From the Guidelines
A carbon dioxide (CO2) level of 34 mmHg is considered below the normal range, as the normal range is defined as 34-46 mmHg, and values above this range indicate hypercapnia and potential type 2 respiratory failure, as stated in the BTS guideline for oxygen use in adults in healthcare and emergency settings 1.
Clinical Significance
The significance of a CO2 level of 34 mmHg is that it is at the lower boundary of the normal range, and any value below this could indicate hyperventilation or other respiratory issues. However, according to the BTS guideline, a value of 34 mmHg is still considered within the normal range, but just at the threshold 1.
Normal CO2 Range and Hypercapnia
The normal CO2 range in arterial blood is between 34-46 mmHg, and hypercapnia is defined as a PaCO2 above this range, indicating inadequate ventilation and potential type 2 respiratory failure, as seen in 22.7% of samples in a study of 3524 blood gas samples 1.
Clinical Implications
A CO2 level of 34 mmHg suggests that the patient's respiratory system is functioning at the lower limit of normal, and no specific treatment is needed for this value alone, but the clinical context should be considered when interpreting this result. The patient's symptoms, medical history, and other lab values should be taken into account to determine the overall clinical significance of this CO2 level.
From the Research
Significance of CO2 Level of 34
- A CO2 level of 34 is mentioned in the study 2 as the mean end-tidal carbon dioxide (ETCO2) level in patients with chronic obstructive pulmonary disease (COPD) in the emergency department.
- The study 2 found that the mean ETCO2 level was 34.23±10.86 mmHg, and the agreement between PCO2 and ETCO2 measurements was 8.4 mmHg with a precision of 11.1 mmHg.
- However, the study 2 also noted that there is only a moderate correlation between PCO2 and ETCO2 levels in COPD patients, and ETCO2 measurement should not be considered as a part of the decision-making process to predict PaCO2 level in COPD patients.
- The other studies 3, 4, 5, 6 do not specifically mention a CO2 level of 34, but they discuss the effects of elevated CO2 levels on various physiological processes, such as muscle regeneration 3, ventilatory management after cardiac arrest 4, and toxicity 5, 6.