GENERAL ANAESTHESIA Katarina Zadrazilova FN Brno, Nov 2010 ..aims •What do anaesthetists do •Basic anaesthetic management •Drugs, gases, monitoring, machines The role of anaesthetist •Ensures safe anaesthesia for surgery •Is responsible for patient safety in theatre •Ensures the anaesthetic machine and drugs are checked and correct •Liase with the surgeon and scrub team – ensure that the operation can proceed smoothly •Keep an anaesthetic record •Makes a postoperative plan Anaesthetic plan •Preoperative •Intraoperative •And postoperative management Anaesthetic plan •Preoperative •Intraoperative •And postoperative management Preoperative management •Anaesthetic assessment :history and examination •Relevant investigations : lab, CXR, ECG •Optimise chronic condition •Plan for intra and post op pain refief •Discuss ev. HDU/ICU post op bed for patient •Consent the patient •Prescribe premedication • Anaesthetic assessment •Previous surgery (GA, LA, complications) •Medical hx, Medication, FH •Allergies •Last meal, drink ! •Teeth •Pregnancy •Examination: airway assessment, neck, back + general physical exam. • Risk assessment – ASA grade •I Healthy patient •II Mild systemic disease, no functional limitations •III Severe systemic disease- definite functional limitation •IV Severe systemic disease that is a constant threat to life •V Moribund patient not expected to survive 24 hours with or without operation Premedication •Sedation/anxiolysis (Benzodiazepines) •Analgesia only if pain (opioids) •Reduce airway secretions + heart rate control + hemodynamic stability •Prevent bronchospasm •Prevent and/or minimize the impact of aspiration •Decrease post-op nausea/vomiting Consent •Discuss all options GA/regional •Risks versus benefits •Complications – common, rare and serious •Make pain relief plan Complications ▫NO RISK = NO ANAESTHESIA ▫ •Common (someone in a street) ▫PONV, sore throat, backache, headache, dizziness • •Rare and serious (someone in a big town) ▫Damage to the eyes, anaphylactic shock, death, equipment failure Mortality of anaesthesia (ASA I) •Risk of death or brain damage ▫1: 100 000 – 200 000 • •Dying in a plane crash ▫1 : 200 000 •Dying in a car crash ▫1 : 5000 Anaesthetic plan •Preoperative •Intraoperative •And postoperative management Teamwork ! anaesthetist ODP surgeon scrub nurse Operating theatre Figure 1. Operating room layout showing how space can be controlled by positioning the anesthesia personnel (A), machine (M), and drug cart (D). The infusion (I) is in view and a visitor (V) can be provided with a good view while remaining outside the "controlled space." Operating theatre •Allow surgery, ECT • •Allow diagnostic method (CT, MRI) History •Opium (Egypt, Syria) ▫Hippokrates 400 BC ease pain •1555 Andreas Vesalius - arteficial ventilation through tube between vocal cords, ventricular fibrilation (animals) •Valerius Cordus (1546) ether •1773 N2O Joseph Priestley (1733-1804) • morton Beginning of GA •October 16th 1846 ether general anaesthesia Boston dentist William Thomas Green Morton to Gilbert Abbott (tumor of mandibule) •February 6th 1847 Prague - first czech ether anaesthesia - Celestýn Opitz •1895 direct laryngoscopy Alfred Kirstein in Berlin. AIMS OF ANAESTHESIA Triad of anaesthesia •Neuromuscular blocking agents for muscle relaxation •Analgesics/regional anaesthesia for analgesia •Anaesthetic agents to produce unconsciousness Stages of anaesthetics •Induction – putting asleep •Maintenance – keeping the patient asleep •Reversal – waking up the patient • • Intravenous anaesthetics •Onset of anaesthesia within one arm – brain circulation time – 30 sec •Effect site brain ▫Propofol ▫Thiopentale ▫Etomidate Anaesthetic gases •Isoflurane •Sevoflurane • •Halothane •Enflurane •Desflurane • •N2O – nitrous oxide Inhalational anaesthetics Anaesthetic gases •Used for maintainance, sometimes induction • •Anaesthetic ‘gases’ are administered via ▫ vaporizers • Inhalational anaesthetics Induction + maintenance Intravenous anaesthetics Muscle relaxants - NMBs •Tracheal intubation •Surgery where muscle relaxation is essential •Mechanical ventilation • •Place of effect - neuromuscular junction •History - South American Indians (kurare) • Neuromuscular blocking agents Analgesics •Simple : paracetamol, NSAID •Opioids : morhine, fentanyl ▫Via opioid receptors MORPHEUS- GREAK GOD OF DREAMS Monitoring •Basic: ▫NIBP, ECG, Sat, ETCO2, FiO2 • •Extended: ▫Nerve stimulator, temperature, diuresis, IBP, CO, CVP, perioperative acid-base, lab Standard monitoring ECG Non-invasive Blood Pressure Invasive Pressure Monitoring Gas Analysis Pulse Oximetry: Peripheral Nerve Stimulation: •Mix gases, ventilate, preserve heat and moisture •High pressure • central gas supply/ cylinder •Low pressure system •Flowmeters •Vaporisers •Breathing circuit: ▫bag + tubes ▫valves (uni directional) ▫CO2 absorber •Ventilator Anaesthetic machine Anaesthetic machine Airway management •Indication for intubation: •Need of relaxation or PPV •Full stomach • •Orotracheal intubation, nasotracheal intubation with direct laryngoscopy •Tracheotomy •Laryngeal mask •Cricothyreotomy INTUBATION - Always consider why you are exposing the patient to the risk, albeit small, of intubation- a.) protection from gastric aspiration and secretions b.)access and maintenance-in difficult airway and difficult surgical positions/procedures c.) provide positive pressure ventilation- can be done for shorter periods with a mask or LMA d.) oxygenation- to provide a controlled concentration of oxygen up to 100%, also provides for complete scavenging e.) secretions- facilitates removal of secretions via suctioning Intubation Laryngeal Mask Anaesthetic plan •Preoperative •Intraoperative •And postoperative management Postoperative care •ICU/HDU or ward •Monitoring according to type of surgery and patient’s condition •Post-operative pain control •Lab check up •Infusion therapy, blood loss monitoring Questions ? ana_1_075_anaphylaxis_13_01_med