Gas Exhange

Introduction

Given the primary function of the respiratory system is the delivery of oxygen and the removal of carbon dioxide, assessment of these functions often play a central role in patient assessment. While these two functions are simplistic in concept, the physiologic processes involved are quite complex and often interrelated with other organ systems. While we associate hemoglobin with its roles for oxgyen delivery and carbon dioxide removal, proto-hemoglobin molecules have been in existance for more than 450million years. Early forms of life utilized iron containing molecules to facilitate electron transport in an anoxic environment. It was only with the advent of photosynthesis and the accumulation of oxygen in the atmosphere that hemoglobin took on its current role. While we will not spend more time of this aspect of oxygen delivery, complex life would not be possible if we had to rely of the amount of oxygen dissolved in plasma alone.

In this section we will focus on the tools we have available to assess gas exchange in the clinical setting. These include:

• Pulse Oximetry
• Resting Pulse Oximetry
• Exercise Pulse Oximetry
• 6 Minute Walk
• Overnight Pulse Oximetry
• Arterial Blood Gas Testing
• Venous Blood Gas Testing