Diagnosis
History and Physical
Comments
Pneumonia
Fever, dyspnea, dullness to percussion, prolonged intubation, aspiration, PPI use → ↑gastric pH leading to ↑gram-negative bacteria growth in stomach
Most common cause of nosocomial mortality, aspiration (right lower lobe if patient is upright, right upper lobe if patient is supine)
Pulmonary embolism
Recent travel (e.g., long airplane or car ride), immobilization, recent surgery, trauma or central line (within 3 months), cancer, history of DVT or PE, smoking, CVA, CHF, COPD, look for Virchow’s triad (see below)
Usually from DVT in pelvic or leg veins
Myocardial infarction
H/o MI, diabetes, CHF
Surgery creates proinflammatory state, leads to plaque rupture and thrombosis of coronary artery
Pneumothorax
Diminished/absent breath sounds, associated with central line placement (US-guided line placement lowers risk)
Air leak in pleura allows equalization of negative pleural pressure with ambient pressure
Cardiogenic pulmonary edema
Rales, JVD, S3, bilateral leg swelling
PCWP > 18 mmHg
Noncardiogenic pulmonary edema
Sepsis, massive transfusion, trauma, pancreatitis; no rales, S3, or JVD
PaO2/FiO2 < 200, hypoxemia with respiratory alkalosis; bilateral infiltrates on CXR, includes ARDS
Anxiety
Must rule out other causes first
Psychogenic
Bleeding
Hypotension, tachycardia, decreased urine output
Most often in the first hours after surgery
What Is the Most Likely Diagnosis?
The differential diagnosis for acute shortness of breath with hypoxia is extensive. The primary etiologies in the postoperative period are shown above. Pneumonia and cardiogenic pulmonary edema are high on the list; however, the absence of physical exam evidence of fluid overload (JVD, rales, or crackles) points against cardiogenic pulmonary edema. Similarly a normal lung exam and normal CXR make pneumonia, atelectasis, and noncardiogenic pulmonary edema very unlikely. The combination of hypoxia, respiratory alkalosis, tachycardia, and a wide A-a gradient points to a pulmonary embolus (PE). This is further reinforced by a normal CXR and ECG. Finally, the unilateral leg swelling suggests that the source of PE is a leg deep vein thrombosis (DVT). This phenomenon is known as a venous thromboembolism (VTE).
History and Physical Exam
What Is Virchow’s Triad? Which Part of the Triad Can Be Invoked in the Patient?
At least one of Virchow’s triad is generally present for a venous thromboembolic event (VTE). The triad includes stasis, endothelial injury, and a hypercoagulable state. The patient described above has two of the triad: cancer, which is a cause of hypercoagulability, and stasis from being immobile during and after the operation. Surgery, just like other types of trauma, also induces a hypercoagulable (prothrombotic) state.
Stasis occurs during prolonged bed rest such as after an injury, a surgery, or a long plane flight or car ride. Walking causes the leg muscles to act as a pump to move blood back to the heart. In the immobile patient, venous blood will tend to collect in the legs, leading to stasis. Hypercoagulable states can be congenital or acquired. Injury to the vein can occur after a trauma (leg fracture) or an iatrogenicity (venous cannulation with a central line).
What are The Risk Factors for VTE and Their Mechanism?
Stasis |
Immobilization |
Endothelial injury |
Surgery |
Trauma |
Central line within last 3 months |
History of DVT or PE |
Hypercoagulability |
Smoking |
Oral contraceptive pills |
History of DVT or PE |
Inherited disorders (e.g., factor V Leiden, protein C deficiency) |
What Is the Wells Score for PE?
The Wells score is calculated by adding the points associated with clinical findings in Table 40.1. A score of > 4 points indicates a likely PE, whereas a score ≤ 4 points indicates a low likelihood of PE.
Table 40.1
Wells score
Finding | Points |
|---|---|
Signs and symptoms of DVT | 3 |
PE most likely diagnosis | 3 |
HR > 100 | 1.5 |
Prior DVT or PE | 1.5 |
Immobilization within last 4 weeks | 1.5 |
Malignancy within last 6 months | 1 |
Hemoptysis | 1 |
What Are the Main Clinical Findings Associated with a DVT?
The main clinical findings are leg swelling, calf pain, warmth of leg, mild redness of calf, and calf tenderness.
Watch Out
The left leg is 2× more commonly affected by DVT because the left iliac vein is often compressed by the right iliac artery. This phenomenon is known as May-Thurner syndrome.
What Is Homans’ Sign? Why Has It Fallen Out of Favor?
Homans’ sign is a physical exam finding that was classically associated with DVT. The sign is considered positive when you can elicit calf pain with dorsiflexion of the foot. It is no longer used routinely because a positive sign does not likely indicate a DVT. It has a very low sensitivity of 30 %, which limits its clinical utility.
The 5 Classic Causes of Postoperative Fever may be Remembered as the 5 Ws of Postoperative Fever
W | Etiology | Post-op day |
|---|---|---|
Wind | Atelectasis | 1–2 |
Water | Urinary tract infection | After 3 |
Wound | Wound infection | After 5 |
Walking | DVT/thrombophlebitis | 7–10 |
Wonder drugs | Drug fever (e.g., antibiotics) | Anytime |
