Understanding Common Lab Values in Pulmonary Acute Care: A Primer for Occupational Therapists

For occupational therapists caring for patients with pulmonary conditions, a clear understanding of lab values is necessary in order to properly shape therapy strategies, ensure patient safety, and optimize therapy outcomes. In this article, we’ll take a look at the significance of common pulmonary lab values, how they can impact a patient’s ability to participate in therapy, and the practical implications for ensuring patient safety in pulmonary therapy.

Ensuring Patient Safety by Understanding Lab Values

Lab values are crucial indicators of a patient’s health status, providing essential information that guides clinical decision-making in pulmonary acute care settings. For occupational therapists, understanding these values is paramount to tailoring interventions that accommodate the patient’s current health status while mitigating risks associated with therapy activities. Key lab values that are particularly relevant to pulmonary care include hematocrit, hemoglobin levels, and markers for potential deep vein thrombosis (DVT) or pulmonary embolism (PE), such as D-dimer levels.

Hematocrit and Hemoglobin

These values indicate the concentration of red blood cells in the blood, directly impacting the body’s oxygen-carrying capacity. Lower levels may signify anemia, leading to increased fatigue and reduced tolerance for activities of daily living (ADLs) and functional mobility, which are critical considerations for therapy planning.

Hematocrit (Hct)

Normal range:

  • Women: 36–48%
  • Men: 40–50%

Notes on concerning values:
Lower than normal values may indicate anemia, which could contribute to fatigue and decreased oxygen transport capacity, impacting a patient’s tolerance for ADLs and functional mobility.

Significantly higher values might suggest dehydration or polycythemia, potentially increasing blood viscosity and the risk of thrombosis.

Hemoglobin (Hb)

Normal range:

  • Women: 12.1 to 15.1 gm/dL
  • Men: 13.8 to 17.2 gm/dL

Notes on concerning values:
Levels below the normal range can indicate anemia, leading to reduced oxygen-carrying capacity.

Elevated levels could be due to conditions that increase red blood cell production or concentration, such as smoking, living at high altitudes, or certain bone marrow disorders.


Elevated D-dimer levels can suggest the presence of an abnormal blood clot, pointing to conditions like DVT or PE. Understanding these risks is vital for adjusting therapy activities accordingly and helping to ensure patient safety during daily life.

Normal range:
Typically, a D-dimer level of less than 0.50 micrograms/mL or 500 ng/mL fibrinogen equivalent units (FEU) is considered normal.

Notes on concerning values:
It’s important to note that D-dimer can be elevated in many conditions other than DVT and PE, so it should be interpreted in the context of the patient’s clinical picture.

If a D-dimer test comes back elevated, it suggests an increased level of blood clot breakdown products in the bloodstream. While an elevated D-dimer can indicate several conditions, including DVT and PE, it’s not specific to these conditions alone. Further assessments are necessary to confirm or rule out DVT and PE.

Here’s what could be considered:

  • Ultrasound imaging: For suspected DVT, a venous ultrasound of the arms or legs is often the next step. This imaging technique can visualize blood flow in the veins and detect the presence of clots.
  • CT pulmonary angiogram (CTPA): For suspected PE, a CTPA scan is frequently performed. This imaging technique provides detailed images of the blood vessels in the lungs, allowing doctors to identify any blockages caused by blood clots.
  • Ventilation-perfusion (VQ) scan: Another option for diagnosing PE is a VQ scan. This test involves injecting a radioactive substance into the bloodstream and then taking images of the lungs to assess ventilation (airflow) and perfusion (blood flow). Areas of mismatch between airflow and blood flow could indicate a pulmonary embolism.
  • Clinical assessment: Symptoms such as leg pain, swelling, redness, and shortness of breath are crucial in guiding further assessment. A thorough physical examination combined with patient history can provide valuable information to support or refute the suspicion of DVT or PE.
  • Risk assessment tools: Various scoring systems, such as the Wells score for DVT or PE, help clinicians assess the probability of these conditions based on clinical features and other risk factors. These tools can aid in decision-making regarding the need for further testing.

It’s essential to interpret D-dimer results in the context of the patient’s clinical presentation, medical history, and risk factors. While an elevated D-dimer can raise suspicion for DVT or PE, additional tests are necessary to confirm the diagnosis and guide appropriate treatment.

International Normalized Ratio (INR)

If DVT or PE is confirmed, you’ll want to know whether the patient has an inferior vena cava (IVC) filter and consider INR levels prior to engaging in activity.

Normal range:

  • 0.8-1.2: therapeutic range for patients with venous thromboembolism (VTE), PE, and atrial fibrillation
  • 2.0 to 3.0: therapeutic range for stroke prophylaxis
  • 2.0-2.5: therapeutic range for patients at higher risk (prosthetic heart valves)
  • 2.5-3.5: therapeutic range for patients with lupus anticoagulant

pH and CO2 Levels

Pulmonary patients are also susceptible to acid base disorders. Respiratory alkalosis and acidosis are conditions characterized by changes in the pH of the blood due to alterations in the levels of carbon dioxide (CO2) in the body.

Respiratory Alkalosis

pH level: Respiratory alkalosis is indicated by a blood pH greater than 7.45.

CO2 levels: Carbon dioxide levels in the blood are decreased (hypocapnia), typically below 35 mmHg.

Symptoms: hyperventilation (rapid breathing), light-headedness, numbness or tingling in the extremities, confusion, and sometimes fainting.

Respiratory Acidosis

pH level: Respiratory acidosis is indicated by a blood pH lower than 7.35.

CO2 levels: Carbon dioxide levels in the blood are increased (hypercapnia), typically above 45 mmHg.

Symptoms: shortness of breath, confusion, fatigue, headache, and in severe cases, unconsciousness or respiratory failure.

To diagnose these conditions, blood gas analysis is often performed, which measures the levels of oxygen, carbon dioxide, and pH in the blood. Additionally, clinical symptoms and medical history are considered for proper diagnosis and treatment.

Managing supplemental oxygen for patients with chronic obstructive pulmonary disease (COPD) requires careful consideration to avoid potential complications such as oxygen-induced hypercapnia (excessive carbon dioxide levels) and oxygen-induced hypoventilation. Oxygen should be titrated to maintain arterial oxygen saturation (SaO2) within a target range of 88-92 percent. This range balances the need to prevent hypoxemia while minimizing the risk of oxygen-induced hypercapnia.

Integrating Lab Values into Therapy Planning

The integration of lab values into therapy planning is a nuanced process, requiring occupational therapists to balance therapeutic goals with the patient’s medical stability and safety. Here are practical strategies for incorporating lab value considerations into pulmonary therapy:

  • Individualized therapy planning: Tailor therapy activities based on the patient’s lab values, accommodating for potential limitations in physical endurance and oxygenation capacity. Modified Borg Scale can be used to monitor a patient’s response so that you can modify the intensity and duration of ADLs and functional mobility or select specific activities based on metabolic exercise tolerance (MET) levels that align with the patient’s current health status and priorities.
  • Monitoring for symptoms: Occupational therapists should look out for symptoms that may indicate changes in the patient’s condition, such as tachycardia, decreased Sp02, tachypnea, hyper or hypotension, increased fatigue, dyspnea on exertion, or signs of potential DVT or PE. Early recognition of these symptoms allows for timely adjustments to therapy interventions and prompt medical assessment when necessary.
  • Collaboration with the healthcare team: Close communication with the patient’s multidisciplinary team is essential for staying updated on lab values and sharing the patient response to occupational therapy with providers, nurses, physical therapists, and respiratory therapists. This collaborative approach ensures that occupational therapy interventions are aligned with the overall care plan, optimizing patient safety and outcomes.
  • Educating patients and caregivers: Part of ensuring patient safety involves educating patients and their caregivers about the significance of lab values and how they impact therapy participation. This includes discussions on recognizing signs of overexertion or adverse reactions with the use of target heart rate, Modified Borg Scale, MET levels, and underscoring the importance of adhering to therapy recommendations tailored to the patient’s specific health conditions.

Designing Effective and Safe Therapy Interventions

Understanding common lab values, standardized assessment tools, vital sign monitoring, and their impact on patient participation is a critical component of pulmonary occupational therapy in acute care settings.

Occupational therapists play a crucial role in integrating this knowledge into practice, ensuring that therapy interventions are not only effective but also safe for patients navigating the complexities of pulmonary conditions. By prioritizing patient safety through informed therapy planning and close collaboration with healthcare teams, occupational therapists contribute significantly to the holistic care and rehabilitation of individuals with pulmonary conditions.