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Biomedical subjects

Petter Andreas Steen

Publications and source records attributed to Petter Andreas Steen.

At least 19 recordsLinked to original sources
PubMed2006

Quality of out-of-hospital cardiopulmonary resuscitation with real time automated feedback: a prospective interventional study.

AIMS: To compare quality of CPR during out-of-hospital cardiac arrest with and without automated feedback. MATERIALS AND METHODS: Consecutive adult, out-of-hospital cardiac arrests of all causes were studied. One hundred and seventy-six episodes (March 2002-October 2003) without feedback were compared to 108 episodes (October 2003-September 2004) where automatic feedback on CPR was given. Automated verbal and visual feedback was based on measured quality with a prototype defibrillator. Quality of CPR was the main outcome measure and survival was reported as specified in the protocol. RESULTS: Average compression depth increased from (mean +/- S.D.) 34 +/- 9 to 38 +/- 6 mm (mean difference (95% CI) 4 (2, 6), P < 0.001), and median percentage of compressions with adequate depth (38-51 mm) increased from 24% to 53% (P < 0.001, Mann-Whitney U-test) with feedback. Mean compression rate decreased from 121 +/- 18 to 109 +/- 12 min(-1) (difference -12 (-16, -9), P = 0.001). There were no changes in the mean number of ventilations per minute; 11 +/- 5 min(-1) versus 11 +/- 4 min(-1) (difference 0 (-1, 1), P = 0.8) or the fraction of time without chest compressions; 0.48 +/- 0.18 versus 0.45 +/- 0.17 (difference -0.03 (-0.08, 0.01), P = 0.08). With intention to treat analysis 7/241 control patients were discharged alive (2.9%) versus 5/117 with feedback (4.3%) (OR 1.5 (95% CI; 0.8, 3), P = 0.2). In a logistic regression analysis of all cases, witnessed arrest (OR 4.2 (95% CI; 1.6, 11), P = 0.004) and average compression depth (per mm increase) (OR 1.05 (95% CI; 1.01, 1.09), P = 0.02) were associated with rate of hospital admission. CONCLUSIONS: Automatic feedback improved CPR quality in this prospective non-randomised study of out-of-hospital cardiac arrest. Increased compression depth was associated with increased short-term survival. TRIAL REGISTRATION: ClinicalTrials.gov (NCT00138996), http://www.clinicaltrials.gov/.

Aged↗
PubMed2006

Quality of lay person CPR performance with compression: ventilation ratios 15:2, 30:2 or continuous chest compressions without ventilations on manikins.

The new CPR guidelines emphasise chest compression depth and have increased the compression:ventilation ratio to cause less time intervals without chest compressions. How this change may influence the quality of chest compressions is not documented. Sixty-eight volunteers among travellers at Oslo international airport and a senior citizen centre performed 5 min of CPR on a manikin with compression:ventilation ratios 15:2, 30:2 or continuous chest compressions. Median age was 37.5 years (range 15-87), 59% were men, and 71% reported CPR training median 8 years (3-15) previously. Three of 22, 4 of 23 and 3 of 23 subjects in the 15:2, 30:2 and continuous compressions groups respectively stopped before 5 min had passed. Mean compression depth was 41 +/- 11, 45 +/- 8 and 30 +/- 8 mm, respectively. Depth was reduced as a function of time in the continuous compression group. Number of compressions per minute was 40 +/- 9, 43 +/- 14 and 73 +/- 24 and percent no flow time 49 +/- 13%, 38 +/- 20% and 1 +/- 2%, respectively. In conclusion, continuous chest compressions without ventilations gave significantly more chest compressions per minute, but with decreased compression quality. No flow time for 30:2 was significantly less than for 15:2.

Adolescent↗
PubMed2006

Haemodynamic effects of adrenaline (epinephrine) depend on chest compression quality during cardiopulmonary resuscitation in pigs.

BACKGROUND: Adrenaline (epinephrine) is used during cardiopulmonary resuscitation (CPR) based on animal experiments without supportive clinical data. Clinically CPR was reported recently to have much poorer quality than expected from international guidelines and what is generally done in laboratory experiments. We have studied the haemodynamic effects of adrenaline during CPR with good laboratory quality and with quality simulating clinical findings and the feasibility of monitoring these effects through VF waveform analysis. METHODS AND RESULTS: After 4 min of cardiac arrest, followed by 4 min of basic life support, 14 pigs were randomised to ClinicalCPR (intermittent manual chest compressions, compression-to-ventilation ratio 15:2, compression depth 30-38 mm) or LabCPR (continuous mechanical chest compressions, 12 ventilations/min, compression depth 45 mm). Adrenaline 0.02 mg/kg was administered 30 s thereafter. Plasma adrenaline concentration peaked earlier with LabCPR than with ClinicalCPR, median (range), 90 (30, 150) versus 150 (90, 270) s (p = 0.007), respectively. Coronary perfusion pressure (CPP) and cortical cerebral blood flow (CCBF) increased and femoral blood flow (FBF) decreased after adrenaline during LabCPR (mean differences (95% CI) CPP 17 (6, 29) mmHg (p = 0.01), FBF -5.0 (-8.8, -1.2) ml min(-1) (p = 0.02) and median difference CCBF 12% of baseline (p = 0.04)). There were no significant effects during ClinicalCPR (mean differences (95% CI) CPP 4.7 (-3.2, 13) mmHg (p = 0.2), FBF -0.2 (-4.6, 4.2) ml min(-1)(p = 0.9) and CCBF 3.6 (-1.8, 9.0)% of baseline (p = 0.15)). Slope VF waveform analysis reflected changes in CPP. CONCLUSION: Adrenaline improved haemodynamics during laboratory quality CPR in pigs, but not with quality simulating clinically reported CPR performance.

Animals↗
PubMed2006

Airway management by paramedics using endotracheal intubation with a laryngoscope versus the oesophageal tracheal Combitube and EasyTube on manikins: a randomised experimental trial.

INTRODUCTION: The EasyTube, which is constructed in a similar way to the Combitube, is a recently introduced alternative to tracheal intubation for airway management in emergency medicine. OBJECTIVE: To determine if there is a difference in rate of, and time to, successful airway placement and ventilation using tracheal intubation, Combitube and EasyTube. METHODS: Twenty-six paramedics, trained in tracheal intubation received additional training in the use of the Combitube and the EasyTube. Each participant performed all three methods twice in random order on a manikin. Time to successful ventilation (presented as mean and standard deviation) and success rate were recorded. RESULTS: Mean time to successful ventilation was significantly longer for tracheal intubation (45.2 s (S.D.=15.8)) than for the Combitube (36.0 s (S.D. = 8.6)) p = 0.002 and the EasyTube (38.0 s (S.D.=15.3)) p = 0.023 with no difference between the latter (p = 1.000). Success rate for the Combitube and EasyTube combined (103/104) was significantly higher than for tracheal intubation (45/52) with odds ratio 16.0 (95% CI: 1.9-134); p = 0.002. CONCLUSION: For paramedics tested on manikins placement success rate was higher with less time required for the Combitube and Easytube than for tracheal intubation with no differences between the Combitube and EasyTube.

Adult↗
PubMed2005

Advanced cardiac life support before and after tracheal intubation--direct measurements of quality.

STUDY HYPOTHESIS: Tracheal intubation should improve the quality of cardiopulmonary resuscitation (CPR) by enabling adequate ventilation without pauses in external chest compressions. METHODS: Out-of-hospital cardiac arrests of all causes were sampled in this non-randomized, observational study of advanced cardiac life support in three ambulance services (Akershus, London and Stockholm). Prototype defibrillators (Heartstart 4000SP, Philips Medical Systems, Andover, MA, USA and Laerdal Medical AS, Stavanger, Norway) registered all chest compressions via an extra chest pad with an accelerometer mounted over the lower part of sternum and ventilations from changes in transthoracic impedance between the standard defibrillator pads. The quality of CPR was analyzed off-line for 119 episodes. Numbers and differences are given as mean +/- S.D. and differences as mean and 95% confidence intervals. RESULTS: Chest compressions were not given in cardiac arrest for 61 +/- 20% of the time before intubation compared to 41 +/- 18% after intubation (difference: 20% (16-24%)). Compressions and ventilations per minute increased from 47 +/- 25 to 71 +/- 23 (difference: 24 (19, 29)) and 5.6 +/- 3.7 to 14 +/- 5.0 (difference: 8.7 (7.6, 9.8)) respectively. Four cases of unrecognized oesophageal intubation (3%) were suspected from the disappearance of ventilation induced changes in thoracic impedance after intubation. CONCLUSION: The quality of CPR improved after tracheal intubation, but the fraction of time without blood flow was still high and not according to international guidelines. On-line analysis of thoracic impedance might be a practicable aid to avoid unrecognized oesophageal intubation, but this area needs further research.

Advanced Cardiac Life Support↗
PubMed2005

Quality of cardiopulmonary resuscitation during out-of-hospital cardiac arrest.

CONTEXT: Cardiopulmonary resuscitation (CPR) guidelines recommend target values for compressions, ventilations, and CPR-free intervals allowed for rhythm analysis and defibrillation. There is little information on adherence to these guidelines during advanced cardiac life support in the field. OBJECTIVE: To measure the quality of out-of-hospital CPR performed by ambulance personnel, as measured by adherence to CPR guidelines. DESIGN AND SETTING: Case series of 176 adult patients with out-of-hospital cardiac arrest treated by paramedics and nurse anesthetists in Stockholm, Sweden, London, England, and Akershus, Norway, between March 2002 and October 2003. The defibrillators recorded chest compressions via a sternal pad fitted with an accelerometer and ventilations by changes in thoracic impedance between the defibrillator pads, in addition to standard event and electrocardiographic recordings. MAIN OUTCOME MEASURE: Adherence to international guidelines for CPR. RESULTS: Chest compressions were not given 48% (95% CI, 45%-51%) of the time without spontaneous circulation; this percentage was 38% (95% CI, 36%-41%) when subtracting the time necessary for electrocardiographic analysis and defibrillation. Combining these data with a mean compression rate of 121/min (95% CI, 118-124/min) when compressions were given resulted in a mean compression rate of 64/min (95% CI, 61-67/min). Mean compression depth was 34 mm (95% CI, 33-35 mm), 28% (95% CI, 24%-32%) of the compressions had a depth of 38 mm to 51 mm (guidelines recommendation), and the compression part of the duty cycle was 42% (95% CI, 41%-42%). A mean of 11 (95% CI, 11-12) ventilations were given per minute. Sixty-one patients (35%) had return of spontaneous circulation, and 5 of 6 patients discharged alive from the hospital had normal neurological outcomes. CONCLUSIONS: In this study of CPR during out-of-hospital cardiac arrest, chest compressions were not delivered half of the time, and most compressions were too shallow. Electrocardiographic analysis and defibrillation accounted for only small parts of intervals without chest compressions.

Aged↗
PubMed2005

Reducing no flow times during automated external defibrillation.

There has recently been an increased attention focused on the importance of reducing time without blood flow from chest compressions (no flow time, NFT) during cardiopulmonary resuscitation (CPR). In this study we have analyzed and quantified the NFTs during external automatic defibrillation in 105 cardiac arrest patients. We found that for around half of the time (about 10 min), these patients were not perfused. We have proposed methods to reduce NFT in connection with analyses and shocks. The key factors were rhythm analysis during ongoing CPR, capacitor charging during analysis, 1 min of CPR immediately after a shock (with rhythm analysis during CPR at the end of the 1 min), and distinguishing between asystole and organized rhythm in analyses to skip pulse check if asystole. The potential reduction in NFT using these methods was calculated theoretically and we found a reduction in the total NFT of about 4.5 and 1 min, respectively, in the subgroups of patients having at least one shock and patients having received no shocks. In the present study, the median NFT ratio could theoretically be reduced from 51% to 34% or 49% to 39% depending on if the patient would have a shockable rhythm or not. By introducing the proposed methods into an AED, the NFT would be significantly reduced, hopefully increasing the survival.

Automation↗
PubMed2005

Independent evaluation of a defibrillation outcome predictor for out-of-hospital cardiac arrested patients.

We evaluated the ability of a previously derived outcome predictor to discriminate between ECG segments corresponding to return of spontaneous circulation (ROSC) or not in validation data from 136 patients with cardiac arrest. The new data used for validation were totally independent from the predictor derivation data used in the original study. Features corresponding to those used in the development of the original outcome predictor, centroid frequency, peak power frequency, spectral flatness and energy, were computed following which a second decorrelated feature set was generated. The outcome predictor was applied to the new data with good correspondence in performance (testing) to what was expected (training) with receiver operator characteristics (ROC) areas of 0.80 and 0.79, respectively. Outcome predictor performance was reproducible. As in the present study, future testing should be performed on totally independent data not included in the design of the outcome predictor to get a reliable impression of expected performance.

Cardiopulmonary Resuscitation↗
PubMed2005

Recommended guidelines for reviewing, reporting, and conducting research on post-resuscitation care: the Utstein style.

The aim of this report is to establish recommendations for reviewing, reporting, and conducting research during the post-resuscitation period in hospital. It defines data that are needed for research and more specialised registries and therefore supplements the recently updated Utstein template for resuscitation registries. The updated Utstein template and the out-of-hospital "Chain of Survival" describe factors of importance for successful resuscitation up until return of spontaneous circulation (ROSC). Several factors in the in-hospital phase after ROSC are also likely to affect the ultimate outcome of the patient. Large differences in survival to hospital discharge for patients admitted alive are reported between hospitals. Therapeutic hypothermia has been demonstrated to improve the outcome, and other factors such as blood glucose, haemodynamics, ventilatory support, etc., might also influence the result. No generally accepted, scientifically based protocol exists for the post-resuscitation period in hospital, other than general brain-oriented intensive care. There is little published information on this in-hospital phase. This statement is the result of a scientific consensus development process started as a symposium by a task force at the Utstein Abbey, Norway, in September 2003. Suggested data are defined as core and supplementary and include the following categories: pre-arrest co-morbidity and functional status, cause of death, patients' quality of life, in-hospital system factors, investigations and treatment, and physiological data at various time points during the first three days after admission. It is hoped that the publication of these recommendations will encourage research into the in-hospital post-resuscitation phase, which we propose should be included in the chain-of-survival as a fifth ring. Following these recommendations should enable better understanding of the impact of different in-hospital treatment strategies on outcome.

Diagnostic Techniques, Cardiovascular↗
PubMed2004

Cardiac arrest and cardiopulmonary resuscitation outcome reports: update and simplification of the Utstein templates for resuscitation registries: a statement for healthcare professionals from a task force of the International Liaison Committee on Resuscitation (American Heart Association, European Resuscitation Council, Australian Resuscitation Council, New Zealand Resuscitation Council, Heart and Stroke Foundation of Canada, InterAmerican Heart Foundation, Resuscitation Councils of Southern Africa).

Outcome after cardiac arrest and cardiopulmonary resuscitation is dependent on critical interventions, particularly early defibrillation, effective chest compressions, and advanced life support. Utstein-style definitions and reporting templates have been used extensively in published studies of cardiac arrest, which has led to greater understanding of the elements of resuscitation practice and progress toward international consensus on science and resuscitation guidelines. Despite the development of Utstein templates to standardize research reports of cardiac arrest, international registries have yet to be developed. In April 2002, a task force of the International Liaison Committee on Resuscitation (ILCOR) met in Melbourne, Australia, to review worldwide experience with the Utstein definitions and reporting templates. The task force revised the core reporting template and definitions by consensus. Care was taken to build on previous definitions, changing data elements and operational definitions only on the basis of published data and experience derived from those registries that have used Utstein-style reporting. Attention was focused on decreasing the complexity of the existing templates and addressing logistical difficulties in collecting specific core and supplementary (ie, essential and desirable) data elements recommended by previous Utstein consensus conferences. Inconsistencies in terminology between in-hospital and out-of-hospital Utstein templates were also addressed. The task force produced a reporting tool for essential data that can be used for both quality improvement (registries) and research reports and that should be applicable to both adults and children. The revised and simplified template includes practical and succinct operational definitions. It is anticipated that the revised template will enable better and more accurate completion of all reports of cardiac arrest and resuscitation attempts. Problems with data definition, collection, linkage, confidentiality, management, and registry implementation are acknowledged and potential solutions offered. Uniform collection and tracking of registry data should enable better continuous quality improvement within every hospital, emergency medical services system, and community.

Adult↗
PubMed2004

Effects of cardiopulmonary resuscitation on predictors of ventricular fibrillation defibrillation success during out-of-hospital cardiac arrest.

BACKGROUND: Early defibrillation is considered the most important factor for restoring spontaneous circulation in cardiac arrest patients with ventricular fibrillation. Recent studies have shown that, after prolonged ventricular fibrillation, the rates of return of spontaneous circulation (ROSC) and survival are improved if defibrillation is delayed so that CPR can be given first. To examine whether CPR improves myocardial readiness for defibrillation, we analyzed whether CPR causes changes in predictors of defibrillation success calculated from the ventricular fibrillation waveform. METHODS AND RESULTS: ECG recordings were retrieved for 105 patients from an original study of 200 patients receiving CPR or defibrillation first. Altogether, 267 CPR sequences from 77 patients were identified on which the effect of CPR could be evaluated. Five predictors of ROSC (spectral flatness measure, energy, centroid frequency, amplitude spectrum relationship, and estimated probability of ROSC) were determined from a spectral analysis of the ventricular fibrillation waveform immediately before and immediately after each of the 267 sequences. CPR increased spectral flatness measure, centroid frequency, and amplitude spectrum relationship (P<0.05, P<0.001, P<0.01). In an analysis of the effect of the duration of CPR, the probability of ROSC and amplitude spectrum relationship showed a positive change for CPR sequences lasting >3 minutes (P<0.001, P<0.05). CONCLUSIONS: During resuscitation from ventricular fibrillation, changes in the predictors calculated from the ventricular fibrillation waveform indicated a positive effect of CPR on the myocardium.

Cardiopulmonary Resuscitation↗
PubMed2004

[Therapeutic hypothermia after cardiac arrest saves more lives!].

To treat patients suffering from cardiac arrest after restoration of spontaneous circulation has been difficult and discouraging, with a high mortality rate. Two independent studies have, however, shown that early treatment with hypothermia increases survival and protects from neurological sequelae after out-of-hospital cardiac arrest. Recently the International Liaison Committee on Resuscitation (ILCOR) has published an advisory statement recommending therapeutic hypothermia after out-of-hospital cardiac arrest. In this paper the issue is discussed and the therapy recommended.

Cardiopulmonary Resuscitation↗
PubMed2004

Rapid extrication from a car wreck.

Extrication of entrapped patients from car accidents takes time. To save time a new technique based on reversing the forces of the original crash by anchoring the rear of the vehicle and pulling the steering wheel and the front window pillars forward with chains is developed. In an experimental randomised trial of extrication of volunteers from car wrecks after frontal/oblique impacts we wanted to evaluate the time spent with a new extrication technique (n=6) compared to standard (n=6). Main outcome measures were time to patient free and to patient on a stretcher. It took significantly longer (s) with the standard than the new technique to start extrication [(60 (45, 70) versus 30 (30, 40), confidence interval (CI) 5-40, P=0.009], to patient free in the front seat [514+/-102 versus 238+/-72, CI 163-389, P=0.001], backboard in place [543+/-102 versus 295+/-76, CI 132-363, P=0.001], and patient on the stretcher ready for transport to the hospital [617+/-112 versus 387+/-65, CI 112-347, P=0.001]. Avoiding uncontrolled movements in the wreck was not more difficult with the new than the standard technique.

Accidents, Traffic↗
PubMed2004

Feasibility of shock advice analysis during CPR through removal of CPR artefacts from the human ECG.

Mechanical activity from chest compressions and ventilations during cardiopulmonary resuscitation (CPR) introduces artefact components into the electrocardiogram (ECG). CPR must therefore be discontinued for reliable shock advice analysis in automated external defibrillators. Reducing or eliminating this detrimental "hands-off" time by removing the CPR artefacts, should significantly improve the defibrillation success rate. The feasibility of this was tested by removing the CPR artefacts using a multichannel adaptive filter, the multichannel recursive adaptive matching pursuit (MC-RAMP) algorithm. Human ECG and reference channel data from episodes with both shockable and non-shockable underlying heart rhythms were recorded from 105 patients with out-of-hospital cardiac arrest. The performance of a shock advice algorithm was evaluated before and after artefact removal using the MC-RAMP algorithm. From a test set consisting of 92 shockable and 174 non-shockable episodes a sensitivity of 96.7% and specificity of 79.9% was achieved, an increase of approximately 15 and 13%, respectively, compared to no filtering. Good sensitivity was achieved, enabling ECG analysis during CPR that would reduce the hands-off time on patients with shockable rhythms. However, CPR artefact removal on non-shockable rhythms proved a more difficult problem. We need a better understanding of the physiological mixing of artefacts and the underlying heart rhythm and suggest clinical trials to investigate the nature of CPR artefacts further.

Algorithms↗
PubMed2004

Cardiac arrest and cardiopulmonary resuscitation outcome reports: update and simplification of the Utstein templates for resuscitation registries. A statement for healthcare professionals from a task force of the international liaison committee on resuscitation (American Heart Association, European Resuscitation Council, Australian Resuscitation Council, New Zealand Resuscitation Council, Heart and Stroke Foundation of Canada, InterAmerican Heart Foundation, Resuscitation Council of Southern Africa).

Outcome following cardiac arrest and cardiopulmonary resuscitation is dependent on critical interventions, particularly early defibrillation, effective chest compressions, and advanced life support. Utstein-style definitions and reporting templates have been used extensively in published studies of cardiac arrest, which has led to greater understanding of the elements of resuscitation practice and progress toward international consensus on science and resuscitation guidelines. Despite the development of Utstein templates to standardize research reports of cardiac arrest, international registries have yet to be developed. In April 2002 a task force of ILCOR met in Melbourne, Australia, to review worldwide experience with the Utstein definitions and reporting templates. The task force revised the core reporting template and definitions by consensus. Care was taken to build on previous definitions, changing data elements and operational definitions only on the basis of published data and experience derived from those registries that have used Utstein-style reporting. Attention was focused on decreasing the complexity of the existing templates and addressing logistical difficulties in collecting specific core and supplementary (i.e., essential and desirable) data elements recommended by previous Utstein consensus conference. Inconsistencies in terminology between in-hospital and out-of-hospital Utstein templates were also addressed. The task force produced a reporting tool for essential data that can be used for both quality improvement (registries) and research reports and that should be applicable to both adults and children. The revised and simplified template includes practical and succinct operational definitions. It is anticipated that the revised template will enable better and more accurate completion of all reports of cardiac arrest and resuscitation attempts. Problems with data definition, collection, linkage, confidentiality, management, and registry implementation are acknowledged and potential solutions offered. Uniform collection and tracking of registry data should enable better continuous quality improvement within every hospital, EMS system, and community.

Adult↗
PubMed2004

Long term survival and costs per life year gained after out-of-hospital cardiac arrest.

PURPOSE: To study long-term survival and estimate the costs per year of survival after out-of-hospital cardiac arrest of cardiac origin. MATERIALS AND METHODS: Cardiac arrest patients treated by the physician-manned ambulance in Oslo from January 1971 to June 1992. The condition of the patient when discharged from hospital was noted and survival followed until June 2002. Costs of the Emergency Medical Service (EMS), hospital treatment, rehabilitation and nursing homes and psychiatric institutions after discharge from hospital were included in a cost-effectiveness analysis. RESULTS: 1300 (42%) of 3065 patients receiving ALS were admitted to hospital after return of spontaneous circulation (ROSC). 1066 of these patients had a cardiac cause of the arrest, full hospital report and were found in the National Registry. Median age was 68 years (60-74) and 802 (75%) were men. 269 of the 1066 patients were discharged from hospital alive, 239 to their homes and 30 patients to rehabilitation/nursing homes or psychiatric institutions. The mean survival of the 1066 patients was 532 days. They spent mean 3.4 days in a CCU, 6.8 days in a general ward and 11.2 days in nursing/rehabilitation homes or psychiatric institutions. 30 patients were discharged to rehabilitation/nursing homes or psychiatric institutions. The mean survival time for the 269 patients discharged from hospital alive was 6.13 years. 110 patients were alive after five and 61 after 10 years. The cost per patient discharged alive was 40,642 or 6,632 per life year gained. CONCLUSIONS: Cardiac arrest patients do not occupy intensive care beds too long, and few end up in a vegetative state. Methodological differences in different studies makes meaningful comparisons of costs difficult, but the costs per life year saved are not high compared to other publications.

Advanced Cardiac Life Support↗