Objective:to evaluate the usefulness of capnography for the detection of metabolic changes in spontaneous breathing patients, in the emergency and intensive care settings. Methods:in-depth and structured bibliographical search in the databases EBSCOhost, Virtual Health Library, PubMed, Cochrane Library, among others, identifying studies that assessed the relationship between capnography values and the variables involved in blood acid-base balance. Results:19 studies were found, two were reviews and 17 were observational studies. In nine studies, capnography values were correlated with carbon dioxide (CO2), eight with bicarbonate (HCO3), three with lactate, and four with blood pH. Conclusions:most studies have found a good correlation between capnography values and blood biomarkers, suggesting the usefulness of this parameter to detect patients at risk of severe metabolic change, in a fast, economical and accurate way.

The latest guidelines identify capnography as an instrument used to assess bag-valve-mask ventilation during cardiopulmonary resuscitation (CPR). In this review, we analyzed the feasibility and reliability of capnography use with face mask ventilation during CPR maneuvers in adults and children. This systematic review was completed in December 2018; data for the study were obtained from the following databases: EBSCOhost, SCOPUS, PubMed, Índice Bibliográfico Español en Ciencias de la Salud (IBECS), TESEO, and Cochrane Library Plus. Two reviewers independently assessed the eligibility of the articles; we analyzed publications from different sources and identified studies that focused on the use of capnography with a face mask during CPR maneuvers in order to describe the capnometry value and its correlation with resuscitation outcomes and the assistance of professionals. A total of 888 papers were collected, and 17 papers were included that provided objective values for the use of capnography with a mask for ventilation. Four were randomized clinical trials (RCT) and the rest were observational studies. Four studies were completed in adults and 13 were completed in newborns. After the analysis of the papers, we recommended a capnographic level of C in adults and B in newborns. Despite the little evidence obtained, capnography has been demonstrated to facilitate the advanced clinical practice of mask ventilation in cardiopulmonary resuscitation, to be reliable in the early detection of heart rate increase in newborns, and to asses in-airway patency and lung aeration during newborn resuscitation.

There is still controversy today about the superiority of advanced versus basic airway management during CPR maneuvers. This uncertainty was announced in the most recent ILCOR guidelines, and it seems to be corroborated by a recent randomized trial comparing survival and neurological recovery from CPR in patients treated with bag-valve-mask (BVM) versus orotracheal intubation. 1 Although the possibility of using capnography within BVM or extraglottic devices has been indicated by the European Resuscitation Council, 2 it seems not to be common practice at the moment. In order to better understand the current state of the use of capnography with BVM ventilation during CPR, we have conducted a systematic review across various databases using the search: (capnography [MeSH]) AND (Cardiopulmonary resuscitation [MeSH]).Unfortunately, in our research, we only found 2 observational articles correlating capnography values with the results of CPR ( Fig. 1): one in adults 3 and another in newborns. 4 Both of them use qualitative devices in order to assess the quality of ventilation, recovery of spontaneous circulation, increase of heart rate in newborns or find a correlation between the values with survival after CPR. On the one hand, Nakatani et al. 3 showed that in adults ventilated with BVM, there was a correlation between superior levels of capnometry detection and ROSC in 15% of patients in the group with CO2 values <0,5% (<4 mmHg) and in 43% of patients who presented values >2% (>15 mmHg). On the other hand, in the newborn study, the early detection of an increase of capnometry occurred 10-20 s before an increase in heart rate was recorded by the electrocardiogram monitoring.In the literature review, there seems to be a small gap in the use of capnography during instrumental basic resuscitation. We did not find any high-quality randomized clinical trials comparing the capnography values obtained by basic versus advanced life support airway management nor regarding their use to improve the quality of maneuvers. Preliminary findings suggest that with capnography monitoring during BVM ventilation we can achieve and quantify the increased effectiveness of resuscitative efforts.Mask ventilation is difficult and requires good training or experience. In order to quantify the quality of ventilation with BVM, a good methodology could be to assess the ventilation within the capnography monitoring with a scale, as has been proposed by Lim and Nielsen 5 in the context of anesthesia. They establish a 4-level scale of ventilation quality based on the values obtained and the capnogram shape during capnography monitoring. It is interesting to note that in two decades no one else has done a study using quantitative capnography values to compare the difference between BVM ventilation and other advanced airway devices such as extraglottic devices in adults. We have just started a cluster- Fig. 1 -Flow-chart of information, according to the review stages. Resuscitation j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o...

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