Browsing by Subject "middle cerebral artery"

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    The Effect of Hyperventilation on the Increase of Cerebral Blood Flow Velocity Secondary to Deflation of the Tourniquet in Lower Extremity Surgery; [Alt Ekstremite Cerrahisinde Turnike Açilmasina Sekonder Beyin Kan Akim Hizi Artişina Hiperventilasyonun Etkisi]
    (2003) Sakarya M.; Topçu I.; Özkol M.; Yentür A.; Yercan H.; Okçu G.
    We aimed to investigate the effects of hyperventilation on cerebral blood flow (CBF) in order to maintain normocapnia following the deflation of the tourniquet in patients undergoing elective lower extremity operation during intravenous general anesthesia (TIVA). In all cases(n=15), anaesthesia was induced by 2 mg kg-1 propofol, 1 μg kg-1 remifentanyl and 1 mg kg-1 vecuronium, and was maintained with the mixture of 50 % air-O2, 6-8 mg kg-1 dk-1 propofol and 0.5 μg kg-1 dk-1 remifentanyl infusions. Patients were randomized into two groups. Group I (n=7) was ventilated by f=10/min and V T=8 mL kg-1. Patients in group II (n=8) were ventilated similarly as group I until the deflation of tourniquet, and following deflation by increasing respiratory frequency adjusted to maintain end-tidal CO 2 (PETCO2) between 30-35 mmHg. Middle cerebral artery (MCA) flow velocity was measured by transcranial Doppler ultrasonography as mean (m-MCA) and peak (p-MCA) values. Data were recorded 5 minutes before tourniquet deflation (control), and every minute in the first 10 minutes following deflation While there has been no difference for p-MCA, m-MCA and PaCO2 in group II, significant increases (p<0.05) in mean MCA flow velocity were obtained in 2nd, 3rd and 4th minutes in group I. Maximum increase was obtained in 3rd minute and determined as 52±7 cm/sec. The increases of PaCO2 were obtained in 2 to 6 minutes (p<0.05) and maximum level was 41±1 mmHg (25 %±3 %) in 3rd minute. We concluded that, the increase of MCA flow velocity and CBF related to the increase of PaCO2 after deflation of the pneumatic tourniquet may be prevented by maintaining normocapnia provided by increasing minute ventilation.
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    Effect of Propofol and Clonidine on Cerebral Blood Flow Velocity and Carbon Dioxide Reactivity in the Middle Cerebral Artery
    (2004) Mirzai H.; Tekin I.; Tarhan S.; Ok G.; Goktan C.
    This study was designed to evaluate the effects of propofol alone and propofol-clonidine combination on human middle cerebral artery blood flow velocity (Vmca) and cerebrovascular carbon dioxide (CO2) response by using transcranial Doppler ultrasonography. Mean Vmca in response to changes in arterial partial pressure of CO2 (PaCO2) was determined under the following conditions: awake (group 1), propofol anesthesia (group 2), and combined propofol-clonidine anesthesia (group 3). Normocapnic, hypercapnic, and hypocapnic values of heart rate, mean arterial pressure, partial end-tidal CO2 pressure, PaCO2, and Vmca were obtained. The mean Vmca in groups 2 and 3 was significantly lower than that in group 1 at each level of PaCO2. The calculated Vmca at each level of PaCO 2 was not different between groups 2 and 3. There was a correlation between PaCO2 and Vmca in all groups, but in the anesthetized groups the effect of PaCO2 on Vmca was attenuated. The present data demonstrated that clonidine-propofol does not change CO2 reactivity compared with propofol alone, but both anesthetics attenuate cerebral blood flow compared with awake controls.
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    Assessment of fetal cerebral arterial and venous blood flow before and after vaginal delivery or Cesarean section
    (2004) Baytur Y.B.; Tarhan S.; Uyar Y.; Ozcakir H.T.; Lacin S.; Coban B.; Inceboz U.; Caglar H.
    Objectives: To compare perinatal intracranial arterial and venous blood velocity changes between healthy term neonates delivered vaginally or by Cesarean section and to correlate these changes with cord blood gases and pH values at birth. Methods: The study involved 43 healthy term neonates who were delivered vaginally (n = 20) or by Cesarean section (n = 23). All fetuses/neonates were examined by Doppler ultrasound to obtain middle cerebral artery (MCA) and cerebral transverse sinus (Tsin) Doppler waveforms on three occasions (before delivery, and 1 h and 24 h after birth). Pulsatility index (PI) and peak systolic velocity (PSV) for MCA and Tsin were measured and compared between neonates who were delivered vaginally or by Cesarean section. Umbilical cord blood samples were analyzed for umbilical artery and vein pH, pO2 and pCO2 and values were correlated with MCA and Tsin Doppler indices. Results: MCA-PI increased and MCA-PSV decreased at 1 h after birth, and Doppler measurements returned to predelivery values at 24 h after birth. Tsin Doppler measurements remained unchanged at 1 h and 24 h when compared to predelivery values in both the Cesarean and vaginal delivery groups. There was a negative correlation between Tsin-PI before birth and umbilical venous pH. There was a positive correlation between Tsin-PSV at 1 h after birth and umbilical vein pCO2. Conclusions: Cerebral arterial blood velocity decreases immediately after birth and increases within 24 h probably as part of neonatal adaptation. Cerebral venous blood velocity remains constant during the perinatal period and is likely to be regulated in a different and more complex manner than that of arterial blood velocity. Mode of delivery does not affect cerebral blood velocity. Copyright © 2004 ISUOG.
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    Effects of different postmenopausal hormone therapy regimens on cerebral blood flow and cognitive functions
    (2009) Guvenal T.; Durna A.; Erden O.; Guvenal F.; Cetin M.; Cetin A.
    Introduction: The purpose of this study was to compare the effects of different postmenopausal hormone therapy regimens, namely conjugated equine estrogens (CEE), CEE plus medroxyprogesterone acetate (MPA), tibolone, and raloxifene on cerebral blood flow and cognitive functions. Methods: A total of 64 healthy postmenopausal women admitted to the Department of Obstetrics and Gynecology, Cumhuriyet University, Turkey were included in this study. Patients were divided into five groups with respect to the treatment protocols: CEE 0.625 mg/day (n=13); CEE 0.625 mg/day + MPA 2.5 mg/day (n=14); tibolone 2.5 mg/day (n=11); raloxifene 60 mg/day (n=9); and control (n=17). The CEE group included only women with surgical menopause. Those who were on hormonal therapy, who had previously used hormonal therapy, who had neurological disorders, or who did not accept the longterm follow-up were excluded from the study. Demographic and clinic characteristics were recorded. Before starting the therapy regimens, cerebral blood flow was evaluated by internal carotid artery and middle cerebral artery peak systolic velocity, and pulsatility index measurements via Doppler ultrasonography. Cognitive functions were evaluated by the Standardized Mini-Mental Test. The mean follow-up period was 10.9±2.4 months, ranging between 8 and 16 months. After the follow-up period, the cerebral blood flow, and cognitive function of each woman was re-evaluated. Results: Demographic and clinical characteristics of the women were not significantly different between the study groups (P>0.05). There were no significant differences between the pretreatment and posttreatment values for cerebral blood flow indices and cognitive function scores in any of the study groups (P>0.05). Conclusion: Different postmenopausal hormone therapy regimens have not revealed any significant effects on either cerebral blood flow or cognitive function. © 2009 Springer Healthcare Communications.
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    A case of antenatal diagnosis and postnatal characteristics of ıdiopathic ınfantile arterial calcification (IIAC and prenatal diagnosis)
    (Taylor and Francis Ltd, 2016) Pala H.G.; Bilgili G.; Artunc Ulkumen B.; Alkan F.; Coskun S.
    [No abstract available]
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    Evaluation of Cerebral Vasomotor Reactivity by Transcranial Doppler Ultrasound in Patients with Diabetic Retinopathy
    (Taylor and Francis Ltd., 2023) Yaman Kula A.; Deniz Ç.; Özdemir Gültekin T.; Altinisik M.; Asil T.
    The aim of this study was to assess the correlation between cerebral vasomotor reactivity (CVR) and the grade of diabetic retinopathy. A total of 43 diabetic patients with matched severity of diabetic retinopathy between their right and left eyes were included in this study. Diabetic retinopathy was graded in three groups. Right and left middle cerebral artery CVR was assessed by the breath-holding index (BHI) using transcranial Doppler ultrasound (TCD). The mean age of the patients was 56.51 ± 9.34 years with a mean duration of having diabetes mellitus of 14.49 ± 8.06 years. Diabetic retinopathy was graded as mild, moderately severe, and severe in 27.9%, 34.9%, and 37.2% of the patients, respectively. The grade of diabetic retinopathy was associated with the HbA1c level (p <.049), microalbuminuria (p <.024), and BHI (p =.001). In patients with severe diabetic retinopathy, the right-sided BHI was significantly lower as compared to those with mild or moderately severe retinopathy (p =.001 and p =.008, respectively). The left-sided BHI value in patients with severe diabetic retinopathy was significantly lower as compared to those with mild or moderately severe retinopathy (p =.001 and p =.012, respectively). In subjects with moderately severe diabetic retinopathy, both-sided BHI was significantly reduced compared to those with mild retinopathy (p =.001). Our results indicate that the grade of diabetic retinopathy was associated with impaired CVR. © 2023 Taylor & Francis Group, LLC.