Anaesthesia - Lectures Flashcards
What are the pros and cons of:
- Vitamin K antagonists (Warfarin)
- DOACS - Direct thrombin inhibitor (dabigitran) & Factor Xa inhibitors (rivaroxaban, apixaban, edoxaban)
in the context of surgery?
- For those taking a vitamin K antagonist (e.g., warfarin), it takes several days until the anticoagulant effect is reduced and then re-established perioperatively; the risks and benefits of “bridging” with a shorter acting agent, such as heparin, during this time are unclear.
- The newer direct oral anticoagulants (e.g., direct thrombin inhibitor dabigatran, factor Xa inhibitors rivaroxaban, apixaban, edoxaban) have shorter half-lives, making them easier to discontinue and resume rapidly, but the direct factor Xa inhibitors lack a specific antidote, which raises concerns about treatment of bleeding and management of patients who require an urgent procedure.
What is the general approach to the Perioperative management of patients receiving anticoagulants? (4)
- How is thromboembolic risk for patients with AF determined?
- How is thromboembolic risk for patients with recent stroke/PE determined?
- What is the main factor determining bleeding risk?
- Which patients likely require bridging? What agents might you use?
Outline a perioperative thrombotic risk.
- High? (8)
- Intermediate? (6)
- Low? (4)
Case - A 76 year old female with non-valvular AF, HTN, and prior stroke 6 months ago, receiving warfarin, requires elective hip replacement with neuraxial anaesthesia; renal function is normal, and weight is 75 kg. This patient has a very high thromboembolic risk (table 1) and a low bleeding risk (table 3).
- What is your approach to her perioperative management of anticoagulation? (5)
- Stop warfarin five days before the procedure (last dose on preoperative day minus 6).
- Preoperative bridging with dose LMW heparin (e.g., enoxaparin 80mg subcutaneously twice daily) starting on preoperative day minus 3, with last dose on the morning of day minus 1.
- Resume warfarin within 24 hours after surgery (usual dose).
- Postoperative low dose LMW heparin for VTE prevention (e.g., enoxaparin 40mg subcutaneously once daily) within 24 hours after surgery until postoperative bridging is started.
- Postoperative bridging on post-op day 2 or 3, when haemostasis is secured (e.g., enoxaparin 80mg subcutaneously twice daily; continue for at least four to five days, until the INR is therapeutic.
Case - A 70 year old male with non-valvular AF, diabetes, and HTN (CHA2DS2-VASc score = 3) receiving dabigatran who requires a colon resection for cancer; renal function is normal. This patient has an intermediate thrombotic risk and a high bleeding risk.
- What is your approach to his perioperative management of anticoagulation? (5)
- Stop dabigatran three days before the procedure (off dabigatran for two days before the procedure and the day of the procedure).
- No bridging.
- Resume dabigatran on day +2 or +3 after surgery, when patient is able to take medication by mouth.
- Use prophylactic dose low molecular weight (LMW) heparin for VTE prophylaxis for the first 2-3 post-op days.
Case - A 55 year old male with an unprovoked DVT 4 months ago, receiving apixaban 5mg twice
daily, who requires a colonoscopy because of a personal history of premalignant colorectal polyps; renal function is normal. This patient has a high thrombotic risk and a low bleeding risk.
- What is your approach to his perioperative management of anticoagulation? (5)
- Stop apixaban 2 days before the procedure (off apixaban for one day before the procedure and the day of the procedure).
- No bridging required.
- Resume apixaban the day after the procedure, after at least 24 hours have elapsed when haemostasis secured.
Case - A 68 year old female with non-valvular AF, HTN, and congestive heart failure (CHA2DS2-VASc score = 4), receiving rivaroxaban 15 mg daily in the morning, requires a dental cleaning and two dental extractions; CrCl is 35 mL/min. This patient has a high thrombotic risk and a low bleeding risk.
- What is your approach to his perioperative management of anticoagulation? (5)
- Do not take rivaroxaban on the day of the procedure.
- Use oral tranexamic acid mouthwash just before the procedure and 2-3 times that day after the procedure.
- Resume rivaroxaban the day after the procedure, after at least 24 hours have elapsed (assuming the dental extractions were uneventful).
When should you resume anticoagulants after surgery if there is a high risk of bleeding?
When should you resume anticoagulants after surgery if there is a low risk of bleeding?
- Resume anticoagulants 48 to 72 hours after surgery if high risk of bleeding.
- Resume anticoagulants 24 hours after surgery if low risk of bleeding
- What are 12 High bleeding risk procedures?
- What are 10 Low bleeding risk procedures?
Low bleeding risk procedures
1. Abdominal hernia repair
2. Abdominal hysterectomy
3. Axillary node dissection
4. Bronchoscopy with or without biopsy
5. Carpal tunnel repair
6. Cataract eye surgery
7. Gastrointestinal endoscopy ± biopsy
8. Cholecystectomy
9. Knee and Hip replacement
10. Dental extractions
What are the 3 major factors that increase thromboembolic risk?
- Which scoring system can be used to estimate the thromboembolic risk of a patient with AF? What are the variables?
ESTIMATING THROMBOEMBOLIC RISK — the major factors that increase thromboembolic risk are:
1. Atrial fibrillation
2. Prosthetic heart valves
3. Recent venous or arterial thromboembolism (e.g., within the preceding 3 months).
What are the 3 large trials for anticoagulant use perioperatively? What were their results?
- When is thromboembolic risk greatest?
- When is VTE risk greatest?
- Should patients be screened for thrombophilias preoperatively?
- What is the risk of recurrent arterial embolism from any cardiac source after an acute event?
What is the definition of a major bleed?
Major bleeding is generally defined as bleeding that is:
1. Fatal
2. Intracranial
3. Requires surgery to correct
4. Lowers the haemoglobin by ≥2 g/dL
5. Requires transfusion of ≥2 units packed red cells; however, there is heterogeneity in definitions used by different clinicians.
What scoring system can be used to assess bleeding risk based on patient-related risks?
Once the thromboembolic and bleeding risks have been estimated, what decision needs to be made regarding the perioperative management of patients receiving anticoagulation?
- When would/wouldn’t you stop anticoags?
- Regardless of whether the patient’s anticoagulant is interrupted or continued, what practices should be employed to reduce bleeding and thromboembolic risks? (
Deciding whether to interrupt anticoagulation
- Once the thromboembolic and bleeding risks have been estimated, a decision can be made about whether the anticoagulant should be interrupted or continued. Data comparing the relative benefits of continuing anticoagulation versus interrupting an anticoagulant are limited, and decisions that balance thromboembolic and bleeding risks must be made on a case-by-case basis. No scoring system can substitute for clinical judgment in this decision making.
- In general, the anticoagulant must be discontinued if the surgical bleeding risk is high. Those at very high or high thromboembolic risk should limit the period without anticoagulation to the shortest possible interval; in some cases this involves the use of a bridging agent
- In contrast, individuals undergoing selected low bleeding risk surgery often can continue their anticoagulant; in certain cases, continuation of the anticoagulant may preferable.
Explain the 4 Settings in which anticoagulant interruption is required?
List 2 Settings in which continuing the anticoagulant may be preferable?
Warfarin
- MOA?
- Test of effect?
- Discontinuation? When to check INR?
Warfarin
- Use of Bridging Preoperatively?
- Restarting Warfarin and Postoperative bridging?
Dabigatran
- MOA?
- Discontinuation?
Dabigatran is a direct thrombin inhibitor; it reversibly blocks the enzymatic function of thrombin in converting fibrinogen to fibrin (factor IIa).
Dabigatran
- Use of Bridging Preoperatively?
- Restarting Dabigatran and Postoperative bridging?
Rivaroxaban
- MOA?
- Test of Effect?
Rivaroxaban is a direct factor Xa inhibitor; it reversibly blocks the enzymatic function of factor Xa in converting prothrombin to thrombin.
Rivaroxaban
- Discontinuation?
Rivaroxaban
- Use of Bridging Preoperatively?
- Restarting Rivaroxaban and Postoperative bridging?
Apixaban
- MOA?
- Test of Effect?
Apixaban is a direct factor Xa inhibitor; it reversibly blocks the enzymatic function of factor Xa in converting prothrombin to thrombin.
Apixaban
- Discontinuation?
Apixaban
- Use of Bridging Preoperatively?
- Restarting Apixaban and Postoperative bridging?
- In which patients on warfarin is bridging generally indicated? (7)
- For most other patients on warfarin with AF, the use of bridging anticoagulation is not generally indicated. Which study supports this?
- What does the study say about “rebound hypercoagability”?
Bridging anticoagulation may be appropriate in patients who have a very high thromboembolism risk who will have prolonged interruption of their anticoagulant (generally a vitamin K antagonist). Individual patient comorbidities that increase bleeding risk may also need to be considered because an increased postoperative bleeding risk may be a reason to avoid bridging. We suggest the use of bridging in individuals taking warfarin for one of the following conditions:
1. Embolic stroke or systemic embolic event within the previous 12 weeks
2. Mechanical mitral valve
3. Mechanical aortic valve and additional stroke risk factors
4. Atrial fibrillation and very high risk of stroke (e.g., CHADS2 score of 5 or 6, stroke or systemic embolism within the previous 12 weeks)
5. Venous thromboembolism (VTE) within the previous 12 weeks
6. Recent coronary stenting
7. Previous thromboembolism during interruption of chronic anticoagulation
A potential role for bridging in reducing the risk of “rebound hypercoagulability” has also been proposed; however, this premise is not supported by data from the BRIDGE trial discussed above.
Do we generally bridge patients on DOACs?
Bridging is generally not used for the shorter-acting direct oral thrombin inhibitors or factor Xa inhibitors. However, bridging may be appropriate for individuals on these agents who have a very high thromboembolic risk and a more prolonged interruption of their anticoagulant (e.g., due to postoperative intestinal ileus that prevents oral intake). (See ‘Dabigatran’ above and ‘Rivaroxaban’ above and ‘Apixaban’ above and ‘Edoxaban’ above.)
Do we bridge all patients with AF? When would you resume their warfarin?
Atrial fibrillation – As noted previously, we suggest not using bridging for most patients with atrial fibrillation. However, for those individuals for whom bridging is used due to a very high risk of thromboembolism, we use bridging both preoperatively and postoperatively. Warfarin is usually resumed within 24 hours after surgery, which may be the evening of the day after surgery or postoperative day two, as long as adequate haemostasis has been achieved.
What are the recommendations for bridging in a patient who has had a Venous thromboembolism:
- First month?
- Greater than one month?
Heparin product and dose
- What two types of heparin products are available? Pros & Cons of each? When would you use them?
- Do we use DOACs to bridge?
What are the 3 types of dosing for heparin?
- What is the dosing?
Therapeutic - enoxaparin, 1 mg/kg subcutaneously twice daily or dalteparin, 100 units /kg subcutaneously twice daily.
Prophylactic - enoxaparin, 1 mg/kg subcutaneously twice daily or dalteparin, 100 units /kg subcutaneously twice daily.
Preoperative timing of bridging
- When do we generally initiate heparin bridging before a planned procedure?
- When is LMW heparin discontinued?
- When is Unfractionated heparin discontinued?
Postoperative timing of bridging
- When is unfractioned/LMWH restarted postoperatively for bridging? Why?
- When is the peak anticoaglant activity?
- What must be achieved prior to recommencing bridging anticoagulation?
- In what situation would you delay the resumption of bridging anticoagulation postoperatively?
- When is warfarin recommenced postoperatively if the pt is being bridged with heparin?
Postoperative resumption of unfractionated heparin and LMW heparin is similar, based on the onset of anticoagulation at approximately one hour after administration for both forms of heparin, and peak anticoagulant activity at approximately three to five hours.
What is heparin-induced thrombocytopenia?
Heparin-induced thrombocytopenia (HIT) is a potentially life- threatening condition in which heparin-induced antibodies to platelets can cause thrombocytopenia and/or venous or arterial thrombosis. Patients with HIT should not receive any heparin (e.g., they should not receive heparin flushes, unfractionated heparin, or LMW heparin). Non-heparin anticoagulants need to be used in these patients.
What agents can be used to urgently reverse the following anticoagulants:
- Warfarin?
- Dabigatran?
- Rivaroxaban, apixaban, and edoxaban?
NEURAXIAL ANESTHESIA
- Should spinal or epidural anaesthesia be used in anticoagulated individuals?
- When should prophylactic dose LMWH be ceased prior to & recommenced after surgery with neuraxial anaesthesia?
- When should therapeutic dose LMWH be ceased prior to & recommenced after surgery with neuraxial anaesthesia?
- Neuraxial (ie, spinal or epidural) anaesthesia should not be used in anticoagulated individuals, due to the risk of potentially catastrophic bleeding into the epidural space. The increased risk of bleeding applies both at the time of catheter placement and the time of removal.
- If neuraxial anaesthesia is considered for surgical anaesthesia or postoperative pain control, the timing of anaesthesia and anticoagulant administration should be coordinated to optimize the safe use of both. Early consultation with the anaesthetist is advised.
Perioperative management of patients receiving anticoagulation.
- Outline the Thromboembolic risk for AF, prosthetic heart valves, & recent thromboembolism?
Perioperative management of patients receiving anticoagulation.
- Outline the Bleeding risk for different types of surgeries?
Perioperative management of patients receiving anticoagulation.
- Who gets bridging?
- What do we use to bridge?
- Timing of bridging? Would you rather recommence too early or too late?
What are the 6 main principles of perioperative medication management?
- Is it more common for medications to be mistakenly omitted or mistakenly given? Why?
Perioperative Medication Management - Beta Blockers
- List 2 several potential beneficial effects when taken peri-operatively?
- List 2 potential adverse effects of perioperative beta blockade?
- What can non-selective beta blockers interact with in the perioperative period?
Perioperative Medication Management - Beta Blockers
- To continue or discontinue? Why?
Continue
Perioperative Medication Management - Beta Blockers
- Formulations/Alternatives?
- 3 IV forms?
- What type of beta blocker is preferred?
Perioperative Medication Management - Alpha 2 agonists
- Benefit/risk - Clonidine? which study?
- Continue/discontinue?
- Formulations/Alternatives - Clonidine?
Continue but don’t initiate preoperatively.
Perioperative Medication Management - Calcium Channel Blockers
- Benefit/risk?
- Continue/discontinue?
- Formulations/Alternatives - What should be avoided?
Continue in patients who are already taking them preoperatively.
Perioperative Medication Management - ACE inhibitors and angiotensin II receptor blockers
- Benefit/risk?
- Continue/discontinue?
- Formulations/Alternatives - IV?
Reasonable to continue in patients with congestive heart failure or hypertension but decision needs to be individualised. Some anaesthetists may prefer to withhold these medications on the morning of surgery based on concerns about possible hypotension.
Perioperative Medication Management - Diuretics
- Benefit/risk - Which 2 physiological effects of loop and thiazide-type diuretics are of concern?
- Continue/discontinue?
- Formulations/Alternatives?
No consensus but in general we recommend they be held on the morning of surgery, and resumed when the patient is taking oral fluids - will depend on assessment of volume status. Can always give IV intraop if you have witheld but may increase the risk of hypotension if given in AM.
Perioperative Medication Management - Non-statin hypolipidemic agents
- Benefit/risk?
- Continue/discontinue?
Discontinuation of niacin, fibric acid derivatives, bile sequestrants, and ezetimibe 1 day before surgery
Perioperative Medication Management - Digoxin
- Benefit/risk?
- Continue/discontinue? Do you need to check the drug level?
- Formulations/Alternatives?
Formulations/alternatives – IV digoxin is available if needed.
Perioperative Medication Management - Statins
- Benefit/risk?
- Continue/discontinue? Interactions?
- Formulations/Alternatives?
- Continue but dose adjust for hepatic or renal hypoperfusion or injury.
- Start statins for patients undergoing vascular surgery.
- No interactions with anaesthetics
Perioperative Medication Management - H2 blockers and proton pump inhibitors
- Benefit/risk?
- Continue/discontinue? Interactions?
- Formulations/Alternatives?
Continue
Perioperative Medication Management - Inhaled beta agonists and anticholinergics
- Benefit/risk?
- Continue/discontinue?
- Formulations/Alternatives?
Continue, including day of surgery.
- Formulations/alternatives – Inhaled beta agonists and anticholinergics are normally administered on the morning of surgery. The drugs can be administered through a nebulizer or in the circuit of the ventilator when use of metered-dose inhalers is not possible.
Perioperative Medication Management - Pulmonary Agents: Glucocorticoids
- Benefit/risk?
- Continue/discontinue?
Perioperative Medication Management - Pulmonary Agents: Leukotriene inhibitors
- Benefit/risk?
- Continue/discontinue?
- Formulations/alternatives?
Give on the morning of surgery and resume when the patient is tolerating oral medications.
Perioperative Medication Management - Endocrine Agents: Glucocorticoids
- Continue/discontinue? What doses and for how long?
Perioperative Medication Management - Oral Contraceptives
- Benefit/Risk? What doses?
- Continue/discontinue?
Perioperative Medication Management - Postmenopausal hormone therapy (HRT)
- Benefit/Risk?
- Continue/discontinue?
High VTE risk procedures - cease 4-6 weeks prior
Perioperative Medication Management - Selective estrogen receptor modulators
- Benefit/Risk?
- Continue/discontinue?
SERMs for prevention of cancer or osteoporosis - cease 4-6 weeks prior if moderate to high VTE risk surgery. Consult oncology.
Perioperative Medication Management - Drugs used for thyroid disease
- Continue/discontinue?
- Formulations/Alternatives?
Perioperative Medication Management - Drugs used for osteoporosis/osteopenia
- Benefit/Risk?
- Continue/discontinue?
Perioperative Medication Management - Aspirin
- Benefit/Risk? MOA?
- Continue/discontinue?
Continue/discontinue based on type of surgery.
Perioperative Medication Management - Other antiplatelet agents: clopidogrel, prasugrel, ticagrelor, and ticlopidine
- MOA?
- Benefit/Risk?
Except for emergent settings, we recommend that surgery be delayed and therapy with P2Y12 receptor blocker and aspirin be continued for at least the minimum recommended duration for each stent type.
- Cease aspirin
- Consult cardiology if within timeframe
Perioperative Medication Management - Nonsteroidal anti-inflammatory drugs
- MOA?
- Benefit/Risk?
- Continue/discontinue?
- Formulations/alternatives?
Benefit/risk – The antiplatelet effects of NSAIDs are due to reversible
inhibition of COX-1, an isoform of cyclooxygenase, leading to decreased production of thromboxane A2 (TxA2). TxA2 is released by platelets in response to a number of agonists, leading to platelet aggregation. These antiplatelet effects increase the bleeding risk perioperatively but, like aspirin, may reduce the risk of perioperative vascular events. The selective COX-2 inhibitors, such as celecoxib, have minimal effects on platelet function, although the potential for renal toxicity remains. Most selective COX-2 inhibitors and nonselective NSAIDs appear to have deleterious cardiovascular effects. Non-acetylated nonsteroidals, such as salsalate, do not have an antiplatelet effect.
- List 6 Medications/agents used in the perioperative period that may lead to AKI?
- List 3 Psychotropic agents that may need to be ceased perioperatively?
Several medications and agents used during the perioperative period may lead to AKI, including:
1. NSAIDs
2. ACE inhibitors
3. Angiotensin II receptor blockers
4. Diuretics
5. Antibiotics (e.g., aminoglycosides, vancomycin)
6. IV contrast agents.
Optimizing volume status and medications to prevent acute tubular necrosis are an important principle of perioperative care in patients with renal impairment.
Discuss the perioperative management of the following herbal medications:
1. Ephedra (ma huang)?
2. Garlic?
3. Gingko?
4. Ginseng?
5. Kava?
6. St John’s Wort?
7. Valerian?
8. Echinacea?
Herbal medications, used frequently, may have effects that could be deleterious in the perioperative period, including clotting abnormalities and interactions with anaesthetics. Clinicians should specifically inquire about herbal medication use in presurgical patients, as patients often do not readily disclose use. There is no evidence that herbal medications improve surgical outcomes, and there are theoretic reasons that these agents may increase perioperative morbidity. For simplicity and because the purity and nature of some herbal medications is unclear, we recommend stopping herbal agents at least one week before surgery.
Why is careful assessment of patients with diabetes prior to surgery required? What are they at increased risk of postoperatively?
Perioperative management of blood glucose in adults with diabetes mellitus
- What is involved in the preoperative evaluation of patients with DM?
- Clinical evaluation?
- History? (8)
Clinical evaluation — The preoperative evaluation of any patient, including those with diabetes mellitus, focuses on cardiopulmonary risk assessment and modification. Coronary heart disease is much more common in individuals with diabetes than in the general population, and in addition, patients with diabetes have an increased risk of silent ischemia. Therefore, assessment of cardiac risk is essential in patients with diabetes. Other associated conditions, such as hypertension, obesity, chronic kidney disease, cerebrovascular disease, and autonomic neuropathy, need to be assessed prior to surgery as these conditions may complicate anaesthesia and postoperative care.
Perioperative management of blood glucose in adults with diabetes mellitus
- 4 baseline investigations?
What effect does surgery have on glucose control?
What are the 4 general goals of perioperative diabetes management?
Perioperative management of blood glucose in adults with diabetes mellitus
- What Glycaemic targets should be aimed for?
Aim to keep glucose readings between 140 and 200 mg/dL (7.8 to 11 mmol/L)
Perioperative management of blood glucose in adults with T2D treated with diet alone
- Ideally when should patients with DM have their surgeries?
- How are patients with Type 2 diabetes treated with diet alone managed preoperatively?
- List 4 examples of short/rapid-acting insulin formulations? How often are these given?
- When should Blood glucose levels be checked in these patients?
- Which surgeries require intraoperative glucose testing? How is that done?
Ideally, all patients with diabetes mellitus should have their surgery prior to 9 AM to minimize the disruption of their management routine while being nil per os (NPO).
Perioperative management of blood glucose in adults with T2D treated with oral hypoglycaemic agents/noninsulin injectables
- When should they cease their meds?
- What is the risk with Sulfonylureas?
- What is the risk with metformin?
- What is the risk with thiazolidinediones?
- What is the risk with SGLT-2 inhibitors?
- When can these agents be recommenced postoperatively?
Perioperative management of blood glucose in adults with T1DM or T2DM treated with insulin
- When should they cease their meds if their surgery is a minor, early morning procedure where breakfast is likely only delayed?
Perioperative management of blood glucose in adults with T1DM or T2DM treated with insulin
- When should they cease their meds if their surgery is a morning procedure where breakfast and possibly lunch are likely to be missed or for surgeries that take place later in the day? (7 points)
- In patients with TIDM, do they still need insulin even in the absence of oral intake?
Basal metabolic needs utilize approximately one-half of an individual’s insulin even in the absence of oral intake; thus, patients should continue with some insulin even when not eating. This is mandatory in type 1 diabetes to prevent ketoacidosis.
How are patients with either TIDM or TIIDM treated with insulin undergoing long and complex procedures managed?
What is a GIK solution?
- Contents?
- Infusion rate?
Combined glucose insulin potassium (GIK) solution
Separate insulin and glucose intravenous solutions
- Dextrose doses?
- Infusion rates?
- How often should capillary glucose levels be checked?
Describe the management of patients with diabetes post-operatively.
- Generally, when can the preoperative diabetes treatment regimen be reinstated?
- In which instances should metform not be restarted postoperatively? (3)
- When and how should Sulfonylureas be reinstated postoperatively? Why?
- In which instances should Thiazolidinediones not be restarted postoperatively? (3)
- How should a patient who has been on an insulin infusion be managed postoperatively?
- How should a patient who was taking subcutaneous insulin in the early postoperative phase be managed before food is restarted?
What is the definition of Correction Insulin and when is it given?
- Why should correction insulin never be the sole insulin regimen in type 1 diabetes? What about for type 2 diabetics?
Although correction insulin alone should not be used as the sole treatment for patients with type 1 or insulin-treated type 2 diabetes, correction insulin alone may be used as initial insulin therapy or as a dose-finding strategy in patients with type 2 diabetes previously treated at home with diet or an oral agent, who will not be eating regularly during hospitalization. In this setting, it is typically administered every 6 hours as regular or rapid-acting insulin, until the patient is eating and either can resume oral agents or a basal-bolus regimen is initiated.
- At what glucose levels should clinicians become concerned about the possibility of hypoglycaemia in a perioperative patient?
- How is this managed?
- Symptoms?
- Clinicians should become concerned about the possibility of hypoglycaemia in a perioperative patient when glucose levels are ≤70 mg/dL (3.9 mmol/L).
Perioperative Management of blood glucose in adults with diabetes - Special considerations: Glucocorticoids
- What are they often given as perioperatively? Dose?
- What effect do they have on pre-existing diabetes mellitus?
- When can oral hypoglycaemic medications can be used in patients with on steroids? When is insulin necessary?
- What effect does morning prednisone have on glucose levels? How is this combatted?
Perioperative Management of blood glucose in adults with diabetes - Special considerations: Hyperalimentation
- What effect does TPN have on blood glucose levels?
- What is the recommended insulin infusion regimen?
Perioperative Management of blood glucose in adults with diabetes - Special considerations: Emergency procedures’
- When emergency surgery is required in a patient with diabetes with either very high or very low blood glucose levels, how often should their BSLs be checked?
- What is the recommended insulin regimen for these patients?
Evaluation of preoperative pulmonary risk
- Overall, are pulmonary or cardiovascular complications more common post-operatively?
- Definition of postoperative pulmonary complications?
- 5 Examples?
In a study of patients undergoing elective abdominal surgery, as an example, pulmonary complications occurred significantly more often than cardiac complications and were associated with significantly longer hospital stays. The National Surgical Quality Improvement Program (NSQIP) also found that postoperative pulmonary complications were the most costly of major postoperative medical complications (including cardiac, thromboembolic, and infectious) and resulted in the longest length of stay. The rate of postoperative pulmonary complications across all types of surgery was 6.8% in a systematic review of studies that provided explicit outcome definitions.
PERIOPERATIVE PULMONARY PHYSIOLOGY
- What pattern of lung volume reduction are thoracic and upper-abdominal surgery associated? What appears to play the most important role in these changes? 2 other factors?
- What causes this reduction in lung volume postoperatively?
How can risk factors for pulmonary complications be grouped?
- List 11 potential patient-related factors?
- Explain the impact of increasing age as a risk factor for post-operative pulmonary complications?
Risk factors for pulmonary complications can be grouped into patient-related and procedure-related risks. The potential patient-related factors that have been studied include the following:
1. Age
2. COPD
3. Asthma
4. Smoking
5. General health status
6. Obesity
7. Obstructive sleep apnoea
8. Pulmonary hypertension
9. Heart failure
10. Upper-respiratory infection
11. Metabolic factors
Evaluation of Preoperative Pulmonary Risk
- What is the prohibitive level of pulmonary function below which surgery is absolutely contraindicated?
- Explain the impact of asthma as a risk factor for post-operative pulmonary complications?
- Explain the impact of smoking as a risk factor for post-operative pulmonary complications?
Despite the increased risk of postoperative pulmonary complications in patients with obstructive lung disease, there appears to be no prohibitive level of pulmonary function below which surgery is absolutely contraindicated. This was illustrated in a study of 12 very high-risk patients as defined by older criteria of inoperability (FEV1 <1 litre) in which only 3 of 15 surgeries were associated with postoperative complications and no deaths occurred. In another report of surgery in patients with severe COPD (FEV1 <50 percent predicted), mortality was 5.6 percent (primarily related to a high mortality rate after cardiac surgery) and severe postoperative pulmonary complications occurred in 6.5 percent. The benefit of surgery must be weighed against the known risks; even very high-risk patients may proceed to surgery if the indication is sufficiently compelling.
Evaluation of Preoperative Pulmonary Risk
- Is obesity a risk factor for post-operative pulmonary complications?
Evaluation of Preoperative Pulmonary Risk
- Is pulmonary hypertension a risk factor for post-operative pulmonary complications?
- Is pulmonary hypertension a risk factor for post-operative pulmonary complications?
Heart failure — the risk of pulmonary complications may be higher in patients with heart failure than in those with chronic obstructive pulmonary disease. The original Goldman cardiac risk index has been shown to predict postoperative pulmonary as well as cardiac complications. Although the Revised Cardiac Risk Index is now more commonly used to estimate risk for cardiovascular complications, validation studies of the revised index in predicting pulmonary complications have not been done.
Outline the ASA Scoring System.
Evaluation of Preoperative Pulmonary Risk
- Are upper respiratory tract infections considered a risk factor for post-operative pulmonary complications?
- Which 2 Metabolic factors are considered risk factors for post-operative pulmonary complications?
What are the 4 Procedure related risk factors for postoperative pulmonary complications?
- What is the single most important factor in predicting the overall risk of postoperative pulmonary complications?
- Which surgical sites carry higher risk?
- Surgical site
- Duration of surgery
- Type of anaesthesia
- Type of neuromuscular blockade
Additionally, emergency surgery increases the risk for pulmonary complications.
- What is the role of Duration of surgery as a risk factor for postoperative pulmonary complications?
- What is the role of Type of Anaesthesia as a risk factor for postoperative pulmonary complications?
- What is the role of Type of Neuromuscular blockade as a risk factor for postoperative pulmonary complications?
Duration of surgery — Surgical procedures lasting >3-4 hours are associated with a higher risk of pulmonary complications. For example, a study of risk factors for postoperative pneumonia in 520 patients found an incidence of 8% for surgeries lasting <2hrs hours versus 40% for procedures lasting >4hrs. This observation suggests that, when available, a less ambitious, briefer procedure should be considered in a very high risk patient.
Type of neuromuscular blockade — Residual neuromuscular blockade can cause diaphragmatic dysfunction, impaired mucociliary clearance, and ultimately contribute to postoperative pulmonary complications. Residual neuromuscular blockade is also an important risk factor for critical respiratory events in the immediate postoperative period.
What history and physical exam findings should you assess for in a preoperative pulmonary risk assesment?
Evaluation of preoperative pulmonary risk
- Which 4 investigations of the respiratory system would you consider?
- What is the role of preoperative pulmonary function testing for risk stratification?
- What are 2 reasonable goals that could potentially justify the use of preoperative PFTs?
- Outline a reasonable approach to patient selection for preoperative pulmonary function testing?
All candidates for lung resection should have preoperative pulmonary function tests performed. For all other procedures, laboratory tests serve as adjuncts to the clinical evaluation and should be obtained only in selected patients. Potential preoperative laboratory tests include the following:
1. Pulmonary function tests (PFTs)
2. Arterial blood gas analysis
3. Chest radiographs
4. Exercise testing
Evaluation of preoperative pulmonary risk
- Role of Exercise testing in preop risk stratification for postop pulmonary complications?
- Who should get a pre-op CXR?
- Should we use preoperative arterial blood gas analyses to stratify risk for postoperative pulmonary complications?
Chest radiographs — abnormal chest x-rays are seen with increasing frequency with age. However, chest x-rays add little to the clinical evaluation in identifying healthy patients at risk for perioperative complications. The available literature does not allow an evidence-based determination of which patients will benefit from a preoperative chest x-ray. In my opinion, it is reasonable to obtain a preoperative chest x-ray in patients with known cardiopulmonary disease and in those over age 50 years undergoing high risk surgical procedures, including upper abdominal, aortic, oesophageal, and thoracic surgery.
Assessment Of Post-Operative Pulmonary Risk
- List 3 Risk prediction tools used to estimate the risk of postoperative pulmonary complications? Pros & Cons of each?
- What 7 risk factors are considered in the The ARISCAT Risk Index?
- 2 Gupta calculators?
Gupta calculator for postoperative respiratory failure - uses multiple preoperative factors to predict risk of failure to wean from mechanical ventilation within 48 hours of surgery or unplanned intubation/ reintubation postoperatively. Although this calculator is too complicated to perform manually, it may be downloaded for free, or accessed online.
Gupta calculator for postoperative pneumonia - derived in a similar manner to the respiratory failure calculator. It also may be downloaded for free online.
Obstructive Sleep Apnoea
- What is it?
- Prevalence?
- How does it cause clinical manifestations?
- Incidence of perioperative complications in patients with OSA?
- Recommendations?
Clinical manifestations of OSA are caused by recurrent collapse of the pharyngeal airway during sleep, leading to intermittent hypercapnia and hypoxemia.
OSA - Perioperative Risks
- 4 Postoperative complications/ adverse effects?
- What are the 2 most important determinants of perioperative risk in patients with OSA?
List and explain 5 perioperative/ anaesthetic factors that exacerbate OSA disease severity and contribute to an increased risk of complications postoperatively.
More invasive surgical procedures may have higher risk for complications, because they typically require more anaesthetic agents, sedatives, and opioids, and because they are more likely to affect airway and cardiorespiratory function.
Postoperative Complications in Patients with OSA
- What respiratory complications are they at a higher risk of?
- What cardiovascular complications are they at a higher risk of?
- What is the association between OSA and perioperative mortality?
- 5 Other complications they are at increased risk of postoperatively?
The incidence of perioperative complications is increased by a factor of 2-4 fold in patients with OSA. Respiratory complications are the most common. While unproven, it is likely that patients with more severe OSA are at greater risk. High-risk surgical procedures are those that are invasive, involve the airways or cardiovascular system, or are associated with need for high levels of postoperative opioids.
Who should be screened for OSA preoperatively?
- 4 critical populations to screen?
INITIAL ASSESSMENT — Preoperative patients should be screened for obstructive sleep apnoea (OSA), and those with the diagnosis or suspicion of OSA are assessed for the severity and adequacy of management.
Outline the Mallampati scoring system.
The Mallampati score assesses anatomy to determine risk for apnea or hypopnea episodes.
Are screening tools helpful to assess for OSA? When are they helpful?
- Give one example of a screening tool used for OSA?
There are multiple screening tools available to help identify individuals who may have OSA. The sensitivity of these tools is generally higher than their specificity. The high false positive rate of questionnaires diminishes their diagnostic value such that when the score is high, patients do not always have OSA; in contrast, when the score is low, patients are unlikely to have OSA. Thus, questionnaires are generally only helpful when they are negative (i.e., low score), and patients with positive screening need further evaluation to diagnose OSA. Some screening tools (e.g., STOP-Bang) may be used with a higher cut-off score to increase specificity.
How should patients with known OSA be assessed preoperatively?
- What do you want to know?
- What index is reported for OSA in sleep studies?
- How is severity graded?
Assessment of OSA
Preoperative evaluation of patients with OSA should specifically include assessment of severity and adequacy of management of OSA. Patients with severe or poorly-controlled OSA, or otherwise at high risk of perioperative complications, may benefit from initiation or optimization of treatment before surgery.
List 6 OSA associated conditions that may require preoperative optimization, affect the decision to operate, or change the management of anaesthesia.
- Prevalence of OHS?
- List 2 valuable clinical predictors of OHS on ABG?
- What investigation might you consider in a patient with moderate/severe OSA +/- right heart strain?
Which 3 patient groups are considered high-risk patients on the basis of OSA (known or suspected)?
- Would you delay surgery to implement OSA treatments for preoperative optimisation?
- What is the rational for beginning OSA treatment prior to surgery?
- How long after initiating OSA treatment preoperatively would you reschedule the surgery for?
High-risk patients on the basis of OSA (known or suspected) include:
1. Patients with known moderate or severe OSA that is not optimally managed (current signs and symptoms, particularly excessive sleepiness, observed apneas, and hypercapnia; nonadherence or technical difficulty with therapy; excessive weight gain since the last evaluation).
2. Patients with high risk of OSA based on screening.
3. Patients with significant medical comorbidities, particularly if not adequately evaluated and managed
- When should CPAP treatment for OSA be ceased prior to surgery?
- Which patients are generally considered reasonable candidates for outpatient surgery? (3)
- Which patients with OSA may not be suitable as an outpatient? (4)
MANAGEMENT OF PATIENTS PROCEEDING TO SURGERY — All patients treated for OSA should be encouraged to continue current therapy up to the day of surgery. Patients expected to remain overnight in the hospital may be asked to bring continuous positive airway pressure (CPAP) equipment, depending on hospital protocol.
Postoperative Management of Adults with OSA
- Should oxygen therapy be iniated?
- How should they be monitored?
- Which patients with OSA are at risk of hypercapnia with oxygen therapy?
OXYGENATION AND VENTILATION — Oxygen therapy is routine in most postoperative recovery areas; standard monitoring in the post-anaesthesia care unit (PACU) includes oxygenation, ventilation, circulation, level of consciousness, and temperature. Because the incidence of perioperative respiratory and other complications is higher in patients with OSA, oxygen therapy is often prolonged, and the intensity and the duration of close monitoring are greater than for patients without OSA.
Postoperative Management of Adults with OSA
- Should ventilation be separately assessed to oxygen therapy in postoperative patients with OSA?
- How is ventilation assessed? Why is chest wall impedance (detected by ECG) a less favourable method of assessing ventilation?
- Which investigation provides the most precise measure of ventilation?
- Which 3 respiratory events should be specifically noted?
What are the indications for the use of CPAP postoperatively in patients with OSA?
- What about in upper GI surgery patients? Will it increase the risk of anastamotic leaks?
Use of CPAP in the PACU
- What is a reasonable CPAP level to commence a patient who does not know their level but used CPAP preoperatively?
- When the sole goal of positive airway pressure is to maintain upper airway patency, what CPAP pressure range is used?
How should a patient with OSA be positioned postoperatively?
Positioning — Because the supine position worsens OSA in some patients, it is prudent to maintain postoperative OSA patients in the lateral or semi-upright position, if not contraindicated by the surgical procedure. While no studies have specifically associated positioning with perioperative outcomes, studies in nonsurgical patients with OSA have shown that sleeping in a non-supine position improves the apnoea hypopnea index and oxyhemoglobin saturation, while a change in position from lateral to supine increases the passive pharyngeal collapsibility. A prospective cohort study also demonstrated that postoperative patients spent more time in the supine position and that the apnoea hypopnea index was significantly greater while in this position.
How should pain be controlled postoperatively in patients with OSA?
- Why avoid opioids?
- List 8 opioid-sparing analgesic techniques?
- Concurrent sedative and opioid use?
- Antagonist for opioids?
- Antagonist for benzodiazepines?
- What is the “pain sedation mismatch”?
Pain control for postoperative patients with OSA should minimize the use of systemic opioids. Strategies include nonopioid analgesics (e.g., acetaminophen, nonsteroidal anti-inflammatory drugs), peripheral nerve blocks, and neuraxial analgesia. When opioids are required for pain control, adverse effects can be mitigated by using low doses, patient- controlled analgesia without baseline infusion, shorter-acting agents, and more intensive monitoring.
Postoperative Management of Adults with OSA
- List 7 PACU discharge criteria and factors determining disposition of the patient?
DISCHARGE TIMING AND DISPOSITION
- Patients at low risk for complications (e.g., mild obstructive sleep apnoea [OSA], minor surgery, and no opioid use) who do not have respiratory events in the post-anaesthesia care unit (PACU) may generally be discharged to home or to an unmonitored hospital bed.
- It is prudent to prolong intensive monitoring of patients at higher risk, or who have recurrent respiratory events in the PACU, by delaying discharge to home or admitting to a monitored environment with continuous oximetry. Additional events in an unmonitored home environment may lead to poor outcomes. While objective data are sparse on which patients are at risk of adverse outcomes after discharge from the PACU, experts have described algorithms and scoring systems to determine which patients benefit from continued monitoring.
- For how long is the risk for respiratory complications postoperatively increased in patients OSA?
- When does normal sleep architecture resume postoperatively?
- When are night breathing disturbances greatest?
In patients with OSA, disturbance in sleep architecture is greatest on postoperative night 1; however, breathing disturbances are greatest on postoperative night 3 and may not normalize for several more nights. Patients using CPAP therapy should be instructed to consistently use CPAP during this period whenever sleep is likely, including the daytime.
What is the Opioid Risk Tool?
- 5 components?
Pharmacology of Resuscitation
Give examples of the following medications:
- 2 β sympathomimetics?
- 2 Vasopressors?
- 1 PNS antagonist?
- 1 Vasodilator?
- 1 Antihypertensive used in resus?
- 1 Antiarrhythmic?
- 3 Anaesthetic agents?
- 2 Neuromuscular blockers?
- What does Pharmaceutics involve?
- Difference between Pharmacokinetics vs. Pharmacodynamics?
Pharmaceutics
* Packaging, mixing, adjuvants etc..
* What can it be diluted in?
* Dosing
Autonomic Receptors
Sympathetic NS
- Which 2 agonists?
- alpha-1 receptors: where? effect?
- alpha-2 receptors: where? effect?
- beta-1 receptors: where? effect?
- beta-2 receptors: where? effect?
- beta-3 receptors: where? effect?
Parasympathetic NS
- Which agonist?
- M1?
- M2?
- M3?
ANS and the Heart - Terminology - Define the following terms:
* Inotrope?
* Vasopressor?
* Chronotrope?
* Dromotrope?
* Lusiotrope?
- Inotrope = a drug that alters the force or energy of muscular contractions.
- Vasopressor = a drug which causes the constriction of blood vessels.
- Chronotrope = drug that changes heart rate.
- Dromotrope = a druge which affects the conduction speed in the AV node, and subsequently the rate of electrical impulses in the heart.
- Lusiotrope = drugs that alter the rate of myocardial relaxation
- What is the rhythm?
- What is your management as per ALS algorithm?
- List 8 drugs you might use in a resuscitation like this?
= Ventricular Fibrillation - chaotic and disorganised electrical activity with no identifiable QRS complexes. VF is initially coarse and will progress to fine VF and eventually asystole if prompt defibrillation is not performed = SHOCKABLE
Drugs to consider:
1. Adrenaline
2. Amiodarone
3. Vasopressin
4. Lignocaine
5. MgSO4
6. KCl
7. HCO3/Bicarbonate
Adrenaline
- Class of Drug/MOA - Which receptors?
- Pharmaceutics - concentrations?
- Dose - cardiac arrest? Anaphylaxis? Shock? Infusion? Airway oedema?
- Pharmacokinetics - route? metabolism? metabolites?
- Pharmcodynamics? (3)
Adrenaline - Pharmacodynamics
- α and β effects – tachycardia, inotropy, HTN, bronchodilation, hyperglycaemia, etc
- Stabilises mast cell degranulation.
- In cardiac arrest: theoretically, adrenaline’s vasopressor effect maintains enough coronary perfusion that ROSC is possible, and also preserve some perfusion other critical organs.
Amiodarone
- Class of Drug/MOA?
- Dose - cardiac arrest? Infusion?
- Pharmacokinetics - route? half-life? effect hangover?
- Pharmcodynamics - 6 complications?
Vasopressin
- Also known as?
- Which receptors?
- Dose & Route?
- 3 ANZCOR Recommendations for vasopressin use in resuscitation?
Lignocaine
- Class? MOA?
- Which receptors?
- Dose?
- Toxicity?
- 3 ANZCOR Recommendations for Lignocaine use in resuscitation?
Lignocaine
* Local Anaesthetic, Class I anti-arrhythmic (acts via Na channels)
* Dose 1mg/kg bolus
* In higher doses (>3mg/kg) can cause systemic toxicity (seizures, CVS collapse)
* ANZCOR Recommendations: “Lignocaine may be used as an alternative to amiodarone in patients with refractory VF/pVT (weak recommendation, very low quality evidence)”
MgSO4
- Class? MOA?
- Which receptors?
- Dose?
- Toxicity?
- 3 ANZCOR Recommendations for Lignocaine use in cardiac arrest?
- 5 Indications for magnesium use?
MgSO4
* Mg is an electrolyte essential for membrane stability
* Hypomagnesaemia causes myocardial hyperexcitability particularly in the presence of hypokalaemia and digoxin
* Pharmaceutics: MgSO4 49.3% = 2.47g in 5ml = 10mmol
* ANZCOR Recommendations: “Magnesium should not be routinely used in adult cardiac arrest, but should be given for hypomagnesemia and torsades de pointes”
Potassium - KCl
- Symptoms of low K?
- Pharmaceutics - doses?
- ANZCOR Recommendations for KCl in resus?
Bicarbonate - HCO3
- What does it do?
- Pharmaceutics?
- 4 Uses?
- ANZCOR Recommendations for use of HCO3 for treatment of cardiac arrest?
What are the ANZCOR Guidelines regarding use of vasopressors (adrenaline or vasopressin) in resuscitation?
Although there is evidence that vasopressors (adrenaline or vasopressin) may improve return of spontaneous circulation and short-term survival, there is insufficient evidence to suggest that vasopressors improve survival to discharge and neurologic outcome.
Case 2 - After successfully resuscitating patient 1, you feel the urgent need for caffeine. On your way back to the DCR an elderly gentleman collapses in front of you. You are the first at the scene. He is on the ground, non responsive but making groaning sounds. You feel his pulse – it is ~30bmp. You call for help and soon after the resus trolley arrives and the ECG rhythm can be assessed. Which drugs will help in the resuscitation of this patient?
Definition of Mobitz II block (Hay Block): A form of 2nd degree AV block in which there is intermittent non-conducted P waves without progressive prolongation of the PR interval.
Atropine
- Class of Drug/MOA?
- Concentration?
- Dose?
- Pharmacokinetics?
- Onset?
- Pharmacodynamics - SEs?
Isoprenaline
- Class of Drug/MOA?
- Pharmaceutics - Concentration? Dose?
- Pharmacokinetics?
- Pharmacodynamics - Which receptors?
List 4 indications for pacing in cardiac arrest?
- 2 types of pacing?
- What are the steps for transcutaneous pacing?
Pacing
Indications: Patients who fail to respond to pharmacotherapy, or are at high risk of asystole, for example:
1. Recent asystole
2. Mobitz II AV block
3. Complete heart block
4. Ventricular standstill >3sec
- Transcutaneous vs Transvenous
Case 3 - You are about to sit down to lunch when your registrar calls you down to ED to urgently admit a patient. He is a 81y.o. man with sepsis secondary to a prosthetic joint infection. He is Febrile (38.7°C), tachycardic (HR 110bpm) and hypotensive (BP 80/45), despite 2L of crystalloid. Antibiotics have been commenced, and he has been booked for theatre. What 3 other drugs could help resuscitate this patient?
- Metaraminol
- Noradrenaline
- Vasopressin
Metaraminol
- Class of Drug/MOA?
- Pharmaceutics - Concentration? Doses?
- Pharmacodynamics? (4)
Metaraminol
- Class of Drug/MOA = Vasopressor - α1 agonist
Pharmaceutics
- 10mg in 1ml – typically diluted in 20ml syringe.
- Easily titratable - 1ml (0.5mg) boluses PRN
Pharmacokinetics
- Safer peripheral administration as lower potency
- Rapid metabolism
Pharmacodynamics
- Arterial and venous vasoconstriction
- Baroreceptor mediated ↓HR.
- Increased SVR and afterload
- Potentially decreased CO
Noradrenaline
- Class of Drug/MOA?
- Pharmaceutics - Concentration? Doses?
- Pharmacokinetics? (2)
- Pharmacodynamics? (2)
Noradrenaline
- Class of Drug / MOA = Vasopressor – predominant α1 activity, but some β1 also. Little β2
- Pharmaceutics = 4mg in 4ml, Administered via infusion 1-40mcg/min
Pharmacokinetics
- Potent. Administer via CVC
- Rapid metabolism by MAO and COMT
Pharmacodynamics
- Arterial and venous vasoconstriction increased BP
- Increased SVR and afterload, however CO generally maintained
Vasopressin
- Class of Drug/MOA?
- Pharmaceutics - Concentration? Doses?
- Pharmacokinetics? (2)
- Pharmacodynamics? (2)
Case 4 - After stabilising your septic patient, your pager promptly goes off. An 87y.o. man under your care recently returned to the ward following a hemiarthroplasty for #NOF. He had a general anaesthetic and awoke highly agitated and in pain, requiring fentanyl and midazolam to sedate him. His is barely rousable, has a respiratory rate of 3 breaths/min and is desaturating to 85% on a HM 6L/min. What 2 drugs might help in the situation?
- Naloxone = Competitive opioid receptor antagonist
- Flumazenil = Competitive antagonist of the benzodiazepine receptor (on the GABAA receptor)
Naloxone
- Class of Drug / MOA?
- Pharmaceutics - Concentration & Dose?
- Pharmacokinetics?
- Pharmacodynamics?
Flumazenil
- Class of Drug / MOA?
- Pharmaceutics - Concentration & Dose?
- Pharmacokinetics?
- Pharmacodynamics?
- What is the Scope of Anaesthesia required at the level of the medical student?
- What is the Philosophy of Anaesthesia?
- How to size & place a guedel airway
- Chronic Pain – Biopsychosocial approach
Preoperative Assessment
- Focus on cardiorespiratory reserve
- Current comorbidities & implications on anaesthetics & surgery
- Can the patient’s condition be optimised?
- Usually thorough history & assessment with a focus on CVS & Resp & Pain (appropriate expectations – need to stay on opioids if been on for a while)
- Give all meds as prescribed EXCEPT antiplatelets/Anticoags & Diabetic meds (oral Sulphonylureas/insulin)
Why do we perform an airway assessment preoperatively?
- Head tilt, chin lift, jaw thrust
- Size & insert a guedel = Oxygen
- Put in recovery position if breathing
- Not breathing = bag valve mask
- MET Call
- Always call for help immediately with severe stridor!
Fasting Status required for surgery?
4 issues associated with fasting for surgery?
Fasting Status
- Protocols vary but must anaesthetics accept 6 hours for food and 2 hours for clear fluids
- Even with “appropriate fasting”, some patient have significant stomach contents
- Bowel obstruction, diabetes, renal disease
- Alcohol, injury, opioids in the ED
- Risk of full stomach vs. risk of delay
Describe the principles of Post-operative pain control?
What do the APS do?
Control of Postoperative Pain
Be alert to the patient with unexpectedly high levels of post-op pain
- Chronic pain patients
- Surgical complication
WHO Ladder
- Paracetamol = opioid sparing, chart 1g QID regularly (not PRN) for at least 48 hours
- NSAIDs & Tramadol
- Opioids
Remember multimodal analgesia (synergism and opioid sparing) - Consider regional blocks
Post-operative Pain - NSAIDs/COX2 Inhibitors
- 5 Cautions?
6 Side effects of opioids?
Troubleshooting postop pain - 5 questions to ask yourself?
Troubleshooting postop pain
1. Is there a surgical complication? – General assessment required
2. Does the patient have opioid tolerance?
3. Does the patient have chronic pain?
4. Is an appropriate analgesia regimen charted?
5. Is what is charted being given?
Post-operative Pain - Local Anaesthetic Agents
- Routes of delivery?
- Toxicity?
- 3 Examples & their dosing?
Local Anaesthetic Agents
LA
- Single shot
- Catheter and infusion
Can be injected
- Locally - field block
- Regional - eg. interscalene or femoral n blocks
- Central neuraxial blockage - epidural
Post-operative N&V
- 7 Factors affecting it?
- 4 types of drugs & examples?
PONV - Factors
1. Age
2. Type of surgery
3. Females
4. Previous PONV
5. h/o motion sickness
6. Opioids for postoperative analgesia
7. Nitrous oxide (and to a lesser extent volatiles)
When would you use A to E vs. CPR & ALS?
The Crisis
- Alive (breathing and have a pulse) = ABCDE
- Dead (no pulse/no breathing) = CPR and ALS protocol
What is the adrenaline dose in a cardiac arrest vs. Anaphylaxis?
How to reverse Fentanyl?
How to reverse Midazolam?
- Reverse Fentanyl with Naloxone
- Reverse Midazolam with Flumazenil
What are the STOP BANG questions for OSA?
How is it confirmed?
- Confirm OSA diagnosis with Sleep studies & Apneoic: Hypopnia Index
What are the consequences of aspiration of gastric contents?
- How to prevent? (3)
- Aspiration = pneumonia (infection) & chemical pneumonitis
- PPI, Anti-emetic (metoclopramide to increase gastric emptying), sodium citrate (neutralizes stomach acid – also used pregnant ladies)
Outline the 5 Steps in Rapid Sequence Intubation?
Rapid Sequence Induction
1 - Preoxygenate until ETO2 (end tidal) >70-80% = Denitrogenate RBCs
2 - Induction agents: Propofol, thiopental, ketamine
3 - Fast-onset muscle relaxant: Suxamethonium chloride (45seconds)
- Polarizing: Rocu
- Non-polarizing (mimics Ach on nicotinic receptors): Sux
5 - Cricoid pressure?
What test other than LFTs should you always order in a patient with suspected obstructive jaundice?
Always do coags because if gallstone obstructing flow of bile into gut then can’t absorb Vit K needed for clotting factors & clotting goes off quickly
2 Complications of Atelectasis & Mx?
Complications of Atelectasis
1. Respiratory failure
2. pPneumonia
**Mx of Atelectasis **
1. Up & out of bed
2. Reduce opioids/Call APS to assist
3. Incentive spirometry
4. On call physio
5. ICU?
6. Repeat blood gas
Seizures & Status Epilepticus
- Definition?
- Causes?
- Early complications?
- Late complications?
- SE Mx?
- Definitions: excitatory state (GABA down and Glutamate up), SE = 5mins (but start to decompensate at 30mins)
- Causes: Tumour, bleeds, abscess, epilepsy, eclampsia, hypoglycaemia, hyponatraemia etc.
- Early complications: trauma, airway compromise = hypoxia
- Late complications: aspiration, rhabdomyolysis (AKI, acidemia, multi-organ failure)
- SE mx: Airway = roll onto side + O2 non-rebreather, NPT (rare)
What is the timeframe for acute vs. chronic pain? Why?
- What are the 3 afferent ascending tracts? Why do we have 3?
Acute vs. Chronic >3months – physiological tissue healing
Afferent ascending tracts – spinothalamic, Dorsal column, Posteromedial = spinolimbic - purpose of having 3 ascending tracts = need info in parallel not series
What is the Gate Theory of Pain?
The Gate Control Theory of Pain is a mechanism, in the spinal cord, in which pain signals can be sent up to the brain to be processed to accentuate the possible perceived pain, or attenuate it at the spinal cord itself. The ‘gate’ is the mechanism where pain signals can be let through or restricted.
What are the different options for the treatment of pain?
