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At least 217 records · Page 12Linked to original sources
PubMed2004

Capnography as a predictor of the return of spontaneous circulation.

EtCO2 monitoring is a valuable tool for clinical management of patients in cardiac arrest, near-arrest and post-arrest. During cardiac arrest, EtCO2 levels fall abruptly at the onset of cardiac arrest, increase after the onset of effective CPR and return to normal at return of spontaneous circulation (ROSC). During effective CPR, end-tidal CO2 has been shown to correlate with cardiac output, coronary perfusion pressure, efficacy of cardiac compression, ROSC and even survival. Colorimetric detectors (shown to correlate with infrared capnometry) have been shown to have prognostic value in both adult and pediatric CPR. The higher the initial value of EtCO2, the greater was short-term survival. EtCO2 is a useful tool during patient resuscitation for evaluating the current and potential effects of treatment, and could be potentially useful in determining when to terminate resuscitation efforts.

Capnography↗
PubMed1998

Interpretation of capnography.

The anesthetist will get the most information out of a capnograph if it is examined systematically. First, the anesthetist must determine whether exhaled CO2 (i.e., a waveform) is present. The differential diagnosis of absent CO2 includes esophageal intubation, accidental tracheal extubation, disconnection of the breathing circuit, complete obstruction of the endotracheal tube or conducting system (kink, inspissated blood or secretions, extremely severe bronchospasm) or of the breathing circuit, apnea, and cardiac arrest. Second, the shape of the waveform must be analyzed systematically by looking at, and in sequence, phase I (inspiratory baseline, which should be zero); phase II (expiratory upstroke, which should be nearly perpendicular to the inspiratory baseline); phase III (expiratory or alveolar plateau, which should be a straight, nearly horizontal, line); and phase IV (inspiratory downstroke, which should be nearly perpendicular to the inspiratory baseline). This discussion will follow this systematic approach but will emphasize diagnosis that can be obtained from the phase III alveolar plateau.

Bronchial Spasm↗
PubMed1991

Capnography for detection of endobronchial migration of an endotracheal tube.

A patient is described in whom migration of an endotracheal tube into the right main bronchus was suspected when end-tidal carbon dioxide suddenly decreased from 28 to 22 mm Hg. Acute changes with migration of the endotracheal tube into the main bronchus were also studied in an animal experimental model. End-tidal carbon dioxide decreased and tracheal (inflation) pressure increased, with no change in tidal volume. Arterial blood gases showed time-dependent decreases in pH and oxygen tension and an increase in carbon dioxide tension.

Aged↗
PubMed1987

Capnography and the Bain circuit II: Validation of a computer model.

Validation of a computer model is described. The behavior of this model is compared both with mechanical ventilation of a test lung in a laboratory setup that uses a washout method and with manual ventilation. A comparison is also made with results obtained from a volunteer breathing spontaneously through a Bain circuit and with results published in the literature. This computer model is a multisegment representation of the Bain circuit and connecting tubing. For each segment, gas pressure, gas volume flow, and partial pressure of carbon dioxide are calculated for any number of breaths wanted. As a result, the time course of these variables can be generated for any location or, conversely, the carbon dioxide distribution in the system can be calculated for any time instant. A test lung, the human lungs, the ventilator bellows, and the reservoir bag are each represented by a single segment. The shapes of pressure and flow curves and of the capnograms taken at different locations in the Bain tubing are in good agreement. The washout study permits measurement of the time delay between the first expiration and the arrival of carbon dioxide at a particular location. The carbon dioxide level in the test lung decreases during inspiration and is stable during expiration. Quantitative agreement between model and experimental transport delays and carbon dioxide levels is such that the differences can be explained by the inaccuracy of the measurement. This is concluded from a sensitivity analysis. The study of the effect of segment size shows an almost optimal agreement between model behavior and experimental results for a 36-segment model. Execution of a thorough validation is imperative before such models can be used for clinical management and decision making or for teaching.

Airway Resistance↗
PubMed1985

Capnography and the Bain circuit I: A computer model.

The Mapleson D anesthesia breathing system has no valves and allows rebreathing of carbon dioxide. Its coaxial version is known as the Bain system. The interpretation of capnograms obtained during its use requires an understanding of the interrelationships of patient and system variables. Toward that end, a systematic description of mechanical ventilation with the Bain circuit was undertaken based on the physical laws of gas transport. The mathematical formulation of the model contains the relations between pressure, flow, and volume in the tube, alveolar space, and ventilator. The flows, calculated from these relations, are used to determine the CO2 concentrations in the different parts of the model. Two sets of data are used--patient and system. The patient data, used to solve the equations numerically, are lung-thorax compliance, CO2 inflow into alveolar space (CO2 production), functional residual capacity, dead space volume, airway resistance, and respiratory quotient. The ventilation system data comprise the dimensions and volumes of the Bain circuit, ventilator, connectors, and tubes; spill valve pressure; resistances to flow in the individual tube parts; ventilator settings; and fresh-gas flow rates. After incorporation of a volunteer's respiratory variables into the model, capnograms obtained from the model compared well with those obtained from the volunteer. The structure of the model is such that it permits easy introduction or changes of patient and system variables to obtain individual results or model specific circumstances. This flexibility makes it a useful tool for understanding the properties of the Bain circuit under a variety of clinical circumstances. The results may be displayed in a number of different ways.

Anesthesia, General↗
PubMed1984

Capnography in the early diagnosis of carbon dioxide embolism during laparoscopy.

Venous embolism of carbon dioxide occurred during elective diagnostic laparoscopy in a healthy adult female. The diagnosis of gas embolism was made on the basis of the sudden abrupt onset of systolic and diastolic murmurs. The continuously recorded end-tidal carbon dioxide concentration (FETCO2) increased abruptly from 3.8 to 4.2 per cent and then slowly decreased to 4.0 per cent over the subsequent 30 seconds. CO2 insufflation was terminated immediately following the establishment of the diagnosis. The patient recovered uneventfully. A transient but rapid rise in FETCO2 is suggested as a useful early sign of venous CO2 embolism during laparoscopy.

Adult↗
PubMed1992

Utility of capnography in predicting venous carbon dioxide partial pressure in sedated patients during outpatient oral surgery.

Twelve ASA class I patients scheduled for removal of third molars under intravenous sedation were included in the study. Samples for venous blood gas analysis were drawn every 5 minutes and the venous partial pressure of carbon dioxide was compared to the end-tidal CO2 recorded from a modified nasal cannula at the same time the samples were drawn. Correlation analysis was performed using the Pearson correlation coefficient. The overall correlation between end-tidal CO2 and PVCO2 was .54 (P = .0001). The results of the investigation indicate that through simple modifications of the end-tidal CO2 monitoring device, the correlation between end-tidal CO2 and serum PCO2 in a nonintubated patient can be improved.

Adolescent↗
PubMed1995

[Diagnosis of heart arrest caused by CO2 embolism during laparoscopic surgery by monitoring of aortic blood flow and capnography].

We report the case of a 25-year-old woman undergoing a laparoscopic cholecystectomy, who suffered, one min after the beginning of intraperitoneal insufflation of CO2 (2.5 L at a pressure of 10 mmHg), a sudden decrease to 0.8 L.min-1 of the aortic blood flow (ABF), monitored in the descending aorta by an oesophageal echo-Doppler probe, associated with a decrease of PetCO2 to 15 mmHg and of SpO2 readings to 88%. Despite the lack of simultaneous changes in heart rate and arterial pressure, pulmonary gas embolism (GE) was suspected. The pneumoperitoneum was exsufflated and CPR was started because of circulatory inefficiency. Ten min later, efficient spontaneous cardiac activity restarted, whereas PetCO2 and ABF returned rapidly to normal values. At this time, a typical gas noise was clearly obtained through the oesophageal Doppler transducer. The patient remained in deep coma (GCS:6) with a left sided hemiplegia. However, she fully recovered after four sessions of hyperbaric oxygenation. Simultaneous continuous monitoring of ABF and PetCO2 allows an undelayed recognition of major circulatory disturbances, before significant changes in heart rate and arterial pressure occur.

Adult↗
PubMed1987

[Capnography].

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Anesthesia↗