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Biomedical subjects

L E Linder

Publications and source records attributed to L E Linder.

At least 55 records · Page 3Linked to original sources
PubMed1985

"Half-way" venous catheters. II. Anatomoradiological basis.

In order to develop a "half-way" venous catheter for clinical use, anthropometric (n = 200), radiographic (n = 101), and phlebographic (n = 44) investigations were undertaken to determine the lengths, diameters, and morphology of the basilic and cephalic veins from fossa cubiti to the lateral edge of the first rib. The lengths of basilic and cephalic veins varied from 25 to 45 cm, exceeding 40 cm in approximately 5% of cases. Catheter lengths to be inserted were correlated ("r" = 0.6-0.7) with body heights, accurately estimated by 1/5 of the body height (cm) plus 2 cm for the basilic vein, and 4 cm for the cephalic vein. The cephalic veins have small proximal end diameters (mean = 6 mm), and present terminal arches of 2-3 cm. These are connected by a rich anastomotic network to the superficial cervical veins. The basilico-axillary courses are regular with gradually increasing diameters (mean = 16 mm), but in some observations, with the arms maximally abducted, the axillary veins presented accentuated folds. With these considerations, we recommend the insertion of the "half-way" catheters by basilic approach with the patient's arm in 90 degree abduction. The axillosubclavian length (mean = 18.5 cm) ensures wide limits for accurate placement of the "half-way" catheter tips when a basilic approach is used. Further, their large diameters (16-19 mm) make flotation of the soft catheters probable.

Adolescent↗
PubMed1985

"Half-way" venous catheters. III. Tip displacements with movements of the upper extremity.

Directions and sizes of displacement of "half-way" catheter tips with movements of the upper extremities were investigated in thoracic radiographs in 21 patients (10 women and 11 men), 28-88 years old. Ten catheters were inserted by basilic, and 11 by cephalic veins punctured at the fossa cubiti. Catheter tip positions were related to the lateral edge of the first rib. The tip position with the patient's arm in 90 degree abduction was considered as the reference point. Displacements caused by maximal flexion of the forearm, maximal adduction of the upper extremity, and maximal elevation of the brachium plus maximal flexion of the forearm were studied. With all movements and venous approaches there were significantly more medial than lateral displacements (P less than 0.001). The medial displacements varied from 0.2-5.0 cm, and the lateral ones from 0.5-1.8 cm. Location of the "half-way" catheter tips in the proximal axillary vein, at the lateral edge of the first rib, is recommended. As found previously, this may be obtained by inserting a catheter length representing 1/5 of the patient's height. Such a location inhibits harbouring of the "half-way" catheter tips in the jugular veins with movement in the upper extremities. Furthermore, estimation of central venous pressures by axillary venous pressures is not affected.

Adult↗
PubMed1985

"Half-way" venous catheters. IV. Clinical experience and thrombogenicity.

"Half-way", Secalon-Seldy, soft venous catheters, 40 cm long, were inserted by basilic (n = 90) and cephalic (n = 31) veins at the fossa cubiti in 121 patients (71 men and 50 women) aged between 19 and 88 years whose heights varied from 152-197 cm. The inserted catheter lengths approximated 1/5 of the patient's height. Sixty-five per cent of 106 radiologically investigated catheter tips were located proximally in the axillary veins, and 34% distally in the subclavian veins. The duration of catheterization varied from 1 to 44 (mean 9 +/- 7) days (means +/- 1 s.d.). Perfect function was recorded in 93 of 121 catheters. No serious, but some minor complications were registered such as temporary interruption of infusion flow with movements of the arm (n = 12), partial or total catheter occlusion (n = 16), leakage of the infusate at the insertion site (n = 1), and pain along the vein during infusion (n = 2). Five patients (4%) developed thrombophlebitis 2-.10 days after insertion. Pull out phlebographies at catheter withdrawal (4-35 days after insertion) were performed in 36 patients. Radiological thrombi were small and similar to those recorded in another 53 phlebographies of "long-way" brachial catheters of similar stiffness. Neither local infection nor episodes of sepsis were registered over a period of 1,081 catheter days. "Half-way" catheters proved able to take over all the functions of both peripheral and central venous catheters, lacking the frequent complications (phlebitis and infection) of the former, and the serious mechanical complications (pneumothorax, vein perforations, and injuries of the ductus thoracicus, nerves, arteries, and heart) of the latter.

Adult↗
PubMed1984

Reduction of brain specific gravity in mice prenatally exposed to trichloroethylene.

The specific gravity of the brain is low at birth and increases in parallel with myelination and maturation. The brain specific gravity of litters from mice exposed to trichloroethylene (TCE) before and after mating was significantly lower than in litters from unexposed parents at birth as well as at the age of 10 and 20-22 days. This might indicate a delayed maturation. No significant difference between exposed and unexposed litters was observed at the age of one month.

Age Factors↗
PubMed1984

Material thrombogenicity in central venous catheterization III. A comparison between soft polyvinylchloride and soft polyurethane elastomer, long, antebrachial catheters.

Soft venous catheters, 36 made of polyurethane (PU) and 37 made of polyvinylchloride (PVC), were inserted in 73 patients via basilic and cephalic veins punctured at the cubital fossa, and compared regarding their thrombogenicity. The mean duration of catheterization was 12.5 days. Two patients with PU- and six patients with PVC-catheters developed clinical thrombophlebitis 4-36 days after insertion. The radiological thrombi were rather small with both PU- and PVC-catheters in both peripheral and central veins with no significant difference between the catheters. Also, the incidence of thrombosis and the rate of catheter occlusions were similar. The surface topography of the PVC-catheters was relatively smoother, but less uniform than that of the PU-catheters. Platelet adhesion in vitro to the catheter surfaces, expressed as ATP-concentration in relation to catheter area after contact with human blood, was relatively low with both catheters. The results suggest that soft PU- and PVC-catheters have a similar thrombogenicity.

Adolescent↗
PubMed1984

Dynamics of thrombophlebitis in central venous catheterization via basilic and cephalic veins.

The incidence distribution of thrombophlebitis after central catheterization via basilic and cephalic veins was investigated, using 227 catheters made of various plain or heparin-coated materials and with differing stiffness and surface structures. The platelet-adhesion stimulating properties were measured in vitro. Thrombophlebitis showed similar incidence patterns with all catheter types. The maximum incidence of venous reaction was found one to ten days after catheter insertion (central tendency 3-8 days with a peak at 5 days). After ten days the risk of thrombophlebitis fell significantly. The results supported the view that central venous catheters inserted via basilic or cephalic veins should not be withdrawn or exchanged as prophylaxis against thrombophlebitis, at any rate when long-term catheterization is intended. For conclusive comparisons between catheter materials regarding induction of clinically apparent thrombophlebitis, all the patients in the trial should be catheterized for ten days or more, unless symptoms of venous reaction arise earlier.

Adolescent↗
PubMed1983

Stiffness of central venous catheters.

Catheter stiffness has been suggested to be a principal factor in the thrombogenesis encountered after central venous cannulation. However, no data have been published to date about the stiffness of central venous catheters. A method for measuring catheter stiffness has been developed. The force needed to deflect a catheter tip 1.2 mm from a fastening point was measured with the help of a cantilever beam (Grass Model DA-7). Six different sections of each catheter were measured, and the final results expressed as an average of these. Twenty-seven central venous catheters made of silicone elastomer, polyurethane, polyvinylchloride, polyethylene and teflon were tested. The bending stiffness, EI (E = elastic modulus of the material, I = moment of inertia of catheter (a geometrical property)) was below 16 X 10(-6) Nm2 for all catheters made of silicone elastomer, polyvinylchloride and polyurethane. Polyethylene catheters were stiffer, but could be made softer by reduction of their diameters. Teflon catheters were up to 10 times stiffer than the catheters in the soft group. Heparinization and radioopacity of catheters do not significantly alter their bending stiffness. In a concomitant study the results indicate that there is a significantly lower incidence of thrombus formation in catheters with a bending stiffness below 16 X 10(-6) Nm2.

Catheterization↗
PubMed1983

Material thrombogenicity in central venous catheterization II. A comparison between plain silicone elastomer, and plain polyethylene, long, antebrachial catheters.

Central venous catheters of two types were inserted through basilic or cephalic veins punctured at the fossa cubiti in 61 patients: 39 soft silicone elastomer (S.E.) and 22 stiffer polyethylene (P.E.) catheters were compared regarding their thrombogenicity. Mean duration of catheterization was 6.5 days. Radiological thrombi in the peripheral and central veins visualized by phlebography were significantly smaller, and the incidence of the mural thrombi in the central veins significantly lower with the S.E. than with the P.E.-catheters, but the use of S.E.-catheters did not reduce the incidence of clinical thrombophlebitis in arm veins: 14 cases in the group with S.E. and four in that with P.E.-catheters. In both groups, the maximum incidence of clinical thrombophlebitis occurred 4-8 days after catheterization. Later, there seems to be a low risk for the appearance of clinical thrombophlebitis with both catheters. Neither the surface topography of the catheter materials, nor the platelet adhesion on their surfaces in contact with human blood in vitro offered conclusive arguments for interpretation of their thrombogenicity in vivo. Catheter stiffness seems to play an important role in inducing mural thrombus formation in central venous cannulation in man.

Adolescent↗
PubMed1982

Material thrombogenicity in central venous catheterization. I. A comparison between uncoated and heparin-coated, long antebrachial, polyethylene catheters.

In order to evaluate a new method of heparinization, uncoated (22) and heparin-coated (27) central venous polyethylene catheters were inserted in 49 patients via basilic and cephalic veins punctured at the fossa cubiti. The means duration of catheterization was 5.7 (1-11) days. One-third of the patients with heparin-coated catheters, and one sixth with uncoated catheters developed clinical thrombophlebitis, with a maximum incidence between 4 and 8 days after catheterization. A higher risk of developing thrombophlebitis in the first 4 days after catheterization was found in the patients with heparin-coated polyethylene catheters. After 8 days of catheterization, it seems that there is a lower risk of new cases of thrombophlebitis appearing both in patients with uncoated and those with heparin-coated polyethylene catheters. Radiological thrombosis, regardless of duration of catheterization and heparin-coating, was demonstrated in all 22 patients investigated by "pull-out" phlebography. The heparin-coating did not decrease the rate of thrombotic complications. Location of the catheter tip in subclavian veins was associated with a significantly higher incidence of large, parietal thrombi and catheter occlusion than when the tip was situated in anonymous veins, the superior vena cava, or the right atrium. Cannulation by heparin-coated, polyethylene tubing did not reduce the rate of catheter occlusion.

Adolescent↗
PubMed1982

Specific gravity of brain tissue during maturation.

The water content of the brain is closely related to the maturation and degree of myelination. In control rats studied from the day of birth to the age of 26 days, brain specific gravity increased in parallel to the decrease in water content (r = 1.00). Rats treated with 6-hydroxydopamine (6-OHDA) 100 microns/g daily during the first 2 or 4 days of life had significantly lower specific gravity than controls in all parts of the brain at the age of 2 weeks. With the smaller dose 6-OHDA, the specific gravity at the age of 1 month was lower than in controls in the occipital cortex; with the larger dose it was significantly reduced in all cortical regions as well as in the pons and the diencephalon. 2-months old 6-OHDA treated rats did not differ from controls. Rats pretreated with desipramine 30 min before administration of 6-OHDA to prevent uptake of 6-OHDA into catecholaminergic neurons did not differ from controls. Neonatal 6-OHDA treatment affects predominantly noradrenergic terminals in the cerebral cortex with cell bodies in the locus coeruleus. The present results are consistent with the hypothesis that these neurons have a trophic influence on the brain development during the postnatal maturation.

Aging↗
PubMed1981

Hypertension and brain oedema: an experimental study on acute and chronic hypertension in the rat.

To determine under what circumstances hypertension is associated with brain oedema, the specific gravity of the brain was measured in acutely hypertensive, renal hypertensive and spontaneously hypertensive rats. Maximum mean arterial pressure (MAP) in acute hypertension induced by intravenous amphetamine or bicuculline was 171 +/- 5 and 181 +/- 5 mmHg respectively. In spite of pronounced extravasation of Evans blue-albumin, there was no decrease in specific gravity except in the diencephalon in rats given bicuculline (p less than 0.05). Cortical and cerebellar samples from renal hypertensive rats (MAP 174 +/- 14 mmHg) were lighter than corresponding regions in normotensive rats (p less than 0.001) although the brains showed little or no macroscopic extravasation of Evans blue-albumin. Neither macroscopic protein leakage nor increase in water content was observed in brains from spontaneously hypertensive rats (MAP 210 +/- 5 mmHg). It is concluded that renal hypertension is more likely to lead to brain oedema than spontaneous genetic hypertension or acute hypertension.

Albumins↗
PubMed1980

Displacement of catheters inserted through internal jugular veins with neck flexion and extension. A preliminary study.

Displacement of central venous catheters inserted through internal jugular veins in adult man was estimated on chest x-rays in six patients and measured in six corpses. The downward displacement of the catheter tips with maximum neck flexion varied between 1.0 and 2.0 cm in patients, and between 1.0 and 2.5 cm in corpses. The upward displacement with maximum neck extension varied between 0.5 to 1.0 cm in patients and 0.5 to 1.5 cm in corpses. The total displacement varied between 1.5 to 3.0 cm in patients, and 1.5 to 4.0 cm in corpses. The geater displacement in corpses might be explained by detachment of sternocleidomastoid muscles, and by resection of the sternum and anterior ribs, performed for access to the heart and superior vena cava. There was no apparent correlation between the side and site of the vein puncture, body length, sternocleidomastoid length, distances from the punction sites to suprasternal notch, and values of the displacements of the catheter tips in any group. To avoid rhythm disturbances and perforation of the heart (possible complications of the catheter displacement), the necessity of locating central venous catheter tips 3.0 to 4.0 cm above the superior vena cava-right atrial junction, and firm fixation of the catheter is stressed.

Adult↗
PubMed1980

Do nitrous oxide and lidocaine modify the blood-brain barrier in acute hypertension in the rat?

Acute hypertension was induced by adrenaline or bicuculline in rats mechanically ventilated with 70% nitrous oxide in oxygen, in unrestrained rats breathing the same gas mixture, and in conscious unrestrained rats breathing air. The unrestrained rats had permanent indwelling catheters in the aorta and in one jugular vein. Three minutes after the pressure rise the rats were killed and the brains perfused in situ with saline. The protein leakage into the brain was studied with Evans blue-albumin and 125IHSA (human serum albumin). The extravasation of 125IHSA in unrestrained rats breathing nitrous oxide was higher than in rats breathing air after injection of bicuculline, but the difference was not statistically significant. Lidocaine significantly decreased the protein leakage in both conscious and anaesthetized rats. It is concluded that not only the vascular tone but also endothelial cell membrane properties can influence the hypertensive blood-brain barrier dysfunction.

Animals↗
PubMed1980

The blood brain barrier in renal hypertensive rats.

Spontaneous hypertensive rats (SHR) are less prone to develop a dysfunction of the blood-brain barrier (BBB) when exposed to an abrupt increase in blood pressure than normotensive rats (NR), probably as a result of vessel wall hypertrophy and increased vessel wall to lumen ratio. Hemodynamic studies have indicated that structural adaptation develops early as a response to the increased pressure load in renal hypertensive rats (RHR). In the present study RHR (one renal artery constricted and the contralateral kidney intact) were subjected to acute hypertension induced by bicuculline, a drug that induces an abrupt increase in blood pressure concomitant with pronounced cerebral vasodilatation. Protein leakage in the brain, as indicated by Evans blue-albumin and 125IHSA (human serum albumin) extravasation, was not reduced in RHR compared to NR. The cerebrovascular permeability was slightly but significantly (p < 0.01) increased in RHR even in the absence of further blood pressure manipulation. No neurological symptoms were observed in conscious RHR when the BBB dysfunction was aggravated by hypercapnia. The increased cerebrovascular permeability in RHR cold be due to a lower degree of structural adaptation in RHR compared to SHR and/or to some permeability-increasing humoral factor in renal hypertension.

Angiotensinogen↗
PubMed1978

Cerebrovascular permeability to protein in the rat during nitrous oxide anaesthesia at various blood pressure levels.

Rats anaesthetized with 70% nitrous oxide in oxygen have a high mean arterial pressure (MAP), usually in the range of 130-155 mmHg. It occasionally reaches higher levels, and when MAP exceeds 160 mmHg the cerebrovascular permeability may increase. In the present study all rats with MAP greater than 170 mmHg showed areas of protein leakage in the brain. When dealing with substances that normally do not pass the blood-brain barrier (BBB), this permeability increase may have important consequences. It is suggested that rats under nitrous oxide anaesthesia with MAP greater than 160 mmHg should not be included in studies in which an intact BBB is essential.

Animals↗
PubMed1978

Hypertension-induced protein leakage in the brain in ethanol-intoxicated conscious and anesthetized rats.

Ethanol has been shown to aggravate the blood-brain barrier (BBB) dysfunction in cerebral trauma and in cerebral gas embolism, possibly by changing the endothelial cell membrane. No difference in protein extravasation was found between intoxicated and control rats under nitrous oxide anesthesia after the injection of bicuculline, a drug that hemodynamically gives rise to high blood pressure in combination with cerebral vasodilatation. In contrast there was a statistically significant increase in protein leakage in conscious intoxicated rats. The fact that ethanol increased the vulnerability only in conscious rats might indicate that nitrous oxide and ethanol have a common effect on the endothelial cell membranes or that nitrous oxide neutralizes an action of ethanol. Protein leakage induced by acute hypertension is more severe in rats anesthetized with nitrous oxide than in conscious rats, a difference that might to some extent be related to an effect of nitrous oxide on the endothelial cells. Further studies are needed to evaluate the influence of ethanol and nitrous oxide on the endothelial cell membrane.

Alcoholic Intoxication↗