MEASUREMENT OF DEAD-SPACE IN A MODEL LUNG USING AN OSCILLATING INSPIRED ARGON SIGNAL

In a model lung, airways dead-space can be accurately measured using a forced inspired oscillating argon signal, which varies sinusoidally a bout a mean concentration of 6% v/v with an amplitude of +/-4% v/v. Wi th sinusoid forcing periods longer than 120 seconds, and at a breathin g rate of 13.4 breaths minute(-1), the mean airways dead-space can be measured with a standard error of less than 5%. Sinusoid forcing perio ds shorter than 120 s provided inaccurate estimates of dead-space and so should not. be used with this technique.