[Clinical evaluation of a minirespirator by capnography].
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Anesthesia↗
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Capnography during anesthesia and intensive care.
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Adult↗
Capnography and cuff inflation to aid blind tracheal intubation.
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Acute Disease↗
Evaluation of residual vascularisation in oesophageal substitution gastroplasty by surface oximetry-capnography and photoplethysmography. An experimental study.
OBJECTIVE: To evaluate residual vascularisation in gastroplasty and its possible relation to the development of anastomotic fistulas or dehiscences after oesophageal resection. DESIGN: Experimental open study. MATERIAL: Eleven mongrel dogs. INTERVENTIONS: Gastric parietal blood flow was evaluated by photoplethysmography and measurement of surface oxygen and carbon dioxide tensions under basal conditions and after Akiyama's tubular gastroplasty. Temperature, heart rate, and electrocardiogram; arterial pressure, pulmonary arterial pressure, pulmonary capillary pressure, central venous pressure, cardiac output, venous oxygen saturation, and arterial blood gas tensions were monitored under stable haemodynamic conditions. RESULTS: After gastroplasty, the mean serosal oxygen tension (pO2) of 8.6 mmHg and carbon dioxide tension (pCO2) of 99.5 mmHg and residual photoplethysmographic wave amplitude (8%) indicated considerable severe ischaemia at the fundus. There was relative ischaemia of the mid-stomach with residual mean values of 52.7 mmHg, 77.8 mmHg, and 57% for pO2; pCO2 and PPG wave amplitude, respectively. CONCLUSIONS: Important devascularisation of the fundus, theoretically incompatible with healing, occurs after gastroplasty. Operative photoplethysmography and surface measurements of pO2 and pCO2 are good ways of evaluating the level and degree of ischaemia in gastric tubes for oesophageal replacement.
Anastomosis, Surgical↗
[Study of external respiratory efficiency indices determined by a method of capnography in late pregancy toxicoses].
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Blood Gas Analysis↗
[Capnography in the detection of partial extubation].
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Adult↗
Automated graphic assessment of respiratory activity is superior to pulse oximetry and visual assessment for the detection of early respiratory depression during therapeutic upper endoscopy.
BACKGROUND: Recommendations from the American Society of Anesthesiologists suggest that monitoring for apnea using the detection of exhaled carbon dioxide (capnography) is a useful adjunct in the assessment of ventilatory status of patients undergoing sedation and analgesia. There are no data on the utility of capnography in GI endoscopy, nor is the frequency of abnormal ventilatory activity during endoscopy known. The aims of this study were to determine the following: (1) the frequency of abnormal ventilatory activity during therapeutic upper endoscopy, (2) the sensitivity of observation and pulse oximetry in the detection of apnea or disordered respiration, and (3) whether capnography provides an improvement over accepted monitoring techniques. METHODS: Forty-nine patients undergoing therapeutic upper endoscopy were monitored with standard methods including pulse oximetry, automated blood pressure measurement, and visual assessment. In addition, graphic assessment of respiratory activity with sidestream capnography was performed in all patients. Endoscopy personnel were blinded to capnography data. Episodes of apnea or disordered respiration detected by capnography were documented and compared with the occurrence of hypoxemia, hypercapnea, hypotension, and the recognition of abnormal respiratory activity by endoscopy personnel. RESULTS: Comparison of simultaneous respiratory rate measurements obtained by capnography and by auscultation with a pretracheal stethoscope verified that capnography was an excellent indicator of respiratory rate when compared with the reference standard (auscultation) (r = 0.967, p < 0.001). Fifty-four episodes of apnea or disordered respiration occurred in 28 patients (mean duration 70.8 seconds). Only 50% of apnea or disordered respiration episodes were eventually detected by pulse oximetry. None were detected by visual assessment (p < 0.0010). CONCLUSIONS: Apnea/disordered respiration occurs commonly during therapeutic upper endoscopy and frequently precedes the development of hypoxemia. Potentially important abnormalities in respiratory activity are undetected with pulse oximetry and visual assessment.
Adult↗
Capnometry in the spontaneously breathing patient.
PURPOSE OF REVIEW: Capnography has been used in the operating room by anesthesiologists for over a decade. Along with pulse oximetry, it has reduced anesthesia-related morbidity and mortality. Traditionally, capnography has been used to confirm the placement of the endotracheal tube. This review looks into the literature for an update on the use of capnography in the spontaneously breathing patient. RECENT FINDINGS: Several studies support the additional safety afforded by the use of capnography in patients undergoing sedation for procedures in various situations outside the operating room. Capnography has been used as an aid in the diagnosis of pulmonary embolism and sleep-related disorders, as a continuous monitor of metabolic status of pediatric patients with diabetic ketoacidosis and, along with pulse oximetry, in lung-function laboratories to estimate blood gases. SUMMARY: Capnography has become a mandatory or recommended monitoring tool in the practice of anesthesiology. It is making inroads into other medical specialties as a monitoring and diagnostic tool. The use of this technology by non-anesthesiologists will continue to increase. In the opinion of the authors capnography should be used in all cases requiring sedation either in or out of the operating room.
Journal Article↗
Comparison of three different methods to confirm tracheal tube placement in emergency intubation.
OBJECTIVES: Verification of endotracheal tube placement is of vital importance, since unrecognized esophageal intubation can be rapidly fatal (death, brain damage). The aim of our study was to compare three different methods for immediate confirmation of tube placement: auscultation, capnometry and capnography in emergency conditions in the prehospital setting. DESIGN AND SETTING: Prospective study in the prehospital setting. PATIENTS AND INTERVENTIONS: All adult patients (>18 years) were intubated by an emergency physician in the field. Tube position was initially evaluated by auscultation. Then, capnometry was performed with infrared capnometry and capnography with infrared capnography. The examiners looked for the characteristic CO(2) waveform and value of end-tidal carbon dioxide (EtCO(2)) in millimeters of mercury. Determination of final tube placement was performed by a second direct visualization with laryngoscope. Data are mean +/- SD and percentages. MEASUREMENTS AND RESULTS: Over a 4year period, 345 patients requiring emergency intubation were included. Indications for intubation included cardiac arrest ( n=246; 71%) and non-arrest conditions ( n=99; 29%). In nine (2.7%) patients, esophageal tube placement occurred. The esophageal intubations were followed by successful endotracheal intubations without complications. The capnometry (sensitivity and specificity 100%) and capnography (sensitivity and specificity 100%) were better than auscultation (sensitivity 94% and specificity 83%) in confirming endotracheal tube placement in non-arrest patients ( p<0.05). Capnometry was highly specific (100%) but not sensitive (88%) for correct endotracheal intubation in patients with cardiopulmonary arrest (capnometry versus auscultation and capnometry versus capnography, p<0.05). CONCLUSION: Capnography is the most reliable method to confirm endotracheal tube placement in emergency conditions in the prehospital setting.
Auscultation↗
Clinical probability and alveolar dead space measurement for suspected pulmonary embolism in patients with an abnormal D-dimer test result.
BACKGROUND: Most patients with suspected pulmonary embolism (PE) have a positive D-dimer test and undergo diagnostic imaging. Additional non-invasive bedside tests are required to reduce the need for further diagnostic tests. OBJECTIVES: We aimed to determine whether a combination of clinical probability assessment and alveolar dead space fraction measurement can confirm or exclude PE in patients with an abnormal D-dimer test. METHODS: We assessed clinical probability of PE and alveolar dead space fraction in 270 consecutive in- and outpatients with suspected PE and positive D-dimer. An alveolar dead space fraction < 0.15 was considered normal. PE was subsequently excluded or confirmed by venous compression ultrasonography, spiral computed tomography and a 3-month follow-up. Radiologists were unaware of the results of clinical probability and capnography. RESULTS: PE was confirmed in 108 patients (40%). Capnography had a sensitivity of 68.5% (95% confidence interval [CI]: 58.9-77.1%) and a specificity of 81.5% (95% CI: 74.6-87.1%) for PE. Forty-five patients (16.6%) had both a low clinical probability and normal capnography (sensitivity: 99.1%, 95% CI: 94.9-100%) and 34 patients (12.6%) had both a high clinical probability and abnormal capnography (specificity: 100%, 95% CI: 97.7-100%). CONCLUSION: Capnography alone does not exclude PE accurately. The combination of clinical probability and capnography accurately excludes or confirms PE and avoids further testing in up to 30% of patients.
Capnography↗
The esophageal detector device. Does it work?
BACKGROUND: The esophageal detector device (EDD) is a diagnostic tool for confirmation of tracheal intubation. Capnography is the accepted standard for such confirmation. The purpose of this investigation was to determine whether results using the EDD and capnography agree. METHODS: Five hundred patients were divided into three separate studies. In study 1, with 300 consecutive patients, tracheal intubation was performed and tested with the EDD followed by capnography. In study 2, 100 patients had the esophagus intentionally intubated, and confirmation was tested similarly. The tube was then removed and the trachea intubated, and testing followed. Study 3 involved 100 patients and used a double-blind, randomized design. The tube was intentionally inserted into either the esophagus (n = 5) or trachea (n = 49), and testing followed. RESULTS: In study 1, the compressed EDD bulb reinflated 270 times and always agreed with capnography; in 20 of the 270 subjects (7%) bulb reinflation was delayed, taking from 5-30 s. In 30 instances, the bulb remained compressed, and there was no capnogram indicating esophageal intubation. In study 2, regardless of esophageal or tracheal intubation, agreement between EDD and capnogram was 100%. In study 3, the agreement between the two detecting instruments was 100%, but reinflation of the EDD bulb was delayed in 4% of tracheal intubations. In the 500 patients studied, results from the EDD and capnogram always agreed, but in 6% of all tracheal intubations, the EDD bulb inflated slowly. Of 181 esophageal intubations, the results from the EDD and capnogram always agreed, i.e., there was no reinflation or capnogram. The sensitivity, specificity, and predictive value for the EDD in all of these studies was 100%. CONCLUSIONS: The EDD is a valuable diagnostic technique for confirming tracheal intubation. Results using EDD agree with results using capnography; in 6% of instances there is a slow reinflation; and where there is no capnography, such as on hospital wards, EDD may be a useful diagnostic tool.
Double-Blind Method↗
Colorimetric end-tidal carbon dioxide monitoring for tracheal intubation.
We evaluated a colorimetric end-tidal carbon dioxide (ETCO2) detector (FEF end-tidal carbon dioxide detector, Fenem, New York, N.Y.) during 62 intubations in anesthetized patients who were hemodynamically stable. The intubations were performed during a drill that simulates difficult tracheal intubation and therefore is associated with an increased risk of esophageal intubation. Each intubation attempt was monitored by two anesthesiologists and a research assistant who together used chest auscultation, colorimetric ETCO2, and capnography to confirm tracheal intubation and detect esophageal intubation. The reliability of the monitors was compared with capnography. Colorimetric ETCO2 confirmed tracheal intubations and detected esophageal intubations 100% of the time, as judged by capnography. There were no false-positive or false-negative decisions based on endotracheal tube position; however, one equivocal color change occurred, which was caused by failure to inflate the endotracheal tube cuff. Colorimetric ETCO2 monitoring confirmed tracheal intubation more rapidly than did chest auscultation (P less than 0.001) or capnography (P less than 0.05), and detected esophageal intubation more rapidly than did chest auscultation (P less than 0.05) and as rapidly as capnography did. Confirmation of tracheal intubation was achieved earlier than detection of esophageal intubation with all three monitors (P less than 0.05). We conclude that colorimetric ETCO2 monitoring is a safe, reliable, rapid, simple, and portable method for determining endotracheal tube position for patients who are hemodynamically stable and should be recommended where capnography is not available.
Carbon Dioxide↗
Capnographic monitoring of ventilatory status during moderate (conscious) sedation.
BACKGROUND: Moderate (conscious) sedation is required to perform endoscopic procedures. Capnography provides a means for continuous, real-time monitoring of ventilation and may also decrease the incidence of oversedation. METHODS: A retrospective examination of all endoscopic procedures performed from January through December 2001 at our institution was undertaken to determine the potential benefits of capnographic monitoring. RESULTS: In 4,846 endoscopic procedures performed without capnography, adverse outcomes related to moderate sedation were noted in 14 cases (0.29%). A subset of patients at higher risk for moderate sedation was identified. There were no cases of oversedation in 600 cases monitored with capnography. The complication rates were not significantly different for the two groups ( p = 0.30, NS). CONCLUSION: The addition of capnography during moderate sedation endoscopy does not appear to significantly lower anesthesia-related morbidity. However, in cases requiring moderate sedation for prolonged procedures, in older patients with comorbidities, or in instances where respiratory excursion of the patient is obscured from view, practitioners should nonetheless consider capnography.
Adult↗
Capnometry and anaesthesia.
In the last decade, capnography has developed from a research instrument into a monitoring device considered to be essential during anaesthesia to ensure patient safety. Hence, a comprehensive understanding of capnography has become mandatory for the anaesthetist in charge of patients in the operating room and in the intensive care unit. This review of capnography includes the methods available to determine carbon dioxide in expired air, and an analysis of the physiology of capnograms, which are followed by a description of the applications of capnography in clinical practice. The theoretical backgrounds of the effect of barometric pressure, water vapour, nitrous oxide and other factors introducing errors in the accuracy of CO2 determination by the infra-red technique, currently the most popular method in use, are detailed. Physiological factors leading to changes in end-tidal carbon dioxide are discussed together with the clinical uses of this measurement to assess pulmonary blood flow indirectly, carbon dioxide production and adequacy of alveolar ventilation. The importance of understanding the shape of the capnogram as well as end-tidal carbon dioxide measurements is emphasized and its use in the early diagnosis of adverse events such as circuit disconnections, oesophageal intubation, defective breathing systems and hypoventilation is highlighted. Finally, the precautions required in the use and interpretation of capnography are presented with the caveat that although no instrument will replace the continuous presence of the attentive physician, end-tidal carbon dioxide monitoring can be effective in the early detection of anaesthesia-related intraoperative accidents.
Anesthesia↗
The tracheal detecting-bulb: a new device to distinguish tracheal from esophageal intubation.
BACKGROUND: The tracheal detecting-bulb (TDB) is a diagnostic tool for confirmation of tracheal intubation. Capnography is also accepted as a standard way for such confirmation. The purpose of this investigation was to determine whether the results by TDB agreed with those by capnography. METHODS: Four hundred patients were allocated to three separate studies. In 200 consecutive patients of study 1, tracheal intubation was first confirmed with the TDB followed by capnography. In study 2, 100 patients had the esophagus intentionally intubated, and confirmation was performed likewise as in study 1. The tube was then removed, the trachea was intubated, and confirmation tests followed. Study 3 involved 100 patients and was carried out in a double-blind, randomized manner. The tube was intentionally inserted into either the esophagus (n = 42) or trachea (n = 58), and confirmation tests immediately followed. RESULTS: In study 1, the rhythmic expansion-contraction of TDB was evident in 173 patients, and always agreed with capnographic reading; In 27 instances, the latex bulb of TDB remained collapsed or was scantily filled without the turning-up of capnographic reading as counterchecked, indicating esophageal intubation. In study 2, regardless of esophageal or tracheal intubation, agreement between TDB and capnogram was 100%. In study 3, the agreement between the two detecting instruments was 100% too. In the 400 patients studied, the results from the TDB were in complete accord with those of capnogram. The sensitivity, specificity, and predictive value of the TDB in all of these studies were 100%. CONCLUSIONS: The TDB is a valuable diagnostic technique for confirming tracheal intubation as it could correctly detect esophageal or tracheal intubation of the tracheal tube in all our 400 patients. The results of using TDB agree with the results of using capnography.
Adolescent↗
Prehospital determination of tracheal tube placement in severe head injury.
OBJECTIVES: The aim of this prospective study in the prehospital setting was to compare three different methods for immediate confirmation of tube placement into the trachea in patients with severe head injury: auscultation, capnometry, and capnography. METHODS: All adult patients (>18 years) with severe head injury, maxillofacial injury with need of protection of airway, or polytrauma were intubated by an emergency physician in the field. Tube position was initially evaluated by auscultation. Then, capnometry and capnography was performed (infrared method). Emergency physicians evaluated capnogram and partial pressure of end tidal carbon dioxide (EtCO(2)) in millimetres of mercury. Determination of final tube placement was performed by a second direct visualisation with laryngoscope. Data are mean (SD) and percentages. RESULTS: There were 81 patients enrolled in this study (58 with severe head injury, 6 with maxillofacial trauma, and 17 politraumatised patients). At the first attempt eight patients were intubated into the oesophagus. Afterwards endotracheal intubation was undertaken in all without complications. The initial capnometry (sensitivity 100%, specificity 100%), capnometry after sixth breath (sensitivity 100%, specificity 100%), and capnography after sixth breath (sensitivity 100%, specificity 100%) were significantly better indicators for tracheal tube placement than auscultation (sensitivity 94%, specificity 66%, p<0.01). CONCLUSION: Auscultation alone is not a reliable method to confirm endotracheal tube placement in severely traumatised patients in the prehospital setting. It is necessary to combine auscultation with other methods like capnometry or capnography.
Adult↗
End-tidal carbon dioxide monitoring: a VITAL sign worth watching.
Capnography is the monitoring of end-tidal carbon dioxide in waveform and numeric display. For this technology to be useful, the critical care nurse must have a clear understanding of the normal capnography waveform and what the alterations in this waveform represent. The critical care nurse can use this information to plan patient care interventions with other critical care team members and to adjust care based on the patient's response. End-tidal carbon dioxide physiology, normal waveforms, abnormal waveforms, and clinical aspects of capnography monitoring are included.
Airway Obstruction↗
Respiratory monitoring: arterial blood gas analysis, pulse oximetry, and end-tidal carbon dioxide analysis.
The use of arterial blood gas analysis, pulse oximetry, and capnography has become commonplace in the assessment of veterinary patients. Blood gas analysis allows for the qualitative and quantitative assessment of both metabolic and respiratory acid-base problems, including the interrelationships between ventilation, oxygenation, and metabolic conditions. Blood gas analysis is a useful adjunct to clinical patient assessment and other diagnostics in determining appropriate therapy for specific and complex conditions. Both pulse oximetry and capnography are useful monitoring tools. However, they have technical limitations and cannot comprehensively evaluate patient oxygenation and ventilation. Pulse oximetry and capnography are not replacements for arterial blood gas analysis, but rather serve as adjunctive monitoring tools.
Acidosis, Respiratory↗