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Biomedical subjects

L Henriksen

Publications and source records attributed to L Henriksen.

At least 19 recordsLinked to original sources
PubMed1992

Effect of ketanserin on global cerebral blood flow and cerebral oxygen metabolism during midazolam-fentanyl or isoflurane anaesthesia.

We have studied the effect of ketanserin on cerebral blood flow (CBF), cerebral oxygen metabolism (CMRO2) and cerebrovascular carbon dioxide reactivity in 19 adult patients undergoing lumbar disc operation--10 during midazolam-fentanyl anaesthesia (group A) and nine during isoflurane anaesthesia (group B). Measurements were made in each patient whilst awake, during anaesthesia, during anaesthesia with ketanserin and during anaesthesia with ketanserin and hyperventilation. CBF was measured by the i.v. xenon-133 technique. CMRO2 was calculated as the product of CBF and the cerebral arterio-venous oxygen content difference. In the awake state, CBF was 52 and 51 ml/100 g min-1 and CMRO2 3.8 and 3.5 ml/100 g min-1 in groups A and B, respectively. After induction of anaesthesia, CBF decreased 37% in group A and 22% in group B (P < 0.05); CMRO2 decreased 26% in group A and 51% in group B (P < 0.05). Adding ketanserin did not change CBF or CMRO2 in either group. The carbon dioxide reactivity of the cerebral vessels during anaesthesia with ketanserin was 15.4% kPa-1 in group A and 24% kPa-1 in group B. We concluded that ketanserin, in a clinically recommended dose, administered during midazolam-fentanyl or isoflurane anaesthesia had no effect on global CBF, CMRO2 or the relationship between the two factors. Cerebrovascular carbon dioxide reactivity was preserved.

Adult↗
PubMed1990

Focal cerebral dysfunction in developmental learning disabilities.

In 24 children with developmental learning disabilities and 15 age-matched controls regional cerebral activity was studied with xenon-133 single photon emission tomography. In the 9 children with pure attention deficit and hyperactivity disorder (ADHD), the distribution of regional cerebral activity was abnormal--low in striatal and posterior periventricular regions and high in occipital regions. Low activity in striatal and posterior periventricular areas was also seen in the 8 children with ADHD in combination with phonologic-syntactic dysphasia. 7 children with dysphasia, but without hyperactive behaviour, had low cerebral activity in left temporofrontal regions.

Adolescent↗
PubMed1990

Redistribution of cerebral activity during childhood.

Data on the functional development of brain structures in early childhood are scarce. Cognition changes markedly from pre-school age to school age, and we thought it of interest to examine the level of functional activity of selected brain regions. Nine preschool children were studied and compared with eight school children and eighteen adults. Xe133 emission tomography was used for determination of regional cerebral blood flow (rCBF). It was demonstrated that activity in the striatal regions is low in early childhood. In school age the proportion of flow to these regions is increased by about 11-14 per cent (difference between medians). Perfusion of the occipital lobes decreased with age when studied with open eyes and closed eyes, possibly reflecting loss of synapses and decreased plasticity.

Adolescent↗
PubMed1990

Regional cerebral blood flow in chronic alcoholics measured by single photon emission computerized tomography.

Regional cerebral blood flow (CBF) was measured by single photon emission computerized tomography of inhaled 133-Xe in 20 chronic alcoholic men. Mean CBF was 51 ml/(100 g x min) compared with 53 ml/(100 g x min) in 20 normals. Reduced cerebellar blood flow correlated both to structural abnormalities seen on CT scan and to cognitive dysfunction. Slight abnormalities of the regional CBF was observed in the alcoholics. They had a higher incidence of regional low flow areas than a control group. Low flow areas were found in frontal and posterior parts of the brain not only in patients with atrophia, but also in patients without CT abnormalities, suggesting neuronal dysfunction. The occurrence of regional low flow areas was associated with the severity of alcoholism, cerebral atrophy and intellectual impairment.

Adult↗
PubMed1989

Striatal dysfunction in attention deficit and hyperkinetic disorder.

We have previously reported that periventricular structures are hypoperfused in attention deficit and hyperactivity disorder (ADHD). This study has expanded the number of patients, who were divided into two groups: six patients with pure ADHD, and 13 patients with ADHD in combination with other neurologic symptoms. By using xenon 133 inhalation and emission tomography, the regional cerebral blood flow distribution was determined and compared with a control group. Striatal regions were found to be hypoperfused and, by inference, hypofunctional in both groups. This hypoperfusion was statistically significant in the right striatum in ADHD, and in both striatal regions in ADHD with other neuropsychologic and neurologic symptoms. The primary sensory and sensorimotor cortical regions were highly perfused. Methylphenidate increased flow to striatal and posterior periventricular regions, and tended to decrease flow to primary sensory regions. Low striatal activity, partially reversible with methylphenidate, appears to be a cardinal feature in ADHD.

Attention Deficit Disorder with Hyperactivity↗
PubMed1989

Intellectual impairment with regional cerebral dysfunction after low neonatal cerebral blood flow.

12 children, in whom neonatal CBF had been measured, were examined at the age of 9 to 10 years by means of clinical neurological examination, neuropsychologic tests and observations, and 133Xe single photon emission computed tomography (SPECT). Performance on most neuropsychologic tests or observations correlated with neonatal CBF but only rarely with other neonatal parameters (birthweight, gestational age, Apgar score at 5 min). Poor performance on each test or observation was in most instances correlated with a distinct pattern of regional cerebral dysfunction as assessed by SPECT. The dysfunctional region tended to be located periventricularly and in the watershed regions between major cerebral arteries. It is concluded that low neonatal cerebral perfusion may be an indicator, and possibly a determinant, of later intellectual dysfunction in stressed neonates, and that specific neuropsychologic deficits are associated with specific patterns of cerebral dysfunction in the present patient group.

Brain Diseases↗
PubMed1988

Percutaneous transluminal angioplasty of the superficial femoral artery by retrograde catheterization via the popliteal artery.

We report the results of 50 angioplasty procedures via the popliteal artery. A 3-year follow-up including control of blood pressures at ankle and toe levels show results comparable to reports in the literature. This new approach for angioplasty of the superficial femoral artery and eventually of coexisting iliac lesions enables treatment of previously inaccessible lesions. The technique is especially suited for lesions close to the takeoff of the superficial femoral artery.

Aged↗
PubMed1986

Brain luxury perfusion during cardiopulmonary bypass in humans. A study of the cerebral blood flow response to changes in CO2, O2, and blood pressure.

CBF and related parameters were studied in 68 patients before, during, and following cardiopulmonary bypass. CBF was measured using the intraarterial 133Xe injection method. The extracorporeal circuit was nonpulsatile with a bubble oxygenator administering 3-5% CO2 in the main group of hypercapnic patients (n = 59) and no CO2 in a second group of hypocapnic patients. In the hypercapnic patients, marked changes in CBF occurred during bypass. Evidence was found of a brain luxury perfusion that could not be related to the effect of CO2 per se. Mean CBF was 29 ml/100 g/min just before bypass, 49 ml/100 g/min at steady-state hypothermia (27 degrees C), reached a maximum of 73 ml/100 g/min during the rewarming phase (32 degrees C), fell to 56 ml/100 g/min at steady-state normothermic bypass (37 degrees C), and was 48 ml/100 g/min shortly after bypass was stopped. Addition of CO2 evoked systemic vasodilation with low blood pressure and a rebound hyperemia. The hypocapnic group responded more physiologically to the induced changes in hematocrit (Htc) and temperature, CBF being 25, 23, 25, 34, and 35 ml/100 g/min, respectively, during the five corresponding periods. Carbon dioxide was an important regulator of CBF during all phases of cardiac surgery, the responsiveness of CBF being approximately 4% for each 1-mm Hg change of PaCO2. The level of MABP was important for the CO2 response. At low blood pressure states, the CBF responsiveness to changes in PaCO2 was almost abolished. An optimal level of PaCO2 during hypothermic bypass of approximately 25 mm Hg (at actual temperature) is recommended. A normal autoregulatory response of CBF to changes in blood pressure was found during and following bypass. The lower limit of autoregulation was at pressure levels of approximately 50-60 mm Hg. CBF autoregulation was almost abolished at PaCO2 levels of greater than 50 mm Hg. The degree of hemodilution neither affected the CO2 response nor impaired CBF autoregulation, although, as would be expected, it influenced CBF: In 33 women CBF was 55 ml/100 g/min at an Htc of 24%, as compared with 42 ml/100 g/min in 35 men (Htc = 28%). High PaO2 was a vasoconstrictor, the autoregulatory plateau being narrowed. The lower limit of autoregulation was shifted to a higher pressure when PaO2 was low.

Adult↗
PubMed1986

Cerebral blood flow during early cardiopulmonary bypass in man. Effect of procaine in cardioplegic solutions.

Cerebral blood flow (CBF), plasma procaine concentrations, and somatosensory evoked potentials (SSEP) were recorded in 2 groups of patients in whom either a high-procaine cardioplegic solution (Bretschneider's n = 29), or a low-procaine cardioplegic solution (St. Thomas', n = 13) was used. In the Bretschneider's group, marked changes in CBF occurred (p less than 0.001). Mean CBF was 27 (range 18 to 51) ml/(100 g X min) between sternotomy and the onset of extracorporeal circulation (ECC). A mean of 6 minutes after the onset of ECC, and before the administration of Bretschneider's cardioplegic solution, CBF increased to 39 ml/(100 g X min). After administration of the cardioplegic solution, CBF decreased significantly within the first 15 minutes, and then gradually increased to a mean of 68 (range 43 to 108) ml/(100 g X min). Cerebral blood flow was 45 ml/(100 g X min) just after ECC was stopped. Marked plasma procaine concentrations, up to 100 mg/l, were reached just after the infusion of Bretschneider's solution. The flow was significantly reduced (p less than 0.015) in patients with plasma procaine greater than or equal to 10 mg/l, when compared to patients with plasma procaine values less than 10 mg/l. In the St. Thomas' cardioplegic solution group the same reduction in CBF did not occur (p less than 0.02). Despite the depressant effect of procaine on CBF in the Bretschneider group, a consistent brain hyperperfusion was observed in all patients during hypothermic ECC if their blood pressure was sufficient to produce hyperemia. In rats (n = 6), during normothermia without extracorporeal circulation, the effect of procaine was much more pronounced. The CBF fell from a mean resting level of 108 ml/(100 g X min) to 68 and 54 ml/(100 g X min) after 15 and 35 minutes, respectively, of continuous infusion of Bretschneider's solution. The flow returned to the resting level about 40 minutes after termination of the infusion.

Adult↗
PubMed1986

Cerebral blood flow during cardiopulmonary bypass in man: effect of arterial filtration.

Cerebral blood flow was recorded in 39 patients undergoing cardiac surgery by intraarterial injection of xenon 133. There were three subgroups of patients: 10 patients had a 20 micron arterial filter (Johnson) and 11 a 40 micron filter (Pall), and 18 had no arterial filtration. All patients had a 40 micron (Pall) filter in the coronary suction line. Significant changes in cerebral blood flow occurred during extracorporeal circulation (p less than 0.0001). For all patients cerebral blood flow increased from a resting prebypass level of 30 to 46 and 57 ml/100 g a minute during initial and stable hypothermic extracorporeal circulation respectively. Both measurements were obtained at 26 degrees C and the recordings were made on average 12 and 55 minutes after the extracorporeal circulation was started. During rewarming cerebral blood flow increased to 64, 53, 41, and 36 ml/g a minute at 31 degrees, 33 degrees, 35 degrees, and 37 degrees C respectively, and when measured four and 16 minutes on average after bypass it was 44 and 41 ml/100 g a minute. This general brain hyperperfusion was noticed in all patients with a high enough mean blood pressure to produce hyperaemia. Interposing 20 and 40 micron arterial filters reduced cerebral blood flow but did not prevent this hyperaemia. The cerebral autoregulation, which maintains a constant cerebral blood flow within wide limits of perfusion pressures, was not affected by arterial filtration. The lower limit of blood pressure at which a further reduction in blood pressure was followed by a reduction in cerebral blood flow was around 60 mm Hg in all three groups.

Adult↗
PubMed1985

Observations on regional cerebral blood flow in cortical and subcortical structures during language production in normal man.

Regional cerebral blood flow (rCBF) was studied by single photon emission computerized tomography (SPECT) of inhaled xenon-133 in six normal volunteers during various language, articulatory, and control conditions. Language production increased rCBF in predominantly left-sided cortical and subcortical areas. The involved regions were anatomically related to a left frontal area (Broca's), to both caudate nuclei, to a left thalamic/pallidal area, and bilaterally in retrorolandic areas. The failure to demonstrate lateralized retrorolandic activity is thought to reflect the complexity of the tasks.

Adult↗
PubMed1985

Regional cerebral blood flow in hemiparkinsonian patients. Emission computerized tomography of inhaled 133Xenon before and after levodopa.

Regional and mean cerebral blood flow (rCBF, CBF) were measured by tomography of inhaled 133Xe in 18 hemiparkinsonian patients before and after levodopa (L-dopa). Baseline mean CBF was 55 ml/ (100 g X min) after an L-dopa-free interval of at least 10 h (range 10-13) and remained unchanged at 56.1 ml/ (100 g X min) after optimal clinical improvement was achieved by L-dopa. However, L-dopa reduced rCBF significantly (P less than 0.05) in the striatum contralateral to the symptomatic limbs. In patients with adverse reactions such as hyperkinesias and on/off symptoms, flow tended to increase bilaterally in striatum and often markedly in midline structures anatomically related to globus pallidus and thalamus. Compared with a normal population, the subcortical rCBF distribution was asymmetrical with a reduced flow (-18%) in the striatum contralateral to the symptomatic limbs and in midline structures anatomically related to globus pallidus and thalamus (-12%). Cortical CBF was inverse related to the duration of Parkinson's disease (P less than 0.05), probably reflecting an increasing mental deterioration with time.

Adult↗
PubMed1984

Evidence suggestive of diffuse brain damage following cardiac operations.

In 37 patients regional cerebral blood flow (rCBF) was measured by single photon emission computerised tomography (SPECT) after inhalation of xenon-133 before and within the first 10 days after open heart surgery for acquired or congenital heart disease. None of the patients had motor deficits postoperatively and no focal abnormalities were disclosed by the rCBF tomograms. However, rCBF was generally reduced and mean CBF fell from a normal value of 53.5 to 44.7 ml/100 g X min (p less than 0.001). Changes in rCBF occurred uniformly throughout the brain. The reduction in CBF correlated positively with increasing years (p less than 0.05), duration of extracorporeal circulation (p less than 0.05), and low mean arterial blood pressure during the bypass (p less than 0.02). It was generally more pronounced after valve replacement than after coronary bypass (p less than 0.16). In 11 patients investigated 1 year after surgery CBF remained slightly reduced, 50.5 ml/100 g X min (p less than 0.05). No CBF reduction occurred in a control group of 15 patients who underwent carotid endarterectomy or extracranial-intracranial shunt operations. The findings are consistent with the suggestion that the extracorporeal circulation causes early postoperative central nervous system dysfunction.

Adult↗
PubMed1976

Local reflex in microcirculation in human cutaneous tissue.

Blood flow in cutaneous tissue measured by the local 133Xenon washout technique decreased about 35 per cent during venous stasis of 40 mmHg in three normal subjects. The response was unaffected by block of the nerve three cm proximally to the labeled area. When the tissue was infiltrated with lidocaine or with phentolamine, blood flow remained constant, indicating that the decrease in blood flow is due to an arteriolar vasoconstrictor response to increase in venous transmural pressure. Local venous stasis elicited a vasoconstrictor response in an adjoining area not affected by the stasis. The response was blocked by lidocaine applied to the side of stasis. In 2 chronically sympathectomized patients, the vasoconstrictor response was abolished in the denervated limbs but present on the non-operated side (1 patient with unilateral sympathectomy). The results indicate that the vasoconstrictor response to an increase in venous transmural pressure is due to a local nervous mechanism involving sympathetic adrenergic fibres, most likely a sympathetic axon reflex.

Blood Pressure↗