Anesthesia

1. Anesthesia

2. “Nothing in life is to be feared. It is only to be understood.” Marie Curie (`868-1934)

3. Anesthesia General anesthesia Regional anesthesia Monitored anesthesia care

5. General anesthesia

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

9. General anesthesia The goals of general anesthesia: - Mandatory: -amnesia/sedation/hypnosis -analgesia -maintenance of homeostasis - Optionally: -muscle relaxation

10. 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.

12. General anesthesia indications • 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.

14. Drugs used for general anesthesia Hypnosis Analgesia Muscle relaxation Maintenance of homeostasis can all be achieved by administering one or more drugs

15. 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.

16. The potency of an inhalatory anesthetic MAC (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).

18. Intravenous anesthetics: Short acting: Barbiturates → metohexital thiopental, tiamital Imidazolic compounds → etomidate Alkylphenols → propofol Steroids → eltanolone Long acting: Ketamine Benzodiazepines → diazepam, midazolam

19. 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

20. PROPOFOL -very liposoluble fatty acid; -hepatic metabolisation in great extent → short effect; Pharmacodynamic action: -pharmacologic effects similar with those of Thiopental; -less residual effects.

21. KETAMINE Pharmacodynamic 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

23. 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.

25. 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.

27. Anesthesia apparatus

28. 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

29. -ventilation parameters setting module; -ventilation parameters and inhalation anesthetics monitoring module; -alarm module; -vacuum system (sucction).

31. Intraanesthesic monitoring

32. 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.

34. Preanesthetic visit

35. 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.

37. 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.

38. 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.

46. General anesthesia techniques • Balanced anesthesia; • Intravenous anesthesia; • Volatile anesthesia; • Combined techniques of general and regional anesthesia: • -general anesthesia + epidural anesthesia.

48. Regional anesthesia Subarachnoid (spinal) Epidural Sequential Caudal

49. 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.

50. 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.