Preoperative Management of Hypoxic Patients

R1 謝佩芳

Classification of HypoxiaHypoxia

Pathophysiologic Category

Clinical Example

Hypoxic hypoxia

Decreased Pbarom or FiO2

Altitude, O2 equipment error

Alveolar hypoventilation

Drug overdose, COPD exacerbation

Pulmonary diffusion defect

Emphysema, pulmonary fibrosis

V/Q mismatchAsthma, pulmonary emboli

R-->L shuntAtelectasis, cyanotic congenital heart disease

Circulatory hypoxia

Reduced cardiac output

CHF, MI, dehydration

Classification of HypoxiaHypoxia

Pathophysiologic Category

Clinical Example

Hemic hypoxiaReduced Hb content Anemia

Reduced Hb functionCarboxyhemoglobinemia, methemoglobinemia

Demand hypoxia

Increased oxygen consumption

Fever, seizures

Histotoxic hypoxia

Inability of cells to utilize oxygen

Cyanide toxicity

Atelectasis and pulmonary embolism are most likely causes of the

desaturation.

Atelectasis

Preoperative Evaluation for Postoperative Pulmonary Complications

Postoperative Pulmonary Complications (PPC)

• Atelectasis

• Pneumonia

• Respiratory failure

• ARDS

• Pleural effusion

Med Clin N Am 87(2003) 153-173

Med Clin N Am 87(2003) 153-173

Med Clin N Am 87(2003) 153-173

Preoperative Evaluation for Postoperative Pulmonary Complications

Risk Reduction Strategies

Preoperative smoking cessation

Abstinence for at least 8 weeks probably decreases PPC risk

Med Clin N Am 87(2003) 153-173

Preoperative Evaluation for Postoperative Pulmonary Complications

Risk Reduction Strategies

• Perioperative lung expansion maneuvers

- Incentive spirometry

- Chest physical therapydeep breathing exercisepostural drainagepercussion and vibrationcoughsuctioningmobilization Med Clin N Am 87(2003) 153-173

Preoperative Evaluation for Postoperative Pulmonary Complications

Risk Reduction Strategies

• Perioperative lung expansion maneuvers

- Intermittent positive pressure breathing

- CPAP

• Patient education in lung maneuvers initiated preoperatively is more effective in reducing PPC versus education initiated postoperatively

Med Clin N Am 87(2003) 153-173

Preoperative Evaluation for Postoperative Pulmonary Complications

Risk Reduction Strategies

• Postoperative analgesia

• Optimizing pulmonary function in patients with COPD and asthma

• Delaying surgery for patients with acute exacerbations of chronic lung disease or URI.

• No clear role for prophylactic antibiotic use.

Med Clin N Am 87(2003) 153-173

Pulmonary Embolism

Venous Thromboembolism (VTE)

The cornerstone of VTE diagnosis is clinical suspicion.

Because the first manifestation of VTE may be fatal pulmonary embolism (PE), patients with suspected VTE should be anticoagulated until the diagnosis is excluded.

Med Clin N Am 86(2002) 731-748

Diagnosis of VTE

Duplex ultrasonography

Contrast venography or MR venography

Patient with suspected PE:

• Lung ventilation and perfusion scan

• Helical CT

Med Clin N Am 86(2002) 731-748

Prevention of Venous Thromboembolism

Chest 2004; 126:338S-400S

The Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy

Recommendations: Trauma

Factors with increased risk of VTE:• Spinal cord injury• Lower extremity or pelvic fracture• Need for a surgical procedure• Increasing age• femoral venous line insertion or

major venous repais• Prolonged immobility• longer duration of hospital stay

Recommendations: TraumaWe recommend that all trauma patients with at least one risk fector for VTE receive thromboprophylaxis, if possible

In the absence of major contraindication (intracranial bleeding, ongoing and uncontrolled bleeding, uncorrected major coagulopathy, incomplete SCI with suspected or proven perispinal hematoma...), we recommend that clinicians use LMWH prophylaxis starting as soon as it is considered safe to do so.

Recommendations: Trauma

We recommend that mechanical prophylaxis with intermittent pneumatic compression (IPC), or possibly with graduated compression stocking (GCS) alone, be used if LMWH prophylaxis is delayed or if it is currently contraindicated due to active bleeding or a high risk for hemorrhage

Recommendations: Trauma

We recommend DUS screening in patients at high risk for VTE and who have received suboptimal prophylaxis or no prophylaxis

We recommed against the use of inferior vena cava filters (IVCFs) as primary prophylaxis in trauma patients.

Recommendations: Trauma

We recommend the continuation of thromboprophylaxis until hospital discharge, including the period of inpatient rehabilitation.

We suggest continuing prophylaxis after hospital discharge with LMWH or a VKA (target INR, 2.5; INR range, 2.0 to 3.0) in patients with impaired mobility.

As for this patient...Atelectasis

• Perioperative lung expansion maneuvers

Pulmonary embolism

• undergo further examination to exclude or confirm this diagnosis

• Thromboprophylaxis with anticoaulant or mechanical prophylaxis