Drugs Anaesthetics PDF

Commonly used drugs in Anaesthesia NSCI 5711 – Introduction to Anaesthetic & Surgical Procedures  What is a premedication? Why do we use them? What are the names and classes of commonly used premedicants, and Lecture plan what a...

Commonly used drugs in Anaesthesia NSCI 5711 – Introduction to Anaesthetic & Surgical Procedures  What is a premedication? Why do we use them? What are the names and classes of commonly used premedicants, and Lecture plan what are their effects? Explain what induction is and what medications we use Discuss the use of medications in maintenance of general anaesthesia   Most medications have two names: 1. Generic/drug name – this is the drug's 'active ingredient’, the part of the medication that gives it it’s effect. 2. Brand/trade name - given by the pharmaceutical company (drug company) that manufactures the medication Generic names  Examples: vs. Trade  Generic/drug name: Buprenorphine names  Brand/trade name: Temgesic®  Generic/drug name: Meloxicam  Brand /trade name: Metacam®  Drug name (Brand name, manufacturer)  Meloxicam (Metacam, Boehringer Ingelheim) Pre-medications Who knows the name (generic or brand) of some premedications? Why do you think we give premedications?  Preanaestheic medication = “Premed”  The drugs administered prior to general anaesthesia.  Usually contains a sedative and analgesic, What is a +/- others depending on your patient Premedication?  Reasons for administering a premedication:  Sedation  Pre-emptive analgesia  Reduces the amount of other medications needed – synergy  To counter side effects of other medications  Sedation To calm and control the patient Reduce stress (animal & human!) Easier & safer to handle and restrain for Aims of a induction Premedication Reduces the “fight or flight” response Lower levels of catecholamines (adrenaline) and a reduced chance of triggering cardiac arrhythmia = smoother induction and recovery  Analgesia To smooth the recovery period after anaesthesia through continued mild sedation and pain relief Provided the duration of action of the premed is long enough Aims of a What can you do if the anaesthetic/surgery is longer than the duration of sedation? Premedication To provide or improve analgesia. Analgesia given prior to surgery may also reduce/or arrest the pain cascade. What would be signs that our patient isn’t sedated or analgesed on recovery? To reduce muscle tone - surgery  To reduce the total dose of the anaesthetic agents required for the GA (induction & maintenance) Lower doses reduce the risk of adverse side effects Especially important for inhalantional Aims of a anaesthetics Premedication To counter or reduce possible adverse side effects of a GA itself/other anaesthetic agents. Bradycardia - Atropine Nausea & vomiting – maropitant (Cerenia, Zoetis)  Unfortunately, there is no ideal premedication No single drug can do ALL of these things (sedation, analgesia, reduce side effects What is the etc) successfully alone ideal They all have the potential for adverse premedicant? effects  For the safe anaesthetic protocols including premedications should be tailored to fit each individual patient What is suitable for a 6-month old dog undergoing an ovariohysterectomy may not be the best choice for a 13 year old Premedication cat having a leg amputation or a protocols brachycephalic dog in respiratory distress  Classes of premedicants: Sedatives or sedative type medications Analgesics Commonly Anticholinergics used  A premed often uses a combination of premed Premedication drugs (one medication doesn’t do it all) Drugs  Drugs work in synergy: lower doses of each = less side effects  Not all premeds can be combined in the same syringe although they can be used together (separate syringes) – check with your veterinarian!  Three types of sedative agents Phenothiazines -Acetylpromazine α 2 Agonists - Medetomidine, Xylazine Benzodiazepines – Diazepam, Sedative – Midazolam type agents  Generic name: Acetylpromazine (may also be called acepromazine) Phenothiazines Brand names: Acezine 2, Acezine 10, ACP Effects: mild sedation   Generic name: Dexmedetomidine, Medetomidine, Xylazine  Brand name: Dexdomitor®, Domitor®, Medetomidine®, SedaMed®  Reversed with:  Generic/drug name: Atipamezole  Brand/trade name: Antisedan, Reversamed α-2 Agonists  Effects: mild-deep reversible sedation   Generic/drug name: Diazepam  Brand/trade name: (Pamlin®)  Generic/drug name: Midazolam (human medication and trade name is usually also Benzodiazepines midazolam) “benzos”  Reversal generic/drug name: Flumazenil (human medication and trade name is usually also flumazenil – usually will be kept in crash kit)  Effects: anxiolytics (reduce anxiety), can cause aggression   Opioids Analgesics  Non-steroidal Anti-inflammatory drugs (NSAID’s)  Names: Generic (brand name) Morphine Methadone Buprenorphine (Temgesic®) Butorphanol (Butorphic®, Torbugesic®) Pethidine Opioids Fentanyl Reversal generic/drug name: Naloxone (human medication and trade name is usually also naloxone – usually will be kept in crash kit) Effects: analgesia, mild sedation  NSAIDs – Non-steroidal anti-inflammatory drugs Sometimes used in premedications, but more often used as post-operative analgesia  Generic name: Carprofen NSAIDs  Brand names: Carprieve®, Rimadyl®, Carprofen®  Generic name: Meloxicam  Brand names: Metacam®, Loxicom®, Meloxicam® Effect: anti-inflammatory analgesia, anti-pyretic  Atropine  Historically was always used in premeds, but now more commonly only used as needed  Added to combat the expected bradycardia from the induction and general anesthesia Anticholinergics drugs.  Also combats secretions such as excess secretions Any questions? General Anaesthetic (GA)   General anaesthesia is a drug-induced unconsciousness that is characterized by controlled but reversible depression of the CNS and analgesia. In this state the patient is not arousable by noxious stimulation. Sensory, motor and autonomic reflex functions are What is the attenuated. (Lumb & Jones’ Veterinary Anaesthesia and purpose of a Analgesia) GA? Surgical anaesthesia is a state of GA that provides unconsciousness, muscle relaxation and analgesia sufficient for a painless surgery  Induction = the first part of the general anaesthetic and is the administration of an injectable anaesthetic agent that rapidly induces anaesthesia Many induction drugs can cause induction apnoea and therefore can cause an hypoxia. It is best Commonly practice to pre-oxygenate the patient for 5- 10 min used induction before induction agents Drugs used for the induction process are: Propofol (Repose®, Fresofol®) Alfaxalone (Alfaxan®) Ketamine Diazepam or Midazolam (usually used in combination with propofol, alfaxalone or ketamine) Inhalational anaesthetics (Isoflurane, Sevoflurane)   IV and gas anaesthetics should be given “to effect” during induction.  What does that mean?  The drug is given slowly until the desire effect Given “to is reached, and administration is stopped once effect” the patient is at a suitable depth of anaesthesia to allow endotracheal intubation. MAURO FERMARIELLO / SCIENCE PHOTO LIBRARY / Universal Images Group Rights Managed / For Education Use Only  Anaesthesia is maintained with inhalational anaesthetic gases: Isoflurane – most common Sevoflurane Halothane Maintenance Desflurane of anaesthesia Administered via a vapouriser The different types of inhalational anaesthetics need their specific vapouriser   MAC = minimum alveolar concentration  the concentration of inhaled anesthetic within the alveoli at which 50% of animals do not move in response to a surgical stimulus.  “dose” of gas anaesthetic  This is the number on the dial MAC  MAC of isoflurane is 1.3%  (Mouton Dowdy, 2019)  Constant rate infusions (CRI) of an induction agent, or a combination of these can be used to maintain or support Injectable the maintenance of inhalational maintenance anaesthesia of anaesthesia TIVA – total intravenous anaesthesia PIVA – partial intravenous anaesthesia  1. What class of drug is each medication eg. Methadone - opioid, meloxicam - NSAID, dexmedetomidine - α-2 agonist 2. The drug/generic name What do we 3. The trade/brand name want you to 4. When can this drug be used? – premed, know about induction, maintenance, post-op these drugs? 5. The desired effect of the drug – what effect are we using it for? 6. When referring to medications in assignments always “Generic name (Brand name, Manufacturer)”  Correct drug Correct volume Important! Correct patient When giving Correct time ANY drug, Correct route always check: Always have an assistant to restrain for administration. Any questions?