Perioperative risk Flashcards
Metabolic response to injury
Ebb and flow
24-48 hours ebb
Response to tissue injury
Reflex activity and inhibition of central thermoregulation are fight or flight
Plasma glucose increases in proportion to severity of injury
Lipolysis is increased but fatty acid re-esterification may be stimulated by raised plasma lactate level (impaired perfusion of fat deposits)
Flow Increased BMR Muscle catabolism and resistance to anabolic effects of insulin ATP by glycolysis Glucose from lactate Increase in nitrogen and creatinine Proteolysis
Glutamine important fuel for immune system and precursor for glutathione - NO metabolism (gut mucosal barrier)
Insulin resistance after injury
Mediators of injury
Counter regualtory
Glycogen breakdown
Suppression of insulin release
Increased sympathetic nervous
Lipolysis
Protein metabolism Increased hepatic synthesis by IL6 Increased microvascular permeability Raised plasma concentration of fibrinogen and CRP Fall in albumin
Proinflamattory cytokines
Mimic some responses
IL6 induction of prostanoids at BBB
Activation of HPA axis
Peri-operative medicine
Surgical factors
Patient factors
Systemic factors
Pre-existing comorbidity: CV Respiratory Anaemia DM CKD Obesity Immunocompromised CLD
Elderly have less physiological reserve
Obesity associated with lots of conditions and can also result in chronic inflammatory response driven by excess adipose tissue
Also increased insulin resistance
OSA
STOP BANG
5 or more means OSA
Men, older, diabetes, HTN, snoring, large collar size are risk factors
Risk assessment
ASA 1 0.05 2 0.4 3 4.5 4 25 5 50
PAC
CPET trusting
Assessment
Anaerobic threshold of at least 11mL/kg/min is considered necessary
OPTIMISE
ASSESS PHYSIOLOGICAL RESERVE
ERAS
Preoperative phase
Operative phase - minimally invasive, minimising drains etc.
Post op phase Daily goals
