What should be monitored in COVID-19 (Coronavirus Disease 2019) positive patients?

Monitoring COVID-19 Positive Patients

COVID-19 positive patients require systematic monitoring of vital signs, laboratory parameters (particularly coagulation markers and organ function), and oxygen saturation, with the intensity of monitoring escalating based on disease severity and hospitalization status. 1

Essential Vital Signs Monitoring

All hospitalized COVID-19 patients must be continuously monitored for heart rate, pulse oxygen saturation (SpO2), respiratory rate, and blood pressure. 1

• Target SpO2 should be maintained >90-96%, though evidence suggests targeting the upper end of this range (closer to 96%) may be prudent given concerns about "silent hypoxemia" where patients present with severe hypoxemia disproportionate to symptoms 2, 3
• Respiratory rate ≥26 breaths per minute is a critical threshold associated with need for continuous positive airway pressure (CPAP) 4
• Temperature monitoring is essential, with fever ≥38°C indicating higher risk for clinical deterioration 4

Pulse Oximetry Considerations

Home pulse oximetry monitoring should be implemented for outpatients at high risk of progression, with alerts triggered when SpO2 falls below 94%. 5, 6

• Be aware that pocket oximeters and smartphone-based systems have questionable accuracy, particularly when saturation falls below 90% 6
• Measurements fluctuate rapidly when arterial oxygen falls on the steep portion of the dissociation curve 6
• Accuracy is compromised with diminished pulsatile blood flow, severe hypoxemia, and dyshemoglobinemias 6

Laboratory Monitoring for Coagulopathy

All COVID-19 patients presenting to hospital should have baseline coagulation studies obtained: D-dimer, PT/PTT, platelet count, and fibrinogen. 1

Risk Stratification Thresholds for Hospital Admission

The following laboratory values indicate need for hospital admission and close monitoring 1:

• D-dimer markedly raised 3-4 fold above upper limit of normal
• Prothrombin time prolonged
• Platelet count <100 × 10⁹/L
• Fibrinogen <2.0 g/L

Monitoring Frequency in Hospitalized Patients

Monitor coagulation parameters at least twice daily in all hospitalized COVID-19 patients. 1

• D-dimer >6 times upper limit of normal is a consistent predictor of thrombotic events and poor prognosis 1
• PT and platelet counts should be monitored at least twice daily 1
• Worsening of these parameters predicts need for more aggressive critical care and consideration of experimental therapies 1

Important caveat: Do not use D-dimer levels or other biomarker thresholds solely to guide anticoagulation regimens outside clinical trial settings 1

Organ Function Monitoring

Hospitalized patients require regular monitoring of comprehensive organ function panels. 1

Hepatic Monitoring

• Monitor liver enzymes (ALT, AST), bilirubin at baseline 1
• For patients on potentially hepatotoxic COVID-19 treatments (lopinavir-ritonavir, chloroquine, hydroxychloroquine, tocilizumab), monitor liver function tests twice weekly 1
• Tocilizumab should not be initiated if ALT or AST >10 times upper limit of normal 7
• Discontinue hepatotoxic treatments if moderate-to-severe liver injury develops 1

Renal and Metabolic Monitoring

Monitor the following parameters regularly 1:

• Creatinine and urea nitrogen
• Urine output
• Myocardial enzymes (troponin)
• Electrolytes and acid-base status via arterial blood gas analysis

Hematologic Monitoring

Monitor complete blood count with differential regularly. 1

• Lymphopenia (absolute lymphocyte count <0.87 × 10⁹/L) is characteristic of COVID-19 1
• Neutrophil percentage typically increases (>72%) 1
• Eosinopenia is common 1

Inflammatory Markers

C-reactive protein (CRP) and procalcitonin (PCT) should be monitored to assess disease severity and identify bacterial superinfection. 1

• Rising PCT suggests bacterial superinfection requiring antibiotic therapy 1
• CRP elevation correlates with disease severity 1

Chest Imaging

Serial chest imaging (CT or chest X-ray) should be performed to monitor disease progression and response to treatment. 1

• Baseline imaging at presentation 1
• Follow-up imaging based on clinical trajectory and respiratory status changes 1

Special Monitoring Considerations

For Patients on Specific COVID-19 Therapies

Tocilizumab requires specific monitoring protocols: 7

• Do not initiate if ANC <1,000/mm³ or platelets <50,000/mm³
• Monitor neutrophils and platelets during treatment
• Measure liver tests promptly if symptoms of liver injury develop (fatigue, anorexia, right upper quadrant discomfort, dark urine, jaundice)

For Patients with Pre-existing Liver Disease

• Screen for HBsAg if systemic corticosteroids or immunosuppressants will be used for ≥7 days 1
• Initiate HBV antiviral prophylaxis to prevent reactivation 1

Outpatient Monitoring

High-risk outpatients should have structured remote monitoring systems with: 5

• Daily SpO2 measurements with automatic alerts for SpO2 <94%
• Heart rate monitoring
• Breathlessness scoring
• Clinical review of trends showing declining SpO2, increasing heart rate variability, or worsening breathlessness

Predictive monitoring: SpO2 and heart rate data from the preceding two days can predict SpO2 alerts with 88% specificity, allowing early identification of patients at risk for deterioration 5