Hypoxia in a Patient With COVID-19

Case Study

A rapid response code was activated for a patient who developed acute dyspnea. On arrival of the condition team, the patient was found to be a 75-year-old male with a known history of chronic obstructive pulmonary disease (COPD), who was admitted to the hospital one day earlier for cough and fever secondary to coronavirus disease 2019 (COVID-19) pneumonia. The patient’s oxygenation had been stable on room air since admission. He had ambulated to the bathroom 30 min before the rapid response event and was having difficulty catching his breath since then.

Vital Signs

Temperature: 101.3 °F, axillary
Blood Pressure: 160/90 mmHg
Heart Rate: 120 beats per min (bpm)
Respiratory Rate: 35 breaths per min
Oxygen Saturation: 85% 4 L nasal cannula, 100% on a non-rebreather face mask

Focused Physical Examination

After donning proper personal protective equipment (PPE), a quick exam showed an elderly male in visible respiratory distress, using accessory muscles of respiration. The patient was unable to speak in complete sentences. The lung exam was significant for inspiratory crackles and expiratory wheezing in all lung fields. The cardiac exam was notable for tachycardia but was unremarkable otherwise.

Interventions

A cardiac monitor and pads were attached to the patient. A stat chest X-ray was ordered, and labs including complete blood count (CBC), electrolytes, and arterial blood gas were obtained. Chest X-ray showed multi-focal infiltrates that were worse than seen on the X-ray obtained admission ( Fig. 24.1 ). Labs were significant for a pH of 7.22, pO ₂ of 259, pCO ₂ of 95, and lactate of 3.4. The patient was given a dose of IV ceftriaxone, IV azithromycin, and IV dexamethasone per institutional protocol. The patient was transferred to the intensive care unit for a trial of non-invasive ventilation.

Final Diagnosis

Acute hypoxic respiratory failure secondary to COVID-19 infection.

COVID-19

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a part of the family of coronaviruses. The four coronaviruses, which are endemic, usually cause the common cold. However, SARS and Middle East respiratory syndrome have caused epidemics with high mortality rates. SARS-CoV-2 is closely related to SARS. The understanding of COVID-19, the disease caused by SARS-CoV-2, is evolving, and the information presented in this chapter is current as of February 2021. More up-to-date resources should be referred to for the latest information on the diagnosis and treatment of this illness.

The range of symptoms of COVID-19 varies from asymptomatic infection to severe respiratory failure requiring mechanical ventilation. Various risk factors have been identified which are associated with worse outcomes. These include older age, medical comorbidities such as cardiovascular disease, diabetes, hypertension, underlying lung disease, chronic kidney disease, obesity, history of smoking, and history of malignancies, particularly heme malignancies. Other factors such as viral mutations leading to the development of new variants have been associated with increased transmission and worse outcomes. However, this data is preliminary at this point and should be considered with caution.

As of the writing of this chapter, glucocorticoids such as dexamethasone are the only intervention that has been associated with a reduction in mortality associated with this illness. The antiviral agent remdesivir has been shown to reduce time to recovery in hospitalized adults. However, no reduction in mortality has been seen. Therapies such as interleukin-6 inhibitor tocilizumab, convalescent plasma, and antiviral antibodies are currently under investigation in clinical trials. The latest guidelines from the Centers for Disease Control and Prevention (CDC) should be sought for up-to-date SARS-CoV-2 directed therapy.

Hypoxia is the most common manifestation and acute complication of COVID-19. It is generally caused by ventilation-perfusion mismatch from consolidation. Other causes of V/Q mismatch, such as pulmonary embolism (PE; given the hypercoagulable state in active COVID infection) and intrapulmonary shunting, should also be considered in the differential for hypoxia. Based on current recommendations, a trial of non-invasive ventilation with a high-flow nasal cannula (HFNC) or bilevel positive airway pressure is preferred over direct intubation, depending on the patient’s respiratory status. Non-invasive ventilation is associated with the risk of aerosolization of viral particles, and institutional guidelines should be followed regarding PPE use in such cases.

Suggested Approach to a Patient With Acute Hypoxia from COVID-19

Based on the current guidelines (as of February 2021), the following approach can be used for the evaluation and management of hypoxia and respiratory distress in patients with COVID-19. The writers want to emphasize that SAR-CoV-2 and COVID-19 are evolving topics, and the recommendations are current as of the writing of this chapter. The latest guidelines from the CDC and other societies should be referred to for the latest updates in the management of COVID-19.

Focused History and Physical Examination

•

The acuity of signs and symptoms – acute worsening after initial recovery can be a sign of superimposed infection.
•

History of underlying lung disease such as asthma and COPD.
•

Physical exam should assess for airway, breathing, and circulation.
•

A pulmonary exam should be done to identify concomitant causes of worsening respiratory status such as wheezing (COPD or asthma exacerbation), fine crackles (heart failure exacerbation), and decreased breath sounds (pleural effusion).

Laboratory tests

•

CBC – to evaluate for worsening white count, coagulopathy.
•

Electrolyte panel – to evaluate for acidosis.
•

Arterial blood gas, including lactate – to evaluate the degree of hypoxia and acidosis.
•

Cultures including blood and sputum – if bacterial superinfection is suspected.
•

Respiratory viral panel (NAAT) – can be considered if concurrent infection with other viral agents is suspected.
•

d-dimer – can be obtained if suspicion of concomitant PE.
•

Procalcitonin – can help rue out bacterial superinfections; however, it is rarely reported fast enough to be helpful in a rapid response setting.

Imaging Studies

•

Chest X-ray – should be obtained in patients with worsening respiratory status to evaluate for superinfection, concomitant pulmonary edema, and pleural effusions.
•

CT angiogram – should be obtained if there is suspicion of PE, which is a known complication of COVID-19.

Therapeutic Interventions

The diagnosis and treatment options for COVID-19 are in constant flux. As the disease is relatively new, multiple aspects of this illness are still unknown. Very few COVID-19 directed therapies are established at this point, and numerous clinical trials are underway to determine what does and does not work. The latest CDC guidelines should be referred to for the up-to-date management essentials of COVID-19.

All patients should be assessed for airway, breathing, and circulation. Hypoxia should be treated to achieve blood oxygen saturation of 94% or above. Current guidelines recommend a trial of non-invasive ventilation to manage severe hypoxia, depending on clinical judgment and institutional policies. Empiric antibiotics for bacterial pneumonia can be considered if there is a high suspicion of bacterial superinfection or in immunocompromised patients. Again, clinical judgment should be used. Patients should be treated with low-dose dexamethasone (or equivalent) for new-onset hypoxia. Remdesivir has been approved by the Food and Drug Administration for COVID-19 and should be used per institutional policy. Other investigational therapies should be used per institutional guidelines. PE should be considered a contributor to hypoxia in the appropriate clinical setting.

Stepwise Approach to the Management of a Patient With COVID-19-Related Respiratory Failure

Step 1: Appropriate PPE should be established per institutional guidelines.
Step 2: The patient should be assessed for airway, breathing, and circulation. Supplemental O ₂should be initiated with goal oxygen saturation ≥94%.
Step 3: A chest X-ray should be obtained to evaluate for concomitant causes of respiratory distress.
Step 4: CBC, basic metabolic panel, and arterial blood gas should be obtained.
Step 5: Non-invasive ventilation should be considered before intubation in appropriate scenarios.
Step 6: Low dose dexamethasone should be initiated. Remdesivir and investigational therapies should be used per institutional guidelines.

Coding a Patient With COVID-19 Pneumonia With Acute Hypoxic Respiratory Failure

In patients with confirmed COVID-19 infection, clinicians should establish appropriate PPE before entering the room. If the patient is awake and able to follow commands, a trial of HFNC or continuous positive airway pressure (CPAP) can be started to improve saturations. If the patient cannot maintain saturation while on HFNC/CPAP or is not awake, bag-mask ventilation should be done immediately, followed by advanced airway placement. Intubation should be attempted by the most experienced provider available to avoid multiple attempts and reduce the risk of aerosolization.