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PubMed2002

Use of capnometry to verify feeding tube placement.

OBJECTIVE: To investigate the effectiveness of capnometry (carbon dioxide monitoring) in verifying gastric placement of a stylet-guided nasogastric tube in intubated, mechanically ventilated patients. DESIGN: A prospective descriptive study. SETTING: Fourteen-bed medical-surgical intensive care unit, 11-bed coronary care unit, and 18-bed chronic ventilator unit in a 700-bed teaching hospital. PATIENTS: A total of 53 adult patients on mechanical ventilation and enteral feedings. INTERVENTIONS: After the feeding tube was inserted to 30-cm length and before the first chest roentgenogram was taken, the end-tidal carbon dioxide detector was attached to the proximal end of the feeding tube. It was left in place for 1 min and was observed for a change in color (originally purple, it will turn tan or even yellow on contact with carbon dioxide). If the end-tidal carbon dioxide detector remained purple, it was interpreted as gastrointestinal placement; if it turned tan or yellow, it was interpreted as airway placement. The first chest roentgenogram was taken to confirm observations made with the end-tidal carbon dioxide detector. The feeding tube was advanced and a final chest roentgenogram verified its position below the diaphragm. MEASUREMENTS AND MAIN RESULTS: In 52 of the 53 placements, no carbon dioxide was detected. The position in the gastrointestinal tract was confirmed by the two-step procedure. There were no false positives; the technique was 100% specific. One placement out of the 53 was found to be in the trachea. The end-tidal carbon dioxide detector appropriately detected carbon dioxide. This indicated no false negatives. To verify the sensitivity, 20 placements were made directly into the trachea through an endotracheal tube. In all 20 cases, carbon dioxide was detected. No false negatives occurred, indicating 100% sensitivity. Testing in spontaneously breathing patients was not conducted. CONCLUSIONS: Capnometry is a safe method for verifying proper feeding tube placement. The first chest roentgeno-gram can be safely eliminated. With this method, less time and money will be expended in feeding tube placement, making capnometry an efficacious new method.

Aged↗
PubMed2001

New technologies in the assessment of hemodynamic parameters.

Pulmonary artery catheter (PAC) use has led to major advances in the assessment of hemodynamics. Since its introduction three decades ago, features have been added to the PAC to enhance its hemodynamic monitoring capabilities. In addition, newer technologies have been proposed to replace the PAC. This article discusses three features that enhance the PAC--measures of mixed venous oxyhemoglobin, right ventricular ejection fraction, and continuous cardiac output--and two newer technologies--esophageal Doppler and exhaled carbon dioxide measurements. The article describes current and future applications of hemodynamic monitoring.

Blood Gas Analysis↗
PubMed1996

Noninvasive capnometry in a pediatric population with respiratory emergencies.

OBJECTIVE: This study was designed to investigate the reliability, safety, and efficacy of measuring end tidal CO2 (ETCO2) in nonintubated pediatric patients presenting to an emergency department (ED) with respiratory emergencies. DESIGN/SETTING/PATIENTS: Eighty-five children were enrolled in a clinical, prospective, observational study at a university-affiliated children's hospital. Children age four weeks to 15.3 years with upper and lower respiratory diseases were enrolled by convenience sampling over a five-month period. INTERVENTIONS: ETCO2 measurements were obtained on each patient by oral/nasal side-stream capnometry. When a consistent waveform was obtained, the value was compared with a capillary arterial partial pressure of CO2 (CapCO2), oxygen saturation (O2Sat), and clinical observations. RESULTS: Study patients had a mean ETCO2 reading of 33 mmHg with a standard deviation (SD) of 4.6 mmHg and CapCO2 reading of 36 mmHg with a SD of 4.5 mmHg. Pulmonary findings, final diagnosis, and age did not significantly alter the relationship between CapCO2 and ETCO2. The relationship between CapCO2 and ETCO2 was significant (t = 14.9, P < 0.0001, r = 0.87), with a 95% confidence interval for prediction of +/-5 mmHg. CONCLUSION: Dependable ETCO2 values can be obtained using an oral/nasal capnometry circuit, and they consistently correlate with CapCO2 in a pediatric population with upper and lower respiratory diseases. Noninvasive ETCO2 analysis is safe and reliable within the limitations of this study group. Further exploration is necessary to determine the value of this technology in assisting with clinical decisions in the patient with impending respiratory failure.

Adolescent↗
PubMed1999

End-tidal carbon dioxide monitoring during sedation with a combination of midazolam and ketamine for children undergoing painful, invasive procedures.

BACKGROUND: Previous studies evaluating the respiratory effects of sedation regimens have focused on events such as a decline in O2 saturation or apnea. The current study used both end-tidal carbon dioxide (ETCO2) monitoring and pulse oximetry to evaluate the respiratory effects of midazolam and ketamine. METHODS: Fifty children who required sedation during invasive procedures formed the cohort for the study. During sedation, ETCO2 was sampled from nasal cannulae of spontaneously breathing patients and measured by a side-stream aspirating infrared device. RESULTS: During the procedure, O2 saturation decreased by 3% or more in three patients. Supplemental oxygen at 2 liters per minute was administered to these patients. The lowest oxygen saturation was 84%. During the total of 767 minutes of monitoring, there were 3068 ETCO2 values recorded. The high ETCO2 values ranged from 37 to 53 mmHg (40.5 +/- 3.3 mmHg). Ninety percent, or 2760, of the values were 40 mmHg or less, 7% or 214 were between 41 and 45 mmHg, 3% or 92 were between 46 and 49 mmHg, and 2 isolated values were greater than 50 mmHg. One episode of airway obstruction was identified by noting cessation of the ETCO2 waveform. This was relieved by repositioning the patient's airway. The three episodes of O2 desaturation, two ETCO2 values greater than 50 mmHg, and the episode of upper airway obstruction all occurred in three patients. Two of these patients had trisomy 21 with macroglossia, and the third had had a recent upper respiratory infection and a history of tonsillar hypertrophy. CONCLUSION: The incidence of adverse cardiorespiratory events associated with the current sedation regimen of midazolam-ketamine is lower than that reported with other commonly used regimens. The addition of ETCO2 monitoring provides an additional monitor to allow for early detection of airway obstruction or subclinical degrees of respiratory depression.

Capnography↗
PubMed2002

Evaluation of a Capno-Flo resuscitator during transport of critically ill children.

OBJECTIVES: Critically ill children often require endotracheal intubation prior to transport to a tertiary care center. Correct endotracheal tube (ETT) placement (trachea vs esophagus) and maintenance of ETT position during transport are of utmost importance. We evaluated the use of a Capno-Flo resuscitator (ventilation bag with a pH-sensitive colorimetric strip in the patient connector; Kirk Specialty Systems, Carrollton, TX) during transport of critically ill children. METHODS: Thirty-nine intubations were evaluated in 38 patients (one patient was intubated twice) aged 1 day to 19 years (median age, 13 mo) and weighing 0.9 to 80 kg (median weight, 11 kg) who were intubated and transported by air ( = 26, 68%) and ground ambulance ( = 12, 32%). ETT position was confirmed by physical examination, pulse oximetry, and in some patients, arterial blood gases and chest roentgenograms. ETT position was also assessed using the Capno-Flo after six breaths after intubation and was read as positive if the color changed from purple to yellow (tracheal tube position) and negative if the strip remained purple (esophageal tube position). The Capno-Flo ambu-bag was used continuously during transport and evaluated by the nurses or respiratory therapists, who also completed a brief questionnaire. RESULTS: Two esophageal and 37 tracheal tube positions were correctly identified by the device. There were no false-positive or false-negative results; the device was 100% sensitive and specific for the initial reading. It sometimes took longer to obtain this initial reading (> six breaths) in three patients. During transport, most personnel (36/38) noted minimal or no color change during inspiration and expiration, and therefore, it was not helpful in the continued verification of ETT position. CONCLUSIONS: The Capno-Flo resuscitator is useful in the initial confirmation of ETT position but not for continuous evaluation of ETT position during transport.

Adolescent↗
PubMedDate not supplied

Quantitative capnometry as a critical resuscitation tool.

Capnometry is a useful tool for emergency airway and ventilation management. Advantages include high sensitivity and specificity with regard to ET tube placement and the ability to provide continuous data throughout the initial resuscitation. Ultimately the ability of capnometry to guide ventilation and even chest compressions may be its most important contribution to the care of critically ill and injured patients.

Capnography↗
PubMed2003

Sublingual capnometry: an alternative to gastric tonometry for the management of shock resuscitation.

Normal vital signs do not reflect the physiologic aberrations after blood loss. Recognition of hypoperfusion during resuscitation can avoid the development of multiple organ failure. Advances in technology enable the clinician to monitor changes, potentially identifying tissue hypoxia much earlier than previously was possible. Gastric tonometry can be quite helpful in the intensive care unit in identifying gastric hypoperfusion, but has considerable drawbacks. The ability to monitor P(SI)CO(2) via sublingual capnometers overcomes some limitations of gastric tonometry and may be a valuable aid in the prehospital phase, the emergency department, and the intensive care unit in identifying end points of resuscitation.

Blood Volume↗
PubMed2001

Does the end-tidal carbon dioxide (EtCO2) concentration have prognostic value during out-of-hospital cardiac arrest?

We aimed to investigate the utility of end-tidal carbon dioxide concentration as a prognostic indicator of initial outcome of resuscitation, we conducted a prospective study of EtCO2 in adult victims of out-of-hospital non-traumatic cardiac arrest. We prospectively studied 139 adult patients. The initial, final, average, minimal and maximal EtCO2 was significantly higher in resuscitated patients than in non-resuscitated patients. Using an initial, average and final EtCO2 value of 10 mmHg correctly identified 100% of the patients who were subsequently resuscitated with an acceptable specificity (74.1%; 90%; 81.4%). Important observation from this study is that none of the patients with an average, initial and final EtCO2 level of less than 10 mmHg were resuscitated. Data from this prospective clinical trial indicate that initial, average and final EtCO2 monitoring during CPR is correlated with resuscitation. End-tidal CO2 monitoring has potential as a noninvasive indicator of cardiac output during resuscitation and a prognostic indicator for resuscitation.

Adult↗
PubMed2003

Sublingual capnometry versus traditional markers of tissue oxygenation in critically ill patients.

OBJECTIVE: The purpose of this study was to determine the prognostic value of sublingual PCO2 (P(SL)CO2), lactate concentration, and mixed venous oxygen saturation (S(MV)O2) in hemodynamically unstable intensive care patients and, additionally, to compare the temporal changes of these variables in response to treatment. SETTING: Medical/surgical intensive care unit. SUBJECTS: Fifty-four patients, mean age 58 +/- 8 yrs. INTERVENTIONS: Oxyhemodynamic variables, arterial lactate concentration, and P(SL)CO2 were recorded in unselected sequential intensive care patients undergoing pulmonary artery catheterization. A data set was obtained immediately after insertion of the pulmonary artery catheter and repeated 4 and 8 hrs later. MEASUREMENTS AND MAIN RESULTS: Twenty-one patients had severe sepsis or septic shock. Twenty-seven (50%) patients died. The initial P(SL)CO2_PaCO2 gradient (P(SL)CO2-diff) and the initial P(SL)CO2 were highly predictive of outcome (p =.0004 and p =.004, respectively); however, there was no difference in the arterial lactate concentration and S(MV)O2 between the survivors and nonsurvivors. The P(SL)CO2-diff had the best receiver operator characteristic characteristics (area under the curve, 0.75), with a P(SL)CO2-diff >25 mm Hg being the best discriminator of outcome. With treatment, the P(SL)CO2-diff decreased in both survivors and nonsurvivors; however, the lactate and S(MV)O2 remained relatively unchanged during the study period. CONCLUSIONS: The baseline P(SL)CO2-diff and P(SL)CO2 were better predictors of outcome than traditional markers of tissue hypoxia and were more responsive to therapeutic interventions. The P(SL)CO2-diff and/or P(SL)CO2 may prove to be a useful marker for goal-directed therapy and for assessing the response to clinical interventions aimed at improving tissue oxygenation.

APACHE↗
PubMed2006

Gastric and sublingual capnometry.

PURPOSE OF REVIEW: Tissue hypoperfusion is a common pathophysiologic process leading to multiple organ dysfunction and death. Increases in tissue PCO2 can reflect an abnormal oxygen supply to the cells, so that monitoring tissue PCO2 by the use of gastric or sublingual capnometry may help identify circulatory abnormalities and guide their correction. This review provides an update on these technologies. RECENT FINDINGS: Gastric tonometry aims at monitoring PCO2 in the stomach, an organ that becomes ischemic quite early when the circulatory status is jeopardized. Despite substantial initial enthusiasm, this technique has never been widely implemented due to methodological problems. The measurement of sublingual mucosal PCO2 (PslCO2) by sublingual capnometry is technically simple and noninvasive. Experimental studies have suggested that PslCO2 is a reliable marker of tissue perfusion. Clinical studies have demonstrated that high PslCO2 values are associated with impaired microcirculatory blood flow and a worse prognosis in critically ill patients. SUMMARY: Gastric tonometry was proposed for regional PCO2 monitoring, but it is prone to a number of technical limitations. Sublingual capnometry could offer a valuable alternative for tissue PCO2 monitoring in clinical practice, representing a simple, noninvasive method to monitor tissue perfusion and titrate therapeutic interventions in critically ill patients.

Capnography↗
PubMed2006

Vacuum-assisted closure of the sternotomy wound: respiratory mechanics and ventilation.

BACKGROUND: Numerous authors have reported promising results with the use of vacuum-assisted closure therapy in poststernotomy mediastinitis. The negative pressure applied to the anterior mediastinum substantially exceeds the normal negative pressure in the pleural cavities, and interaction with respiratory physiology cannot be excluded. The aim of the present study was to evaluate whether the application of six clinically relevant negative pressures between -50 mmHg and -175 mmHg to the sternotomy wound affects respiratory parameters in a porcine model. METHODS: A midline sternotomy was performed in six mechanically ventilated pigs weighing 70 +/- 3 kg. Vacuum-assisted closure therapy was applied with continuous negative pressure in a randomized order to the sternotomy wound. The following respiratory parameters were monitored by a carbon dioxide-based noninvasive monitoring system connected to the ventilator: carbon dioxide elimination, peak inspiratory pressure, peak expiratory flow, alveolar minute volume, alveolar tidal volume, expired tidal volume, static compliance, and airway resistance. RESULTS: All pigs survived the treatment, and there was no significant change in the respiratory parameters investigated at any of the six negative pressures applied. A tendency toward increased airway resistance was noted when -175 mmHg was applied, although this change was not significant. CONCLUSIONS: The application of negative pressure therapy in the treatment of deep poststernotomy infections is a novel modality gaining increased attention. In this study, no impairment in respiratory mechanics, ventilation, or oxygenation was detected when comparing applied pressures ranging from -50 mmHg to -175 mmHg in the sternotomy wound.

Airway Resistance↗
PubMed2004

Prehospital end-tidal carbon dioxide concentration and outcome in major trauma.

BACKGROUND: End-tidal carbon dioxide (Petco2) concentration is a marker of the pathophysiologic state because it is a reflection of cardiac output. Petco2 correlates with outcome after prehospital primary cardiac arrest, but association with outcome from prehospital trauma has not been established. METHODS: Between 1998 and 2001, Petco2 was recorded in 191 blunt trauma patients requiring prehospital intubation. Rapid sequence intubation was performed using suxamethonium (1 mg/kg) and etomidate (0.2-0.3 mg/kg). Initial Petco2 after endotracheal intubation (t0) and Petco2 at 20 minutes after endotracheal intubation (t20) were recorded, together with survival to discharge. RESULTS: Median Petco2 at t20 was 4.10 kPa in survivors and 3.50 kPa in nonsurvivors (95% confidence interval of difference between medians, 0.40 to 0.90 kPa; p < 0.0001). Petco2 at t20 was a better predictor of outcome than at t0. CONCLUSION: Only 5% patients with Petco2 < 3.25 kPa survived to discharge. Petco2 at t20 is of value in predicting outcome from major trauma.

Adolescent↗
PubMed2003

Vagal nerve stimulation induces intermittent hypocapnia.

PURPOSE: To study whether respiratory alteration caused by vagal nerve stimulation (VNS) can change end-tidal carbon dioxide (EtCO2) levels. METHODS: We performed polygraphic recordings including capnographic monitoring during daytime sleep on adults with VNS therapy. RESULTS: Ten of 13 patients showed VNS-induced alterations in the frequency or amplitude of respiration. Five patients had a consistent increase in respiratory rate with a simultaneous, consistent and significant decrease (p < 0.01; 5-22%) in EtCO2 during VNS. Three subjects showed occasional decreases in EtCO2 during VNS, and two showed no clearly detectable VNS-related EtCO2 changes. CONCLUSIONS: Our findings suggest that VNS may alter brain CO2 levels through changes in respiration. Because carbon dioxide (CO2) has potent effects on various brain functions, it is possible that these transient CO2 changes may have an effect on the state transitions between interictal and preictal states.

Adult↗