Principles of Surgery Flashcards
Ejection fraction considered prohibitively risky in a noncardiac pt
under 35%
Risks considered by Goldman’s index of cardiac risk
jugular venous distention (evidence of congestive heart failure), recent MI (within
6 months), either premature ventricular contractions (5 or more per minute) or a rhythm other than sinus, age over 70, emergency surgery, and either aortic valvular stenosis, poor medical condition, or surgery within the chest or abdomen
worst single finding predicting high cardiac risk
Jugular venous distention
second worst predictor of cardiac complications
Recent MI
Most common cause of increased pulmonary risk, and what happens to lungs
Smoking. The problem is compromised ventilation.
Hepatic predictors of mortality
bilirubin (which reflects hepatocellular function), serum albumin, prothrombin time, ascites, and encephalopathy
Definition of severe nutritional depletion
Loss of 20% body weight over a couple of months, albumin below 3, anergy to skin antigens, or transferrin less than 200
What must you do for a pt in a diabetic coma before surgery
Rehydration, return of urinary output, and at least partial correction of the acidosis and hyperglycemia
What caused fever when fever develops shortly after the onset of the anesthetic (halothane or succinylcholine). Temperature exceeds 104°F. Metabolic acidosis and hypercalcemia also occur.
Malignant hyperthermia
How to treat malignant hyperthermia
IV dantrolene, 100% oxygen, correction of the acidosis, and cooling blankets. Watch for development of myoglobinuria.
What may have caused postoperative fever seen within 30–45 minutes of invasive procedures (instrumentation of the urinary tract is a classic example), and there are chills and temperature spike to or exceeding 104°F
Bacteremia
What should you do about a pt w/ postoperative bacteremia
Do blood cultures times
three, start empiric antibiotics.
Postoperative fever in the normal range (101-103) causes in sequential order
atelectasis, pneumonia, urinary tract infection, deep venous thrombophlebitis, wound infection, or deep abscesses.
most common source of post-op fever on the first PO day.
Stele tases
This will happen in about 3 days if atelectasis is not resolved. Fever will persist. Chest x-ray will show infiltrates.
Pneumonia
typically produces fever starting on PO day 3. Work up with urinalysis, urinary cultures. Treat with appropriate antibiotics
UTI
typically produces fever starting on PO day 5 or thereabouts. Doppler studies of deep leg and pelvic veins is the best diagnostic modality (physical exam is worthless). Anticoagulate with heparin.
Deep vein thrombophlebitis
Typically begins to produce fever on PO day 7. Physical exam will show erythema, warmth, and tenderness.
Wound infection
Tx wound infection
Treat with antibiotics if there is only cellulitis; open and drain the wound if an abscess is present. When these two cannot be easily distinguished clinically, sonogram is diagnostic
These start producing fever around PO days 10–15. CT scan of the appropriate body cavity is diagnostic. Percutaneous radiologically guided drainage is therapeutic.
Deep abscesses (like subphrenic, pelvic, or subhepatic)
The W’s of postop fever (according to OME)
Wonder drugs Wind Water Walking Wound Wonder drugs
Most reliable test for postop MI
Troponin
What to do for someone who is having a perioperative MI
emergency angioplasty and coronary stent
When will PE happen postop
Day 7 in elderly/immobilized patients
Suspect this in a pt w/ chest pain that is pleuritic, sudden onset, accompanied by SOB. The patient is anxious, diaphoretic, and tachycardic, with prominent distended veins in the neck and forehead. Arterial blood gases show hypoxemia and hypocapnia.
PE
Standard diagnostic test for postop PE
spiral CT, usually w/ contrast
Tx for postop PE
start treatment with heparinization. Add an inferior vena cava filter (Greenfield) if PEs recur while anticoagulated or if anticoagulation is contraindicated.
First thing to suspect when a postop patient gets confused and disoriented
hypoxia. may be secondary to sepsis. check blood gasses, give respiratory support
Centerpiece of therapy for ARDS
PEEP, not using excessive volume. Seek and correct a source of sepsis.
Timing of Delirium Tremens
POD 2 or 3
Tx for delirium tremens
IV benzodiazepines
Suspect this as the source of coma in a postop cirrhotic patient w/ bleeding esophageal varices who got a portocaval shunt
Ammonium intoxication
When should you catheterize a postop patient if no voiding has occurred?
6 hours postop, do just an in-and-out catheter. At the second or third time, do an indwelling foley catheter
3 tests you can do to determine if a patient with low urine output is dehydrated or in renal failure
Fluid challenge (500 mL IV fluid, in dehydrated pts it will temporarily increase urine output, in renal failure it won't) Urinary sodium (In dehydrated pts it'll be less than 10-20 mEq/L, will exceed 40 mEq/L in renal failure) Fractional excretion of sodium (in renal failure, will exceed 1)
Consider this when the paralytic ileus of a postop patient doesn’t resolve after 5-7 days. How to diagnose?
Early mechanical bowel obstruction. do a CT scan, you’ll see dilated bowel proximal to obstruction, and collapsed bowel distal to obstruction.
Ogilvie syndrome
“Paralytic ileus of the colon”; It does not follow abdominal surgery, but classically is seen in elderly, sedentary patients (Alzheimer, nursing home) who have become further immobilized owing to surgery elsewhere (broken hip, prostatic surgery). They develop large abdominal distention (tense but not tender), and x-rays show massively dilated colon.
How to treat ogilvie syndrome
After fluid and electrolyte correction, it is imperative that mechanical obstruction be ruled out radiologically or by endoscopy before giving IV NEOSTIGMINE to restore colonic motility. A long rectal tube is also
commonly used.
Consider this in a postop patient whose wound looks intact, but large amounts of pink, “salmon colored” fluid are noted to be soaking the dressings (it is peritoneal fluid).
Also, what should you do?
Wound dihiscence. The wound has to be taped securely, the abdomen bound, and mobilization and coughing done with great care, while arrangements are made for prompt reoperation to prevent evisceration now or ventral hernia later on.
What should you do if a patient eviscerates?
The patient must be kept in bed, and the bowel be covered with large sterile dressings soaked with warm saline. Emergency abdominal closure is required.
Nature will heal a GI fistula, unless what conditions are present?
FETID: foreign body, epithelialization, tumor, infection, irradiated tissue, inflammatory bowel disease, or distal obstruction (the “F.E.T.I.D.” mnemonic) to prevent it. Steroids will also prevent healing.
Suspect in a young woman with bleeding after minor surgical procedure or history of excessive menses
Von Willebrand disease
Suspect in a young woman with malar rash, arthritis, photosensitivity, renal/cardiac symptoms, fevers, malaise, and recurrent pregnancy loss
SLE (think selena gomez, with a rash on her face, feeling shitty in the bright stage lights. she eventually got a kidney transplant)
Suspect this in young children bleeding into their joints. Alternatively, a kid who bleeds excessively after minor trauma
Hemophilia A or B (clinically indistinguishable)
How does von Willebrand deficiency cause bleeding?
When vessels get damaged, the subendothelial collagen can attach to von Willebrand factor; VWF then binds platelets, which form a platelet plug. Deficiency leaves the platelet plug unformed. VWF is also a cofactor for Factor VIII, so it can prolong PTT as well.
The only component of the clotting cascade not completely formed in the liver; will stay stable in liver failure
Factor VIII
List the Vitamin K dependent clotting factors (6)
Factors II, VII, IX, and X, and protein C and S
Cutoff value for thrombocytopenia
> 150,000
Mechanism of DIC
Initial coagulopathy caused by extensive activation of the clotting cascade, usually by the release of endothelial tissue factor. Uncontrolled clotting and fibrinolysis lead to a deficiency in clotting factors resulting in abnormal bleeding. Patients may form diffuse microthrombi in addition to having abnormal bleeding, causing infarcts.
3 most common causes of DIC
DIC:
Delivery,
Infection,
Cancer
Primary treatment of DIC
treat the underlying cause
Primary vs Secondary Hyperfibrinolysis
Primary hyperfibrinolysis results from an increase in circulating tissue plasminogen activator (tPA).
Secondary fibrinolysis is a response to a systemic hypercoagulable state and increased amounts of fibrin. This most often occurs during a systemic inflammatory state, such as sepsis or DIC.
What does INR actually measure, and what drug can it monitor?
INR measures the extrinsic and common coagulation pathways, specifically Factor I (fibrinogen), II (prothrombin), V, VII, and X.
It can be used to monitor Warfarin
What does PTT actually measure, and what drug can it monitor?
PTT measures the intrinsic and common coagulation pathways, specifically Factor I (fibrinogen), II (prothrombin), V, VIII, IX, X, XI, XII. It can be used to monitor Heparin.
What does aspirin do
Irreversibly inhibits platelet cyclooxygenase enzymes, which results in decreased formation of PGE2 and thromboxane A2
what does clopidogrel do
Blocks ADP receptors to suppress fibrinogen binding to platelets and thus inhibits platelet adhesion
what does heparin do, and how do you reverse it
Activates antithrombin III; activated antithrombin III inactivates thrombin and
factor Xa. Reverse with protamine sulfate.
What does LMWH do, and how do you reverse it
Binds to factor Xa, prevents clot formation. Reverse with protamine sulfate.
what does warfarin do, and how do you reverse it
Inhibits vitamin K epoxide reductase, an enzyme required for the production of factors II, VII, IX, and X. Reverse with fresh frozen plasma (FFP) for fast results, or Vitamin K for slower results.
Most Important Preoperative Test to Identify a Patient at Risk for Bleeding During Surgery?
Clinical History, specifically a history of excessive bleeding after minor procedures.
How to treat postop bleeding due to renal failure? (2)
Desmopressin can help transiently, as it promotes the production of VWF. Dialysis is definitive.
How to treat postop bleeding due to liver failure? (4)
Fresh Frozen Plasma (FFP), cryoprecipitate, coagulation factors, platelet transfusion
The most common reaction to blood transfusion, when does it happen, and what is it caused by? How to treat?
Febrile nonhemolytic, happens minutes to hours after transfusion, caused by cytokines from donor WBC. Self-limited (acetaminophen can help)
Reaction to blood in first 24 hours; destruction of donor RBC by preformed host antibody (ABO incompatibility). How to treat?
Acute hemolytic. Stop transfusion, IV fluids to induce diuresis
1-14 days after blood transfusion, reaction happens. Name, cause, and treatment?
Delayed hemolytic. Cuased by Rh factor antibodies destroying donor RBC. Self-limited.
Rapid and sudden drastic reaction to blood transfusion; patient is in shock. Name, cause, treatment?
Anaphylactic reaction. Anti-IgA antibody, occurs in pts w/ selective IgA deficiency. Stop transfusion, epinephrine, intubate, fluids.
Allergic/urticarial rxn to blood transfusion. When will it occur, why does it happen, and how do you treat?
Minutes to hours after transfusion, host has allergic rxn to donor plasma, treat with Diphenhydramine (Benadryl)
Leading Cause of Transfusion- Related Fatalities, and how to treat?
Transfusion-related acute lung injury (TRALI), characterized by pulmonary edema. Tx w/ IV fluids, vasopressors, respiratory support.
