ETCO2 Level Research Articles

Development of artificial intelligence-driven biosignal-sensitive cardiopulmonary resuscitation robot

Aim of the studyWe evaluated whether an artificial intelligence (AI)-driven robot cardiopulmonary resuscitation (CPR) could improve hemodynamic parameters and clinical outcomes. MethodsWe developed an AI-driven CPR robot which utilizes an integrated feedback system with an AI model predicting carotid blood flow (CBF). Twelve pigs were assigned to the AI robot group (n = 6) and the LUCAS 3 group (n = 6). They underwent 6 min of CPR after 7 min of ventricular fibrillation. In the AI robot group, the robot explored for the optimal compression position, depth and rate during the first 270-second period, and continued CPR with the optimal setup during the next 90-second period and beyond. The primary outcome was CBF during the last 90-second period. The secondary outcomes were coronary perfusion pressure (CPP), end-tidal carbon dioxide level (ETCO2) and return of spontaneous circulation (ROSC). ResultsThe AI model’s prediction performance was excellent (Pearson correlation coefficient = 0.98). CBF did not differ between the two groups [estimate and standard error (SE), −23.210 ± 20.193, P = 0.250]. CPP, ETCO2 level and rate of ROSC also did not show difference [estimate and SE, −0.214 ± 7.245, P = 0.976 for CPP; estimate and SE, 1.745 ± 3.199, P = 0.585 for ETCO2; 5/6 (83.3%) vs. 4/6 (66.7%), P = 1.000 for ROSC). ConclusionThis study provides proof of concept that an AI-driven CPR robot in porcine cardiac arrest is feasible. Compared to a LUCAS 3, an AI-driven CPR robot produced comparable hemodynamic and clinical outcomes.

Tracheal injury diagnosed by a sudden increase in end-tidal carbon dioxide levels during mediastinoscopic subtotal esophagectomy: a case report

BackgroundMediastinoscopic surgery for esophageal cancer facilitates early postoperative recovery. However, it can occasionally cause serious complications. Here, we present the case of a patient with a tracheal injury diagnosed by a sudden increase in end-tidal carbon dioxide (EtCO2) during mediastinoscopic subtotal esophagectomy.Case presentationA 52-year-old man diagnosed with esophageal cancer was scheduled to undergo mediastinoscopic subtotal esophagectomy. During the mediastinoscopic procedure, the EtCO2 level suddenly increased above 200 mmHg, and the blood pressure dropped below 80 mmHg. We immediately asked the operator to stop insufflation and found a tracheal injury on the right side of the trachea near the carina by bronchoscopy. The endotracheal tube was replaced with a double-lumen tube, and the trachea was repaired via right thoracotomy. There were no further intraoperative complications. After surgery, the patient was extubated and admitted to the intensive care unit.ConclusionsMonitoring EtCO2 levels and close communication with the operator is important for safely managing sudden tracheal injury during mediastinoscopic esophagectomy.

Diagnostic accuracy of using capnography in verification of nasogastric tube placement among adult patients in hospital settings: Protocol of a diagnostic study.

To determine the diagnostic accuracy of end-tidal carbon dioxide (ETCO2) detection using capnography for verifying the correct placement of nasogastric tubes (NGTs) among adult patients in hospital settings. A prospective observational diagnostic study will be conducted. Patients ≥ 18-year-old and requiring the insertion of an NGT will be recruited using a convenience sampling method from 39 general medical and geriatric wards, intensive care units, accident and emergency departments, and subacute/rehabilitation/infirmary wards in 21 acute or subacute/convalescent/extended care hospitals. ETCO2 detection by sidestream capnography, which indicates an airway intubation of an NGT when a capnogram waveform or an ETCO2 level > 10mmHg (1.33 kPa) occurs, will serve as the index test. The reference standards will be the X-ray performed and pH value of gastric aspiration (pH ≤ 5.5) after the index test. Each participant will be included only once. Sensitivity, specificity, positive predictive value, negative predictive value, and area under the receiver operating characteristic curve of capnography will be calculated to assess the diagnostic performance of capnography. The variability in diagnostic accuracy in participants with different characteristics will be explored by using chi-squared or Fisher's exact tests. The time spent and the cost of the tests will be compared using the paired t-test. All statistical tests will be two-sided with a level of significance set at 0.05. This study will provide evidence on the diagnostic accuracy of capnography in verifying NGT placement and its applicability to patients in hospitals settings, since this evidence is limited in the current literature. In addition, it will help identify the optimal combination of tests in verifying the correct placement of NGTs and inform the update of clinical practice guidelines and stakeholders' decisions on the adoption of ETCO2 detection as a routine method for verifying NGT placement. ClinicalTrials.gov ID: NCT05817864.

Association between intraoperative end-tidal carbon dioxide and postoperative organ dysfunction in major abdominal surgery: A cohort study.

Data on the effects of intraoperative end-tidal carbon dioxide (EtCO2) levels on postoperative organ dysfunction are limited. Thus, this study was designed to investigate the relationship between the intraoperative EtCO2 level and postoperative organ dysfunction in patients who underwent major abdominal surgery under general anesthesia. We conducted a cohort study involving patients who underwent major abdominal surgery under general anesthesia at Kyoto University Hospital. We classified those with a mean EtCO2 of less than 35 mmHg as low EtCO2. The time effect was determined as the minutes when the EtCO2 value was below 35 mmHg, whereas the cumulative effect was evaluated by measuring the area below the 35-mmHg threshold. The outcome was postoperative organ dysfunction, defined as a composite of at least one organ dysfunction among acute renal injury, circulatory dysfunction, respiratory dysfunction, coagulation dysfunction, and liver dysfunction within 7 days after surgery. Of the 4,171 patients, 1,195 (28%) had low EtCO2, and 1,428 (34%) had postoperative organ dysfunction. An association was found between low EtCO2 and increased postoperative organ dysfunction (adjusted risk ratio, 1.11; 95% confidence interval [CI], 1.03-1.20; p = 0.006). Additionally, long-term exposure to EtCO2 values of less than 35 mmHg (≥224 min) was associated with postoperative organ dysfunction (adjusted risk ratio, 1.18; 95% CI, 1.06-1.32; p = 0.003) and low EtCO2 severity (area under the threshold) (adjusted risk ratio, 1.13; 95% CI, 1.02-1.26; p = 0.018). Intraoperative low EtCO2 of below 35 mmHg was associated with increased postoperative organ dysfunction.

A Study to Correlate the ETCO2 and ABG in Predicting Metabolic Acidosis Among Patient on Mechanical Ventilation in Intensive Care Unit

Background: Capnography is an essential instrument for tracking metabolic and respiratory activity. According to the the ETCO2 level to predict metabolic acidosis with patient with mechanical ventilation admitted in ICU. Purpose: The purpose of current study was to predict the metabolic acidosis among patient on mechanical ventilator support. Materials and methods; A study was descriptive-analytical study design, was conducted in the host institution of Saveetha Medical College and Hospitals. There were 60 samples in ICU using purposive sampling techniques on the inclusion criteria within 24 hours of admission. In ICU collect data from every intubated patient with mechanical ventilator support along with ETCO2 probe connecting to the Endotracheal tube, Monitoring capnography values and comparison with the ABG values to predict metabolic acidosis. Results: Out of 60 samples with respect to capnography with EtCO2 the mean score of Bicarbonate level among patients with metabolic acidosis was 21.97±3.37 and the mean score of ETCO2 was 44.70±7.24. The calculated Karl Pearson’s Correlation value of r = -0.303 shows a negative correlation which was found to be statistically significant at p

Effect of end-tidal carbon dioxide level on the optic nerve sheath diameter measured by transorbital ultrasonography in anesthetized pediatric patients: A randomized trial.

Intraoperative hypercapnia and hypocapnia are common during pediatric anesthesia, and the cerebral blood flow and intracranial pressure may be affected by the partial pressure of arterial carbon dioxide. Transorbital ultrasound measurement of the optic nerve sheath diameter is a simple and non-invasive method for intracranial pressure assessment. The objective of this study was to evaluate the effect of end-tidal carbon dioxide (ET CO2 ) on optic nerve sheath diameter in a healthy anesthetized pediatric population. Pediatric patients scheduled for elective surgery under general anesthesia and mechanical ventilation in the supine position were enrolled and divided into four subgroups; age<2years, 2-6years, 6-12years, and 12-18years. Mechanical ventilation was adjusted to achieve target ET CO2 levels in a randomized sequence (40-35-45-40mmHg or 40-45-35-40mmHg). Three minutes after reaching each target ET CO2 level, transorbital ultrasound images of optic nerve sheath diameter were obtained and analyzed. The primary outcome was the optic nerve sheath diameter at each ET CO2 level. Sixty-four pediatric patients were enrolled and analyzed. At ET CO2 =40mmHg, the optic nerve sheath diameter was 5.6±0.6mm, 6.4±0.5mm, 6.8±0.6mm, and 7.1±0.5mm in children aged <2years, 2-6years, 6-12years, and 12-18years, respectively. The overall percent decreases in the optic nerve sheath diameter was -5.6±-4.3% (95% CI; -6.7 to -4.5%) at ET CO2 =35mmHg while the overall percent increases of optic nerve sheath diameter (ONSD) was 4.9±5.1% (95% CI; 3.6 to 6.1%) at ET CO2 =45mmHg compared with those at ET CO2 =40mmHg. Spearman rank correlation analysis indicated that there were weak to moderate correlation between ET CO2 and the optic nerve sheath diameter (correlation coefficient [p-value]=.355 [.004], .318 [.014], .373 [<.001], and .420 [<.001] in children aged <2years, 2-6years, 6-12years, and 12-18years, respectively). The optic nerve sheath diameter measured by transorbital ultrasound showed rapid reactivity from ET CO2 35 to 45mmHg in healthy pediatric patients under inhalation general anesthesia.

How to avoid rapid carbon dioxide changes at the start of veno-venous extracorporeal membrane oxygenation: Role of end-tidal CO2 monitoring.

Background: Venovenous ECMO is a lifesaving technique for patients with severe respiratory failure. Management of carbon dioxide (CO2) levels at ECMO start is crucial, as recent studies found an association between rapid CO2 shifts and increased incidence of neurological complications.Purpose: To describe the role of end tidal CO2 (etCO2) monitoring at the ECMO start to minimize carbon dioxide shifts.Research design: Retrospective cohort study.Methods: We performed a retrospective analysis of patients who started venovenous ECMO support at our institution between 2011 and 2021. We analysed the minute-by-minute variations of etCO2, ventilatory parameters and arterial blood gas before and after the ECMO start.Results: 36 patients with a complete dataset of parameters were included. After the ECMO start, minute ventilation was progressively reduced from 10.8±;3.3 to 2.9±1.2 L/min (p<0.001). etCO2 did not vary significantly (baseline 37±10 vs 35±9 mmHg 20 minutes after ECMO start, p = 0.36). Despite a stable etCO2 level, a mild drop of arterial CO2 tension (9.5 mmHg, corresponding to a 18% change) was recorded at the first ABG sampled after the ECMO start. No patient developed neurological complications after the ECMO commencement.Conclusion: etCO2 monitoring during ECMO start is feasible and allows to adjust gas flow and ventilator settings to limit changes in arterial CO2 levels.

Clinical prediction rule of termination of resuscitation for out-of-hospital cardiac arrest patient with pre-hospital defibrillation given.

To derive a clinical prediction rule of termination of resuscitation (TOR) for out-of-hospital cardiac arrest (OHCA) with pre-hospital defibrillation given. This was a retrospective multicenter cohort study performed in three emergency departments (EDs) of three regional hospitals from 1/1/2012 to 31/12/2018. Patients of OHCA aged ≥18years old were included. Those with post-mortem changes, return of spontaneous circulation and receiving no resuscitation in EDs were excluded. A TOR rule was derived by logistic regression analysis based on demographics and end-tidal carbon dioxide level of included subjects with pre-hospital defibrillation given. There were 447 included patients had received pre-hospital defibrillation, in which 148 had return of spontaneous circulation (ROSC), with 22 survived to discharge (STD). Independent predictors for death on or before ED arrival (no ROSC) included EMS call to ED time>20min and ETCO2 level<20mmHg from first three sets. A 2-criteria rule predicting death on or before ED arrival by fulfilling both of the independent predictors had a specificity of 0.95 (95% CI 0.90-0.98) and positive predictive value (PPV) of 0.95 (95% CI 0.90-0.98), if 2nd set of ETCO2 was used. The positive likelihood ratio was 10.04 (95% CI 4.83-20.89). The 2-criteria TOR rule for OHCA patients with pre-hospital defibrillation had a high specificity and PPV for predicting death on or before ED arrival.

Use of an end-tidal carbon dioxide-guided algorithm during cardiopulmonary resuscitation improves short-term survival in paediatric swine

AimTo evaluate an algorithm that uses an end-tidal carbon dioxide (ETCO2) target of ≥ 30 torr to guide specific changes in chest compression rate and epinephrine administration during cardiopulmonary resuscitation (CPR) in paediatric swine. MethodsSwine underwent asphyxial cardiac arrest followed by resuscitation with either standard or ETCO2-guided algorithm CPR. The standard group received chest compressions at a rate of 100/min and epinephrine every 4 min during advanced life support consistent with the American Heart Association paediatric resuscitation guidelines. In the ETCO2-guided algorithm group, chest compression rate was increased by 10 compressions/min for every minute that the ETCO2 was < 30 torr, and the epinephrine administration interval was decreased to every 2 min if the ETCO2 remained < 30 torr. Short-term survival and physiologic data during active resuscitation were compared. ResultsShort-term survival was significantly greater in the ETCO2-guided algorithm CPR group than in the standard CPR group (16/28 [57.1%] versus 4/28 [14.3%]; p = 0.002). Additionally, the algorithm group had higher predicted mean ETCO2, chest compression rate, diastolic and mean arterial pressure, and myocardial perfusion pressure throughout resuscitation. Swine in the algorithm group also exhibited significantly greater improvement in diastolic and mean arterial pressure and cerebral perfusion pressure after the first dose of epinephrine than did those in the standard group. Incidence of resuscitation-related injuries was similar in the two groups. ConclusionsUse of a resuscitation algorithm with stepwise guidance for changes in the chest compression rate and epinephrine administration interval based on a goal ETCO2 level improved survival and intra-arrest hemodynamics in this porcine cardiac arrest model.

Mildly Reduced Doses of Adrenaline Do Not Affect Key Hemodynamic Parameters during Cardio-Pulmonary Resuscitation in a Pig Model of Cardiac Arrest.

Adrenaline is recommended for cardiac arrest resuscitation, but its effectiveness has been questioned recently. Achieving return of spontaneous circulation (ROSC) is essential and is obtained by increasing coronary perfusion pressure (CPP) after adrenaline injection. A threshold as high as 35 mmHg of CPP may be necessary to obtain ROSC, but increasing doses of adrenaline might be harmful to the brain. Our study aimed to compare the increase in CPP with reduced doses of adrenaline to the recommended 1 mg dose in a pig model of cardiac arrest. Fifteen domestic pigs were randomized into three groups according to the adrenaline doses: 1 mg, 0.5 mg, or 0.25 mg administered every 5 min. Cardiac arrest was induced by ventricular fibrillation; after 5 min of no-flow, mechanical chest compression was resumed. The Wilcoxon test and Kruskal–Wallis exact test were used for the comparison of groups. Fisher’s exact test was used to compare categorical variables. CPP, EtCO2 level, cerebral, and tissue near-infrared spectroscopy (NIRS) were measured. CPP was significantly lower in the 0.25 mg group 90 s after the first adrenaline injection: 28.9 (21.2; 35.4) vs. 53.8 (37.8; 58.2) in the 1 mg group (p = 0.008), while there was no significant difference with 0.5 mg 39.6 (32.7; 52.5) (p = 0.056). Overall, 0.25 mg did not achieve the threshold of 35 mmHg. EtCO2 levels were higher at T12 and T14 in the 0.5 mg than in the standard group: 32 (23; 35) vs. 19 (16; 26) and 26 (20; 34) vs. 19 (12; 22) (p < 0.05). Cerebral and tissue NIRS did not show a significant difference between the three groups. CPP after 0.5 mg boluses of adrenaline was not significantly different from the recommended 1 mg in our model of cardiac arrest.

Pulse oximetry waveform: A non-invasive physiological predictor for the return of spontaneous circulation in cardiac arrest patients ---- A multicenter, prospective observational study

ObjectiveThis study aimed to investigate the predictive value of pulse oximetry plethysmography (POP) for the return of spontaneous circulation (ROSC) in cardiac arrest (CA) patients. MethodsThis was a multicenter, observational, prospective cohort study of patients hospitalized with cardiac arrest at 14 teaching hospitals cross China from December 2013 through November 2014. The study endpoint was ROSC, defined as the restoration of a palpable pulse and an autonomous cardiac rhythm lasting for at least 20 minutes after the completion or cessation of CPR. Results150 out-of-hospital cardiac arrest (OHCA) patients and 291 in-hospital cardiac arrest (IHCA) patients were enrolled prospectively. ROSC was achieved in 20 (13.3%) and 64 (22.0%) patients in these cohorts, respectively. In patients with complete end-tidal carbon dioxide (ETCO2) and POP data, patients with ROSC had significantly higher levels of POP area under the curve (AUCp), wave amplitude (Amp) and ETCO2 level during CPR than those without ROSC (all p < 0.05). Pairwise comparison of receiver operating characteristic (ROC) curve analysis indicated no significant difference was observed between ETCO2 and Amp (p = 0.204) or AUCp (p = 0.588) during the first two minutes of resuscitation. ConclusionPOP may be a novel and effective method for predicting ROSC during resuscitation, with a prognostic value similar to ETCO2 at early stage.

Cardiopulmonary Functions in Dogs under Propofol, Ketamine and Isoflurane Anaesthesia Premedicated with Glycopyrrolate, Dexmedetomidine and Butorphanol

Background: The study was conducted to evaluate the cardiopulmonary functions in dog under propofol, ketamine and isoflurane anaesthesia premedicated with dexmedetomidine and butorphanol.Methods: Four groups of dogs (A,B,C and D) comprising of six animals in each groups were premedicated with glycopyrrolate @ 0.01 mg/kg, dexmedetomidine @5ìg/kg IV and Butorphanol @ 0.1mg/kg IV. Induction was done with propofol (A and B) and with ketamine (C and D). The anaesthesia was maintained with isoflurane (A and C), propofol (B) and ketamine (D). The cardiopulmonary functions were recorded at 0 minute (before premedication) and 20 minutes, 40 minutes and 60 minutes. Result: The heart rate decreased significantly in Group B while there was a significant gradual increase in heart rate in Group D. A significant decrease in respiratory rate was observed in all the groups with a lowest value in group D. The systolic pressure decreased significantly in Group A, B and C but in Group D, the systolic pressure decreased initially at 20 minute. The diastolic pressure decreased significantly in Group A and Group B and but in group D, the diastolic pressure decreased at 20 minute. A significant decrease in mean arterial pressure was recorded in Group A, B and C. In Group D, a decrease in the mean arterial pressure was noticed at 20 minute. The SpO2 level remained near the base line values with slight variation in Group A and C where as the values remained at lower level from the base line value in Group B and D. The EtCO2 level showed non-significant changes in Group A and C. In Group B and D, the EtCO2 levels increased non-significantly with the highest value recorded in Group D. The ECG parameters remained within the normal limit with slight variation according to the heart rate.

Norepinephrine with dopamine infusion on the end-tidal carbon dioxide (ETco2) pressure in patients with septic shock.

Background:Septic shock is a critical medical condition and immediate intervention is required as well as hemodynamic stability using fluid and vasopressor. Direct relationship between changes in ETco2 and changes in the cardiac output. We evaluated the study by comparing the effect of using norepinephrine or dopamine on ETco2 of patients with septic shock.Methods:A clinical trial study was performed on 138 patients with primary diagnosis of septic shock. 70 patients received norepinephrine and 68 patients received dopamine. Patients' end tidal carbon dioxide (ETco2), mean arterial pressure (MAP), pulse rate (PR), arterial blood gas (ABG) levels in two groups were measured and compared at baseline and after 30 and 120 minutes after inotrope infusion. Variables were compared by means of an unpaired student t-test, an unadjusted chi-square test.Results:138 patients, 70 treated with norepinephrine infusion and 68 with dopamine infusion were included in the study. ETco2 level significantly increased within 120 minutes of treatment in the norepinephrine group (31.10±9.65) compared to the dopamine group (23.71±9.66) (P=0.001). MAP significantly decreased in the group of norepinephrine 30 minutes after treatment (71.71±20.460) (P=0.014) and pulse rate also significantly decreased in the norepinephrine group compared to the dopamine group in 30 minutes (98.07±10.63 vs 106.43±13.54) and 120 minutes (91.15±6.18 vs 103.51±2057) after treatment (P=0.001).Conclusion:Tissue perfusion and fluid responsiveness of the shock in the norepinephrine group showed improvement. Using ETco2 as a measure for determining volume assessment in patients undergoing mechanical ventilation by septic shock is applicable.

Ventilation Is an Important Confounding Variable When End-Tidal Carbon Dioxide Is Used to Help Guide Cardiopulmonary Resuscitation

Ventilation Is an Important Confounding Variable When End-Tidal Carbon Dioxide Is Used to Help Guide Cardiopulmonary Resuscitation

Correlation between end-tidal carbon dioxide and the degree of compression of heart cavities measured by transthoracic echocardiography during cardiopulmonary resuscitation for out-of-hospital cardiac arrest

BackgroundThe concept of personalized cardiopulmonary resuscitation (CPR) requires a parameter that reflects its hemodynamic efficiency. While intra-arrest ultrasound is increasingly implemented into the advanced life support, we realized a pre-hospital clinical study to evaluate whether the degree of compression of the right ventricle (RV) and left ventricle (LV) induced by chest compressions during CPR for out-of-hospital cardiac arrest (OHCA) and measured by transthoracic echocardiography correlates with the levels of end-tidal carbon dioxide (EtCO2) measured at the time of echocardiographic investigation.MethodsThirty consecutive patients resuscitated for OHCA were included in the study. Transthoracic echocardiography was performed from a subcostal view during ongoing chest compressions in all of them. This was repeated three times during CPR in each patient, and EtCO2 levels were registered. From each investigation, a video loop was recorded. Afterwards, maximal and minimal diameters of LV and RV were obtained from the recorded loops and the compression index of LV (LVCI) and RV (RVCI) was calculated as (maximal − minimal/maximal diameter) × 100. Maximal compression index (CImax) defined as the value of LVCI or RVCI, whichever was greater was also assessed. Correlations between EtCO2 and LVCI, RVCI, and CImax were expressed as Spearman’s correlation coefficient (r).ResultsEvaluable echocardiographic records were found in 18 patients, and a total of 52 measurements of all parameters were obtained. Chest compressions induced significant compressions of all observed cardiac cavities (LVCI = 20.6 ± 13.8%, RVCI = 34.5 ± 21.6%, CImax = 37.4 ± 20.2%). We identified positive correlation of EtCO2 with LVCI (r = 0.672, p < 0.001) and RVCI (r = 0.778, p < 0.001). The strongest correlation was between EtCO2 and CImax (r = 0.859, p < 0.001). We identified that a CImax cut-off level of 17.35% predicted to reach an EtCO2 level > 20 mmHg with 100% sensitivity and specificity.ConclusionsEvaluable echocardiographic records were reached in most of the patients. EtCO2 positively correlated with all parameters under consideration, while the strongest correlation was found between CImax and EtCO2. Therefore, CImax is a candidate parameter for the guidance of hemodynamic-directed CPR.Trial registrationClinicalTrial.gov, NCT03852225. Registered 21 February 2019 - Retrospectively registered.

A Systematic Approach to Ventilator Management for the Pediatric Patient during Air Medical Transport

A checklist was developed to improve the ventilator management of pediatric patients for AeroCare. Reduce the percentage of patients outside recommended parameters (no bag-valve mask use, SpO2 level > 90%, and EtCO2 level >35 and <50 mmHg) from 41.3% to 20% within seven months. The checklist was developed based on recommended guidelines. After checklist orientation, its effectiveness was analyzed via chart review for patients meeting inclusion criteria (> 5 kg and < 18 years) from July 2018 to January 2019. Parameters identified in the aim statement were used to evaluate effectiveness. Post-transport, a Likert survey concerning the value of the checklist was distributed. Significant improvements in pediatric ventilator management were noted when teams used the checklist. The rate outside of aim parameters was reduced significantly from 41.3% (N = 92, June 2012 to May 2018 pre-intervention) to 10% (N = 20, July 2018 to January 2019 post-intervention) after the improvement action was implemented (X2= 7.01, p = .008). The 5-point Likert survey results (N = 38, 4.68 +/- .57) supported teams' improved comfort post-checklist implementation. The checklist improved ventilator management proficiency of pediatric patients and the comfort level of AeroCare teams providing the care.

End-tidal carbon dioxide underestimates plasma carbon dioxide during emergent trauma laparotomy leading to hypoventilation and misguided resuscitation: A Western Trauma Association Multicenter Study.

End-tidal carbon dioxide (ETCO2) is routinely used during elective surgery to monitor ventilation. The role of ETCO2 monitoring in emergent trauma operations is poorly understood. We hypothesized that ETCO2 values underestimate plasma carbon dioxide (pCO2) values during resuscitation for hemorrhagic shock. Multicenter trial was performed analyzing the correlation between ETCO2 and pCO2 levels. Two hundred fifty-six patients resulted in 587 matched pairs of ETCO2 and pCO2. Correlation between these two values was very poor with an R of 0.04. 40.2% of patients presented to the operating room acidotic and hypercarbic with a pH less than 7.30 and a pCO2 greater than 45 mm Hg. Correlation was worse in patients that were either acidotic or hypercarbic. Forty-five percent of patients have a difference greater than 10 mm Hg between ETCO2 and pCO2. A pH less than 7.30 was predictive of an ETCO2 to pCO2 difference greater than 10 mm Hg. A difference greater than 10 mm Hg was predictive of mortality independent of confounders. Nearly one half (45%) of patients were found to have an ETCO2 level greater than 10 mm Hg discordant from their PCO2 level. Reliance on the discordant values may have contributed to the 40% of patients in the operating room that were both acidotic and hypercarbic. Early blood gas analysis is warranted, and a lower early goal of ETCO2 should be considered. Therapeutic, level IV.

Relationship between hemodynamic parameters and severity of ischemia-induced left ventricular wall thickening during cardiopulmonary resuscitation of consistent quality.

Ischemia-induced left ventricular (LV) wall thickening compromises the hemodynamic effectiveness of cardiopulmonary resuscitation (CPR). However, accurate assessment of the severity of ischemia-induced LV wall thickening during CPR is challenging. We investigated, in a swine model, whether hemodynamic parameters, including end-tidal carbon dioxide (ETCO2) level, are linearly associated with the severity of ischemia-induced LV wall thickening during CPR of consistent quality. We retrospectively analyzed 96 datasets for ETCO2 level, arterial pressure, LV wall thickness, and the percent of measured end-diastolic volume (%EDV) relative to EDV at the onset of ventricular fibrillation from eight pigs. Animals underwent advanced cardiovascular life support based on resuscitation guidelines. During CPR, LV wall thickness progressively increased while %EDV progressively decreased. Systolic and diastolic arterial pressure and ETCO2 level were significantly correlated with LV wall thickness and %EDV. Linear mixed effect models revealed that, after adjustment for significant covariates, systolic and diastolic arterial pressure were not associated with LV wall thickness or %EDV. ETCO2 level had a significant linear relationship with %EDV (P = 0.004). However, it could explain only 28.2% of the total variance of %EDV in our model. In conclusion, none of the hemodynamic parameters examined in this study appeared to provide sufficient information on the severity of ischemia-induced LV wall thickening.

Sex differences in cerebral haemodynamics across the physiological range of PaCO2

Objective: Cerebral blood flow (CBF) is influenced by changes in arterial CO2 (PaCO2). Recently, cerebral haemodynamic parameters were demonstrated to follow a four parameter logistic curve offering simultaneous assessment of dCA and CO2 vasoreactivity. However, the effects of sex on cerebral haemodynamics have yet to be described over a wide range of PaCO2. Approach: CBF velocity (CBFV, transcranial Doppler), blood pressure (BP, Finometer) and end-tidal CO2 (EtCO2, capnography) were measured in healthy volunteers at baseline, and in response to hypo- (−5 mmHg and −10 mmHg below baseline) and hypercapnia (5% and 8% CO2), applied in random order. Main results: Forty-five subjects (19 male, 26 female, mean age 37.5 years) showed significant differences between males and females in CBFV (50.9 ± 10.4 versus 61.5 ± 12.3 cm · s−1, p = 0.004), EtCO2 (39.2 ± 2.8 versus 36.9 ± 3.0 mmHg, p = 0.005), RAP (1.16 ± 0.23 versus 0.94 ± 0.40 mmHg cm · s−1, p = 0.005) and systolic BP (125.2 ± 8.0 versus 114.6 ± 12.4 mmHg, p = 0.0372), respectively. Significant differences between sexes were observed in the four logistic parameters: ymin, ymax, k (exponential coefficient) and x (EtCO2 level) across the haemodynamic variables. Significant differences included the CBFV-EtCO2 and ARI-EtCO2 relationship; ARImin (p = 0.036) and CBFVmax (p = 0.001), respectively. Furthermore, significant differences were observed for both CrCPmin (p = 0.045) and CrCPmax (p = 0.005) and RAPmin (p < 0.001) and RAPmax (p < 0.001). Significance: This is the first study to examine sex individually within the context of a multi-level CO2 protocol. The demonstration that the logistic curve parameters are influenced by sex, highlights the need to take into account sex differences between participants in both physiological and clinical studies.

Sustained inflations versus UK standard inflations during initial resuscitation of prematurely born infants in the delivery room: a study protocol for a randomised controlled trial

BackgroundMany infants born at less than 34 weeks of gestational age will require resuscitation in the delivery suite. Yet, different resuscitation techniques are specified in different national guidelines, likely reflecting a limited evidence base. One difference is the length of mechanical inflation initially delivered to infants either via a facemask or endotracheal tube. Some guidelines specify short inflations delivered at rates of 40–60/min, others recommend initial inflations lasting 2–3 s or sustained inflations lasting for ≥ 5 s for initial resuscitation. Research has shown that tidal volumes > 2.2 mL/kg (the anatomical dead space) are seldom generated unless the infant’s respiratory effort coincides with an inflation (active inflation). When inflations lasting 1–3 s were used, the time to the first active inflation was inversely proportional to the inflation time. This trial investigates whether a sustained inflation or repeated shorter inflations is more effective in stimulating the first active inflation.MethodsThis non-blinded, randomised controlled trial performed at a single tertiary neonatal unit is recruiting 40 infants born at < 34 weeks of gestational age. A 15-s sustained inflation is being compared to five repeated inflations of 2–3 s during the resuscitation at delivery. A respiratory function monitor is used to record airway pressure, flow, expiratory tidal volume and end tidal carbon dioxide (ETCO2) levels. The study is performed as emergency research without prior consent and was approved by the NHS London-Riverside Research Ethics Committee. The primary outcome is the minute volume in the first minute of resuscitation with secondary outcomes of the time to the first active inflation and ETCO2 level during the first minute of recorded resuscitation.DiscussionThis is the first study to compare a sustained inflation to the current UK practice of five initial inflations of 2–3 s.Trial registrationClinicalTrials.gov, NCT02967562. Registered on 15 November 2016.