Major Influence of Oxygen Supply on ¹³CO₂ : ¹²CO₂ Ratio Measurement by Nondispersive Isotope‐Selective Infrared Spectroscopy

Abstract

Oxygen supply to patients and, therefore, changes in gas composition in breath samples clearly influence 13CO2 measurement by NDIRS. This has to be taken into account in the clinical setting. Thus, oxygen supply during measurement of exhaled 13CO2 by NDIRS has to be avoided or maintained at a strictly constant level.

How to define initial poor graft function after liver transplantation? - a new functional definition by the LiMAx test

“…The age of recipients was 58 (49-61) years with 66% male gender. The direct preoperative labMELD score was 13 (7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18). The age of donors was 59 (42-67) years, with a DRI of 1.9 (1.6-2.2) ( Table 1).…”

“…Breath was collected by a face mask or if patients were mechanically ventilated by direct connection to the ventilator circuit. Ventilated patients received 100% oxygen to avoid interference with NDIRS [17]. No tests were performed during haemodialysis to avoid extrahepatic clearance.…”

Prediction of Postoperative Outcome After Hepatectomy With a New Bedside Test for Maximal Liver Function Capacity

“…Mechanically ventilated patients were respired with 100% oxygen during the test to reduce interference with nondispersive isotope-selective infrared spectroscopy. 25 After a minimum of 6 hours fasting, patients were placed in a resting horizontal position. Ten minutes prior to the injection with 13 C-methacetin, the baseline 13 CO 2 / 12 CO 2 ratio was recorded and the mean was used for the delta-over-baseline (DOB) calculation.…”

“…Total intravenous anesthesia was performed to avoid interference by volatile anesthetics. 25 The validity of the LiMAx test was evaluated with an assumed standard for liver function. Since volume and function correlate, the reduction from total volume to RLV after resection should have a proportional effect on the LiMAx values if no other hepatic injury occurred.…”

A rapid and accurate new bedside test to assess maximal liver function: a case report

“…13 C-methacetin (Euriso-top, Saint-Aubin, Cedex, France) is metabolized into acetaminophen and 13 CO 2 , which is pulmonarily exhaled. The exhaled air is collected using a face mask (Humedics GmbH, Berlin Germany), and the 13 CO 2 / 12 CO 2 ratio in the air is determined using a modified nondispersive isotope-selective infrared spectroscopy (FANci2-db16, Fischer Analysen Instumente, Leipzig, Germany, Humedics GmbH, Berlin, Germany) [11,13]. Based on the 13 CO 2 / 12 CO 2 ratio and the body weight, the cytochrome P450 1A2 activity is determined using the so-called LiMAx value with the unit μg/kg/h (μg methacetin/kg body weight/hour).…”