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Biomedical subjects

K W Jacobi

Publications and source records attributed to K W Jacobi.

At least 55 records · Page 3Linked to original sources
PubMed1991

[Ocular circulatory changes in halothane-nitrous oxide intubation anesthesia with special reference to arterial CO2 partial pressure. I. Phenomenology of changes].

UNLABELLED: In 20 patients (5 with cataract, 15 with strabismus), general anesthesia was performed using halothane (inspiratory concentration: 0.5 vol.%) and nitrous oxide (65 vol.%); thiopental was employed for induction of anesthesia, vecuronium and succinylcholine were used for neuromuscular blockade prior to intubation. In series 1, the patients were slightly hyperventilated (PCO2 33 mmHg, on average). In series 2, the arterial PCO2 was changed in a range between 20 and 45 mmHg. By means of oculo-oscillo-dynamography, we determined the systolic retinal and ciliary perfusion pressures (PPs,ret and PPs,cil) as well as the respective ocular blood pressures (Ps,ret and Ps,cil), the ocular pulsation volume (PVoc) and the pulsatile ocular blood flow (Fp,oc = PVoc x heart rate). The intraocular pressure (Pio) was measured with the Draeger hand-applanation tonometer. Results of series 1: Measured 5 and 15 min after intubation, PPs,ret was reduced by averages of 12.5 and 20.2 mmHg, respectively, corresponding to decreases of 13.1 and 21.2% compared to the initial values. Ps,ret was decreased by 15.4 mmHg (14.2%) 5 min after intubation and by 27.1 mmHg (25.0%) 15 min after intubation. The ciliary pressures (PPs,cil and Ps,cil) were changed by similar amounts. PVoc was reduced by 0.3 microliters (50.8%) during both time periods after intubation. Fp,oc was lowered by 19.5 microliters/min (41.0%) and by 26.4 microliters/min (55.5%), measured 5 and 15 min after intubation, respectively. Pio was decreased by 1.6 mmHg (11.3%) and by 7.6 mmHg (53.5%), respectively. The systolic brachial artery pressure was reduced by 12.6 mmHg (9.5%) 5 min after intubation and by 29.1 mmHg (21.9%) 15 min after intubation. The diastolic branchial artery pressure showed a slight initial increase, followed by a small decrease. All changes were highly significant (P less than 0.001; 1-factor analysis of variance plus Scheffé test). Results of series 2: In a PCO2 range between 40 and 45 mmHg (normo-until slight hypoventilation; determined 5 min after intubation), PVoc and Fp,oc averaged 0.43 microliter and 42.9 microliters/min, respectively. In a PCO2 range between 30 and 35 mmHg (slight hyperventilation), PVoc and Fp,oc averaged 0.38 microliters and 36.1 microliters/min, respectively; and in a PCO2 range between 20 and 25 mmHg (forced hyperventilation), they averaged 0.21 microliter and 22.8 microliters/min, respectively. All other variables were not dependent on the PCO2 level. CONCLUSIONS: The lowering of PVoc and Fp,oc, observed during halothane-nitrous oxide anesthesia--especially with forced hyperventilation-, may be interpreted as reduced pulsatile choroidal blood flow.(ABSTRACT TRUNCATED AT 400 WORDS)

Aged↗
PubMed1991

[Changes in ocular circulation in halothane-nitrous oxide intubation anesthesia with special reference to the arterial CO2 partial pressure. II. Mechanisms of change].

UNLABELLED: In part I of this study [Hessemer and associates, Klin. Mbl. Augenheilk. 199 (1991) 346-355] the phenomenology of the ocular circulatory changes, found during general anesthesia using halothane and nitrous oxide, has been described. These changes are analyzed with respect to their mechanisms.-- RESULTS: There was a significantly (P less than 0.05) linear relation between the anesthesia-induced reduction of the systolic ocular (retinal and ciliary) blood pressures and the decrease of the systolic brachial artery pressure (delta Ps,bra). The same relation was present between the reduction of the systolic ocular (retinal and ciliary) perfusion pressures and delta Ps,bra. The correlation coefficients for the designated relations ranged between 0.37 and 0.58. The relation between the anesthesia-induced intraocular pressure reduction and delta Ps,bra was--in tendency--linear (P = 0.07), at least for the time period 5-15 min after intubation; the correlation coefficient amounted to 0.37. The reduction of both the ocular pulsation volume (PVoc) and the pulsatile ocular blood flow (Fp,oc) did not depend on the systemic blood pressure, but on the arterial CO2 tension (PCO2): Decreasing PCO2--i.e., increasing hyperventilation--was paralleled by decreases of PVoc and Fp,oc. The relations PVoc vs. PCO2 and Fp,oc vs. PCO2 were significantly linear (P less than 0.01), the correlation coefficients ranged between 0.58 and 0.7.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Endotracheal↗
PubMed1991

[Effect of hyaluronidase on ocular circulatory changes caused by retrobulbar anesthesia].

Twenty patients had retrobulbar anesthesia with 5 ml mepivacaine (Scandicain) without or with addition of 150 units of hyaluronidase (Kinetin). Before and 15 min after injection, we determined--by means of oculo-oscillo-dynamography--the systolic retinal and ciliary perfusion pressures, the respective ocular blood pressures (intramural pressures) and the ocular pulsation volume (PVoc) as well as the intraocular pressure (Pio; hand-applanation tonometer). Without hyaluronidase, the ocular perfusion and blood pressures were lowered by 11.8 and 3.9 mmHg, respectively, and PVoc was reduced by 0,40 microliters, whereas Pio was increased by 7.9 mmHg With hyaluronidase, the ocular perfusion and blood pressures were decreased by averages of 12.7 and 6.8 mmHg, respectively, PVoc was reduced by 0.42 microliters, and Pio was increased by 6.0 mmHg. Within each group, all changes were significant. There were, however, no significant differences between the two groups, i.e., the "spreading factor" hyaluronidase does not influence the inhibitory effects of retrobulbar anesthesia on ocular circulation.

Aged↗
PubMed1990

[Changes in the circulation of the eye caused by Vörösmarthy preoperative ocular pressure].

Prior to, directly after and 15 minutes after preoperative Vörösmarthy oculopression (30, 40, or 50 mm Hg; 15 min), 30 patients were examined by oculooscillodynamography after Ulrich. Systolic retinal and ciliary perfusion pressures were higher directly after oculopression, whereas the systolic and diastolic ocular blood pressures (intramural pressures) were lower. These changes did not depend significantly on the level of oculopression. Fifteen minutes after oculopression, the ocular perfusion and blood pressures were largely normalized. The hemodynamic changes observed reflect the decrease in intraocular pressure resulting from oculopression. The changes are thought to have a beneficial effect on ocular perfusion (reduction in tissue pressure, decrease in vascular resistance, increase in transmural pressure). The authors' results are consistent with the finding in animal experiments that blood flow to the retina, optic nerve, and uvea increases for a short time after oculopression (Jay et al., Acta Ophthalmol. 1986).

Aged↗
PubMed1990

[Diffractive multifocal intraocular lenses. A prospective clinical study].

Forty-three patients were examined three months after implantation of a multifocal or bifocal intraocular lens following cataract extraction. With far vision correction, simultaneous bifocal function with far acuity better than 0.5 and near acuity better than Nieden 3 was achieved in 95.4% of these cases. Glare sensitivity was tested with the BAT and mesopic visual acuity was examined with the Ocutrast. No statistical differences were found between these patients and a control group with monofocal IOLs.

Aged↗
PubMed1990

[Pre- and postoperative non-contact tonometry].

The AO II non-contact tonometer (NCT) was compared with the Goldmann applanation tonometer (GAT) in 50 patients preoperatively and on the first day after cataract surgery. After pooling the preoperative and postoperative values, the relationship between NCT (y axis) and GAT (x axis) was described by the following regression: y = 1.01x - 0.69, where 1.01 is the slope and -0.69 (in mm Hg) is the y intercept of the regression line. The standard deviation (SD) in relation to the regression line was 2.19 mm Hg (y values). After separating the preoperative (n = 100; pressure range 6-21 mm Hg) and postoperative values (n = 47; pressure range 6-30 mm Hg) the following equations were obtained: preoperatively: y = 0.89x + 0.82 (SD 2.2 mm Hg); postoperatively: y = 1.06x - 1.15 (SD 2.24 mm Hg). Since the postoperative regression line comes close to that required for legal verification, the NCT may - with limitations - also be recommended for measuring IOP after cataract surgery. Both preoperatively and postoperatively, a significantly linear relationship was found between corneal thickness and the difference GAT minus NCT readings. This implies that in normal eyes with thin corneas the NCT tends to underestimate IOP, while in eyes with thick corneas there is a tendency to overestimate IOP. Even slight corneal edema (postoperatively) reduces this effect.

Cataract Extraction↗
PubMed1990

[Ocular circulatory changes caused by retrobulbar anesthesia with and without added adrenaline].

UNLABELLED: In 80 patients, retrobulbar anesthesia (RBA; 5 ml of a lidocaine-bupivacaine mixture with hyaluronidase) with or without addition of adrenaline (after-mixing concentration 1:500,000) was performed preoperatively. In 2 examination series, the acute and medium-term effects of RBA on the following ocular circulatory variables were investigated: ocular pulsation volume (PVoc), systolic ciliary and retinal perfusion pressures or blood pressures, respectively (method: oculo-oscillo-dynamography). RESULTS: RBA with adrenaline: Directly after injection, PVoc was reduced by an average of 49%, the ocular perfusion and blood pressures were lowered by averages of 8.0 and 4.3 mmHg, respectively, and the intraocular pressure (Pio; hand-applanation tonometer) was elevated by 3.5 mmHg. 15 min after injection, PVoc and the ocular perfusion and blood pressures were even slightly more reduced, whereas Pio had reassumed its pre-injection level. RBA without adrenaline: During both time periods after injection, the reduction of PVoc averaged 10% less compared to RBA with adrenaline. The changes in ocular perfusion and blood pressures and in Pio, however, were not significantly different from RBA with adrenaline. CONCLUSIONS: The lowering of PVoc--which variable is determined mainly by the pulsatile choroidal blood flow--in concert with the lowered ciliary perfusion and blood pressures is indicative of a reduced ciliary blood flow during RBA. Because of the decreased retinal perfusion and blood pressures, there is also a higher risk of reduced blood supply to the retina. Only to some degree, the observed inhibitory RBA effects on ocular circulation can be explained by adrenaline, and to an even smaller degree by the only transient Pio elevation.

Adult↗
PubMed1990

[Plasma level of lidocaine and adrenaline in local anesthesia with addition of colloid in eye surgery].

This study was undertaken to investigate the plasma levels of lidocaine and adrenaline after local anaesthesia for ophthalmic surgery and the influence of addition of hydroxyethyl starch (HES) on the resorption of the local anaesthetic solution. Prior to cataract surgery, two groups (each consisting of 10 patients) received a retrobulbar block (5 ml) and a facial nerve block (5 ml; O'Brien technique) with lidocaine 2% and adrenaline 1:80000, with or without addition of 10% HES 200/0.5 (relation 1:1) in equal volumes and concentrations. The plasma levels of lidocaine and adrenaline were measured by high-pressure liquid chromatography. In both groups, the individual peak concentrations of lidocaine (8.62 micrograms/ml) and adrenaline (7.514 pg/ml) reached the toxic range. There was no evidence of intravascular injection, and no severe cardiovascular reactions were observed. In 9 patients, resorption was slow and led to low peak concentrations. A rapid resorption with high peak concentrations was found in 11 patients. Peak levels of lidocaine were reached after 15 min and those of adrenaline after 3-5 min. Plasma levels of lidocaine and adrenaline were not significantly influenced by the addition of HES, although the highest peak concentrations were found in the group without the addition of HES.

Aged↗
PubMed1990

[Special intra-ocular lenses].

Intraocular lens (IOL) implantation is the method established worldwide for visual rehabilitation following cataract surgery. IOL's with particular characteristics and/or for special purposes are available for clinical or experimental use. Bifocal and multifocal IOLs have two or more foci for simultaneous far and near vision. The first clinical results are promising. The theoretically expected disadvantages, i.e., reduced contrast sensitivity or reduced visual acuity under reduced contrast conditions, have not yet been found in clinical studies. In cases of age-related macular degeneration, IOLs with a high negative diopter power in the center can be implanted as part of a Galilei telescope. By using high-plus power spectacles, a 2.5x to 4x magnification and a wide field of view can be achieved. Clinical investigation has started recently. Intraocular lenses for the correction of high-grade myopia are being tested by some surgeons. These lenses are made to be implanted in phakic eyes with a clear crystalline lens. Angle-supported and iris-fixated types are under investigation. Longterm results will show the clinical efficacy and safety. Other special intraocular lenses are iris-color lenses and a polymethymethacrylate (PMMA) iris diaphragm.

Humans↗
PubMed1990

[Modification of hemodynamic retrobulbar anesthesia effects by different oculopression procedures (with and without orbital compression)].

For studying the influence of orbital compression--an essential component of the clinically used methods of oculopression--on the hemodynamic effects of retrobulbar anesthesia, two series of investigations were performed preoperatively in 40 patients. In series 1, we initially performed retrobulbar anesthesia (RBA) with 5 ml of a bupivacaine/lidocaine mixture with adrenaline. RBA was followed by a 15-min period of suction-cup oculopression (SCO; negative pressure -100 and -150 mmHg in 10 patients each), which represents an experimental "pure" oculopression without compression of orbital tissue. In series 2, RBA was followed by a 15-min period of Vörösmarthy oculopression (VMO; pressure 30 and 40 mmHg in 10 patients each) which produces both ocular and orbital compression. Before and again after both RBA and oculopression, we determined the intraocular pressure (pio), the systolic retinal and ciliary perfusion pressures or blood pressures, respectively, and the ocular pulsation volume (PVoc) using oculo-oscillo-dynamography. After injection, pio was increased by an average of 4.5 mmHg, the ocular perfusion and blood pressures were lowered by 8.5 and 4.2 mmHg, respectively, and PVoc was reduced by an average of 0.47 microliters (51%) in both series 1 and 2. These effects of RBA may be interpreted as a depressing influence on ocular circulation. After SCO, pio was lowered by an average of 8.5 mmHg, and the ocular blood pressures remained unchanged at the post-injection levels. The perfusion pressures, however, were increased to their initial values, and even beyond in some cases. Thus, the inhibitory effects of RBA on ocular circulation are partially set off by the effects of SCO.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Tono-Pen, a new tonometer.

UNLABELLED: The Tono-Pen is a miniaturized Mackay-Marg tonometer with electronic signal analysis and digital pressure display. In study 1, we compared the Tono-Pen with Goldmann tonometry in 108 healthy human subjects (216 eyes). In 33 of these subjects, the IOP was changed in a range between 0 and 50 mmHg by a scleral suction-cup system. In study 2, the Tono-Pen was compared with a Statham membrane manometer in 6 humans (12 eyes), 3-6h after death. The IOP was changed in a range between 0 and 60 mmHg by an infusion system. - RESULTS: Related to the Goldmann tonometer, the Tono-Pen gave a small overestimation of IOP below 16 mmHg (maximum deviation 1.5 mmHg at 0 mmHg Goldmann reading). Above 16 mmHg, however, the Tono-Pen increasingly underestimated the IOP determined by Goldmann tonometry (maximum deviation 8 mmHg at 50 mmHg Goldmann reading). Related to the manometer, the Tono-Pen gave a small overestimation of IOP below 17 mmHg and small underestimation above 17 mmHg (maximum deviation 2.5 mmHg at manometer readings of 0 and 60 mmHg, respectively). - CONCLUSIONS: Throughout the entire clinically relevant IOP range, an acceptable relationship between Tono-Pen and manometer readings was found in human cadaver eyes, whereas the relationship between Tono-Pen and Goldmann tonometric readings in the clinical study was found to be acceptable only in the low and physiological IOP range. The considerable deviation from the Goldmann readings in the high IOP range requires further modifications of the Tono-Pen.

Adolescent↗
PubMed1989

[Preoperative use of suction cup oculopression in comparison with Vörösmarthy oculopression].

In contrast to Vörösmarthy oculopression (VOP), suction-cup oculopression (SOP) is "pure" oculopression without compression of orbital tissue. Prior to 44 cataract operations with posterior chamber lens implantation, the authors performed SOP (negative pressure - 110 mm Hg) or VOP (level of oculopression 30 mm Hg) of the same duration (average 26 min). Before oculopression, a retrobulbar injection (RBI) was performed for local anesthesia. The intraocular pressure (IOP) was decreased by 14 mm Hg to 3.9 and 4.9 mm Hg after SOP and VOP, respectively. After VOP, the iris-vitreous diaphragm was more frequently judged to be concave, i.e., vaulted against the retina, than after SOP (standardized questionnaire). After RBI + SOP, a post-injection of anesthetic was necessary in three cases; no additional injection was required after RBI + VOP. In conclusion, identical preoperative reductions in IOP can be achieved with SOP and VOP. Regarding the form of the iris-vitreous diaphragm and the frequency of post-injection, the differences between the two methods may be related to the lack of orbital compression during SOP.

Aged↗
PubMed1989

[Tono-pen versus manometer. Comparative measurements of intraocular pressure in human cadaver eyes].

A new hand-held tonometer, the Tono-Pen (TP), was compared with a Statham membrane manometer (MAN). The TP is a pen-sized Mackay-Marg tonometer with electronic signal analysis and digital pressure display. Comparative measurements of intra-ocular pressure (IOP) were performed on six cadavers (12 eyes in situ), 3-6 hours after death. The IOP was changed in 5 to 10 mm Hg steps in a range between 0 and 60 mm Hg by an infusion system. As compared to the manometrically determined IOP, the TP gave small overestimation of IOP below 17 mm Hg and a small underestimation above 17 mm Hg (maximum deviation 2.5 mm Hg). The mean values of 29.9 (TP) and 30.4 mm Hg (MAN) were not significantly different (p greater than 0.05, analysis of variance). The correlation coefficient was 0.99. The relationship between TP (y axis) and MAN (x axis) pressure readings is characterized exactly by a slightly curvilinear graph (y = 0.82x + 0.0002x2 + 2.52; mm Hg). This may be approximated by a regression line with a slope of 0.94, a y intercept of 1.46 mm Hg and a standard deviation of the TP readings in relation to the regression line of 2.36 mm Hg. In conclusion, the good agreement between TP and MAN pressure readings is superior to the recently described agreement between TP and Goldmann tonometer readings.

Electronics↗
PubMed1989

[Detection of cystoid macular edema with orally administered fluorescein].

To detect cystoid macular edema after extracapsular cataract extraction, the authors used indirect ophthalmoscopy after oral application of fluorescein, rather than intravenous fluorescein angiography. The patients drank 10-20 ml 10% fluorescein sodium in 250 ml orange juice. Ophthalmoscopy was performed 30-45 minutes later using an exciter filter. Twenty-five patients with a tentative clinical diagnosis of cystoid macular edema were examined in this way. In six of them a manifest edema was detected. The results were confirmed by intravenous fluorescein angiography.

Administration, Oral↗
PubMed1989

[Absorption and fluorescence spectrometry measurement of intraocular lenses].

Light absorption and fluorescence measurements can be used to detect accumulations of small molecules in intraocular lenses (IOLs). It was shown that HEMA IOLs can store and to some extent release a variety of drugs and fluorescein. PMMA and silicone IOLs, however, do not have this characteristic. UV-blocking IOLs absorb UV light completely. The absorption limit varies between 390 and 410 nm, depending on the make. Neither absorption nor fluorescence response were affected by exposure to UV light or heat.

Acebutolol↗
PubMed1989

[Changes in uveal and retinal hemodynamics caused by retrobulbar anesthesia using various injection volumes].

In 20 patients, retrobulbar injections of 2 or 5 ml local anesthetic (bupivacaine-lidocaine mixture with hyaluronidase) were given preoperatively. Directly after the 5-ml injection, the systolic retinal and ciliary perfusion pressures (measured by means of oculo-oscillo-dynamography according to Ulrich) were reduced by an average of 5.6 mmHg (p less than 0.001) in comparison with the untreated fellow eyes. The ocular pulsation volume (PVoc) was reduced by 39%. Fifteen minutes after the 5-ml injection, the perfusion pressures and PVoc were reduced even slightly more. The intraocular pressure (Pio) was increased by an average of 3.2 mmHg directly after the 5-ml injection, whereas after 15 min the Pio had reassumed its preinjection level. After the 2-ml injection, the PVoc was reduced by the same amount as found after the 5-ml injection. However, there was no significant change in perfusion pressures or Pio after the 2-ml injection. The findings observed during retrobulbar anesthesia may be interpreted as an inhibitory effect on ocular hemodynamics, which increases at higher injection volumes. This effect cannot be accounted for by adrenaline--which was not employed--and can at best only partially be accounted for by the changes in Pio.

Aged↗
PubMed1989

[Intraocular pressure and ocular hemodynamics following oculopression with and without added retrobulbar anesthesia].

Two series of experiments were performed prior to cataract surgery. In series 1, in 30 patients oculopression was performed for 15 min (30, 40 or 50 mmHg). Directly after oculopression the intraocular pressure (Pio) was found to be reduced by an average of 10.7 mmHg. Systolic retinal and ciliary perfusion pressures (measured by means of oculo-oscillodynamography according to Ulrich) were found to be increased by an average of 5.4 mmHg, and the ocular pulsation volume (PVoc) was unchanged. In series 2, we injected 5 ml of anesthetic plus adrenaline behind the eye in 20 patients, followed by 15 min of oculopression (30 or 40 mmHg). Directly after the injection, Pio was found to have increased by 3.7 mmHg, and the perfusion pressures and PVoc were reduced by an average of 8 mmHg and 51%, respectively. Directly after oculopression (15 min after injection), Pio was lower by 10.1 mmHg, but the perfusion pressures and PVoc also remained lower. The changes observed in series 1 and 2 did not depend on the amount of oculopression. We conclude that a reduction in Pio after oculopression has a beneficial effect on the ocular circulation (increased perfusion pressures), whereas retrobulbar anesthesia has an inhibitory effect (reduction of perfusion pressures and PVoc). The hemodynamic effects of oculopression are largely suppressed by additional retrobulbar anesthesia.

Aged↗