End-tidal Carbon Dioxide Tension Difference Research Articles

Arterial to end-tidal carbon dioxide tension difference (CO2 gap) as a prognostic marker for adverse outcomes in emergency department patients presenting with suspected sepsis.

The arterial to end-tidal carbon dioxide tension difference (CO2 gap) correlates with physiologic dead space. The prognostic value of increased CO2 gap in trauma and respiratory distress patients is documented. Transpulmonary arteriovenous shunting is identified as a predictor of mortality in non-pulmonary sepsis. We set out to investigate the prognostic value of the CO2 gap in a pilot study of patients with suspected sepsis from non-respiratory causes. Patients presenting to tertiary Australian ED with suspected sepsis (n = 215) underwent near-simultaneous end-tidal carbon dioxide and partial pressure of carbon dioxide measurements. We investigated the correlation of CO2 gap levels with the primary outcome of in-hospital mortality (IHM) and secondary outcomes of sepsis (ΔSOFA ≥2) and IHM and/or intensive care unit stay ≥72 h (IHM/ICU72h) in patients with sepsis because of non-respiratory causes. Among patients included in the analysis (n = 165), the CO2 gap showed modest positive correlation with qSOFA (ρ = 0.39) and weak positive correlation with SOFA scores (ρ = 0.29) (both P < 0.01). The CO2 gap had modest predictive value for primary outcome (IHM), area under receiver operating curve (AUROC 0.85, 95% confidence interval [CI] 0.78-0.90) and IHM/ICU72h outcome (AUROC 0.80, 95% CI 0.73-0.86), but lower predictive value for sepsis outcome (AUROC 0.64, 95% CI 0.55-0.71) (all P < 0.001). We report modest test performance for primary outcome at CO2 gap ≥5 and ≥10 mmHg cut-offs. In this pilot study of patients with suspected sepsis from non-respiratory causes, an increased CO2 gap demonstrates value in risk stratification and needs to be further evaluated and compared to other existent biomarkers.

The effect of a peptide-containing synthetic lung surfactant on gas exchange and lung mechanics in a rabbit model of surfactant depletion

BackgroundCurrently, a new generation of synthetic pulmonary surfactants is being developed that may eventually replace animal-derived surfactants used in the treatment of respiratory distress syndrome. Enlightened by this, we prepared a synthetic peptide-containing surfactant (Synsurf) consisting of phospholipids and poly-l-lysine electrostatically bonded to poly-l-glutamic acid. Our objective in this study was to investigate if bronchoalveolar lavage (BAL)-induced acute lung injury and surfactant deficiency with accompanying hypoxemia and increased alveolar and physiological dead space is restored to its prelavage condition by surfactant replacement with Synsurf, a generic prepared Exosurf, and a generic Exosurf containing Ca2+.MethodsTwelve adult New Zealand white rabbits receiving conventional mechanical ventilation underwent repeated BAL to create acute lung injury and surfactant-deficient lung disease. Synthetic surfactants were then administered and their effects assessed at specified time points over 5 hours. The variables assessed before and after lavage and surfactant treatment included alveolar and physiological dead space, dead space/tidal volume ratio, arterial end-tidal carbon dioxide tension (PCO2) difference (mainstream capnography), arterial blood gas analysis, calculated shunt, and oxygen ratios.ResultsBAL led to acute lung injury characterized by an increasing arterial PCO2 and a simultaneous increase of alveolar and physiological dead space/tidal volume ratio with no intergroup differences. Arterial end-tidal PCO2 and dead space/tidal volume ratio correlated in the Synsurf, generic Exosurf and generic Exosurf containing Ca2+ groups. A significant and sustained improvement in systemic oxygenation occurred from time point 180 minutes onward in animals treated with Synsurf compared to the other two groups (P < 0.001). A statistically significant decrease in pulmonary shunt (P < 0.001) was found for the Synsurf-treated group of animals, as well as radiographic improvement in three out of four animals in that group.ConclusionIn general, surfactant-replacement therapy in the animals did not fully restore the lung to its prelavage condition. However, our data show that the formulated surfactant Synsurf improves oxygenation by lowering pulmonary shunt.

Clinical significance of arterial and end-tidal carbon dioxide tension difference (a-ETDCO2) in pulmonary gas exchange

Clinical significance of arterial and end-tidal carbon dioxide tension difference (a-ETDCO2) in pulmonary gas exchange

Factors Influencing Development of Subcutaneous Carbon Dioxide Emphysema in Laparoscopic Totally Extraperitoneal Inguinal Hernia Repair

There is a paucity of published data on the incidence of subcutaneous emphysema and the causative factors responsible for its occurrence during laparoscopic procedures. This study was undertaken to evaluate the incidence and factors associated with the occurrence of subcutaneous emphysema in patients undergoing a laparoscopic totally extraperitoneal (TEP) inguinal hernia repair. The prospective study included 100 patients who presented with a primary inguinal hernia and underwent an elective laparoscopic TEP hernia repair from November 2003 to May 2005. Various factors, including age, body mass index (BMI), type of hernia (i.e., unilateral or bilateral, indirect or direct), duration of surgery, and end-tidal carbon-dioxide tension (start and peak), were evaluated. A grading system was evolved to document clinically apparent subcutaneous emphysema immediately and at 6 and 24 hours after the surgical procedure. A BMI <25, longer operating time (especially >1 hour), and higher end-tidal carbon-dioxide tension (start, peak, and difference) were found to be significantly associated with the development of subcutaneous emphysema. Age and type of hernia -- unilateral versus bilateral, direct versus indirect -- were not found to be statistically significant factors. The incidence of subcutaneous emphysema in laparoscopic extraperitoneal hernia repairs is high and largely under-reported. Once it is noted, the progression of the surgical emphysema during this type of surgery can have serious complications (e.g., cardiovascular and hemodynamic disturbances) unless timely, appropriate measures are taken. Etiology of subcutaneous emphysema is multifactorial, with no single factor having a prominent association.

The value of end-tidal carbon dioxide monitoring during systemic-to-pulmonary artery shunt insertion in cyanotic children

Objective To investigate the relationship between end-tidal carbon dioxide levels and augmentation of pulmonary blood flow achieved by insertion of systemic-pulmonary shunts. Design Prospective clinical study. Settings University hospital. Participants Nineteen cyanotic children with tetralogy of Fallot. Interventions Modified Blalock-Taussig shunt operations were performed on the left side in 14 patients and on the right side in 5 patients. Measurements and Main Results End-tidal carbon dioxide tension was recorded, and an arterial blood gas sample was obtained simultaneously after thoracotomy (T0) and after completion of systemic-pulmonary shunt (T1). End-tidal carbon dioxide tension was significantly higher ( p < 0.01), and arterial to end-tidal carbon dioxide tension difference was significantly lower ( p < 0.01) at T1 when compared with T0. The increase in end-tidal carbon dioxide showed a statistically significant correlation with the response of arterial oxygen saturation ( r = 0.61, p < 0.01). The fall in arterial to end-tidal carbon dioxide tension difference correlated inversely with the change of oxygen saturation ( r = −0.81, p < 0.0001). Conclusion It is concluded that end-tidal carbon dioxide tension alterations offer an alternative intraoperative tool to monitor pulmonary blood flow during modified Blalock-Taussig shunt procedures.

Arterial to End-Tidal Carbon Dioxide Tension Difference in Children with Congenital Heart Disease

Arterial to End-Tidal Carbon Dioxide Tension Difference in Children with Congenital Heart Disease

Arterial to end-tidal carbon dioxide tension difference in children with congenital heart disease

In children with congenital cyanotic heart disease, right-to-left intracardiac shunting causes an obligatory difference between arterial and end-tidal carbon dioxide tension (PaCO2-PE'CO2) as venous blood, rich in carbon dioxide, is added to the arterial circulation. This obligatory PaCO2-PE'CO2 difference, which can be predicted from knowledge of oxygen saturation, haemoglobin concentration and PaCO2, increases as oxygen saturation decreases, most markedly when the haemoglobin concentration is high. A second possible cause of the PaCO2-PE'CO2 difference is the effect of pulmonary hypoperfusion caused by the shunt. We studied 60 children undergoing cardiac surgery and compared the predicted the PaCO2-PE'CO2 difference with measured values to investigate the extent to which additional factors influence the clinically observed PaCO2-PE'CO2. In many children, observed values were much greater than predicted, which is compatible with some degree of pulmonary hypoperfusion. However, this was not felt to represent the complete picture in all patients. Another cause of ventilation-perfusion mismatch was suspected in those children who showed a considerable improvement in oxygen saturation during ventilation with an increased FIO2. We believe that pulmonary congestion caused by large left-to-right shunts may further increase the PaCO2-PE'CO2 difference.

Accuracy of end-tidal carbon dioxide monitoring using the NBP-75 microstream capnometer. A study in intubated ventilated and spontaneously breathing nonintubated patients.

Arterial carbon dioxide partial pressure measurements using the NBP-75 microstream capnometer were compared with direct PaCO2 values in patients who were (a) not intubated and spontaneously breathing, and (b) patients receiving intermittent positive pressure ventilation of the lungs and endotracheal anaesthesia. Twenty ASA physical status I-III patients, undergoing general anaesthesia for orthopaedic or vascular surgery were included in a prospective crossover study. After a 20-min equilibration period following the induction of general anaesthesia, arterial blood was drawn from an indwelling radial catheter, while the end-tidal carbon dioxide partial pressure was measured at the angle between the tracheal tube and the ventilation circuit using a microstream capnometer (NBP-75, Nellcor Puritan Bennett, Plesanton, CA, USA) with an aspiration flow rate of 30 mL min(-1). Patients were extubated at the end of surgery and transferred to the postanaesthesia care unit, where end-tidal carbon dioxide was sampled through a nasal cannula (Nasal FilterLine, Nellcor, Plesanton, CA, USA) and measured using the same microstream capnometer. In each patient six measurements were performed, three during mechanical ventilation and three during spontaneous breathing. A good correlation between arterial and end-tidal carbon dioxide partial pressure was observed both during mechanical ventilation (r = 0.59; P = 0.0005) and spontaneous breathing (r = 0.41; P = 0.001); while no differences in the arterial to end-tidal carbon dioxide tension difference were observed when patients were intubated and mechanically ventilated (7. 3 +/- 4 mmHg; CI95: 6.3-8.4) compared to values measured during spontaneous breathing in the postanesthesia care unit, after patients had been awakened and extubated (6.5 +/- 4.8 mmHg; CI95: 5. 2-7.8) (P = 0.311). The mean difference between the arterial to end-tidal carbon dioxide tension gradient measured in intubated and non-intubated spontaneously breathing patients was 1 +/- 6 mmHg (CI95: -11-+13). We conclude that measuring the end-tidal carbon dioxide partial pressure through a nasal cannula using the NBP-75 microstream capnometer provides an estimation of arterial carbon dioxide partial pressure similar to that provided when the same patients are intubated and mechanically ventilated.

Ketamine infusion versus isoflurane for the maintenance of anesthesia in the prebypass period in children with tetralogy of fallot

Objective: To evaluate the use of ketamine in comparison with isoflurane in the maintenance of anesthesia in children with tetralogy of Fallot. Design: Prospective, randomized study. Setting: University hospital. Participants: Fifty children scheduled for correction of tetralogy of Fallot. Interventions: After intubation, patients were assigned randomly to receive 2 different anesthesia maintenance regimens: group I, isoflurane, 0 to 1% plus fentanyl, 0.1 μg/kg/min; group II, ketamine, 0 to 5 mg/kg/h, plus fentanyl, 0.1 μg/kg/min. Isoflurane concentration and ketamine infusion rate were adjusted to maintain arterial pressure within 25% of baseline. Hemodynamic and respiratory parameters were recorded at the end of 4 intervals: T0, before induction of anesthesia; T1, induction to 10 minutes postintubation; T2, 10 minutes postintubation to poststernotomy; and T3, poststernotomy to completion of catheterizations. Measurements and Main Results: In comparing group I with group II, significant differences were observed in mean arterial pressure (p < 0.0001), heart rate (p < 0.01), arterial oxygen saturation (p < 0.0001), arterial oxygen tension (p < 0.001), arterial carbon dioxide tension (p < 0.001), arterial pH (p < 0.0001), base excess (p < 0.05), and arterial to end-tidal carbon dioxide tension difference (p < 0.01) at T3. Conclusion: The use of ketamine anesthesia is recommended as an alternative maintenance regimen in children undergoing definitive correction of tetralogy of Fallot. Copyright © 2000 by W.B. Saunders Company

Arterial to end-tidal carbon dioxide tension difference in anaesthetized adults mechanically ventilated via a laryngeal mask or a cuffed oropharyngeal airway

To evaluate arterial (PaCO2), end-tidal (PETCO2) and carbon dioxide tension difference during mechanical ventilation with extratracheal airways, 60 patients ASA physical status I-II, receiving general anaesthesia for minor extra-abdominal procedures were randomly allocated to receive either a cuffed oropharyngeal airway (group COPA, n=30) or a laryngeal mask (group LMA, n=30). The lungs were mechanically ventilated by IPPV using a 60% nitrous oxide and 1-1.5% isoflurane in oxygen mixture (VT=8 mL kg−1; RR = 12 b min−1; I/E = 1/2). After PETCO2 had been stable for at least 10 min after airway placement, haemodynamic variables and PETCO2 were recorded and an arterial blood sample was obtained for measurement of PaCO2. No differences in anthropometric parameters, smoking habit, haemodynamic variables and incidence of untoward events were observed between the two groups. Airway manipulation, to maintain adequate ventilation, was required in only nine patients in the cuffed oropharyngeal airway group (30%)(P < 0.0005); however, in no case was it necessary to remove the designated extratracheal airway due to unsuccessful mechanical ventilation. The mean difference between arterial and end-tidal carbon dioxide partial pressure was 0.4±0.3 KPa in the laryngeal mask group (95% confidence intervals: 0.3-0.5 KPa) and 0.3±0.26 KPa in the cuffed oropharyngeal airway group (95% confidence intervals: 0.24-0.4 KPa) (P = NS). We conclude that in healthy adults who are mechanically ventilated via the cuffed oropharyngeal airway, the end-tidal carbon dioxide determination is as accurate an indicator of PaCO2 as that measured via the laryngeal mask, allowing capnometry to be reliably used to evaluate the adequacy of ventilation.

Ventilatory response and arterial blood gases during exercise in children.

To investigate the difference in ventilatory response to exercise between children and young adults, we administered a treadmill progressive exercise test to seven boys (aged 8 to 11 y [group A]) and six male young adults (aged 14 to 21 y [group B]), who had a history of Kawasaki disease without significant coronary arterial lesions, and analyzed their arterial blood gases. There was no significant difference in arterial PO2 or the end-tidal to arterial oxygen tension difference during exercise between groups A and B. The arterial PCO2 (PaCO2) at the ventilatory anaerobic threshold and at peak exercise was significantly lower in group A than in group B (p < 0.05). The arterial to end-tidal carbon dioxide tension difference at peak exercise was significantly greater in group B than in group A (p < 0.05), whereas there was no significant difference at rest or at the ventilatory anaerobic threshold level. The arterial to end-tidal carbon dioxide tension difference at peak exercise was correlated with tidal volume (p < 0.01) and carbon dioxide production (p < 0.05) at peak exercise in all subjects. Although improvement in the physiologic dead space/tidal volume ratio during exercise was smaller in group A than in group B, there was no significant difference in total alveolar ventilation during exercise. However, the total carbon dioxide production during exercise was significantly smaller in group A than in group B. These data suggest that PaCO2 during exercise is better estimated by end-tidal carbon dioxide tension in children than in young adults, that there is a significant difference in change of the PaCO2 during exercise between children and young adults, and that the decrease in PaCO2 in children is related to the mismatch between well-maintained alveolar ventilation and immature metabolic development in the working muscles during moderate-to-severe exercise.

The Effect of Lung Disease in the Arterial to End-Tidal Carbon Dioxide Tension Difference

The Effect of Lung Disease in the Arterial to End-Tidal Carbon Dioxide Tension Difference

Physiological dead space/tidal volume ratio during face mask, laryngeal mask, and cuffed oropharyngeal airway spontaneous ventilation

Objective: To compare the physiological dead space/tidal volume ratio and arterial to end-tidal carbon dioxide tension (ETCO 2) difference during spontaneous ventilation through a face mask, a laryngeal mask (LMA), or a cuffed oropharyngeal airway. Design: Prospective, randomized, cross-over study. Setting: Inpatient anesthesia at a university department of orthopedic surgery. Patients: 20 ASA physical status I and II patients, without respiratory disease, who underwent ankle and foot surgery. Interventions: After a peripheral nerve block was performed, propofol anesthesia was induced and then maintained with a continuous intravenous (IV) infusion (4 to 6 mg/kg/h). A face mask, a cuffed oropharyngeal airway, or an LMA were placed in each patient in a random sequence. After 15 minutes of spontaneous breathing through each of the airways, ventilatory variables, as well as arterial, end-tidal, and mixed expired CO 2 partial pressure, were measured, and physiological dead space/tidal volume ratio was calculated. Measurements and Main Results: Expired minute volume and respiratory rate (RR) were lower with LMA (5.6 ± 1.2 L/min and 18 ± 3 breaths/min) and the cuffed oropharyngeal airway (5.7 ± 1 L/minand 18 ± 3 breaths/min) than the face mask (7.1 ± 0.9 L/min and 21 ± 3 breaths/min) (p = 0.0002 and p = 0.013, respectively). Physiological dead space/tidal volume ratio and arterial to end tidal CO 2 tension difference were similar with the cuffed oropharyngeal airway (3 ± 0.4 mmHg and 4.4 ± 1.4 mmHg) and LMA (3 ± 0.6 mmHg and 3.7 ± 1 mmHg) and lower than with the face mask (4 ± 0.5 mmHg and 6.7 ± 2 mmHg) (p = 0.0001 and p = 0.001, respectively). Conclusion: Because of the increased dead space/tidal volume ratio, breathing through a face mask required higher RR and expired minute volume than either the cuffed oropharyngeal airway or LMA, which, in contrast, showed similar effects on the quality of ventilation in spontaneously breathing anesthetized patients.

A.151 Arterial to end-tidal carbon dioxide tension difference in healthy subjects during spontaneous or controlled ventilation under inhalation anaesthesia

A.151 Arterial to end-tidal carbon dioxide tension difference in healthy subjects during spontaneous or controlled ventilation under inhalation anaesthesia

The quality of breathing and capnography during laryngeal mask and facemask ventilation

Clinical measures of ventilation and the relationship between arterial and end-tidal carbon dioxide tensions were studied during inhalational anaesthesia in 18 patients using a laryngeal mask airway or a facemask. Tidal volumes were similar in both groups but expired minute volume, respiratory rate and physiological deadspace ventilation were significantly increased in the facemask group. Both end-tidal and arterial carbon dioxide tensions were higher in the laryngeal mask group. Mean arterial to end-tidal carbon dioxide tension differences ranged from 0.13 to 4.13 kPa in the facemask group and from 0-1.73 kPa with the laryngeal mask airway. Pooled data analysis revealed a better correlation between arterial and end-tidal carbon dioxide tensions during laryngeal mask ventilation as compared to facemask breathing. With both techniques the arterial to end-tidal carbon dioxide tension difference was related to respiratory rate and physiological deadspace ventilation. Estimation of arterial carbon dioxide partial pressure by monitoring end-tidal carbon dioxide tension is more reliable with the laryngeal mask airway than during facemask breathing, in particular at small tidal volumes.

Variation in Arterial to End-Tidal CO2 Tension Differences During Anesthesia in the ???Kidney Rest??? Lateral Decubitus Position

The course of arterial to end-tidal carbon dioxide tension difference [P(a-ET)CO2] was evaluated during general anesthesia in 25 patients scheduled for renal surgery performed in the "kidney position." The difference between arterial PCO2 (PaCO2) corrected to body temperature, and end-tidal PCO2 (PETCO2) measured by mass spectrometry was assessed after induction of anesthesia, after placement in the lateral decubitus position with back arched over a kidney bridge ("kidney position"), and every 20 min until the patients were replaced in the supine position at the end of the surgical procedure. Heart rate, arterial blood pressure, and esophageal temperature were simultaneously recorded. After induction of anesthesia, when the patients were lying supine (T1), P(a-ET)CO2 was 4.8 +/- 3.9 mm Hg (mean +/- SD). Placing the patients in the kidney position (T2) induced a significant increase in P(a-ET)CO2 (to 7.9 +/- 3.5 mm Hg; P less than 0.01). These alterations occurred without any significant change in mean arterial blood pressure or heart rate. A progressive increase in mean P(a-ET)CO2 occurred with maintenance of anesthesia; P(a-ET)CO2 reached 8.8 +/- 4.1 mm Hg (P less than 0.05 vs T2) and 8.9 +/- 4.4 mm Hg (P less than 0.05 vs T2) at 65 and 85 min, respectively, after lateral decubitus positioning. Large variations between and within patients were observed. Although stable mean arterial pressure was maintained, these changes were associated with a significant decrease in body temperature. These results demonstrate that P(a-ET)CO2 increases when patients are placed in the kidney position and may vary with the prolongation of anesthesia in this situation.(ABSTRACT TRUNCATED AT 250 WORDS)

The Relationship Between the Arterial to End-tidal Pco2Difference and Hemoglobin Saturation in Patients with Congenital Heart Disease

In right-to-left (RL) intracardiac shunting, the venous blood that is added to the oxygenated blood in the left heart is both poor in oxygen and rich in carbon dioxide. Thus, any given degree of arterial desaturation is associated with an obligatory arterial to end-tidal carbon dioxide tension difference (PaCO2--PETCO2). This paper presents a theoretical analysis of the relationship between PaCO2-PETCO2 and arterial hemoglobin saturation (SaO2) in cyanotic heart disease. Using the shunt equation as a starting point, a curvilinear, negative correlation between PaCO2-PETCO2 and SaO2 can be demonstrated. The slope of the regression of PaCO2--PETCO2 against SaO2 is shown to be positively correlated to Hb concentration, PaCO2, and the respiratory quotient R. The slope of the regression is also slightly increased at relatively high SaO2s and at high inspired oxygen fractions, although these latter factors are of lesser significance. However, in addition to the above primary effects of RL shunting, secondary effects may occur if pulmonary perfusion is reduced sufficiently to cause "alveolar hypoperfusion," which also creates an alveolar dead space. Primary and secondary effects are additive. This theoretical analysis is illustrated with a study of 27 children with congenital heart disease. Their lungs were ventilated with a Servoventilator 900 C, and carbon dioxide single-breath tests were obtained on-line with the use of a computerized system based on the Siemens-Elema carbon dioxide analyzer 930. Blood was sampled for PaCO2 measurement and arterial Hb saturation was measured by pulse oximetry (SpO2).(ABSTRACT TRUNCATED AT 250 WORDS)

Arterial to end‐tidal carbon dioxide tensio difference during laparoscopy Magnitude and effect of anaesthetic technique

The relationship between arterial carbon dioxide tension and end-tidal carbon dioxide tension was studied in 25 patients during laparoscopy. Thirteen patients received general anaesthesia and 12 epidural anaesthesia. The overall mean difference between arterial and end-tidal carbon dioxide tensions was 0.44 kPa (95% confidence intervals 0.28-0.60 kPa) which was significantly less than that reported in studies during other procedures. The reasons for this difference are probably associated with the physiological changes induced by CO2 pneumoperitoneum and steep Trendelenburg positioning. The choice of anaesthetic technique did not affect the arterial to end-tidal carbon dioxide tension difference significantly (p greater than 0.9).

Arterial to End-Tidal Carbon Dioxide Tension Difference During Anaesthesia in Early Pregnancy

Arterial to End-Tidal Carbon Dioxide Tension Difference During Anaesthesia in Early Pregnancy

Arterial to end-tidal carbon dioxide tension difference during anaesthesia in early pregnancy

Sixteen patients requiring general anaesthesia for termination of pregnancy by dilatation and evacuation of the uterus were studied. Arterial and end-tidal carbon dioxide tensions were determined during anaesthesia. The mean arterial to end-tidal carbon dioxide tension difference was 0.07 kPa (-0.02-0.16, 5-95 per cent confidence limits). These results were similar to those observed during Caesarean section and those during anaesthesia for post-delivery tubal ligations. The physiological changes such as increased cardiac output, haemodilution, and increased blood volume which manifest by 12 weeks of gestation probably result in a reduced (a-E')PCO2 value.