Zaburzenia funkcji bareceptorów tętniczych po urazach mózgu

Baroreceptory są zakończeniami aferentnych włókien czuciowych zlokalizowanymi w łuku aorty i w zatoce szyjnej. Ich funkcja jest związana z kontrolą ciśnienia tętniczego i ochroną serca przed arytmią poprzez działanie analogiczne do pętli ujemnego sprzężenia zwrotnego między wartością ciśnienia a impulsacją z nerwu błędnego. W wyniku urazów mózgu bardzo często dochodzi do powikłań sercowo-naczyniowych związanych z upośledzeniem odruchu z baroreceptorów tętniczych. W niniejszej pracy przedstawiono przegląd literatury obejmujący chorych z urazowym uszkodzeniem mózgu, a dotyczący związku między rozległością urazu, zmianami w czułości baroreceptorów i odległymi wynikami leczenia. Wyniki dotychczasowych badań wskazują, że zaburzenia odruchu z baroreceptorów mogą prowadzić do wielu powikłań, w tym zwiększenia liczby zgonów — zarówno we wczesnym, jak i odległym czasie od zachorowania. Może to świadczyć o trwałym upośledzeniu współczulno-przywspółczulnej kontroli układu sercowo-naczyniowego. Jedną z ważnych ról baroreceptorów jest ich wpływ na rozwój ostrego niedokrwienia mózgu, między innymi poprzez spowodowanie wzrostu aktywności czynników zapalnych — interleukin w mózgu oraz zmian w centralnej sieci autonomicznej

Baroreflex sensitivity and heart rate variability are predictors of mortality in patients with aneurysmal subarachnoid haemorrhage.

OBJECT: We aimed to investigate the link between the autonomic nervous system (ANS) impairment, assessed using baroreflex sensitivity (BRS) and heart rate variability (HRV) indices, and mortality after aneurysmal subarachnoid haemorrhage (aSAH). METHODS: A total of 57 patients (56 ± 18 years) diagnosed with aSAH were retrospectively enrolled in the study, where 25% of patients died in the hospital. BRS was calculated using a modified cross-correlation method. Time- and frequency-domain HRV indices were calculated from a time-series of systolic peak intervals of arterial blood pressure signals. Additionally, cerebral autoregulation (CA) was assessed using the mean velocity index (Mxa), where Mxa > 0 indicates impaired CA. RESULTS: Both BRS and HRV indices were lower in non-survivors than in survivors. The patients with disturbed BRS and HRV had more extensive haemorrhage in the H-H scale (p = .040) and were more likely to die (p = .013) when compared to patients with the intact ANS. The logistic regression model for mortality included: the APACHE II score (p = .002; OR 0.794) and the normalised high frequency power of the HRV (p < <.001; OR 0.636). A positive relationship was found between the Mxa and BRS (R = 0.48, p = .003), which suggests that increasing BRS is moderately strongly associated with worsening CA. CONCLUSION: Our results indicated that lower values of HRV indices and BRS correlate with mortality and that there is a link between cerebral dysautoregulation and the analysed estimates of the ANS in aSAH patients

Critical Closing Pressure During Controlled Increase in Intracranial Pressure - Comparison of Three Methods

Critical closing pressure (CrCP) is the arterial blood pressure (ABP) threshold, below which small arterial vessels collapse and cerebral blood flow ceases. Here we aim to compare three methods for CrCPestimation in scenario of a controlled increase in intracranial pressure (ICP), induced by infusion tests performed in patients with suspected normal pressure hydrocephalus (NPH). METHODS: Computer recordings of directly-measured ICP, ABP and transcranial Doppler cerebral blood flow velocity (CBFV), from 37 NPH patients undergoing infusion tests, were retrospectively analyzed. The CrCP was calculated with three methods: one with the first harmonics ratio of the pulse waveforms of ABP and CBFV (CrCPA) and two methods based on a model of cerebrovascular impedance, as functions of both cerebral perfusion pressure (CrCPinv), and of ABP (CrCPninv). CONCLUSION: All methods give similar results in response to ICP changes. In the case of individual CrCP measurements for each patient, CrCPA may provide negative, non-physiological values. Invasive critical closing pressure is most sensitive to variations in ICP and CPP and can be used as an indicator of the cerebrospinal and the cerebrovascular system status during infusion tests.This study was partially supported by the statutory fund of the Mossakowski Medical Research Centre Polish Academy of Sciences and Institute of Electronic Systems, Warsaw University of Technology. Katarzyna Kaczmarska was also supported by the European Union in the framework of the European Social Fund through the Warsaw University of Technology Development Programme

Monitorowanie utlenowania mózgu za pomocą spektroskopii w bliskiej podczerwieni u chorych po krwotoku podpajęczynówkowym z pękniętego tętniaka

Metoda spektroskopii w bliskiej podczerwieni (NIRS, near infrared spectroscopy) umożliwia nieinwazyjny pomiar regionalnego utlenowania mózgu (rSO2), dzięki wykorzystaniu selektywnej absorpcji promieniowania fal elektromagnetycznych z zakresu 660–940 nm, przez obecne w organizmie człowieka chromofory. W praktyce klinicznej NIRS jest używana jako narzędzie wspomagające monitorowanie stanu pacjenta, między innymi w czasie operacji. Doniesienia literaturowe wskazują na przydatność tej metody w diagnostyce wczesnych zmian niedokrwiennych oraz zaburzeń w perfuzji mózgu. W pracy przedstawiono zasadę działania NIRS oraz zaprezentowano możliwości wykorzystania tej metody w diagnostyce zaburzeń w ośrodkowym układzie nerwowym. Dokonano także przeglądu prac naukowych, przedstawiających zastosowanie NIRS do monitorowania chorych po krwotoku podpajęczynówkowym z pękniętego tętniaka. Mimo ograniczeń technicznych, dane z piśmiennictwa wskazują na duże możliwości wykorzystania NIRS w diagnostyce zaburzeń krążenia mózgowego, co ułatwi ocenę stanu pacjenta oraz pozwoli na prognozowanie wczesnych i odległych wyników leczenia

A comparison of the time constant of the cerebral arterial bed using invasive and non-invasive arterial blood pressure measurements

Abstract: Objective: The time constant of the cerebral arterial bed (τ), which is an index of brain haemodynamics, can be estimated in patients using continuous monitoring of arterial blood pressure (ABP), transcranial Doppler cerebral blood flow velocity (CBFV) and intracranial pressure (ICP) if these measures are available. But, in some clinical scenarios invasive measurement of ABP is not feasible. Therefore, in this study we aimed to investigate whether invasive ABP can be replaced with non-invasive ABP, monitored using the Finapres photoplethysmograph (fABP). Approach: Forty-six recordings of ICP, ABP, fABP, and CBFV in the right and left middle cerebral arteries were performed daily for approximately 30 min in 10 head injury patients. Two modelling approaches (constant flow forward [CFF, pulsatile blood inflow and steady blood outflow] and pulsatile flow forward [PFF, where both blood inflow and outflow are pulsatile]) were applied to estimate τ using either invasive ABP (τCFF, τPFF) or non-invasive ABP (fτCFF, fτPFF). Main results: Bland–Altman analysis showed quite poor agreement between the fτ and τ methods of estimation. The fτ method produced significantly higher values than the τ method when calculated using both the CFF and PFF models (p < .001 for both). The correlation between fτCFF and τCFF was moderately high (r s = 0.63; p < .001), whereas that between fτPFF and τPFF was weaker (r s = 0.40; p = .009). Significance: Our results suggest that using non-invasive ABP for estimation of τ is inaccurate in head injury patients

Relationship Between Baroreflex and Cerebral Autoregulation in Patients With Cerebral Vasospasm After Aneurysmal Subarachnoid Hemorrhage.

Introduction: Common consequences following aneurysmal subarachnoid hemorrhage (aSAH) are cerebral vasospasm (CV), impaired cerebral autoregulation (CA), and disturbance in the autonomic nervous system, as indicated by lower baroreflex sensitivity (BRS). The compensatory interaction between BRS and CA has been shown in healthy volunteers and stable pathological conditions such as carotid atherosclerosis. The aim of this study was to investigate whether the inverse correlation between BRS and CA would be lost in patients after aSAH during vasospasm. A secondary objective was to analyze the time-trend of BRS after aSAH. Materials and Methods: Retrospective analysis of prospectively collected data was performed at the Neuro-Critical Care Unit of Addenbrooke's Hospital (Cambridge, UK) between June 2010 and January 2012. The cerebral blood flow velocity (CBFV) was measured in the middle cerebral artery using transcranial Doppler ultrasonography (TCD). The arterial blood pressure (ABP) was monitored invasively through an arterial line. CA was quantified by the correlation coefficient (Mxa) between slow oscillations in ABP and CBFV. BRS was calculated using the sequential cross-correlation method using the ABP signal. Results: A total of 73 patients with aSAH were included. The age [median (lower-upper quartile)] was 58 (50-67). WFNS scale was 2 (1-4) and the modified Fisher scale was 3 (1-3). In the total group, 31 patients (42%) had a CV and 42 (58%) had no CV. ABP and CBFV were higher in patients with CV during vasospasm compared to patients without CV (p = 0.001 and p < 0.001). There was no significant correlation between Mxa and BRS in patients with CV, neither during nor before vasospasm. In patients without CV, a significant, although moderate correlation was found between BRS and Mxa (rS = 0.31; p = 0.040), with higher BRS being associated with worse CA. Multiple linear regression analysis showed a significant worsening of BRS after aSAH in patients with CV (R p = -0.42; p < 0.001). Conclusions: Inverse compensatory correlation between BRS and CA was lost in patients who developed CV after aSAH, both before and during vasospasm. The impact of these findings on the prognosis of aSAH should be investigated in larger studies

Metody analizy i oceny bezpieczeństwa oraz jakości informacji

Praca recenzowana / Peer-reviewed paperTematyka monografii koncentruje się na metodach zapewnienia bezpieczeństwa informacji, procedurach wspomagających podnoszenie jakości danych oraz narzędziach zwiększających możliwości pozyskiwania z dostępnych informacji wartościowych i rzetelnych wniosków analitycznych. Publikacja podzielona jest na trzy części. Pierwsza część zawiera 3 rozdziały, w których podjęto kwestie zapewnienia bezpieczeństwa informacji. Druga część monografii, ujęta w kolejnych trzech rozdziałach, prezentuje wybrane narzędzia i modele organizacji zasobów cyfrowych mających na celu zapewnienie wysokiej jakości, użyteczności oraz wiarygodności zbiorów danych zawartych w repozytoriach. Ostatnia część pracy przedstawia problematykę związaną z prawem Benforda, pozwalającym ocenić stopień rzetelności danych na podstawie analizy rozkładów cyfr w liczbach weryfikowanego zbioru danych

Applying time-frequency analysis to assess cerebral autoregulation during hypercapnia.

OBJECTIVE: Classic methods for assessing cerebral autoregulation involve a transfer function analysis performed using the Fourier transform to quantify relationship between fluctuations in arterial blood pressure (ABP) and cerebral blood flow velocity (CBFV). This approach usually assumes the signals and the system to be stationary. Such an presumption is restrictive and may lead to unreliable results. The aim of this study is to present an alternative method that accounts for intrinsic non-stationarity of cerebral autoregulation and the signals used for its assessment. METHODS: Continuous recording of CBFV, ABP, ECG, and end-tidal CO2 were performed in 50 young volunteers during normocapnia and hypercapnia. Hypercapnia served as a surrogate of the cerebral autoregulation impairment. Fluctuations in ABP, CBFV, and phase shift between them were tested for stationarity using sphericity based test. The Zhao-Atlas-Marks distribution was utilized to estimate the time-frequency coherence (TFCoh) and phase shift (TFPS) between ABP and CBFV in three frequency ranges: 0.02-0.07 Hz (VLF), 0.07-0.20 Hz (LF), and 0.20-0.35 Hz (HF). TFPS was estimated in regions locally validated by statistically justified value of TFCoh. The comparison of TFPS with spectral phase shift determined using transfer function approach was performed. RESULTS: The hypothesis of stationarity for ABP and CBFV fluctuations and the phase shift was rejected. Reduced TFPS was associated with hypercapnia in the VLF and the LF but not in the HF. Spectral phase shift was also decreased during hypercapnia in the VLF and the LF but increased in the HF. Time-frequency method led to lower dispersion of phase estimates than the spectral method, mainly during normocapnia in the VLF and the LF. CONCLUSION: The time-frequency method performed no worse than the classic one and yet may offer benefits from lower dispersion of phase shift as well as a more in-depth insight into the dynamic nature of cerebral autoregulation

Metody i narzędzia zapisu i udostępniania danych

Praca recenzowana / Peer-reviewed paperPrzekazujemy czytelnikowi kolejną monografię wydaną w ramach serii „Informatyka”, zawierającą publikacje pracowników związanych z Wydziałem Zarządzania i Komunikacji Społecznej Krakowskiej Akademii im. Andrzeja Frycza Modrzewskiego z obszaru problemów optymalizacji, systemów informacyjnych oraz kształcenia zdalnego. Wśród autorów niniejszej publikacji znajdują się głównie pracownicy Studium Informatyki Krakowskiej Akademii i Katedry Informatyki Stosowanej. Opublikowane artykuły są wynikiem współpracy w zespołach z pracownikami innych krakowskich uczelni. Tematyka monografii koncentruje się na metodach optymalizacji, zastosowaniach systemów informatycznych, oraz kształcenia zdalnego. Całość tematyki podzielona jest na trzy wzajemnie powiązane części. Pierwsza część zawiera trzy podrozdziały, w których podjęto kwestie kształcenia zdalnego. Druga część monografii, ujęta w kolejnych trzech podrozdziałach, prezentuje wybrane narzędzia i modele optymalizacji. Ostatnia, trzecia – przedstawia problematykę związaną z zastosowaniem systemów informatycznych w firmie

The relationship between the time of cerebral desaturation episodes and outcome in aneurysmal subarachnoid haemorrhage: a preliminary study.

In this preliminary study we investigated the relationship between the time of cerebral desaturation episodes (CDEs), the severity of the haemorrhage, and the short-term outcome in patients with aneurysmal subarachnoid haemorrhage (aSAH). Thirty eight patents diagnosed with aneurysmal subarachnoid haemorrhage were analysed in this study. Regional cerebral oxygenation (rSO2) was assessed using near infrared spectroscopy (NIRS). A CDE was defined as rSO2 < 60% with a duration of at least 30 min. The severity of the aSAH was assessed using the Hunt and Hess scale and the short-term outcome was evaluated utilizing the Glasgow Outcome Scale. CDEs were found in 44% of the group. The total time of the CDEs and the time of the longest CDE on the contralateral side were longer in patients with severe versus moderate aSAH [h:min]: 8:15 (6:26-8:55) versus 1:24 (1:18-4:18), p = 0.038 and 2:05 (2:00-5:19) versus 0:48 (0:44-2:12), p = 0.038. The time of the longest CDE on the ipsilateral side was longer in patients with poor versus good short-term outcome [h:min]: 5:43 (3:05-9:36) versus 1:47 (0:42-2:10), p = 0.018. The logistic regression model for poor short-term outcome included median ABP, the extent of the haemorrhage in the Fisher scale and the time of the longest CDE. We have demonstrated that the time of a CDE is associated with the severity of haemorrhage and short-term outcome in aSAH patients. A NIRS measurement may provide valuable predictive information and could be considered as additional method of neuromonitoring of patients with aSAH