What constitutes the diagnostic criteria for Systemic Inflammatory Response Syndrome (SIRS)?

What constitutes the diagnostic criteria for Systemic Inflammatory Response Syndrome (SIRS)?

• A. Presence of 2 or more of the following: Temp > 38 C or < 36 C; Pulse > 90; Respiratory rate > 20 or PaCO2 < 32; WBC > 11,000 or < 4,000 or > 10% bands
• B. Presence of 2 or more of the following: Temp > 39 C; Pulse > 100; Respiratory rate > 25; WBC > 12,000
• C. Presence of 3 or more of the following: Temp > 38 C or < 36 C; Pulse > 90; Respiratory rate > 20 or PaCO2 < 32; WBC > 11,000 or < 4,000 or > 10% bands
• D. WBC > 11,000 or < 4,000 or > 10% bands

Answer: (A)

SIRS is diagnosed when two or more systemic abnormalities are present across four criteria: body temperature, heart rate, respiration (or PaCO2), and white blood cell count. The best choice lists two or more of these specific findings with the standard thresholds: fever above 38 C or hypothermia below 36 C; pulse over 90 beats per minute; respiratory rate over 20 breaths per minute or PaCO2 less than 32 mm Hg; and WBC count above 11,000 or below 4,000, or more than 10% bands. This matches the classic SIRS definition exactly, making it the correct option. The other options fall short because they alter or limit the thresholds (for example, requiring higher fever, higher heart rate, or higher white cell counts), or require three criteria instead of two, or rely on a single abnormal value like WBC alone. SIRS hinges on the presence of any two of these four consistent criteria, not on stricter cutoffs or on a single parameter.

SIRS is diagnosed when two or more systemic abnormalities are present across four criteria: body temperature, heart rate, respiration (or PaCO2), and white blood cell count. The best choice lists two or more of these specific findings with the standard thresholds: fever above 38 C or hypothermia below 36 C; pulse over 90 beats per minute; respiratory rate over 20 breaths per minute or PaCO2 less than 32 mm Hg; and WBC count above 11,000 or below 4,000, or more than 10% bands. This matches the classic SIRS definition exactly, making it the correct option.

The other options fall short because they alter or limit the thresholds (for example, requiring higher fever, higher heart rate, or higher white cell counts), or require three criteria instead of two, or rely on a single abnormal value like WBC alone. SIRS hinges on the presence of any two of these four consistent criteria, not on stricter cutoffs or on a single parameter.