Development and evaluation of a point-of-care ultrasound curriculum for paramedics in Germany - a prospective observational study and comparison.

BACKGROUND: Point-of-care ultrasound (POCUS) is steadily growing in use in prehospital emergency medicine. While currently used primarily by emergency physicians, POCUS could also be employed by paramedics to support diagnosis and decision-making. Yet to date, no paramedicine-targeted POCUS curricula exist in Germany. Furthermore, given time and resource constraints in paramedic training, it is unclear whether paramedics could feasibly learn POCUS for prehospital deployment. Hence, this study outlines the development and implementation of a comprehensive POCUS curriculum for paramedics. Through this curriculum, we investigate whether paramedics can attain proficiency in POCUS comparable to other user groups. METHODS: In this prospective observational study, we first developed a blended learning-based POCUS curriculum specifically for paramedics, focusing on basic principles, the RUSH-Protocol and ultrasound guided procedures. Participants underwent digital tests to measure their theoretical competence before (T1) and after the digital preparation phase (T2), as well as at the end of the on-site phase (T3). At time point T3, we additionally measured practical competence using healthy subjects and simulators. We compared the theoretical competence and the practical competence on a simulator with those of physicians and medical students who had also completed ultrasound training. Furthermore, we carried out self-assessment evaluations, as well as evaluations of motivation and curriculum satisfaction. RESULTS: The paramedic study group comprised n = 72 participants. In the theoretical test, the group showed significant improvement between T1 and T2 (p < 0.001) and between T2 and T3 (p < 0.001). In the practical test on healthy subjects at T3, the group achieved high results (87.0% ± 5.6). In the practical test on a simulator at T3, paramedics (83.8% ± 6.6) achieved a lower result than physicians (p < 0.001), but a comparable result to medical students (p = 0.18). The results of the study group's theoretical tests (82.9% ± 9.2) at time point T3 were comparable to that of physicians (p = 0.18) and better than that of medical students (p < 0.01). The motivation and attitude of paramedics towards the prehospital use of POCUS as well as their self-assessment significantly improved from T1 to T3 (p < 0.001). The overall assessment of the curriculum was positive (92.1 ± 8.5). CONCLUSION: With our tailored curriculum, German paramedics were able to develop skills in POCUS comparable to those of other POCUS learners. Integration of POCUS into paramedics' training curricula offers opportunities and should be further studied.

Spreading convulsions, spreading depolarization and epileptogenesis in human cerebral cortex.

Spreading depolarization of cells in cerebral grey matter is characterized by massive ion translocation, neuronal swelling and large changes in direct current-coupled voltage recording. The near-complete sustained depolarization above the inactivation threshold for action potential generating channels initiates spreading depression of brain activity. In contrast, epileptic seizures show modest ion translocation and sustained depolarization below the inactivation threshold for action potential generating channels. Such modest sustained depolarization allows synchronous, highly frequent neuronal firing; ictal epileptic field potentials being its electrocorticographic and epileptic seizure its clinical correlate. Nevertheless, Leão in 1944 and Van Harreveld and Stamm in 1953 described in animals that silencing of brain activity induced by spreading depolarization changed during minimal electrical stimulations. Eventually, epileptic field potentials were recorded during the period that had originally seen spreading depression of activity. Such spreading convulsions are characterized by epileptic field potentials on the final shoulder of the large slow potential change of spreading depolarization. We here report on such spreading convulsions in monopolar subdural recordings in 2 of 25 consecutive aneurismal subarachnoid haemorrhage patients in vivo and neocortical slices from 12 patients with intractable temporal lobe epilepsy in vitro. The in vitro results suggest that γ-aminobutyric acid-mediated inhibition protects from spreading convulsions. Moreover, we describe arterial pulse artefacts mimicking epileptic field potentials in three patients with subarachnoid haemorrhage that ride on the slow potential peak. Twenty-one of the 25 subarachnoid haemorrhage patients (84%) had 656 spreading depolarizations in contrast to only three patients (12%) with 55 ictal epileptic events isolated from spreading depolarizations. Spreading depolarization frequency and depression periods per 24 h recording episodes showed an early and a delayed peak on Day 7. Patients surviving subarachnoid haemorrhage with poor outcome at 6 months showed significantly higher total and peak numbers of spreading depolarizations and significantly longer total and peak depression periods during the electrocorticographic monitoring than patients with good outcome. In a semi-structured telephone interview 3 years after the initial haemorrhage, 44% of the subarachnoid haemorrhage survivors had developed late post-haemorrhagic seizures requiring anti-convulsant medication. In those patients, peak spreading depolarization number had been significantly higher [15.1 (11.4-30.8) versus 7.0 (0.8-11.2) events per day, P = 0.045]. In summary, monopolar recordings here provided unequivocal evidence of spreading convulsions in patients. Hence, practically all major pathological cortical network events in animals have now been observed in people. Early spreading depolarizations may indicate a risk for late post-haemorrhagic seizures.

[Lung ultrasound in COVID-19]. / Lungensonographie bei COVID­19.

Providing medical care to patients suffering from the coronavirus disease 2019 (COVID-19) pandemic is a major challenge for government healthcare systems around the world. The new coronavirus called severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), shows a high organ specificity for the lower respiratory tract. Since there is so far no effective treatment or vaccination against the virus, early diagnostic recognition is of great importance. Due to the specific aspects of the infection, which mainly begins in the peripheral lung parenchyma, lung ultrasonography is suitable as a diagnostic imaging method to identify suspected cases as such in the early stages of the disease. Serial ultrasound examinations on patients with confirmed COVID-19 can promptly detect changes in the affected lung tissue at the bedside. This article summarizes the diagnostic potential of lung ultrasound with respect to screening and therapeutic decision-making in patients with suspected or confirmed SARS-CoV­2 pneumonia.

[Emergency ultrasound in patients with abdominal pain - where should we "look"]. / Notfallsonografie - Patient mit Bauchschmerzen.

Diagnostic ultrasound is without doubt the imaging technique of choice in patients with acute abdominal pain. Point-of-care ultrasound examinations can help to reduce the number of possible differential diagnoses by exclusion or - as a best case scenario - show us directly the correct diagnosis. Hence patients can benefit from a very early appropriate therapeutic approach. This article illustrates where and how we should "look". After focusing on basic technical settings, typical pathological sonomorphologic changes in patients with some of the most important illnesses are characterized (e. g. acute appendicitis, acute cholecystitis, acute diverticulitis, acute pancreatitis and urinary tract occlusion). Ultrasound beginners are the target group of this survey.

[Critical care ultrasound of the thorax - what is the procedure?]. / Notfallsonografie des Thorax.

Despite the limitations (especially that ultrasound does not penetrate air containing lung tissue) ultrasound of the thorax is a very suitable method as a complementary or even primary diagnostic tool. Bedside availability and no radiation exposure are real advantages. However we always have to keep in mind that we are blind for deeper lung processes that do not have contact to the visceral pleura.This article illustrates where and how to look for pathologies and what we have to expect in patients. According to symptoms such as dyspnea, dyspnea with fever and thorax pain with and without trauma, the sonographic morphology of important illnesses in emergency situation are described. The use of ultrasound can help to distinguish between differential diagnosis such as acute exacerbation of COPD vs. heart failure, pleuritis vs. pulmonary embolism, rip fracture vs. "simple" bone contusion and blunt chest trauma with or without pneumothorax.

Bioelectrical behaviour of hypoxic human neocortical tissue under the influence of nimodipine and dimethyl sulfoxide.

Nimodipine and dimethyl sulfoxide (DMSO) have been shown to affect electrophysiological responses in rodent brain tissue in an vitro model of hypoxia. In the present study, the same agents were now examined for their effects on human neocortical brain slices under repeated hypoxic conditions. DMSO (0.4%), with and without addition of nimodipine (40 micromol/l), did not increase the latency of anoxic depolarization (AD). This finding is not in line with our previous observations of DMSO effects, with and without nimodipine, on brain slices of guinea pigs. AD latency was significantly longer in human neocortical brain slices compared with hippocampal slices of rodents even without any pharmacological influence. A possible acute effect of DMSO-nimodipine may therefore be masked by an interspecies difference of hypoxia resistance.

Liver perfusion with dynamic multidetector-row computed tomography as an objective method to evaluate the efficacy of chemotherapy in patients with colorectal cancer.

A total of 24 liver metastases of colorectal cancer were evaluated by dynamic multiphasic CT. Under chemotherapy, follow-up examinations were performed every 3 months. The tumor marker CEA before vs. after chemotherapy correlated with the mean contrast enhancement within the margin of metastases. The total size of metastases correlated with the size of central necrosis as well as with the size of marginal contrast enhancement. CT is able to quantify perfusion and local activity of liver metastases to determine the efficacy of chemotherapy.

Neocortical microenvironment in patients with intractable epilepsy: potassium and chloride concentrations.

PURPOSE: The regulation of extracellular ion concentrations plays an important role in neuronal function and epileptogenesis. Despite the many studies into the mechanisms of epileptogenesis in human experimental models, no data are available regarding the fluctuations of extracellular potassium ([K(+)](o)) and chloride ([Cl(-)](o)) concentrations, which could underlie seizure susceptibility in human chronically epileptic tissues in vivo. METHODS: By using cerebral microdialysis during surgical resection of epileptic foci, the basic [K(+)](o) and [Cl(-)](o) as well as their changes after epicortical electric stimulation were studied in samples of dialysates obtained from 11 patients by ion-selective microelectrodes. RESULTS: The mean basal values of [K(+)](o) and [Cl(-)](o) in all patients were 3.83 +/- 0.08 mM and 122.9 +/- 2.6 mM, respectively. However, significant differences were observed in the basal levels of both [K(+)](o) and [Cl(-)](o) between different patients. Statistically, no correlation was found between basal [K(+)](o) or [Cl(-)](o) and electrocorticogram (ECoG) spike activity, but in one patient, dramatically lowered baseline [Cl(-)](o) was accompanied by enhanced ECoG spike activity. Application of epicortical electrical stimulation increased [K(+)](o) but not [Cl(-)](o) in all cases. According to the velocity as well as spatial distribution of [K(+)](o) reduction to the prestimulation levels, three different types of responses were observed: slow decline, fast decline, and slow and fast declines at adjacent sites. CONCLUSIONS: These data may represent abnormalities in ion homeostasis of the epileptic brain.

Comparison of brain extracellular fluid, brain tissue, cerebrospinal fluid, and serum concentrations of antiepileptic drugs measured intraoperatively in patients with intractable epilepsy.

PURPOSE: The mechanisms of drug resistance in epilepsy are only incompletely understood. According to a current concept, overexpression of drug efflux transporters at the blood-brain barrier may reduce levels of antiepileptic drugs (AEDs) in epileptogenic brain tissue. Increased expression of drug efflux transporters such as P-glycoprotein has been found in brain tissue surgically resected from patients with medically intractable epilepsy, but it is not known whether this leads to decreased extracellular (interstitial) AED concentrations in affected brain regions. This prompted us to measure concentrations of AEDs in the extracellular space of human neocortical tissue by using intraoperative microdialysis (IOMD) in those parts of the brain that had to be removed for therapeutic reasons. For comparison, AED levels were determined in brain tissue, subarachnoid CSF, and serum. METHODS: Concentrations of carbamazepine (CBZ), 10-hydroxy-carbazepine (10-OH-CZ, metabolite of oxcarbazepine), lamotrigine (LTG), levetiracetam (LEV), topiramate, or phenytoin were determined by using one to four catheters during IOMD in the medial temporal gyrus. Furthermore, to calculate the individual recovery of every catheter, an in vitro microdialysis was performed with ultrafiltrate of serum concurrently obtained from the respective patient. In addition, AED levels were determined in the resected brain tissue, CSF, and serum of the same patients. Altogether 22 pharmacoresistant epilepsy patients (nine male, 13 female patients; age 15-54 years) with complex partial seizures or secondarily generalized seizures were involved. In a first series, IOMD samples 40 min after beginning of the microdialysis (flow rate, 1 microl/min), and in a second series, continuous measurements 25, 30, 35, and 40 min from the beginning were evaluated (flow rate, 2 microl/min). With in vitro recovery data of the individual catheters, the concentration in the extracellular space (ECS) was estimated. RESULTS: AED concentrations in the ECS of the cortex measured by catheters located at a distance of 0.6 cm differed markedly in some patients, whereas concentrations in the ultrafiltrate of the serum of the respective patients measured with the same catheters varied only slightly. Furthermore, ECS concentrations related to the ultrafiltrate of serum showed considerable interindividual variations. The high intra- and interindividual variation of ECS concentrations is demonstrated by the low correlation between concentrations in ECS and the ultrafiltrate of serum (CBZ, r= 0.41; 10-OH-CZ, r= 0.42; LTG, r= 0.27) in contrast to the high correlation between brain tissue concentration and the ultrafiltrate of serum (CBZ, r= 0.97; 10-OH-CZ, r= 0.88; LTG, r= 0.98) in the same group of patients. When comparing AED concentrations in the ECS with those in the CSF, ECS concentrations were significantly lower for CBZ, 10-OH-CZ, LTG, and LEV. CONCLUSIONS: The data demonstrate that AED concentrations show a considerable intraindividual and interindividual variation in the ECS of cortical regions. Furthermore, the ECS concentration of several AEDs is significantly lower than their CSF concentration in patients with intractable epilepsy. However, in the absence of data from nonepileptic tissues, it is not possible to judge whether the present findings relate to overexpression of multidrug transporters in the brain. Instead, the present study illustrates the methodologic difficulties involved in performing IOMD studies in patients and may thus be helpful for future approaches aimed at elucidating the role of multidrug transporters in epilepsy.

Intrinsic excitability, synaptic potentials, and short-term plasticity in human epileptic neocortex.

Although studies of epileptic human hippocampus suggest changes of synaptic and intrinsic excitability, few changes, save the appearance of spontaneous field/synaptic potentials, are known in epileptic neocortical tissue. However, invasive EEG and histological studies suggest that neocortical tissue, even in mesial temporal lobe epilepsy, can play an important role as an irritative zone or extrahippocampal focus. We hypothesized that intrinsic neuronal and synaptic excitability, as well as short-term plasticity, are altered in neocortical areas, particularly with elevated K+ levels as occur during seizures. We analyzed neuronal firing properties, synaptic responses, and paired-pulse plasticity in human neocortical slices from tissue resected during epilepsy surgery, both under normal and under pathological conditions, i.e., after elevating K+ (4/8 mM), with rat neocortical slices as controls. Neuronal firing properties were not different. We did find, however, alterations of synaptic responsiveness in epileptic tissue, i.e., an elevated network excitability with K+ elevations, and reduction of paired-pulse depression.