[Big shortages in connection with emergency admissions].
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Emergency Service, Hospital↗
Biomedical subjects
P A Steen
Publications and source records attributed to P A Steen.
[Rescue operations with helicopter ambulances in the Barents sea].
BACKGROUND: Search and rescue helicopters from the Royal Norwegian Air Force conduct ambulance and search and rescue missions in the Barents Sea. The team on board includes an anaesthesiologist and a paramedic. Operations in this area are challenging due to long distances, severe weather conditions and winter darkness. MATERIAL AND METHODS: 147 ambulance and 29 search and rescue missions in the Barents Sea during 1994-99 were studied retrospectively with special emphasis on operative conditions and medical results. RESULTS AND INTERPRETATION: 35% of the missions were carried out in darkness. Median time from alarm to first patient contact was 3.3 hours and median duration of the missions was 7.3 hours. 48% of the missions involved ships of foreign nationality. About half of the patients had acute illness, dominated by gastrointestinal and heart diseases. Most of the injuries resulted from on-board accidents; open or closed fractures, amputations, and soft tissue damage. 90% of the patients were hospitalised; 7.5% would probably not have survived without early medical treatment and rapid transportation to hospital.
Air Ambulances↗
[Ambulance response intervals in connection with cardiac arrest in Oslo].
INTRODUCTION: An important factor determining survival after out-of-hospital cardiac arrest is how fast the ambulance personnel can reach the patient. MATERIALS AND METHODS: In a two-year period between 1996 and 1998, all ambulance calls to patients with out-of-hospital cardiac arrest in Oslo were evaluated. Of 1,026 cardiac arrests, 130 were excluded because of missing data. RESULTS: The median ambulance response interval was 7.2 min (5.7-9.0 as 25-75% percentiles). There was a tendency to shorter response intervals to the central parts of Oslo with medians between 3 and 4 min, while 14 more peripheral boroughs had median response intervals over 8 min. Of the 627 cases where the ambulance starting point was registered, 76% were from the only ambulance station in Oslo, located downtown. INTERPRETATION: In our opinion, the median ambulance response interval is unsatisfactory in large parts of Oslo, as a long response time gives a dramatically lower survival rate after cardiac arrest. A reorganisation and decentralization of the Oslo Emergency Medical Service System seems necessary.
Ambulances↗
Reducing CPR artefacts in ventricular fibrillation in vitro.
CPR creates artefacts on the ECG, and a pause in CPR is therefore mandatory during rhythm analysis. This hands-off interval is harmful to the already marginally circulated tissues during CPR, and if the artefacts could be removed by filtering, the rhythm could be analyzed during ongoing CPR. Fixed coefficient filters used in animals cannot solve this problem in humans, due to overlapping frequency spectra for artefacts and VF signals. In the present study, we established a method for mixing CPR-artefacts (noise) from a pig with human VF (signal) at various signal-to-noise ratios (SNR) from -10 dB to +10 dB. We then developed a new methodology for removing CPR artefacts by applying a digital adaptive filter, and compared the results with this filter to that of a fixed coefficient filter. The results with the adaptive filter clearly outperformed the fixed coefficient filter for all SNR levels. At an original SNR of 0 dB, the restored SNRs were 9.0+/-0.7 dB versus 0.9+/-0.7 dB respectively (P<0.0001).
Animals↗
"Probability of successful defibrillation" as a monitor during CPR in out-of-hospital cardiac arrested patients.
The frequency spectrum of the ECG in ventricular fibrillation (VF) correlates with myocardial perfusion and might predict defibrillation success defined as return of spontaneous circulation (ROSC). The predictive power increases when more spectral variables are combined, but the complex information can be difficult to handle during the intensity of CPR. We therefore developed a method for expressing this multidimensional information in a single reproducible variable reflecting the probability of defibrillation success. This is based on the highest performing predictor for ROSC after 883 shocks given to 156 patients with VF. This was a combination of two decorrelated spectral features based on a principal component analysis of an original feature set with information on centroid frequency, peak power frequency, spectral flatness and energy. The function "Probability of defibrillation success" (P(ROSC)(v)) was developed by a 2-dimensional histogram technique. P(ROSC)(v) discriminated between shocks followed by ROSC and No-ROSC (P<0.0001). The present methodology indicates a possible way to develop a CPR monitor.
Cardiopulmonary Resuscitation↗
Patient autonomy in emergency medicine.
Theoretical models for patient-physician communication in clinical practice are frequently described in the literature. Respecting patient autonomy is an ethical problem the physician faces in a medical emergency situation. No theoretical physician-patient model seems to be ideal for solving the communication problem in clinical practice. Theoretical models can at best give guidance to behavior and judgement in emergency situations. In this article the premises of autonomous treatment decisions are discussed. Based on a case-report we discuss different genuine efforts the physician can do to uncover treatment refusal and respect patient autonomy in an emergency situation. Autonomy requires competence and in emergency medicine time does not allow intimate exploration of patient competence and reasons for treatment refusal. We find that the physician must base her decision on a firm theoretical base combined with a practical and realistic view of the patient's situation on a case to case basis.
Communication↗
Ethics in emergency cardiac care.
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Advance Directives↗
Twenty-four hours of mild hypothermia in unsedated newborn pigs starting after a severe global hypoxic-ischemic insult is not neuroprotective.
Three to 12 h of mild hypothermia (HT) starting after hypoxia-ischemia is neuroprotective in piglets that are anesthetized during HT. Newborn infants suffering from neonatal encephalopathy often ventilate spontaneously and are not necessarily sedated. We aimed to test whether mild posthypoxic HT lasting 24 h was neuroprotective if the animals were not sedated. Thirty-nine piglets (median weight 1.6 kg, range 0.8-2.2 kg; median age 24 h, range 7-48 h) were anesthetized and ventilated and subjected to a 45-min hypoxic (FiO(2) approximately 6%) global insult (n = 36) or sham hypoxia (n = 3). On reoxygenation, 18 were maintained normothermic (NT, 39.0 degrees C) for 72 h, and 21 were cooled from 39 (NT) to 35 degrees C (HT) for the first 24 h before NT was resumed (18 experimental, three sham hypoxia). Cardiovascular parameters and intermittent EEG were documented throughout. The brain was perfusion fixed for neuropathology and five main areas examined using light microscopy. The insult severity (duration in minutes of EEG amplitude < 7 microV) was similar in the NT and HT groups, mean +/- SD (28 +/- 7.2 versus 27 +/- 8.6 min), as was the mean FiO(2) (5.9 +/- 0.7 versus 5.8 +/- 0.8%) during the insult. Six NT and seven HT piglets developed posthypoxic seizures that lasted 29 and 30% of the time, respectively. The distribution and degree of injury (0.0-4.0, normal-maximal damage) within the brain (hippocampus, cortex/white matter, cerebellum, basal ganglia, thalamus) were similar in the NT and HT groups (overall score, mean +/- SD, 2.3 +/- 1.5 versus 2.4 +/- 1.3) as was the EEG background amplitude at 3 h (13 +/- 3.5 versus 10 +/- 3.3 microV). The HT animals shivered and were more active. The sham control group (n = 3) shivered but had normal physiology and neuropathology. Plasma cortisol was significantly higher in the HT group during the HT period, 766 +/- 277 versus 244 +/- 144 microM at 24 h. Mild postinsult HT for 24 h was not neuroprotective in unsedated piglets and did not reduce the number of animals that developed posthypoxic seizures. Cortisol reached 3 times the NT value at the end of HT. We speculate that the stress of shivering and feeling cold interfered with the previously shown neuroprotective effect of HT. Research on the appropriateness of sedation during clinical HT is urgent.
Adult↗
Predicting outcome of defibrillation by spectral characterization and nonparametric classification of ventricular fibrillation in patients with out-of-hospital cardiac arrest.
BACKGROUND: In 156 patients with out-of-hospital cardiac arrest of cardiac cause, we analyzed the ability of 4 spectral features of ventricular fibrillation before a total of 868 shocks to discriminate or not between segments that correspond to return of spontaneous circulation (ROSC). METHODS AND RESULTS: Centroid frequency, peak power frequency, spectral flatness, and energy were studied. A second decorrelated feature set was generated with the coefficients of the principal component analysis transformation of the original feature set. Each feature set was split into training and testing sets for improved reliability in the evaluation of nonparametric classifiers for each possible feature combination. The combination of centroid frequency and peak power frequency achieved a mean+/-SD sensitivity of 92+/-2% and specificity of 27+/-2% in testing. The highest performing classifier corresponded to the combination of the 2 dominant decorrelated spectral features with sensitivity and specificity equal to 92+/-2% and 42+/-1% in testing or a positive predictive value of 0.15 and a negative predictive value of 0.98. Using the highest performing classifier, 328 of 781 shocks not leading to ROSC would have been avoided, whereas 7 of 87 shocks leading to ROSC would not have been administered. CONCLUSIONS: The ECG contained information predictive of shock therapy. This could reduce the delivery of unsuccessful shocks and thereby the duration of unnecessary "hands-off" intervals during cardiopulmonary resuscitation. The low specificity and positive predictive value indicate that other features should be added to improve performance.
Electric Countershock↗
Oxygen toxicity in resuscitation.
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Free Radicals↗
[Guidelines for resuscitation of newborn infants].
This article presents the new guidelines for resuscitation of the newborn from the European Resuscitation Council. It is estimated that, potentially, 800,000 newborns can be saved each year by simple airways manoeuvres. Personnel trained in basic resuscitation should be present at all deliveries and personnel trained in advanced resuscitation at deliveries with known risk factors. Attention to ventilation is of primary importance. Ventilation should be assisted if stimulation does not achieve a prompt onset of spontaneous respiration and/or the heart rate is less than 100 per minute. Chest compressions--1/3 of the anteroposterior diameter of the chest--should be provided if the heart rate is absent or remains < below 60 per minute despite adequate assisted ventilation for 30 seconds. Chest compressions should be coordinated with ventilation at a ratio of 3:1 and a rate of 120 "events" per minute to achieve approximately 90 compressions and 30 rescue breaths per minute. Adrenalin should be given if the heart rate remains below 60 per minute despite 30 seconds of effective ventilation and chest compression.
Apgar Score↗
[Guidelines for cardiopulmonary resuscitation of children].
In this article the European Resuscitation Council's guidelines for basic and advanced resuscitation of children are presented. There are some changes from the previous guidelines. Children are divided in three age categories (in addition to the newly born): children up to one year old, one to eight years old, and more than eight years old. In Norway, but not in the rest of Europe, evaluation of the circulation by pulse check has been eliminated in basic, but not in advanced resuscitation. This is due to reports that pulse checks by lay rescuers require much time with poor specificity and sensitivity. In evaluating the patient's own ventilation, the differentiation between agonal gasps and regular breaths is stressed. ECG monitoring provides the link between paediatric basic life support and advanced life support. The algorithm for the latter closely resembles that proposed for adults. While there were previously three separate algorithms for ventricular fibrillation/ventricular tachycardia, asystole and electromechanical dissociation, there is now only one algorithm. Ventilation and chest compressions should be performed for one-minute periods with ventricular fibrillation/ventricular tachycardia, for three-minute periods with other rhythms.
Adult↗
Perfusion magnetic resonance imaging of the lung: characterization of pneumonia and chronic obstructive pulmonary disease. A feasibility study.
Perfusion magnetic resonance (MR) imaging is a promising new method for detection of perfusion defects in the diagnosis of pulmonary embolism. In the present study we evaluated the first-pass characteristics of perfusion MR imaging in patients with pneumonia or chronic obstructive pulmonary disease (COPD), frequent differential diagnoses to pulmonary embolism. Dynamic contrast-enhanced MR images of 12 patients with acute pneumonia and 13 patients with exacerbation of COPD were acquired in both the coronal and transaxial planes (an inversion recovery prepared gradient-echo sequence using 0.05 mmol/kg gadodiamide/injection). The MR images and the signal intensity (SI) versus time curves were characterized for each disease entity and compared with normal lung and the findings in pulmonary embolism from our previous study. The perfusion MR images of pneumonia showed distinct regions of increased contrast enhancement; in COPD with signs of emphysema (11 of the 13 COPD patients), the images showed a coarse pattern of reduced contrast enhancement. The SI versus time curves of pneumonia, COPD with signs of emphysema, and normal lung were statistically different, the respective pooled SI values (+/-95% CI) being as follows: mean baseline SI, 20.7 (1.1), 7.4 (0.4), and 8.5 (0.3); mean peak SI, no peak, 12.9 (1.5), and 27 (4.6); and mean max change of SI in percent, 110 (27), 79 (22), and 205 (52). Perfusion MR imaging of pneumonia and COPD with signs of emphysema showed first-pass that were characteristics promising for diagnostic use. Both the MR images and the SI versus time curves were different from the perfusion characteristics in normal lung and pulmonary embolism shown previously.
Contrast Media↗
Airway pressure with chest compressions versus Heimlich manoeuvre in recently dead adults with complete airway obstruction.
In a previous case report a standard chest compression successfully removed a foreign body from the airway after the Heimlich manoeuvre had failed. Based on this case, standard chest compressions and Heimlich manoeuvres were performed by emergency physicians on 12 unselected cadavers with a simulated complete airway obstruction in a randomised crossover design. The mean peak airway pressure was significantly lower with abdominal thrusts compared to chest compressions, 26.4+/-19.8 cmH(2)O versus 40.8+/-16.4 cmH(2)O, respectively (P=0.005, 95% confidence interval for the mean difference 5.3-23.4 cmH(2)O). Standard chest compressions therefore have the potential of being more effective than the Heimlich manoeuvre for the management of complete airway obstruction by a foreign body in an unconscious patient. Removal of the Heimlich manoeuvre from the resuscitation algorithm for unconscious patients with suspected airway obstruction will also simplify training.
Adult↗
Arterial blood-gases with 500- versus 1000-ml tidal volumes during out-of-hospital CPR.
The correct tidal volume during cardiopulmonary resuscitation (CPR) is presently debated. While the European Resuscitation Council (ERC) and American Heart Association (AHA) previously recommended a tidal volume of 800-1200 ml, the ERC has recently reduced this to 400-600 ml. In a prospective, randomised study of 17 non-traumatic out-of-hospital cardiac arrest patients intubated and mechanically ventilated 12 min(-1) with 100% oxygen, we have therefore compared arterial blood gases generated with tidal volumes of 500 and 1000 ml. Mean time from cardiac arrest to arrival of the ambulance was 13+/-8 and 14+/-8 min in the two groups, respectively. Arterial blood samples were taken percutaneously 5 and 10-15 min after onset of the mechanical ventilation and analysed instantly. Pa(CO(2)) was significantly higher for a tidal volume of 500 than 1000 ml at both 5 and 10-15 min, 7.48+/-2.23 versus 3.70+/-0.83 kPa (P=0.002) and 7. 45+/-1.19 versus 3.98+/-1.58 kPa (P<0.001). The pH was lower for 500 than 1000 ml at 10-15 min, 7.01+/-0.10 versus 7.20+/-0.17 (P=0.034), with a strong trend in the same direction at 5 min (P=0.06). There was adequate oxygenation with no differences in Pa(O(2)) or BE at any time between the two groups, and no significant differences in any blood gas variables between the 5- and 10-15-min samples. We conclude that arterial normocapnia is not achieved with either tidal volume during advanced life support with non-rebreathing ventilation at 12 min(-1). What ventilation volume is required for CO(2) removal and oxygenation during basic life support with mouth-to-mouth ventilation cannot be extrapolated from the present data. In that situation the risk of gastric inflation, regurgitation and aspiration must also be taken into account.
Aged↗
New recommendations for uniform reporting of data following major trauma: "the Utstein style".
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Documentation↗
Bispectral index, predicted and measured drug levels of target-controlled infusions of remifentanil and propofol during laparoscopic cholecystectomy and emergence.
BACKGROUND: Target-controlled infusions (TCI) have been launched as simple, accurate and reliable delivery systems of intravenous drugs. Bispectral index of EEG (BIS) seems promising in measuring hypnotic effect of anaesthetic drugs. The aims of this study were to evaluate the accuracy of TCI systems in patients undergoing laparoscopic cholecystectomy and to correlate measured drug levels to BIS values. Data were analysed for possible gender differences during emergence. METHODS: After written informed consent, 20 patients were enrolled in an open study. Remifentanil was set at 7.5 ng/ml as target throughout the whole procedure, and propofol at 5 microg/ ml at induction and 3 microg/ml after intubation. Values in blood samples of remifentanil and propofol were correlated to the estimated values and to systolic blood pressure and BIS. BIS values and measured drug levels during emergence and emergence time were compared for the two sexes. RESULTS: Measured drug values varied considerably from the set target with a prediction error of -22% for remifentanil and 49% for propofol. The anaesthesia level was regarded as quite deep with a mean BIS during stable surgery of 42 +/- 7, and at this level we found no correlation between measured values of either of the two drugs and BIS. The emergence time was significantly shorter for women (12.6 +/- 2.5 min) than for men (19.0 +/- 4.2 min) (P=0.001), with no significant differences in measured levels of propofol or remifentanil or BIS during the emergence period. CONCLUSION: Present systems for TCI of remifentanil and propofol result in large intra- and interindividual variations in measured drug levels, and measured levels differ from target. There may be possible interaction between the two anaesthetics at a pharmacokinetic level. Within the level of anaesthesia studied here, BIS was not an indicator of the actual drug levels. Women woke up significantly faster than men.
Adult↗
Efficiency of activation of the trauma team in a Norwegian trauma referral centre.
OBJECTIVE: To evaluate the efficiency (sensitivity, specificity, positive predictive value, overtriage, and undertriage) of activation of the trauma team in a Norwegian trauma referral centre. DESIGN: A cohort study with univariate and multivariate analysis. SETTING: A primary trauma hospital and trauma referral centre, Norway. SUBJECTS: 3391 injured patients admitted during a 12 months period, starting January 15th, 1996. MAIN OUTCOME MEASURES: Activation of the trauma team for severely injured patients and factors associated with correct activation. RESULTS: Of the 3383 injured patients admitted, 283 (8%) were classified as severely injured. Of 507 activations of the trauma team, 240 (47%) were for severely injured patients (sensitivity 85%, undertriage 15%, specificity 91%, overtriage 9%, positive predictive value 0.47). The system of activation was significantly more efficient for patients admitted by anaesthetist-manned ambulances than by ordinary ground ambulances (sensitivity 94% compared with 83%, corresponding positive predictive value 0.55 and 0.33, p < 0.05). Female sex and age over 70 years were independent factors associated with significantly less use of the trauma team in severely injured patients (p < 0.05). CONCLUSION: The undertriage rate of 15% and a positive predictive value of only 0.47 indicates a need for improvement of our activation system. Female sex and age over 70 years were significantly associated with undertriage in severely injured patients. Our protocol for triage and the initial treatment of severely injured patients has been revised in the light of these findings, and we have established a trauma registry.
Adolescent↗