L4 Anaesthestic risk and pre-anaesthetic assessment.pptx

+ Anaesthetic risk and preanaesthetic assessment Dr Luiz Santos BVMS DACVAA Module 14 – Supporting the Patient + ILOs Year ILO - CP3030 Apply knowledge of epidemiological studies to assess anaesthetic risk in veterinary patients and identify strategies to minimise risk. Describe Describe the A...

+ Anaesthetic risk and preanaesthetic assessment Dr Luiz Santos BVMS DACVAA Module 14 – Supporting the Patient + ILOs Year ILO - CP3030 Apply knowledge of epidemiological studies to assess anaesthetic risk in veterinary patients and identify strategies to minimise risk. Describe Describe the ASA physical status classification system and assess which ASA category a patient should be attributed to Identify Identify groups of patients at increased risk of anaesthetic mortality/morbidity based on signalment Identify Identify some of the factors that can affect patient safety during anaesthesia Explain Explain the rationale for pre-anaesthetic blood testing and be able to identify those patients where it is recommended Recognize Recognize major disease categories which increase anaesthetic risk and explain how these risks could be reduced + Risk of Death Healthy Unhealthy Dogs 0.05% 1.3% Cats 0.1% 1.4% + Other Species  Horses  Healthy ~1%   Colics 11% Rabbits  Healthy 0.7%  Sick 7% + Points to note from Mortality Studies Common Causes of Death • Small Animals – Cardio-respiratory causes • Equine – Post-anaesthetic injuries Timing of Death • Majority occur post-operatively!! • Possibly due to withdrawal of monitoring and support in recovery phase + Grade Description Example 1 Healthy Patient Spay 2 Mild, fully compensated, systemic disease Mild heart disease, controlled diabetes 3 Severe systemic disease functionally affecting patient Uncontrolled diabetes, anaemia 4 Severe systemic disease which is a constant threat to life Shock, uncontrolled heart failure 5 Moribund patient, Shock, severe not expected to trauma survive >24hrs with or without treatment ASA Grade Addition of E (e.g. 4E) designates an emergency) + Anaesthetic Risk Signalment Disease + Signalment - Age  Older animals have reduced physiological reserves  Greater cardiorespiratory impact of anaesthesia  More prone to hypothermia etc.  May have concurrent disease  Very young animals (<12 weeks in dogs & cats) are physiologically immature + Breed  Brachycephalic at increased risk  Small, collapsible airways that are prone to obstruction and severe respiratory impairment.  Some breeds have unexpected responses to drugs  Greyhounds, Herding + Body Weight/Condition  Cardio-respiratory  PK of drugs  Wound healing  Ventilation complications + Anaesthetic Risk Signalment Procedure Disease + Patient Safety + Types of errors 20x left closed 5x intra-arterial drug administration 16x unrecognized oesophageal intubation 20x medication errors + Outcome  ‘Nurse   confirmed intubation’ Different color for bandages covering arterial catheters Standard Operation Procedures (SOPs) • • • Drug name Patient name Route Read out loud prior to IV administration + Results – Reduction!  75% pop-off valves closed  75% unrecognized oesophageal intubation  60% in accidental intra-arterial injection  50% medication error + + Risk Summary findings  ASA grade  Procedural urgency  Major procedures  Duration of procedure  Increasing age  Extremes of weight  Fluid therapy (cats only)  Endotracheal intubation (cats only)  Mask inductions + Pre-Anaesthetic Assessment Aims to identify disorders which may affect anaesthetic risk Assessment should involve thorough And may involve other diagnostic tests Primarily looking for evidence of significant functional impairment of bodily systems Clinical examination – Focused on function & looking carefully for expected abnormalities E.g. Blood testing, radiography, ultrasonography, echocardiography, ECG These problems may then be stabilised History May result in changes in anaesthetic techniques May result in cancellation/change in procedure + Blood Tests – Sick Patients  Useful to establish disease presence, severity & monitor for response  Particularly useful to the anaesthetist are measurements of organ/system function  E.g. glucose trend, potassium level trend  In older patients might be recommended more often to check trends + Pre-Anaesthetic Testing What we do in the SAH  Elective ASA 1 dogs for elective surgery (<7 years)  Provided normal history and clinical exam – no blood sample  > 7 years old, >ASA 1 or emergency cases – Pre-anaesthetic blood test.  Pre-anaesthetic testing doesn’t always entail a ‘full’ profile of bloods.  Pick what’s relevant to the patient’s disease process  Our minimum is PCV/Total protein, Urea/Creatinine, Electrolytes, Glucose. + Major Disease Factors Influencing Risk  May be many and varied! Anaesthetic considerations may be based on any of the major body systems. A small number of examples are given here   Cardio-vascular Respiratory  Haemopoietic  Endocrine  Gastrointestinal  Renal  Neurological  Coagulation Delivery of Oxygen depends on • Cardiac output • Blood oxygen content • Oxygen saturation • Haemoglobin concentration + Animals may present with a wide variety of underlying injuries.  Fractures/Dislocations  Wounds  Haemorrhage  Thoraco-abdominal trauma  Organ rupture  Haemoabdomen  Uroabdomen  Head Trauma + Logical step + Pre-Anaesthetic Assessment Promotes a logical approach to anaesthetic choices using: Consideration – Animal has renal disease Aim – Maintain blood pressure under anaesthesia so renal perfusion remains adequate Plan – Administer fluid therapy etc… Anticipated complications… +