Department of Anaesthesiology and Intensive Care Medicine, Federal Armed Forces Medical Centre Ulm, D-89070 Ulm, Germany
Corresponding author. E-mail: matthias.helm@extern.uni-ulm.de
Accepted for publication: November 8, 2002
![]() |
Abstract |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Methods. Ninety-seven major trauma victims who underwent tracheal intubation in the field and controlled ventilation of the lungs during prehospital treatment by a Helicopter Emergency Medical Service were assigned randomly to one of two groups: (1) monitor group (n=57) and (2) monitor-blind group (n=40), according to whether the anaesthetist could or could not see an attached capnograph screen. In the monitor-blind group ventilation was set by using a tidal-volume of 10 ml kg1 estimated body weight and an age-appropriate ventilatory frequency. In the monitor group, ventilation was adjusted to achieve target end-tidal carbon dioxide values determined by the physiological state of the trauma victim. Arterial blood gases were measured upon hospital admission while maintaining the ventilation initiated in the field and the PaCO2 value obtained was used as the determinant of the adequacy of prehospital ventilation.
Results. The incidence of normoventilation was significantly higher (63.2 vs 20%; P<0.0001) and the incidence of hypoventilation upon hospital admission was significantly lower (5.3 vs 37.5%; P<0.0001) in the monitor group; patients with severe head and chest trauma and haemodynamically unstable patients and those with a high injury severity score were significantly more likely to be normoventilated upon hospital admission in the monitor group than in the monitor-blind group.
Conclusions. The data support the routine use of prehospital capnographic monitoring using target end-tidal carbon dioxide values adapted to the physiological state of the patient in major trauma victims requiring tracheal intubation in the field.
Br J Anaesth 2003; 90: 32732
Keywords: carbon dioxide; complications, trauma; monitoring, carbon dioxide; ventilation, artificial
![]() |
Introduction |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
The purpose of this study was to compare the effect of ventilation adjusted to achieve an end-tidal carbon dioxide determined according to the clinical condition of each patient with ventilation determined according to the weight of the patient on admission PaCO2.
![]() |
Patients and methods |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Stastical methods
All values in the tables and figures are expressed as means (SD) unless otherwise indicated. Each variable was tested for differences between groups by Students t-test or 2 analysis where appropriate. A value of P<0.05 was considered to be statistically significant. Statistical analysis was performed using specialized statistical software (Almo© version 5.0; K. Holm, University of Graz, Austria).
![]() |
Results |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
|
|
|
|
|
![]() |
Discussion |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Monitoring of end-tidal carbon dioxide has become standard in the prehospital management and air transfer of severely traumatized patients. Capnography applied at the scene of an accident assists confirmation of tracheal intubation, diagnosis of circuit disconnection and assessment of cardiopulmonary resuscitation.31 Furthermore, on-scene capnography has been proposed as an alternative to intermittent PaCO2 measurements for monitoring the adequacy of prehospital ventilation in major trauma victims.5 6 11 12 31 The problem of capnography in this context is that it is not solely a measurement of the respiratory function and capnograms must be interpreted in conjunction with other clinical findings.32 Some authors11 13 33 34 doubt that capnography may be of benefit in calculating prehospital ventilation. Böbel and colleagues13 concluded in their study that calculation of prehospital ventilation by end-tidal carbon dioxide monitoring seems to be problematic because of unknown arterial end-tidal carbon dioxide tension difference in the prehospital setting. In major trauma victims, severe chest trauma, hypotension and heavy blood loss were found to reduce end-tidal carbon dioxide and increase P(a-E')CO2 differences to more than 10 mm Hg.9 13 15 16 18 36 37 These increased P(a-E')CO2 differences are thought to be largely because of an increased alveolar dead space, which is probably caused by decreased alveolar perfusion resulting from a reduced cardiac output and/or maldistribution or occlusion of portions of the pulmonary blood flow.9
Our study demonstrated that prehospital ventilation calculated according to the physiological state of the trauma victim and controlled by capnography, facilitates tighter control of PaCO2. The incidence of normoventilation was significantly increased (63.2 vs 20.0%; P<0.0001) while the incidence of hypoventilation upon hospital admission was significantly reduced (5.3 vs 37.5%; P<0.0001) in the monitor group compared with the monitor-blind group, whereas the incidence of hyperventilation upon hospital admission was not reduced in the monitor group. This result may be explained by using a PaCO2 value of 35 mm Hg both as the target in the monitor group and the cut-off value for classifying the outcome as normo- or hyperventilation. Palmon and colleagues12 found similar results in their study on the in-hospital transport of intubated patients from the operating room to the intensive care unit (ICU) and from the ICU for examinations in the radiology department; they conclude that using an end-tidal carbon dioxide monitor for transport helps guide ventilation of patients who require tight control of PaCO2.
The prehospital phase seems to be the most critical interval in determining the ultimate outcome after traumatic brain injury. Therefore, especially patients with associated severe head trauma may profit from a close control of PaCO2. Schüttler and colleagues4 have shown in their study on the quality of prehospital management of severe head injury that mortality is significantly reduced within a group of prehospitally intubated and ventilated patients in those with good compared with those with poor respiratory therapy (25 vs 61%). The significant increase of intended normoventilation in the population of patients with associated severe head injury (AIS>3) in our study in the monitor group compared with the monitor-blind group (57.5 vs 12.9%; P<0.001) is therefore of major importance.
Based upon the results of a number of studies,13 1518 patients in the monitor group of our study with associated severe chest trauma and/or haemodynamic instability were ventilated to achieve an end-tidal carbon dioxide in the range of 2530 mm Hg; both subpopulations were significantly more patients meeting these criteria were normoventilated upon hospital admission in the monitor group than in the monitor-blind group (Fig. 3). Therefore, we have shown that it is possible without knowledge of P(a-E')CO2 to ventilate trauma victims, including subpopulations with probable increased P(a-E')CO2, more tightly in the prehospital setting than has been possible before.
In conclusion, the data of our study support the routine use of an end-tidal carbon dioxide controlled prehospital ventilation in trauma victims, which considers the physiological state of the patient. The protocol used in this study seems to be simple, practicable and effective for usage in the prehospital setting.
![]() |
References |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
2 Nolan JP, Paar MJA. Aspects of resuscitation in trauma. Br J Anaesth 1997; 79: 22640
3 Trupka A, Waydhas C, Nast-Kolb D, et al. Early intubation in severely injured patients. Eur J Emerg Med 1994; 1: 18[Medline]
4 Schüttler J, Schmitz B, Bartsch AC, et al. Efficacy of advanced trauma life support in patients with brain injury and multiple trauma. A contribution to quality assurance in emergency medicine (German). Anaesthesist 1995; 44: 8508[CrossRef][ISI][Medline]
5 Helm M, Hauke J, Sauermüller G, et al. About the quality of prehospital emergency ventilationa prospective study in trauma patients (German). Unfallchirurg 1999; 102: 34753[CrossRef][ISI][Medline]
6 Helm M, Hauke J, Lampl L. About the quality of prehospital emergency ventilationa prospective study in patients with severe head injury. Br J Anaesth 2002; 88: 3459
7 Kuhnigk H, Lingg V, Sefrin P, et al. Kalkulierte Beatmung bei PolytraumatisiertenZielsetzung des Notarztes und Ergebnisse bei Klinikaufnahme (German). Anaesthesiol Intensivmed Notfallmed Schmerzther 1998; 33/3: 190
8 Kehrberger E, Hörtling H. Blutgasanalysen nach präklinischer kontrollierter Beatmung durch den Notarzt. Der Notarzt 1989; 5: 1404
9 Russel GB, Graybeal JM. Reliability of the arterial to end-tidal carbon dioxide gradient in mechanically ventilated patients with multisystem trauma. J Trauma 1994; 36: 31722[ISI][Medline]
10 Santos LJ, Varon J, Pic-Aluas L, et al. Practical use of end-tidal carbon dioxide monitoring in the emergency department. J Emerg Med 1994; 12: 63344[CrossRef][Medline]
11 Hoffmann RA, Krieger BP, Kramer MR, et al. End-tidal dioxide in critically ill patients during changes in mechanical ventilation. Am Rev Respir Dis 1989; 140: 12658[ISI][Medline]
12 Palmon SC, Liu M, Moore LE, et al. Capnography facilitates tight control of ventilation during transport. Crit Care Med 1996; 24: 60811[CrossRef][ISI][Medline]
13 Böbel M, Graf S, Geitner K, et al. Bestimmung arterio-endexspiratorischer CO2-Differenzen in der präklinischen Versorgungsphase. Der Notarzt 1997; 13: 12631
14 Schou J. Endotracheal intubation and ventilation. In: Schou J, ed. Prehospital Emergency Medicine. Amsterdam: Harwood Academic Publishers, 1992; 7991
15 Ensle G, Altemeyer KH. The arterial to end expiratory CO2 difference with ventilated patients in emergency medicine (German). Notfall Rettungsmedizin 1998; 6: 34754
16 Whitesell R, Asiddao C, Gollmann D, et al. Relationship between arterial and peak expired carbon dioxide pressure during anethesia and factors influencing the difference. Anesth Analg 1981; 60: 50812[Abstract]
17 Rückoldt H, Marx G, Leuwer M, et al. Pulsoxymetrie und Kapnometrie bei Intensivtransporten: kombinierter Einsatz verringert das Transportrisiko. Anaesthesiol Intensivmed Notfallmed Schmerzther 1998; 32: 3236
18 Helm M, Hauke J, Lampl L, et al. Arterial to end-tidal carbon dioxide gradient and Horovitz-quotient of value in diagnostic blunt chest trauma? Br J Anaesth 1995; 74: 127
19 Helm M, Hauke J, Esser M, et al. Prehospital diagnosis in blunt chest trauma: efficacy of continuous pulse oximetric monitoring (German). Chirurg 1997; 68: 60612[CrossRef][ISI][Medline]
20 Baker SP, ONeill B, Haddon W. The Injury Severity Score: a method for describing patients with multiple injuries and evaluating emergency care. J Trauma 1974; 14: 18796[ISI][Medline]
21 Arbeitsgemeinschaft Scoring der Deutschen Gesellschaft für Unfallchirurgie (DGU) Das Traumaregister der Deutschen Gesellschaft für Unfallchirurgie. Unfallchirurg 1994; 97: 2307[ISI][Medline]
22 Miller JD, Sweet RC, Narayan R, et al. Early insults of the injured brain. JAMA 1978; 240: 43942[Abstract]
23 Gildenberg PL, Makela M. The effect of early intubation and ventilation on outcome following head trauma. In: Winn WR, Rimel R, Jane JA, eds. Recent Advances in Neurotrauma. New York: Raven Press, 1985; 7990
24 Kehrberger E, Hörtling H. Blutgasanalysen nach präklinischer kontrollierter Beatmung durch den Notarzt. Der Notarzt 1990; 5: 24
25 Kuhnigk H, Zischler K. Narkose im Rettungsdienst. In: Sefrin P, ed. Beatmung im Rettungsdienst. Munich: Zuckschwerdt, 1995; 8995
26 Gervais HW, Eberele B, Konietzke D, et al. Comparison of blood gases of ventilated patients during transport. Crit Care Med 1987; 15/8: 7613
27 Carden E, Friedman D. Further studies of manually operated self-inflating resuscitation bags. Anesth Analg 1977; 56: 2026[Abstract]
28 Rossi R, Lotz P, Keller A. Charakteristika von Geräten zur Beatmung von Patienten am Notfallort und auf dem transport. Anästhesist 1989; 39 (Suppl 1): 142
29 Rossi R, Rockemann M, Keller A. Einsatz von Notfallrespiratoren beim innerklinischen transport. Notfallmedizin 1993; 19: 269
30 Morley AP. Prehospital monitoring of trauma patients: experience of an emergency helicopter medical service. Br J Anaesth 1996; 76: 72630
31 Napolitano LM: Capnography in critical care: accurate assessment of ARDS therapy? Crit Care Med 1999; 27/5: 8623[CrossRef]
32 Prause G, Hetz H, Lauda P, et al. A comparison of the end-tidal CO2 documented by capnometry and the arterial pCO2 in emergency patients. Resuscitation 1997; 35: 1458[CrossRef][ISI][Medline]
33 Wahba RWM, Tessler MJ. Misleading end-tidal CO2 tensions. Can J Anaesth 1996; 43: 8626[Abstract]
34 Wilson R, Tyburski JG, Kubinec SM, et al. Intraoperative end-tidal carbon dioxide levels and derived calculations correlated with outcome in trauma patients. J Trauma 1996; 41: 60611[ISI][Medline]
35 Lenz G, Klöss T, Schorer R. Grundlagen und Anwendung der Kapnometrie. Anästhesiol Intensivmed 1985; 26: 13341
36 Craig GR, Randalls PB. Analysis of arterial to end-tidal carbon dioxide gradients in ventilated trauma patients. J Trauma 1993; 35: 331
37 Prough DS, Lang J. Therapy of patients with head injuries: key parameters for management. J Trauma 1997; 42/5: 1017