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Transcutaneous carbon dioxide measurements in fruits, vegetables and humans

A prospective observational study

Sochet, Anthony A.; Bessone, Stacey K.; Parilla, Nick W.; Nakagawa, Thomas A.

European Journal of Anaesthesiology: December 2019 - Volume 36 - Issue 12 - p 904–910
doi: 10.1097/EJA.0000000000001073
Original articles - Christmas issue

BACKGROUND Transcutaneous carbon dioxide measurement (TcCO2) is frequently used as a surrogate for arterial blood gas sampling in adults and children with critical illness. Data from noninvasive TcCO2 monitoring assists with clinical decisions regarding mechanical ventilation settings, estimation of metabolic consumption and determination of adequate end-organ tissue perfusion.

OBJECTIVES To report TcCO2 values obtained from various fruits, vegetables and elite critical care medicine specialists.

DESIGN Prospective, observational, nonblinded cohort study.

SETTINGS Single-centre, tertiary paediatric referral centre and organic farmers’ market.

PARTICIPANTS Vegetables and fruits included 10 samples of each of the following: red delicious apple (Malus domestica), manzano banana (Musa sapientum), key lime (Citrus aurantiifolia), miniature sweet bell pepper (Capsicum annuum), sweet potato (Ipomoea batatas) and avocado (Persea americana). Ten human controls were studied including a paediatric intensivist, a paediatric inpatient hospital physician, four paediatric resident physicians and four paediatric critical care nurses.


MAIN OUTCOME MEASURES TcCO2 values for each species and device response times.

RESULTS TcCO2 readings were measurable in all study species except the sweet potato. Mean ± SD values of TcCO2 for human controls [4.34 ± 0.37 kPa (32.6 ± 2.8 mmHg)] were greater than apples [3.09 ± 0.19 kPa (23.2 ± 1.4 mmHg), P < 0.01], bananas [2.73 ± 0.28 kPa (20.5 ± 2.1 mmHg), P < 0.01] and limes [2.76 ± 0.52 kPa (20.7 ± 3.9 mmHg), P < 0.01] but no different to those of avocados [4.29 ± 0.44 kPa (32.2 ± 3.3 mmHg), P = 0.77] and bell peppers [4.19 ± 1.13 kPa (31.4 ± 8.5 mmHg), P = 0.68]. Transcutaneous response times did not differ between research cohorts and human controls.

CONCLUSION We found nonroot, nontuberous vegetables to have TcCO2 values similar to that of healthy, human controls. Fruits yield TcCO2 readings, but substantially lower than human controls.

From the Division of Pediatric Critical Care Medicine, Johns Hopkins All Children's Hospital, St. Petersburg, Florida (AAS, NWP, TAN), Division of Anesthesiology and Critical Care Medicine, Johns Hopkins University, Baltimore, Maryland (AAS, TAN) and Department of Clinical Nutrition, Johns Hopkins All Children's Hospital, St. Petersburg, Florida, USA (SKB)

Correspondence to Anthony A. Sochet, MD, MS, Assistant Professor of Anesthesiology and Critical Care Medicine, Division of Pediatric Critical Care Medicine, Johns Hopkins University, Johns Hopkins All Children's Hospital, 501 6th Ave S., St#: 702A, St. Petersburg, FL 33701, USA Tel: +1 727 767 2912; e-mail:

Published online 28 August 2019

© 2019 European Society of Anaesthesiology