Surgical Complications Flashcards by Catherine Parkhurst

What’s in the differential for bleeding in the post-op setting?

Surgical bleeding: bleed from artery/vein in surgery
Meds
Inherited coag d/o
Liver disease: reduced clotting factor production
Renal failure: uremia impairs platelet function
DIC

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What is the bloody vicious cycle or the lethal triad of death?

Trauma
Large volume of room temp IV fluids
Long operations
(More common in those with sign. bleeding)

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What is the differential for prolonged PTT?

Acquired FVIII inhibitors
Antiphospholipid syndrome
Hemophilia A / B
Heparin
Von Willebrand disease

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Why do we ask about history of bleeding after minor trauma/procedures?

Predisposition to bleeding risk!

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Why do we ask about family history of bleeding?

Suggests inherited bleeding disorder

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What medical conditions are risk factors for bleeding?

Liver disease (clotting factors deficient)
Kidney disease (uremia inhibits platelets)
Malabsorption syndrome (vit K def)
Cardiac dz due to the meds

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What is difference between primary and secondary hemostasis disorders?

Primary: platelets
Secondary: factor abnormalities

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What is coagulopathy?

Impairment of body’s ability to clot blood

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What is a medical vs. surgical post-op beed?

Surgical: bleeding that can be corrected w/ surgery (bleeding from focal artery/vein that was inadequately ligated or sutured during initial surgery)
Medical: diffuse bleeding caused by underlying coagulopathy

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How does renal failure cause coagulopathy?

Uremic toxins in blood –> platelet dysfunction

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How do we manage coagulopathy in setting of renal failure?

Desmopressin (acutely) and/or

HD (definitively)

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How does liver disease cause coagulopathy?

Synthetic liver function decreased and thrombocytopenia: prolonged PT and INR

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Why do surgical bleeds occur?

Inadequate hemostasis

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What are risk factors for coagulopathy?

Copious IV fluids/transfusions
Hypothermia
Metabolic acidosis
Liver/Kidney dsiease
DIC
Fam history of bleeding
Anticoagulants

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What to think: coagulopathy in patient who recently started heparin?

HIT: platelets drop > 50% because of Ab formed by heparin + platelet factor 4 that destroy platelets

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What’s the most common cause of thrombocytopenia?

Alcohol use

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What are the 3 main causes to think about for DIC?

Delivery (pregnancy): tissue thromboplastin in amniotic fluid activates coag cascade
Infection: sepsis causes endothelial cells to make tissue factor
Cancer: Auer rods in AML activate coagulation cascade

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What is mechanism of DIC?

Clotting cascade activation –> deficiency of factors –> abnormal bleeding

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What is the primary treatment of DIC?

Treat underlying cause

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What is physiological fibrinolysis?

Generation of fibrin: occurs when plasmin binds to it: breaks down clots to limit extent of clot formation

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What can abnormal activation of fibrinolytic pathway cause?

Bleeding and excess plasmin which consumes clotting factors –> more bleeding

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What is the most important diagnostic modality for coagulopathy?

Clinical history

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What is the treatment of hepatic coagulopathy?

FFP

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What is the reversal for heparin? warfarin?

Heparin: Protamine sulfate
Warfarin: FFP and Vit K, or prothrombin complex concentrates

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For most elective procedures, what level of platelets is sufficient?

> 50,000

At what point should re-exploration be considered for a patient who is bleeding post-op?

Only in surgical bleed: medical bleed must be deemed unlikely and patient continues to actively bleed

What is the leading cause of transfusion-related fatalities?

Transfusion-Related acute lung injury (TRALI): donor Ab attack recipient's WBC - aggregates in lungs and releases inflammatory mediators

How do we treat TRALI?

IV fluids Vasopressors Respiratory support

How long before surgery should we stop aspirin? Clopidogrel?

Aspirin: 4 days Clopidogrel: 7-10days

How long after warfarin is stopped will INR fall below 2.0? To normalize?

< 2.0: 2-3 days | Normalize: 4-6 days

What's the differential diagnosis for AKI in the post-op setting (categories)?

1. Prerenal 2. Intrinsic 3. postrenal

What's the pre renal cause of AKI post-op?

Hypovolemia or decreased CO causing hypo perfusion of kidney

What's the intrinsic renal cause of AKI post-op?

ATN or interstitial nephritis: prolonged ischemia of the kidney or toxins leading to parenchymal injury

What's the postrenal renal cause of AKI post-op?

Obstruction: BPH, prostate cancer, nephrolithiasis: all cause increased nephron tubular pressure

What's the most common cause of decreased urine output post-op?

Hypovolemia/dehydration decreasing perfusion to kidney

What thins do we look for on the operative and anesthetic record in decreased urine output?

- Events that could cause! - Blood loss - Complications - Anticoagulants

What is the most common presentation of AKI?

Prerenal azotemia: rise in BUN and creatinine

What is the earliest sign of AKI?

oliguria

What are the standards of oliguria vs. anuria?

Oliguria: adult: 0.5-1.0 mL/kg/hour Anuria: <50-100 mL per 24 hours

What are the most common nephrotoxic meds?

``` Contrast Aminoglycosides Amphoterocin Cispatin Cyclosporine NSAIDs ```

Who is at greatest risk for IV-contrast induced AKI?

Patients with pre-existing renal damage!

What can help to prevent contrast-induced renal failure?

N-acetylcysteine Bicarbonate Normal saline hydration

What rise in creatinine defines contrast-induced AKI?

Increase of creatinine of 0.5mL/dl within 48-72 hours

What are the hormones primarily responsible for post-op oliguria?

ADH | Aldosterone

What else can cause increased BUN/Cr ratio?

UGI bleed: high protein absorption Increased urea production (steroid therapy) Low muscle mass (low serum creatinine)

After surgery, what duration of oliguria warrants investigation?

24 hours

What's the best initial test when suspecting AKI?

BUN and Cr: BUN/Cr > 20:1 with history of hypo- perfusion

What other tests, besides BUN and Cr, can help workup AKI?

UA Urine Na FENa Urine osmolality

What imaging is useful in the work-up of oliguria?

- US to look for obstruction: bladder, kidneys, ureters | - Doppler US for renal perfusion

When encountering low urine output, what 3 simple things must be done first?

1. Rule out obstructed Foley 2. Stop nephrotoxic drugs 3. Do a fluid challenge

What is a fluid challenge?

Give an oliguric patient a bolus of NS (0.5-1L) over 30 minutes to see if they increase urine output

What should be done for an oliguric patient if they're suspected of having a post-renal obstruction?

Give a Foley catheter to relieve it

What are the indications for urgent/emergent dialysis?

``` AEIOU Acidosis Electrolyte abnormalities (Hyperkalemia) Intoxication (ethylene glycol) Overload (fluid) Ureimia ```

What's in the differential for post-op SOB?

``` Pneumonia PE MI Pneumothorax Cardiogenic/non pulmonary edema Anxiety Bleeding ```

What is Virchow's triad?

Stasis Endothelial injury Hypercoaguable state

What is the Wells' score cutoff for high likelihood of PE?

Which leg is more often affected by DVT and why?

Left: L iliac vein is often compressed by the R iliac artery (May Thurner syndrome)

What signs are associated with PE?

Sudden onset dyspnea, pleuritic chest pain, and/or tachycardia

What are the 5 classic causes of post-op fever?

``` Wind: Atelectasis POD1-2 Water: UTI: POD3+ Wound: infection POD5+ Walking: DVT/thrombophlebitis: POD 7-10 Wonder drugs: drug fever anytime ```

What are the most common acquired causes of hypercoaguability?

``` Advanced age Pregnancy Malignancy OCPs Hormone replacement Smoking Obesity Nephrotic syndrome HIT ```

What can be the cause of cardiogenic pulmonary edema on post-op day 3?

Third spacing: large volume of IV fluids given during surgery return back to the vasculature and poor heart function places you at risk to overwhelm the hert

What are the 3 routes by which a patient develops post-op pneumonia?

Inhalation Aspiration Hematogenous spread

What's the differential of a wide A-a. gradient in the post-op setting?

Atelectasis pneumonia PE

What's the first step in the work-up of a patient suspected of having a PE?

Calculate Wells Score

If there is a high suspicion of DVT, what it is the first step in workup?

1. Heparin immediately to stop clot propagation | 2. CT angiogram

If there is a low suspicion of DVT, what it is the first step in workup?

D-dimer assay because of negative predictive value | - If elevated: CT angiogram

In PE patient, what are most common findings on ABG?

ABG: Acute respiratory. alkalosis, hypoxemia, increased A-a gradient

In PE patient, what are most common findings on CXR?

Normal

In PE patient, what are most common findings on ECG?

Sinus tach

What other labs should be sent in suspected PE?

D-dimer BNP Troponin labs

If CT angiogram is non-diagnostic in suspected PE, what is the next step?

V/Q scan

Why has V/Q scan fallen out of favor for diagnosing PE?

Because a significant percentage of patients with low probability on V/Q scan end up actually having a PE

If a patient is critical ill and cannot be transported for imaging, what bedside options are available for indirect diagnosis of PE?

Echocardiogram can show R heart strain, or doppler US can show venous thrombosis

What is a low risk PE?

No evidence of RV dysfunction or myocardial necrosis

What is a submassive PE?

Evidence of RV dysfunction on echo, or myocardial necrosis (based on NBP or elevated troponin)

What is a massive PE?

Evidence of RV dysfunction on echo, or myocardial necrosis (based on NBP or elevated troponin) PLUS sustained hypotension

What is the initial anticoagulant management of PE?

Heparin or LMWH

If a patient with suspected PE has contraindication to anticoagulation, what to do?

Place IVC filter

What are the treatment options for PE after initial anticoagulation?

1. Heparin alone 2. tPA 3. Endovascular clot aspiration 4. open pulmonary embolectomy

When is tPA used for PE?

Massive PE, should be considered in submissive PE

How do we treat submassive PE?

Heparin/LMWH and consider tpa

How do we treat massive PE?

tPA or pulmonary embolectomy

What is the recommendation for long-term anticoagulation after first time VTE?

1. Heparin/LMWH for first 5 days 2. Start warfarin day 2 to bridge * * Anticoagulate for at least 3 months after VTE, at least 6 months if recurrent or unprovoked

Which anticoagulant to use in patients with VTE and malignancy?

LMWH

Which anticoagulant to use in patients with VTE and history of HIT?

Direct thrombin inhibitors

Surgical Complications Flashcards

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