[Add-on-LUCAS2™ resuscitation at NEF Innsbruck]

Studienziel

Ziele sind die Verlaufsanalyse und der Vergleich mit ausschließlich manuell reanimierten Patienten sowie die Erfassung der Einflussfaktoren bei Patienten, bei denen die mechanische Thoraxkompressionshilfe Lund University Cardiac Assist System (LUCAS2^TM) als Add-on-Therapie am Notarzteinsatzfahrzeug (NEF) Innsbruck verwendet wurde.

Material und Methodik

Retrospektive Verlaufsdatenanalyse von Patienten im Studienzeitraum 01.01.2014 bis 31.12.2019 des NEF Innsbruck aus dem Deutschen Reanimationsregister (GRR), bei denen LUCAS2™ nach notärztlicher Anordnung als Add-on-Therapie verwendet wurde.

Ergebnis

Bei 653 Reanimationen kam es zu 123 Add-on-LUCAS2™-Anwendungen (18,8 %). Von allen Patienten überlebten 16,2 % die ersten 30 Tage. Mithilfe der Add-on-LUCAS2^TM Anwendung überlebten 7,3 % (9/123) aller Add-on-LUCAS2™-Reanimationen bzw. 1,4 % (n = 9) aller CPRs. Bei 8/9 Add-On-LUCAS2™-„30 Tage-Überlebenden“ war der Herz-Kreislauf-Stillstand (HKS) beobachtet, und eine Laien-CPR wurde durchgeführt. Als Primärrhythmus wiesen 8/9 Kammerflimmern auf.

Im Vergleich zur ausschließlich manuellen CPR wurde eine Add-on-LUCAS2™-Reanimation hoch signifikant (p < 0,001) häufiger bei jüngeren, bei männlichen Patienten, in der Öffentlichkeit, bei schockbarem Erstrhythmus und beim Transport eingesetzt sowie signifikant häufiger bei beobachteten HKS (p < 0,05).

Die 30-Tage-Mortalität bei additiver Lysetherapie betrug 100 %.

Diskussion

Durch die Verwendung der Add-on-LUCAS2™-CPR kann eine prozentuelle Erhöhung der Überlebensrate erzielt werden und erscheint somit vorteilhaft (1,4 % in dieser Studie). Durch diese kann bei Patienten mit günstigen Prognosefaktoren eine hochwertige HDM auch bei technisch aufwendiger Bergung (Drehleiter, Stiegenhaus, Transport im RTW) durchgeführt und somit ein Transport ermöglicht werden. Jedoch kommt es dabei zu einer höheren Aufnahmerate unter CPR und somit zur Verlagerung der Therapiezielentscheidung in den Schockraum.

[Evaluation of cancelled emergency physician missions and patient handovers in the area of Innsbruck : Retrospective assessment of physician-staffed emergency medical service cancellations and handovers from the emergency physician to the emergency medical service in 2017 and 2018]

BACKGROUND

Human and vehicle resource management indicates a good emergency medical system (EMS). Frequently, an emergency medical technician (EMT) is the first responder to the emergency, which negates the necessity for an emergency physician (EP) and is just as sensible as handing over a stable patient to the EMT for transport to the hospital. The Austrian EMS is utilized by EMTs, in cases of potential life-threatening emergencies the dispatch center dispatches an additional team with an on-board EP. During the years 2017-2018 nearly every fifth EP mission in Innsbruck (including surrounding areas) ended in a cancellation. The numbers of patient handovers from EP to EMT are slightly lower with mission cancellations resulting in every fourth patient. Therefore, due to the high number of cancellations and handovers evaluated in this study, the findings suggest that there is a potential need to re-evaluate procedures. The re-evaluation of these procedures could determine whether these cancellations/handovers were justified or if an over hasty decision making was at fault. All cases considered in this study were from the Innsbruck and Telfs EP bases between 1 January 2017 and 13 December 2018.

METHODS

Out of a total of 96,908 emergency dispatches, there were 2470 cancellation/handover occurrences. These occurrences consisted of 1190 cancellations and 1280 patient handovers from the EP to the EMT. Patients who were transferred to the University Hospital Innsbruck were included in these figures. The protocols of the emergency dispatches have been filtered from the so-called CarPC. They have subsequently been grouped into cancellation and handover categories. The clinical diagnoses of the patients with inpatient treatment were evaluated from the hospital information system (KIS) of the University Hospital Innsbruck. This was done with the help of the so-called emergency physician indications catalogue of the German Medical Council. The diagnosis was documented in the hospital information system. The emergency protocols from the EMTs were also evaluated retrospectively. The Innsbruck based EP patients are hospitalized in the Innsbruck Hospital due their geographical position. When there is no need for a specific intervention the patients of the EPs based in Telfs are transferred to a local hospital. When a specific intervention is necessary, patient care must be provided by the University Hospital Innsbruck. Due to the privacy practices of the Innsbruck Medical University "vote of ethics" only the data of patients transferred to the Innsbruck Clinic can be evaluated. The information provided from the EPs based in Innsbruck was exclusively from the University Hospital Innsbruck's anesthesiologists. The physicians from the Telfs EP base are of mixed medical specialities. All of them, however, have an emergency medical physician diploma, in addition to the ius practicandi. Lastly, there are no EPs in Innsbruck or Telfs, who have any special obligations during their duty.

RESULTS

The results show that in 210 cases (8.5%) the indications for the EP, based on the emergency physician indications catalogue of the German Medical Council were given. Also, 8.7% of all cancellations and 8.4% of patient handovers were not justified. Patients with emergency indications had a longer hospitalization. The EP base EMS Innsbruck had more cancellations than the EP base EMS Telfs. The EMS Innsbruck also had more cancellations than patient handovers. Conversely, the EMS Telfs had more patient handovers than cancellations. On the weekends between 6:00 pm and 6:00 am there were less cancellations and handovers from both EP bases. The documentation from the EMT protocols was incomplete in 284 cancellations (23.9% of the cancellations) and 339 handovers (26.5% of the handovers), 35 patients after cancellations (2.9%), 35 patients after handovers (2.7%) needed intensive care treatment, 20 patients after cancellations (1.7% of all cancellations), and 24 patients after handovers (1.9% of all handovers) who needed intensive care treatment had a critical diagnosis. In 40 cases of patient handovers, the EP was alerted to another emergency follow-up within 10 min.

CONCLUSION

In Austria, the introduction of a standardized emergency indication checklist might help dispatch centers to provide a more accurate dispatch as well as all EMS team members. Furthermore, a better traceability system (according to EP cancellations and patient handovers from the EP to the EMT) could be achieved. The documentation requirements should be more precise by all members of the EMT staff, not only for the legal aspects but also for improving the overall management quality. Intense education and training as well as diagnosis feedbacks could help to reduce the number of risky cancellations/patient handovers.

Assessment of reperfusion following thrombolysis with mean fibrillation and amplitude spectrum area in patients with sustained ventricular fibrillation

BACKGROUND

Improved microcirculatory reperfusion in patients with ventricular fibrillation (VF) enhances the electrical activity of the fibrillation process and increases the likelihood of successful defibrillation.

METHODS

Changes in amplitude spectrum area (AMSA) and mean fibrillation (MF) in patients with sustained VF were analysed after administration of rt-PA variant tenecteplase in out-of-hospital cardiac arrest (OHCA) during cardiopulmonary resuscitation (CPR).

RESULTS

A total of 69 ECG sequences from nine patients were evaluated. Patients who received tenecteplase showed significantly longer duration of VF (p = 0.016). While AMSA declined significantly during CPR (p = 0.001), MF did not differ between groups. There were two survivors in the treatment group and one in the control group.

CONCLUSION

When tenecteplase was administered during CPR, VF lasted significantly longer than in controls. Changes in MF and AMSA did not indicate improved myocardial perfusion in patients who received tenecteplase during CPR.

Recombinant tissue plasminogen activator during cardiopulmonary resuscitation in 108 patients with out-of-hospital cardiac arrest

BACKGROUND

Thrombolytic therapy during cardiopulmonary resuscitation (CPR) is a controversial issue in emergency medicine practice. This study was conducted to determine whether administration of recombinant tissue plasminogen activator (rt-PA) in out-of-hospital cardiac arrest of non-traumatic aetiology improves CPR outcome.

METHODS AND RESULTS

A retrospective chart review of 401 patients with out-of-hospital cardiac arrest who were resuscitated by the emergency medical services (EMS) during a 6 year period was performed. A total of 108 patients received rt-PA during CPR and were compared to 216 controls, closely matched according to baseline characteristics, arrival status and ECG findings. Administration of rt-PA was optional. Return of spontaneous circulation (ROSC) occurred in 76 patients under rt-PA treatment (70.4 vs. 51.0% in controls; P=0.001). Fifty-two patients from the lysis group survived the first 24 h (48.1 vs. 32.9% in controls; P=0.003), while 27 (25.9%) survived to discharge. Autopsy reports revealed major bleeding complications in six patients receiving rt-PA treatment. Fulminant intracranial haemorrhage was observed in one patient who received rt-PA and in two cases from the control group.

CONCLUSIONS

Thrombolytic therapy may improve frequency of return of spontaneous circulation substantially and increase primary survival in patients with non-traumatic cardiac arrest. Serious bleeding complications are not frequently observed under rt-PA treatment.

Waveform analysis of biphasic external defibrillators

BACKGROUND AND OBJECTIVE

All internal defibrillators and some external defibrillators use biphasic waveforms. The study analysed the discharged waveform pulses of two manual and two semi-automated biphasic external defibrillators.

METHODS AND RESULTS

The defibrillators were discharged into resistive loads of 25, 50 and 100 Omega simulating the patient's transthoracic impedance. The tested biphasic defibrillators differed in initial current as well as initial voltage, varying from 10.9 to 73.3 A and from 482.8 to 2140.0 V, respectively. The energies of the manual defibrillators set at 100, 150 and 200 J deviated by up to +19.1 or -28.9% from the selected energy. Impedance-normalised delivered energy varied from 1.0 to 12.5 J/Omega. Delivered energy, shock duration and charge flow were examined with respect to the total pulse, its splitting into positive and negative phases and their impedance dependence. For three defibrillators pulse duration increased with the resistive load, whereas one defibrillator always required 9.9 ms. All tested defibrillators showed a higher charge flow in the positive phase. Defibrillator capacitance varied between approximately 200 and 100 mu F and internal resistance varied from 2.0 to 7.6 Omega. Defibrillator waveform tilt ranged from -13.1 to 61.4%.

CONCLUSIONS

The tested defibrillators showed remarkable differences in their waveform design and their varying dependence on transthoracic impedance.

Measuring forces and frequency during active compression decompression cardiopulmonary resuscitation: a device for training, research and real CPR

Active compression decompression (ACD) cardiopulmonary resuscitation (CPR) is possibly a superior alternative to standard (STD) CPR, but an optimal compression and decompression pattern has to be ensured. ACD-CPR can be evaluated during CPR training sessions using commercially available manikins; however devices for recording compression and decompression forces or frequency during real CPR are lacking. Using the Ambu CardioPump without changing its mechanical characteristics, two force transducers were integrated into the ACD device. Using specially designed electronics and a portable computer, compression and decompression forces were measured and displayed continuously and compression frequency and the compression decompression phase are calculated on-line during real CPR action. All measured parameters were stored on a hard disk for later retrieval and analysis. Linearity of force measurement was better than 6% within a -250- +500 N range. The error in repeatability was below 5% thus outperforming the original mechanical force measurement system of the Ambu CardioPump. Compression frequency was calculated very accurately (error < 1%). The system has been successfully used during CPR training, during ACD-CPR in 37 corpses under research conditions and in five out-of-hospital CPR casualties. Simple and safe in use, our modified CardioPump with integrated electronics provides an important, technically advanced solution for monitoring ACD-CPR on-line. It warrants quality assurance during ACD-CPR training and in real CPR scenarios and guarantees accurate recording of compression and decompression forces and compression frequency.

Chest injuries after active compression-decompression cardiopulmonary resuscitation (ACD-CPR) in cadavers

In a prospective study of 38 cadavers of patients older than 18 without previous chest injury or cardiopulmonary resuscitation (CPR), active compression-decompression (ACD) resuscitation manoeuvres were performed to determine possible factors influencing sternal and/or rib fractures. ACD was performed for 60 s, with compression and decompression forces being continuously recorded. A stepwise logistic regression analysis was applied. Factors analyzed were age, gender, use of a compression cushion beneath the piston of the ACD device (Ambu CardioPump), and maximal compression and decompression forces. After ACD, the cadavers were autopsied and thoracic injuries were assessed. There was a significant correlation between sternal fractures and gender (P = 0.008), and between rib fractures and age (P = 0.008). Women were found to have a higher risk for sternal fractures, whereas older patients had a higher risk for rib fractures. Maximal compression force was another factor in sternal and/or rib fracture (P = 0.048). Even though a significantly higher incidence of sternal fractures was observed when the compression cushion was used (P = 0.045), inclusion of this variable in the regression analysis only marginally improved the prediction for correct classification of sternal fractures. In conclusion, when well controlled ACD-CPR is performed in cadavers, age is the most important factor determining the incidence of rib fracture. Sternal fractures were more common in female cadavers.

Waveforms of external defibrillators: analysis and energy contribution

BACKGROUND AND OBJECTIVE

Defibrillation is the most important therapy for terminating ventricular fibrillation in cardiac arrest patients. In addition to performing defibrillation at the earliest possible time, appropriate pulse energy and optimal waveform seem to be crucial for success. Emergency medical service personnel use different defibrillators and rely on their similarity of energy content. This study examined the true pulse energy content and waveform of 17 commonly used defibrillators.

METHODS AND RESULTS

Defibrillation energies were selected to be 30, 200 or 360 J and defibrillators were discharged into test resistors, simulating transthoracic impedances of 25, 50 or 100 Ohms. Pulse energy deviated by up to +23% or -29% from the selected energy. Pulse energy within the initial 8 ms ranged from 90 to 30% of total pulse energy. Fourteen defibrillators utilising damped sinusoidal waveforms produced a monophasic pulse when discharged into resistances of 50 Ohms and 100 Ohms.

CONCLUSIONS

Defibrillators used at the same energy settings do not necessarily produce the same defibrillation pulse energy. All but one defibrillator actually use monophasic waveforms, leaving the potential advantage of biphasic waveforms unused. Energy accuracy of defibrillators needs to be improved, and biphasic waveforms should be used more.

Increased frequency of thorax injuries with ACD-CPR

A prospective, randomised out-of-hospital study in a two-tiered system with active compression-decompression (ACD) cardiopulmonary resuscitation (CPR) versus standard (STD) CPR in patients following non-traumatic cardiac arrest was planned to test the hypothesis that ACD-CPR by the first tier may increase the occurrence of ventricular fibrillation as compared with STD-CPR. Furthermore, in a later phase of the study, sternal and rib fractures induced by both CPR methods were determined by extensive autopsy. After enrolling 90 patients the study was terminated because of a high frequency of chest injuries found at autopsy. Forty-two patients received STD-CPR from the first tier and ACD-CPR from the second tier. Thirty-three patients received ACD-CPR only by the first and the second tier, while 15 patients received STD-CPR only from the first and second tiers. In order to obtain a sufficiently large control group for autopsy findings after STD-CPR, STD-CPR was performed in an additional 33 patients within a second period of 4 months. There was no improvement in the number of patients found in ventricular fibrillation after ACD-CPR as compared to STD-CPR performed by the first tier. In patients undergoing autopsy (n = 35) there were significantly more sternal fractures with ACD-CPR versus STD-CPR (14/15 vs. 6/20; P <0.005) and rib fractures (13/15 vs. 11/20; P < 0.05) In conclusion, ACD-CPR appears to cause more CPR-related injuries than does standard CPR, but as a result of a number of limitations on this study, this fact cannot be proven beyond doubt.

Forward blood flow during cardiopulmonary resuscitation in patients with severe accidental hypothermia. An echocardiographic study

BACKGROUND

The mechanism responsible for the forward blood flow associated with external chest compression is still controversial. Evidence for both blood flow caused by direct cardiac compression and blood flow generated by a general increase in intrathoracic pressure has been found in experimental as well as clinical studies. No data are available concerning the mechanism causing forward blood flow in hypothermic patients undergoing cardiopulmonary resuscitation. Therefore, echocardiographic findings during external chest compression in seven hypothermic arrest victims are reported.

METHODS

All transesophageal echocardiographic studies performed at the Anaesthesia department between 1994 and 1997 were reviewed and seven hypothermic patients with transesophageal echocardiography performed during cardiopulmonary resuscitation were identified.

RESULTS

An open mitral valve or a circumferential reduction in aortic diameter during the compression phase was found in four of seven patients, indicating that primarily an increase in intrathoracic pressure (thoracic pump mechanism) generated forward blood flow. In three patients, mitral valve closure during external chest compression indicated that direct cardiac compression (cardiac pump mechanism) contributed to forward blood flow. Two patients studied during active compression-decompression cardiopulmonary resuscitation demonstrated enhanced right ventricular filling and aortic valve opening during active decompression of the thorax.

CONCLUSIONS

In contrast to normothermic arrest victims, an open mitral valve during external chest compression is a common finding during hypothermia, indicating that thoracic pump mechanism is important for forward blood flow during cardiopulmonary resuscitation in hypothermic arrest victims. Aortic valve opening in two hypothermic arrest victims suggests forward blood flow also during active decompression of the thorax with the Cardiopump.

Force distribution across the heel of the hand during simulated manual chest compression

According to most published guidelines of cardiopulmonary resuscitation chest compression is performed on the lower half of the sternum by compressing the sternum with the heel of one hand and the other hand on top of the first. In all guidelines and during CPR training great importance is attributed to exact localisation of the so-called compression point. In a laboratory investigation we assessed the force distribution across the heel of the hand and defined the total breadth in contact with the sternum. In order to find out whether there is any difference in the force pattern with the right or the left hand in direct contact with the sternum we determined the resultant maximal force of that part of the heel of the hand exerting the maximal force. A total of 12 anaesthetists performed simulated chest compressions onto a flat surface covered with an integrated force sensor mat. The distance between the most ulnar part and the most radial part of the hand was determined to be 9.2 cm. Similar mean total forces were measured (right hand in contact: 644 N; left hand in contact: 621 N). In all except one anaesthetist the hypothenar part of the heel exerted a significantly higher force compared to the thenar part, independent of whether the right hand or the left hand was in contact. The distance between points of maximal force when the right hand or when the left hand in contact was 2.2 cm corresponding to the breadth of one and a half fingers. To reduce the potential risk of sternal fractures by chest compressions applied too far in a cephalad direction, we recommend use of the right hand in contact if the rescuer kneels at the right side of the patient and vice versa.

Review of active compression-decompression cardiopulmonary resuscitation (ACD-CPR). Analysis of iatrogenic complications and their biomechanical explanation

Our review takes a critical look at the active compression-decompression technique (ACD) for cardiopulmonary resuscitation (CPR). ACD-CPR was developed following a report of successful resuscitation performed by a medical amateur using a household plunger. The efficacy of the principle of active decompression has been demonstrated by animal and human studies. Potential iatrogenic complications from the CardioPump were evaluated only when large clinical trials were already underway. Our prospective analysis of autopsy patients and systematic randomised studies in corpses prove that ACD-CPR using the CardioPump considerably increases the rate of iatrogenic complications and especially of sternum fractures. The experimental use of the CardioPump in corpses and the analysis of a variety of different parameters, especially of the rubber cushion pads mounted in the silicone cup to prevent skin abrasions, revealed a statistically significant correlation between sternum fractures and female sex (P < 0.01) and usage of the rubber cushion pad (P = 0.045). Biomechanical studies showed that the transmission of forces from the CardioPump is greatly dependent on chest shape. The lower the sternum is sunken compared with the surrounding structures, the higher the force which is transmitted via the central area of the device onto the sternum. The rubber cushion pad shortens the distance between CardioPump and sternum by 5 mm and therefore increases the sternal loading. Sex differences in the shape of the sternum and especially the thickness may account for the significant correlation between sternum fractures and female sex.

The prognostic significance of coma-rating, duration of anoxia and cardiopulmonary resuscitation in out-of-hospital cardiac arrest

Early determination of outcome after successful prehospital cardiopulmonary resuscitation (CPR) is a common problem with great ethical, economic, social, and legal consequences. We prospectively investigated 112 adult patients who had been resuscitated after out-of-hospital cardiac arrest (CA). The aim of our study was to determine whether coma rating by the mobile intensive care unit (MICU) is a useful tool for outcome prediction. For neurological assessment the Innsbruck Coma Scale (ICS) was used initially and after return of spontaneous circulation (ROSC) or 20-30 min after the start of CPR, before any sedating drugs were given. The duration of anoxia and CPR were determined with the automatically recorded emergency call protocol of the dispatch centre and the protocol of the MICU. For estimation of cerebral outcome at the time of discharge from hospital we used the Glasgow-Pittsburgh Cerebral Performance Categories (CPC). Restoration of spontaneous circulation was achieved in 42 patients (37%), and 15 (13%) were discharged from hospital. The first coma rating performed immediately at the time of arrival on scene had no significant prognostic value for prediction of neurological outcome (P = 0.204) and survival (P = 0.103). The second coma rating (performed after ROSC or 20-30 min after the start of CPR), however, demonstrated a significant correlation with neurological outcome (P = 0.0000) and survival (P = 0.0000), a correlation which was comparable to both duration of anoxia and duration of CPR. In patients with out-of-hospital cardiac arrest prognostic information could be obtained with the ICS as early as 20-30 min after the start of cardiopulmonary resuscitation.

Active compression-decompression resuscitation: the influence of different chest geometries on the force transmission

Active compression-decompression cardiopulmonary resuscitation (ACD-CPR) is performed using a plunger-like suction device applied onto the chest. Forces are partly transferred through the center of this device as well as through the peripheral ring of the plunger's lip seal. We analysed the load transmission distribution of the Ambu CardioPump; therefore a homemade mechanical model was used for simulating different chest geometries. We applied compression forces up to 750N on the device using a 'material testing machine', and we determined the load transferred through the central part of the device and the peripheral ring respectively. The results show that the deeper the sternum is inbeded in the chest the more force is distributed onto the peripheral ring of the plunger's vacuum cup. For a simulated flat chest, 70 N was transferred through the peripheral ring; at a simulated sternal depression of 20 mm, more than 300 N were transferred peripherally. This study points out that different chest geometries have to be considered when using CardioPump.

Active compression-decompression cardiopulmonary resuscitation in standing position over the patient: pros and cons of a new method

Active compression-decompression cardiopulmonary resuscitation (ACD-CPR) has been introduced to improve outcome of CPR after cardiac arrest. Usually, ACD-CPR is performed with the rescuer kneeling beside the patient (ACD-B), but ACD-CPR with the rescuer in standing position (ACD-S) has been taught and applied in some centres in addition to conventional ACD-CPR (ACD-B). The aim of this randomised and cross-over study was to evaluate the new technique of ACD-S and to compare it with conventional ACD-B. Twelve professional rescuers (aged 30.8 +/- 7.9 years) applied both methods of ACD-CPR on a manikin. We obtained the following results. (1) Duration of CPR performance was comparable for ACD-S (13.2 +/- 7.1 min) and ACD-B (15.5 +/- 10.2 min, P = 0.48). (2) Pain in the upper extremity and pain in the vertebral column were the main reasons for break-off by the rescuers. Exhaustion was judged to be similar during ACD-S (5.3 +/- 2.3) and ACD-B (6.2 +/- 2.1; on a rating scale with 1 = no and 9 = complete exhaustion). (3) Oxygen consumption was significantly higher during ACD-S (P < 0.005), whereas heart rate and lactate levels did not differ. (4) Decompression forces were lower than compression forces. The averaged decompression forces in both methods were similar during the first 2 min and the last min. Compression forces decreased in ACD-S from 55.1 to 48.9 kp (P = 0.002) and in ACD-B from 52.8 to 47.0 kp (P = 0.069). We conclude that ACD-CPR in standing position can be considered equal to ACD-B in view of maximal duration of CPR, exhaustion of the rescuers and decompression forces. The decrease of compression forces in ACD-S and ACD-B as well as the difference between compression forces in ACD-S and ACD-B seem to be of no clinical relevance, and exhaustion was judged to be similar despite oxygen consumption being higher in ACD-S than in ACD-B.

Rescuer's work capacity and duration of cardiopulmonary resuscitation

Specific training in the techniques of cardiopulmonary resuscitation (CPR) has been the major aim of CPR education for both health care professionals and lay people over the past few decades. We performed a randomized trial to evaluate individual physiological parameters of 12 professional rescuers influencing duration and quality of standard CPR and active compression-decompression CPR. CPR duration was assessed according to individual work capacity after grouping rescuers as untrained and trained individuals, according to their work capacity of up to and including 100% and over 100%. The average work capacity of all the rescuers was determined by incremental exercise testing, resulting in 110.0 +/- 26.5% compared with data for the normal population. With 29.3 +/- 12.8 min duration, standard CPR was significantly longer than active compression-decompression CPR with 15.5 +/- 10.2 min duration (P = 0.009). No changes in the forces of compression and decompression were measured during active compression-decompression CPR, thus demonstrating maintenance of constant CPR quality. Duration of resuscitation was influenced by the CPR method performed and by the individual work capacity (P = 0.004 and P = 0.027, respectively). We conclude that the duration of CPR depends both on the method applied and the rescuers' individual work capacity and recommend improvement of work capacity by aerobic training especially for professional rescuers.

Active compression-decompression cardiopulmonary resuscitation--instructor and student manual for teaching and training. Part I: The workshop

In an attempt to standardize the teaching and training of active compression-decompression cardiopulmonary resuscitation (ACD-CPR), a group of leading emergency physicians, cardiologists, anesthesiologists, paramedics and nurses with practical, theoretical, educational, and scientific experience in the subject met in June 1995. The group was called The International Working Group of Teaching and Training Active Compression-Decompression CPR. The group was 'born' as a result of the first International Conference of Active Compression-Decompression CPR held in Copenhagen in March 1995. The following paper describes the background, development and text of and ACD-CPR course manual for both students and instructors.

Serious complications from active compression-decompression cardiopulmonary resuscitation

Complications arising from techniques of cardiopulmonary resuscitation (CPR) were reviewed by analysing the autopsy protocols of 25 patients who died after standard (Std) CPR and 31 who died after active compression-decompression (ACD) CPR, 15 of them preceded by Std CPR. The results can be summarised as follows: After Std CPR (n = 25) rib fractures were detected in 28%, sternal fractures in 16%, and no injuries in 68%. After ACD-CPR (n = 16) rib fractures occurred in 68%, sternal fractures in 68% and no injuries in 25%. After ACD-CPR following Std CPR(n = 15) rib fractures were detected in 93%, sternal fractures in 93%, and no patients were without thoracic fracture. In two patients severe cardiac injuries occurred clearly attributable to CPR. In conclusion cardiopulmonary resuscitation by the ACD-technique caused rib and sternal fractures more often than Std CPR and has a higher risk for iatrogenic cardiac and possible fatal injury.

Cardiopulmonary resuscitation after thoracic surgery: echocardiographic observations

We report echocardiographic observations during external chest compression in a patient with marked abnormalities in thoracic anatomy following emergency surgery of aortic arch aneurysm. Transesophageal echocardiography demonstrated direct right ventricular, aortic and left atrial compression, only minimal left ventricular compression and an open mitral valve during closed chest heart massage. Colour flow doppler demonstrated forward blood flow across the mitral valve and along the left ventricular outflow tract during the compression phase. Echocardiographic findings indicate that factors apart from simple cardiac pump mechanism contributed to blood flow during cardiopulmonary resuscitation (CPR) in this postoperative patient after a major thoracic surgical intervention.

[The results of prehospital cardiopulmonary resuscitation in the initial years of a mobile emergency care system]

In this study the outcome of out-of-hospital cardiac arrest (CA) was analyzed during the first 3 years after installation of a mobile intensive care unit (MICU). The unit is staffed by an anesthesiologist as the emergency-care physician and specially trained health-care personnel. The success of cardiopulmonary resuscitation (CPR) was classified into three stages: (1) CPR with temporary cardiac output; (2) CPR primarily successful with spontaneous rhythm and a palpable pulse; (3) CPR, definitely successful resulting in the patient's discharge from the hospital without important neurological sequelae. All patients are grouped according to the disease underlying the CA. The performance of bystander CPR was recorded. The influence the factors sex, age, response time, cardiac rhythm, location of the collapse and period of investigation (1st year, 2nd year, 3rd year) had on the outcome was analyzed. RESULTS. Eighty-nine patients (32.96%) had a temporary cardiac output; 56 patients (20.74%) were primarily successfully resuscitated; and 12 patients (4.44%) survived without important neurological sequelae. Most of the diseases underlying the CA were in the internal disease group. Only 16 cases of bystander CPR performance were recorded. In the group with primarily successful CPR, significantly important factors arose with the increasing CPR success rate due to the period of investigation (1st year: 10.00%, 2nd year: 19.61%, 3rd year: 30.77%) and due to cardiac rhythm "ventricular fibrillation" (34.62%) and "asystole" (11.88%). Furthermore, significantly important factors were found for definite CPR success when comparing males (1.72%) and females (10.64%) and comparing the location of the collapse "in public places" (9.80%) and "at home" (2.00%). CONCLUSION. Our study shows that in spite of installing a MICU, the outcome of CPR is poor without supplementary measures. We consider that systematically teaching the public about basic life support measures and teaching medical students about emergency medicine will lead to a better CPR success rate in combination with continuing education of the MICU personnel.