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At least 19 recordsLinked to original sources

PubMed1995

[Non-invasive patient monitoring in veterinary medicine: pulse oximetry and capnography. II. Capnography].

Capnography measures carbon dioxide concentration or partial pressure of the respiratory gas continuously and non-invasively. The endtidal value is of great diagnostic value, it corresponds approximately to the arterial value, except for ventilation-perfusion-mismatching (horse), shunting (horse), or increased dead-space-ventilation (panting in the dog). Capnography primarily serves for monitoring of spontaneous and artificial ventilation, it is a reliable method for detecting hypo- and hyperventilation. Because metabolism and circulation influence the amount of carbon dioxide eliminated in the lung, capnography monitors these functions too. The plotting of the carbon dioxide concentration as a carbon dioxide-time-diagram draws attention to malfunctions of the equipment. Technical problems of capnography depend on the design of the capnograph (main- or side-stream) used as well as on the weight of the patient. In the discussion the value of pulse oximetry and capnography in detection of critical events during anaesthesia is compared. Capnography is superior to pulse oximetry in the capability to detect critical events. But pulse oximetry complements capnography perfectly, both methods together give a good impression of the patient's state of health.

Animals↗

PubMed1995

The use of capnography for recognition of esophageal intubation in the neonatal intensive care unit.

Failure to recognize esophageal intubation can result in severe hypoxia and permanent neurologic injury. Capnography is a standard monitoring modality in the operating room but has not been utilized fully in other environments. We used capnography at the time of endotracheal intubation in the neonatal intensive care unit (NICU) to determine whether capnography could more quickly and accurately identify endotracheal tube position than other clinical indicators of endotracheal tube position. One hundred intubation episodes were studied in 55 neonates. Capnograms were obtained 15 and 120 sec following tube placement. Intubating personnel were blinded to the capnographic data and determined endotracheal tube location (trachea vs. esophagus) by clinical criteria only. The sensitivity and specificity of capnography and clinical examination for identification of tube position were analyzed, and the time required for establishing by clinical confirmation whether the tube was in the trachea or not was compared to that required for capnography. Forty of 100 intubation attempts resulted in esophageal intubation. Capnography correctly identified these errant tube placements in 39 of 40 instances and did so in 1.6 sec (SD +/- 2.4). Capnography failed to identify successful endotracheal intubation on only one occasion. Clinical indicators of tube position required 97.1 sec (SD +/- 92.6) to identify an esophageal intubation and failed to identify successful endotracheal intubation in 5 of 60 cases. We conclude that capnography is a valuable adjunct to clinical examination to demonstrate whether an endotracheal tube is placed correctly in the trachea of neonates in the NICU.

Blood Gas Monitoring, Transcutaneous↗

PubMedDate not supplied

Initiation of capnography in a rural EMS system.

OBJECTIVE: Capnography is an effective means of monitoring cardiopulmonary resuscitation and managing endotracheal intubation. Numerous studies have validated its use in urban settings, but none have described its integration into a rural EMS system. The authors describe the process of integrating capnography training and use in Jackson County, West Virginia. METHODS: Two CO2SMOS capnography/ pulse oximeters were placed on the lead ambulances in Jackson County, West Virginia. Training in the operation and application of the equipment was provided, and providers used the monitors for a period of six months. A questionnaire was administered to assess their understanding of the equipment and its utility in prehospital care. Results were compiled and summarized. RESULTS: Ninety percent of the EMS providers subjectively felt that they understood capnography and its clinical application. They answered questions designed to test their understanding with 65% accuracy. CONCLUSION: In this model, capnography was successfully integrated into a rural EMS system. Reasonable proficiency in the use of the CO2SMOS monitor and an understanding of the information obtained were demonstrated, although the EMS providers tended to overestimate their actual understanding of the clinical application of capnography. This supports the need for ongoing, targeted education. The authors feel that capnography provides information that is uniquely relevant in rural EMS systems.

Allied Health Personnel↗

PubMed1991

Use of capnography in critically ill adults.

A major responsibility of the critical care practitioner is to assure adequate ventilation of the critically ill patient. The traditionally used methods for evaluating ventilation, such as physical examination and measurement of vital signs, are indirect. The most commonly used direct method, measurement of arterial carbon dioxide tension, is invasive and intermittent. Capnography provides the critical care practitioner with a continuous, noninvasive, and accurate assessment of ventilation. To interpret capnographic data, the practitioner must have a clear understanding of normal and abnormal patterns of carbon dioxide elimination in the lung. We review relevant respiratory physiology as a basis for understanding the value of capnography. The technology on which capnography is based is described with emphasis on methods of gas sampling, limitations of capnography, and features available on currently marketed instruments. Representative capnograms are presented and the data interpreted to enable the practitioner to determine when capnography is an appropriate monitor for the critically ill adult.

Carbon Dioxide↗

PubMed1998

Influence of pulse oximetry and capnography on time to diagnosis of critical incidents in anesthesia: a pilot study using a full-scale patient simulator.

OBJECTIVE: Many studies (outcome, epidemiological) have tested the hypothesis that pulse oximetry and capnography affect the outcome of anesthetic care. Uncontrollable variables in clinical studies make it difficult to generate statistically conclusive data. In the present study, we eliminated the variability among patients and operative procedures by using a full-scale patient simulator. We tested the hypothesis that pulse oximetry and capnography shorten the time to diagnosis of critical incidents. METHODS: A simulator was programmed to represent a patient undergoing medullary nailing of a fractured femur under general anesthesia and suffering either malignant hyperthermia, a pneumothorax, a pulmonary embolism or an anoxic oxygen supply. One hundred thirteen anesthesiologists were randomly assigned to one of two groups of equal size, one with access to pulse oximetry and capnography data and the other without. Each anesthesiologist was further randomized to one of the four critical incidents. Each anesthetic procedure was videotaped. The time to correct diagnosis was measured and analyzed. RESULTS: Based on analysis of 91 of the subjects, time to diagnosis was significantly shorter (median of 432 s vs. >480 s) for the anoxic oxygen supply scenario (p = 0.019) with pulse oximetry and capnography than without. No statistical difference in time to diagnosis was obtained between groups for the other three critical incidents. CONCLUSIONS: Simulation may offer new approaches to the study of monitoring technology. However, the limitations of current simulators and the resources required to perform simulator-based research are impediments to wide-spread use of this tool.

Anesthesia, General↗

PubMed1998

Aspirated air capnography with esophageal detector device to confirm tracheal intubation in rapid sequence induction.

Verification of the proper placement of a tracheal tube by capnography in rapid sequence induction can lead to aspiration if the patient is ventilated with the tube in the esophagus. In this study we have associated the capnography with the esophageal detector device as modified by Nunn. In 49 patients, two endotracheal tubes were introduced, one in the esophagus and the other in the trachea. An anesthesiologist, unaware of which tube is in the trachea, squeezed the bulb of the esophageal detector device, attached it to the sidestream of the capnography and the endotracheal tubes, then released it. No reinflation of the bulb was seen with the esophageal tube. Two types of reinflation were seen with the tracheal tube: slow (6 cases), all were obese, and instant (43 cases) in the remaining patients. The air aspirated from the respiratory tract by the bulb was analyzed by the capnograph; CO2 was detected from all the tracheal tubes but not from the esophageal ones. We concluded that the esophageal detector device and capnography used as described in our study is a simple reliable test to confirm the proper placement of a tracheal tube before starting ventilation in rapid sequence induction.

Adolescent↗

PubMed1995

Terminology and the current limitations of time capnography: a brief review.

The carbon dioxide (CO2) trace versus time (time capnography) is convenient and adequate for clinical use. This is the method most commonly utilized in capnography. However, the current terminology in time capnography has not yet been standardized and is, therefore, a potential source of confusion. Standard terminology that is based on convention and logic to represent the various phases of a time capnogram is essential. The time capnogram should be considered as two segments: an inspiratory segment and an expiratory segment. The inspiratory segment is termed as phase ); the expiratory segment is divided into phases I, II, III, and, occasionally, IV. Phase I represents the CO2-free gas from the airways (anatomical dead space); phase II consists of a rapid S-shaped upswing on the tracing due to mixing of dead space gas with alveolar gas; and phase III, the alveolar plateau, represents CO2-rich gas from the alveoli. The physiologic basis of phase IV, the terminal upswing at the end of phase III, which is observed in capnograms recorded under certain circumstances (such as in pregnant subjects and obese subjects) is discussed in detail. The clinical implications of the alpha angle, which is the angle between phases II and III, and the beta angle, which is the angle between phases III and the descending limb of phase 0, are outlined. The subtle but important limitations of time capnography are reviewed; its current status as well as its future potential are explored.

Carbon Dioxide↗

PubMed1994

Control of carbon dioxide levels during neuroanaesthesia: current practice and an appraisal of our reliance upon capnography.

With the widespread availability of capnography, many anaesthetists have swung away from formally verifying hypocapnia by intraoperative arterial blood gas analysis and, instead, have come to rely upon capnography as an acceptable and constant predictor of arterial CO2 tension (PaCO2) during neurosurgery. However, the nature of the arterial-end-tidal CO2 gradient is complex, and is frequently unexpectedly large, or even negative. The importance of close intraoperative CO2 control during neurosurgery--more specifically, routine hyperventilation, and our reliance upon capnography to guide intraoperative management--is reappraised. There is a growing appreciation of the adverse effects of hyperventilation and hypocarbia, especially upon abnormal or ischaemic brain, and it is clear that capnography alone cannot be used to confidently predict the true PaCO2 during neuroanaesthesia.

Anesthesia, General↗

PubMed1989

An investigation of capnography and pulse oximetry as monitors of pediatric patients sedated for dental treatment.

Traditional methods of monitoring sedated pediatric dental patients have major shortcomings. This study evaluated the use of capnography in conjunction with pulse oximetry for monitoring children during conscious sedation for dental treatment. The specific purposes of the study were to determine if capnography would: (1) detect ventilatory changes that subsequently cause an oxyhemoglobin desaturation as detected by pulse oximetry; and (2) detect an airway obstruction. Ten pediatric dental patients (mean age 2 years, 10 months) were sedated with 75 mg/kg of chloral hydrate in strict accordance with the Guidelines for the Elective Use of Conscious Sedation, Deep Sedation, and General Anesthesia in Pediatric Patients of the American Academy of Pediatric Dentistry and the American Academy of Pediatrics (1985). All patients were monitored continuously using both capnography and pulse oximetry. Analysis of data obtained using these monitors revealed that specific end-tidal CO2 values were not predictive for subsequent oxyhemoglobin desaturations and that capnography was very accurate in detecting complete obstruction of the airway. Pulse oximetry revealed that all patients had mild oxyhemoglobin desaturations and that 50% had moderate desaturations.

Anesthesia, Dental↗

PubMed1997

Capnography and ventilatory assessment during ambulatory dentoalveolar surgery.

PURPOSE: The purpose of this study was to determine whether capnography is a more sensitive monitor than auscultation of breath sounds in detecting ventilatory changes consistent with hypoventilation, obstruction, or apnea and in detecting ventilatory changes that can be associated with oxygen desaturation. PATIENTS AND METHODS: Fifty-five patients received intravenous agents and supplemental oxygen to achieve a state of deep sedation or general anesthesia for removal of impacted third molars. The surgeon/anesthetist monitored respiratory status using a pretracheal stethoscope and direct observation. A blinded observer with no access to the patient or anesthetist monitored respiratory status using capnography. A second observer monitored all respiratory parameters to allow for correlation between clinical and electronic monitors. RESULTS: Ventilatory status was continuously represented by capnogaphy. The Pearson correlation coefficient showed a positive correlation between increased end-tidal CO2 (PETCO2) and decreased oxygen saturation that became stronger with greater positive changes in PETCO2. An additive relationship was found between PETCO2 and respiratory rate (RR), with increased PETCO2 and decreased RR contributing to decreased oxygen saturation. CONCLUSION: Patients with nasal ventilatory exchange maintain this exchange throughout the anesthesia so that sampling of nasal PETCO2 is an effective way to monitor ventilatory status. Respiratory depression or obstructive ventilatory changes detected by capnography showed a high sensitivity and low positive predictive value in detecting oxygen desaturation. The current technology does not show a clinically satisfactory correlation between PETCO2 and oxygen saturation. However, a combined increase in PETCO2 and decrease in RR suggested a trend of decreasing oxygen saturation.

Adolescent↗

PubMed1999

Capnography. A key underutilized technology.

Based on the multiple applications and the potential cost savings, every ICU should have enough capnography for all intubations and probably for all mechanically ventilated patients. Of the multiple clinical applications of capnography, most attention should be focused on its use with intubation and resuscitation. Other applications, such as blood gas and ventilation-perfusion scan reduction, should be instituted after the primary areas have been implemented. While capnography modules may appear to be expensive at first glance, an analysis of their clinical application reveals they can save the hospital hundreds of thousands of dollars beyond the purchase price.

Aged↗

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↗