Superiority of transcutaneous CO₂ over end-tidal CO₂ measurement for monitoring respiratory failure in nonintubated patients: A pilot study

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• 作者：Mathilde Lermuzeaux ; MD^a ; Henri Meric ; MSc^b ; Bertrand Sauneuf ; MD^a ; Salomé ; Girard ; MSc^a ; Hervé ; Normand ; MD ; PhD^c ; ^d ; ^e ; Fré ; dé ; ric Lofaso ; MD ; PhD^b ; ^f ; Nicolas Terzi ; MD ; PhD^c ; ^d ; ^g ; ^{terzi-n@chu-caen.fr" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Monitoring ; Transcutaneous CO2 ; End-tidal CO2 ; Acute respiratory failure ; Intensive care unit
• 刊名：Journal of Critical Care
• 出版年：2016
• 出版时间：February 2016
• 年：2016
• 卷：31
• 期：1
• 页码：150-156
• 全文大小：595 K

文摘

Arterial blood gas measurement is frequently performed in critically ill patients to diagnose and monitor acute respiratory failure. At a given metabolic rate, carbon dioxide partial pressure (Paco₂) is entirely determined by CO₂ elimination through ventilation. Transcutaneous partial pressure of carbon dioxide (PtcCO₂) monitoring permits a noninvasive and continuous estimation of arterial CO₂ tension (Paco₂). The accuracy of PtcCO₂, however, has not been well studied.

To assess the accuracy of different CO₂ monitoring methods, we compared PtcCO₂ and end-tidal CO₂ concentration (EtCO₂) to Paco₂ measurements in nonintubated intensive care unit (ICU) patients with acute respiratory failure.

Methods

During a 2-month period, we conducted a prospective observational cohort study in 25 consecutive nonintubated and spontaneously breathing patients admitted to our ICU. Arterial blood gases were measured at study inclusion, 30, 60, and 120 minutes later. At each sampling time, EtCO₂ was continuously monitored using a Philips Smart Capnoline Plus, and PtcCO₂ was measured using was measured using SenTec device. The aim of the study was to assess agreement between PtcCO₂ and Paco₂ and between EtCO₂ and Paco₂ in nonintubated ICU patients with acute respiratory failure. Bland-Altman techniques and Pearson correlation coefficients were used. The differences over time (at 30, 60, and 120 minutes) between Paco₂ and EtCO₂ and between PtcCO₂ and Paco₂ were evaluated using 1-way analysis of variance.

Results

Transcutaneous partial pressure of carbon dioxide and Paco₂ were well correlated (R = 0.97), whereas the correlation between EtCO₂ and Paco₂ was poor (R = 0.62) probably due to the presence of an alveolar dead space in a few patients, most notably in the group with chronic obstructive pulmonary disease. The difference over time remained stable for both Paco₂ vs EtCO₂ (analysis of variance; P = .88) and Paco₂ vs PtcCO₂ (P = .93).

Conclusion

We found large differences between EtCO₂ and Paco₂ in spontaneously breathing nonintubated ICU patients admitted for acute respiratory failure. Our study argues against the use of EtCO₂ monitoring in such patients but raises the possibility that PtcCO₂ measurement may provide reasonable estimates of Paco₂.