Normal Waveform

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In a normal capnography reading, the EtCO₂ is between 35-45 millimeters of mercury (AHA, 2020; Neumar et al., 2020). As Figure 1 illustrates, the Alpha Angle (between the expiratory upstroke and alveolar plateau) is almost 90 degrees. This indicates a normal ventilation without obstruction. The alveolar plateau has a slight rise reaching our end-tidal carbon dioxide reading. The beta angle is also near 90 degrees, which indicates a normal ventilation. Notice that the baseline returns to zero all the way through this waveform reading. There are no corrective actions to be taken with this information.

Figure 1. Normal Ventilation Without Obstruction

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In a normal capnography reading, the end-tidal carbon dioxide is between 35 and 45 millimeters of mercury. As Figure 1 illustrates, the Alpha Angle (between the expiratory upstroke and alveolar plateau) is almost 90 degrees. This indicates a normal ventilation without obstruction. The alveolar plateau has a slight rise reaching our end-tidal carbon dioxide reading. The beta angle is also near 90 degrees. This indicates a normal ventilation. Notice that the baseline returns to zero all the way through this waveform reading. There are no corrective actions to be taken with this information.

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