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 55 records · Page 3Linked to original sources
PubMed2003

Accuracy of pulse oximetry and capnography in healthy and compromised horses during spontaneous and controlled ventilation.

The objective of this prospective clinical study was to evaluate the accuracy of pulse oximetry and capnography in healthy and compromised horses during general anesthesia with spontaneous and controlled ventilation. Horses anesthetized in a dorsal recumbency position for arthroscopy (n = 20) or colic surgery (n = 16) were instrumented with an earlobe probe from the pulse oximeter positioned on the tip of the tongue and a sample line inserted at the Y-piece for capnography. The horses were allowed to breathe spontaneously (SV) for the first 20 min after induction, and thereafter ventilation was controlled (IPPV). Arterial blood, for blood gas analysis, was drawn 20 min after induction and 20 min after IPPV was started. Relationships between oxygen saturation as determined by pulse oximetry (SpO2), arterial oxygen saturation (SaO2), arterial carbon dioxide partial pressure (PaCO2), and end tidal carbon dioxide (P(et)CO2), several physiological variables, and the accuracy of pulse oximetry and capnography, were evaluated by Bland-Altman or regression analysis. In the present study, both SpO2 and P(et)CO2 provided a relatively poor indication of SaO2 and PaCO2, respectively, in both healthy and compromised horses, especially during SV. A difference in heart rate obtained by pulse oximetry, ECG, or palpation is significantly correlated with any pulse oximeter inaccuracy. If blood gas analysis is not available, ventilation to P(et)CO2 of 35 to 45 mmHg should maintain the PaCO2 within a normal range. However, especially in compromised horses, it should never substitute blood gas analysis.

Anesthesia, General↗
PubMed1995

Capnography.

Capnography measures exhaled carbon dioxide and is most useful when applied directly to patient care. This is in circumstances of detecting misplacement of the tracheal tube, dysfunction of respiratory apparatuses, detection of abnormal lung function, successful cardiopulmonary resuscitation, and trending of deadspace changes. The least reliable application is to reflect alveolar ventilation (PaCO2). This application is most common during general anesthesia and weaning from mechanical ventilation. Provided the patient has a stable cardiac status, stable body temperature, absence of lung disease, and normal capnogram, PETCO2 monitoring may assist in estimating PaCO2. The use of capnography in patients with severe respiratory failure should be applied with careful reflection. The increased V/Q mismatch that is consistent with a widened P(a-ET) gradient, as well as worsening hypercapnea with increased peripheral carbon dioxide production, can lead to erroneous PETCO2 values. Capnography may be least useful in the sickest patients.

Capnography↗
PubMed1991

End-tidal carbon dioxide pressure in neonates and infants measured by aspiration and flow-through capnography.

In 25 anesthetized, intubated, artificially ventilated, and paralyzed healthy neonates and infants, end-tidal PCO2 (PETCO2) measured by remote multiplexed mass spectrometry was 1.86 +/- 1.58 mm Hg lower than arterial PCO2 (PaCO2). PETCO2 measured by a flow-through cuvette was 1.02 +/- 1.64 mm Hg lower than PaCO2. The difference between the two methods of capnography was not significant. Values for PETCO2 obtained by mass spectrometry changed -0.43 +/- 1.43 mm Hg from baseline after 15 minutes of aspiration at a sample flow rate of 240 ml/min. Values for PETCO2 obtained with flow-through capnography changed -0.17 +/- 2.17 mm Hg from baseline after 15 minutes. In both methods, the changes from baseline in PETCO2 over time were not significant. These results suggest that both methods of capnography studied are reliable and may be used safely in neonates despite high sample flow rates and added apparatus dead space (0.6 ml for tracheal tubes less than or equal to 4.0 mm OD and 4.9 ml for tracheal tubes greater than 4.0 mm OD).

Carbon Dioxide↗
PubMed1994

An introduction to capnography.

The aim of this article is to present an overview of the practical aspects of capnography and to define its uses and limitations. Modern rapid-response infrared CO2 analyzers are able to follow changes in CO2 concentrations within a single breath and have, therefore, gained wide clinical acceptance for respiratory monitoring and for studying aspects of respiratory control. Their use for the estimation of mean arterial CO2 tensions is limited, however, to individuals with normal lungs during resting metabolic states. They also require careful calibration taking barometric and water vapor pressure into account. Commonly encountered technical problems in capnography are condensation of water vapor and mucus plugging in the sampling tubes as well as poor recordings as a result of faulty connections and electrical interference. These can be minimized through selection and careful setting up of the most appropriate equipment for prevailing conditions. Despite some marked limitations, capnography can be a valuable tool in the assessment of ventilatory state and some aspects of respiratory control.

Carbon Dioxide↗
PubMed1991

Evaluation of the clinical usefulness of capnography curves during a hyperventilation provocation test in the diagnosis of hyperventilation syndrome.

We evaluated the diagnostic usefulness of capnography curves during and following a hyperventilation provocation test (HVPT) in the hyperventilation syndrome (HVS). The diagnosis of HVS was based on the Nijmegen questionnaire and on the reproduction of symptoms during HVPT. Capnography curves of 40 HVS patients, 40 non-HVS patients with psycho-somatic complaints and 26 healthy controls were analyzed. There was no difference in baseline end-tidal CO2-level (FETCO2) between the 3 groups. The spontaneous fall of FETCO2 during the adaptation phase was clearly different in HVS patients versus non-HVS patients or controls: -0.12 mmol/l (95% confidence limits -0.18 to -0.06) versus +0.01 mmol/l (95% confidence limits -0.04 to +0.16) (p = 0.002). The 3 minutes FETCO2 recovery ratio and the 5 minutes ratio were not significantly different between the groups. In conclusion, in this study the spontaneous fall of FETCO2 during the adaptation phase of the HVPT was the only valuable part of the capnography test to discriminate between HVS and non-HVS patients.

Carbon Dioxide↗
PubMed1988

Capnography in mechanically ventilated patients.

Capnography, the science of CO2 waveforms analysis, can play a role in the management of mechanically ventilated patients. Mass spectrometers are the devices most commonly used to collect sequentially and examine CO2 waveforms from multiple patients in the ICU or operating rooms. We present here a review of some clinical and technical problems, which may be resolved efficiently and expeditiously through the use of mass spectrometry and capnography. Mechanical failures, especially those that lead to rebreathing of exhaled gases, can be readily detected. The patient's progress during weaning and the consequences of changes in mechanical assistance can be virtually and noninvasively determined. An expanded role of capnography in mechanically ventilated patients can increase the use of mass spectrometers in the ICU.

Carbon Dioxide↗
PubMed1996

Evaluation of effect of lung resection on lobar ventilation and perfusion using intrabronchial capnography.

Intrabronchial capnography was applied in 11 lung cancer patients to investigate the effects of lobectomy on regional lung function. Spirometry and intrabronchial capnography were performed before surgery (PRE), and during the early (POST1,19 +/- 5 POD) and late (POST2, 184 +/- 98 POD) postoperative periods. End-tidal carbon dioxide concentration (EtCO2) and Smidt's velocity profile index (V-index) were calculated from each lobar capnogram obtained bronchoscopically. The V-index of lobes without cancer on the operated-on side increased after surgery (PRE, 10.7 +/- 5.0%; POST1, 14.3 +/- 9.4%, NS; POST2, 16.8 +/- 8.6%, p < 0.05), while the V-index on the unoperated-on side decreased after surgery (PRE, 10.5 +/- 5.3%; POST1, 7.9 +/- 3.5%, p < 0.05; POST2, 7.2 +/- 2.9%, p < 0.05). EtCO2 after surgery was lower on the operated-on side (POST1, 5.1 +/- 1.1%; POST2, 4.6 +/- 1.1%) than on the unoperated-on side (POST1, 5.4 +/- 0.9%, p < 0.05; POST2, 5.0 +/- 0.9%, p < 0.01). Since the V-index and EtCO2 are compatible with the expiratory flow rate and the perfusion/ventilation ratio, respectively, we concluded that the air flow decreased on the operated-on side and increased on the unoperated-on side postoperatively and that perfusion on the operated-on side was more severely reduced than ventilation. These findings suggest that intrabronchial capnography is useful for assessing the ventilation and perfusion of the individual lobes as single units.

Aged↗
PubMed1983

Capnography facilitates blind nasotracheal intubation.

Continuous capnography recordings were made during blind nasotracheal intubation of 17 patients breathing spontaneously. The carbon dioxide analyzer (CD 300, Datex Helsinki) was connected to the open proximal end of the endotracheal tube. In addition to the auscultatory findings, capnography gave valuable information about the position of the endotracheal tube during the entire intubation procedure. The low and peaked CO2 waves recorded from the nasopharynx tended to become higher and more flat-topped as the larynx was approached. When the tip of the endotracheal tube erroneously glided behind the larynx (12 of the 17 cases) this was promptly revealed by absence of CO2 in the recording. On the other hand, entrance of the tube into the trachea could always be rapidly detected as typical flat-topped CO2 waves were seen in the capnogram. Thus capnography facilitates orientation during blind nasotracheal intubation and rapidly detects accidental oesophageal intubation. The capnographic recording also is a valuable and reliable additional sign and document of correct endotracheal intubation.

Auscultation↗
PubMed1993

[Capnography. A new monitoring method may improve patient safety during anesthesia and in the recovery room].

This review describes the diagnostic possibilities of capnography: the graphic presentation of carbon dioxide concentrations in respiratory gas during the entire respiratory cyclus. The monitoring may confirm that the tube used for intubating the patient's trachea is positioned in the patient's airway, and indicates dysfunction of the tube or of the ventilator. Capnography can also rapidly provide important information about a patient's ventilation, circulation and metabolism. This may improve patient safety during anaesthesia and in the intensive care unit. Patients without artificial airways may also be monitored by capnography. The method may reduce the number of arterial blood gases required to check the degree of ventilation.

Anesthesia, General↗
PubMed1988

Oxygenator exhaust capnography: an in vitro evaluation.

The aim of the study was to examine whether oxygenator exhaust capnography could be used to monitor blood carbon dioxide tension in an in vitro cardiopulmonary bypass model. Carbon dioxide tension in the oxygenator's exhaust gas was measured by a capnograph and compared with that in the blood measured by blood gas analysis. Also investigated was the relationship between the capnograph's measurements and blood pH. The effects of gas and blood flow, temperature, and pH on the measurements were examined. A good correlation was found between PCO2 measured by the capnograph and by the blood gas analyzer (r = 0.997, P < 0.001). When the capnograph's results were corrected for 95% oxygen, the accuracy improved further. There was a significant correlation between oxygenator exhaust PCO2 and temperature (rs = 0.843, P < 0.05), but the difference in PCO, was small in the range examined. No significant correlation was found between oxygenator exhaust PCO2 and blood or gas flow. A reasonable correlation between blood pH and oxygenator exhaust PCO2 (r = 0.965, P < 0.001) was found, but the metabolic component of pH could be altered without correlation with exhaust PCO2 (rs = 0.203). In conclusion, oxygenator exhaust capnography was used with reasonable accuracy and reliability to monitor blood PCO2 in an in vitro cardiopulmonary bypass model.

Blood Gas Analysis↗
PubMed2007

Capnography for procedural sedation and analgesia in the emergency department.

Although it is standard of care for patient safety monitoring in anesthesia, capnography is not routinely used for emergency department procedural sedation and analgesia. We discuss the use of capnography as a diagnostic monitoring modality for procedural sedation and analgesia, focusing on the physiology and interpretation of the CO2 waveform and recognition of normal, abnormal, and drug-induced ventilatory patterns.

Analgesia↗
PubMed1998

Utility of monitoring capnography, pulse oximetry, and vital signs in the detection of airway mishaps: a hyperoxemic animal model.

This study was undertaken to determine the time interval for changes in end-tidal CO2, oxygen saturation (SaO2), heart rate (HR), and blood pressure (BP) in response to an acute airway obstruction or hypopharyngeal extubation in a hyperoxemic model. Complete and partial airway obstructions were simulated with complete and partial cross-clamping of an endotracheal (ET) tube in five anesthetized, nonparalyzed, mechanically ventilated Yorkshire minipigs with initial PAo2 of > 400 mm Hg. Placement of the ET tube into the hypopharynx was performed to simulate accidental extubation. Both sidestream (SS) and mainstream (MS) capnography were used. Continuous pulse oximetry monitored SaO2, femoral arterial catheter monitored systolic BP, and electrocardiograph monitored HR. The time intervals for the capnograph wave to flatten and for the monitor to display zero were recorded after each airway alteration. The time interval to a change in the initial HR of 10 beats/min, a change of initial systolic BP of 10 mm Hg, and a change of initial SaO2 of 5% were recorded. Experiments were carried out for 180 seconds, and 25 trials were performed. HR, systolic BP, and SaO2 did not change for the 180-second duration of the trials. Complete obstruction produced a flattening of the SS and MS waveform in 8 +/- 2 seconds and 6 +/- 2 seconds, respectively. The SS and MS monitors displayed zero in 19 +/- 1 seconds and 68 +/- 7 seconds, respectively. Partial obstruction did not produce flattening of the wave or a monitor displaying zero. Hypopharyngeal extubation produced a flattening of the SS and MS waveform in 7 +/- 1 seconds and 7 +/- 2 seconds, respectively. The SS and MS monitors displayed zero in 18 +/- 3 seconds and 76 +/- 16 seconds, respectively. Continuous end-tidal CO2 capnography detects acute airway obstruction and hypopharyngeal extubation more rapidly than does pulse oximetry or vital sign monitoring in a hyperoxemic porcine model.

Airway Obstruction↗
PubMed1999

Volumetric capnography in patients with acute lung injury: effects of positive end-expiratory pressure.

The aim of the study was to analyse the effects of positive end-expiratory pressure (PEEP) on volumetric capnography and respiratory system mechanics in mechanically ventilated patients. Eight normal subjects (control group), nine patients with moderate acute lung injury (ALI group) and eight patients with acute respiratory distress syndrome (ARDS group) were studied. Respiratory system mechanics, alveolar ejection volume as a fraction of tidal volume (VAE/VT), phase III slopes of expired CO2 beyond VAE and Bohr's dead space (VD/VT(Bohr)) at different levels of PEEP were measured. No differences in respiratory system resistances were found between the ALI and ARDS groups. VD/VT(Bohr) and expired CO2 slope beyond VAE were higher in ALI patients (0.52+/-0.01 and 13.9+/-0.7 mmHg x L(-1), respectively) compared with control patients (0.46+/-0.01 and 7.7+/-0.4 mmHg x L(-1), p<0.01, respectively) and in ARDS patients (0.61+/-0.02 and 24.9+/-1.6 mmHg x L(-1), p<0.01, respectively) compared with ALI patients. VAE/VT differed similarly (0.6+/-0.01 in control group, 0.43+/-0.01 in ALI group and 0.31+/-0.01 in ARDS group, p<0.01). PEEP had no effect on VAE/VT, expired CO2 slope beyond VAE and VD/VT(Bohr) in any group. A significant correlation (p<0.01) was found between VAE/VT and expired CO2 slope beyond VAE and lung injury score at zero PEEP. Indices of volumetric capnography are affected by the severity of the lung injury, but are unmodified by the application of positive end-expiratory pressure.

Adult↗
PubMedDate not supplied

Use of capnography in the delivery room for assessment of endotracheal tube placement.

OBJECTIVE: Determine whether end-tidal CO(2) (ETCO(2)) monitoring allows for more rapid discrimination of tracheal versus esophageal intubation than standard clinical assessment during neonatal resuscitation in the delivery room. STUDY DESIGN: Endotracheal tube (ETT) placement was assessed using either a hand-held monitor that displayed graphic and quantitative ETCO(2) by an investigator not involved in the resuscitation, or using clinical parameters by the resuscitation team unaware of the ETCO(2) data. The time differences between ETCO(2) and clinical determinations of ETT placement were compared. RESULTS: Capnography correctly identified all 16 tracheal and 11 esophageal intubations performed on 16 study infants. The median times (and range) in seconds required for capnographic and clinical determination of tracheal intubation were 9 (4 to 26) vs. 35 (18 to 70), p<.001, and for esophageal intubation were 9 (4 to 17) vs. 30 (25 to 111), p=.001. CONCLUSION: Capnography allowed more rapid determination of both tracheal and unintended esophageal intubation than clinical assessment.

Apgar Score↗
PubMedDate not supplied

Accuracy of a new low-flow sidestream capnography technology in newborns: a pilot study.

OBJECTIVE: To evaluate the accuracy of a new low-flow sidestream capnography technology and analyze components of the capnogram in mechanically ventilated newborns with and without pulmonary disease. METHODS: Twenty patients were prospectively identified. Eligible infants were mechanically ventilated and had an indwelling arterial catheter. Two groups were identified: newborns who were receiving mechanical ventilation for pulmonary diseases, and newborns who were receiving postoperative mechanical ventilation for nonpulmonary conditions. End-tidal CO(2) (PetCO(2)) was measured for 1-minute pre- and post-arterial blood sampling, and PetCO(2) and PaCO(2) were compared for each patient. Eight quantitative waveform parameters were also measured on all patients. RESULTS: Newborns in the pulmonary group (n=13) (persistent pulmonary hypertension of the newborn/meconium aspiration syndrome, respiratory distress syndrome, pneumonia) and newborns in the control group (n=7) were matched for birth weight, gestational age, and postnatal age. PetCO(2)-PaCO2 Gradient values were higher in the pulmonary group (7.4+/-3.3 mm Hg) than controls (3.4+/-2.4 mm Hg). Four waveform parameters (ascending slope, alveolar angle, alpha angle, descending angle) were identified, which independently differentiated patients with pulmonary disease from controls. CONCLUSIONS: Low-flow capnography with Microstream technology accurately measured alveolar CO(2) in newborns without pulmonary disease, as demonstrated by normal PetCO(2)-PaCO(2) gradients. The measured PetCO(2)-PaCO(2) gradient, as expected, was significantly higher in newborns with pulmonary disease. We also identified four quantitative waveform parameters that may be useful in differentiating between mechanically ventilated newborn patients with and without lung disease.

Capnography↗
PubMed2001

Hemodynamic applications of capnography.

The measurement of the pressure of exhaled carbon dioxide (PetCO2) via capnography has several useful hemodynamic applications. This article discusses integrating PetCO2 values with hemodynamic assessment. Capnography can be applied to hemodynamic assessment in three key ways: (1) identification of end-expiration during pulmonary artery and central venous pressure measurements, (2) assessment of pulmonary perfusion and alveolar deadspace, (3) assessment of cardiopulmonary resuscitative efforts. The article presents research, sample waveforms for end-expiration identification, and case examples.

Adult↗
PubMed2005

Volumetric capnography: reliability and reproducibility in spontaneously breathing patients.

Volumetric capnography provides a breath-by-breath analysis of ventilation-perfusion imbalances and deadspace volumes. The technique has been best described in intubated and ventilated patients, but promising clinical applications also concern spontaneously breathing patients. The objective of the study was to verify the reliability and reproducibility of a new capnographic program in various types of clinical conditions. In a first step, 56 patients, either healthy or with acute respiratory disorders, were connected to a sidestream gas sampler and flow sensor through a mouthpiece. An acquisition software synchronized expired CO2 and flow data to create volumetric capnographic curves. Mixed expired CO2 partial pressure, corresponding to the exhaled CO2 of the effective tidal volume, was simultaneously collected in a neoprene bag for comparison. In a second step, changes in airway deadspace before and after the adjunction of known spacer volumes were compared in six healthy volunteers. The mean difference between both methods in measuring mixed expired CO2 partial pressure was -0.9 mmHg (SE 0.2 mmHg, P<0.001). The limits of agreement extended from -4.4 to 2.5 mmHg. The interobserver correlation coefficient for reproducibility was 0.98. Airway deadspace volume, after correction for extra volumes, was not statistically different than the basic value (P=0.89). In conclusion, volumetric capnography can be compared with references when used in spontaneously breathing patients. Future developments and clinical applications should clarify its role as a non-invasive method for deadspace and ventilation-perfusion imbalances analysis.

Adult↗
PubMed1997

Capnography for monitoring non-intubated spontaneously breathing patients in an emergency room setting.

OBJECTIVE: To examine the feasibility of using expiratory capnography as an indicator of airway obstruction in non-intubated resuscitation room patients. METHODS: Patients with potential respiratory compromise admitted to the resuscitation room were assessed for widespread expiratory wheeze. This was taken as clinical evidence of airways obstruction. Expiratory capnograms of these patients and patients who had no wheeze were obtained. The traces were analysed for basic morphology and where appropriate the slope ratio (SR) between phase 1 (S1) and phase 2 (S2) of the trace was obtained. RESULTS: Thirty eight patients with a variety of clinical conditions causing potential or actual respiratory impairment were studied. All patients tolerated the nasal capnogram cannulae. Twelve had no clinical evidence of airway obstruction and all had capnograms with normal morphology. Eleven of these were analysed further. The mean value for SR was 7.57 (SEM 0.18), 95% confidence interval 6.37 to 8.77. Twenty six patients had clinical evidence of airway obstruction "sharks fin" morphology. Fourteen of these were analysed to determine SR. The mean value was 31.9 (4.46), 95% CI 22.9 to 40.8. There was a significant difference in the mean value for SR between the two groups (P << 0.001). CONCLUSIONS: Capnography may be used as a means of continuous respiratory monitoring in non-intubated acutely ill patients. Capnogram analysis may be used to indicate airway obstruction in these patients. Further work is required to correlate curve indices to degree of airway obstruction.

Adolescent↗