NONINVASIVE MONITORING OF END-TIDAL CO2 VIA NASAL CANNULAS IN SPONTANEOUSLY BREATHING CHILDREN DURING THE PERIOPERATIVE PERIOD

Objective: To determine the correlation between end-tidal CO2 and Paco (2) values measured via nasal cannulas in spontaneously breathing chil dren during the perioperative period. Design: Prospective evaluation. Setting: Pediatric intensive/intermediate care unit in a tertiary care referral center. Patients: Thirty postoperative surgical and trauma p atients aged less than or equal to 18 yrs (average age 7.8 yrs [range 6 months to 16 yrs] and average weight 28.3 kg (range 8.5 to 69). Meas urements and Main Results: Spontaneously breathing, nonintubated patie nts with an arterial cannula in place were selected for study. End-tid al CO2 was sampled from nasal cannulas by a sidestream aspirator and w as estimated by infrared spectroscopy. The difference between Paco(2) and end-tidal CO2 was compared using linear regression analysis. A tot al of 55 blood gas measurements were obtained on the 30 patients. The Paco(2) to end-tidal CO2 gradient was less than or equal to 4 torr in 54 of the 55 samples. The mean Paco(2) was 39.5 +/- 3.3 torr (5.27 +/- 0.44 kPa) with a mean end-tidal CO2 value of 39.7 +/- 3.8 torr (5.29 +/- 0.51 kPa). Linear regression analysis of arterial vs. end-tidal CO 2 yielded a slope of 0.992 and p = .0001. Conclusions: End-tidal CO2 m easurement by infrared spectroscopy provided an accurate estimation of Paco(2) in this patient population. Its use may limit the need for in vasive monitoring and/or repeated arterial blood gas analysis.