วางยาสลบให สาเร จและปลอดภ ยใครว ายาก ผศ.น.สพ.ดร.ส ม ตร ด รงค พงษ ธร ภาคว ชาศ ลยศาสตร คณะส ตวแพทยศาสตร จ ฬาลงกรณ มหาว ทยาล ย

Transcription

1 วางยาสลบให สาเร จและปลอดภ ยใครว ายาก ผศ.น.สพ.ดร.ส ม ตร ด รงค พงษ ธร ภาคว ชาศ ลยศาสตร คณะส ตวแพทยศาสตร จ ฬาลงกรณ มหาว ทยาล ย

2 How Safe is "Safe"? Anesthesia Activities that are not 100% safe Stress and anxiety associated with strange environment Pain related to procedure Issue of patient safety: to survive the event without any negative consequences

3 INTRODUCTION General anesthesia: reversible unconsciousness adequate analgesia muscle relaxation Providing safe anesthesia requires Knowledge Technical skill Continuous awareness of the patient

4 Introduction One UK study undertaken in the midlate 1980 s The risk of anesthetic-related death ~ 1 in 870 in healthy dogs ~ 1 in 552 in healthy cats The risk worsened to ~ 1 in 30 if the dogs or cats were not healthy. Clarke KW, Hall LW (1990).J Vet Anaes 17, 4-10.

5 Introduction More recent studies have estimated the risk of anesthetic-related death in dogs and cats to nearer 1 in Dodman NH, Lamb LA (1992).JAAHA 28, Dyson DH, Maxie MG (1998). JAAHA 34,

6 Introduction The most recent and most extensive epidemiological study ~1 in 1880 in healthy dogs, (1 in 73) 1 in 895 in healthy cats (1 in 71) 1 in 137 in healthy rabbits (1 in14) Brodbelt DC (2006) The Confidential Enquiry into perioperative Small Animal Fatalities. PhD thesis. Royal Veterinary College. London university, London UK

7 Most anestheticrelated deaths occurred during induction or the early maintenance phase. The majority of deaths occur during the recovery period. Past Present

8 Causes of anesthetic related death A B C Unknown 39% cats, 28% dogs Cardiac arrest 17% cats, 33% dogs Ventilatory failure 17% cats, 13% dogs Circulatory failure 7% cats

9 Common procedures related to death Exploratory laparotomy (Dogs) Spay for pyometritis (Dogs) Dental surgery (Dogs & Cats) Spay (Cats) Diaphragmatic hernia repair (Cats) Treatment for urethral obstruction (Cats) Repair of jaw fractures (Cats)

10 Anesthetic mishaps Surveys of anesthetic deaths in human Hypoxia and anesthetic overdose (most common) Relative overdose (unstable patients) Absolute overdoses Cardiac arrests during induction of anesthesia Mechanical malfunction Human error

11 The anesthetist responsible for patient care Premedication until recovery NEVER to leave the patient unattended Continuous monitoring

12 ก อนการวางยาสลบ ส ขภาพ ห ตการ ประว ต ยาระง บความร ส ก สารน า อ ปกรณ วางยาสลบ ส ตวแพทย ประสบการณ

13 Fasting Healthy adult patient Food is withheld for 8-12 hours to minimize the risk of vomiting and regurgitation during anesthesia. Fluids only be withheld for 2 hours.

14 Fasting Pediatric animals (<4 months of age) Not fasted prior to surgery. If, the pediatric animal has not eaten in the last 3-4 hours, a small meal should be provided. To avoid complications associated with hypoglycemia.

15 ASA classification ASA 1 ส ตว ม ส ขภาพด ไม ม โรค หร อม โรคแต เก ดเฉพาะท ซ งไม ม ผลต อระบบการทางานของ ร างกาย ASA 2 ส ตว ท ม การเปล ยนแปลงหร อม พยาธ สภาพของร างกายน อย ซ งอาจม ผลเก ยวข องหร อไม เก ยวข องก บความผ ดปกต ท จะร บการผ าต ดร กษา ASA 3 ส ตว ท ม พยาธ สภาพของร างกายข นร นแรง ซ งอาจเก ยวข องหร อไม เก ยวข องก บความ ผ ดปกต ท จะร บการผ าต ดร กษาแต ม ผลต อการดาเน นช ว ตปกต ASA 4 ส ตว ท ม พยาธ สภาพร างกายข นร นแรงมากเป นอ ปสรรคต อการดารงช ว ตของส ตว ป วย ASA 5 ส ตว ท ม อาการเพ ยบหน ก แม จะได ร บการผ าต ดหร อไม ก ตาม ม โอกาสค อนข างน อยท จะม ช ว ตอย

16 Animal ID, BW Temperament Previous anesthetic experience History of previous illness Reason for admission Concurrent medications 16

17 Laboratory Data ASA Age 6 mth 6 mth-6 yr > 6 yr 1 and 2 PCV,TP, glucose PCV,TP,BUN PCV,TP,BUN, creatinine, urinalysis, ECG 3 CBC, urinalysis, glucose, BUN, creatinine CBC, urinalysis, surgery profile, ECG CBC, urinalysis, complete profile, ECG 4 and 5 CBC, urinalysis, complete profile, ECG CBC, urinalysis, complete profile, ECG CBC, urinalysis, complete profile, ECG Surgery profile: Glucose, BUN, creatinine, aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase Complete profile: surgery profile plus total protein, albumin, potassium, sodium, chloride, calcium. Phosphorus, total carbon dioxide, anion, total bilirubin, creatinine phosphokinase

18 PREANESTHETIC PERIOD Client communication Owner consent Anesthetic risk assessment Anesthetic plan Premedication Induction Maintenance Pain management 18

19 Surgical procedure Site of surgery and positioning May impair ventilation Limit access for monitoring Endanger adjacent nerves, blood vessels Potential for blood loss Duration of surgery Degree of pain Pain Inflammation

20 History Physical examination Anesthetic planning Laboratory examination Surgery procedure

21 PAIN PATHWAY

22 PAIN Stimulations VS Depth of Anesthesia

23 Mild Light Moderate Moderate Strong Deep

24 Pre-anesthetic Medication To calm or sedate an excited or vicious animal. To reduce the amount of general anesthetic required to induce anesthesia. To decrease pain and discomfort in the postoperative period.

25 Premedication Phenothiazine: Acepromazine Benzodiazepine: Diazepam, Midazolam Opioids: Morphine, Meperidine, Fentanyl, Tramadol Alpha 2 adrenergic agonist: Xylaxine Anticholinergic: Atropine

26

27

28 Premedication Contraindicated Recommended Atropine mg/kg ± geriatric tachycardic patient ± with opioids bradycardia patient healthy, elective Acepromazine mg/kg Meperidine 5 mg/kg convulsing patient, epileptic shock (hypovolemic) depressed patient hypothermic concern IV (histamine release) (excitement) healthy, elective geriatric (at lowest dose) Antiarrthymic geriatric brachycephalic mildly depressed mildly painful procedure

29 Premedication Contraindicated Recommended Morphine mg/kg GI obstruction history of opioid excitement elective moderate-good/mid-long duration analgesia vicious dog with ace Diazepam mg/kg previous bad experience (excitement) convulsing patient (IV) quick effect (IV) with ketamine when can t use ace Midazolam mg/kg Xylazine 0.5 mg/kg same as diazepam premedication (better choices exist) same as diazepam (IV or IM) good absorption IM only in healthy vicious patient

30 Animals Drugs Pre anesthetics Equipments IV catherization

31 31

32 32

33 33

34 Equipments 34

35

36 Anesthetic Machine: components Carrying Gases Anesthetic Agent Delivery System Breathing Circuit

37 Flowmeter

38 Vaporizer Precision vaporizer Non-precision vaporizer

39 Breathing system NON-REBREATHING REBREATHING cats and small dogs. Fresh gas flow: 200 ml/kg/min minimum flow 500 ml/min CO2 absorbent (soda lime) reservoir bag Fresh gas flow Partial Rebreathing: ml/kg/min

40 Rebreathing system

41 Non rebreathing system Ayre s T-piece Magill

42 Waste gas management

43 Induction Barbiturate: Thiopental Dissociative: Ketamine, Tiletamine-zolazepam Nonbarbiturate: Propofol, Etomedate, Alphalaxan Inhalation mask/chamber

44 Inhalation VS Injection Delivered by breathing in Delivered by injection

45 Injectable inducting agents Barbiturate Thiopental Non-barbiturate Propofol Etomidate Dissociative Ketamine/diazepm Tiletamine/zolazepam

46 Recovery from injectable Redistribution away from brain Thio, propofol, ketamine in dogs Metabolism Thio, propofol, pentobarbital Renal excretion Ketamine in cats (some redistribution occurs) Recovery from the anesthesia faster than whole body anesthetic elimination

47 Ketamine-diazepam induction

48 Intubation

49 49

50 Endotracheal intubation

51 Verify proper placement: Cough reflex Feel air passing through tube when animal breathes Visualize reservoir bag and unidirectional valves moving during respiration Palpate a single firm tube in throat Vocalization is impossible with tube correctly placed

52 Maintenance Injectable anesthetic bolus TIVA Inhalation anesthesia: Isoflurane, sevoflurane Balanced anesthesia

53 MAINTENANCE Monitor the patient closely vital signs remain within acceptable limits. Maintain the animal at an appropriate anesthetic depth. Patient monitoring The key to effective and safe anesthesia Warning of potential problems

54 Maintenance of anesthesia using injectable agents intermittent boluses Delayed onset of action Inability to maintain a constant plane of anesthesia Frequent changes in cardiopulmonary status Possibility of using more drugs constant rate infusion. Fewer sudden hemodynamic changes Less drug given More rapid recovery

55 Assisting ventilation All patients under anesthesia will hypoventilate and need some ventilatory support. If the patient's respiratory rate and character are within acceptable ranges, 'bagging' the animal a few times every 5 minutes is sufficient to prevent atalectesis.

56 C Circulation Oxygenation Monitoring Ventilation A B Record Personal

57 Patient Monitoring Vital signs are recorded to the surgery record every 5 minutes throughout the anesthetic procedure, but patient monitoring should be a continuous process.

58 Central Nervous System

59 Cardiovascular System

60 Electrocardiography

61 Blood pressure monitoring Absolutely essential for the safe conduct of anesthesia Blood pressure = intra-arterial pressure BP = TPR * CO {TPR = (MBP CVP) / CO} Tissue blood flow Systolic >80-90 mmhg to ensure adequate perfusion of vital organs

62 Oscillometric method

63 Doppler ultrasound

64 Respiratory System Clinical observation Respiratory rate Tidal volume Mucous membrane colour

65 Respiratory System

66

67 Hypothermia

68 Analgesia Premedication Maintenance Induction

69 Analgesia Local nerve block Regional anesthesia: Brachial plexus block, Epidural Intraoperative analgesia: Opioids, Ketamine, Lidocaine, Alpha 2 agonist Postoperative analgesia : Opioids, NSAID,

70

71 Inhibit Perception Anesthetics Inhibit central sensitization Local anesthetics Opioids NMDA antagonist (Ketamine) Inhibit Transmission Local anesthetics Inhibit peripheral sensitization Local anesthetics Opioids NSAIDs Corticosteroids

72 100% 80% 60% 40% 20% 0% mild premed Moderate premed Heavy premed

73 Anesthesia Injectable anesthesia Local/regional anesthesia Inhalation anesthesia

74 Inhalation Injectable Local/regional BALANCED ANESTHESIA

75 Drug Dose Species Route Duration Morphine mg/kg Ca IM SC 3-4 hours 0.5 mg/kg loading dose, followed by mg/kg/hour 0.1 mg/kg preservative free morphine Ca Ca Fe IM, slow IV IV Epidural Duration of CRI hours mg/kg Fe IM SC 3-4 hours 1-5 mg in 5-10 ml Ca Intraarticular

76 Drug Dose Species Route Duration Meperidine 3-5 mg/kg Ca/Fe IM SC 1-2 hours Fentanyl 5 µg/kg +3-6 µg/kg/hour 2-3 µg/kg +2-3 µg/kg/hour Ca Fe IV IV Duration of CRI

77 Local anesthetics Dose (mg/kg) Toxic dose (mg/kg) Time for onset (min) Duration (min) Lidocaine (dog), 6-10 (cat) Bupivacaine

78 Epidural anesthesia

79 Brachial plexus block

80 Interpleural Block Inject»»»»» into the thoracic cavity Thoracotomy or through a chest tube Bupivacaine: 2 mg/kg for dogs, 1 mg/kg for cats; follow-up doses at 6-hour intervals using half the initial dose. Lidocaine: 6 mg/kg for dogs; 3 mg/kg for cats; every 4 hours.

81 Infraorbital nerve block

82 Dental blocks

83 Premedication Tranquilizer Phenothiazine derivative Benzodiazepine Alpha 2 agonist Opioid Analgesic Anticholinergic Prophylaxis Antibiotic

84 Preanesthesia Anesthesia Recovery Duration of drugs actions

85 RECOVERY Continue Perioperative support and monitoring The anesthetist MUST stay with their patient until the endotracheal tube has been safely removed at least one TPR has been recorded and the patient is stable.

86 RECOVERY The anesthetist is responsible for informe any anesthetic or surgical complications any special needs Vital signs should be monitored in the recovering animal every minutes or as appropriate until the patient is sternal.

87 Pre-anesthesia Recovery of anesthesia

88 Any questions?