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16 results

  • 12 - Severe pelvic trauma

  • from Section 2 - Trauma
  • Edited by Kaushal Shah, Jarone Lee, Kamal Medlej, American University of Beirut, Scott D. Weingart
  • Book:
    Practical Emergency Resuscitation and Critical Care
    Published online:
    05 November 2013
    Print publication:
    24 October 2013, pp 90-95

  • Summary

    This chapter discusses the basic methods and principles of monitoring for proper management of the critically ill patient in the emergency setting. Pulse oximetry provides continuous measurement of a patient's oxygenation status in the case of respiratory monitoring. Capnography measures the partial pressure or concentration of expired carbon dioxide (CO2), the end-tidal carbon dioxide (EtCO2). Ultrasonography of the inferior vena cava (IVC) can be useful in determining fluid responsiveness during non-invasive hemodynamic monitoring. Invasive hemodynamic monitoring provides data via catheters inserted in central veins or arteries. Central venous pressure is obtained by placing a central venous catheter (CVC) in the internal jugular or subclavian vein. The CVP should be interpreted with caution in critically ill patients that have known heart disease or structural cardiac anomalies. Pulse pressure variation (PPV) and systolic pressure variation (SPV) can be used to determine fluid responsiveness in a mechanically ventilated patient.

  • 18 - Volumetric capnography for monitoring lung recruitment and PEEP titration

  • from 1 - Ventilation
  • Edited by J. S. Gravenstein, University of Florida, Michael B. Jaffe, Nikolaus Gravenstein, University of Florida, David A. Paulus, University of Florida
  • Book:
    Capnography
    Published online:
    05 August 2011
    Print publication:
    17 March 2011, pp 160-168

  • Summary

    Capnography and capnometry provide useful information that may help improve decision-making and reduce complications during transport. This chapter reviews specific clinical applications of capnography and capnometry: assuring proper endotracheal tube placement, monitoring airway circuit integrity, monitoring the consistency of mechanical ventilation, improving safety in procedural sedation, assessing cardiac output, and evaluating patients in cardiac arrest. Capnometry and capnography aid in the confirmation of correct endotracheal tube placement. End-tidal CO2 (ETCO2) measurement can accurately detect esophageal intubation because CO2 is exhaled through the trachea, and not the esophagus. Once an airway device is in place, continuous monitoring is important to assure ventilator circuit patency, including that of the endotracheal tube, and to assure consistent levels of ventilation. Capnography is the gold standard for monitoring patients on airway appliances and ventilator circuits, and there are useful roles for the technology during procedural sedation and evaluating patients in the time surrounding arrest states.

  • 40 - Brief history of time and volumetric capnography

  • from 1 - Ventilation
  • Edited by J. S. Gravenstein, University of Florida, Michael B. Jaffe, Nikolaus Gravenstein, University of Florida, David A. Paulus, University of Florida
  • Book:
    Capnography
    Published online:
    05 August 2011
    Print publication:
    17 March 2011, pp 415-429

  • Summary

    Veterinarians familiar with capnography have frequently encountered technical difficulties associated with the use of older or less expensive capnometers, especially when sampling respiratory gas from relatively small, spontaneously breathing, anesthetized animals that frequently demonstrate altered patterns of breathing. Volumetric capnography simultaneously measures expired CO2 and tidal volume, facilitating the identification of CO2 from three sequential compartments: apparatus (anesthetic equipment), anatomic deadspace, and progressively emptying alveoli (alveolar gas). Although mammalian respiratory anatomy and function are remarkably similar among species, there are obvious allometric differences. Capnography in animals such as rodents and birds, nevertheless, remains challenging. A wide range of respiratory volumes exists among animal species. There is remarkable similarity in arterial blood pH and gas values. Capnometry is more commonly used to monitor ventilation in anesthetized horses. Capnography has also been used to evaluate pulmonary function in awake dolphins.

  • 13 - Capnometry monitoring in high- and low-pressure environments

  • from 1 - Ventilation
  • Edited by J. S. Gravenstein, University of Florida, Michael B. Jaffe, Nikolaus Gravenstein, University of Florida, David A. Paulus, University of Florida
  • Book:
    Capnography
    Published online:
    05 August 2011
    Print publication:
    17 March 2011, pp 115-126

  • Summary

    The ability to safely and effectively manage the airway is among the most fundamental and challenging aspects of out-of-hospital (OOH) emergency medical treatment. Commonly used devices to facilitate OOH airway management encompass a spectrum from basic means, such as the bag-valve mask (BVM), to more advanced and invasive means, such as the esophageal-tracheal combitube, laryngeal mask airway (LMA), laryngeal tube airway (LT), endotracheal tube (ET), and, ultimately, emergency surgical airways. End-tidal carbon dioxide (PetCO2) monitoring has emerged as the technology that can best confirm endotracheal or endobronchial location of an endotracheal tube. The threshold for detection of exhaled CO2 is significantly lower for capnometry and capnography as opposed to colorimetric devices. The use of capnography for OOH airway management enhances patient safety and can prevent the problem of unrecognized misplaced intubation (UMI) and should be a mandatory component of OOH airway management.

  • 19 - Capnography and adjuncts of mechanical ventilation

  • from 1 - Ventilation
  • Edited by J. S. Gravenstein, University of Florida, Michael B. Jaffe, Nikolaus Gravenstein, University of Florida, David A. Paulus, University of Florida
  • Book:
    Capnography
    Published online:
    05 August 2011
    Print publication:
    17 March 2011, pp 169-182

  • Summary

    It is important to keep in mind the differences between PETCO2, alveolar CO2, and arterial PCO2 (PaCO2) as extremes of temperature and altitude, and the potential for sensor interference by condensation or various body fluids, may significantly affect the performance of these devices. This chapter presents the evidence for use of PETCO2 monitoring to guide ventilation in the field and reviews each type of device available, discussing the advantages and disadvantages of each. In theory, monitoring of PETCO2 data should lead to a low incidence of hyperventilation, regardless of whether manual or mechanical ventilation is used. Quantitative capnometry has great potential for guiding ventilation in the prehospital arena. Advances in the technology for PETCO2 monitoring, including capnometry and capnography, have allowed these devices to be small and durable enough to be carried into the field, where they can help avoid hyperventilation and injurious ventilation patterns.

  • 21 - Capnography and pulmonary embolism

  • from 1 - Ventilation
  • Edited by J. S. Gravenstein, University of Florida, Michael B. Jaffe, Nikolaus Gravenstein, University of Florida, David A. Paulus, University of Florida
  • Book:
    Capnography
    Published online:
    05 August 2011
    Print publication:
    17 March 2011, pp 195-207

  • Summary

    This chapter focuses on the importance of the potential role of capnography during sleep. It provides a clear definition of the unique changes in ventilation that accompany the sleep state and its various components. With the evolution of significant clinical interest in sleep-related breathing disorders, the use of polysomnography has been expanded to include more detailed assessment of breathing during sleep. Capnometry is the measurement of CO2 concentration in a gas mixture denoted by a continuous waveform display. Sleep serves multiple functions in humans, including biochemical (anabolic hormone secretion, protein synthesis, energy conservation), physiologic, and neurological. It is extensive in its monitoring capacity, but retains significant limitations in its capability to evaluate changes in ventilation and breathing outside of frank obstructive sleep apnea (OSA) for which it was designed. Comprehensive incorporation of capnography into clinical practice has great potential for enhancing the sleep evaluation in many patients.

  • 15 - Capnography in non-invasive positive pressure ventilation

  • from 1 - Ventilation
  • Edited by J. S. Gravenstein, University of Florida, Michael B. Jaffe, Nikolaus Gravenstein, University of Florida, David A. Paulus, University of Florida
  • Book:
    Capnography
    Published online:
    05 August 2011
    Print publication:
    17 March 2011, pp 135-144

  • Summary

    The usually more controlled circumstances of airway management in the operating room (OR) often provide better conditions, better monitoring, and more experienced personnel, particularly when a problem occurs, than is available in other critical care environments or the emergency department. While the detection of CO2 by capnography after completion of a difficult intubation procedure may suggest success, it may more precisely indicate only that the tube tip is somewhere in the respiratory path, although perhaps not exactly where the intubationist desires. A capnography pattern indicating declining CO2 in each subsequent breath over several breaths will help identify esophageal intubation. Unilateral pathophysiologic conditions that cause unilateral hypoventilation or high airway resistances would result in a biphasic waveform. Many techniques to facilitate blind nasal tracheal intubation use the detection of significant exhaled gas flow from a spontaneously breathing patient to indicate the proximity of the tube tip to the glottic opening.

  • 22 - Non-invasive cardiac output via pulmonary blood flow

  • from 1 - Ventilation
  • Edited by J. S. Gravenstein, University of Florida, Michael B. Jaffe, Nikolaus Gravenstein, University of Florida, David A. Paulus, University of Florida
  • Book:
    Capnography
    Published online:
    05 August 2011
    Print publication:
    17 March 2011, pp 208-224

  • Summary

    The term conscious sedation was a source of confusion almost since its introduction by the American Dental Association. In October 2002, the American Dental Association adopted the Guidelines for the Use of Conscious Sedation, Deep Sedation and General Anesthesia for Dentists. Almost as soon as capnography became widely utilized for patients undergoing general anesthesia in an operating room setting, clinicians began seeking a way to monitor exhaled CO2 in unintubated, spontaneously ventilating patients. Pulse oximetry is considered by many clinicians to be an adequate monitor of ventilation during sedation. Essentially all drugs used for sedation are ventilatory depressants. Drug combinations typically have a synergistic, rather than simply additive, effect on ventilation. As evidenced by the disparity in guidelines from different specialty societies, opinions on the value of capnometry vary widely based on the venue and specialty of the sedating physician.

  • 14 - Biofeedback

  • from 1 - Ventilation
  • Edited by J. S. Gravenstein, University of Florida, Michael B. Jaffe, Nikolaus Gravenstein, University of Florida, David A. Paulus, University of Florida
  • Book:
    Capnography
    Published online:
    05 August 2011
    Print publication:
    17 March 2011, pp 127-134

  • Summary

    In the hospital setting, patients in the emergency room and intensive care units are at high risk for complications. This chapter reviews the specific role of capnography in the successful airway management of the hospitalized patient. Initiating airway intubation in the emergency room or in the intensive care unit allows significant opportunity for miscalculations that can take the form of esophageal intubations, delays in securing ventilation due to a difficult airway, and inadequate ventilation due to inappropriate settings. The most frequent cause of a false-positive result occurs when a large amount of expired gas is forced into the esophagus during bag-mask ventilation. As it relates to airway maintenance, continuous capnography provides graphical and numerical assurance of airway patency. During routine intensive care radiographic evaluations, inappropriate enteral tube placement has been identified as often as endotracheal tube malposition.

  • 12 - Conscious sedation

  • from 1 - Ventilation
  • Edited by J. S. Gravenstein, University of Florida, Michael B. Jaffe, Nikolaus Gravenstein, University of Florida, David A. Paulus, University of Florida
  • Book:
    Capnography
    Published online:
    05 August 2011
    Print publication:
    17 March 2011, pp 102-114

  • Summary

    Since gas exchange is a primordial function of the lungs and the conductive airways, respiratory assessment is of paramount importance. Capnography has been utilized in surgical patients for over three decades to confirm tracheal intubation and assess ventilation. Nitrogen washout provides an estimate of functional residual capacity, total lung volume, deadspace volume, and alveolar volume. Clinicians typically utilize exhaled CO2 concentration against time during a respiratory cycle. A number of applications are available in and out of the operating room. Capnography can be used as a continuous monitor of alveolar ventilation in patients with lung disease or hemodynamic instability. Mainstream capnometry appears to provide more accurate PETCO2 than conventional sidestream capnometry during spontaneous breathing in non-intubated patients. In the opinion of some investigators, the technology should be employed in all cases requiring sedation in or out of the operating room.

  • 16 - End-tidal carbon dioxide monitoring in postoperative ventilator weaning

  • from 1 - Ventilation
  • Edited by J. S. Gravenstein, University of Florida, Michael B. Jaffe, Nikolaus Gravenstein, University of Florida, David A. Paulus, University of Florida
  • Book:
    Capnography
    Published online:
    05 August 2011
    Print publication:
    17 March 2011, pp 145-147

  • Summary

    Anesthesiologists monitor their patients' breathing by listening to the lungs or auscultating over the trachea, counting the respiratory rate, watching chest movement and tidal volume, and employing pulse oximetry and capnography. This chapter focuses on issues related to capnography specific to anesthesia and the operating room. Capnography is the best monitor to identify complete disconnection of the breathing circuit. Exhaled tidal volume is a sensitive indicator of leaks and partial disconnects during mechanical ventilation. Capnography will continue to detect expired CO2 as long as the patient's exhaled tidal volume passes sidestream or mainstream sampling ports. Patients with chronic obstructive pulmonary disease or asthma exhibit typical capnograms with upsloping expired values brought about by the slow emptying of partially obstructed segments of the lungs. Intermittent PaCO2 determination has been used as a routine parameter for acid-base management during cardiopulmonary bypass (CPB).

  • 29 - Carbon dioxide pathophysiology

  • from 1 - Ventilation
  • Edited by J. S. Gravenstein, University of Florida, Michael B. Jaffe, Nikolaus Gravenstein, University of Florida, David A. Paulus, University of Florida
  • Book:
    Capnography
    Published online:
    05 August 2011
    Print publication:
    17 March 2011, pp 283-294

  • Summary

    This chapter highlights the role of capnography as a monitoring tool with the different adjuncts to mechanical ventilation that are currently used in critically ill patients. The application of positive end-expiratory pressure (PEEP) is used to increase lung volume and improve oxygenation in patients with acute lung injury (ALI). Studies of unilateral lung injury demonstrate that the consolidated lung regions do not expand to total lung capacity during inflation. Tracheal gas insufflation (TGI) is an adjunct to mechanical ventilation that allows ventilation with small tidal volumes while CO2 is satisfactorily eliminated. High-frequency ventilation (HFV) techniques have three essential elements in common: a high-pressure flow generator, a valve for flow interruption, and a circuit for connection to the patient. Measurement of deadspace fraction early in the course of acute respiratory failure may provide clinicians important physiologic and prognostic information.

  • 32 - Capnographic measures

  • from 1 - Ventilation
  • Edited by J. S. Gravenstein, University of Florida, Michael B. Jaffe, Nikolaus Gravenstein, University of Florida, David A. Paulus, University of Florida
  • Book:
    Capnography
    Published online:
    05 August 2011
    Print publication:
    17 March 2011, pp 329-339

  • Summary

    This chapter describes the pathophysiologic basis and use of capnography in the detection of pulmonary embolism (PE) from a variety of causes. Pulmonary embolism results in an increase in respiratory deadspace, specifically alveolar deadspace, which can be determined with parameters obtained with capnography. Pulmonary embolism results in an occlusion or limitation of flow in the pulmonary vasculature to respiratory units. Pulmonary embolism effects an increase in the physiologic deadspace by increasing alveolar deadspace, a component of the physiologic deadspace. FDlate is determined from fitting the phase III slope portion of the volumetric capnogram. The ability of volumetric capnography to track the resolution of pulmonary emboli with thrombolytic therapy has also been investigated. Evaluation of patients with various parameters derived from capnography holds promise for early bedside non-invasive detection of embolism, thereby allowing prompt and effective therapy.

  • A comparative evaluation of capnometry versus pulse oximetry during procedural sedation and analgesia on room air

  • Marco L.A. Sivilotti, David W. Messenger, Janet van Vlymen, Paul E. Dungey, Heather E. Murray
  • Journal:
    Canadian Journal of Emergency Medicine / Volume 12 / Issue 5 / September 2010
    Published online by Cambridge University Press:
    21 May 2015, pp. 397-404
    Print publication:
    September 2010
    • Article
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  • Objective:

    Important questions remain regarding how best to monitor patients during procedural sedation and analgesia (PSA). Capnometry can detect hypoventilation and apnea, yet it is rarely used in emergency patients. Even the routine practice of performing preoxygenation in low-risk patients is controversial, as supplementary oxygen can delay the detection of respiratory depression by pulse oximetry. The purpose of this study was to determine whether the capnometer or the pulse oximeter would first detect respiratory events in adults breathing room air.

    Methods:

    During a randomized clinical trial comparing fentanyl with low-dose ketamine for PSA with titrated propofol, patients were monitored using pulse oximetry and continuous oral–nasal sampled capnography. Supplemental oxygen was administered only for oxygen desaturation. Sedating physicians identified prespecified respiratory events, including hypoventilation (end-tidal carbon dioxide > 50 mm Hg, rise of 10 mm Hg from baseline or loss of waveform) and oxygen desaturation (pulse oximetry < 92%). These events and their timing were corroborated by memory data retrieved from the monitors.

    Results:

    Of 63 patients enrolled, 57% (36) developed brief oxygen desaturation at some point during the sedation. All responded to oxygen, stimulation or interruption of propofol. Measurements of end-tidal carbon dioxide varied substantially between and within patients before study intervention. Hypoventilation (19 patients, 30%) was only weakly associated with oxygen desaturation (crude odds ratio 1.4 [95% confidence interval 0.47 to 4.3]), and preceded oxygen desaturation in none of the 12 patients in whom both events occurred (median lag 1:50 m:ss [interquartile range 0:01 to 3:24 m:ss]).

    Conclusion:

    During PSA in adults breathing room air, desaturation detectable by pulse oximeter usually occurs before overt changes in capnometry are identified.

  • Modified nasal cannula for simultaneous oxygen delivery and end-tidal CO2 monitoring during spontaneous breathing

  • F. Yanagidate, S. Dohi
  • Journal:
    European Journal of Anaesthesiology / Volume 23 / Issue 3 / March 2006
    Published online by Cambridge University Press:
    24 January 2006, pp. 257-260
    Print publication:
    March 2006

  • Summary

    Background and objectives: Supplemental oxygen is commonly given via nasal cannulae in spontaneously breathing patients. Our modified nasal cannula with a clamp between the nasal prongs can provide O2 via one nostril and CO2 can be sampled through the other one. We have studied whether this cannula can provide oxygenation similar to a standard cannula without affecting end-tidal CO2 monitoring. Methods: Eighty-six patients were studied during spinal anaesthesia and sedation. In 15 patients, arterial blood was sampled while O2 was delivered at flow rates of 0, 2 and 4L min−1, with or without clamping between the prongs of our modified nasal cannula. In the remaining 71 patients, arterial O2 was measured while using our modified nasal cannula with the clamp applied. End-tidal CO2 was recorded on a capnograph and the correlation between end-tidal and arterial values with our modified nasal cannula was investigated. Results: No end-tidal CO2 waveforms were found with oxygen flow greater than 2L min−1 without clamping between the prongs. With clamping there was a significant correlation (r = 0.83) between arterial and end-tidal CO2. A Bland–Altman analysis revealed a bias of 0.49 kPa with precision of ±0.76 kPa. Arterial oxygenation was not affected by our modified nasal prongs with clamp as compared to the standard cannula. Conclusion: Our modified nasal cannula can provide continuous monitoring of end-tidal CO2 without affecting oxygen delivery in sedated, spontaneously breathing patients.

  • Comparison of a Colorimetric End-Tidal CO2 Detector and an Esophageal Aspiration Device for Verifying Endotracheal Tube Placement in the Prehospital Setting: A Six-Month Experience

  • Richard J. Schaller, J. Stephen Huff, Allan Zahn
  • Journal:
    Prehospital and Disaster Medicine / Volume 12 / Issue 1 / March 1997
    Published online by Cambridge University Press:
    28 June 2012, pp. 57-63
    Print publication:
    March 1997
  • Introduction:

    Hand held, colorimetric, end-tidal CO2 detector devices are being used to verify correct endotracheal tube (ETT) placement. The accuracy of these devices has been questioned in situations of cardiac arrest. The use of the esophageal detector device (EDD) is an easy alternative for detection of ETT placement, and may be more accurate in situations of cardiac arrest.

    Hypothesis:

    The use of the esophageal aspiration device in comparison with a colorimetric end-tidal CO2 detector is more accurate in detecting proper ETT placement and easier to use in the prehospital setting than is the colorimetric end-tidal CO2 detection device.

    Methods:

    This was a prospective alternating weeks, 6-month study in a prehospital setting. Participants included all patients older than 18 years who were intubated by the Portsmouth, Virginia Emergency Medical Services (EMS) personnel from 01 July 1993 through 31 December 1993. The aspiration device used, also known as an esophageal detector device (EDD), was a 60 ml, luer-lock syringe attached to a 15 mm ETT adapter. Its efficacy was compared with an already accepted method of ETT position detection, the colorimetric endtidal CO2 detector. Each device was used on alternating weeks, and correct ETT placement was determined by the receiving emergency department physician using standard techniques. Chi-square analysis and Fisher's Exact test were used to compare parameters, time of device use, and ease of use. Sensitivity and specificity were calculated, and provider preference was assessed using a survey instrument administered following completion of the study.

    Results:

    There were 49 patients who met the inclusion criteria, but six were excluded because of situational circumstances rendering use of the device a possible compromise of patient care. Twenty-five patients were in the EDD group, and 18 were in the endtidal CO2 detector group. There was no statistically significant difference detected between groups for the gender ratio, underlying condition, CPR in progress, perceived difficulty of intubation, or percentage of nasotracheal intubation. The EDD was significantly easier to use (p<0.005). There was no statistically significant difference in time required for use of end-tidal CO2 detector device versus the EDD. The sensitivity and specificity for correct tracheal placement using the EDD was 100%, and the sensitivity for correct tracheal placement using the end-tidal CO2 detector device was 78%. Use of the EDD was preferred over use of the end-tidal CO2 detector device by 75% of participating EMS providers. One case of nasotracheal intubation with an ETT placement above the cords raised the question of accuracy of this device in situations where direct visualization is not utilized.

    Conclusion:

    The EDD was accurate in all cases of orotracheal intubation, and was easier to use than was end-tidal CO2 detector device. It was preferred by 75% of participating EMS providers. In cases in which the ETT may be above the vocal cords, caution must be used with interpreting the results obtained by use of the EDD.