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At least 433 records · Page 24Linked to original sources
PubMed2005

Continuous end-tidal carbon dioxide monitoring for confirmation of endotracheal tube placement is neither widely available nor consistently applied by emergency physicians.

OBJECTIVES: To determine the availability of end-tidal CO2 measurement in confirmation of endotracheal tube placement in the non-arrest patient, and to assess its use in academic and non-academic emergency departments. METHODS: Emergency physicians in the USA were surveyed by mail in the beginning of the year 2000 regarding availability at their institution of both colorimetric/qualitative and quantitative end-tidal CO2 capnography, frequency of use in their own practice, and descriptor of their hospital (academic, community teaching, and community non-teaching). Additionally, data were obtained from the National Emergency Airway Registry 97 series (NEAR) about how many intubations used this method of confirmation. NEAR site coordinators were surveyed as well. RESULTS: Of 1000 surveys, 550 were returned (55%). Colorimetric technology existed in 77% of respondents' hospitals (n = 421); 25% of respondents (n = 138) had continuous monitoring capability. Physicians practising at academic hospitals were more likely to have continuous monitoring (36%; n = 196) than community teaching institutions (32%; n = 173) and non-teaching centres (18%; n = 100) (p<0.001). Among physicians who had this technology available, only 14% (n = 19) "always" used it in non-arrest intubations; 57% "rarely" or "never" employed it (n = 75). Among NEAR centres (institutions committed to monitoring current airway practices) only 12% of 6009 (n = 716) intubations used continuous end-tidal CO2 measurement. Of these practitioners, only 40% "always" used it (n = 6/15) (83% response rate (n = 29/35)). CONCLUSIONS: Despite recommendations from national organisations that endorse continuous monitoring of end-tidal CO2 for confirming endotracheal tube placement, it is neither widely available nor consistently applied.

Capnography↗
PubMed2001

Non-invasive cardiac output determination: comparison of a new partial-rebreathing technique with thermodilution.

This study compares a derivative Fick technique using carbon dioxide (CO2) with the thermodilution pulmonary artery catheter (PAC), for determination of cardiac output (CO). Subjects were sedated, mechanically ventilated adults following elective cardiac surgery Microprocessor controlled deadspace activation and side-stream capnography in a ventilator circuit enabled calculation of CO (CO(CO2)) every four minutes. Thermodilution CO (CO(TD)) was performed as clinically indicated and at 20-minute intervals. Simultaneous CO(TD)/CO(CO2) pairs were recorded from time of admission to ICU for a minimum period of two hours for each patient. There were 358 CO(TD)/CO(CO2) pairs recorded from 41 patients. Cardiac output measurements ranged from 2. 7 to 10.6 l/min. The bias (Bland-Altman) was 0.050 l/min (95% CI -0.024 to 0.125 l/min). The 95% limits of agreement were -1.354 to 1.455 l/min. This simple, non-invasive partial-rebreathing technique is a valid alternative to thermodilution for cardiac output determination in sedated, mechanically ventilated patients. There are significant implications for improved safety, reduced complexity and reduced cost in anaesthesia and intensive care.

Adult↗
PubMed1996

A simple method for frequent monitoring of gastric carbon dioxide.

Intragastric PCO2 has been recognized to rise in states of gastric hypoperfusion. A device including a gas-permeable balloon on a conventional sump nasogastric tube (TRIP catheter, Tonometrics) has permitted simple measurement of the intragastric PCO2 following equilibration of intragastric PCO2 with saline in the balloon. This method is slow to equilibrate and time-consuming. We describe an automated method using air instead of saline in the balloon with measurement using capnography. Equilibration is much faster using air and the automated system permits measurements to be taken at regular intervals (10 minutes) without additional workload.

Air↗
PubMed2004

Carbon dioxide monitoring and evidence-based practice - now you see it, now you don't.

Carbon dioxide has been monitored in the body using a variety of technologies with a multitude of applications. The monitoring of this common physiologic variable in medicine is an illustrative example of the different levels of evidence that are required before any new health technology should establish itself in clinical practice. End-tidal capnography and sublingual capnometry are two examples of carbon dioxide monitoring that require very different levels of evidence before being disseminated widely. The former deserves its status as a basic standard based on observational data. The latter should be considered investigational until prospective controlled data supporting its use become available. Other applications of carbon dioxide monitoring are also discussed.

Anesthesia, Endotracheal↗
PubMed1999

Neural network analysis of the volumetric capnogram to detect pulmonary embolism.

BACKGROUND: Pulmonary embolism (PE) produces ventilation/perfusion mismatch that may be manifested in various variables of the volume-based capnogram (VBC). We hypothesized that a neural network (NN) system could detect changes in VBC variables that reflect the presence of a PE. METHODS: A commercial VBC system was used to record multiple respiratory variables from consecutive expiratory breaths. Data from 12 subjects (n = 6 PE+ and n = 6 PE-) were used as input to a fully connected back-propagating NN for model development. The derived model was tested in a prospective, observational study at an urban teaching hospital. Volumetric capnograms were then collected on 53 test subjects: 30 subjects with PE confirmed by pulmonary angiography or diagnostic scintillation lung scan, and 23 subjects without PE based on pulmonary angiography. The derived NN model was applied to VBC data from the test population. RESULTS: Seventeen VBC variables were used by the derived NN model to generate a numeric probability of PE. When the derived NN model was applied to VBC data from the 53 test subjects, PE was detected with a sensitivity of 100% (95% CI = 89% to 100%) and a specificity of 48% (95% CI = 27% to 69%). The likelihood ratio positive [LR(+)] for the VBC-NN test was 1.82 and the LR (-) was 0.1. CONCLUSION: This study demonstrates the feasibility of developing a rapid, noninvasive breath test for diagnosing PE using volumetric capnography and NN analysis.

Angiography↗
PubMed2006

End-tidal carbon dioxide as a measure of acidosis among children with gastroenteritis.

OBJECTIVES: We aimed to determine the correlation between end-tidal carbon dioxide levels and serum bicarbonate concentrations among patients with gastroenteritis, to compare the end-tidal carbon dioxide with other clinical parameters that might also be associated with the degree of acidosis, and to examine the relationship between end-tidal carbon dioxide levels and return visits. METHODS: Our prospective sample included patients presenting to the emergency department with a chief complaint of vomiting and/or diarrhea. The association between end-tidal carbon dioxides and serum bicarbonate concentrations was determined with simple linear-regression analysis. Receiver operating characteristic curves were computed to determine the predictive ability of the end-tidal carbon dioxide to detect metabolic acidosis. RESULTS: One hundred thirty of 146 subjects who were approached were included in the final analysis. For those for whom laboratory studies were performed, the mean serum bicarbonate concentration was 17.3 +/- 4.3 mmol/L and the mean end-tidal carbon dioxide level was 34.2 +/- 5.2 mm Hg. End-tidal carbon dioxide levels and serum bicarbonate concentrations were correlated linearly in bivariate analysis. Receiver operating characteristic curves were calculated for end-tidal carbon dioxide as a predictor of serum bicarbonate concentrations of < or = 13, < or = 15, and < or = 17 mmol/L, with areas under the curves of 0.94, 0.95, and 0.90, respectively. The relationship between end-tidal carbon dioxide levels and serum bicarbonate concentrations was independent of other potential predictors of acidosis in multivariable analysis. The mean end-tidal carbon dioxide level for patients who required an unanticipated return visit (33.0 +/- 4.0 mm Hg) was lower than the level for those who did not seek reevaluation (36.6 +/- 3.6 mm Hg). CONCLUSIONS: End-tidal carbon dioxide levels were correlated with serum bicarbonate concentrations among children with vomiting and diarrhea, independent of other clinical parameters. Capnography offers an objective noninvasive measure of the severity of acidosis among patients with gastroenteritis.

Acidosis, Respiratory↗
PubMed2003

Effects of IV pentobarbital with and without fentanyl on end-tidal carbon dioxide levels during deep sedation of pediatric patients undergoing MRI.

OBJECTIVE: IV pentobarbital is used in radiology departments for sedating pediatric patients undergoing diagnostic imaging. To our knowledge, no published studies have documented end-tidal carbon dioxide levels during sedation with IV pentobarbital. The purpose of this prospective study was to determine the effects of different doses of IV pentobarbital with or without fentanyl on end-tidal carbon dioxide levels during deep sedation of pediatric patients undergoing MRI. SUBJECTS AND METHODS: One hundred sixty-five patients (70 girls, 95 boys) having a mean age of 3.4 years received IV pentobarbital sedation with or without fentanyl for undergoing MRI from January through March 2002. Each child was sedated with 2-6 mg/kg of body weight of IV pentobarbital and an additional 1-3 micro g/kg of fentanyl if needed. After the administration of sedation, a 28-ft (8.5 m) nasal cannula with capnography capability was applied to each patient, and capnogram tracings and values were recorded every 5 min. RESULTS: Mean values of end-tidal carbon dioxide were between 37 and 42 mm Hg during 60 min of sedation for both groups. When IV pentobarbital was used alone, no significant difference was seen between patients who received 3-5 mg of pentobarbital and those who received more than 5 mg (p = 0.97, F test). CONCLUSION: End-tidal carbon dioxide levels remain within normal clinical range during sedation with IV pentobarbital with or without fentanyl. Our sedation protocol produced no significant deviations from normal respiratory parameters.

Adjuvants, Anesthesia↗
PubMed2001

Capnographic monitoring of anesthetized African grey parrots receiving intermittent positive pressure ventilation.

OBJECTIVE: To determine whether end-tidal partial pressure of carbon dioxide (PETCO2) correlated with PaCO2 in isoflurane-anesthetized African grey parrots receiving intermittent positive pressure ventilation (IPPV). DESIGN: Prospective study. ANIMALS: 14 healthy mature African grey parrots (Psittacus erithacus timnus). PROCEDURE: Each bird was anesthetized via mask with isoflurane, intubated, and connected to a pressure-limited intermittent-flow ventilator. Respiratory rate was altered while holding peak inspiratory pressure constant (5 cm H2O) to achieve a PETCO2 in 1 of 3 ranges: < 30 mm Hg, 30 to 40 mm Hg, and > 40 mm Hg. Blood was collected from the superficial ulnar artery of each bird at least once during each of the 3 ranges. Arterial blood samples were collected for blood gas analysis while PETCO2 was recorded simultaneously. RESULTS: A strong correlation between PETCO2 and PaCO2 was detected over a wide range of partial pressures, although PETCO2 consistently overestimated PaCO2 by approximately 5 mm Hg. End-tidal partial pressure of CO2 and PaCO2 also correlated well with arterial blood pH, and the acute response of the bicarbonate buffer system to changes in ventilation was similar to that of mammals. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that PETCO2 reliably estimates PaCO2 in isoflurane-anesthetized African grey parrots receiving IPPV and suggest that IPPV combined with capnography is a viable option for anesthetic maintenance in avian anesthesia.

Anesthesia, Inhalation↗
PubMed1999

Noninvasive respiratory monitoring.

Advances in technology now permit a variety of noninvasive respiratory monitoring options for clinicians. Perhaps a more complex issue is determining how much monitoring is needed as part of routine patient care. Often, practitioners take a "more is better" approach. This reasoning is justified in critical care, because, in theory, the more information clinicians have available to them, the more likely they are to make accurate assessments and proper therapeutic interventions. If one fails to properly understand the physiologic significance and clinical limitations of the numbers or waveforms from the monitor, however, patient care may not improve and, even worse, may be compromised. Therefore, proper training in all aspects of respiratory monitoring should be a basic and fundamental component of any critical care nurse training program. There are important cost considerations to be taken into account with continuous respiratory monitoring. The financial impact as it relates to care of the critically ill patient is often difficult to assess. Issues of cost-effectiveness are often justified because of the complex nature of caring for these patients and their need for intensive clinical observation and evaluation. The fact that many aspects of cardiopulmonary assessment can now be determined noninvasively is an important advantage over more invasive technologies and their associated risks. Clearly, monitoring techniques such as pulse oximetry and capnography do not eliminate the need for arterial blood gases and other invasive cardiopulmonary monitoring techniques. Rather, when appropriately applied, noninvasive monitoring has the potential to reduce the frequency of certain invasive procedures and still provide valuable information to nurses and other health care practitioners.

Airway Resistance↗
PubMedDate not supplied

Non-invasive respiratory monitoring in paediatric intensive care unit.

Monitoring respiratory function is important in a Paediatrics Intensive Care Unit (PICU), as majority of patients have cardio-respiratory problems. Non-invasive monitoring is convenient, accurate, and has minimal complications. Along with clinical monitoring, oxygen saturation using pulse oximetry, transcutaneous oxygenation (PtcO2) and transcutaneous PCO2 (PtcCO2) using transcutaneous monitors and end-tidal CO2 using capnography are important and routine measurements done in most PICUs. Considering the financial and maintenance constraints pulse oximetry with end tidal CO2 monitoring can be considered as most feasible.

Capnography↗
PubMedDate not supplied

[Radiotherapy treatment under anesthesia in pediatrics].

A four-year-old boy received 30 sessions of radiotherapy, at a rate of one session daily for five days every week, under anesthesia with midazolam and propofol in spontaneous ventilation. Monitoring was by pulse oximetry and capnography; no adverse events were recorded. The presence of an anesthesiologist during diagnostic and therapeutic procedures outside the operating room is essential, given that lack of cooperation can make the procedure difficult or impossible to perform. Radiotherapy under anesthesia is a special case because it is scheduled daily, and care must be taken to interfere as little as possible with a child's meals or other activities.

Anesthesia, General↗
PubMed2005

Capnographic waveforms in the mechanically ventilated patient.

A focus on patient safety has heightened the awareness of patient monitoring. The importance of clinical applications of capnography continues to grow, as reflected by the increasing number of medical societies recommending its use. Recognition of changes in the capnogram assists in clinical decision making and treatment and can increase patient safety by alerting the clinician to important situations and changes. This article describes the interpretation of capnograms and how capnogram interpretation influences airway management.

Capnography↗
PubMed2006

Dose end-tidal carbon dioxide measurement correlate with arterial carbon dioxide in extremely low birth weight infants in the first week of life?

OBJECTIVE: To study the correlation and agreement between end-tidal carbon dioxide (EtCO2) and arterial carbon dioxide (PaCO(2)) in ventilated extremely low birth weight (ELBW) infants in the first week of life. METHODS: Retrospective chart review of all ELBW (<1,000 g) infants admitted to a level III NICU from January 2003 to December 2003. Data collected included demographic details and simultaneous EtCO(2) (mainstream capnography) and arterial blood gas values (pH, PaCO(2), PaO(2)). OUTCOME: The correlation coefficient, degree of bias with 95% confidence interval between the EtCO(2) and PaCO(2). RESULTS: There were 754 end-tidal and arterial CO(2) pairs from 31 ELBW infants (21 male and 10 female). The overall EtCO(2) values were significantly lower than PaCO(2) value. In only 89/754(11.8%) pairs, the EtCO(2) was higher than the PaCO(2). The overall bias was 5.6 +/- 6.9 mmHg (95% C.I. 5.11-6.09). The intraclass correlation coefficient was 0.81. Using EtCO2 ranges of 30 to 50 mmHg, the capnographic method was able to identify 84% of instances where PaCO(2) was between 35 (<35 = hypocarbia) and 55 mmHg (>55= hypercapnia). CONCLUSIONS: There is good correlation and agreement between end-tidal CO(2) and arterial CO(2) in ELBW infants in the EtCO(2) range 30-50 mmHg. End-tidal CO(2) monitoring can be helpful in trending or for screening abnormal PaCO(2) values in ELBW infants in first week of life.

Blood Gas Analysis↗
PubMed1998

Assessment of ventilation during the performance of a percutaneous dilatational tracheostomy: hypoventilation is not a common complication.

Percutaneous dilatational tracheostomy (PDT) is becoming an accepted cost-effective alternative to surgical tracheostomy. PDT is performed by progressive dilatation of a tracheal opening placed under bronchoscopic guidance. Case reports of hypoventilation with associated hypercarbia during the performance of PDT have raised concerns about the utility of this procedure in patients in whom hypercarbia is problematic (e.g., patients with closed head injury). In a prospective cohort analysis of 11 critically ill patients, we evaluated the effect of PDT on ventilation during and after the procedure using end tidal capnography. We found that hypercarbia does not occur during or after the performance of PDT as compared to baseline levels.

Bronchoscopes↗
PubMedDate not supplied

Correlation of the end-tidal PCO2 during laparoscopic surgery with the pH of the gastric juice.

BACKGROUND AND OBJECTIVES: During laparoscopy, the increase of the carbon dioxide tension may increase the synthesis of hydrochloric acid in the parietal cells of the stomach; the source of the secreted hydrogen ions is carbonic acid derived from the hydration of carbon dioxide. The present report tests this hypothesis by correlating the changes of end-tidal PCO2 (ETCO2) with the pH of the gastric juice in patients undergoing laparoscopic cholecystectomy. METHODS: 40 adult patients were investigated: 20 controls, and 20 patients receiving 100 mg nizatidine intravenously, prior to surgery. In both groups, the ETCO2 was measured by capnography and the pH of the gastric juice was monitored before carbon dioxide insufflation and at the end of laparoscopy prior to carbon dioxide deflation. RESULTS: In the control group, the ETCO2 increased following carbon dioxide insufflation from a mean basal value of 30.2 (standard deviation [SD] 4.6) mm Hg to 41.1 (SD 9.5) mm Hg, while the mean pH of the gastric juice decreased significantly from 1.9 (SD 0.4) to 1.27 (SD 0.43). There was a significant negative correlation between the ETCO2 and pH of the gastric juice (r = -0.4). In the Nizatidine group, the ETCO2 also increased following carbon dioxide insufflation from a mean basal value of 30.9 (SD 3.0) mm Hg to 39.4 (SD 5.3) mm Hg. However, in contrast with the control group, the mean pH of the gastric juice did not decrease, but paradoxically increased from 1.68 (SD 0.36) to 3.6 (SD 1.02). CONCLUSIONS: During laparoscopy, the pH of the gastric juice is significantly decreased. This decrease is inversely related to the increase of ETCO2. The preoperative administration of the selective H2-blocker nizatidine can prevent the increase in gastric acidity and can result in a paradoxical increase of pH of the gastric juice.

Capnography↗
PubMed2005

Continuous noninvasive monitoring of transcutaneous blood gases for a stable and persistent BOLD contrast in fMRI studies in the rat.

The physiological status of anesthetized rats greatly influences blood oxygenation level dependent (BOLD) functional magnetic resonance imaging (fMRI). Monitoring of physiological parameters, particularly partial pressure of carbon dioxide (pCO(2)) levels in the blood, is therefore an important part in the design and performance of reliable fMRI experiments. In this paper, the use of a transcutaneous blood gas analyzing system in rats as a completely noninvasive and MR-compatible method is demonstrated. It was successfully used to monitor continuously pCO(2) values, as an effective alternative to more invasive methods, such as analysis of repetitive arterial blood samples or endtidal capnography. In addition, the transcutaneous pCO(2) of rats anesthetized for long periods was studied using different anesthetic substances and experimental protocols. On-line monitoring of pCO(2) values permitted experimental conditions to be established in which the animals remained normocapnic and during which a robust and consistent BOLD contrast could be observed upon somatosensory forepaw stimulation. A transcutaneous pCO(2) threshold level was defined for the reliable detection of a stimulus-dependent BOLD response.

Adult↗
PubMed1995

Carbon dioxide pneumoperitoneum induces fetal acidosis in a pregnant ewe model.

The objective of this study was to evaluate the physiologic consequences of a pneumoperitoneum (pneumo) to the midterm fetus in a pregnant sheep model. The performance of laparoscopic cholecystectomy (LC) during pregnancy is controversial. The primary concern regarding the safety of LC during pregnancy is the physiologic consequences of the CO2 pneumo to the fetus. Eight ewes with singlet pregnancies between 100 and 120 days of gestation were anesthetized and intubated. Carotid artery and internal jugular catheters were placed in the ewe and in the fetus. Two trocars were placed through the abdominal wall of the ewe and the abdomen was inflated with CO2 or N2O at 15 mmHg pressure for 90-120 min. Hemodynamic and blood gas data were obtained every 15 min before, during, and after the pneumo. In two ewes attempts were made to keep maternal Pco2 constant with hyperventilation. In two other animals the pneumo was increased stepwise in five mmHg increments to 25 mmHg. One fetus succumbed during the CO2 pneumo, but this animal appeared to be ill during the establishment of invasive monitoring. Fetal respiratory acidosis occurred, reproducibly, after establishment of CO2 pneumo but did not occur before insufflation or under N2O pneumo (P < 0.0001). Hemodynamic changes were minimal with all agents but it appeared that there a was greater prevalence of fetal tachycardia and hypertension during CO2 pneumo than during N2O pneumo. Alterations in ventilator settings based on maternal capnography resulted in late and incomplete correction of respiratory acidosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Acidosis, Respiratory↗
PubMed1995

Rebreathing improves accuracy of ventilatory monitoring.

OBJECTIVE: Our objective was to determine if rebreathing would reduce the gradient between arterial and end-tidal CO2 tension during positive-pressure ventilation. METHODS DESIGN: Experimental investigation. SETTING: Anesthesiology laboratory. SUBJECTS: A total of 10 dogs of either sex. INTERVENTIONS: Anesthesia (sodium pentobarbital) and muscle relaxation (pancuronium) were induced and animals were tracheally intubated and ventilated with a standard anesthesia ventilator and breathing circuit with CO2 absorber and then with a Mapleson D circuit with a fresh gas flow rate (VF) equal to alveolar ventilation plus the sampling flow rate of two capnometers. Rebreathing was varied by adjusting the respiratory rate (RR) so that minute ventilation (VE) to VF ratio was 1:1, 2:1, 3:1, and 4:1. RESULTS: CO2 production (ATPD) was determined as the product of expired concentration of CO2 and VE (BTPS). Alveolar ventilation (VA) was calculated by dividing the product of CO2 production and barometric pressure corrected for ambient temperature and water vapor pressure at body temperature by PaCO2. Tidal volume, RR, airway gas temperature, concentration of CO2 in gas at the tracheal tube and inlet/outlet of the mechanical ventilator, body temperature, arterial gas tensions and pH, heart rate, arterial blood pressure, and cardiac output were measured. Minute ventilation, mean arterial blood pressure and end-expiratory CO2 tension (PECO2) (BTPS) were calculated. During positive-pressure ventilation, concentration of inspired CO2 was zero with standard circuitry, and significantly increased with Mapleson D when VE:VF ratio was 1:1 (0.56 +/- 0.19%), 2:1 (1.97 +/- 1.30%), 3:1 (2.56 +/- 1.05%), and 4:1 (3.01 +/- 1.45%) (p < 0.05). PECO2 was 34.8 +/- 3.2 mm Hg during ventilation with the standard circuit, and significantly increased during ventilation with Mapleson D when VE:VF ratio was increased from 1:1 (35.4 +/- 2.5 mm Hg) to 2:1 (40.2 +/- 3.6 mm Hg) and was not further increased at a VE:VF ratio of 3:1 (41.8 +/- 2.7 mm Hg) or 4:1 (41.3 +/- 2.4 mm Hg). The selected fresh gas flow rate was appropriate, because PaCO2 remained unchanged regardless of VE:VF ratio, indicating PaCO2 was dependent on VF, not on VE. The gradient between PaCO2 and PECO2 during ventilation with the standard circuit was 6.6 +/- 3.0 mm Hg; during ventilation with Mapleson D, it decreased significantly when VE:VF ratio was increased from 1:1 (6.5 +/- 3.6 mm Hg) to 2:1 (2.9 +/- 1.5 mm Hg), but was not significantly reduced further at 3:1 (1.7 +/- 1.1 mm Hg) or 4:1 (1.8 +/- 0.5 mm Hg) (p < 0.05). CONCLUSIONS: Rebreathing with a Mapleson D circuit and a VF equal to VA permitted normal CO2 elimination. Arterial PCO2 to PECO2 gradient decreased significantly during rebreathing, thus improving the reliability of capnography for estimating arterial PCO2. Consideration should be given to using the Mapleson D as a rebreathing circuit.

Anesthesia, Closed-Circuit↗