End-tidal Carbon Dioxide Levels Research Articles

Comparison of Respiratory Effects between Dexmedetomidine and Propofol Sedation for Ultrasound-Guided Radiofrequency Ablation of Hepatic Neoplasm: A Randomized Controlled Trial.

Patient’s cooperation and respiration is necessary in percutaneous radiofrequency ablation (RFA) for hepatocellular carcinoma (HCC). We compared the respiratory patterns of dexmedetomidine and propofol sedation during this procedure. Participants were randomly allocated into two groups: the continuous infusions of dexmedetomidine-remifentanil (DR group) or the propofol-remifentanil (PR group). We measured the tidal volume for each patient’s respiration during one-minute intervals at five points and compared the standard deviation of the tidal volumes (SDvt) between the groups. Sixty-two patients completed the study. SDvt at 10 min was not different between the groups (DR group, 108.58 vs. PR group, 149.06, p = 0.451). However, SDvt and end-tidal carbon dioxide (EtCO2) level of PR group were significantly increased over time compared to DR group (p = 0.004, p = 0.021; ß = 0.14, ß = −0.91, respectively). Heart rate was significantly decreased during sedation in DR group (p < 0.001, ß = −2.32). Radiologist satisfaction was significantly higher, and the incidence of apnea was lower in DR group (p = 0.010, p = 0.009, respectively). Compared with propofol-remifentanil, sedation using dexmedetomidine-remifentanil provided a lower increase of the standard deviation of tidal volume and EtCO2, and also showed less apnea during RFA of HCC.

Prehospital End-Tidal CO2: A Superior Marker for Mortality Risk in the Acutely Injured Patient.

Emergency medical personnel must expeditiously triage acutely injured patients to the appropriate medical facility. Efficient and objective variables to facilitate this process and provide information to the receiving trauma center are needed. Currently, multiple variables are used to prognosticate injury severity and risk of mortality including vital signs, mental status, lactate, and base excess. We investigated the prehospital use of end-tidal carbon dioxide (ETCO2) as a noninvasive physiologic measure that can be obtained in the acutely injured patient. We performed a retrospective analysis of 557 acutely injured patients over 2years at a Level 1 trauma center. All patients arriving as trauma activations with ETCO2 measurements were included in analysis. End-tidal carbon dioxide measurements were categorized as low, normal, and high based on reference levels. Mortality was the primary outcome. Secondary receiver operator curves (ROC) for base excess, venous lactate, blood pressure, and venous pH were compared. We hypothesized ETCO2 levels would be able to predict mortality. End-tidal carbon dioxide levels conferred a mortality rate of 38%, 17.3%, and 2.9% for low, normal, and high, respectively (P < .001). Receiver operator curve analysis produced an area under the curve predictive value for ETCO2 (.748) which was superior to lactate (.660), SBP (.578), pH (.560), and base excess (.497). End-tidal carbon dioxide is a more sensitive and specific predictor of mortality in the acutely injured patient compared to venous lactate, base deficit, blood pressure, or venous pH. Additional studies are needed to determine if ETCO2 can be used as an effective prehospital adjunct to prevent mortality in acutely injured patients.

Polysomnography parameters as predictors of respiratory adverse events following adenotonsillectomy in children

The first-line treatment of obstructive sleep apnea syndrome in children is adenotonsillectomy, but this may result in perioperative respiratory adverse events (PRAEs). The primary aim of this study is to examine whether the McGill oximetry score (MOS) and other polysomnography parameters can predict major PRAEs following adenotonsillectomy. We secondarily evaluated the MOS interrater reliability and correlation with other polysomnography parameters. This retrospective study included all children aged 0-18 years who underwent preoperative polysomnography between June 2010 and January 2016 prior to adenotonsillectomy at a tertiary pediatric institution. Oximetries from polysomnograms were assigned an MOS. Univariable and multivariable models for prediction of major PRAEs were constructed. MOS was correlated with polysomnography parameters and interrater reliability was evaluated. This study included 106 children; 15 had a major PRAE. A multivariable prediction model that combined MOS and age showed evidence for the ability to predict major PRAEs with an area under the receiver operating characteristic curve of 0.68 (95% confidence interval: 0.52, 0.84), whereby increased MOS and younger age were associated with PRAEs, but apnea-hypopnea index was not. MOS had excellent interrater reliability (κ = 0.95) and was highly correlated with oxygen saturation nadir and cumulative time percentage with oxygen saturation less than 90%. A prediction model including MOS and age may predict PRAEs following adenotonsillectomy. This suggests that nocturnal oximetry provides the most essential information of polysomnography measures to direct postoperative monitoring following adenotonsillectomy. Xiao L, Barrowman N, Momoli F, etal. Polysomnography parameters as predictors of respiratory adverse events following adenotonsillectomy in children. J Clin Sleep Med. 2021;17(11):2215-2223.

Multi-Parametric Evaluation of Cerebral Hemodynamics in Neonatal Piglets Using Non-Contrast-Enhanced Magnetic Resonance Imaging Methods.

Disruption of brain oxygen delivery and consumption after hypoxic-ischemic injury contributes to neonatal mortality and neurological impairment. Measuring cerebral hemodynamic parameters, including cerebral blood flow (CBF), oxygen extraction fraction (OEF), and cerebral metabolic rate of oxygen (CMRO2 ), is clinically important. Phase-contrast (PC), velocity-selective arterial spin labeling (VSASL), and T2 -relaxation-under-phase-contrast (TRUPC) are magnetic resonance imaging (MRI) techniques that have shown promising results in assessing cerebral hemodynamics in humans. We aimed to test their feasibility in quantifying CBF, OEF, and CMRO2 in piglets. Prospective. Ten neonatal piglets subacutely recovered from global hypoxia-ischemia (N=2), excitotoxic brain injury (N=6), or sham procedure (N=2). VSASL, TRUPC, and PC MRI acquired at 3.0 T. Regional CBF was measured by VSASL. Global CBF was quantified by both PC and VSASL. TRUPC assessed OEF at the superior sagittal sinus (SSS) and internal cerebral veins (ICVs). CMRO2 was calculated from global CBF and SSS-derived OEF. End-tidal carbon dioxide (EtCO2 ) levels of the piglets were also measured. Brain damage was assessed in tissue sections postmortem by counting damaged neurons. Spearman correlations were performed to evaluate associations among CBF (by PC or VSASL), OEF, CMRO2 , EtCO2 , and the pathological neuron counts. Paired t-test was used to compare OEF at SSS with OEF at ICV. Global CBF was 32.1 ± 14.9 mL/100 g/minute and 30.9 ± 8.3 mL/100 g/minute for PC and VSASL, respectively, showing a significant correlation (r=0.82, P < 0.05). OEF was 54.9 ± 8.8% at SSS and 46.1 ± 5.6% at ICV, showing a significant difference (P < 0.05). Global CMRO2 was 79.1 ± 26.2 μmol/100 g/minute and 77.2 ± 12.2 μmol/100 g/minute using PC and VSASL-derived CBF, respectively. EtCO2 correlated positively with PC-based CBF (r=0.81, P < 0.05) but negatively with OEF at SSS (r=-0.84, P < 0.05). Relative CBF of subcortical brain regions and OEF at ICV did not significantly correlate, respectively, with the ratios of degenerating-to-total neurons (P=0.30, P=0.10). Non-contrast MRI can quantify cerebral hemodynamic parameters in normal and brain-injured neonatal piglets. 1 TECHNICAL EFFICACY STAGE: 2.

Analysis of European Air Medical Evacuation Flights of Coronavirus Disease 2019 Patients

ObjectiveAs part of the humanitarian response to the coronavirus disease 2019 (COVID-19) pandemic, the German and French Armed Forces provided air transport for patients from overwhelmed regional hospitals in Italy and France. The objective of this study was to analyze the characteristics of the missions and the medical conditions of COVID-19 patients transported during an air medical evacuation on fixed wing aircraft in March and April 2020. MethodThis was a retrospective analysis of transport records as well as other documents for 58 COVID-19 patients requiring artificial ventilation. ResultsThe median age of the transported patients was 61.5 years, and 61% of them had preexisting medical conditions. They had been ventilated for a median of 5 days and experienced the first symptoms 18 days before transport. The patients flown out of France had less days of ventilation before flight, a lower end-tidal carbon dioxide level at the beginning of the flight, and a lower Charlson Comorbidity Index. There were also some differences between the ventilation and the flight level flown by the 2 air forces. ConclusionThe intensive care transport of ventilated COVID-19 patients requires highly qualified personnel and appropriate equipment and should be planned appropriately.

Effects of end-tidal carbon dioxide levels in patients undergoing direct revascularization for Moyamoya disease and risk factors associated with postoperative complications.

A history of transient ischemic attack, severity of disease, urinary output, hematocrit, hypocapnia, and hypotension during direct revascularization (superficial temporal artery to middle cerebral artery [STA-MCA]) in patients with Moyamoya disease (MMD) may lead to a poor prognosis, however, to our knowledge evidence for end-tidal carbon dioxide (ETCO2) targets is lacking. Within the ranges of standardized treatment, the article was primarily designed to study the risk factors associated with the neurologic outcomes during STA-MCA for MMD especially including ETCO2 ranges and the duration in different groups. The primary goals of this study were to investigate the risk factors for neurologic deterioration and explore the association between ETCO2 ranges and neurologic outcome during general anesthesia for STA-MCA.This retrospective observational study included 56 consecutively adult Moyamoya patients who underwent STA-MCA under general anesthesia between January 2015 and August 2019. ETCO2 was summarized per patient every 5 minutes. Clinical outcome was assessed with clinical presentation, computed tomography findings, magnetic resonance imaging findings, cerebral angiography, and the modified Rankin Scale scores at discharge as main outcome measure. The outcomes were also compared for the duration of surgery, anesthesia, and the length of stay.A total of 56 patients were studied, all patients had comprehensive ETCO2 measurements. The incidence of postoperative complications was 44.6% (25/56). There was no association between age, sex, hypertension, diabetes, smoking history, drinking history, sevoflurane use, invasive arterial blood pressure monitoring, combined encephalomyosynangiosis and postoperative complications. Duration of surgery (P = .04), anesthesia (P = .036), hospital stay (P = .023) were significant correlates of postoperative complications. In the multiple logistic regression model, they were not the significant predictors. The ETCO2 ranges and the length of time in different groups within the current clinical setting was not associated with postoperative complications (P > .05).Within a standardized intraoperative treatment strategy, we found that postoperative complications had no significant correlation with sex, age, hypertension, diabetes, smoking history, drinking history, invasive arterial blood pressure monitoring, combined encephalomyosynangiosis, or sevoflurane use. Further, hypocapnia and hypercapnia during STA-MCA were not found to be associated with postoperative complications in patients with MMD.

Investigating the Effects of Protective Face Masks on the Respiratory Parameters of Children in the Postanesthesia Care Unit During the COVID-19 Pandemic

PurposeThe purpose of this study was to investigate the effect of protective face mask usage during the postoperative period on carbon dioxide retention in children during the COVID-19 pandemic. DesignThis study was designed as a prospective, randomized trial including 40 ASA I–II patients aged 3 to 10 years who were scheduled for elective surgery. MethodsPatients were randomly allocated to two groups. The first group (group 1) received O2 treatment over the protective face mask. In the second group (group 2), the protective face mask was worn over the O2 delivery system. Heart rate, oxygen saturation (SPO2) level, end-tidal carbon dioxide (EtCO2) level, and respiratory rate were measured using a patient monitor at 0, 5, 10, 15, 30, and 45 minutes and recorded. The primary outcome of the study was the determination of the EtCO2 levels, which were used to assess the safety of the mask in terms of potential carbon dioxide retention. FindingsNone of the participants’ SPO2 levels fell below 92% while wearing masks. There was no statistically significant difference between the groups in terms of EtCO2, heart rate, SPO2, and respiratory rate (P > .05). ConclusionsDuring the COVID-19 pandemic, protective surgical face masks can be used safely in the postoperative period for pediatric patients aged 3 to 10 years.

Respiratory monitoring during less invasive surfactant administration in the delivery suite

BackgroundOn the neonatal unit less invasive surfactant administration (LISA) reduces BPD and the need for mechanical ventilation. AimsTo evaluate the feasibility of LISA in the delivery suite and to undertake respiratory function physiological monitoring before and after LISA. Study designA prospective, observational cohort study was undertaken. A LISA simulation training programme was delivered. Then, LISA was undertaken in infants with respiratory distress maintained on continuous positive airway pressure (CPAP) in the delivery suite using videolaryngoscopic guidance without sedation. SubjectsThirty-eight infants with a median (IQR) gestational age of 31 + 5 weeks (30+3–33+4) and birth weight of 1.61 (1.42–1.90) kg had LISA in the delivery suite. Outcome measuresAdverse effects of LISA and whether LISA resulted in changes in tidal and minute volumes, end tidal carbon dioxide (EtCO2) levels and the inspired oxygen concentration (FiO2). ResultsRespiratory function monitoring was available for 34 of the infants. LISA occurred at a median (IQR) interval of 18 (15–29) minutes after birth. The most common adverse events were desaturation (44.7%) and surfactant reflux (39.5%), both responded to either temporary suspension of LISA or slowing the speed of surfactant administration. Following LISA, there was a significant reduction in respiratory rate 2 min later (p < 0.001) and in the FiO2 2 h later (p < 0.001). ConclusionsLISA is feasible in the delivery suite after appropriate training of staff. It can be undertaken without serious adverse effects and results in a reduction in respiratory distress and improvement in oxygenation.

The PaCO2-ETCO2 gradient in pre-hospital intubations of all aetiologies from a single UK helicopter emergency medicine service 2015-2018.

Control of the arterial partial pressure of carbon dioxide (PaCO2) is important in the ventilated patient. End-tidal carbon dioxide (ETCO2) levels are often used as a proxy, but are clinically limited. The difference between the PaCO2 and ETCO2 has been suggested to be 0.5-1.0 kPa. However, this has not been consistently reflected in the physiologically unstable pre-hospital patient. This study aims to elucidate the PaCO2-ETCO2 gradient for pre-hospital intubated patients. This was a retrospective, cohort study using data identified from the HEMSbase 2 database (Feb 2015-Nov 2018). Patients were included if they had documented ETCO2 and arterial PaCO2 measurements. Arterial PaCO2 data that could not be linked to within 5 minutes of ETCO2 were excluded. Bland-Altman plots were calculated to describe agreement. A total of 73 patients were identified. Aetiology was arranged into three categories: 13 (17.8%) medical, 22 (30.1%) traumatic and 38 (52.1%) out-of-hospital cardiac arrest (OHCA). The median PaCO2-ETCO2 gradient was 2.0 [1.3-3.1] kPa. A PaCO2-ETCO2 gradient of 0-1 kPa was seen for only 11 (15.1%) of total patients. The Bland-Altman agreement for all aetiologies was more than the accepted gradient of 0-1 kPa with the largest bias and widest limits of agreement seen for OHCA (-3.2 [0.3 - -6.8]). The magnitude of the differences between the ETCO2 and PaCO2, levels of variation and inability to predict this suggest that ETCO2 is not a suitable surrogate upon which to base ventilatory settings in conditions where pH or PaCO2 require precise control.

Comparison of different end-tidal carbon dioxide levels in preventing postoperative nausea and vomiting in gynaecological patients undergoing laparoscopic surgery

The aim of this study was to compare different end-tidal carbon dioxide (EtCO2) levels to prevent postoperative nausea and vomiting (PONV) caused by increased intracranial pressure due to pneumoperitoneum and Trendelenburg position in gynaecological laparoscopic surgery. A total of 60 female patients aged 25–50 years who would undergo laparoscopic gynaecological surgery under general anaesthesia were randomised into two groups: group A (EtCO2: 26 − 35 mmHg, n = 30) and group B (EtCO2: 36 − 45 mmHg, n = 30). In both groups, ONSD and EtCO2 of the patients were measured at baseline after anaesthesia induction (T b), at 5 min after pneumoperitoneum (T PP5), and at 10 min intervals after Trendelenburg position (T PP10, T PP20, T PP30). At 5 (T D5) and 10 min (T D10) after deflation, ONSD measurements were repeated. The incidence and severity of PONV of the patients, and antiemetic drugs used in both groups were assessed in the postoperative period. In the intraoperative follow-up periods, T PP5 and subsequent EtCO2 values, as well as T PP10 and subsequent ONSD values, were significantly higher in group B and the incidence of nausea, the PONV scores and the incidence of rescue antiemetic use significantly lower in group A than in group B (p<.001 for all). This result indicates that low EtCO2 levels have beneficial effects on ICP and PONV in laparoscopic gynaecological operations. Impact statement What is already known on this subject? Laparoscopic gynaecologic surgery has been a more preferred technique. The incidence of postoperative nausea and vomiting (PONV) after laparoscopic gynaecologic surgery is remarkably high. In the prevention of PONV after gynaecologic laparoscopic surgery, single and multiple drug therapies and methods have been used. What the results of this study add? Postoperative nausea and vomiting caused by intracranial pressure (ICP) increase due to carbon dioxide pneumoperitoneum and Trendelenburg position in gynaecologic laparoscopic surgeries were decreased in the early postoperative period by low end-tidal carbon dioxide levels in the intraoperative period. It was shown that low end-tidal carbon dioxide levels have beneficial effects on ICP and PONV in laparoscopic gynaecologic operations. What the implications are of these findings for clinical practice and/or further research? This result indicates that low end-tidal carbon dioxide levels have beneficial effects on ICP and PONV in laparoscopic gynaecologic operations.

Return to training in the COVID‐19 era: The physiological effects of face masks during exercise

COVID‐19 outbreak has a profound impact on almost every aspect of life. Universal masking is recommended as a means of source control. Routinely exercising in a safe environment is an important strategy for healthy living during this crisis. As sports clubs and public spaces may serve a source of viral transmission, masking may become an integral part of physical activity. This study aimed to assess the physiological effects of wearing surgical masks and N95 respirators during short‐term strenuous workout. This was a multiple cross‐over trial of healthy volunteers. Using a standard cycle ergometry ramp protocol, each subject performed a maximal exercise test without a mask, with a surgical mask, and with an N95 respirator. Physiological parameters and time to exhaustion were compared. Each subject served his own control. Sixteen male volunteers (mean age and BMI of 34 ± 4 years and 28.72 ± 3.78 kg/m2, respectively) completed the protocol. Heart rate, respiratory rate, blood pressure, oxygen saturation, and time to exhaustion did not differ significantly. Exercising with N95 mask was associated with a significant increase in end‐tidal carbon dioxide (EtCO2) levels. The differences were more prominent as the load increased, reaching 8 mm Hg at exhaustion (none vs N95, P = .001). In conclusion, in healthy subjects, short‐term moderate‐strenuous aerobic physical activity with a mask is feasible, safe, and associated with only minor changes in physiological parameters, particularly a mild increase in EtCO2. Subjects suffering from lung diseases should have a cautious evaluation before attempting physical activity with any mask.

Effects of Sedation and/or Sedation/Analgesic Drugs Administered during Central Venous Catheterization on the Level of End-tidal Carbon Dioxide Measured by Nasal Cannula in Our PICU.

Aims and objectivesSedatives and analgesics are commonly used in pediatric intensive care units during minor invasive procedures. Here, we aimed to measure the changes in end-tidal carbon dioxide (EtCO2) levels with different sedation/analgesic drug administrations (midazolam, ketamine, midazolam + ketamine/fentanyl) during central venous catheterization.Materials and methodsThis prospective study included 44 patients who needed sedation/analgesia for central venous catheterization. Patients were sedated with midazolam, ketamine, or midazolam + fentanyl/ketamine. End-tidal carbon dioxide values were measured before and after sedation–analgesia with nasal cannula and recorded from the capnograph. Oxygen saturation (SO2) was monitored by pulse oximetry. Whether respiratory depression occurred during the process was recorded.ResultsDuring the procedure, 15 (34%) patients were given 0.1 mg/kg dose of midazolam described as group I, 18 (41%) patients were given 1 mg/kg dose of ketamine only described as group II, and 11 (25%) patients who could not be effective sedated with a single sedative–analgesic agent were given either 1 mg/kg dose of ketamine or 2 μg/kg dose of fentanyl together with 0.1 mg/kg dose of midazolam described as group III. According to our findings, hypoxia (54.5%) and hypercarbia (45.5%) were detected higher in group III but it was not statistically significant (p = 0.255, p = 0.364). Hypercarbia was detected in 29.5% patients, in 62% of these patients hypercarbia was accompanied by hypoxia, and 38% had only hypercarbia. When presedation and postsedation EtCO2 values were compared, we detected a statistically significant difference in all groups.ConclusionWe detected hypercarbia unaccompanied by hypoxemia in 38% patients. And we think that we have identified these patients early due to measurement of EtCO2 by nasal cannula. This study demonstrated that EtCO2 monitoring via nasal cannula is a feasible and practical way to follow ventilation during sedation/analgesia.How to cite this articleAslan N, Yildizdas D, Horoz OO, Arslan D, Coban Y, Sertdemir Y. Effects of Sedation and/or Sedation/Analgesic Drugs Administered during Central Venous Catheterization on the Level of End-tidal Carbon Dioxide Measured by Nasal Cannula in Our PICU. Indian J Crit Care Med 2020;24(8):705–708.

Carbon dioxide elimination pattern in assessing the risk of an unfavorable outcome in cardiac surgery

Aim. To assess the influence of resting partial pressure of end-tidal carbon dioxide (PetCO2) levels on the long-term results of cardiac surgery.Materials and methods. This prospective cohort study included 454 patients with coronary artery disease who underwent elective coronary artery bypass graft surgery. Before surgery, all patients underwent pulmonary function tests, including body plethysmography, lung diffusion capacity assessment and cardiopulmonary exercise testing with the determination of ventilatory and gas exchange parameters, including PetCO2 at rest. The endpoint was the 2-year survival rate after surgery.Results. Parameters characterizing the obstructive breathing pattern, the lung diffusion capacity, and resting PetCO2 levels had a significant predictor value in relation to long-term survival after cardiac surgery. Among the baseline clinical and functional characteristics, a significant influence on long-term results was shown by the EuroSCORE II (OR 1,69 (1,26-2,27), p=0,001). The highest sensitivity and specificity in relation to long-term mortality risk after coronary artery bypass grafting was shown by resting PetCO2 value equal to 31 mm Hg (area under the ROC curve 0,74 (0,64-0,86), p&lt;0,001).Conclusion. The resting PetCO2 level below 31 mm Hg in patients with coronary artery disease showed a significant effect on the increased long-term mortality risk after cardiac surgery, which is important for patients with exercise intolerance.

The impact of ventilation rate on end-tidal carbon dioxide level during manual cardiopulmonary resuscitation

AimVentilation rate is a confounding factor for interpretation of end-tidal carbon dioxide (ETCO2) during cardiopulmonary resuscitation (CPR). The aim of our study was to model the effect of ventilation rate on ETCO2 during manual CPR in adult out-of-hospital cardiac arrest (OHCA). MethodsWe conducted a retrospective analysis of OHCA monitor-defibrillator files with concurrent capnogram, compression depth, transthoracic impedance and ECG. We annotated pairs of capnogram segments presenting differences in average ventilation rate and average ETCO2 value but with other influencing factors (e.g. compression rate and depth) presenting similar values within the pair. ETCO2 variation as a function of ventilation rate was adjusted through curve fitting using non-linear least squares as a measure of goodness of fit. ResultsA total of 141 pairs of segments from 102 patients were annotated. Each pair provided a single data point for curve fitting. The best goodness of fit yielded a coefficient of determination R2 of 0.93. Our model described that ETCO2 decays exponentially with increasing ventilation rate. The model showed no differences attributable to the airway type (endotracheal tube or supraglottic King-LT-D). ConclusionCapnogram interpretation during CPR is challenging since many factors influence ETCO2. For adequate interpretation, we need to know the effect of each factor on ETCO2. Our model allows quantifying the effect of ventilation rate on ETCO2 variation. Our findings could contribute to better interpretation of ETCO2 during CPR.

Excluding Pulmonary Embolism with End-tidal Carbon Dioxide: Accuracy, Cost, and Harm Avoidance.

A non-randomized single center prospective, descriptive, correlational design was used to determine what end-tidal carbon dioxide (EtCO2) level provided the best sensitivity, specificity, and negative predictive value to exclude pulmonary embolism (PE) diagnosis in hemodynamically stable hospitalized adults (n = 111). The financial impact and harm avoidance of adding EtCO2 to the PE diagnostic process also were examined. PE diagnosis was determined by computed tomography pulmonary angiography (CTPA). PE prevalence was 18.9%. Mean±SD EtCO2 was lower for PE positive than negative participants (28 ± 7.8 to 33 ± 8.1 mmHg respectively 95% CI: 1.22-8.96; P = .01). For PE exclusion, an EtCO2 cutoff ≥42 mmHg yielded 100% sensitivity, 12.2% specificity, and 100% negative predictive value. For every six inpatients assessed with EtCO2, one could be saved from unnecessary CTPA. Eliminating unnecessary CTPA removes the potential harm associated with radiation and intravenous contrast exposure. Additionally, an EtCO2 cutoff ≥42 mmHg could eliminate ~$88,000/year in healthcare waste at this institution.

Applicability of Capnography in the Adult ICU During Physical Therapy: A Systematic Review

PurposeThe purpose of this review was three‐fold: first, evaluate the strength and quality of the current research evidence on usage of capnography, second, determine whether current evidence regarding the use capnography during physical therapy should be considered when making decisions regarding patient’s response to physical therapy; and third, identify weaknesses in the current evidence and area for continued research.Background/SignificanceCapnography is typically used in emergency departments and postoperatively but is not commonly used during physical therapy. Pulse oximetry is typically used to monitor oxygen desaturation and hypoxemia during physical therapy but does not predict or monitor respiratory depression. Capnography monitoring during exercise and mobility could have benefits for physical therapists monitoring patients during therapy as well as provide prognostic value of patient progress.Methods and MaterialsA literature search was completed using: Science Direct, IOP Science, PLOS one, Google scholar, Wiley, EBSCO Host, CINAHL Complete, Cochrane Library, and PubMed. Keywords: capnometry, capnography accuracy, physical therapy, application of capnography, mobility, monitoring. Articles selected for review were those of original research or systematic review published since 2009 and evaluated for quality using the Oxford Centre for Evidence‐Based Medicine 2011 levels of evidence system.ResultsTwenty‐seven articles are included for this study. Six articles were included in the introduction. Seven articles examined the current practices for use of capnography; six studies looked at the use of capnography in the intensive care unit. Three articles on pulse oximetry and capnography with mobility, two articles on the use of monitoring ventilation and oximetry during exercise, and three studies on biologically‐based assessment tools for physical therapy.ConclusionsEvidence suggests that monitoring partial pressure end‐tidal carbon dioxide (PETCO2) levels in patients during rest and exercise may provide more prognostic value of possible adverse events in patients with conditions such as heart failure. Monitoring ventilatory responses in patients is valuable in physical therapy as it indicates tolerance to activity. Evidence suggests there is a significant correlation between PETCO2 and cardiac output. Recent research also suggests regardless of mask or cannula used on patients, diagnostic accuracy of measuring PETCO2 is similar during normal and hyper‐ventilatory states. With increasing application of capnography in intensive care settings, studies involving usage in physical therapy are warranted.

Duty cycle of 33% increases cardiac output during cardiopulmonary resuscitation.

The aim of this study was to investigate whether 33% duty cycle increases end-tidal carbon dioxide (ETCO2) level, a surrogate measurement for cardiac output during cardiopulmonary resuscitation (CPR), compared with 50% duty cycle. Six pigs were randomly assigned to the DC33 or DC50 group. After 3 min of induced ventricular fibrillation (VF), CPR was performed for 5 min with 33% duty cycle (DC33 group) or with 50% duty cycle (DC50 group) (phase I). Defibrillation was delivered until return of spontaneous circulation (ROSC) thereafter. After 30 min of stabilization, the animals were re-assigned to the opposite groups. VF was induced again, and CPR was performed (phase II). The primary outcome was ETCO2 during CPR, and the secondary outcomes were coronary perfusion pressure (CPP), systolic arterial pressure (SAP), diastolic arterial pressure (DAP), and right atrial pressure (RAP). Mean ETCO2 was higher in the DC33 group compared with the DC50 group (22.5 mmHg vs 21.5 mmHg, P = 0.018). In a linear mixed model, 33% duty cycle increased ETCO2 by 1.0 mmHg compared with 50% duty cycle (P < 0.001). ETCO2 increased over time in the DC33 group [0.6 mmHg/min] while ETCO2 decreased in the DC50 group [-0.6 mmHg/min] (P < 0.001). Duty cycle of 33% increased SAP (6.0 mmHg, P < 0.001), DAP (8.9 mmHg, P < 0.001) RAP (2.6 mmHg, P < 0.001) and CPP (4.7 mmHg, P < 0.001) compared with the duty cycle of 50%. Duty cycle of 33% increased ETCO2, a surrogate measurement for cardiac output during CPR, compared with duty cycle of 50%. Moreover, ETCO2 increased over time during CPR with 33% duty cycle while ETCO2 decreased with 50% duty cycle.

Evaluation of the effect of Boyle-Davis mouth gag on intracranial pressure in patients undergoing adenotonsillectomy by using ultrasonographic optic nerve sheath diameter measurement

ObjectiveWe aimed to evaluate the effect of an increase in intracranial pressure (ICP) due to sympatho-adrenergic response caused by mouth gag and tongue depressor during adenotonsillectomy by measuring the optic nerve sheath diameter (ONSD) by ultrasonographic method. MethodsForty patients (age range 3–12 years) who underwent adenotonsillectomy were included in the study. All patients underwent surgery under general anesthesia with endotracheal intubation. Boyle-Davis mouth gag was used during the procedure. ONSD measurement was performed and a high-frequency linear probe. All ONSD measurements were performed by a single investigator experienced in the use of ultrasound. Ultrasonographically measured ONSD before induction was accepted as baseline (T0) value. Immediately after insertion of the mouth gag (T1), just before removal of the mouth gag (T2), and just before extubation (T3), ultrasonographic measurements of ONSD were recorded. ResultsWhen patients' baseline ONSD values were compared with the values obtained in T1, T2, T3, and a statistically significant increase was detected. The ONSD value measured before removing the mouth gag (T2) was significantly higher than the ONSD value measured immediately after the insertion of the mouth gag (T1). The ONSD value measured just before extubation (T3) and after removal of the mouth gag was significantly lower than the ONSD value (T2) measured just before removal of the mouth gag. When heart rate, mean arterial pressure (MAP), peripheral oxygen saturation (SpO2) values of T0, T1, T2, T3 were compared, any statistically significant difference was not observed. When end-tidal carbon dioxide level (etCO2) and peak inspiratory pressure (PIP) values of T1, T2, T3 were compared, any statistically significant difference was not observed. ConclusionThis study showed that the Boyle-Davis mouth gag used during the adenotonsillectomy operation resulted in a significant increase in the diameter of the optic nerve sheath measured ultrasonographically and increased the ONSD even further during the time the mouth gag was remained in situ. In children with intracranial pathologies who will undergo adenotonsillectomy or those with increased ICP-related risk factors, the risks that may arise from the effect of the Boyle-Davis mouth gag on ICP should be considered.

End-tidal carbon dioxide levels during resuscitation and carbon dioxide levels in the immediate neonatal period and intraventricular haemorrhage

Abnormal levels of end-tidal carbon dioxide (EtCO2) during resuscitation in the delivery suite are associated with intraventricular haemorrhage (IVH) development. Our aim was to determine whether carbon dioxide (CO2) levels in the first 3 days after birth reflected abnormal EtCO2 levels in the delivery suite, and hence, a prolonged rather than an early insult resulted in IVH. In addition, we determined if greater EtCO2level fluctuations during resuscitation occurred in infants who developed IVH. EtCO2 levels during delivery suite resuscitation and CO2 levels on the neonatal unit were evaluated in 58 infants (median gestational age 27.3 weeks). Delta EtCO2 was the difference between the highest and lowest level of EtCO2. Thirteen infants developed a grade 3–4 IVH (severe group). There were no significant differences in CO2 levels between those who did and did not develop an IVH (or severe IVH) on the NICU. The delta EtCO2 during resuscitation differed between infants with any IVH (6.2 (5.4–7.5) kPa) or no IVH (3.8 (2.7–4.3) kPA) (p < 0.001) after adjusting for differences in gestational age. Delta EtCO2 levels gave an area under the ROC curve of 0.940 for prediction of IVH.Conclusion: The results emphasize the importance of monitoring EtCO2 levels in the delivery suite.What is Known:• Abnormal levels of carbon dioxide (CO2) in the first few days after birth and abnormal end-tidal CO2levels (EtCO2) levels during resuscitation are associated in preterm infants with the risk of developing intraventricular haemorrhage (IVH).What is New:• There were no significant differences in NICU CO2levels between those who developed an IVH or no IVH.• There was a poor correlation between delivery suite ETCO2levels and NICU CO2levels.• Large fluctuations in EtCO2during resuscitation in the delivery suite were highly predictive of IVH development in preterm infants.

Abstract 436: Ventilation Rate Impact on End-Tidal Carbon Dioxide Levels During Manual Cardiopulmonary Resuscitation

Introduction: End-tidal carbon dioxide (ETCO2) levels during cardiopulmonary resuscitation (CPR) depend primarily on the blood flow generated by chest compressions, on the ventilation rate and on the metabolic activity of the patient tissues. A better characterization of the influence of each factor is warranted. Objective: To assess the quantitative relation between ETCO2 and ventilation rate from retrospective analysis of adult out-of-hospital resuscitations. Methods: Monitor recordings of 163 adult out-of-hospital cardiac arrest cases treated by Tualatin Valley Fire &amp; Rescue (Tigard, OR) from 2012 through 2017. Recordings contained concurrent capnogram, ECG, transthoracic impedance (TI) and compression depth. Episodes were manually inspected to identify pairs of segments with different ventilation rates ( vr 1, vr 2) and meeting the following criteria: 1) Reliable capnogram to annotate the ETCO2 value of each segment ( ET 1, ET 2). 2) A maximum of 2 min separation between segments so that similar metabolic activity could be assumed. 3) Absence of circulation, by inspecting the ECG and the TI signal. 4) Compression depth and rate variation between segments &lt; 4 mm and 8 compressions per minute, respectively. We applied curve fitting to the data with a custom equation (see figure) and non-linear least squares as fit option. Results: Forty pairs of segments were included. The figure shows the measurements and the resulting fitting curve normalized to vr 1 = 10 ventilations per minute (vpm). Factor K was 0.93, and the coefficient of determination R 2 was 0.90. Thus, for instance, the ETCO2 at 5 vpm would be 1.64 times the ETCO2 at 10 vpm. Similarly, the ETCO2 at 15 vpm would be 0.80 times the ETCO2 at 10 vpm. Conclusions: The obtained curve may help to eliminate the influence of ventilation rate on ETCO2 during cardiopulmonary resuscitation. This finding is a step forward to a better understanding of ETCO2 variation during the course of resuscitation.