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Anaesthesia protocol development: Insights from National societies regarding new antiplatelets, new...
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Transcript of Anaesthesia protocol development: Insights from National societies regarding new antiplatelets, new...
Anaesthesia protocol development: Insights from National societies
regarding new antiplatelets, new anticoagulants and haemostatic
agentsG Ogweno
Dept Of Medical PhysiologyKenyatta University
Factors contributing to protocol based healthcare
• Cost pressures• Technological advances• Increase in management-led decision making• Consumer awareness• Value for money movement• Availability of information• Non-clinicians with the authority to question
effectiveness• International consensus• Professional accountability• Changing demographic profile
Why protocols in anaesthesia?
• To ‘standadize’ medical care, increase quality , effectiveness, specificity, sensitivity, resoluteness and patient outcomes=clinical pathways
• ‘Experts’ best faith efforts to offer reasonable pathways for patient management
• To enhance best evidence based practice
What are protocols?
• Special set of rules defining relationship=communication
• Based on current evidence• Identify most important questions related to
clinical practice, possible options and outcomes=decision points and course of action
• Identify, summarise, evaluate highest quality evidence, risk vs benefit and cost effectiveness
Forms of protocols
• Summarized consensus statements on best practice
• Guidelines: diagnosis, treatment by national associations
• Clinical pathways• Trials: clinical, research
Levels of Evidence
Hierachies of evidence• Clinical trials I-well designed randomised controlled trials II-1a: well –designed controlled trials with pseudo-
randomisation II-1b: well-designed controlled trials with no
randomisation• Cohort studies II-2a: well designed cohort (prospective) with
concurrent controls II-2b: well designed cohort(prospective) with
historical controls II-2c: well designed cohort (retrospective) with
concurrent controls II-3: well designed case –controlled (retrospective) III- large differences from comparisons between
times and/or places with or without intervention Iv-opinions of respected authorities based on
clinical experience, descriptive studies and reports from expert committees
Forms of evidence
Classes of recommendations and levels of evidence
• Classes of recommendations Class I Evidence and/or general agreement that a given treatment or procedure is
beneficial Class II Conflicting evidence and/or divergence of opinion about the
usefulness/efficacy of the treatment or procedure Class IIa Weight of evidence/opinion in favour of usefulness/efficacy Class IIb Usefulness/efficacy is less well established by evidence/opinion Class III Evidence or general agreement that the treatment or procedure is not
useful or effective and in some cases may be harmful• Level of evidence Level A Data derived from multiple randomised clinical trials or meta-analyses Level B Data derived from a single randomised clinical trial or large non-
randomised studies Level C Consensus of opinion of the experts and/or small studies, retrospective
studies, registries
Perioperative Anticoagulation
Indications • Patients on Anticoagulation undergoing
surgery Pitfalls • Over Anticoagulation or premature use results
in significantly increased bleeding complications
• Bleeding complications result in transfusions and stopping Anticoagulation which risks clots
Laboratory testing
Common• Blood counts, including
platelets• Routine Kinetic: PT,aPTT,
TT, ACT, INR• Bleeding time• Not predictive of bleeding
Research• Kinetic: ECT• Factor assays: anti-Xa• Capacitative:
Thrombelastography, Thrombogram
• Platelets: optical aggregometry, plateletworks,multiplate
• Promising though not readily available
Perioperative anticoagulation Protocols: sources of information
• Analysis of published studies with LMWHs and the type of anaesthesia is reported
• Case reports in the literature• Calculations from cases reported to
manufacturers• Questionnaires to anaesthesiology societies
Risk stratification
Bleeding• High risk procedures:
– Neurosurgery– Abdominal or pelvic procedures– Orthopedic joint procedures– Major ENT or oral surgery– Endoscopy with biopsy– Epidural Anesthesia – Prolonged general anesthesia with
intubation• Very Low Risk Procedures:– Procedures
• Dental procedures• Cataract Surgery• Dermatologic procedures• Pacemaker and IACD placement• Endoscopy without biopsy
Thromboembolism• High:
• Deep Vein Thrombosis within last 3 months• Pulmonary Embolism within last 3 months• Cardiac thromboembolism (any cause) within 1 month• Recurrent Venous Thromboembolism• Strong Thrombophilia
– Active cancer– Antiphospholipid Antibody Syndrome
(uncommon)– Antithrombin III deficiency (rare)– Protein C Deficiency – Protein S Deficiency
• Mechanical heart valves– Mitral valve replacement– Ball-Cage or other older cardiac valve– Higher risks
» Comorbidity (e.g. Congestive Heart Failure)
» Atrial Fibrillation with mechanical valve• Intermediate:
• Atrial Fibrillation with CHADS-2 Score 4 or higher• Very Low Risk:
• No DVT for 3 months• Chronic Atrial Fibrillation without stroke• New bileaflet aortic valves (St. Jude or Medtronic)
Central neural blockade (CNB) in anticoagulated patients: Risks
• Symptomatic spinal/epidural haematoma• greatest risk appears effective during insertion or
removal of spinal or epidural needles or catheters
• SSEH do NOT necessarily progress to permanent neurological damage
• Risk of SSEH appears higher for epidural than spinal-especially traumatic or difficult access
• Not all vascular traumatic damage recognizable
LMWH and spinal Haematoma In US
• Enoxaparin introduced US in 1992=dose 30mg bd• More than 40 cases of spinal haematomas for 1st
5 years of use• 1997: FDA issued warning, manufacturers to
adjust insert• ASRA tasked to provide guidelines• Horlocker et al analysed case reports/ series of
complications introduction of enoxaparin• ASRA consesus conferences in 1998, 2002, 2007
and 2007
Highlights of US Guidelines• Anticoagulation is not an absolute
contraindication for regional anesthesia• Regional anesthesia may be safely performed
provided risk stratification is done• No added risk at prophylactic doses• Complications may be independent of drug
action: patient related, procedure specific• Cases to be judged on individual basis and
exercise caution= continous vigilance• Recognizes data insufficiency
European perspectives
• LMWH-enoxaparin many years experience@40mg od
• Moen et al 2004 review of severe neurological complications between 1990-1999
1,260, 000 spinal blocks450, 000 epidurals including 200,000 labor
epidurals
Results of Moen et al
Findings• 127 complications Spinal haematomas=33 Cauda equina syndrome=32 Meningitis=29 Epidural abscess=13 Miscellanous=20• Permanent neurological
damage in 85 patients
Severe neurological complications
• 1: 20-30,000 in all groups• 1:25,000 after obstetric
epidurals• 1:3,600 in all others• Rates less in obstetrics• Epidurals higher than spinal• Osteoporosis risk factor
Haemostatic agents
• Whole blood and plasma products as haemostatic agents limited efficacy and associated with complications
• Available systemic alternatives:Fibrinogen concentrateProthrombin complex concentrate (PCC)Recombinant factor vii
Recombinant factor vii
• Efficacy demonstrated in haemophilia-level 1a• Trials ongoing in trauma= level iii• Case reports of post administration
thrombophilia• Most guidelines indicated only in bleeding
haemophilia• Other uses experimental=must warn of grave
consequences
European perspectives on haemostatic agents
• Efforts to eradicate use of FFP• Use of capacitative tests strongly
recommended, if available• Strong recommendation on identification and
replacement of individual factors• Austrian OGARI: use of fibrinogen and PCC as
opposed to FFP in trauma
Anesthetic management of patients receiving antiplatelet medications
• Exert diverse effects on platelet function• Impossible to extrapolate between groups• No wholly accepted test to guide therapy• Appear to represent no added risk for CNB
complications-actual risk unknown• Bleeding risk may be increased by concurrent use
of other antithrombotic medications• Cyclooxygenase-2 inhibitors minimal effect on
platelets, could be considered as alternatives
Limitations of Guidelines
• Desired level of evidence does not exist• Subject to major flaws• Failure to account for multiple comorbidities• Tend to produce an average result• Unintended consequences• Poorly understood factors• Too complicated• Misuse of guidelines
Conclusions
• Perioperative management of haemostatic agents pose significant challenge
• Guidelines may help minimize risks• Risks vs benefit should be carefully weighed in
any protocol development• Good protocols should be simple to follow
and based on facts• Unfortunately, NO such data exist for
perioperative antithrombotic agents