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Biomedical subjects

W Koller

Publications and source records attributed to W Koller.

At least 91 records · Page 5Linked to original sources
PubMed1989

[Biphasic positive airway pressure (BIPAP)--a new form of augmented ventilation].

Two modes of combining spontaneous breathing and mechanical ventilation are already in use: periodic mechanical support always followed by a period of spontaneous breathing (intermittent mandatory ventilation; IMV) and mechanical support of each spontaneous breath (inspiratory assistance; IA). Biphasic positive airway pressure (BIPAP), in contrast, is based on neither of the above mentioned principles. It is rather a mixture of pressure controlled (PC) ventilation and spontaneous breathing, which is unrestricted in each phase of the respiratory cycle. The BIPAP circuit switches between a high (Phi) and a low (Plo) airway pressure level in an adjustable time sequence. At both pressure levels the patient can breathe spontaneously in a continuous positive airway pressure system (CPAP). The volume displacement caused by the difference between Phi and Plo and the BIPAP frequency (F) contribute the mechanical ventilation to total ventilation. Duration of the Phi and the Plo phases can be independently adjusted. Similar to the I:E ratio during controlled ventilation, the phase time ratio (PhTR) is calculated as the ratio between the durations of the two pressure phases. A PhTR greater than 1:1 is called IR-BIPAP. A BIPAP system can be set up either as a continuous flow system, or as a demand valve system. A continuous-flow BIPAP system consists of a high-flow CPAP system, a reservoir bag, and a pneumatically controlled membrane valve in the expiratory limb. A magnetic valve operated by an impulse generator switches between Phi and Plo, controlling the pop-off pressures of the expiratory valve.(ABSTRACT TRUNCATED AT 250 WORDS)

Humans↗
PubMed1988

Lack of association between essential tremor and Parkinson's disease.

Four aspects of a possible association between essential tremor (ET) and Parkinson's disease (PD) were investigated: (1) the frequency of extrapyramidal signs in ET; (2) the frequency of concurrent ET and PD (i.e., monosymptomatic postural tremor for 5 or more years prior to onset of PD); (3) the frequency of ET in the families of PD patients; and (4) the frequency of PD in families of ET patients. Two hundred and thirty-seven ET patients (137 in London and 100 in Chicago) were evaluated. One hundred patients with PD and 100 normal control subjects were also investigated. Mild extrapyramidal signs occurred in only 4.5% of ET patients and were consistent with those found in normal aging. Only 3% of PD patients gave a history of uncomplicated ET. There was no difference in the frequency of a family history of PD between ET patients, a group of PD patients, and control subjects. Frequency of a family history of ET was higher among PD patients than control subjects, although the difference was not statistically significant. These data indicate that there is no association or genetic link between ET and PD.

Adolescent↗
PubMed1988

Effect of chlorhexidine-containing detergent, non-medicated soap or isopropanol and the influence of neutralizer on bacterial pathogenicity.

In handwashing experiments with Salmonella typhimurium the effect of chlorhexidine (CHX) on the pathogenicity of surviving bacteria was assessed with and without a neutralizer in a mouse model of infection. Without neutralizer the LD50 of CHX handwash fluids was raised. Neutralizer in suspensions of untreated bacteria caused a reduction of LD50 up to 1.2 logs. Thus, in contrast to soap or alcohol, CHX without neutralizer exerted a slight 'depathogenizing' action and neutralizer a slight 'pathogenizing' effect in the experimental model used. However, in comparison to the efficiency of handwashing procedures which reduce the number of bacteria available for transfer by at least 3.0 to 4.2 logs, the size of these effects seems to be negligibly small and unpredictable. Therefore, the single most important parameter in assessing the potency of disinfectants remains the reduction of viable counts with time.

1-Propanol↗
PubMed1988

[Synthetic ultrasound blocks and contact gels in sonography: hygienically satisfactory?].

Different sponge-like plastic blocks and several samples of two coupling gels used during small-parts real-time sonography were investigated microbiologically. Whereas the coupling gels showed no contamination a great deal of different bacteria could be found on the plastic blocks. These findings lead to a restricted use of those devices especially when investigating immunocompromised patients. Sufficient procedures of decontamination do not exist. Because of the relative high purchase cost the one-way use of plastic blocks is uneconomical.

Bacteria↗
PubMed1988

[Rapid disinfection of surfaces with a chlorine-releasing scouring agent].

Experiments using artificially contaminated tile-surfaces, broth as well as an artificial soil based on flavour and raw egg as suspension medium for the test-microorganisms (S. aureus, E. coli, P. aeruginosa and C. albicans) resulted in marked inoculum reductions by the following cleaning and disinfection method: a thick, fluid and Chlorine releasing scouring agent was spread onto wetted surface, the surface wiped clean and left for 10 min before being rinsed with tap water. This procedure lead within few minutes to germ reductions similar to those achieved within one or more hours by disinfections with aldehyde based compounds or other well established disinfectants. This fact should be kept in mind when discussing old and new procedures for disinfection of surfaces.

Candida albicans↗
PubMed1988

[High frequency ventilation with a conventional respiratory following heart surgery interventions].

This study was designed to compare the effects of Continuous Positive-Pressure Ventilation (CPPV) and, by using the same unmodified conventional ventilator, High-Frequency Positive-Pressure Ventilation (HFPPVkonv). First, CPPV and HFPPVkonv were studied in a lung model with both normal (R = 5 mbar/1/second) and elevated (R = 20 mbar/1/second) resistance. Our results indicate that in HFPPVkonv the large compressible volume of the conventional ventilator did not influence lung model ventilation at normal resistance. The adjusted (300 ml) tidal volume (VT) and the measured volume of actual expiration (270 ml) were about the same (Fig. 1). However, with elevated resistance air trapping occurred. The large compressible volume influenced model ventilation during both CPPV and HFPPVkonv (Fig. 2). As a second step we evaluated the effects of HFPPVkonv on gas exchange, airway pressure, and hemodynamics in 12 patients (aged 43-69) postoperatively after elective cardiac surgery. After a period of stabilization at the intensive care unit every patient was first ventilated with CPPV. The ventilator settings were: VT = 10-12 ml/kg, inspiratory: expiratory ratio (I:E) = 1:2, frequency (F) = 12/min, V = 60 1/min, PEEP = 5 cm, FiO2 = 40%. After 20 min of CPPV baseline measurements were made (series I). Then the initial ventilator settings of CPPV were switched to HFPPVkonv, the conventional ventilator remaining unmodified. The settings were changed as follows: I:E = 1:3, F = 60/min, V = 120 1/min, PEEP = 5 cm, FiO2 = 40%. During 60 min of HFPPVkonv variables were measured first after 20 min (series II) and again after another 40 min (series III). Minute volume had to be doubled after changing from CPPV to HPFFVkonv to achieve eucapnia. As a result of the new ventilatory settings, VT and hold showed a significant decrease (P less than 0.01) (Table 2).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

PHNO, a novel dopamine agonist, in animal models of parkinsonism.

PHNO, a naphthoxazine compound, was investigated in animal models of central dopaminergic activity. The drug in doses of 5-300 micrograms/kg when administered subcutaneously, or transdermally, induced stereotypic behavior in rats which was blocked by haloperidol but not by reserpine pretreatment. In rats with unilateral 6-hydroxydopamine lesions of the substantia nigra PHNO induced dose-dependent contralateral turnings. The drug caused emesis in dogs and hypothermia in mice. PHNO bound to D-2 dopamine receptors in the rat striatum. Chronic injection with PHNO did not induce behavioral supersensitivity or increase dopamine receptor density. These data indicate that PHNO is a direct acting dopamine agonist that is highly potent. PHNO differs from other dopaminergic drugs and may be useful in the treatment of Parkinson's disease.

Animals↗
PubMed1987

[Artificial ventilation--where is technology going?].

Artificial ventilation plays an important role in prophylaxis and therapy of failure or malfunction of organ systems. Augmented techniques today are used as first choice methods, rather than controlled modes. Strategies for setup of ventilation parameters are necessary in order to achieve reproducible conditions. Constituent part of these strategies is an integrated monitoring which also reflects the invasiveness of the ventilator setting. Such a parameter can be derived by calculating PEEP times I/E-Ratio times FiO2 and is useful for further therapeutic decisions.

Critical Care↗
PubMed1987

Quinpirole hydrochloride, a potential anti-parkinsonism drug.

Quinpirole hydrochloride, a putative dopamine agonist, was investigated in animal models of central dopaminergic activity, to evaluate its possible role in the treatment of Parkinson's disease. The drug induced stereotyped sniffing in rats but, unlike apomorphine, did not produce a maximal behavioural response (stereotyped gnawing). Pretreatment with neuroleptics blocked the stereotypy induced by quinpirole. Quinpirole reversed the effects of reserpine and alpha-methyl-paratyrosine, caused dose-dependent contralateral rotations in rats with unilateral lesions of the substantia nigra induced by 6-hydroxydopamine and induced vomiting in dogs. Small doses of quinpirole decreased locomotor activity, an effect presumably mediated by pre-synaptic autoreceptors. Quinpirole bound to D2 dopamine receptors in the striatum of the rat. The chronic injection of both subthreshold and suprathreshold doses, failed to induce behavioral supersensitivity. These data indicate that quinpirole can stimulate central dopaminergic receptors, and that it is a partial agonist with direct-acting properties. Quinpirole differs from other dopaminergic drugs and may be useful for the therapy of Parkinson's disease.

Animals↗
PubMed1987

Hereditary paroxysmal cerebellopathy: responsiveness to acetazolamide.

We describe kindred in which affected members had paroxysmal attacks of gait ataxia and other cerebellar symptoms. The mode of inheritance was autosomal dominant. Stress or emotion precipitated attacks. Examination between attacks revealed nystagmus but no other neurologic signs. After adulthood there was no progression of symptoms. Acetazolamide therapy successfully abolished the attacks.

Acetazolamide↗
PubMed1987

Caffeine and tremor.

Two percent of normal controls noted that drinking coffee made their hands shaky. Eight percent of essential tremor and 6% of Parkinson's disease patients thought that coffee worsened their tremor. In formal tests, a single oral dose of caffeine (325 mg) did not increase physiologic, essential tremor, or parkinsonian tremor at 1, 2, or 3 hours after ingestion. Caffeine only infrequently induces tremor in normal people, and it does not exacerbate pathologic tremor.

Caffeine↗
PubMed1987

Kinetic predominant essential tremor: successful treatment with clonazepam.

Fourteen patients with marked kinetic tremors of long duration but no other major neurologic signs are described. A positive family history of essential tremor, mild postural tremor, and tremor suppression with alcohol suggest that the condition is a variant of essential tremor. Kinetic tremors had a frequency of 3.5 to 6.0 Hz and an alternating EMG pattern. Propranolol caused improvement in some patients, but clonazepam treatment resulted in tremor suppression in all patients. Kinetic tremor without cerebellar signs is a subtype of essential tremor with pharmacologic responsiveness to clonazepam.

Aged↗
PubMed1987

[Treatment of re-expansion edema ('unilateral ARDS") after rapid pneumothorax drainage].

A rare complication after delayed re-expansion of pneumothorax is reported. A polytraumatized patient with stable vital functions was admitted to our ICU immediately after surgery. Later, oxygenation worsened treated by a rise in FiO2. Concomitant tachycardia was thought to be due to increasing body temperature. On day 3 of treatment in the ICU further deterioration in gas exchange (and in hemodynamics, with complete collapse of the left lung) was diagnosed on X-ray examination. Retrospectively, the development of this condition could be traced on the X-ray films taken during the previous 3 days. Thoracic drainage and suction resulted in complete re-expansion of the lung. After re-expansion worsening of gas exchange and unilateral ARDS-like configurations were observed on chest X-ray. Reversal of the I:E ration and a rise in PEEP improved gas exchange and the X-ray appearance immediately. In the next few days the intensity of the respiratory treatment could be reduced, and after a short period of CPAP the patient was discharged from the ICU. Three mechanisms for development of this "unilateral ARDS" are discussed: loss and suppressed regeneration of surfactant in prolonged atelectic alveolar compartments; increased capillary fluid escape due to suction; and increased complement activation and reduced degradation of edematogenic bradykinin in hypoxic alveolar compartments. Possible clinical implications for the treatment of longer duration pneumothorax are: fractionated drainage and respirator settings, reopening collapsed alveoli in an inhomogeneously diseased lung such as IRV.

Adult↗