ITE KEY WORDS Flashcards
What is a Bland-Altman Plot?
- A method of data plotting used in analyzing the agreement between two different assays.
- Bland–Altman plots are extensively used to evaluate the agreement among two different instruments or two measurements techniques. Bland–Altman plots allow identification of any systematic difference between the measurements (i.e., fixed bias) or possible outliers.
Femoral Nerve Block Anatomy
Muscles innervated
Cutaneous Innervation
What Distribution is missed?
-
Relevant Anatomy
- Femoral nerve (posterior divisions of L2-4) is formed in the psoas major muscle, runs between psoas and iliacus muscles and enters the thigh under the inguinal ligament lateral to the femoral artery, at which point it divides into multiple terminal branches (usually classified as anterior [mostly cutaneous] and posterior [mostly motor]).
- Landmarks and Surrounding Structures: Important landmarks include the femoral crease, ASIS, pubic tubercle, femoral artery (palpable) and veins (not palpable), both located medially.
- Cutaneous Innervation: The femoral nerve blocks the anterior thigh, as well as the medial lower leg (from the saphenous nerve). Note that it misses a portion of the medial thigh innervated by the obturator nerve (which also innervates the medially-located obturator externus, adductors [brevis, longus, and magnus], and gracilis muscles).
- Muscular Innervation: Major muscles supplied by the femoral nerve include the anterior compartment muscles (quadriceps femoris, sartorius, and pectineus muscles), as well as the more proximal iliacus and psoas major muscles.
- Distributions Missed: Medial thigh (obturator nerve)
Neuromuscular blockade and primary hyperparathyroidims
- Hyperparathyroidism is a common cause of hypercalcemia and the effects of calcium at the neuromuscular junction may cause pre-existing muscle weakness. However, this response is unpredictable and though it might seem that the pre-existing muscle weakness associated with hyperparathyroidism would reduce neuromuscular blocker requirements, it has been suggested that hypercalcemia associated with primary HPT may antagonize the effects of non-depolarizing muscle relaxants, making patients more resitant to blockade.
Treatment of Prolonged QT
- May occur with (Jervell and Lange-Nielsen syndrome) or without (Romano-Ward syndrome) deafness. Presents as lightheadedness, syncope, torsades, and cardiac arrest.
- Immediate Treatment with Magnesium Sulfate
- Acute management is based on intravenous magnesium, replacement of potassium and calcium if indicated. Avoid amiodarone in these patients as it may worsen the disease.
- Long term therapy is usually based on beta blockade,
Aspiration Management of LMA
- Initial steps for management of suspected or confirmed pulmonary aspiration of gastric contents in patients with a LMA include
- increasing FiO2 to 100%
- deepening anesthesia
- placing the patient in a head-down position.
- Suctioning should usually be performed and the severity of aspiration assessed using fiberoptic bronchoscopy. Additional measures such as intubating should be based on clinical judgment.
Caudal: Systemic Toxicity
- The incidence of local anesthetic-induced seizures following caudal epidural block is higher than following lumbar or thoracic approaches.
- The relative risk of local anesthetic toxicity follows this order: caudal > brachial plexus block > lumbar or thoracic epidural block.
- Elevation of heart rate by more than 10 beats per minute or an increase in systolic blood pressure of more than 15 mm Hg after injection of epinephrine-containing local anesthetic is suggestive of intravascular injection.
Identify the following block and structures
- Relaxation of the anal sphincter following local anesthetic injection may predict the success for a caudal block.
- This is particularly useful in children because most caudal blocks are performed while the child is anesthetized, and it is not possible to assess the effectiveness of the block by testing for sensory analgesia levels.
- One study demonstrated that the presence of a lax anal sphincter at the termination of surgery correlated with the reduced need to administer opioids perioperatively.
ERAS Protocol
Fluid therapy for traumatic brain injury
The choice of fluid should fulfill this utmost goal by augmenting oxygen delivery to the brain. Non-blood fluid, such as crystalloid and colloid, may help to treat hypotension and increase cerebral perfusion pressure (CPP), thus increase cerebral blood flow (CBF); however, it does not increase blood hemoglobin concentration and may actually decrease blood oxygen content due to hemodilution. Hypotonic, low sodium and dextrose-containing fluids should be avoided. 0.9% normal saline (NS) or even 3% NS should be considered if a crystalloid is chosen. The use of albumin in trauma victims is controversial. Most trauma centers choose not to use it. Mannitol is often adopted to decrease brain water and augment intravascular volume in patients with increased intracranial pressure. Red blood cell transfusion not only increases intravascular volume and facilitate CPP management but also augment blood oxygen content via the increase in hemoglobin.
Post op nausea Treatment
1) 5-HT3 receptor antagonist (e.g., ondansetron): commonly used in the perioperative management of PONV. Better at preventing vomiting than nausea. The recommended dose for ondansetron is 4mg at the end of the surgery. Do not re-dose unless more than 6 hours have elapsed since the last dose was administered, including in the immediate post-operative period. An adverse effect is QTc prolongation.
2) NK-1 receptor antagonist (e.g., aprepitant): more effective than ondansetron. Recommended to give prior to the start of surgery.
3) Corticosteroids (e.g., dexamethasone): recommended dosing is 4 mg at the beginning of the surgery due to long onset time.
4) Dopamine-2 receptor antagonist (e.g., droperidol, metoclopramide, Prochlorperazine): droperidol is effective as an anti-emetic. Recommended dosing is 0.625 to 1.25 mg at the end of surgery. Metoclopramide is considered a weak anti-emetic. The effective dose for metoclopramide is 25 to 50 mg. Metoclopramide 10mg is not recommended for PONV. Also, metoclopramide is not recommended as an antiemetic for patients who have received prophylactic ondansetron intraoperatively.
5) Anti-cholinergics (e.g. scopolamine patch): need to apply prior to going back to the operating room due to its 2 to 4 hour onset time. Can cause visual changes, dry mouth, and dizziness.
Therapeutic Hypothermia: Electrolyte Abnormalities
Type 1 vs Type 2 Alveoli
Type 1: Small, involved in gas exchange
Type 2: Produce surfactant
Brugada Syndrome Anesthetic Considerations
- Brugada syndrome is a rare autosomal dominant disease & is associated with sudden cardiac death from ventricular fibrillation or tachycardia (VT/VF), especially in Southeast Asian males
Anesthetic Considerations
Potential for hemodynamic collapse due to VT & VF
Avoid exacerbating factors of Brugada (ST Elevation):
Parasympathetic nervous system stimulation (increase in vagal tone)
Medications
Avoid BB, alpha agonists, neostigmine
Avoid class Ia antiarrhythmic (procainamide)
Electrolyte abnormalities: ↑↓K, ↑Ca
Fever
Considerations of AICD if in situ (only known treatment)
Preparations for treating Brugada Exacerbations or cardiac arrest:
All patients without AICD need defibrillator & pads in OR
Atropine, Ephedrine, Isoproterenol
Resuscitation drugs should be available
Typical ECG findings
Characteristic findings are RBBB & ST elevation in V1-V3
Pathophysiology of delayed hemolytic transfusion reaction
- Delayed hemolytic transfusion reactions (DHTRs) occur in patients who have received transfusions in the past. These patients may have very low antibody titers that are undetectable on pretransfusion testing, so that seemingly compatible units of red blood cells (RBCs) are transfused. Exposure to antigen-positive RBCs then provokes an anamnestic response and increased synthesis of the corresponding antibody. After several days, the antibody titer becomes high enough to hemolyze transfused RBCs. The frequency of DHTRs is estimated to be approximately 1 case per 5400 red cell units transfused.
DHTRs are a potentially life-threatening complication of sickle-cell disease (SCD) treatment.
Diffusion Hypoxia Prevention with N2O Use
Diffusion Hypoxia has proven to be avoided by administration of oxygen for 10 minutes from cessation of nitrous oxide anaesthesia.
Cerebral palsy anesthetic considerations and managment
Background
A disorder of movement & posture due to a static encephalopathy
Huge spectrum of presentation: almost asymptomatic to completely dependent
Caused by a cerebral insult in the immature brain that occurred prenatally, perinatally, or during infancy
The motor deficit may manifest as:
Hypotonia
Spasticity
Extrapyramidal features such as choreoathetoid/dystonic movements or ataxia
Considerations
↓ C-spine mobility & possible difficult intubation
Aspiration risk (GERD/↓lower esophageal sphincter tone)
Pulmonary:
Recurrent aspiration & pulmonary impairment
Scoliosis & ↑ bleeding risk during scoliosis surgery
Rule out pulmonary HTN/RV failure
CNS:
Developmental delay/lack of cooperation
Seizure d/o
Hydrocephalus
Altered response to anesthetics:
↓ MAC of volatiles & longer emergence
↑ sensitivity to muscle relaxants
Volatiles & succinylcholine NOT contraindicated
Difficult IV access, monitoring, & positioning due to contractures
Ex-premature conditions
↑ risk of hypothermia
Needlestick infectious risk and management
HIV
HBV
HCV
Hepatitis B prophylaxis Current CDC guidelines call for the administration of hepatitis B immune globulin (HBIG) and/or hepatitis B vaccine. While the efficacy of the combination has not been evaluated in the needlestick injury setting, it has been shown to be the most efficacious approach in the perinatal setting. The approach has no contraindications during pregnancy and lactation.
Hepatitis C prophylaxis CDC guidelines acknowledge that there is no active post-exposure prophylaxis for HCV. There is some evidence that treatment with interferon alfa-2b may be beneficial preventing chronic hepatitis.
HIV prophylaxis CDC guidelines generally recommend a post-exposure prophylaxis protocol with 3 or more antiviral drugs, when it is known that the donor was HIV positive; however, when the viral load was low and none of the above noted risk factors are met, the CDC protocol utilizes 2 antiviral drugs
Fontant Circulation
The order for repair of hypoplastic left heart syndrome is “Not Gonna Fly”
Background
Fontan is a palliative procedure for patients with functional univentricular physiology
Selection criteria for performance of Fontan are: adequately sized pulmonary arteries; low PVR; good LV function & the presence of sinus rhythm
The driving force for blood flow through the pulmonary circulation is the difference between central venous pressure (CVP) & atrial pressure:
There is NO active pumping of blood through the lungs
Cardiac output is essentially completely dependent on pulmonary blood flow
Hypovolemia is tolerated very poorly
Preoperative preparation: Review information from patient’s cardiologist; changes in patient’s exercise tolerance, level of cardiac impairment, details of the patient’s physiology, anatomy, & any residual & sequelae of previous surgeries
Minimize NPO interval, maintain intravascular volume (↓ preload results in ↓ pulmonary blood flow & cardiac output)
Goals
Hemodynamic goals:
Preload: keep full, avoid dehydration
Rate & rhythm: strict normal sinus rhythm
Contractility: maintain
Afterload: maintain
Pulmonary vascular resistance: keep low
Avoid hypercarbia, hypoxemia, acidosis, stress, pain, high intrathoracic pressures
Fluid management:
Guided by CVP or TEE (TEE very useful)
Vascular capacitance is ↑ in the Fontan patient; more fluid may be required than anticipated based on the formula commonly used to calculate fluid requirement
Ventilatory strategy:
Spontaneous ventilation is best as it enhances venous return & pulmonary blood flow
For PPV:
Limit peak inspiratory pressure (<20 cmH2O), use low respiratory rates (<20 bpm), short inspiratory times, avoid excessive positive end-expiratory pressure, moderately elevated tidal volumes (10–15 mL/kg), ensure adequate intravascular volume
Postoperative concerns:
Maintaining volume status, acid-base balance, & cardiac output are essential in the postoperative period; ensure adequate hydration & aggressively manage low cardiac output with intravenous hydration & inotropes
Adequate analgesia improves pulmonary mechanics & oxygenation; enhanced vigilance is required to avoid the effects of hypercapnia secondary to opioids
Treat postoperative nausea & vomiting to permit adequate hydration, prevent dehydration & electrolyte loss, & allow the patient to resume their medication regimen
The order for repair of hypoplastic left heart syndrome is “Not Gonna Fly”: Norwood, Glenn, Fontan.
