Hyperventilation in traumatic brain injury patients: inconsistency between consensus guidelines and clinical practice

Hyperventilation During Manual Ventilation Can Be Reduced Using a Novel Ventilator but Not With Education Interventions

INTRODUCTION

Traumatic brain injury (TBI) is the leading cause of combat casualties in modern war with an estimated 20% of casualties experiencing head injury. Since the release of the Brain Trauma Foundation's Guidelines for the Management of Severe Traumatic Brain Injury in 1995, recommendations for management of TBI have included the avoidance of routine hyperventilation. However, both published and anecdotal data suggest that many patients with TBI are inappropriately ventilated during transport, thereby increasing the risk of morbidity and mortality from secondary brain injury.

MATERIALS AND METHODS

Enlisted Air Force personnel with prior emergency medical technician training completing a 3-week trauma course were evaluated on their ability to provide manual ventilation. Participants provided manual ventilation using either an in-situ endotracheal tube (ETT) or standard face mask on a standardized simulated patient manikin with TBI on the first and last days of the course. Manual ventilation was provided via a standard manual ventilator and a novel manual ventilator designed to limit tidal volume (VT) and respiratory rate (RR). Participants were given didactic and hands-on training on the third day of the course. Half of the participants were given simulator feedback during the hands-on training. All students provided 2 minutes of manual ventilation with each respirator. Data were collected on the breath-to-breath RR, VT, and peak airway pressures generated by the participant for each trial and were averaged for each trial. A minute ventilation (MV) was then derived from the calculated RR and VT.

RESULTS

One hundred fifty-six personnel in the trauma course were evaluated in this study. Significant differences were found in the participant's performance with manual ventilation with the novel compared to the traditional ventilator. Before training, MV with the novel ventilator was less than with the traditional ventilator by 2.1 ± 0.4 L/min (P = .0003) and 1.6 ± 0.5 L/min (P = .0489) via ETT and face mask, respectively. This effect persisted after training with a difference between the devices of 1.8 ± 0.4 L/min (P = .0069) via ETT. Both traditional education interventions (didactics with hands-on training) and simulator-based feedback did not make a significant difference in participant's performance in delivering MV.

CONCLUSIONS

The use of a novel ventilator that limits RR and VT may be useful in preventing hyperventilation in TBI patients. Didactic education and simulator-based feedback training may not have significant impact on improving ventilation practices in prehospital providers.

Association of Flow Rate of Prehospital Oxygen Administration and Clinical Outcomes in Severe Traumatic Brain Injury

The goal of this study was to investigate the association of prehospital oxygen administration flow with clinical outcome in severe traumatic brain injury (TBI) patients. This was a cross-sectional observational study using an emergency medical services-assessed severe trauma database in South Korea. The sample included adult patients with severe blunt TBI without hypoxia who were treated by EMS providers in 2013 and 2015. Main exposure was prehospital oxygen administration flow rate (no oxygen, low-flow 1~5, mid-flow 6~14, high-flow 15 L/min). Primary outcome was in-hospital mortality. A total of 1842 patients with severe TBI were included. The number of patients with no oxygen, low-flow oxygen, mid-flow oxygen, high-flow oxygen was 244, 573, 607, and 418, respectively. Mortality of each group was 34.8%, 32.3%, 39.9%, and 41.1%, respectively. Compared with the no-oxygen group, adjusted odds (95% CI) for mortality in the low-, mid-, and high-flow oxygen groups were 0.86 (0.62–1.20), 1.15 (0.83–1.60), and 1.21 (0.83–1.73), respectively. In the interaction analysis, low-flow oxygen showed lower mortality when prehospital saturation was 94–98% (adjusted odds ratio (AOR): 0.80 (0.67–0.95)) and ≥99% (AOR: 0.69 (0.53–0.91)). High-flow oxygen showed higher mortality when prehospital oxygen saturation was ≥99% (AOR: 1.33 (1.01~1.74)). Prehospital low-flow oxygen administration was associated with lower in-hospital mortality compared with the no-oxygen group. High-flow administration showed higher mortality.

Acute Management of Traumatic Brain Injury

Traumatic brain injury (TBI) is a leading cause of death and disability in patients with trauma. Management strategies must focus on preventing secondary injury by avoiding hypotension and hypoxia and maintaining appropriate cerebral perfusion pressure (CPP), which is a surrogate for cerebral blood flow. CPP can be maintained by increasing mean arterial pressure, decreasing intracranial pressure, or both. The goal should be euvolemia and avoidance of hypotension. Other factors that deserve important consideration in the acute management of patients with TBI are venous thromboembolism, stress ulcer, and seizure prophylaxis, as well as nutritional and metabolic optimization.

Evaluation of the impact of implementing the emergency medical services traumatic brain injury guidelines in Arizona: the Excellence in Prehospital Injury Care (EPIC) study methodology

Traumatic brain injury (TBI) exacts a great toll on society. Fortunately, there is growing evidence that the management of TBI in the early minutes after injury may significantly reduce morbidity and mortality. In response, evidence-based prehospital and in-hospital TBI treatment guidelines have been established by authoritative bodies. However, no large studies have yet evaluated the effectiveness of implementing these guidelines in the prehospital setting. This article describes the background, design, implementation, emergency medical services (EMS) treatment protocols, and statistical analysis of a prospective, controlled (before/after), statewide study designed to evaluate the effect of implementing the EMS TBI guidelines-the Excellence in Prehospital Injury Care (EPIC) study (NIH/NINDS R01NS071049, "EPIC"; and 3R01NS071049-S1, "EPIC4Kids"). The specific aim of the study is to test the hypothesis that statewide implementation of the international adult and pediatric EMS TBI guidelines will significantly reduce mortality and improve nonmortality outcomes in patients with moderate or severe TBI. Furthermore, it will specifically evaluate the effect of guideline implementation on outcomes in the subgroup of patients who are intubated in the field. Over the course of the entire study (~9 years), it is estimated that approximately 25,000 patients will be enrolled.

Physician-based emergency medical service deployment characteristics in severe traumatic brain injury: a Dutch multicenter study

INTRODUCTION

Prehospital guidelines advise advanced life support in all patients with severe traumatic brain injury (TBI). In the Netherlands, it is recommended that prehospital advanced life support is particularly provided by a physician-based helicopter emergency medical service (P-HEMS) in addition to paramedic care (EMS). Previous studies have however shown that a substantial part of severe TBI patients is exclusively treated by an EMS team. In order to better understand this phenomenon, we evaluated P-HEMS deployment characteristics in severe TBI in a multicenter setting.

METHODS

The database included patient demographics, prehospital and injury severity parameters and determinants of EMS or EMS/P-HEMS dispatch in 334 patients with severe TBI admitted to level 1 trauma centres in the Netherlands.

RESULTS

P-HEMS was deployed in 62% of patients with severe TBI. Patients treated by the P-HEMS had a higher injury severity score (29 (20-38)) vs. (25 (16-30); P<0.001), more frequently required blood product transfusions (41% vs. 29%; P=0.03) and recurrently suffered from TBI with extracranial injuries (33% vs. 6%; P<0.001) than patients solely treated by an EMS. The prehospital endotracheal intubation rate was higher in the P-HEMS group in isolated TBI (93% vs. 19%; P<0.001) or TBI with extracranial injuries (96% vs. 43%; P<0.001) compared to the EMS group. In the EMS group, more patients were secondary referred to a level 1 trauma centre (32% vs. 4%; P<0.001 vs. P-HEMS). Despite higher injury severity levels in P-HEMS patients, 6-month mortality rates were similar among groups, irrespective of the presence of extracranial injuries in addition to TBI. Deployment of P-HEMS estimated 52% and 72% (P<0.001) in urban and rural regions, respectively, with comparable endotracheal intubation rates among regions.

CONCLUSIONS

This study shows that a physician-based HEMS was more frequently deployed in patients with severe TBI in the presence of extracranial injuries, and in rural trauma regions. Treatment of severe TBI patients by a paramedic EMS only was associated with a higher incidence of secondary referrals to a level I trauma centre. Our data support adjustment of local prehospital guidelines for patients with severe TBI to the geographical context.

Adherence to guidelines and protocols in the prehospital and emergency care setting: a systematic review

A gap between guidelines or protocols and clinical practice often exists, which may result in patients not receiving appropriate care. Therefore, the objectives of this systematic review were (1) to give an overview of professionals' adherence to (inter)national guidelines and protocols in the emergency medical dispatch, prehospital and emergency department (ED) settings, and (2) to explore which factors influencing adherence were described in studies reporting on adherence. PubMed (including MEDLINE), CINAHL, EMBASE and the Cochrane database for systematic reviews were systematically searched. Reference lists of included studies were also searched for eligible studies. Identified articles were screened on title, abstract and year of publication (≥1990) and were included when reporting on adherence in the eligible settings. Following the initial selection, articles were screened full text and included if they concerned adherence to a (inter)national guideline or protocol, and if the time interval between data collection and publication date was <10 years. Finally, articles were assessed on reporting quality. Each step was undertaken by two independent researchers. Thirty-five articles met the criteria, none of these addressed the emergency medical dispatch setting or protocols. Median adherence ranged from 7.8-95% in the prehospital setting, and from 0-98% in the ED setting. In the prehospital setting, recommendations on monitoring came with higher median adherence percentages than treatment recommendations. For both settings, cardiology treatment recommendations came with relatively low median adherence percentages. Eight studies identified patient and organisational factors influencing adherence. The results showed that professionals' adherence to (inter)national prehospital and emergency department guidelines shows a wide variation, while adherence in the emergency medical dispatch setting is not reported. As insight in influencing factors for adherence in the emergency care settings is minimal, future research should identify such factors to allow the development of strategies to improve adherence and thus improve quality of care.

Helicopter EMS: Research Endpoints and Potential Benefits

Patients, EMS systems, and healthcare regions benefit from Helicopter EMS (HEMS) utilization. This article discusses these benefits in terms of specific endpoints utilized in research projects. The endpoint of interest, be it primary, secondary, or surrogate, is important to understand in the deployment of HEMS resources or in planning further HEMS outcomes research. The most important outcomes are those which show potential benefits to the patients, such as functional survival, pain relief, and earlier ALS care. Case reports are also important "outcomes" publications. The benefits of HEMS in the rural setting is the ability to provide timely access to Level I or Level II trauma centers and in nontrauma, interfacility transport of cardiac, stroke, and even sepsis patients. Many HEMS crews have pharmacologic and procedural capabilities that bring a different level of care to a trauma scene or small referring hospital, especially in the rural setting. Regional healthcare and EMS system's benefit from HEMS by their capability to extend the advanced level of care throughout a region, provide a "backup" for areas with limited ALS coverage, minimize transport times, make available direct transport to specialized centers, and offer flexibility of transport in overloaded hospital systems.

Inappropriate prehospital ventilation in severe traumatic brain injury increases in-hospital mortality

In the setting of acute brainstem herniation in traumatic brain injury (TBI), the use of hyperventilation to reduce intracranial pressure may be life-saving. However, undue use of hyperventilation is thought to increase the incidence of secondary brain injury through direct reduction of cerebral blood flow. This is a retrospective review determining the effect of prehospital hyperventilation on in-hospital mortality following severe TBI. All trauma patients admitted directly to a single level 1 trauma center from January 2000 to January 2007 with an initial Glasgow Coma Scale (GCS) score <or=8 were included in the study (n = 77). Patients without documented or with late (>20 min) arterial blood gas at presentation (n = 12) were excluded from the study. The remaining population (n = 65) was sorted into three groups based on the initial partial pressure of carbon dioxide: hypocarbic (Pco(2) < 35 mm Hg), normocarbic (Pco(2) 35-45 mm Hg), and hypercarbic (Pco(2) > 45 mm Hg). Outcome was based on mortality during hospital admission. Survival was found to be related to admission Pco(2) in head trauma patients requiring intubation (p = 0.045). Patients with normocarbia on presenting arterial blood gas testing had in-hospital mortality of 15%, significantly improved over patients presenting with hypocarbia (in-hospital mortality 77%) or hypercarbia (in-hospital mortality 61%). Although there are many reports of the negative impact of prophylactic hyperventilation following severe TBI, this modality is frequently utilized in the prehospital setting. Our results suggest that abnormal Pco(2) on presentation after severe head trauma is correlated with increased in-hospital mortality. We advocate normoventilation in the prehospital setting.

Smaller self-inflating bags produce greater guideline consistent ventilation in simulated cardiopulmonary resuscitation

Background

Suboptimal bag ventilation in cardiopulmonary resuscitation (CPR) has demonstrated detrimental physiological outcomes for cardiac arrest patients. In light of recent guideline changes for resuscitation, there is a need to identify the efficacy of bag ventilation by prehospital care providers. The objective of this study was to evaluate bag ventilation in relation to operator ability to achieve guideline consistent ventilation rate, tidal volume and minute volume when using two different capacity self-inflating bags in an undergraduate paramedic cohort.

Methods

An experimental study using a mechanical lung model and a simulated adult cardiac arrest to assess the ventilation ability of third year Monash University undergraduate paramedic students. Participants were instructed to ventilate using 1600 ml and 1000 ml bags for a length of two minutes at the correct rate and tidal volume for a patient undergoing CPR with an advanced airway. Ventilation rate and tidal volume were recorded using an analogue scale with mean values calculated. Ethics approval was granted.

Results

Suboptimal ventilation with the use of conventional 1600 ml bag was common, with 77% and 97% of participants unable to achieve guideline consistent ventilation rates and tidal volumes respectively. Reduced levels of suboptimal ventilation arouse from the use of the smaller bag with a 27% reduction in suboptimal tidal volumes (p = 0.015) and 23% reduction in suboptimal minute volumes (p = 0.045).

Conclusion

Smaller self-inflating bags reduce the incidence of suboptimal tidal volumes and minute volumes and produce greater guideline consistent results for cardiac arrest patients.

The use of hyperventilation therapy after traumatic brain injury in Europe: an analysis of the BrainIT database

OBJECTIVE

To assess the use of hyperventilation and the adherence to Brain Trauma Foundation-Guidelines (BTF-G) after traumatic brain injury (TBI).

SETTING

Twenty-two European centers are participating in the BrainIT initiative.

DESIGN

Retrospective analysis of monitoring data.

PATIENTS AND PARTICIPANTS

One hundred and fifty-one patients with a known time of trauma and at least one recorded arterial blood-gas (ABG) analysis.

MEASUREMENTS AND RESULTS

A total number of 7,703 ABGs, representing 2,269 ventilation episodes (VE) were included in the analysis. Related minute-by-minute ICP data were taken from a 30 min time window around each ABG collection. Data are given as mean with standard deviation. (1) Patients without elevated intracranial pressure (ICP) (< 20 mmHg) manifested a statistically significant higher P(a)CO(2) (36 +/- 5.7 mmHg) in comparison to patients with elevated ICP (> or = 20 mmHg; P(a)CO(2): 34 +/- 5.4 mmHg, P < 0.001). (2) Intensified forced hyperventilation (P(a)CO(2) < or = 25 mmHg) in the absence of elevated ICP was found in only 49 VE (2%). (3) Early prophylactic hyperventilation (< 24 h after TBI; P(a)CO(2) < or = 35 mmHg, ICP < 20 mmHg) was used in 1,224 VE (54%). (4) During forced hyperventilation (P(a)CO(2) < or = 30 mmHg), simultaneous monitoring of brain tissue pO(2) or S(jv)O(2) was used in only 204 VE (9%).

CONCLUSION

While overall adherence to current BTF-G seems to be the rule, its recommendations on early prophylactic hyperventilation as well as the use of additional cerebral oxygenation monitoring during forced hyperventilation are not followed in this sample of European TBI centers.

DESCRIPTOR

Neurotrauma.

Early ventilation in traumatic brain injury

While airway and ventilatory compromise are significant concerns following traumatic brain injury (TBI), there is little data supporting an aggressive approach to airway management by prehospital personnel, and a growing number of reports suggesting an association between early intubation and increased mortality. Recent clinical and experimental data suggest that hyperventilation is an important contributor to these adverse outcomes in TBI patients. Various mechanisms appear to be responsible for the worsened outcomes, including hemodynamic, cerebrovascular, immunologic and cellular effects. Here, relevant experimental and clinical data regarding the impact of ventilation on TBI are reviewed. In addition, experimental data regarding potential mechanisms for the adverse effects of hyperventilation and hypocapnia on the injured brain are presented. Finally, the limited data regarding the impact of hypoventilation and hypercapnia on outcome from TBI are discussed.

Helicopter trauma transport: an overview of recent outcomes and triage literature

PURPOSE OF REVIEW

The purpose of this review is to assess literature pertinent to outcomes benefits accrued by the use of helicopter emergency medical services for trauma transport. A previous annotated bibliography assessed literature published between 1980 and 2000. The goal of this paper is to address developments since fall 2001, and to cast recent studies in the light of earlier work in an attempt to provide a long-range overview of the relevant literature.

RECENT FINDINGS

In the year covered by this review, we identified four papers that directly assessed the association between the helicopter emergency medical services utilization and trauma outcome, and three that addressed the closely related issue of the helicopter emergency medical services triage appropriateness. An Italian study found no benefit associated with advanced prehospital care for patients with severe head injury. A US multicenter trial assessing blunt trauma transports found a substantial mortality reduction associated with helicopter use. Two other US studies, characterized by a similar 'natural experiment' design of assessing mortality changes on either side of a timepoint at which the helicopter emergency medical services availability ceased, reached opposite conclusions about the benefits of the service. Recent studies addressing the helicopter emergency medical services utilization in terms of triage were characterized by varying levels of agreement with the widely held belief that this service is characterized by overtriage.

SUMMARY

The preponderance of recent and previously extant evidence supports an argument that the helicopter emergency medical services transport is associated with significant benefit for some injured patients. The primary challenges at this time include the determination of which patients benefit and the elucidation of which aspects of the helicopter emergency medical services are responsible for any salutary effects of its utilization.

Multimodality monitoring in severe head injury

PURPOSE OF REVIEW

This review describes recent advances in multimodal neuromonitoring of patients following severe head injury during the period from 2001 to 2002.

RECENT FINDINGS

Monitoring intracranial pressure is considered a standard part of therapy despite a lack of randomized studies comparing patients with and without intracranial pressure monitoring. Jugular oximetry and brain tissue oxygen pressure monitoring are being used more frequently as part of a treatment protocol. Intracerebral microdialysis, despite the widespread use as a research tool, still cannot be considered a standard in clinical monitoring. These new monitoring devices may provide useful insight into the evolution of brain injury.

SUMMARY

Technology is rapidly changing the nature of neuromonitoring. New devices are becoming available which make the monitoring truly multimodal. Studies are needed to determine how to best incorporate these new parameters into effective management protocols.

Hyperventilation following aero-medical rapid sequence intubation may be a deliberate response to hypoxemia

BACKGROUND

Recent studies document a high incidence of hyperventilation by prehospital providers, with a potentially detrimental effect on outcome in traumatic brain injury (TBI).

PURPOSE

To document the incidence of hyperventilation by aero-medical providers and explore a possible relationship between hyperventilation episodes and desaturations or impending hypoxemia.

METHODS

This was a prospective, descriptive study using TBI patients undergoing prehospital RSI by aero-medical crews. Continuous data regarding end-tidal CO2 (EtCO2), ventilatory rate, and oxygen saturation (SpO2) were downloaded from hand-held oximeter-capnometer devices. Two investigators independently assessed oximetry/capnometry data to identify the following occurrences: desaturation during RSI (SpO2 < 90%), impending hypoxemia (SpO2 decrease by >or=3% to a value <95%) following intubation, loss of SpO2 signal, hyperventilation (EtCO2<30 mm Hg), and severe hyperventilation (EtCO2 < 25 mm Hg). Covariate analysis was used to explore the possible association between hyperventilation episodes and either desaturation, impending hypoxemia, or loss of SpO2 signal.

RESULTS

A total of 32 aero-medical patients were enrolled with a mean duration of ventilation monitoring of 14.8 min. The incidence of hyperventilation or severe hyperventilation was substantially lower than previously documented with ground paramedics. A total of 28 hyperventilation episodes were identified in 16 patients; 13 of these were associated with impending hypoxemia following intubation, five were associated with desaturation during RSI, and seven were associated with loss of SpO2 signal. The remaining three occurred immediately following intubation without desaturation during RSI. Desaturation was observed in 62% of patients; of note, desaturation was recorded on the quality improvement document in only 23% of these. Covariate analysis revealed an association between hyperventilation episodes and either desaturatios during RSI, impending hypoxemia following intubation, or loss of SpO2 signal.

CONCLUSIONS

The incidence of hyperventilation by aeromedical crews was lower than reported for ground paramedics and appears to occur in response to desaturation, impending hypoxemia, or loss of SpO2 signal.

Special Cases: Mechanical Ventilation of Neurosurgical Patients

Mechanical ventilation has evolved greatly over the last half century, guided primarily by improved comprehension of the relevant pathology/physiology. Neurosurgical patients are a unique subgroup of patients who heavily use this technology for both support, and less commonly, as a therapy. Such patients demand special consideration with regard to mode of ventilation, use of positive end-expiratory pressure, and monitoring. In addition, meeting the ventilatory needs of neurosurgical patients while minimizing ventilatory-induced lung damage can be a challenging aspect of care.

Sidestream end-tidal carbon dioxide monitoring during helicopter transport

INTRODUCTION

End-tidal carbon dioxide (EtCO(2)) monitoring is standard of care for intubated patients. Sidestream technology also allows EtCO(2) monitoring in non-intubated patients. This is the first study to evaluate the feasibility of monitoring sidestream EtCO(2) on intubated and non-intubated patients during helicopter transport.

SETTING

An air medical transport program serving two level 1 trauma centers.

METHODS

In this prospective observational study, sidestream EtCO2 was monitored in 100 consecutive patients transported by helicopter. Flight nurses rated the difficulty posed by various factors of sidestream monitoring. An experienced flight nurse and a clinical engineer evaluated waveforms and EtCO(2) values.

RESULTS

Only 1 of the 100 transported patients required a change from sidestream to mainstream EtCO(2) monitoring. Moisture was noted in the tubing of two patients, and one was changed to mainstream. Eleven patients had occluded nares but were not changed to mainstream monitoring. On a 5-point Likert scale, responses to statements regarding difficulty with length of tubing, patient tolerance, and interference with patient care produced mean scores of 0.5 (range, 0-3). Responses regarding difficulty securing the cannula yielded a mean score of 0.7 (range, 0-3). Of 1,685 (99%) recorded EtCO(2) values, 1,668 met pre-established criteria for "consistent." Alveolar plateaus were identified in 81 of 94 (86%) patient waveforms by the flight nurse and 73 of 94 (78%) patient waveforms by the clinical engineer.

CONCLUSION

Sidestream EtCO(2) monitoring is feasible during air medical transport of both intubated and non-intubated patients. The mechanism was easy to use, and consistent numeric values and waveforms with alveolar plateaus were obtained in a large majority of readings.

The Use of Quantitative End-Tidal Capnometry to Avoid Inadvertent Severe Hyperventilation in Patients With Head Injury After Paramedic Rapid Sequence Intubation

BACKGROUND

This study aimed to determine whether field end-tidal carbon dioxide CO2 (ETCO2) monitoring decreases inadvertent severe hyperventilation after paramedic rapid sequence intubation.

METHODS

Data were collected prospectively as part of the San Diego Paramedic Rapid Sequence Intubation Trial, which enrolled adults with severe head injuries (Glasgow Coma Score, 3-8) that could not be intubated without neuromuscular blockade. After preoxygenation, the patients underwent rapid sequence intubation using midazolam and succinylcholine. A maximum of three intubation attempts were allowed before Combitube insertion was mandated. Tube confirmation was accomplished by physical examination, qualitative capnometry, pulse oximetry, and syringe aspiration. Standard ventilation parameters (tidal volume, 800 mL; 12 breaths/minute) were taught. One agency used portable ETCO2 monitors, with ventilation modified to target ETCO2 values of 30 to 35 mm Hg. Trial patients transported by aeromedical crews also underwent ETCO2 monitoring. The primary outcome measure was the incidence of inadvertent severe hyperventilation, defined as arterial blood gas partial pressure of CO2 (pCO2) of less than 25 mm Hg at arrival, for patients with and those without ETCO2 monitoring. These groups also were compared in terms of age, gender, clinical presentation, Abbreviated Injury Score, Injury Severity Score, arrival arterial blood gas data, and survival.

RESULTS

The study enrolled 426 patients and administered neuromuscular blocking agents to 418 patients. Endotracheal intubation was successful for 355 of these patients (85.2%). Another 58 patients (13.6%) underwent Combitube insertion. For 291 successfully intubated patients, arrival pCO2 values were documented, with continuous ETCO2 monitoring performed for 144 of these patients (49.4%). Patients with ETCO2 monitoring had a lower incidence of inadvertent severe hyperventilation than those without ETCO2 monitoring (5.6% vs. 13.4%; odds ratio, 2.64; 95% confidence interval, 1.12-6.20; p = 0.035). There were no significant differences in terms of age, gender, clinical presentation, Abbreviated Injury Score, Injury Severity Score, arrival partial pressure of oxygen (PO2) and pH, or survival. The patients in both groups with severe hyperventilation had a significantly higher mortality rate than the patients without hyperventilation (56 vs. 30%; odds ratio, 2.9; 95% confidence interval, 1.3-6.6; p = 0.016), which could not be explained solely on the basis of their injuries.

CONCLUSIONS

The use of ETCO2 monitoring is associated with a decrease in inadvertent severe hyperventilation.