Surgical Complications Flashcards
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
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)
What is the differential for prolonged PTT?
Acquired FVIII inhibitors Antiphospholipid syndrome Hemophilia A / B Heparin Von Willebrand disease
Why do we ask about history of bleeding after minor trauma/procedures?
Predisposition to bleeding risk!
Why do we ask about family history of bleeding?
Suggests inherited bleeding disorder
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
What is difference between primary and secondary hemostasis disorders?
Primary: platelets
Secondary: factor abnormalities
What is coagulopathy?
Impairment of body’s ability to clot blood
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
How does renal failure cause coagulopathy?
Uremic toxins in blood –> platelet dysfunction
How do we manage coagulopathy in setting of renal failure?
Desmopressin (acutely) and/or
HD (definitively)
How does liver disease cause coagulopathy?
Synthetic liver function decreased and thrombocytopenia: prolonged PT and INR
Why do surgical bleeds occur?
Inadequate hemostasis
What are risk factors for coagulopathy?
Copious IV fluids/transfusions Hypothermia Metabolic acidosis Liver/Kidney dsiease DIC Fam history of bleeding Anticoagulants
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
What’s the most common cause of thrombocytopenia?
Alcohol use
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
What is mechanism of DIC?
Clotting cascade activation –> deficiency of factors –> abnormal bleeding
What is the primary treatment of DIC?
Treat underlying cause
What is physiological fibrinolysis?
Generation of fibrin: occurs when plasmin binds to it: breaks down clots to limit extent of clot formation
What can abnormal activation of fibrinolytic pathway cause?
Bleeding and excess plasmin which consumes clotting factors –> more bleeding
What is the most important diagnostic modality for coagulopathy?
Clinical history
What is the treatment of hepatic coagulopathy?
FFP
What is the reversal for heparin? warfarin?
Heparin: Protamine sulfate
Warfarin: FFP and Vit K, or prothrombin complex concentrates
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)?
- Prerenal
- Intrinsic
- 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?
- Rule out obstructed Foley
- Stop nephrotoxic drugs
- 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?
> 4
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?
- 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?
- Heparin alone
- tPA
- Endovascular clot aspiration
- 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?
- Heparin/LMWH for first 5 days
- 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
