Zastosowanie nieinwazyjnej metody NIR-T/BSS (Near Infra-Red Transillumination-Back Scattering) do monitorowania zmian ukrwienia mózgu w chirurgii naczyń szyjnych

Wstęp. Z roku na rok zwiększa się liczba zabiegów wykonywanych na tętnicach szyjnych. Dotychczas stosowane metody kontroli zmian ukrwienia mózgu wydają się niewystarczające. Szczególnie dotkliwy jest brak możliwości monitorowania podczas zabiegu operacyjnego. Cel pracy. Wykazanie przydatności nowo opracowanej metody transluminacji w bliskiej podczerwieni (NIR-T/BSS) do monitorowania zmian ukrwienia mózgu podczas zabiegu operacyjnego endarterektomii, oceny jego skuteczności, jak również do wspomagania diagnostyki przed zabiegiem. Materiał i metody. Badaniem objęto 50 chorych ze zwężeniem tętnicy szyjnej, u których wykonano zabieg endarterektomii. Wyniki. Zastosowanie metody NIR-T/BSS pozwoliło obiektywnie ocenić krążenie oboczne, wybrać kolejność stron w przypadku zabiegów obustronnych przy takim samym stopniu zwężenia, określonym metodą opartą na efekcie Dopplera, monitorować zmiany ukrwienia mózgu podczas zabiegu operacyjnego oraz ocenić poprawę ukrwienia mózgu po zabiegu. Wnioski. Wstępna ocena wyników uzyskanych za pomocą metody NIR-T/BSS pozwala uznać ją za bardzo przydatną metodę nieinwazyjnego monitorowania zmian ukrwienia mózgu. Technika ta jest łatwa do zastosowania w warunkach operacyjnych, charakteryzuje się wysoką czułością, a otrzymane wyniki korelują z wynikami uzyskanymi innymi metodami (np. Dopplera) oraz z procedurą zabiegu. Przedstawione zapisy mają charakter jakościowy.Background. A steady rising trend is observed in the number of carotid surgeries performed. Methods of monitoring of changes in cerebral blood supply used so far, prove inadequate and insufficient. Of special importance and value would be availability of such monitoring during carotid surgery. Aim of the study. The objective of the current study was evaluation of the applicability and usefulness of a newly devised non-invasive method of Near Infra-Red Transillumination/Backscattering Sounding (NIR-T/BSS) for monitoring of changes in cerebral blood supply in the course of carotid endarterectomy and for assessment of the effectiveness of the surgery, as well as a supplementary diagnostic tool prior to surgical treatment. Material and methods. NIR-T/BSS recordings were made in 50 patients with recognised carotid stenosis, in whom surgical treatment with carotid endarterectomy was performed. Results. Application of the NIR-T/BSS method enabled: A. objective assessment of the collateral circulation, B. selection of the sequence of sides to be operated on in cases of equal bilateral carotid stenosis, as determined with Doppler ultrasound, C. monitoring of the changes in cerebral blood supply during the surgery, and D. post-operative evaluation of the beneficial effect of the surgery.   Conclusions. The early results obtained with the NIR-T/BSS method provide arguments to believe that this method will soon be recognised as highly useful modality in monitoring of the changes in cerebral blood supply. The technique is characterised by high simplicity of use in intra-operative conditions, high sensitivity and congruence of the obtained results with those collected with other methods, as well as with the logic of the physiological reactions. The presented NIR-T/BSS recordings provide qualitative and not quantitative arguments

Próba Valsavy zwiększa czułość składowej przywspółczulnej odruchu spowodowanego odbarczeniem baroreceptorów u młodych zdrowych osób

Introduction. The objective was to verify the hypothesis that change in cardiovagal baroreceptor unload reflex sensitivity occurs between early phase 2 (VM2E) and phase 3 (VM3) of the Valsalva manoeuvre (VM). The study was performed on 29 volunteers between the ages of 25 and 40 (29.3 ± SE 4.0). Material and methods. The experimental scheme was as follows: rest in sitting position, VM in sitting position maintaining an expiratory pressure of 20 mm Hg for 15 seconds, rest in sitting position. Changes in systolic blood pressure (SBP), diastolic blood pressure (DBP) and heart rate (HR) were measured using Finapres. Results. In VM2E and VM3, HR increased (+51.76 ± SE 4.06 beats/min., p < 0.001; +37.77 ± SE 8.65 beats/min., p < 0.0001, respectively) in response to a fall in SBP (–47.55 ± SE 3.95 mmHg, p < 0.001; –29.66 ± SE 2.80 mmHg, p < 0.0001; respectively). Both events of baroreceptor unload have been observed within the very similar range of SBP and HR. Conclusion. The slope of regression relating change in heart rate (DHR) and systolic arterial pressure (DSBP) was significantly higher in VM3 (DHR2 = –1.063 × DSBP2 + 7.0986) than in VM2E (DHR1 = –0.4395 × DSBP2 + 30.862), suggesting the increased baroreceptors’ sensitivity toward SBP fall in VM3 compared to VM2E. VM increases vagal baroreceptor unloads reflex sensitivity.Wstep. Celem badania było zweryfikowanie hipotezy, że zmiana czułości składowej kardiowagalnej odruchu z baroreceptorów występuje między wczesną fazą 2 (VM2E) a fazą 3 (VM3) próby Valsalvy (VM, Valsalva manoeuvre). Materiał i metody. Badanie przeprowadzono w grupie 29 ochotników w wieku 25–40 lat (29,3 ± błąd standardowy średniej [SE, standard error of the mean] 4,0). Eksperyment przeprowadzono według następującego schematu: odpoczynek w pozycji siedzącej, VM w pozycji siedzącej, utrzymując ciśnienie wydechowe na poziomie 20 mm Hg przez 15 sekund, odpoczynek w pozycji siedzącej. Za pomocą urządzenia Finapres zmierzono zmiany wartości skurczowego ciśnienia tętniczego (SBP, systolic blood pressure), rozkurczowego ciśnienia tętniczego (DBP, diastolic blood pressure) i częstotliwości rytmu serca (HR, heart rate). Wyniki. W trakcie faz VM2E i VM3 nastąpiło zwiększenie HR (odpowiednio +51,76 ± SE 4,06 uderzeń/min; p < 0,001 i +37,77 ± SE 8,5 uderzeń/min; p < 0,0001) w odpowiedzi na zmniejszenie SBP (odpowiednio –47,55 ± SE 3,95 mm Hg; p < 0,001 i –29,66 ± SE 2,80 mm Hg; p < 0,0001). W obu przypadkach odbarczenie baroreceptorów obserwowano w bardzo podobnym zakresie SBP i HR. Wnioski. Nachylenie linii regresji odnoszących się do zmiany częstotliwości rytmu serca (DHR) i skurczowego ciśnienia tętniczego (DSBP) było istotnie większe w fazie VM3 (DHR2 = –1,063 × DSBP2 + 7,0986) niż w fazie VM2E (DHR1 = –0,4395 × DSBP2 + 30,862), co wskazuje na zwiększenie czułości baroreceptorów w stosunku do spadku SBP w fazie VM3 w porównaniu z fazą VM2E. VM zwiększa czułość składowej przywspółczulnej odruchu wywołany odbarczeniem baroreceptorów

Subarachnoid Space: New Tricks by an Old Dog

PURPOSE: The purpose of the study was to: (1) evaluate the subarachnoid space (SAS) width and pial artery pulsation in both hemispheres, and (2) directly compare magnetic resonance imaging (MRI) to near-infrared transillumination/backscattering sounding (NIR-T/BSS) measurements of SAS width changes in healthy volunteers. METHODS: The study was performed on three separate groups of volunteers, consisting in total of 62 subjects (33 women and 29 men) aged from 16 to 39 years. SAS width was assessed by MRI and NIR-T/BSS, and pial artery pulsation by NIR-T/BSS. RESULTS: In NIR-T/BSS, the right frontal SAS was 9.1% wider than the left (p<0.01). The SAS was wider in men (p<0.01), while the pial artery pulsation was higher in women (p<0.01). Correlation and regression analysis of SAS width changes between the back- and abdominal-lying positions measured with MRI and NIRT-B/SS demonstrated high interdependence between both methods (r = 0.81, p<0.001). CONCLUSIONS: NIR-T/BSS and MRI were comparable and gave equivalent modalities for the SAS width change measurements. The SAS width and pial artery pulsation results obtained with NIR-T/BSS are consistent with the MRI data in the literature related to sexual dimorphism and morphological asymmetries between the hemispheres. NIR-T/BSS is a potentially cheap and easy-to-use method for early screening in patients with brain tumours, increased intracranial pressures and other abnormalities. Further studies in patients with intracranial pathologies are warranted

Influence of acute jugular vein compression on the cerebral blood flow velocity, pial artery pulsation and width of subarachnoid space in humans.

PURPOSE: The aim of this study was to assess the effect of acute bilateral jugular vein compression on: (1) pial artery pulsation (cc-TQ); (2) cerebral blood flow velocity (CBFV); (3) peripheral blood pressure; and (4) possible relations between mentioned parameters. METHODS: Experiments were performed on a group of 32 healthy 19-30 years old male subjects. cc-TQ and the subarachnoid width (sas-TQ) were measured using near-infrared transillumination/backscattering sounding (NIR-T/BSS), CBFV in the left anterior cerebral artery using transcranial Doppler, blood pressure was measured using Finapres, while end-tidal CO(2) was measured using medical gas analyser. Bilateral jugular vein compression was achieved with the use of a sphygmomanometer held on the neck of the participant and pumped at the pressure of 40 mmHg, and was performed in the bend-over (BOPT) and swayed to the back (initial) position. RESULTS: In the first group (n = 10) during BOPT, sas-TQ and pulse pressure (PP) decreased (-17.6% and -17.9%, respectively) and CBFV increased (+35.0%), while cc-TQ did not change (+1.91%). In the second group, in the initial position (n = 22) cc-TQ and CBFV increased (106.6% and 20.1%, respectively), while sas-TQ and PP decreases were not statistically significant (-15.5% and -9.0%, respectively). End-tidal CO(2) remained stable during BOPT and venous compression in both groups. Significant interdependence between changes in cc-TQ and PP after bilateral jugular vein compression in the initial position was found (r = -0.74). CONCLUSIONS: Acute bilateral jugular venous insufficiency leads to hyperkinetic cerebral circulation characterised by augmented pial artery pulsation and CBFV and direct transmission of PP into the brain microcirculation. The Windkessel effect with impaired jugular outflow and more likely increased intracranial pressure is described. This study clarifies the potential mechanism linking jugular outflow insufficiency with arterial small vessel cerebral disease

Near-infrared transillumination back scattering sounding--new method to assess brain microcirculation in patients with chronic carotid artery stenosis.

PURPOSE: The purpose of the study was to assess the responses of pial artery pulsation (cc-TQ) and subarachnoid width (sas-TQ) to acetazolamide challenge in patients with chronic carotid artery stenosis and relate these responses to changes in peak systolic velocity (PSV), cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT) and time to peak response (TTP). METHODS: Fifteen patients with carotid artery stenosis ≥ 90% on the ipsilateral side and <50% on the contralateral side were enrolled into the study. PSV was assessed using colour-coded duplex sonography, CBF, CBV, MTT and TTP with perfusion computed tomography, cc-TQ and sas-TQ with near-infrared transillumination/backscattering sounding (NIR-T/BSS). RESULTS: Based on the ipsilateral/contralateral cc-TQ ratio after acetazolamide challenge two groups of patients were distinguished: the first group with a ratio ≥ 1 and the second with a ratio <1. In the second group increases in CBF and CBV after the acetazolamide test were significantly higher in both hemispheres (ipsilateral: +33.0% ± 8.1% vs. +15.3% ± 4.4% and +26.3% ± 6.6% vs. +14.3% ± 5.1%; contralateral: +26.8% ± 7.0% vs. +17.6% ± 5.6% and +20.0% ± 7.3% vs. +10.0% ± 3.7%, respectively), cc-TQ was significantly higher only on the ipsilateral side (+37.3% ± 9.3% vs. +26.6% ± 8.6%) and the decrease in sas-TQ was less pronounced on the ipsilateral side (-0.7% ± 1.5% vs. -10.2% ± 1.5%), in comparison with the first group. The changes in sas-TQ following the acetazolamide test were consistent with the changes in TTP. CONCLUSIONS: The ipsilateral/contralateral cc-TQ ratio following acetazolamide challenge may be used to distinguish patient groups characterized by different haemodynamic parameters. Further research on a larger group of patients is warranted

Linear correlation analysis of cc-TQ and PP change during bilateral jugular vein compression in initial position versus baseline.

<p>All values of cc-TQ and PP obtained from 22 volunteers were included in the analysis of linear correlation (Spearman r = −0.74, p<0.001). cc-TQ – cardiac component of transillumination quotient (pial artery pulsation); PP – pulse pressure; mmHg – millimetres of mercury.</p

Effect of acute bilateral jugular vein compression on NIR-T/BSS variables in the initial position.

<p>1 – sas-TQ, 2 – cc-TQ, 3 – enhanced tracing of the distant sensor (DS) signal (absence of the “cutting” effect and absent sharp edges), 4 – enhanced tracing of cc-TQ (absence of the “cutting” effect and absent sharp edges). sas-TQ – the subarachnoid component of the transillumination quotient (the subarachnoid width); cc-TQ – cardiac component of transillumination quotient (pial artery pulsation); µW/cm² – microwatt/centimetre².</p

Effect of acute bilateral jugular vein compression on NIR-T/BSS variables during BOPT: cc-TQ is “cut” by the narrowing SAS.

<p>Sharp edges of the cc-TQ waves are visible at the distant sensor (DS) and cc-TQ (enhanced tracings). cc-TQ – cardiac component of transillumination quotient (pial artery pulsation); µW/cm² – microwatt/centimetre².</p

Effects of acute bilateral jugular vein compression on sas-TQ, cc-TQ, CBFV, SAP, DAP, PP and HR during the BOPT test (BOPT – JVO; n = 10). Mean values and Standard Deviations (SD) are provided.

<p>All changes are calculated versus preceding values. *p<0.05; **p<0.01; ***p<0.001. sas-TQ – the subarachnoid component of the transillumination quotient (the subarachnoid width); cc-TQ – cardiac component of transillumination quotient (pial artery pulsation); CBFV – cerebral blood flow velocity; SAP – systolic arterial pressure; DAP – diastolic arterial pressure; PP – pulse pressure; HR – heart rate.</p

Effects of acute bilateral jugular vein compression on sas-TQ, cc-TQ, CBFV, SAP, DAP, PP and HR in initial position (Initial – JVO; n = 22).

<p>Mean values and Standard Deviations (SD) are provided. All changes are calculated versus preceding values. *p<0.05; **p<0.01; ***p<0.001. sas-TQ – the subarachnoid component of the transillumination quotient (the subarachnoid width); cc-TQ – cardiac component of transillumination quotient (pial artery pulsation); CBFV – cerebral blood flow velocity; SAP – systolic arterial pressure; DAP – diastolic arterial pressure; PP – pulse pressure; HR – heart rate.</p