Anaesthesia Monitoring - Part 1: The Patient PDF

Anaesthesia Monitoring Part 1: The Patient Monitoring How do YOU define monitoring? “to observe and check the progress or quality of (something) over a period of time; keep under systematic review.” “maintain regular surveillance over” “….report on.” Who has assisted with m...

Anaesthesia Monitoring Part 1: The Patient Monitoring How do YOU define monitoring? “to observe and check the progress or quality of (something) over a period of time; keep under systematic review.” “maintain regular surveillance over” “….report on.” Who has assisted with monitoring a general anaesthetic before? Who finds it easy?  The Veterinary Nurses Role A trained veterinary nurse should be able to: Understand the effect of anaesthesia on the body Know normal parameters (HR, RR, temp etc.) Watch the patient constantly Use and interpret readings from specialised monitoring equipment Record information/parameters every 5 minutes Communicate with the rest of the veterinary team Respond to changes in anaesthetic depth with the veterinarian’s guidance *next year!* Troubleshoot abnormalities *next year!* Looking after the most important monitoring machine – you! Look after yourself – eat and drink beforehand, take breaks if needed Be on form – don’t be hungover, under the influence etc. If you are unwell, pass on the monitoring to another person – possibly the difference between an animal’s life and death. Utilize monitoring equipment, but don’t rely on it. Communicate with your team Make sure not to become complacent! WHY do we Monitor? WHAT do we monitor? Listen to the heart rate and rhythm Watch and count respiration Look at the mucous membrane (MM) colour Blanch the MM and look at capillary refill time Test and palpate the jaw/muscle tone Look at the eye position Monitor temperature Organ Systems Respiration rate Respiration pattern  Respiratory system MM colour Heart rate and pulse rate Heart/pulse character  Cardiovascular system MM colour CRT  Neuromuscular system Reflexes = pedal, palpebral Muscle tone = jaw tone  Thermoregulatory Temperature Respiratory System Respiratory rate (RR) Respiratory effort/character Tidal volume Respiratory Rate Number of breaths per minute (brpm) How do we count this? Over 15 seconds, then multiply by 4 Count the movement of the reservoir bag, ET tube condensation and/or chest rise and fall Anaesthetized patients have a decreased RR – because of drugs used!  Species Normal RR Anaesthetic RR Cat 20-30 brpm 10-20 brpm Dog 10-30 brpm 8-20 brpm Pocket Pets 60-70+ brpm 20-100 brpm *Depends heavily on individual stress, excitement, physiology, body composition, environment etc. Respiratory Effort Look at pattern and character Not always smooth in anaesthetized patients Lighter the patient more forceful the respiration Laboured breathing – what can this be a sign of? Drug induced i.e. cats can hold breath on inspiration after Ketamine or Propofol Respiratory Tidal Volume The air taken into the lungs in ONE normal breath 10-15mL/kg in most species Assess chest rise/fall or check the reservoir bag *We need the tidal volume and weight, to work out the reservoir bag size* Mucous Membrane colour (MM)  Mucous Membrane colour (MM) Colour Possible Reason Pink Normal Blue/purple Cyanosis, hypoxia = not enough oxygen getting to the tissues Yellow Icteric = may indicate liver disease Pale pink or white Hypotension, hypothermia, bleeding, anaesthesia too deep, anaemia, drugs Dark pink/brick red Hypercapnia = high blood CO2 Cardiovascular System Heart rate (HR) Pulse rate (PR) Heart rhythm Heart Rate How do we measure heart rate? Manually palpate chest Stethoscope use to listen to the chest Sometimes you can see the heart beating! Also known as ‘auscultation’ Tachycardia Heart beating too fast Bradycardia Heart beating too slow Pulse Rate  Species Normal HR Anaes HR Cat 160-200 bpm 100-170 bpm Dog 70-140 bpm 60-140 bpm Pocket pets >250bpm Diff. to count *Depends heavily on individual stress, excitement, physiology, body composition, environment etc. *The pulse rate should be the same as the heart rate and can give you some idea about cardiac output and circulation adequacy* Why too fast or why too slow? Tachycardia (fast) Bradycardia (slow) Drugs Drugs Not deep enough Too deep Not enough analgesia Hypothermia Hypercapnia Hypertension Hypoxaemia Vagal stimulation – eye surgery Hypotension Acidosis (severe) Other disease processes Hypoxia Arrhythmias Hypoglycaemic Heart Rhythm and Character Is the rhythm regular or irregular? Is the character strong or weak? Listen to as many hearts as you can! Any irregularity with heart rates or sounds should be immediately communicated to the veterinarian.  Capillary Refill Time (CRT) Where & how would we take a CRT? Quick refill = good perfusion Slow refill = not so good! Remember to LOOK! Lift the lip on your patient & check the colour and the refill time in one go Neuromuscular System Reflexes Muscular tone  Reflexes Palpebral (Eye blink) As anaesthesia deepens this reflex is lost around Stage 3 plane 2 Pedal (Toe pinch) Lost earlier than palpebral Pupillary light Depends on drugs used Tap the medial canthus of the eye area Muscle Tone Measure scale 1-5 1 = awake/tight 5 =very loose, no resistance Muscle tone will become looser as the level of anaesthesia deepens Jaw tone is measured by stabilizing top jaw (maxilla) with index finger and pulling bottom jaw (mandible) always using your thumb! Thermoregulatory Core body temperature Temperature Important to check as anaesthesia influences thermoregulation. decreases metabolic heat production increases heat loss gases are cold Digital thermometer easier to use and often goes to a lower temperature than mercury Normal Body Temperatures Species Normal Temp Cat ~38-39 Dog ~38-39 *Depends heavily on individual stress, excitement, physiology, body composition, environment etc. Monitoring the Patient Key times to monitor? Pre-medication Level of sedation: Airway obstruction possible if highly sedated? Monitoring body temp: To help prevent hypothermia before surgery More invasive monitoring may include: Pulse Ox, BP, ECG, O2 therapy Induction and Intubation High risk stage Is animal breathing? Is animals heart beating? Stage of anaesthesia? Maintenace Anaesthesia Check the ‘Stages of Anaesthesia’ to assess anaesthetic depth Use of machines AND the veterinary nurse Monitoring constantly, recording every 5 mins How to we assess anaesthetic depth? A Doctor named Arthur Guedel classified anaesthetic depth into 4 major stages, these are used today to monitor our patients. They help identify the changes in the level of unconsciousness, from “near awake” to “near death”.  Stage 1 = Voluntary Excitement Stage 2 = Involuntary Excitement Stage 3 = Surgical Anaesthesia Planes in this stage: Light Anaesthetic Depth Medium Deep Very Deep (Discussed below in detail) Stage 4 = Bulbar Paralysis Should pass quickly between stage 1 and 2 Anaesthetic Depth – Loss of functions 1. Pain & Memory 2. Consciousness 3. Motor co-ordination 4. Response to external stimuli 5. Muscle Tone 6. Protective Reflexes (e.g. gag) 7. Autonomic function (i.e. normal control of sympathetic & parasympathetic nervous systems) 8. Normal control of heart & lung function result = dysfunction 9. Control of Ventilation result = respiratory arrest 10.Control of Heart/cardiovascular function = cardiac arrest Recovery Highest risk stage Often gets poorly observed Extubation takes place Warmth/quiet Ventilation Assess MM colour/pulse ox, use BP monitor Respiratory rate and effort Anaesthesia Monitoring Tips Always check the machine before EVERY patient Make sure you have an emergency kit and other people close If using machines and they beep – CHECK YOUR PATIENT FIRST – then check the machines. Try to see the WHOLE picture, rather than just one parameter Communication is key Aim is to keep the patient as light as APPROPRIATE for the procedure Stability is the goal Monitoring Sheets Why do we bother recording? Monitoring Sheets The use of forms, especially a GA form to collect your data, is GOLD STANDARD. You should be monitoring constantly and recording the information in 5 min intervals. Make a form of your own if that helps, it should be tailor made for each clinic What is a Monitoring Sheet Visual representation of anaesthesia from induction until recovery Template is used & filled out for each individual patient MAKE one that suits your needs if you don’t have one GOLD STANDARD = 5min interval recording, monitoring constantly Best presented in a graphical format & is the ONLY way to see GA trend Legal medical record – need to be an accurate representation of what happened, and should be kept with other patient documents What information do we need? Date IV Catheter site placement Patient Name & # Fluid therapy – hrly rate, type, Species, breed, age, sex, BW amount delivered Any history of previous events (A) circuit used and check Clinical Exam findings and concerns Endo-tracheal tube size ASA classification Inhalational agent used Pre-med drugs given – Time, amount, Other comments area route, effect