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At least 721 records · Page 40Linked to original sources
PubMed2000

End-tidal CO2 pressure determinants during hemorrhagic shock.

OBJECTIVES: To examine the relationship between end-tidal CO2 (PETCO2) and its physiological determinants, pulmonary blood flow (cardiac output, CO) and CO2 production (VCO2), in a model of hemorrhagic shock during fixed minute ventilation. DESIGN AND SETTING: Prospective, observational study in a research laboratory at a university center. SUBJECTS AND INTERVENTIONS: Six anesthetized, intubated, and mechanically ventilated mongrel dogs. Progressive stepwise bleeding. MEASUREMENTS AND RESULTS: We continuously measured PETCO2 with a capnograph, pulmonary artery blood flow with an electromagnetic flow probe, arterial oxygen saturation (SaO2) with a fiberoptic catheter, and oxygen consumption (VO2) and VCO2 by expired gases analysis. Oxygen delivery (DO2) was continuously calculated from pulmonary blood flow and SaO2. We studied the correlation of PETCO2 with CO and VCO2 in each individual experiment. We also calculated the critical point in the relationships PETCO2/ DO2 and VO2/DO2 by the polynomial method. As expected, PETCO2 was correlated with CO. The best fit was logarithmic in all experiments (median r2 = 0.90), showing that PETCO2 decrease is greater in lowest flow states. PETCO2 was correlated with VCO2, but the best fit was linear (median r2 = 0.77). Critical DO2 for PETCO2 and VO2 was 8.0 +/- 3.3 and 6.3 +/- 2.5 ml x min(-1) kg(-1), respectively (NS). CONCLUSIONS: Our data reconfirm the relationship between PETCO2 and CO during hemorrhagic shock. The relatively greater decrease in PETCO2 at lowest CO levels could represent diminished CO2 production during the period of VO2 supply dependency.

Animals↗
PubMed2004

Mapping hypercapnia-induced cerebrovascular reactivity using BOLD MRI.

Severe carotid artery stenosis or occlusion may put patients at risk for ischaemic stroke. Reduced cerebrovascular reserve capacity is a possible indicator of an imminent ischaemic event and can be determined by assessment of cerebrovascular reactivity to a vasodilative stimulus. However, little is known about the distribution of cerebrovascular reactivity in healthy individuals. In 13 healthy volunteers, dynamic T2* MR images, acquired at alternating inspiratory pCO2 levels, showed a high percentage of signal change in grey matter, with a strong linear correlation with end-tidal pCO2. The mean percentages of signal change for grey and white matter were 5.9 +/- 1.2% and 1.9 +/- 0.5%, respectively. The mean time lag between CO2 stimulus and haemodynamic response was 15 +/- 4 s for grey matter and 180 +/- 12 s for white matter. Parameter mapping revealed a hemispherically symmetrical and homogeneous distribution of cerebrovascular reactivity over the entire grey matter. These findings indicate that it may be feasible to detect exhausted cerebrovascular autoregulation in patients with a compromised cerebral vasculature.

Adult↗
PubMed2003

Accuracy of portable quantitative capnometers and capnographs under prehospital conditions.

This study was designed to assess the pCO(2) accuracy of portable mainstream (Tidal Wave, Novametrix; Propaq 106, Protocol) and sidestream capnometers (Capnocheck 8200, BCI; Capnocount mini, Weinmann; NPB-75, Nellcor Puritan Bennett; SC-210, Pryon) with respect to international standards and preclinical emergency conditions. Measurements were performed under temperature conditions of +22 degrees C and -20 degrees C using dry gas mixtures with different CO(2) concentrations (STPD) and in patients ventilated with pure oxygen (BTPS). Accuracy presented to be between +1% (Capnocheck) and +12% (Propaq) (STPD) and between -0.4% (Capnocheck) and +11% (Tidal Wave) (BTPS). The measurements were affected by low ambient temperature only in the NPB-75 (+15%). Our results indicate that portable quantitative capnometers are able to fulfill accuracy requirements as requested by international standards but can be affected by changing ambient temperatures.

Capnography↗
PubMed2004

Evaluation of an end-tidal portable ETCO2 colorimetric breath indicator (COLIBRI).

Evaluation of tube position is important after in-hospital and prehospital emergency intubation. Colorimetric breath indicators are devices for immediate control of tube positioning by showing a color change according to end-tidal CO2 (ETCO2) concentrations. We hypothesized that colorimetric breath indicators can yield reliable results for confirmation of tube position. The aim of this study was to evaluate the effectiveness and safety of a new colorimetric breath indicator (Colibri, ICOR AB, Bromma, Sweden) in 147 patients during general anesthesia, in critically ill patients, during transport to in-hospital interventions, and in a study design after insertion of a second tube into the esophagus in long-term ventilated patients. The Colibri was attached between the respective airway and ventilatory tubing. Seventy-three patients were investigated during general anesthesia, 39 patients were observed during long-term ventilation with an average duration of 33 hours, in 15 patients during transport to an intervention for up to 4 hours, and in 20 long-term ventilated patients at the medical intensive-care unit after insertion of a second tube intentionally into the esophagus with the help of a laryngoscope. The Colibri worked well in all groups investigated and showed no false results in the group with tubes inserted into the trachea and esophagus. Data suggest that the Colibri might serve as a valuable tool for evaluating and controlling tube position. This device is independent of power supply or electronic equipment, portable, small, and immediately ready for use.

Adolescent↗
PubMed2005

The effectiveness of out-of-hospital use of continuous end-tidal carbon dioxide monitoring on the rate of unrecognized misplaced intubation within a regional emergency medical services system.

STUDY OBJECTIVE: We evaluate the association between out-of-hospital use of continuous end-tidal carbon dioxide (ETCO2) monitoring and unrecognized misplaced intubations within a regional emergency medical services (EMS) system. METHODS: This was a prospective, observational study, conducted during a 10-month period, on all patients arriving at a regional Level I trauma center emergency department who underwent out-of-hospital endotracheal intubation. The regional EMS system that serves the trauma service area is composed of multiple countywide systems containing numerous EMS agencies. Some of the EMS agencies had independently implemented continuous ETCO2 monitoring before the start of the study. The main outcome measure was the unrecognized misplaced intubation rate with and without use of continuous ETCO2 monitoring. RESULTS: Two hundred forty-eight patients received out-of-hospital airway management, of whom 153 received intubation. Of the 153 patients, 93 (61%) had continuous ETCO2 monitoring, and 60 (39%) did not. Forty-nine (32%) were medical patients, 104 (68%) were trauma patients, and 51 (33%) were in cardiac arrest. The overall incidence of unrecognized misplaced intubations was 9%. The rate of unrecognized misplaced intubations in the group for whom continuous ETCO2 monitoring was used was zero, and the rate in the group for whom continuous ETCO2 monitoring was not used was 23.3% (95% confidence interval 13.4% to 36.0%). CONCLUSION: No unrecognized misplaced intubations were found in patients for whom paramedics used continuous ETCO2 monitoring. Failure to use continuous ETCO2 monitoring was associated with a 23% unrecognized misplaced intubation rate.

Adolescent↗
PubMed2006

The role of carbon dioxide detectors for confirmation of endotracheal tube position.

There is evidence that practitioners who are responsible for airway management at newborn resuscitations may place an endotracheal tube incorrectly with confidence. Moving on to the further stages of resuscitation, without managing the airway adequately, and commencing ventilation has the potential for significant harm to the baby. Because primary confirmation is fallible, there is a need for secondary confirmation of correct endotracheal tube placement and effective airway and breathing before moving on to cardiovascular support. Symmetric chest movement, auscultation, exhaled carbon dioxide (CO(2)), and an increase in heart rate have been suggested as providing secondary confirmation. Measurement of exhaled CO(2) is accepted widely as a standard of care in adult and pediatric intensive care and in anaesthetized patients.

Capnography↗
PubMed2006

Transcutaneous monitoring of partial pressure of carbon dioxide in the elderly patient: a prospective, clinical comparison with end-tidal monitoring.

STUDY OBJECTIVE: To evaluate the accuracy and precision of estimation of partial pressure of carbon dioxide (Pa(CO2)) using end-tidal or transcutaneous CO2 (TcP(CO2)) measurements during mechanical ventilation in the elderly patient. DESIGN: A prospective, observational study was conducted. SETTINGS: The study was done in the anesthesia department of a university hospital. PATIENTS: Seventeen anesthetized, mechanically ventilated patients older than 60 years were studied. INTERVENTIONS AND MEASUREMENTS: During standard sevoflurane anesthesia, and after proper calibration and an equilibration time of 30 minutes with stable hemodynamic and respiratory variables, arterial (Pa(CO2)), end-tidal (Pet(CO2)), and transcutaneous (TcP(CO2)) CO2 partial pressures were determined. In each patient, 1 to 5 sample sets (Pa(CO2), Pet(CO2), and TcP(CO2)) were obtained. MAIN RESULTS: A total of 45 sample sets were obtained from the patients studied. The Pa(CO2) values ranged between 21 and 58 mm Hg. The Pa(CO2) - Pet(CO2) tension gradient was 6 +/- 5 mmHg (95% confidence interval, -3 to 16 mmHg), whereas the Pa(CO2) - TcP(CO2) tension gradient was 2 +/- 4 mmHg (95% confidence interval, -6 to 9 mmHg) (P = 0.0005). The absolute value of the difference between Pa(CO2) and Pet(CO2) was 3 mm Hg or less in 7 of 45 sample sets (15%), whereas the absolute value of the difference between Pa(CO2) and TcP(CO2) was 3 mm Hg or less in 21 of 45 sample sets (46%) (P = 0.003). Linear regression analysis for TcP(CO2) versus Pa(CO2) showed a slope of 0.84 (r(2) = 0.73), whereas the linear regression analysis for Pet(CO2) versus Pa(CO2) showed a slope of 0.54 (r(2) = 0.50). CONCLUSION: Transcutaneous monitoring of CO(2) partial pressure gives a more accurate estimation of arterial CO(2) partial pressure than does Pet(CO2) monitoring.

Aged↗
PubMed2005

The effect of vinegar on colorimetric end-tidal carbon dioxide determination after esophageal intubation.

This study examines the effect of vinegar placement in the stomach on colorimetric end-tidal carbon dioxide (ETCO(2)) determinations after esophageal intubation. Using a blinded, prospective, before and after post-mortem swine model, colorimetric ETCO(2) was determined after aspiration of the stomach contents and after placement of aliquots of saline and vinegar. Data were compiled from 12 swine within 120 min post-mortem. In 12 of 12 trials, the ETCO(2) detector turned yellow, indicating "positive" determination of CO(2), but did not return to "purple" with multiple insufflations with 100% O(2). We conclude that esophageal intubation with a small amount of vinegar in the stomach can cause an irreversible color change of the detector to yellow. Color change indicating the presence of carbon dioxide without subsequent color change back to purple with insufflation with 100% oxygen should arouse suspicion of improper placement of the endotracheal tube.

Acetic Acid↗
PubMed2001

A comparison of the hemodynamic and metabolic effects of extraperitoneal carbon dioxide and nitrous oxide insufflation.

BACKGROUND: The aim of the present study was to compare the hemodynamic and metabolic effects of extraperitoneal carbon dioxide (CO(2)) and nitrous oxide (N(2)O) insufflation. MATERIAL AND METHODS: Fourteen dogs were used in the experiment. All the animals were intubated under general anesthesia. A catheter was placed into the right jugular vein for central venous pressure (CVP), pulmonary artery pressure (PAP), pulmonary wedge pressure (PWP), and heart rate (HR) monitorization. End-tidal CO(2) pressure was measured by a capnometer connected to the endotracheal tube. Another catheter was inserted into the left femoral artery for arterial blood gas analysis and blood pressure monitorization. The preperitoneal dissection was made from a 1.5 cm subumbilical incision by using a preperitoneal dissection balloon. A laparoscope was placed in the preperitoneal space and the gas insufflation was kept at a constant pressure of 12 mm Hg throughout the experiment. All the study parameters were measured at the beginning of the insufflation and at every 15 minutes for 1 hour. RESULTS: Mean artery pressure increased with time in both groups, but the increase was only significant in the CO(2) group. PWP, CVP, PAP, and HR increased slightly in both groups, but there was no significant difference between the groups. The end-tidal CO(2) increased in the CO(2) group but decreased from the baseline in the N(2)O group. A significant acidosis was observed in only the CO(2) group. PaCO(2) significantly increased in the CO(2) group; hence, PaCO(2) slightly decreased in N(2)O group. The difference between the groups was significant. CONCLUSIONS: N(2)O insufflation of the extraperitoneal space in dogs avoided the unwanted metabolic and hemodynamic side effects of CO(2) insufflation. Thus, N(2)O insufflation in the extraperitoneal space is a safer alternative to CO(2) insufflation experimentally, and can be preferred especially in patients with cardiac and pulmonary diseases.

Animals↗