphenols → propofol

Steroids → eltanolone

Long acting:

Ketamine

Benzodiazepines → diazepam, midazolam

THIOPENTAL:

-very rapid induction; maximal effect in 40 s;

-superficial anesthetic sleep;

-NO an analgesic effect;

-weak muscle relaxation.

Administration: slow i.v.

Side effects: risk of respiratory and circulatory depression

PROPOFOL

-very liposoluble fatty acid;

-hepatic metabolisation in great extent → short effect;

Pharmacodynamic action:

-pharmacologic effects similar with those of Thiopental;

-less residual effects.

KETAMINEPharmacodynamic action: Dissociative anesthetic: - dissociation from the environment

- superficial sleep - strong analgesia

Advantages:-No respiratory depressant effect; -hemodynamic stability by the release of

catecholamines -bronchodilatatory effect

Hypnotic Class Induction dose

Single dose duration of action

Side effects

Thiopental Short acting barbituric

2-4 mg/kg 5-10 min Arterial hypotension, respiratory depression, tachycardia, decreases the cardiac output

Propofol Alkylphenol 1-2 mg/kg 5-10 min Arterial hypotension, respiratory depression, tachycardia

Etomidat Imidazolic compound

0,3 mg/kg 5-10 min Adrenal glad inhibition

Diazepam Benzodiazepines 0,3 mg/kg 10-60 min Interindividual response variability

Midazolam Benzodiazepines 0,2-0,3 mg/kg

5-15 min Respiratory depression

Analgetics: Opioids: -the class of analgesics with the broadest intra-

anesthetic utilisation; -profound dose-dependant analgesia; -in spite of their quasi-constant use during general

anesthesia, the opioids are not anesthetics because the loss of consciousness is not a regular effect

-they regularly result in respiratory dose-dependent depression. Cardiovascular depression is a variable effect.

Opioids Class Medium dose

Single dose duration of action

Side effects

Morphine μ Agonist 0,2 mg/kg 30-60 min Respiratory depression, sedation. hTA, bradycardia

Pethidine μ/Δ Agonist

1 mg/kg 20-30 min Sedation, nausea/vomiting, HTA, tachycardia

Fentanil μ Agonist 5-15 μg/kg 20 min Respiratory depression

Sufentanil μ Agonist 0,3-1 μg/kg

Respiratory depression

Alfentanil μ Agonist 5-50 μg/kg Respiratory depression

Remifentanil

μ Agonist 0,5-1 μg/kg

1-3 min Respiratory depression

Buprenorphine

Agonist/ antagonist

0,3 mg 3-4 ore Ceilling effect

Muscle relaxants: -substances that act at the neuromuscular junction

level and prevent the transmission of the physiologic stimulus for the muscular contraction;

-NO action on the CNS, NO loss of consciousness, NO analgesia;

-utilized for the facilitation of the airway instrumentation, of mechanical ventilation and of the surgical intervention;

-results in alveolar hypoventilation or apnea by the action on the respiratory muscles;

-minimal cardio-vascular effects.

Muscular relaxant

Class Intubation dose

Single dose duration of action

Particular instructions

Succinylcholine

D 1-1,5 mg/kg 10-15 min Full stomach

Pancuronium ND 0,1 mg/kg 30-40 min Bradycardia

Vecuronium ND 0,08 mg/kg 20-30 min Cardiac affections

Atracurium ND 0,5 mg/kg 20 min Kidney failure

Cisatracurium ND 0,2 mg/kg 20 min Kidney failure

Mivacurium ND 0,2 mg/kg 10-15 min Short interventions

Rocuronium ND 0,6-0,9 mg/kg 30-60 min Full stomach

Anesthesia apparatus

Anesthesia Apparatus

Components: -connection with the sources of medical fluids -flowmeters -vaporizers -anesthetic circuit -CO2 scavenger system -balloon ventilation system -overpressure valve -mechanical ventilation module -emergency oxygen delivery circuit

-ventilation parameters setting module;

-ventilation parameters and inhalation anesthetics monitoring module;

-alarm module;

-vacuum system (sucction).

Intraanesthesic monitoring

Intraanesthesic monitoring Standard I: -the presence in the room of an anesthesiologist or

a qualified staff member throughout the duration of the anesthesia.

Standard II: -oxygenation: inspiratory oxygen concentration

(FiO2), pulsoxymetry (SpO2); -ventilation: clinical evaluation, auscultation,

capnography; -circulation: electrocardioscopy (continuous),

noninvasive arterial blood pressure and pulse measurement;

-body temperature.

Monitoring

Respiratory Airway pressure, tidal volume, minute ventilation, respiratory rate, O2/CO2 inspiratory concentration, concentration of volatile anesthetic agent, pulsoxymetry

Cardiovascular Non-invasive arterial pressure, multiple leads ECG, computerized analysis of ST segment, central venous pressure, pulmonary artery pressure (systolic, medium, diastolic, wedge) cardiac output, extra-vascular pulmonary water, peripheral vascular resistance, ScvO2, SvO2.

Hypnosis BIS (bispectral index)

Muscle relaxation Peripheral nerve stimulator

Renal Diuresis

Temperature Central, peripheral

Acid - base equilibrium

Blood gas analysis

Electrolytes Na, K, Cl, Ca

Haematological analysis, coagulation studies

Platelets, aPTT, INR

Oxygen transportation

Hb, Ht, cardiac output, SaO2, PaO2

Metabolic Glucose

Preanesthetic visit

Preanesthetic exam:

-psychological preparation of the patient;

-clinical and laboratory evaluation of the patient;

-asignement to an anesthetic risk group (ASA scale)

-choosing the anesthetic technique and obtaining the informed consent;

-set up of an anesthetic plan.

Risk I Patient without systemic diseases

Risk II Patient with systemic diseases without functional limitation

Risk III Patient with systemic diseases with functional limitation

Risk IV Patient with uncompensated systemic disease

Risk V Dying patient

Risk VI Brain dead patient, organ donor

E Emergency procedure

Optimizing the patient status:

-the correction of dysfunctions and diseases in the preoperative period.

Premedication :

-reduced anxiety and reduced need for intra-operative anesthetics;

-decreasing certain risks (parasympathetic reflexes, the risk of aspiration);

-the facilitation of postoperative analgesia.

Phases of general anesthesia Induction phase: -the period of transition from the state of conscious to the

state of general anesthesia; -CNS depression, ventilatory, cardiovascular depression,

muscle relaxation; -securing the airway. Maintenace phase: -providing the adequate depth of anesthesia by

administering anesthetics, analgesics and muscle relaxant agents.

Emergency phase: -the interruption of the administration of all volatile or

intravenous anesthetic agents; -the antagonisation of the muscle relaxant drug.

General anesthesia techniques

Balanced anesthesia; Intravenous anesthesia; Volatile anesthesia; Combined techniques of general and regional

anesthesia:

-general anesthesia + epidural anesthesia.

General anesthesia complications

Respiratory Hypoxemia, hypercapnia laryngeal spasm, bronchospasm, aspiration, ARDS, atelectasis

Cardio-vascular High/low blood pressure, tachy/bradycardia, myocardial ischemia, arrhythmia , hypovolemia, low cardiac output

CNS Convulsions, shivers, post anoxic encephalopathy, paresis by compression or elongation of peripheral nerves

Digestive Vomiting or regurgitation, hiccup

Renal Oligo/anuria, urinary retention, pre - renal failure

Metabolice Hyper/hypoglycemia, malignant hyperthermia

Hidro-electrolitics Extracellular space expansion (interstitial oedema), hypo/hyperkalemia, hypocalcemia

Acid-base Hypercloremic metabolic acidosis, lactacidemic

Coagulation Thrombocytopenia, dilutional coagulopathy, deep venous thrombosis

Allergical Cutaneous eruptions, Quincke oedema, bronchospasm, anaphylactic shock

Cutaneous Decubitus injury, accidental burns

Regional anesthesia Subarachnoid (spinal) Epidural Sequential Caudal

Regional anesthesia Indications: -the area can be anesthetised using regional blocks; -the surgical procedure does not affect the vital

functions; -patient's informed consent; Contraindications: -patient's refusal; -active coagulation disorders or anticoagulant

treatment; -infections or haematoma at injection site; -neurological deficit and lack of cooperation.

Spinal Anethesia:

analgesia

muscle relaxation

sympathetic blockade -sympathetic blockade: hypotension, bradycardia,

urinary retention;

-hypovolemia is an absolute contraindication of spinal anesthesia;

-epidural analgesia is the standard procedure for peripartum analgesia;

-complications: systemic (high spred of anesthetic- total spinal anesthesia or systemic toxicity), headache.

Local anestheticsAmides Esters

Lidocain Prilocain Procain

Mepivacain Etidocain Tetracain

Bupivacain Ropivacain Benzocain

Clinical use of local anesthetics

Central regional anesthesia/analgesia

Regional intravenous anesthesia

Peripheral nerve block or plexus

Infiltration anesthesia

Local anesthesia

Blocking of thehemodynamic response during tracheal intubation

in regional anesthesia we frequently use the combination between a local anesthetic and adrenaline, an opioid or clonidine, increasing the duration and quality of the block

During regional anesthesia – mandatory equipments:Anesthesia delivery systemEquipments and materials for airway managementOxygen sourceMonitoring: ventilation, oxygenation, circulation, blood

pressure, EKG.

Spinal anesthesia (sub-arachnoid block)

Epidural anesthesia

Sequential (combined) anesthesia

spinal / epidural

Caudal anesthesia

Plexus anesthesia or peripheral nerves blockadeSingle-shotCatheter

Local anesthesiacontacttopical - skin, mucous membrane application tissue infiltration

Monitored anesthesia care

Monitored anesthesia care - intravenous administration of anxiolytic, sedative,

analgesic and amnesic drugs either isolated or supplementing a regional anesthesia procedure;

- indicated in: painful diagnostic or therapeutic procedures or supplementing a inappropiate regional block;

- the CPR equipments must be close-by at all times; - complications: respiratory depression with

hypoventilation and loss of airway protection.