[Prehospital management of acute stroke : Using the example of Saarland ambulance services]. / Prähospitalphase der Schlaganfallversorgung : Am Beispiel des saarländischen Rettungsdienstes.

BACKGROUND: The preclinical care strategy was changed after reevaluation of endovascular thrombectomy in the S2k guideline of the German Neurological Society (DGN). Severe strokes should be directly transferred to neurovascular centers (model "mothership"). The severity of a stroke should be determined using the LAMS (Los Angeles Motor Scale) score. MATERIALS AND METHODS: The general conditions of preclinical care of patients with stroke in the Saarland are presented. The key figures and statistical data of clinic assignments in the adapted care strategy are evaluated. RESULTS: The 2018 data from the Saarland Ambulance Services indicate that 9.1% of all preclinical emergencies are diagnosed with "transient ischemic attack (TIA)/insult/bleeding"; 97.1% of these patients were admitted to one of the 10 hospitals in Saarland with a stroke unit. A care time at the emergency site of 20 min was observed in 78.2%, a prehospital time of 60 min in 90.1% of the missions. Preclinically, severe strokes with LAMS score ≥4 were detected in 19.2% of all stroke patients; 71.6% of these severe strokes were assigned to one of two neurovascular centers in the Saarland. CONCLUSIONS: With good traffic and hospital infrastructure in Saarland, severe strokes can be treated primarily in neurovascular centers. Differentiated care requirements with monitoring of key figures in medical quality management and clear agreements with the target hospitals in the implementation of a common care strategy are essential.

[Significance of Helicopter Emergency Medical Service in Prehospital Trauma Care]. / Bedeutung der Luftrettung bei der präklinischen Traumaversorgung.

BACKGROUND: In the late 1960s, the helicopter emergency medical service (HEMS) was established in Germany because of an increasing number of severe injuries in traffic accidents. To get a doctor quickly on scene was the initial intention, rather than transporting the patient. Today, rescue helicopters cover the entire field of emergency medicine and are an important transportation device for polytrauma patients. MATERIAL AND METHODS: The importance of the HEMS for the treatment of severely injured patients was examined by an analysis of the databases of the leading air rescue organisations ADAC and DRF Luftrettung (2005-2011). RESULTS: Traumatological cases, albeit with large regional differences, make up 35 % of all uses of the helicopter emergency services. CONCLUSIONS: For the multiply injured patient in particular, in over 40 % of the cases there is a joint patient care involving both helicopter- and ambulance-based emergency services. The HEMS undertakes especially the rapid, if necessary, even transregional transport to specialised trauma centres.

[Improvement of emergency physician education through simulator training. Consideration on the basis of the model project "NASimSaar25"]. / Verbesserung der Notarztausbildung durch Simulatortraining. Betrachtung anhand des Modellprojekts "NASimSaar25"

BACKGROUND: Prehospital emergency medicine is a challenge for trainee emergency physicians. Rare injuries and diseases as well as patients in extreme age groups can unexpectedly face emergency physicians. In the regulations on medical education the German Medical Association requires participation in 50 emergency missions under the supervision of an experienced emergency physician. This needs to be improved because on-the-job training does not generally represent the whole spectrum of emergency medicine and a good and structured training under on call conditions is nearly impossible. AIM: The subject of the model project described was whether practical training for emergency physicians can be achieved by participation in simulation training instead of real emergency situations. MATERIAL AND METHODS: After modification of the Saarland regulations on medical education it was possible to replace up to 25 participations in emergency missions by simulation training. The concept of the course NASimSaar25 requires participants to complete 25 simulator cases in 3 days in small training groups. Emergency situations from all medical disciplines need to be treated. A special focus is on the treatment of life-threatening and rare diseases and injuries. Modern simulators and actors are used. The debriefings are conducted by experienced tutors based on approved principles. Medical contents, learning targets from the field of crew resource management (CRM) and soft skills are discussed in these debriefings. RESULTS: Education in the field of emergency medicine can be improved by simulator-based learning and training. However, practical work under a tutor in real and clinical experience cannot be completely replaced by simulation. Simulator training can only be successful if theoretical knowledge has already been acquired. CONCLUSION: A simulator-based course concept can result in an improvement of emergency medical education. The model project NASimSaar25 was well received by the target audience and mostly very well evaluated in terms of learning and reality. If this project becomes established the demand on simulation-based training will increase. The training should achieve a consistent standard of quality.

[Intraosseous infusion in the German Air Rescue Service : Guideline recommendations versus mission reality]. / Intraossäre Punktion im deutschen Luftrettungsdienst : Leitlinienempfehlungen vs. Einsatzrealität.

BACKGROUND: In emergency medicine intraosseous access (IOA) has been established as an alternative to conventional intravenous access. Originally the use of IOA was strictly limited to children up to 6 years of age and to adults for cardiopulmonary resuscitation. These limitations have been relaxed and the indications for IOA have been expanded. MATERIAL AND METHODS: A retrospective nationwide analysis of rescue missions by all helicopter emergency medical services of the German Automobile Club (ADAC) Air Rescue Service as well as the German Air Rescue (DRF) over a 7-year period was carried out. RESULTS: A total of 466,813 patients were treated during the study period and an IOA was established in 1,498 (0.32 %) patients. There was a significant increase in using an IOA from 0.1-0.5 % (p < 0.05) from 2005 to 2011. Furthermore, there was an increase in using an IOA in elderly patients and in patients with lower degrees of severity according to the National Advisory Committee for Aeronautics (NACA) scales (2005-2011): decreased use of IOA in patients up to 6 years of age from 92.4 % to 19.7 % (p < 0.05) and in patients with NACA grades VII/VI from 74.4 % to 46.6 % (p < 0.05) and temporarily limited increase of non-indicated IOA use in patients with NACA grade III between 2008 and 2010. Furthermore, there was an increase in the number of the different drug groups used for intraosseous infusion over the study period. CONCLUSION: The current guidelines and recommendations for the use of IOA in the prehospital setting are reflected more and more in mission reality for helicopter emergency medical services.

Mobile stroke unit for diagnosis-based triage of persons with suspected stroke.

BACKGROUND: In this feasibility study, we tested whether prehospital diagnostic stroke workup enables rational decision-making regarding treatment and the target hospital in persons with suspected stroke. METHODS: A mobile stroke unit that delivers imaging (including multimodal brain imaging with CT angiography and CT perfusion), point-of-care-laboratory analysis, and neurologic expertise directly at the emergency site was analyzed for its use in prehospital diagnosis-based triage of suspected stroke patients. RESULTS: We present 4 complementary cases with suspected stroke who underwent prehospital diagnostic workup that enabled direct diagnosis-based treatment decisions and reliable triage regarding the most appropriate medical facility for that individual, e.g., a primary hospital vs specialized centers of a tertiary hospital. CONCLUSIONS: This preliminary report demonstrates the feasibility of prehospital diagnostic stroke workup for immediate etiology-specific decision-making regarding the necessary time-sensitive stroke treatment and the most appropriate target hospital.

[Extended medical quality management exemplified by the tracer diagnosis multiple trauma. Pilot study in the air rescue service]. / Erweitertes medizinisches Qualitätsmanagement am Beispiel der "Tracer"-Diagnose "Polytrauma". Pilotstudie aus dem Bereich des Luftrettungsdienstes.

BACKGROUND: Adequate prehospital and inhospital primary care is a decisive factor in the successful treatment of multiple trauma patients. For optimization of treatment algorithms the implementation of a medical quality management is of utmost importance. The aim of this study was to extend quality management by including data on process quality. METHODS: A retrospective study of primary rescue missions of the Helicopter Emergency Medical Service (HEMS) Christoph 22 in Ulm over a period of 2.5 years was performed. In a detailed analysis of filter criteria, in which relevant deviations from the recommendations (not fulfilled in > 10% of the cases) occurred, process data was included (vital data, measurements and events). RESULTS: In the study population (n = 298, males 71.8%, mean age 39.8 ± 21.8 years) 2 filter criteria were identified in which relevant deviations where observed: time management where prehospital treatment time ≤ 60 min in 36% of the cases was not fulfilled and circulatory management where the systolic blood pressure, detected with Riva-Rocci method (RR(sys)) ≥ 120 mmHg on hospital admission in patients with severe head trauma was not fulfilled in 45% of the cases. In patients with deviations in time management, prehospital treatment time was prolonged (75.6 ± 18.3 min versus 50.5 ± 6.7 min; p < 0.01) caused by a prolonged on scene attendance time (34.1 ± 22.1 min versus 20.6 ± 9.2 min; p < 0.01) and transport time (17.3 ± 9.4 min versus 13.3 ± 4.8 min; p < 0.01). In entrapment trauma prehospital treatment time was expanded (44% versus 10%; p < 0.01). Patients in whom circulatory management deviations were observed were more often in shock on arrival at the scene (RR(sys) ≤ 90 mmHg: 60% versus 30%; p < 0.01), more often hypoxemic [pulse oximeter oxygen saturation (S(p)O(2)) ≤ 90%: 36% versus 19%; p < 0.05] and more often sustained a trauma to the chest as well as to chest and abdomen/pelvis (69% versus 52% and 42% versus 28%, respectively; p < 0.05). Furthermore, the infusion volume of colloids was higher (1241 ± 810 ml versus 753 ± 359 ml; p < 0.05) and the combined usage of small volume resuscitation and catecholamines was more often necessary (42% versus 25%; p < 0.05). CONCLUSIONS: Including process data of prehospital mission data recording facilitates an extended medical quality management.

[Use of intraosseus infusion in the German air rescue service : nationwide analysis in the time period 2005 to 2009]. / Einsatz der intraossären Infusion im deutschen Luftrettungsdienst : Bundesweite Analyse im Zeitraum von 2005 bis 2009.

BACKGROUND: Intraosseous infusion has become established as a fast and safe alternative to conventional vascular access in emergency situations. Originally the use of intraosseous access was limited to children up to 6 years of age and to adults for cardiopulmonary resuscitation but this limitation has now been removed. The aim of this study was to obtain data on mission reality regarding the use of intraosseous access in the prehospital setting against the background of the expanded recommendations on the use of the intraosseous infusion. METHODS: An analysis of rescue missions by all rescue helicopters of the ADAC (German Automobile Club) Air Rescue as well as the German Air Rescue Service (58 helicopter emergency medical service bases) over a 4 year period from January 2005 to December 2008 was carried out. RESULTS: A total of 247,454 rescue missions were carried out during the study period and in 525 patients (0.2% of the total study collective) an intraosseous access was established. There was a significant increase in the intraosseous infusion rate from 0.1% to 0.4% (p<0.05). Furthermore, there was a significant increase in its use in elderly patients and in patients with lower National Advisory Committee for Aeronautics (NACA) scores (2005 vs. 2008): 92.4% vs. 42.9% of all intraosseous infusions in patients ≤ 6 years of age (p<0.05) and 74.4% vs. 42.9% of all intraosseous infusions in patients with NACA score VI/VII (p<0.05). The proportion of trauma patients in the total study collective was 33% and there was no significant change in the frequency of trauma cases over the study period but there was a remarkable increase of intraosseous infusions in trauma patients in the last year of the study period compared to the previous years (38% in 2008 vs. 27-30% in 2005-2007). Furthermore, there was an increase in the number of different drug groups used for intraosseous infusion over the study period. CONCLUSIONS: The expanded indication recommendations for the use of intraosseous infusion in the prehospital setting enter more and more mission reality in air rescue services in Germany.

[Primary documentation quality for paper-assisted digital mission data documentation. Initial results from the air rescue service]. / Primäre Dokumentationsqualität bei papiergestützter digitaler Einsatzdokumentation. Erste Ergebnisse aus dem Luftrettungsdienst.

BACKGROUND: With the assistance of digital pen and paper technology in the field of prehospital data reporting, it seems to be possible to fulfill the requirements of "documentation" as well as the requirements of "quality management". The aim of this study was to determine the "primary documentation quality" (PDQ) of a data reporting system based on digital pen and paper technology (so-called DINO) within a helicopter emergency medical service (HEMS) over a 6-month period. RESULTS: The PDQ is defined as the proportion of prehospital documented data, which is primarily recorded correctly by the data reporting system. For the national uniform core dataset (so-called MIND2) the PDQ was 96.7%, for "checkbox" and "numeric data fields" the PDQ was 99.8% and 93.6%, respectively and for "vital data" the PDQ was 96.7% [heart rate (HF), measurement of blood pressure] and 84.1% [peripheral oxygen saturation (S(p)O2), end tidal carbon dioxide concentration (etCO2), oxygen administration (O2)]. For "measurements" the PDQ was 96.9% (time stamps) and 86.9% (time frames), for "drugs" the PDQ was 43.6% (drug name) and 69.8% (drug dosage) and for"placement of infusion" 42% (infusion name) and 85.3% (infusion time), respectively. The average time for the "verification process" after mission completion was 1.5+/-0.4 min/mission. CONCLUSIONS: The "primary documentation quality" of prehospital mission data reporting with the assistance of a digital pen and paper based documentation system (DINO) has been shown to completely fulfill the requirements of rapid and safe data documentation in actual missions, even at this early stage of development.

[Is there an association between the rating of illness and injury severity and the experience of emergency medical physicians?]. / Besteht ein Zusammenhang zwischen der Einschätzung der Vitalgefährdung und der notfallmedizinischen Erfahrung des Notarztes?

BACKGROUND: The illness and injury severity of patients in emergency situations is normally rated by the National Advisory Committee for Aeronautics (NACA) score. Different issues seem to limit the validity of the NACA score, therefore, the aim of the present investigation was to analyse the association between rescue experience of pre-hospital emergency physicians and the estimated jeopardy of patients' vital functions using the NACA score. MATERIAL AND METHODS: In this retrospective study, the emergency chart protocols of patients in a ground-based emergency system from 2004 to 2005 were evaluated concerning patients demographic, diagnosis, and related NACA score. Emergency physicians were divided into two groups according to their experience as pre-hospital emergency physicians (group 1: less than 3 years and group 2: 3 or more years). RESULTS: The patients in groups 1 and 2 were comparable concerning the mean age (58+/-24 years vs. 58+/-24 years) and the percentage of males (each 54%). The reasons for the emergency call in both groups were comparable with respect to disease, trauma, and the combination of both (both 77%, 18%, and 5%, resp.). A higher percentage of emergency physicians of group 1 estimated a lower illness and injury severity score in comparison to emergency physicians of group 2 with a longer working experience (NACA I-III: 56% vs. 48%; p<0.05). Accordingly, physicians in group 1 estimated a smaller percentage of patients to be in life-threatening situations (NACA IV-V: 33% vs. 40%; p<0.05). There were no significant differences in the NACA categories VI (2%) and VII (7%) between both groups. CONCLUSION: The results demonstrate that emergency physicians with less rescue experience rated the severity of illness or injury relatively lower in comparison to colleagues who had worked in the pre-hospital setting for many years.

[Paper-assisted digital Mission documentation in air rescue services. Quality management in preclinical emergency medicine]. / Papiergestützte digitale Einsatzdokumentation im Luftrettungsdienst. Qualitätsmanagement in der präklinischen Notfallmedizin.

BACKGROUND: Recording of adequate mission data is of utmost importance in prehospital emergency medicine. For this, a nationwide uniform core dataset for prehospital data reporting, the so-called MIND 2, was introduced. With this procedure adequate information about structure and outcome quality, but only little information about process quality, can be obtained. Regarding the quality of data recording, primarily computer-based techniques are superior to other techniques. Against this background, the aim of this study was to develop a documentation system, which sets new standards regarding documentation dataset and documentation quality. RESULTS: A primarily computer-based documentation system based on the "digital paper" technology was achieved. This technology allows conventional data entry via a (digital) pen and documentation on conventional paper. As the core-dataset MIND 2 was realized - furthermore, the measurements performed during prehospital management as well as data on vital signs (blood pressure, heart frequency, S(a)O(2), p(et)CO(2) etc.) were included into routine data recording. Integration of this documentation system into an already existing medical quality management system was achieved via a defined interface. Testing of this new system over a 3-month period at the helicopter emergency medical service (HEMS) "Christoph 22" showed a high degree of functionality and stability of the system. Serious problems, especially a total break-down of the whole system, were not observed during the study period. CONCLUSIONS: The new data recording concept, which is based on the "digital paper" technology, has proven to be completely satisfactory with respect to functionality and documentation quality during the test period.

[Prognostic value of routine parameters and laboratory parameters after major trauma. A prospective preclinical-clinical study of air rescue patients]. / Prognostischer Wert von Routineparametern und -laborparametern nach schwerem Trauma. Eine prospektive präklinische-klinische Studie mit Patienten des RTH Christoph 1.

In this prospective study, 273 air rescue patients with major blunt trauma were followed throughout their prehospital and clinical management. A blood sample was taken upon arrival and data acquired at three defined time points. With these data, for the first time a prognosis prediction model with prehospital and early clinical routine parameters and routine lab parameters was tested for predictive power. Coagulation test, value of base excess, Glasgow Coma Scale (GCS) value, severity of injury, and age appeared to be relevant parameters. The probability of survival after major blunt trauma decreases with increasing age and severity of injury and decreasing values in GCS, base excess, and coagulation test. These data showed that it is possible with the help of easily accessible routine parameters and routine lab parameters to predict individual survival with a high degree of accuracy of 82%.

[Vasopressin for therapy of persistent traumatic hemorrhagic shock: The VITRIS.at study]. / Vasopressin zur Therapie eines therapierefraktären traumatisch-hämorrhagischen Schocks: Die VITRIS.at-Studie.

While fluid management is established in controlled hemorrhagic shock, its use in uncontrolled hemorrhagic shock is being controversially discussed, because it may worsen bleeding. In the irreversible phase of hemorrhagic shock that was unresponsive to volume replacement, airway management and catecholamines, vasopressin was beneficial due to an increase in arterial blood pressure, shift of blood away from a subdiaphragmatic bleeding site towards the heart and brain and decrease of fluid resuscitation requirements. The purpose of this multicenter, randomized, controlled, international trial is to assess the effects of vasopressin (10 IU IV) vs. saline placebo IV (up to 3 injections at least 5 min apart) in patients with prehospital traumatic hemorrhagic shock that persists despite standard shock treatment. The study will be carried out by helicopter emergency medical service teams in Austria, Germany, Czech Republic, Portugal, the Netherlands and Switzerland. Inclusion criteria are adult trauma patients with presumed traumatic hemorrhagic shock (systolic arterial blood pressure <90 mmHg) that does not respond to the first 10 min of standard shock treatment (endotracheal intubation, fluid resuscitation and use of vasopressors) after arrival of the first emergency physician at the scene. The time window for randomization will close after 30 min of shock treatment. Exclusion criteria are terminal illness, no intravenous access, age <18 years, injury >60 min before randomization, cardiac arrest before randomization, presence of a do-not-resuscitate order, untreated tension pneumothorax, untreated cardiac tamponade, or known pregnancy. Primary study end-point is the hospital admission rate, secondary end-points are hemodynamic variables, fluid resuscitation requirements and hospital discharge rate.

Realistic assessment of the physician-staffed emergency services in Germany.

In Germany the emergency medical services, which include dispatching emergency physicians to the scene, are considered to be among the best in the world. However, the hospitals admitting these patients still report shortcomings in prehospital care. The quality of an emergency medical service depends on both formal qualification and experience in managing such emergencies. Therefore, we determined how frequently emergency medical service physicians in Germany actually encountered complex and demanding emergency situations outside the hospital and how often they had to carry out emergency interventions. We therefore evaluated data from more than 82,000 ground emergency medical service scene calls registered in the MIND ("minimaler Notarztdatensatz") data base of the state of Baden-Wuerttemberg, Germany and more than 47,000 helicopter emergency medical service scene calls from the "Luftrettungs-, Informations- und Kommunikationssystem" (LIKS) data base of the German ADAC air rescue service. The results, which were unexpectedly distinct, impressively demonstrate that in part emergency medical service staff only encountered some emergencies very rarely. In particular, patients with life-threatening conditions such as acute coronary syndrome, stroke, head trauma, as well as multiple trauma were only treated once every 0.4-14.5 months and cardiopulmonary resuscitation and intubation were only carried out once every 0.5-1.5 months. Furthermore, a time period of 6 months to more than 6 years may pass before a chest tube has to be placed. There are, of course, considerable differences between ground and helicopter emergency medical services. Particularly in areas where the frequency of such emergency cases is low, the clinical experience required to competently manage a demanding emergency situation cannot be gained or maintained just by working in the emergency medical system. As a result of the general pressure to cut costs and also of changes in hospital politics, however, only highly qualified and experienced emergency medical services may survive in Germany in the long term. In addition to formal qualifications and accompanying practice-related courses, future emergency medical service personnel should be drafted from clinical department staff that are experienced in treating severely ill and severely injured patients.

[Pediatric cases in preclinical emergency medicine: critical aspects in the range of missions covered by ground ambulance and air rescue services]. / Pädiatrische Notfälle in der präklinischen Notfallmedizin: Schwerpunkte des Einsatzspektrums im bodengebundenen Rettungsdienst und in der Luftrettung.

BACKGROUND: The aim of this study was to demonstrate differences in structure and severity of pediatric emergencies treated by aeromedical (air rescue) or ground ambulances services. Conclusions for the training of emergency physicians are discussed. PATIENTS AND METHODS: In a 3-year study period, a total of 9,274 pediatric emergencies covered by the ADAC air rescue service are compared to 4,344 pediatric patients of ground ambulance services in Saarland. RESULTS: In aeromedical services pediatric emergencies are more frequent (12.9% vs. 6.4%), trauma predominates (59.9% vs. 35.6%) and severe injuries or diseases occur more frequently (30.5% vs. 15.0%). In both groups pediatric emergency cases are concentrated into very few diagnostic groups: more than one third of the cases involving pre-school children is due to convulsions. Respiratory diseases and intoxication are the next most frequent causes and are more common in ground ambulance patients. Head trauma is the most common diagnosis in cases of pediatric trauma, followed by musculoskeletal and thoracoabdominal trauma. All types of severe trauma are more frequent in pediatric patients of the aeromedical services. CONCLUSIONS: Training of emergency physicians should include pediatric life support and specific information about frequent pediatric emergency situations. For emergency physicians in aeromedical services, an intensive training in pediatric trauma life support is also necessary.

[Preclinical care of trauma patients in air rescue. Results of the medical quality management for patients with severe head injury and polytrauma in the years 2000 and 2001]. / Präklinische Versorgung von Traumapatienten in der Luftrettung Ergebnisse des medizinischen Qualitätsmanagements bei Patienten mit schwerem Schädel-Hirn-Trauma und Polytrauma der Jahre 2000 und 2001.

In a retrospective study of mission data of ADAC Air Rescue of the years 2000 and 2001 the quality of preclinical care of 1,946 patients with severe head injuries and 1,878 polytraumatized patients was examined. The actual preclinical care of these patients was compared with a catalogue of eleven thesis-like recommendations. These recommendations were previously derived from corresponding publications of national and international specialist companies and were introduced in a binding manner by the senior doctors of the participating air rescue centres. The results of the study show that 73.3% of the severe head injuries were preclinically intubated and 94.4% were supplied with oxygen, 82.2% were analgosedated. 94.8% could be delivered to the hospital of destination. 65.9% had a systolic blood pressure of >120 mmHg upon admission to the hospital. 71.4% of severe head injury victims were equipped with a cervical support, 23.3% had the blood pressure documented. 47.3% reached the hospital of destination in less than 60 minutes. Among polytraumatic patients the intubation was performed in 75.7%, the supply with oxygen in 90.7%, 88.6% of the patients were analgosedated. 78.7% of patients suffering from concomitant head injuries were provided with a cervical support and only 22.8% had a blood sugar measurement documented. A concomitant severe thorax trauma was treated by a thorax drainage in 59.2%. 35.6% of the polytraumata reached the hospital of destination in less than 60 minutes. The work describes the preclinical patient care of severe head injuries and polytraumata, pointing out deficits and presenting optimization possibilities, particularly in the area of training. Furthermore, the work shows the concept of the medical quality management in an air rescue enterprise. The total evaluation of all air rescue centres participating in data collection forms the basis of an external quality comparison. The data evaluation of a single station makes regional strengths and weaknesses visible, deficits can be proven and proposals for optimization be developed. The presentation of the time history of data yields continuous standard information on the state of the patient care at the relevant air rescue location and enables the analysis of improvement concepts based on the updated data.

The measurement of enzyme activities in the resting human polymorphonuclear leukocyte--critical estimate of a method.

As a system for study, the isolated human polymorphonuclear leukocyte combines the advantages of a quasi-non-invasive preparation with a nearly complete complement of enzymes of carbohydrate and energy metabolism. However, small sample volumes and, in some cases, very low enzyme activities make high demands on sample processing, storage, and performance of continuous measurements, if the enzyme activities are to be measured with acceptable reproducibility. In the presented study several aspects of homogenization, storage, and continuous measurement were scrutinized, to identify critical steps and consider ways of optimizing the method. Polymorphonuclear leukocytes were separated from the blood of healthy subjects by sedimentation and density gradient centrifugation. After ultrasonic homogenization, 13 enzymes of glycolysis and gluconeogenesis, the tricarboxylic acid cycle, and glycogen metabolism were determined photometrically. The variation of several conditions showed: 1. The duration of exposure to ultrasound for the homogenization of polymorphonuclear leukocytes has no influence over a wide range of time. 2. Addition of the detergents Triton X-100 and deoxycholic acid, as well as the SH-group protector dithiothreitol, to the homogenizing medium increased the measured activities of only a few enzymes. 3. Considerable inaccuracy was encountered when the suspension was divided into parts for homogenization with different additives; such splitting of the suspension should therefore be performed only when necessary, as in the determination of reference values (e.g. protein or DNA content of the cell suspension). 4. Twenty four-fold determination of enzyme activities from one homogenate resulted in precisions between 4.5% (citrate synthase) and 14.4% (transketolase), which is satisfactory for the low activities (as low as 1 U/l) in the homogenate. 5. The reproducibility of enzyme activities, measured in homogenates of polymorphonuclear leukocytes from different blood samples drawn simultaneously, was only slightly worse than that of the continuous measurement method itself. Thus, the precision of the measurement of enzyme activity seems to be the main determinant of the overall method. In conclusion, the described procedure of separation, homogenization, and enzyme measurement in human polymorphonuclear leukocyte meets the requirements of biochemical or clinical trials and can be recommended for clinical metabolic studies.