Abbreviated Injury Scale: not a reliable basis for summation of injury severity in trauma facilities?

BACKGROUND: Injury severity is most frequently classified using the Abbreviated Injury Scale (AIS) as a basis for the Injury Severity Score (ISS) and the New Injury Severity Score (NISS), which are used for assessment of overall injury severity in the multiply injured patient and in outcome prediction. European trauma registries recommended the AIS 2008 edition, but the levels of inter-rater agreement and reliability of ISS and NISS, associated with its use, have not been reported. METHODS: Nineteen Norwegian AIS-certified trauma registry coders were invited to score 50 real, anonymised patient medical records using AIS 2008. Rater agreements for ISS and NISS were analysed using Bland-Altman plots with 95% limits of agreement (LoA). A clinically acceptable LoA range was set at ± 9 units. Reliability was analysed using a two-way mixed model intraclass correlation coefficient (ICC) statistics with corresponding 95% confidence intervals (CI) and hierarchical agglomerative clustering. RESULTS: Ten coders submitted their coding results. Of their AIS codes, 2189 (61.5%) agreed with a reference standard, 1187 (31.1%) real injuries were missed, and 392 non-existing injuries were recorded. All LoAs were wider than the predefined, clinically acceptable limit of ± 9, for both ISS and NISS. The joint ICC (range) between each rater and the reference standard was 0.51 (0.29,0.86) for ISS and 0.51 (0.27,0.78) for NISS. The joint ICC (range) for inter-rater reliability was 0.49 (0.19,0.85) for ISS and 0.49 (0.16,0.82) for NISS. Univariate linear regression analyses indicated a significant relationship between the number of correctly AIS-coded injuries and total number of cases coded during the rater's career, but no significant relationship between the rater-against-reference ISS and NISS ICC values and total number of cases coded during the rater's career. CONCLUSIONS: Based on AIS 2008, ISS and NISS were not reliable for summarising anatomic injury severity in this study. This result indicates a limitation in their use as benchmarking tools for trauma system performance.

Classification of comorbidity in trauma: the reliability of pre-injury ASA physical status classification.

BACKGROUND: Pre-injury comorbidities can influence the outcomes of severely injured patients. Pre-injury comorbidity status, graded according to the American Society of Anesthesiologists Physical Status (ASA-PS) classification system, is an independent predictor of survival in trauma patients and is recommended as a comorbidity score in the Utstein Trauma Template for Uniform Reporting of Data. Little is known about the reliability of pre-injury ASA-PS scores. The objective of this study was to examine whether the pre-injury ASA-PS system was a reliable scale for grading comorbidity in trauma patients. METHODS: Nineteen Norwegian trauma registry coders were invited to participate in a reliability study in which 50 real but anonymised patient medical records were distributed. Reliability was analysed using quadratic weighted kappa (κ(w)) analysis with 95% CI as the primary outcome measure and unweighted kappa (κ) analysis, which included unknown values, as a secondary outcome measure. RESULTS: Fifteen of the invitees responded to the invitation, and ten participated. We found moderate (κ(w)=0.77 [95% CI: 0.64-0.87]) to substantial (κ(w)=0.95 [95% CI: 0.89-0.99]) rater-against-reference standard reliability using κ(w) and fair (κ=0.46 [95% CI: 0.29-0.64]) to substantial (κ=0.83 [95% CI: 0.68-0.94]) reliability using κ. The inter-rater reliability ranged from moderate (κ(w)=0.66 [95% CI: 0.45-0.81]) to substantial (κ(w)=0.96 [95% CI: 0.88-1.00]) for κ(w) and from slight (κ=0.36 [95% CI: 0.21-0.54]) to moderate (κ=0.75 [95% CI: 0.62-0.89]) for κ. CONCLUSIONS: The rater-against-reference standard reliability varied from moderate to substantial for the primary outcome measure and from fair to substantial for the secondary outcome measure. The study findings indicate that the pre-injury ASA-PS scale is a reliable score for classifying comorbidity in trauma patients.

Law, ethics and clinical judgment in end-of-life decisions--how do Norwegian doctors think?

AIM: According to Norwegian law, an autonomous patient has the right to refuse life-prolonging treatment. If the patient is not defined as dying, however, health personnel are obliged to instigate life-saving treatment in an emergency situation even against the patient's wishes. The purpose of this study was to investigate how doctors' attitudes and knowledge agree with these legal provisions, and how the statutory provision on emergency situations influences the principle of patient autonomy for severely ill, but not dying, patients. METHOD: A strategic sample of 1175 Norwegian doctors who are specialists in internal medicine, paediatrics, surgery, neurology and neurosurgery received a mail questionnaire about decisions on end-of-life care in hypothetical scenarios. The case presented concerns a 45-year-old autonomous patient diagnosed with end-stage ALS who declines ventilatory treatment. Recipients were randomly selected from the membership roster of the Norwegian Medical Association. 640 (54.5%) responded; of these, 406 had experience with end-of-life decisions. RESULTS: 56.1% (221/394) stated that ALS patients in such situations can always refuse life-prolonging treatment, and 42.4% (167/394) were of the opinion that the patient can normally refuse life-prolonging treatment. 1.5% (6/394) stated that the patient cannot refuse life-prolonging treatment. CONCLUSIONS: The answers indicate that the respondents include patients' refusal in an overall clinical judgement, and interpret patients' right to decline life-saving treatment in different ways. This may reflect the complex legal situation in Norway regarding patient autonomy with respect to the right of severely ill, but not dying, patients' right to decline acute life-saving treatment.

Dynamic effects of adrenaline (epinephrine) in out-of-hospital cardiac arrest with initial pulseless electrical activity (PEA).

BACKGROUND: In cardiac arrest, pulseless electrical activity (PEA) is a challenging clinical syndrome. In a randomized study comparing intravenous (i.v.) access and drugs versus no i.v. access or drugs during advanced life support (ALS), adrenaline (epinephrine) improved return of spontaneous circulation (ROSC) in patients with PEA. Originating from this study, we investigated the time-dependent effects of adrenaline on clinical state transitions in patients with initial PEA, using a non-parametric multi-state statistical model. METHODS AND RESULTS: Patients with available defibrillator recordings were included, of whom 101 received adrenaline and 73 did not. There were significantly more state transitions in the adrenaline group than in the no-adrenaline group (rate ratio = 1.6, p<0.001). Adrenaline markedly increased the rate of transition from PEA to ROSC during ALS and slowed the rate of being declared dead; e.g. by 20 min 20% of patients in the adrenaline group had been declared dead and 25% had obtained ROSC, whereas 50% in the no-adrenaline group have been declared dead and 15% had obtained ROSC. The differential effect of adrenaline could be seen after approx. 10 min of ALS for most transitions. For both groups the probability of deteriorating from PEA to asystole was highest during the first 15 min. Adrenaline increased the rate of transition from PEA to ventricular fibrillation or -tachycardia (VF/VT), and from ROSC to VF/VT. CONCLUSIONS: Adrenaline has notable clinical effects during ALS in patients with initial PEA. The drug extends the time window for ROSC to develop, but also renders the patient more unstable. Further research should investigate the optimal dose, timing and mode of adrenaline administration during ALS.

A field evaluation of real-life motor vehicle accidents: presence of unrestrained objects and their association with distribution and severity of patient injuries.

Moving objects may pose an added threat to car occupants in motor vehicle accidents (MVAs). However, to our knowledge, there have only been two case studies published on the subject. For the present study, accident reports and photo documentation from MVAs were collected on-scene by dedicated paramedics. Emergency medical service personnel on-scene were interviewed as necessary. Potentially harmful unrestrained objects in the involved motor vehicles (MVs) were identified and categorised by type, weight and hardness. Seatback offset by unrestrained objects was noted. The patient injury distribution (Abbreviated Injury Scale (AIS) body regions) and severity (AIS severity scores and New Injury Severity Score (NISS) scores) were retrospectively determined from hospital and autopsy records, and their potential relationship to unrestrained objects was explored. A total of 190 accidents involving 338 MVs and 618 individuals were included. In total, 327 individuals (53%) were injured, and 61 (10%) died. 37 of 61 were not autopsied. The mean NISS was 17 (median 8, interquartile range (IQR) 1-27). Unrestrained objects were reported for 133 motor vehicles (39%) involving 293 individuals. 35% of the unrestrained objects found in the passenger compartment weighed >2 kg. In the boot, 32% of objects weighed >20 kg. Seatback offset associated with unrestrained objects was found for 45 individuals (15%). Unrestrained objects originally located in the boot (heavy luggage, groceries and tyres were the most frequently reported) had moved into the passenger compartment on impact in 27 cases, 24 of which were associated with seatback offset. An in-depth analysis was performed on 24 patients whose injuries were highly likely to be associated with unrestrained objects, as indicated by accident reports and medical documentation. Nineteen (79%) were involved in frontal collisions, and 12 (50%) died on-scene. The mean NISS was 51.7 (median 51, IQR 27-75) in the 17 (71%) patients with seatback offset and 37.2 (median 41, IQR 22.5-50) in the 7 (29%) without seatback offset. Seatback offset was associated with more severe head and thoracic injuries and an increased incidence of abdominal and pelvic injuries. Patients injured by unrestrained objects while sitting in unharmed car seats predominantly suffered head, cervical spine and thoracic injuries. Our results indicate a need for public information campaigns. The development of car backseats that can better sustain hits from heavy objects in the cargo boot is an important area for the motor vehicle production industry to explore.

High school students as ambassadors of CPR--a model for reaching the most appropriate target population?

BACKGROUND: There is mismatch in age between those usually trained in CPR and those witnessing out-of-hospital cardiac arrest with mean age reported at 30 and 65 years old, respectively. Two tier mass CPR self-training with manikin-DVD sets using school children has been reported. We have studied high school students as first tier and encouraged them to train older people. METHODS: Four separate groups were tested: students before or after training and second tier adults before or after training with first tier students as facilitators. CPR performance was videotaped and electronically documented on a Skillmeter Anne manikin. RESULTS: Each student reported to train mean 2.8 extra persons, and 43% were aged 50 or older. Pre-training results were poor, while first and second tier persons performed equally well after training, and within ERC guideline recommendations. CONCLUSIONS: People trained at home with a manikin-DVD set and high school students as facilitators were able to perform CPR as recommended by ERC guidelines with a reasonable percentage aged 50 or older.

Which factors influence spontaneous state transitions during resuscitation?

BACKGROUND: The clinical state (i.e. ventricular fibrillation/tachycardia: VF/VT, asystole: ASY, pulseless electrical activity: PEA, or return of spontaneous circulation, ROSC) during cardiopulmonary resuscitation determines patient management. We investigate how spontaneous transitions (i.e. not forced by DC shock) between these states are influenced by factors like age, gender, bystander CPR, CPR quality, proportion of time spent in a state, or the number of state transitions. METHODS: Detailed recordings from CPR attempts in 304 out-of-hospital cardiac arrests in Akershus (Norway), Stockholm (Sweden), and London (UK) were obtained from modified Heartstart 4000 defibrillators. Spontaneous state transitions were studied using a non-parametric intensity regression method that can handle dynamic factors like the state history properly. RESULTS: The initial state tended to preserve itself, as did cumulative time in any state. Recent DC shock, bystander CPR, location, response time, gender, compression depth, and ventilation rate were important for some transitions. More ventilation during PEA might possibly avert development to ASY and favour ROSC; otherwise observed variations in CPR quality had little impact. CONCLUSION: Using a novel intensity regression approach we studied the influence of various factors on spontaneous (i.e. non-shock) state transitions during CPR. State development was largely determined by the initial state, the proportion of time spent in a state, and the transition frequency; all probably reflecting the underlying aetiology.

The effect of transport on quality of cardiopulmonary resuscitation in out-of-hospital cardiac arrest.

INTRODUCTION: Most manikin and clinical studies have found decreased quality of CPR during transport to hospital. We wanted to study quality of CPR before and during transport for out-of-hospital cardiac arrest patients and also whether quality of CPR before initiation of transport was different from the quality in patients only receiving CPR on scene. MATERIALS AND METHODS: Quality of CPR was prospectively registered with a modified defibrillator for consecutive cases of out-of-hospital cardiac arrest in three ambulance services during 2002-2005. Ventilations were registered via changes in transthoracic impedance and chest compressions were measured with an extra chest compression pad placed on the patients' sternum. Paired t-tests were used to analyse quality of CPR before vs. during transport with ongoing CPR. Unpaired t-tests were used to compare CPR quality prior to transport to CPR quality in patients with CPR terminated on site. RESULTS: Quality of CPR did not deteriorate during transport, but as previously reported overall quality of CPR was substandard. Quality of CPR performed on site was significantly better when transport was not initiated with ongoing CPR compared to episodes with initiation of transport during CPR: fraction of time without chest compressions was 0.45 and 0.53 (p<0.001), compression depth 37 mm and 34 mm (p=0.04), and number of chest compressions per minute 61 and 56 (p=0.01), respectively. CONCLUSION: CPR quality was sub-standard both before and during transport. Early decision to transport might have negatively affected CPR quality from the early stages of resuscitation.

Using ontologies to integrate and share resuscitation data from diverse medical devices.

OBJECTIVE: To propose a method for standardised data representation and demonstrate a technology that makes it possible to translate data from device dependent formats to this standard representation format. METHODS AND RESULTS: Outcome statistics vary between emergency medical systems organising resuscitation services. Such differences indicate a potential for improvement by identifying factors affecting outcome, but data subject to analysis have to be comparable. Modern technology for communicating information makes it possible to structure, store and transfer data flexibly. Ontologies describe entities in the world and how they relate. Letting different computer systems refer to the same ontology results in a common understanding on data content. Information on therapy such as shock delivery, chest compressions and ventilation should be defined and described in a standardised ontology to enable comparison and combining data from diverse sources. By adding rules and logic data can be merged and combined in new ways to produce new information. An example ontology is designed to demonstrate the feasibility and value of such a standardised structure. CONCLUSIONS: The proposed technology makes possible capturing and storing of data from different devices in a structured and standardised format. Data can easily be transformed to this standardised format, compared and combined independent of the original structure.

Development of the probability of return of spontaneous circulation in intervals without chest compressions during out-of-hospital cardiac arrest: an observational study.

BACKGROUND: One of the factors that limits survival from out-of-hospital cardiac arrest is the interruption of chest compressions. During ventricular fibrillation and tachycardia the electrocardiogram reflects the probability of return of spontaneous circulation associated with defibrillation. We have used this in the current study to quantify in detail the effects of interrupting chest compressions. METHODS: From an electrocardiogram database we identified all intervals without chest compressions that followed an interval with compressions, and where the patients had ventricular fibrillation or tachycardia. By calculating the mean-slope (a predictor of the return of spontaneous circulation) of the electrocardiogram for each 2-second window, and using a linear mixed-effects statistical model, we quantified the decline of mean-slope with time. Further, a mapping from mean-slope to probability of return of spontaneous circulation was obtained from a second dataset and using this we were able to estimate the expected development of the probability of return of spontaneous circulation for cases at different levels. RESULTS: From 911 intervals without chest compressions, 5138 analysis windows were identified. The results show that cases with the probability of return of spontaneous circulation values 0.35, 0.1 and 0.05, 3 seconds into an interval in the mean will have probability of return of spontaneous circulation values 0.26 (0.24-0.29), 0.077 (0.070-0.085) and 0.040(0.036-0.045), respectively, 27 seconds into the interval (95% confidence intervals in parenthesis). CONCLUSION: During pre-shock pauses in chest compressions mean probability of return of spontaneous circulation decreases in a steady manner for cases at all initial levels. Regardless of initial level there is a relative decrease in the probability of return of spontaneous circulation of about 23% from 3 to 27 seconds into such a pause.

Precision of field triage in patients brought to a trauma centre after introducing trauma team activation guidelines.

BACKGROUND: Field triage is important for regional trauma systems providing high sensitivity to avoid that severely injured are deprived access to trauma team resuscitation (undertriage), yet high specificity to avoid resource over-utilization (overtriage). Previous informal trauma team activation (TTA) at Ulleval University Hospital (UUH) caused imprecise triage. We have analyzed triage precision after introduction of TTA guidelines. METHODS: Retrospective analysis of 7 years (2001-07) of prospectively collected trauma registry data for all patients with TTA or severe injury, defined as at least one of the following: Injury Severity Score (ISS) > 15, proximal penetrating injury, admitted ICU > 2 days, transferred intubated to another hospital within 2 days, dead from trauma within 30 days. Interhospital transfers to UUH and patients admitted by non-healthcare personnel were excluded. Overtriage is the fraction of TTA where patients are not severely injured (1-positive predictive value); undertriage is the fraction of severely injured admitted without TTA (1-sensitivity). RESULTS: Of the 4,659 patients included in the study, 2,221 (48%) were severely injured. TTA occurred 4,440 times, only 2,002 of which for severely injured (overtriage 55%). Overall undertriage was 10%. Mechanism of injury was TTA criterion in 1,508 cases (34%), of which only 392 were severely injured (overtriage 74%). Paramedic-manned prehospital services provided 66% overtriage and 17% undertriage, anaesthetist-manned services 35% overtriage and 2% undertriage. Falls, high age and admittance by paramedics were significantly associated with undertriage. A Triage-Revised Trauma Score (RTS) < 12 in the emergency department reduced the risk for undertriage compared to RTS = 12 (normal value). Field RTS was documented by anaesthetists in 64% of the patients compared to 33% among paramedics.Patients subject to undertriage had an ISS-adjusted Odds Ratio for 30-day mortality of 2.34 (95% CI 1.6-3.4, p < 0.001) compared to those correctly triaged to TTA. CONCLUSION: Triage precision had not improved after TTA guideline introduction. Anaesthetists perform precise trauma triage, whereas paramedics have potential for improvement. Skewed mission profiles makes comparison of differences in triage precision difficult, but criteria or the use of them may contribute. Massive undertriage among paramedics is of grave concern as patients exposed to undertriage had increased risk of dying.

Representing resuscitation data-Considerations on efficient analysis of quality of cardiopulmonary resuscitation.

OBJECTIVE: To discuss challenges in representing resuscitation data from Utstein style reports and devices like defibrillators with focus on unified and efficient handling of variety of resuscitation research objectives. METHODS AND RESULTS: Information on therapy such as shock delivery, chest compressions and ventilation can be extracted from defibrillators. A method for merging this information with cardiac rhythm annotated from ECGs, yields a representation of the resuscitation episode with cardiac rhythm also giving information on response to therapy. These data should be synchronised to an electronic Utstein report. With modern technology for communicating information it is possible to structure, store and transport data flexibly so that data captured with devices from different manufacturers can be combined. CONCLUSIONS: A scheme for representing resuscitation data should combine essential information stored in different locations after a resuscitation attempt. The resulting representation should enable data analysis to enable studies of the relationship between therapy and patient response. As the complexity and amount of data generated during resuscitation efforts are ever increasing, the time is mature for using modern information technology tools to provide infrastructure for efficient data management and analysis to identify and meet future challenges in resuscitation data analysis.

Progressing from initial non-shockable rhythms to a shockable rhythm is associated with improved outcome after out-of-hospital cardiac arrest.

BACKGROUND: Cardiac arrest patients with initial non-shockable rhythm progressing to shockable rhythm have been reported to have inferior outcome to those remaining non-shockable. We wanted to confirm this observation in our prospectively collected database, and assess whether differences in cardiopulmonary resuscitation (CPR) quality could help to explain any such difference in outcome. MATERIALS AND METHODS: All out-of-hospital cardiac arrest (OHCA) cases in the Oslo EMS between May 2003 and April 2008 were retrospectively studied, and cases with initial asystole or pulseless electrical activity (PEA) were selected. Pre-hospital and hospital records, Utstein forms, and continuous ECGs were reviewed. Quality of CPR and outcome were compared for patients who progressed to a shockable rhythm and patients who remained in non-shockable rhythms. RESULTS: Of 753 cases with initial non-shockable rhythms 517 (69%) had asystole and 236 (31%) PEA. Ninety-eight (13%) patients progressed to a shockable rhythm, while 653 (87%) remained non-shockable during the entire resuscitation effort (two unknown). Hands-off ratio was higher in the shockable than the non-shockable group, 0.21+/-0.12 vs. 0.16+/-0.10 (p=0.000) with no significant difference in compression and ventilation rates. Overall survival to hospital discharge was 3%; 7% in the shockable and 2% in the non-shockable group (p=0.014). Based on a multivariate logistic analysis young age, initial PEA, and progressing to a shockable rhythm were associated with better outcome. CONCLUSION: Progressing from initial non-shockable rhythms to a shockable rhythm was associated with improved outcome after OHCA. This occurred despite more pauses in chest compressions in the shockable group, probably related to defibrillation attempts.

The Utstein template for uniform reporting of data following major trauma: a joint revision by SCANTEM, TARN, DGU-TR and RITG.

BACKGROUND: In 1999, an Utstein Template for Uniform Reporting of Data following Major Trauma was published. Few papers have since been published based on that template, reflecting a lack of international consensus on its feasibility and use. The aim of the present revision was to further develop the Utstein Template, particularly with a major reduction in the number of core data variables and the addition of more precise definitions of data variables. In addition, we wanted to define a set of inclusion and exclusion criteria that will facilitate uniform comparison of trauma cases. METHODS: Over a ten-month period, selected experts from major European trauma registries and organisations carried out an Utstein consensus process based on a modified nominal group technique. RESULTS: The expert panel concluded that a New Injury Severity Score > 15 should be used as a single inclusion criterion, and five exclusion criteria were also selected. Thirty-five precisely defined core data variables were agreed upon, with further division into core data for Predictive models, System Characteristic Descriptors and for Process Mapping. CONCLUSION: Through a structured consensus process, the Utstein Template for Uniform Reporting of Data following Major Trauma has been revised. This revision will enhance national and international comparisons of trauma systems, and will form the basis for improved prediction models in trauma care.

Improving cardiopulmonary resuscitation quality to ensure survival.

PURPOSE OF REVIEW: There is correlation between quality of bystander cardiopulmonary resuscitation and patient survival. Recent developments in defibrillator technology enable recording of cardiopulmonary resuscitation quality, and have shown quality of professional cardiopulmonary resuscitation far from guidelines' levels for factors such as chest compression depth and rate, ventilation rate, and pauses in chest compressions. The effects of cardiopulmonary resuscitation quality factors on patient survival are presently under scrutiny. RECENT FINDINGS: Factors such as depth of and pauses in chest compressions immediately before defibrillation attempts affect outcome. Both immediate automated feedback on cardiopulmonary resuscitation quality and use of the same quality data during postevent debriefing improve cardiopulmonary resuscitation quality, and the combination appears to improve outcome. The increased awareness of quality problems, particularly unwanted pauses in chest compressions, has caused more emphasis on chest compressions in cardiopulmonary resuscitation protocols including the 2005 Guidelines. There is a growing number of reports of increased survival with these new protocols. SUMMARY: Cardiopulmonary resuscitation quality affects survival after cardiac arrest. Reporting cardiopulmonary resuscitation quality data should be standard in all studies of cardiac arrest as effects of studied interventions can depend on or influence cardiopulmonary resuscitation quality. These data are also valuable in quality improvement processes both in-hospital and out-of-hospital.

Dynamics and state transitions during resuscitation in out-of-hospital cardiac arrest.

BACKGROUND: The state or rhythm during resuscitation, i.e. ventricular fibrillation/tachycardia (VF/VT), asystole (ASY), pulseless electrical activity (PEA), or return of spontaneous circulation (ROSC) determines management. The state is unstable and will change either spontaneously (e.g. PEA-->ASY) or by intervention (e.g. VF-->ASY after DC shock); temporary ROSC may also occur. To gain insight into the dynamics of this process, we analyzed the state transitions over time using real-life data. METHODS: Detailed recordings from 304 episodes of attempted resuscitation from out-of-hospital cardiac arrests of presumed cardiac etiology were obtained from modified Heartstart 4000 defibrillators. State transitions were visualized and described, and analyzed in terms of a Markov probability model. RESULTS: The median number of state transitions was 5 (range 1-39), and more transitions were observed with VF than PEA or asystole as the initial rhythm. Of 105 patients (35%) who regained ROSC at some point during CPR, only 65 (21%) achieved sustained ROSC; suggesting an unrealized survival potential. A 3-min transition probability matrix was estimated: for example, a patient early in VF has a probability of 31% to be in ASY, 32% of still being in VF, 5% to have temporary ROSC, and 2% to have sustained ROSC after 3 min. CONCLUSION: The dynamics of resuscitation can be described in terms of state transitions and a Markov probability model. This framework enables prediction of short-term clinical development, supports informed decisions during CPR, and suggests a novel area for research.

Transthoracic impedance changes as a tool to detect malpositioned tracheal tubes.

BACKGROUND: Undetected malpositioned or dislodged ventilation tubes during cardiac arrest have fatal consequences, and no single method can detect the tube position reliably during such low-flow states. We wanted to test the ability of impedance changes as measured across the chest via the standard defibrillation pads to distinguish between oesophageal and tracheal ventilations in non-circulated patients. MATERIALS AND METHODS: After the end of futile resuscitation transthoracic impedance was measured with a prototype defibrillator, and ventilation variables were collected with a spirometer-capnography unit during tracheal ventilations and after repositioning of the tube; during oesophageal ventilations for paired comparisons. RESULTS: We registered 123 oesophageal and 178 tracheal ventilations in nine patients. Transthoracic impedance changes associated with ventilations were always larger during tracheal than oesophageal ventilations (mean difference 1.3 ohms (95% CI 1.0, 1.5), P<0.001), and all such changes above 1.2 ohms were associated with tracheal ventilations, while changes below 0.4 ohms always were associated with oesophageal ventilations. By subtracting 0.5 ohms from the individual mean transthoracic change associated with tracheal ventilations, tube position was predicted with sensitivity 0.99 and specificity 0.97. CONCLUSION: Transthoracic impedance changes may be used to detect malpositioned and dislodged tubes also during situations without spontaneous circulation. Our predictive values must be retested in another population.