Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Capnography”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 811 records · Page 45Linked to original sources
PubMed2006

Noninvasive, automated and continuous cardiac output monitoring by pulmonary capnodynamics: breath-by-breath comparison with ultrasonic flow probe.

BACKGROUND: Cardiac output monitoring is most important where cardiovascular stability is potentially threatened, such as during major surgery and in critically ill patients. However, continuous monitoring of cardiac output is still not performed routinely during anesthesia and critical care, because of invasiveness, expense, and inaccuracy of available technologies. METHODS: A technique termed the capnodynamic method was tested for breath-to-breath measurement of pulmonary blood flow from lung carbon dioxide mass balance, using measured carbon dioxide elimination and end-tidal concentration. A prototype measurement system was constructed for a feasibility study in six anesthetized sheep. Large and rapid fluctuations in cardiac output were generated by repeated dobutamine and esmolol challenge. Measurements were compared with an indwelling ultrasonic flow probe placed on the ascending aorta or pulmonary artery. RESULTS: Cardiac output measured by the flow probe varied between zero and 8.67 l/min, with a mean of 3.50 l/min. Overall mean bias [SD of the difference] between the methods (capnodynamic - flow probe) was -0.25 [0.94] l/min, r = 0.79 (P < 0.001). During periods of stability in cardiac output of 5 min or more, mean bias was -0.20 [0.55] l/min. The method successfully indicated two cardiac arrest events, which were induced in one of the animals. CONCLUSIONS: The method satisfactorily tracked wide fluctuations in cardiac output in real time. The capnodynamic method may have potential for continuous noninvasive cardiac output monitoring in patients undergoing anesthesia for major surgery, and in critical care, on a routine basis.

Animals↗
PubMed1997

Continuous assessment of gastric intramucosal PCO2 and pH in hemorrhagic shock using capnometric recirculating gas tonometry.

OBJECTIVES: To test a novel device for continuous monitoring of gut intramucosal PCO2 and pH and to compare its use with conventional intermittent saline balloon-tonometry in a model of hemorrhagic shock. DESIGN: A prospective animal study. SETTINGS: A university research laboratory. SUBJECTS: Eight anesthetized, mechanically ventilated mongrel dogs. INTERVENTIONS: Two balloon-tip tonometry catheters, one conventional and one modified for continuous recirculating gas tonometry, were inserted into each animal's stomach by the oral route. Gastric intramucosal PCO2 was recorded continuously by capnometric recirculating gas tonometry throughout the experiment. After a baseline period of 90 mins, vital signs, arterial and mixed venous blood gases, and intramucosal PCO2 values were obtained by recirculating gas tonometry and by the conventional method. Using a modified Wiggers' model, the animals were then subjected to hemorrhage of up to 45 mL/kg, or the volume required to effect a decrease in mean arterial pressure to < 30 mm Hg. After 30 mins, the shed blood was reinfused and the experiment continued for an additional 30 mins. Vital signs, arterial and mixed venous blood samples, saline tonometry samples, and recirculating gas tonometry readings were obtained immediately before and 30 mins after reinfusion of blood. MEASUREMENTS AND MAIN RESULTS: Mean +/- SD baseline intramucosal PCO2 was 47.6 +/- 9.5 torr (6.3 +/- 1.3 kPa) by capnometric recirculating gas tonometry and 45.8 +/- 3.4 torr (6.1 +/- 0.5 kPa) by conventional saline tonometry (p = NS). By 5 mins after inducing hemorrhage, intramucosal PCO2 by recirculating gas tonometry had increased significantly (49.3 +/- 9.7 torr [6.6 +/- 1.3 kPa]; p < .05), and by 30 mins, it had increased to 59.7 +/- 11.3 torr (8.0 +/- 1.5 kPa; p < .001 compared with baseline). After 30 mins of hemorrhage, the conventional method showed an increase in intramucosal PCO2 to 63.0 +/- 20.9 torr (8.4 kPa +/- 2.8 kPa; p = NS vs. baseline by conventional method; p = NS vs. corresponding recirculating gas tonometry values). Gastric intramucosal pH, as determined by recirculating gas tonometry, decreased significantly at 5 mins after starting hemorrhage (7.13 +/- 0.10 to 7.10 +/- 0.10, p < .02). After 30 mins of hemorrhage, intramucosal pH decreased to 6.88 +/- 0.14 (from 7.10 +/- 0.10) by the conventional saline tonometry technique (p < .01) and to 6.89 +/- 0.10 by recirculating gas tonometry (p < .001 vs. baseline). Intramucosal PCO2 by both techniques remained significantly increased above baseline values 30 mins after reinfusion of the shed blood. CONCLUSIONS: Capnometric recirculating gas tonometry allows continuous and automated assessment of gastrointestinal tract perfusion by providing on-line measurements of intramucosal PCO2, which can also be used to derive intramucosal pH. The technique is able to detect changes in intramucosal PCO2 in response to an induced insult over intervals as short as 5 mins.

Animals↗
PubMed1997

Noninvasive capnometry monitoring for respiratory status during pediatric seizures.

OBJECTIVE: To determine the reliability and clinical value of end-tidal CO2 by oral/nasal capnometry for monitoring pediatric patients presenting post ictal or with active seizures. DESIGN: Clinical, prospective, observational study. SETTING: University affiliated children's hospital. INTERVENTIONS: One hundred sixty-six patients (105 patients with active seizures, 61 post ictal patients) had end-tidal CO2 obtained by oral/nasal sidestream capnometry, and respiratory rates, oxygen saturation, and pulse rates recorded every 5 mins until 60 mins had elapsed. End-tidal CO2 values were compared with a capillary PCO2 and clinical observation. MEASUREMENTS AND MAIN RESULTS: The mean end-tidal CO2 reading was 43.0 +/- 11.8 torr [5.7 +/- 1.6 kPa] and the mean capillary PCO2 reading was 43.4 +/- 11.7 torr [5.7 +/- 1.6 kPa]. The correlation between end-tidal CO2 and capillary PCO2 was significant (r2 = .97; p < .0001). A relative average bias of 0.33 torr (0.04 kPa) with end-tidal CO2 lower than capillary PCO2 was established with 95% limits of agreement +/-4.2 torr (+/-0.6 kPa). Variability of difference scores was not related to range of mean scores (r2 = .00003), age (r2 = .0004), or respiratory rates (r2 = .0009). End-tidal CO2 (r2 = .22; p < .001) correlated better with respiratory rate changes when compared with oxygen saturation (r2 = .02; p = .01). CONCLUSIONS: Dependable end-tidal CO2 values can be obtained in pediatric seizure patients using an oral/nasal cannula capnometry circuit. Continuous end-tidal CO2 monitoring provides the clinician with a reliable assessment of pulmonary status that can assist with decisions to provide ventilatory support.

Adolescent↗
PubMed1998

Portable devices used to detect endotracheal intubation during emergency situations: a review.

OBJECTIVES: To review the operational characteristics of commercial devices used to detect endotracheal intubation; and to identify an ideal device for detecting endotracheal intubation in emergency situations, especially in the prehospital setting during cardiac arrest. DATA SOURCES: Relevant articles from the medical literature are referenced. STUDY SELECTION: The authors identified the need for understanding the basic operation principles of portable devices used to detect endotracheal intubation and to correctly use them in unpredictable clinical situations. DATA EXTRACTION: Data from published literature. DATA SYNTHESIS: Recently, a number of new portable devices have been marketed for detecting endotracheal intubation, each having advantages and disadvantages, especially when used during emergency situations. The devices are classified based on their principle of operation. Some rely on CO2 detection (STATCAP, Easy Cap, and Pedi-Cap), others utilize the transmission of light (Trachlight, SURCH-LITE), one operates based on reflection of sound energy (SCOTI), and some depend on aspiration of air (TubeChek and TubeChek-B). A brief description of each device and its operational characteristics are reviewed. A comparative analysis among the devices is made based on size, portability, cost, ease of operation, need for calibration or regular maintenance, reliability for patients with and without cardiac arrest, and the possibility of use for adult and pediatric patients. False-negative and false-positive results for each device are also discussed. False-negative results mean that although the endotracheal tube is in the trachea, the device indicates it is not. False-positive results mean that although the endotracheal tube is in the esophagus, the device indicates it is in the trachea. CONCLUSIONS: Although no clinical comparative study of commercial devices to detect endotracheal intubation exists, the syringe device (TubeChek) has most of the characteristics necessary for a device to be considered ideal in emergency situations in the prehospital setting. It is simple, inexpensive, easy to handle and operate, disposable, does not require maintenance, gives reliable results for patients with and without cardiac arrest, and can be used for almost all age groups. The device may yield false-negative results, most commonly in the presence of copious secretions and in cases of accidental endobronchial intubation. Regardless of the device used, clinical judgment and direct visualization of the endotracheal tube in the trachea are required to unequivocally confirm proper endotracheal tube placement.

Capnography↗
PubMed1999

Sublingual capnometry: a new noninvasive measurement for diagnosis and quantitation of severity of circulatory shock.

OBJECTIVE: To investigate the feasibility and predictive value of sublingual Pco2 (P(SL)CO2) measurements as a noninvasive and early indicator of systemic perfusion failure. DESIGN: A prospective, criterion study. SETTING: Emergency department and medical and surgical intensive care units of an urban community medical center. PARTICIPANTS AND PATIENTS: Five normal human volunteers and 46 patients with acutely life-threatening illness or injuries. INTERVENTIONS: Intra-arterial or automated cuff blood pressure and arterial blood lactate (LAC) were measured concurrently with P(SL)CO2. RESULTS: P(SL)CO2 in five healthy volunteers was 45.2 +/- 0.7 mm Hg (mean +/- sD). Twenty-six patients with physical signs of circulatory shock and LAC >2.5 mmol/L had a P(SL)CO2 of 81 +/- 24 mm Hg. This contrasted with patients admitted without clinical signs of shock and LAC of <2.5 mmol/L who had a P(SL)CO2 of 53 +/- 8 mm Hg (p < .001). The initial P(SL)CO2 of 12 patients who died before recovery from shock was 93 +/- 27 mm Hg, and this contrasted with 58 +/- 11 mm Hg (p < .001) in hospital survivors. Increases in P(SL)CO2 were correlated with increases in LAC (r2 = .84; p < .001). When P(SL)CO2 exceeded a threshold of 70 mm Hg, its positive predictive value for the presence of physical signs of circulatory shock was 1.00. When it was <70 mm Hg, it predicted survival with a predictive value of 0.93. CONCLUSION: P(SL)CO2 may serve as a technically simple and noninvasive clinical measurement for the diagnosis and estimation of the severity of circulatory shock states.

Adolescent↗
PubMed2000

End-tidal carbon dioxide as a noninvasive indicator of cardiac index during circulatory shock.

OBJECTIVE: To document the relationships between cardiac index and end-tidal carbon dioxide tension (PetCO2 during diverse low-flow states of circulatory shock. DESIGN: Randomized, prospective, controlled studies on animal models of hemorrhagic, septic, and cardiogenic shock. SETTING: University-affiliated research laboratory. SUBJECTS: Sixteen anesthetized domestic pigs weighing 35-45 kg. INTERVENTIONS: Hemorrhagic shock was induced in five pigs by bleeding followed by reinfusion of shed blood. Septic shock was induced in five pigs by infusion of live Escherichia coli. Cardiogenic shock followed an interval of global myocardial ischemia after inducing and reversing ventricular fibrillation in six pigs. MEASUREMENTS AND MAIN RESULTS: PetCO2 was continuously measured. Cardiac index was measured intermittently by using conventional thermodilution techniques. Cardiac index was correlated with PetCO2 by polynomial regression and Bland-Altman analyses. PetCO2 was highly correlated with cardiac index during hemorrhagic shock (r2 = .69, p < .01), septic shock (r2 = .65, p < .01), and cardiogenic shock (r2 = .81, p < .01). PetCO2 predicted thermodilution cardiac index with bias of -11+/-27 (+/-2 SD) mL/min/kg during hemorrhagic shock, 1.3+/-20.4 (+/- 2 SD) mL/min/kg during septic shock, and -1+/-12 (+/-2 SD) mL/min/kg during cardiogenic shock. CONCLUSIONS: Cardiac output and PetCO2 were highly related in diverse experimental models of circulatory shock in which cardiac output was reduced by >40% of baseline values. Therefore, measurement of PetCO2 is a noninvasive alternative for continuous assessment of cardiac output during low-flow circulatory shock states of diverse causes.

Animals↗