Colorimetric CO2 Research Articles

Colorimetric CO2 Detector to Improve Effective Mask Ventilations in Very Preterm Infants: A Pilot Randomized Controlled Study

Introduction: End-tidal CO2 (ETCO2) detector is currently recommended for confirmation of endotracheal tube placement during neonatal resuscitation. Whether it is feasible to use ETCO2 detectors during mask ventilation to reduce risk of bradycardia and desaturations, which are associated with increased risk of death in preterm babies, is unknown. Methods: This is a pilot randomized controlled trial (NCT04287907) involving newborns 24 + 0/7 to 32 + 0/7 weeks gestation who required mask ventilation at birth. Infants were randomized into groups with or without colorimetric ETCO2 detectors. Combined duration of any bradycardia (<100 bpm) and time below prespecified target oxygen saturation (SpO2) as measured by pulse oximetry were compared. Results: Fifty participants were randomized, 47 with outcomes analysed (2 incomplete data, 1 postnatal diagnosis of trachea-oesophageal fistula). Mean gestational age and birthweight were 28.5 ± 1.9 versus 29.4 ± 1.6 weeks (p = 0.1) and 1,252.7 ± 409.7 g versus 1,334.6 ± 369.1 g (p = 0.5) in the intervention and control arm, respectively. Mean combined duration of bradycardia and desaturation was 276.7 ± 197.7 s (intervention) and 322.7 ± 277.7 s (control) (p = 0.6). Proportion of participants with any bradycardia or desaturation at 5 min were 38.1% (intervention) and 56.5% (control) (p = 0.2). No chest compressions, epinephrine administration, or death occurred in the delivery room. Conclusion: This pilot study demonstrates the feasibility of a trial to evaluate colorimetric ETCO2 detectors during mask ventilation of very preterm infants to reduce bradycardia and low SpO2. Further assessment with a larger population will be required to determine if ETCO2 detector usage at resuscitation reduces risk of adverse outcomes, including death and disability, in very preterm infants.

Colorimetric CO2 Indicators.

Carbon dioxide, CO2, is an essential part of life, in that through green plant photosynthesis it is used to generate food and fuel and is generated in both aerobic and anaerobic respiration. Industrially, it is used in fire extinguishers, supercritical fluid extractions, and food packaging. Environmentally, it is in the atmosphere, hydrosphere, and biosphere and is responsible for global warming and the acidification of the oceans. The monitoring of CO2 in the gas phase is usually carried out using FTIR spectroscopy, whereas the measurement of dissolved CO2 usually involves an electrochemical device. Excitingly, the most recent forms of CO2 indicators appear to offer significant advantages over current methods, such as simplicity, low cost, and portability. This Account highlights the work of the Mills group on transforming CO2 colorimetric indicator technology from the usual water-based (i.e., "wet") indicator form to dry CO2-sensitive inks, pigments, plastics, and adhesives. Initially, the basic theory associated with colorimetric CO2 indicators is described, and the simple relationship between indicator absorbance and the partial pressure of CO2, PCO2, established. The early work on CO2-sensitive inks is then described, where such inks comprise a hydrophilic pH-sensitive dye anion, coupled with a lipophilic quaternary ammonium cation, dissolved in a nonaqueous solution of a polymer which, when cast, forms a dry ink film that gives a reversible color response when exposed to CO2 both in the gas phase and dissolved in solution. The ability to tune the sensitivity of a CO2 ink film to the desired application through the judicious choice of the pH indicator dye and base concentration is described. The dependence of the sensitivity of a CO2 ink film on temperature is used to create a temperature indicator, and the ability to tune the ink, to respond to high levels of CO2, is used to create a fizziness indicator for carbonated drinks. Very sensitive CO2 inks are used to make a vacuum and a general air-pressure indicator. The more recent development in CO2 indicator technology is described in which CO2 inks are used to coat silica particles to make a range of different CO2-sensitive pigments, which, when incorporated into a plastic, through extrusion, produce a range of novel CO2-sensitive plastic films that have many notable advantages over their ink film counterparts. Examples are then given of such plastic films being used for dissolved CO2 measurements in salt water, for food packaging, and as an early wound-infection indicator. Finally, the recent incorporation of a CO2-sensitive pigment into a pressure sensitive adhesive to make an after opening freshness tape is described briefly. Although most commercial CO2 indicators are assessed by eye and so are limited to qualitative analysis, this work shows that colorimetric CO2 indicators can be used for quantitative analysis through absorbance measurements. Nowadays, such measurements can be readily made using just a digital camera and color analysis software via digital camera colorimetry, DCC, which is likely to have a significant impact on the widespread use of the CO2 indicators described herein, their commercial viability, and their potential areas of application.

Spiropyran-based chromic hydrogels for CO2 absorption and detection.

By enabling rapid, cost-effective, user-friendly and in situ detection of carbon dioxide, colorimetric CO2 sensors are of relevance for a variety of fields. However, it still remains a challenge the development of optical chemosensors for CO2 that combine high sensitivity, selectivity and reusability with facile integration into solid materials. Herein we pursued this goal by preparing hydrogels functionalized with spiropyrans, a well-known class of molecular switches that undergo different color changes upon application of light and acid stimuli. By varying the nature of the substituents of the spiropyran core, different acidochromic responses are obtained in aqueous media that allow discriminating CO2 from other acid gases (e.g., HCl). Interestingly, this behavior can be transferred to functional solid materials by synthesizing polymerizable spiropyran derivatives, which are used to prepare hydrogels. These materials preserve the acidochromic properties of the incorporated spiropyrans, thus leading to selective, reversible and quantifiable color changes upon exposure to different CO2 amounts. In addition, CO2 desorption and, therefore, recovery of the initial state of the chemosensor is favored by irradiation with visible light. This makes spiropyran-based chromic hydrogels promising systems for the colorimetric monitorization of carbon dioxide in a diversity of applications.

Front Cover: A Tunable Colorimetric Carbon Dioxide Sensor Based on Ion‐Exchanger‐ and Chromoionophore‐Doped Hydrogel (Anal. Sens. 6/2023)

The cover feature image shows a two-dimensional (2D) colorimetric carbon dioxide (CO2) sensor composed of a gas-permeable polypropylene film (25 μm thick) and a signal transduction hydrogel layer (30 μm thick). The hydrogel layer contained a pH sensitive chromoionophore to indicate the CO2 induced pH change, and a cationic amine to further capture CO2 through the carbamate formation reaction. With this 2D colorimetric CO2 optode, the CO2 release from yeast-catalyzed flour fermentation was successfully monitored. More information can be found in the Research Article by Jingying Zhai, Xiaojiang Xie, and co-workers.

Robot-accelerated development of a colorimetric CO2 sensing array with wide ranges and high sensitivity via multi-target Bayesian optimizations

The one-variable-at-a-time method for sensor R&D has received extensive research effort, yet it has reached the local maxima for specific sensing characteristics. To achieve the quasi-global maxima for suitable sensors, we developed the Design–Build–Test–Machine learning (DBTM) method for efficiently developing sensors on demand. In addition, the automation of the preparation and characterization processes frees researchers from labor-intensive work, generates adequate high-quality data, and enables researchers to discover valuable information in high-dimensional space. As a proof-of-concept, we built a high-throughput algorithm-driven autonomous system (HAAS) that supports the DBTM approach for developing a CO2 sensor. With the DBTM approach, we can simultaneously optimize multiple sensor units, each for a specific concentration interval. Therefore, such an array can achieve an extensive range and sound sensitivity. Our work demonstrates the superiority of the DBTM method for multi-target and multi-variable sensor development. In contrast to single target optimization in other research areas, multiple characteristics should be improved for sensors. Our multi-target optimization algorithm optimizes four sensor characteristics. Our sensor array could rapidly detect CO2 concentrations from 400 ppm to 30 % with a root mean square error (RMSE) of 0.27 %. The DBTM method is anticipated to be a new paradigm and accelerator of practical application for sensors after the initial proof of the sensing mechanism.

Determination of Co2+ ions in blood samples: A multi-way sensing based on NH2-rich carbon quantum dots

Multiple forms of detecting Co2+ are reported in this work to quantify these ions in real blood plasma samples. Carbon Quantum Dots (CQDs) were used as a fluorescent nanoprobe. The CQDs were obtained from a bottom-up approach using a hydrothermal method and choline chloride and branched poly(ethyleneimine) as precursor molecules. Several spectroscopic and structural characterizations were performed. The efficient fluorescence quenching of CQDs related to the Co2+ ion was used for the detection of the analyte, generating a sensing strategy with a limit of detection (LOD) of 0.98 μmol L−1. Furthermore, the interaction between the Co2+ ion with the CQDs resulted in the color change of the solution from colorless to pale yellow. Thus, a colorimetric Co2+ sensor was also developed, since there was an absorption band at 315 nm attributed to the formation of the complex CQD + Co2+. The colorimetric method showed an excellent sensitivity to Co2+, with a LOD of 3.01 μmol L−1. In addition, Principal Component Analysis (PCA) together with Linear Discriminant Analysis (LDA) were used successfully to distinguish different concentrations of Co2+ and different interfering ions present in the solution. Finally, a real sample of blood plasma was properly treated and doped with different concentrations of Co2+, which was successfully quantified via fluorescent method. Therefore, the CQDs obtained in this work are a powerful and versatile Co2+ detection tool.

A Colorimetric CO2 Hydration Assay for Facile, Accurate, and Precise Determination of Carbonic Anhydrase Activity

A simple, reliable, and universal method is demanded for routine determination of carbonic anhydrase (CA) activity, overcoming the limitations of previous assays that are inaccurate, complicated, expensive, or limited to a specific enzyme family. The most widely used Wilbur–Anderson assay was modified to improve the speed, accuracy, and precision by employing a temperature controllable UV/Vis spectrophotometer and the pH indicator phenol red. The experimental setting, measurement, and data analysis were facile and straightforward. The assay was validated using a commercially available bovine CA, showing that the obtained activity was directly proportional to the amount of enzyme. The measured activity (2540 WAU mg−1) agreed well with the previously reported data. The comparison results with esterase assay showed that the CO2 hydration assay should not be substituted by the esterase assay in the measurement of CA activity. The simple and reliable colorimetric method can be widely adopted for the routine determination of CO2 hydration activity, substituting for the traditional Wilbur–Anderson assay.

Highly sensitive and selective colorimetric sensing of CO2 for biomedical applications

The concentration of carbon dioxide (CO2) in unhealthy people differs greatly from healthy people. High-precision CO2 detection with a quick response time is essential for many biomedical applications. A major focus of this research is on the detection of CO2, one of the most important health biomarkers. We investigated a low-cost, flexible, and reliable strategy by using dyes for colorimetric CO2 sensing in this study. The impacts of temperature, pH, reaction time, reusability, concentration, and dye selectivity were studied thoroughly. This study described real-time CO2 analysis. Using this multi-dye method, we got an average detection limit of 1.98 ppm for CO2, in the range of 50–120 ppm. A portable colorimetric instrument with a smartphone-assisted unit was constructed to determine the relative red/green/blue values for real-time and practical applications within 15 s of interaction and the readings are very similar to those of an optical fiber probe. Environmental and biological chemistry applications are likely to benefit greatly from this unique approach.

Enhanced ZIF-8-enabled colorimetric CO2 sensing through dye-precursor synthesis

The accumulation of carbon dioxide (CO2) within enclosed spaces, along with volatile organic compounds, under certain humidity, temperature, and ventilation conditions is associated with detrimental human health symptoms such as fatigue. Color-based chemical sensing is a promising approach to detect CO2 levels relevant to indoor air quality through producing fast, quantifiable output visible to the naked eye. In a prior work, a colorimetric gas sensor was fabricated through synthesizing the metal-organic framework, ZIF-8, as the adsorbent, followed by post-synthetic mixing with a dye, phenol red (PSP), and primary amine, ethylenediamine (ED). While this sensor (termed PSP-ED/ZIF-8) maintained its structural integrity in atmospheric conditions and exhibited an increasing fuchsia-to-yellow color change with increasing CO2 levels in dry environment, the colorimetric response greatly suffered in the presence of humid CO2. In this work, a significantly improved colorimetric CO2 sensor (referred to as ED/PSP:ZIF-8) is accomplished through directly incorporating phenol red in the ZIF-8 metal and linker precursor solutions and then blending with ethylenediamine. MATLAB-generated color distributions and in-situ ultraviolet-visible (UV-Vis) spectroscopic studies quantitatively demonstrate an enhanced colorimetric gas response of ED/PSP:ZIF-8 compared to that of PSP-ED/ZIF-8 across an important range of CO2 for indoor air quality monitoring (500 – 3500 ppm) and across a range of humidity. The new sensor also exhibits high selectivity to CO2 compared to select volatile organic compounds, such as acetone and ethanol, which contribute to human health symptoms experienced indoors. The enhanced performance is attributed to the proposed incorporation of phenol red within ZIF-8, while maintaining the chemical stability of the MOF.

Application of colorimetric sensor in monitoring dissolved CO2 in natural waters

Dissolved CO2 originating from underground structures at high concentrations may pose a threat to public and environmental health. Therefore, a convenient monitoring technique that allows fast detection of dissolved CO2 needs to be developed. In this study, a low-cost colorimetric CO2 sensor was applied for monitoring dissolved CO2. The sensor is composed of an acrylic reactor, cresol red pH indicator solution, and a gas-permeable membrane, and the performance of the sensor was tested for the detection of dissolved CO2 at the range of 2–800 mg CO2 L−1. Color change of the detection solution within the sensor was mainly dependent on CO2 dissolved in the water sample. This was analyzed using an RGB program that extracts the red, green, and blue intensity of a target color on a scale of 0–255. ΔGB, an index of CO2 concentration corresponding to the change in intensity of green (G) and blue (B) extracted by the RGB program, exhibited a linear relationship with dissolved CO2 concentrations (r2 > 0.95, p < 0.005). In the field, the sensor was able to measure dissolved CO2 between 10 and 411 mg CO2 L−1 within 1 min. Overall, our CO2 sensor has high potential to be used in detection of dissolved CO2 in groundwater and surface waters.

Pilot Testing of the "Turbidimeter", a Simple, Universal Reader Intended to Complement and Enhance Bacterial Growth Detection in Manual Blood Culture Systems in Low-Resource Settings.

Bloodstream infections and antimicrobial resistance are an increasing problem in low-income countries. There is a clear need for adapted diagnostic tools. To address this need, we developed a simple, universal reader prototype that detects bacterial growth in blood culture bottles. Our “turbidimeter” evaluates bacterial growth, based on the turbidity of the broth and the color change of the colorimetric CO2 indicator in commercially available blood culture bottles. A total of 60 measurements were performed using 10 relevant microbial species, spiked in horse blood, to compare the turbidimeter’s performance with that of an automatic reference system. The turbidimeter was able to detect growth in all but one of the spiked blood culture bottles. In the majority (7/10) of the species tested, time-to-detection of the turbidimeter was shown to be non-inferior to the reference automated time-to-detection. This was, however, only the case when both the turbidity and color change in the colorimetric CO2-indicator were used to evaluate growth. We could not demonstrate the non-inferiority of the turbidity measurement alone. Overall, the turbidimeter performed well, but we also identified some improvements that will be implemented in the next version of the prototype.

Plug and Play Colorimetric Carbon Dioxide Sensor

Carbon dioxide measurement is an important endeavor in many industries such as food packaging, grain storage and health industry. This work presents a reversible, plug and play and low-cost colorimetric CO2 sensor calibrated in a proper concentration ranging from 1% to 3% of CO2. The sensor showed potential for improvement to increase resolution, for measuring lower CO2 concentrations and for more accurate readings.

Functionalized Metal-Organic Framework Toward Colorimetric CO2 Sensing in Indoor Air Environment

Carbon dioxide (CO2) has been shown to contribute to human health consequences indoors, such as shortness of breath, nasal and optic irritation, dizziness, and nausea. Given these precarious conditions for human health, various efforts have emerged toward development of CO2 monitors for indoor deployment. The chief problem in gas sensing is the design of a sensor that is highly-sensitive and selective to targeted species, energy-efficient, inexpensive to fabricate, stable, and convenient for users. One of the most popular CO2 sensors in commercial operations is the nondispersive infrared (NDIR) CO2 sensor. While boasting high accuracy and longevity, the CO2 NDIR sensor has traditionally been challenged by power consumption, cost, and bulky dimensions. In contrast to the NDIR sensing technology, colorimetric sensing retains several advantages, including easy preparation, user convenience, and obvious responses detectable by the human eye.In this work, we situate metal–organic frameworks (MOFs) as highly-porous, crystalline sorbents for sensitive colorimetric CO2 detection. In particular, a zeolitic imidazolate framework (ZIF) is chosen as the sorptive material due to its chemical stability and tunable CO2 affinity. The colorimetric gas sensor is developed by incorporating a CO2-affinative basic function and a pH indicator into the ZIF. The developed colorimetric CO2 sensor exhibits an obvious response to a wide range of CO2 levels of interest to indoor air detection (with a lower limit of detection below 1,000 ppm CO2). Powder X-ray diffraction confirms its chemical stability over one month in ambient conditions. Ultraviolet-visible spectroscopy reveals quantitative differences in colorimetric responses across a span of CO2 concentrations (700 – 7,500 ppm CO2). The color response is attributed to a two-step reaction mechanism whereby the pH indicator deprotonates the reaction intermediate between the adsorbed CO2 reacting with the basic function, shifting the pH and inducing a color change. Given its simple fabrication, rapid and obvious response, and stability in ambient environment, the ZIF-based colorimetric sensor provides a promising route for an improved indoor air quality monitoring. Acknowledgements We would like to thank the National Science Foundation for support in the form of a Graduate Research Fellowship (GRF) and Grant # 1903188, as well as the Bakar Fellows Program.

Non-invasive carbon dioxide monitoring in neonates: methods, benefits, and pitfalls.

Wide fluctuations in partial pressure of carbon dioxide (PaCO2) can potentially be associated with neurological and lung injury in neonates. Blood gas measurement is the gold standard for assessing gas exchange but is intermittent, invasive, and contributes to iatrogenic blood loss. Non-invasive carbon dioxide (CO2) monitoring has become ubiquitous in anesthesia and critical care and is being increasingly used in neonates. Two common methods of non-invasive CO2 monitoring are end-tidal and transcutaneous. A colorimetric CO2 detector (a modified end-tidal CO2 detector) is recommended by the International Liaison Committee on Resuscitation (ILCOR) and the American Academy of Pediatrics to confirm endotracheal tube placement. Continuous CO2 monitoring is helpful in trending PaCO2 in critically ill neonates on respiratory support and can potentially lead to early detection and minimization of fluctuations in PaCO2. This review includes a description of the various types of CO2 monitoring and their applications, benefits, and limitations in neonates.

Amine-functionalized metal-organic framework ZIF-8 toward colorimetric CO2 sensing in indoor air environment

Carbon dioxide (CO2) has been shown to contribute to human health consequences indoors, such as shortness of breath, nasal and optic irritation, dizziness, and nausea. In this work, we explore the potential of metal–organic frameworks (MOFs) as highly-porous, crystalline sorbents for sensitive colorimetric CO2 detection. In particular, the zeolitic imidazolate framework (ZIF-8) is chosen as the sorptive material due to its chemical stability and tunable CO2 affinity. The colorimetric gas sensor is developed in methanol with three components: (i) MOF ZIF-8 as a high surface area adsorbent; (ii) ethylenediamine (ED) as the CO2-affinitive basic function; and (iii) phenolsulfonpthalein (PSP) as the pH indicator. Colorimetric assays and ratiometric analysis confirm a colorimetric response to variable CO2 concentrations of relevance to indoor air quality. The color response is attributed to a zwitterion mechanism whereby ED reacts with CO2 to form a zwitterionic intermediate. This intermediate is then deprotonated by the pH indicator, shifting the pH and inducing a color change. Given its simple fabrication, rapid and obvious response, and stability in ambient environment, the ZIF-8-based colorimetric sensor provides a promising route for an improved indoor air quality monitoring.

Highly efficient colorimetric CO2 sensors for monitoring CO2 leakage from carbon capture and storage sites

Carbon capture and storage (CCS) technology used for reducing anthropogenic CO2 emissions involves the capture of CO2 from industrial sources and its injection into geological sinks, such as oil reservoirs and abandoned gas fields. To ensure environmental and public safety in implementing CCS technology, efficient CO2-monitoring technology must be developed to detect potential CO2 leakage from CCS sites. Conventional CO2 sensors used for monitoring CCS sites are typically high in cost and require professional staff for maintenance. In this study, we developed a portable and low-cost colorimetric CO2 sensor with high soil CO2 detection efficiency for CCS sites. The sensor consists of a detection solution that contains the pH indicator cresol red encapsulated with a gas-permeable membrane. When CO2 enters the sensor through the membrane, the color of the pH indicator changes and this was quantified using an RGB (red, green, blue) application (app), an app that measures the RGB values of a given color. The change in G and B values of the detection solution showed a significant linear relationship with soil CO2 concentration determined via non-dispersive infra-red (NDIR) CO2 sensor (r2 = 0.98, p = 0.001), and thus these values were used for quantification of CO2 concentration. Tests using CO2-injection chamber showed that the optical CO2 sensors can detect soil CO2 concentration of 0.1 to 30% within a few minutes. Field studies conducted at a natural CO2 vent and an artificial CO2 leakage site showed that the optical CO2 sensors can be applied in analyzing surficial CO2 leakage patterns. The advantage of this optical CO2 sensor when applied to field monitoring is that it is inexpensive and has few installation restrictions. Therefore, this optical CO2 sensor has a strong potential for use in monitoring CO2 leakages from CCS sites.

Evaluation of an ‘After Opening Freshness (AOF)’ label for packaged ham

Abstract A new type of commercial time-temperature indicator, TTI, namely the ‘After Opening Freshness Label’, i.e. AOF label, is evaluated. The label comprises a plastic film colorimetric CO2 indicator layer encapsulated in a polymer sheath, the permeability of which controls the rate of diffusion of the CO2 in to and out of the indicator film. The CO2 sensitive indicator film inside the label is relatively fast in responding (recovering its original colour in 26 min at 25 °C) when the ambient atmosphere is changed from that of the MAPed package (containing 25% CO2) to air, but when encapsulated in the polymer sheath used in the AOF label, which uses polyethylene terephthalate, PET, as a gas diffusion barrier, under the same conditions its recovery time is ca. 30 h (at 25 °C). Key to its commercial function – as a consume within indicator – at 5 °C, the label’s recovery time is ca. 96 h (i.e. 4 days). While UV/Vis spectrophotometry is used to characterise the optically transparent CO2 indicator, photography, coupled with digital image colour analysis is used to characterise the AOF label. A study of the kinetics of colour recovery of the AOF label as a function of temperature revealed an activation energy, Ea, of colour recovery of ca. 43 kJ mol−1, which is similar to a number of different food spoilage processes. The potential of the AOF label as a ‘consume within’ indicator to help minimise the large amount of unnecessary household food waste associated with many developed countries is discussed briefly.

Carbon dioxide colorimetric indicators for food packaging application: Applicability of anthocyanin and poly-lysine mixtures

Abstract Microbial spoilage of food is accompanied by a pronounced production of carbon dioxide (CO2). Sensors that visually highlight the presence of CO2 inside the food packages can be thereby used as labels for indicating the freshness of the marketed products. Moreover, the monitoring of the optimal CO2 level is also required under modified-atmosphere packaging (MAP) conditions, being this gas prone to permeate food and package materials. In this study we investigated the CO2 sensing performance of a food grade mixture constituted of an aminoacid (L-Lysine) a polypeptide (e-poly- l -lysine, EPL) and natural occurring dyes (anthocyanins). Test carried in distilled water showed that the mixture at 0.01% w/v concentration level was very reactive, turning from azure to purple colour in less than five minutes, even when exposed to 2.5% gaseous CO2. A reverse direction transition was also observed for the 0.1% w/v solution when the CO2 levels fall down below 20%. The system was then dissolved in a biopolymeric matrix giving a coating totally constituted of food grade ingredients and usable as colorimetric CO2 indicator for cold preserved food.

Inkjet-printed CO2 colorimetric indicators

Colorimetric CO2 indicators were prepared by printing pH dyes (M-cresol purple or phenol red, tetrabutylammonium hydroxide, ethylcellulose, 1:2 ethanol:1-butanol solvent), using a commercially available thermal inkjet printer, on either cellulose paper or plastic transparency film. Indicators inks printed on the papers had higher sensitivity to CO2, greater color change, and more producible than those printed on plastic film. Varying the print intensities of the two pH dyes resulted in multiplexed indicators with tunable sensitivity and expanded detection concentration range towards CO2. The ink-jet printing method is simple and highly flexible for the development of indicator to detect CO2 – a gas indicative of product quality in many food products. Further optimization can potentially lead to application of the indicators in intelligent food packaging systems.

Prehospital Endotracheal Intubation in Warm Climates: Caution is Required

BackgroundOut-of-hospital endotracheal intubation is a frequent procedure for trauma care. Nevertheless, in warm climates, sunlight and heat can interfere with the flow of the usual procedure. They can affect the equipment and hinder the operator. There are few data on this issue. The presentation of this case highlights three common complications that may occur when intubating under a hot and bright sun. Case ReportA 23-year-old man had a car accident in Djibouti, at 11:00 a.m., in broad sunlight. The heat was scorching. Due to a severe head trauma, with a Glasgow Coma Scale score of 8, it was decided to perform an endotracheal intubation. The operator faced three problems: the difficulty of seeing inside the mouth in the bright sunlight, the softening of the tube under the influence of the heat, and the inefficiency of colorimetric CO2 detectors in the warm atmosphere in confirming the proper endotracheal tube placement. Why Should an Emergency Physician Be Aware of This?Solutions are simple, but must be known and planned ahead, prior to beginning the procedure: Putting a jacket over his head while doing the laryngoscopy would solve the problem of dazzle; adjuncts like a stylet or gum elastic bougie have to be used at the outset to fix the softening problem; alternative methods to exhaled CO2 detection, such as the syringe aspiration technique, to confirm the proper tube placement, should be available.