Search PubMed⌕ Search

Biomedical subjects

T Lundar

Publications and source records attributed to T Lundar.

At least 55 records · Page 3Linked to original sources
PubMed1990

Hydrocephalus in an achondroplastic child treated by venous decompression at the jugular foramen. Case report.

A 10-month-old child with achondroplasia with progressive head enlargement, ventriculomegaly, and wide subarachnoid spaces over the hemispheres was referred for evaluation. A steady-state lumbar infusion test revealed increased cerebrospinal fluid (CSF) outflow resistance (14 mm Hg/ml/min), and intra-arterial digital subtraction angiography (DSA) demonstrated bilateral venous outflow obstruction due to stenosis of the jugular foramen. Surgical decompression by opening the right jugular foramen relieved the clinical signs of intracranial hypertension. During the following year, the patient's head enlargement was moderate with relative normalization of size. Repeat DSA demonstrated improved venous runoff on the right side, and a steady-state lumbar infusion test demonstrated reduced CSF outflow resistance (10 mm Hg/ml/min). Venous decompression is causal therapy and may prove to be preferable to shunting in children with hydrocephalus and bilateral stenosis of the jugular foramen.

Achondroplasia↗
PubMed1989

[The management of children with hydrocephalus in Norway].

Diversion of ventricular fluid to the right atrium or peritoneum became standard treatment of hydrocephalus in childhood in Norway 25 years ago. Initially we believed that the shunting procedure was only necessary to overcome unwanted dilatation of the ventricles and growth of the head during the first years of life. We now realize that most shunted hydrocephalic children become shunt dependent throughout the rest of their lives. The majority of these children do relatively well and the mortality is negligible. The population of children, teenagers and young adults with indwelling shunts is thus steadily increasing and has reached over one thousand individuals in Norway. Routine use of cerebral CT-scans and X-ray of the shunt system is advocated to improve the routine control of these patients as well as during episodes of shunt failure and other complications of shunt surgery. This population of young shunt treated individuals represents an increasing burden to the small neurosurgical departments as well as the pediatric departments and later on also to the neurological departments. The perspective of life long shunt dependency in most of these children may seem depressing. It should not be forgotten, however, that these young individuals have a benign disorder with potential of good long term prognosis. Adequate resources should therefore be allocated to meet these increasing demands and should be regarded as a good investment.

Cerebrospinal Fluid Shunts↗
PubMed1989

The use of intraventricular resorption tests (IVT) in the management of hydrocephalic children.

Ventricular fluid outflow resistance was determined by steady state infusion of artificial CSF in the lateral ventricle in 35 children in whom the decision for a shunt procedure was judged to be uncertain. Such testing allows direct shunting when found indicated and unnecessary shunting can be avoided. The test was found helpful in 11 children to evaluate the need for continued shunting, assessment of indwelling shunts and establishment of a basis to remove the shunt.

Absorption↗
PubMed1988

EEG and evoked potentials in comatose patients with severe brain damage.

EEGs and evoked potentials were recorded in 76 deeply comatose and unresponsive patients with traumatic or non-traumatic cerebral damage. Spontaneous EEG activity was absent in 37 of the patients on the initial examination. The cortical somatosensory evoked potentials were invariably absent in these patients as were the visual evoked potentials. Brain-stem evoked potentials were abnormal, either lacking all waves or with only wave I or II present. Cerebral angiography performed in 33 of the patients within minutes to a few hours after the neurophysiological examination verified an established brain death, showing full intracerebral circulatory arrest in all. Spontaneous EEG activity was initially present in 32 patients on the first examination, 20 of whom had bilaterally abolished cortical somatosensory potentials. Ten of the patients died a few hours after the initial examination, another 10 were followed for 2-3 days and subsequently developed electrocortical silence (ECS). Twelve of the patients with spontaneous EEG activity had preserved cortical somatosensory potentials, either uni- or bilaterally. The only two who survived were found in this group. In the patients followed with multiple recordings over a few days, the first parameter to indicate a grave prognosis was always disappearance of the cortical somatosensory potentials bilaterally, which generally occurred hours, and sometimes a day or two, before cessation of the spontaneous EEG activity. EEG records from 7 patients did not meet the technical criteria of ECS; all, however, had abolished cortical somatosensory potentials bilaterally, and none in this group survived.

Adolescent↗
PubMed1988

Head injuries during one year in a central hospital in Norway: a prospective study. Epidemiologic features.

Annual age-adjusted incidence rate of head injuries in Akershus County in 1974 was estimated to be 236/100,000, 307/100,000 for males and 164/100,000 for females. The highest incidence rate occurred in males in the age group 10-19 years (489/100,000) and the lowest among females in the age group 30-39 (68/100,000). In all age groups, the incidence rate was higher in males than females. This prospective study included 488 patients, of whom 88.9% had minor head injuries and 11.1% severe head injuries. 16 patients (3.3%) died due to their head trauma. Skull fracture was detected in 10.4% of the patients who survived the first 24 h, and 2.5% had operations. The mean hospital stay was 8.8 days, 10.2 days for the patients injured in traffic accidents and 7.0 days for the others. Besides having a higher incidence rate of head injuries, males suffered severe head injuries more often and their death rate was higher than head-injured females.

Accidents, Traffic↗
PubMed1987

Cerebral perfusion during major cardiac surgery in children.

Six children undergoing major cardiac surgery had extensive cerebral monitoring during cardiopulmonary bypass (CPB). The monitoring included continuous recording of arterial blood pressure (BP), central venous pressure (CVP), cerebral electrical activity by a cerebral function monitor (CFM), and middle cerebral artery (MCA) flow velocity by the transcranial pulsed Doppler (TCD) technique. Introduction of the precooled blood containing priming solution resulted in rapid fall in BP as well as MCA velocities in these children at the start of CPB. During steady-state CPB at 20 degrees C, MCA flow velocities were reduced in five of six children, range 45%-105% of pre-bypass value. These flow velocity values were recorded at cerebral perfusion pressures (CPP = BP - CVP) in the range of 14-26 mmHg. This reduced cerebral perfusion during steady-state CPB appears to be more than sufficient to meet the cerebral metabolic demands at the particular temperature. The reduced cerebral perfusion is in contrast to the enhanced perfusion found in adults during moderately hypothermic (28 degrees-30 degrees C) low-flow, low-pressure CPB previously reported. It was presumably due to the reduced temperature, reduced perfusion pressure, and less hemodilution. During periods of constant temperature, hematocrit, and partial pressure of carbon dioxide (PaCO2), MCA flow velocities varied passively with changes in CPP, demonstrating that cerebral autoregulation was not operative. Transcranial Doppler appears to be a suitable tool for investigating CPB techniques optimal with respect to cerebral circulation.

Blood Flow Velocity↗
PubMed1987

Cerebrovascular effects of isoflurane in man. Intracranial pressure and middle cerebral artery flow velocity.

Twelve hydrocephalic patients undergoing hydrodynamic studies and shunt procedures during general anaesthesia were subjected to short term observations of the cerebrovascular effects of isoflurane. Intraventricular pressure (IVP), arterial pressure (AP); cerebral perfusion pressure (CPP = AP-IVP), end-tidal PCO2, Cerebral Function Monitor (CFM) activity and middle cerebral artery (MCA) flow velocity were measured. Introduction of 1% isoflurane for a 10-min period did not cause significant changes in IVP or MCA flow velocity, but caused marked and significant reductions in arterial pressure and CPP, and increases in CFM activity. In five patients 2% isoflurane was administered for another 5 min before discontinuation of the isoflurane. This caused further significant reduction in arterial pressure and increased IVP in four of the five patients. The decrease in CPP was thus even greater than the reduction in arterial pressure and the CFM activity decreased in four out of five patients. The MCA flow velocity did not change significantly.

Adolescent↗
PubMed1986

Cerebral carbon dioxide reactivity during nonpulsatile cardiopulmonary bypass.

Five patients undergoing extensive cerebral monitoring during cardiopulmonary bypass (CPB) procedures were subjected to studies on cerebral CO2 reactivity during nonpulsatile CPB. The cerebral monitoring included recording of arterial blood pressure (BP), central venous pressure (CVP), epidural intracranial pressure (EDP), cerebral electrical activity by a cerebral function monitor (CFM), and middle cerebral artery (MCA) flow velocity by transcranial Doppler technique. The cerebral perfusion pressure (CPP) was thus continuously recorded (CPP = BP - EDP). During steady-state CPB with constant hematocrit, temperature, and arterial carbon dioxide tension (PaCO2), MCA flow velocity varied with changing CPP in a pressure-passive manner, indicating that the cerebral autoregulation was not operative. During moderately hypothermic (28 to 32 degrees C), nonpulsatile CPB, with steady-state hematocrit, temperature, and pump flow, we deliberately and rapidly changed PaCO2 for periods of 1 or 2 minutes by increasing gas flow to the membrane oxygenator, thereby testing the cerebral CO2 reactivity. Nineteen CO2 reactivity tests, performed at CPP levels ranging from 17 to 75 mm Hg, disclosed that the cerebral CO2 reactivity decreased with CPP, especially with CPP levels below 35 mm Hg. In these patients, concomitant changes in CPP during the CO2 reactivity test could be compensated for by adjusting the observed change in MCA flow velocity. The corrected CO2 reactivity values obtained in this way ranged from below 1.0 (observed at CPP levels below 20 mm Hg) to a 3.0 to 4.5% X mm Hg-1 change in PaCO2 (observed at CPP levels above 35 mm Hg).(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Flow Velocity↗
PubMed1985

Digital subtraction angiography (DSA) in the evaluation of brain death. A comparison of conventional cerebral angiography with intravenous and intraarterial DSA.

Demonstration that intracranial circulation has ceased is the ultimate proof of brain death. This study was performed to evaluate digital subtraction angiography (DSA) compared with conventional cerebral angiography in the diagnosis of brain death. Intravenous as well as intraarterial DSA was found suitable in the diagnosis of arrested intracranial circulation.

Adolescent↗
PubMed1985

Pediatric head injuries caused by traffic accidents. A prospective study with 5-year follow-up.

In an unselected series of 488 patients with head injuries referred to a general surgical department, there were 126 children aged 0-19 years whose head injuries were a result of traffic accidents. In age group 0-4 years, only 23% of the head injuries were due to traffic accidents. In age groups 5-9, 10-14, and 15-19 years, however, traffic accidents were the main cause of the injuries, being responsible for 47%, 65% and 82% of the cases respectively. Both age groups 5-9 and 10-14 years had an unusually high proportion of bicycle injuries, while motorcycle and automobile accidents were the leading causes of injury in age group 15-19 years. Eight children (6%) died as a result of head trauma. Furthermore, among the survivors there were 8 children with severe head injuries (post-traumatic amnesia lasting 24 h), the rest being minor head injuries. All the survivors but one returned to school and achieved reasonable performances. Repeated follow-up studies at 3 months, 1 and 5 years, including interviews with the parents, disclosed that several of the children had headache, dizziness and other complaints. These subjective complaints subsided with time, but with different patterns, in the younger and older age groups. It is concluded that the "postconcussional syndrome" is not uncommon in children, but it may be better tolerated and resolves more completely with time than in adults. Eight children (7%) had one seizure or more during the 5-year follow-up period.

Accidents, Traffic↗
PubMed1985

Cerebral perfusion during nonpulsatile cardiopulmonary bypass.

The recording of middle cerebral artery (MCA) flow velocity by the transcranial Doppler method offers a new, noninvasive, continuous technique for studies of cerebral circulation. Comparative studies of electromagnetic internal carotid artery (ICA) flowmetry and MCA flow velocity by the transcranial Doppler technique have demonstrated that observed changes in MCA flow velocities reflect concomitant changes in cerebral circulation. Eleven high-risk patients undergoing cardiopulmonary bypass (CPB) procedures were included in a pilot study. Arterial blood pressure (BP), central venous pressure, and epidural intracranial pressure (EDP) were recorded during CPB. Cerebral electrical activity was recorded by a cerebral function monitor. Flow velocity in the MCA was increased during nonpulsatile CPB in 10 of the 11 patients. This increase was related to the degree of hemodilution, and the flow velocity during steady-state CPB was 80 to 300% of the prebypass value. The MCA flow velocity changed, however, in a pressure-passive manner with the cerebral perfusion pressure (CPP = BP - EDP) in the individual patient, which indicates that cerebral autoregulation was not operative. During the first 15 minutes after termination of bypass, the MCA flow velocity was reduced, but remained higher than the prebypass level, 110 to 210% of the level during the last 5 minutes preceding CPB.

Adult↗
PubMed1985

Dissociation between cerebral autoregulation and carbon dioxide reactivity during nonpulsatile cardiopulmonary bypass.

Five patients undergoing cardiopulmonary bypass (CPB) procedures were extensively monitored because of anticipated high risk for neurological complications. Arterial blood pressure (BP), central venous pressure, and epidural intracranial pressure (EDP) were continuously recorded throughout CPB; thus, information on the cerebral perfusion pressure (CPP) was also continuously available (CPP = BP - EDP). Cerebral electrical activity was recorded by a cerebral function monitor. The flow velocity in the middle cerebral artery (MCA) was recorded using a transcranial Doppler technique. During steady-state CPB (constant hematocrit, constant temperature, and constant flow from the heart-lung machine) partial pressure of arterial carbon dioxide (PaCO2) was repeatedly changed to study the effect of changes in this variable on MCA flow velocity during nonpulsatile bypass. During CPB with constant temperature, hematocrit, and PaCO2, the effect of changes in CPP on MCA flow velocity was recorded and analyzed. During nonpulsatile, moderately hypothermic (28 degrees to 32 degrees C), low-flow (1.5 L/min/m2) CPB, there was no evidence of cerebral autoregulation, with CPP levels ranging from 20 to 60 mm Hg. The CO2 reactivity, however, was clearly present and in the range of 1.9 to 4.1%/mm Hg, indicating that there was a dissociation between cerebral autoregulation and CO2 reactivity under these circumstances.

Aged↗
PubMed1985

Some observations on cerebral perfusion during cardiopulmonary bypass.

Blood flow was recorded with an electromagnetic flow probe on one internal carotid artery (ICA) during cardiopulmonary bypass (CPB) in 5 patients. The ICA flow was monitored continuously along with arterial blood pressure, epidural intracranial pressure, and cerebral electrical activity using a cerebral function monitor (3 patients). The ICA flow increased by 50 to 100% at the inception of extracorporeal circulation. This rapid enhancement of flow occurred within a thirty-second period and was due to rapid arterial hemodilution caused by introduction of the priming solution. A transitory fall in ICA flow was observed during subsequent minutes when the well-recognized drop in blood pressure took place and the cerebral perfusion pressure (CPP = blood pressure - epidural intracranial pressure) was reduced to less than 30 mm Hg. In only one instance, however, when CPP fell to 15 mm Hg, was the fall in flow lower than the prebypass level. Throughout the rest of CPB, with steady-state hemodilution and CPP levels in the range of 30 to 50 mm Hg, ICA flow was markedly enhanced (50 to 100% above the prebypass level). The flow pattern, however, disclosed a pressure-passive system, indicating that cerebral autoregulation was impaired or that the CPP levels were lower than the individual lower limit of cerebral autoregulation during the period of steady-state hemodilution on CPB. A transient depression of cerebral electrical activity was seen in 2 patients shortly after the introduction of CPB. This phenomenon is suggestive of qualitatively insufficient perfusion and was observed even when ICA bulk flow was increased (hematocrit values, 13 to 17%).

Adult↗
PubMed1983

The effect of thiopentone on somatosensory evoked responses and EEGs in comatose patients.

EEGs and somatosensory evoked responses from the brachial plexus, neck and scalp were recorded in seven comatose patients on continuous thiopentone infusion. Although pathological in five of the patients, the evoked responses were present in all. Additional amounts of thiopentone producing a full suppression of all spontaneous EEG activity had no effects either on the configuration of the evoked responses or on the central conduction times. This resistance of the somatosensory evoked responses to a deep and sustained thiopentone narcosis makes it a useful test in comatose patients receiving this treatment.

Adolescent↗
PubMed1983

Cerebral damage following open-heart surgery in deep hypothermia and circulatory arrest.

Six patients undergoing aortic arch replacement during deep hypothermia and circulatory arrest were subjected to studies including serial determinations of total creatine kinase (CK) activity in the cerebrospinal fluid (CSF), monitoring of the intracranial epidural pressure and the cerebral perfusion pressure and clinical neurological evaluation. In two of four patients with postoperative pressure monitoring, a marked increase in pressure was seen. In one case this pressure rise terminated in brain tamponade six days postoperatively, despite aggressive treatment with steroids, mannitol and barbiturate. In comparison with patients undergoing surgery for valve replacement or aorto-coronary by-pass, some of the patients with aortic arch replacement clearly sustained more severe cerebral damage, as judged by clinical examination and autopsy findings as well as by assessment of the degree or extent of the neuronal damage from CK activity in CSF. Patients of this type are obvious candidates for postoperative neuro-intensive monitoring and care. Repeated pulsed Doppler flow velocity determinations in precerebral arteries, performed bedside, combined with monitoring of the cerebral perfusion pressure, provide a useful indication of the cerebral circulatory state in such situations.

Adult↗
PubMed1983

Monitoring of intracranial pressure after open-heart surgery.

Brain damage following open-heart surgery is receiving increasing attention. Efforts are being made to improve the setting for cardiac surgery so as to avoid such complications. When they occur, their recognition is retrospective, when the cerebral lesion is inevitable. Because heavy sedation is necessary, clinical supervision with respect to brain function is both difficult and unreliable in the early postoperative period. We therefore submitted 34 selected patients to neurosurgical intensive care supervision. The measures included postoperative monitoring of intracranial epidural pressure (EDP), of arterial blood pressure (BP) and of central venous pressure (CVP). In 25 patients there was rise in EDP during the first postoperative hours. Six of these patients received mannitol treatment and in three of them barbiturate was additionally given, in order to reduce EDP and improve the cerebral perfusion pressure (CPP = BP-EDP). Nevertheless EDP progressed to brain tamponade six days postoperatively in one case. In patients with raised EDP, weaning from the ventilator should be postponed until EDP has almost normalized. The EDP recording is a valuable guide in the postoperative management of the individual patient.

Blood Pressure↗