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Biomedical subjects

A Forster

Publications and source records attributed to A Forster.

At least 199 records · Page 11Linked to original sources
PubMed1983

[Studying pulmonary mechanics in intensive care].

Assessing pulmonary function in critically ill patients is difficult, mainly because of lack of cooperation, artificial ventilation and jeopardized vital functions. We describe bedside methods and mobile equipment used to measure lung volumes, static pulmonary and thoracic compliance. The analysis of single and multiple-breath nitrogen washout curves allows an estimation of closing volume and an assessment of the inhomogeneity of ventilation. The use of a microcomputer facilitates recording, calculation, reproduction and classification of the data; it also permits the collection of more information in a shorter time, allowing the adjustment of mechanical ventilation to the underlying pulmonary disease.

Critical Care↗
PubMed1983

Effects of midazolam on cerebral hemodynamics and cerebral vasomotor responsiveness to carbon dioxide.

Although it is known that hypercarbia increases and benzodiazepines decrease cerebral blood flow (CBF), the effects of benzodiazepines on CBF responsiveness to CO2 are not well documented. The influence on CBF and CBF-CO2 sensitivity of placebo or midazolam, which is a new water-soluble benzodiazepine, was measured in eight healthy volunteers using the noninvasive 133Xe inhalation method for CBF determination. Under normocarbia, midazolam decreased CBF from 40.6 +/- 3.2 to 27.0 +/- 5.0 ml 100 g-1 min-1 (means +/- SD). At a later session under hypercarbia, CBF was 58.8 +/- 4.4 ml 100 g-1 min-1 after administration of placebo, and 49.1 +/- 10.2 ml 100 g-1 min-1 after midazolam. The mean of the slopes correlating PaCO2 and CBF was significantly steeper with midazolam (2.5 +/- 1.2 ml 100 g-1 min-1 mm Hg-1) than with placebo (1.5 +/- 0.4 ml 100 g-1 min-1 mm Hg-1). Our results suggest that midazolam may be a safe agent to use in patients with intracranial hypertension, since it decreases CBF and thus cerebral blood volume; however, it should be administered with caution in nonventilated patients with increased intracranial pressure, since its beneficial effects on cerebrovascular tone can be readily counteracted by the increase in arterial CO2 tension induced by this drug.

Adult↗
PubMed1983

Noninvasive ventilatory monitoring with bellows pneumographs in supine subjects.

We compared simultaneous measurements of ventilatory movements obtained by a bellows pneumograph (BP) and a respiratory inductive plethysmograph (RIP) vs. integrated volume from a pneumotachograph in seven healthy volunteers during different respiratory patterns. The purpose of this study was to assess if a computer-aided calibration procedure could improve the accuracy of BP, a simple semiquantitative method for noninvasive ventilatory monitoring in supine subjects. Both devices were repeatedly calibrated against a pneumotachograph in the same posture with a computer-aided least-squares method. One calibration maneuver was sufficient to achieve a minimal relative difference in volume measurements between the RIP as well as the BP and the pneumotachograph of less than 1.2 +/- 4.5 (SD) %. The accuracy remained in this range during the subsequent calibrations with time (1 h) and after body movements. However, this difference increased significantly with both devices when the subjects were studied in the lateral decubitus position. The present study indicates that despite theoretical advantages of the RIP, the BP, when properly calibrated, has similar performances in supine subjects for monitoring ventilation; it is simpler and less expensive than the RIP and is devoid of electrical drift and artifacts.

Adult↗
PubMed1983

Respiratory depressant effects of different doses of midazolam and lack of reversal with naloxone--a double-blind randomized study.

Conflicting data concerning the ventilatory effects of benzodiazepines may be caused by the large variability in investigational conditions. Respiratory effects of three different intravenous doses of midazolam (0.05 mg/kg, 0.1 mg/kg, 0.2 mg/kg) and placebo were measured in a double-blind and randomized fashion in eight healthy volunteers. The respiratory variables were analyzed by means of a noninvasive method, thereby avoiding interferences associated with the stimulating effects of mouthpiece and nose clip. After injection of midazolam, tidal volume decreased by 40% with the three doses and respiratory frequency increased to the same extent, minute ventilation remained constant. Only the largest dose of the drug produced a significant decrease (P less than 0.05) in O2 saturation that was related to the longer duration of apnea. Intravenous naloxone (0.015 mg/kg) injected 5 min after midazolam did not change any measured respiratory or hemodynamic variable. We conclude that the respiratory effects of midazolam are poorly dose related and not reversed by naloxone. The observed compensatory increase in respiratory frequency which is not noted in other studies, is probably related to the noninvasive measurement technique used.

Adult↗
PubMed1983

The breakpoint of the Philadelphia chromosome 22 in chronic myeloid leukaemia is distal to the immunoglobulin lambda light chain constant region genes.

Somatic cell hybrids containing chromosomes from a patient with chronic myeloid leukaemia were used as a source of DNA for filter hybridizations with immunoglobulin lambda light chain constant region and c-onc probes. The results show that at least part of the human lambda constant region locus remains on the abnormal chromosome 22 (the Philadelphia chromosome) and therefore that this translocation occurs distal to these genes. Further, in the patient studied the c-abl gene has been translocated to the abnormal chromosome 22, thus creating a new genetic linkage between C lambda and c-abl genes.

Animals↗
PubMed1982

[Monitoring of respiration and respiratory mechanics in intensive care].

Monitoring of respiratory function in the intensive care unit uses different techniques in spontaneously breathing patients and during mechanical ventilation. The simplest and most efficient means are clinical observation, non-invasive monitoring of respiratory movements and frequent blood gas analysis. The respiratory force and reserves can be assessed by measuring tidal volume, vital capacity and maximal inspiratory force (in cm H2O or mm Hg), and these values are helpful in deciding on ventilatory assistance or extubation. During mechanical ventilation the function of the respirator must be monitored by appropriate sensors and alarms. In addition, the measurement of functional residual capacity, compliance and distribution of ventilation, as well as changes therein with the application of positive end-expiratory pressure (PEEP), can contribute to evaluate of appropriate therapy and prognosis of pulmonary failure.

Blood Gas Analysis↗
PubMed1982

[Influence of cimetidine on bacterial growth in gastric fluid (author's transl)].

Samples of gastric fluid were tested for pH and number of bacteria in 20 patients who received cimetidine 400 mg prior to selective gastric surgery. The results were compared with those obtained in a group of surgical patients who did not receive the drug. The cimetidine-treated patients had alkaline gastric fluid with pronounced bacterial growth (4.7 +/- 0.6 x 10(4) micro-organisms/ml), whereas 18/20 untreated patients has a sterile gastric fluid. Similar results were observed in 14 intensive care patients treated for 24 hours with cimetidine. The effect proved reversible: 12 hours after treatment was discontinued bacterial growth could only be demonstrated in 3/14 patients. Thus, short-term cimetidine treatment results in a rise of gastric pH with marked bacterial proliferation. This may have serious consequences in cimetidine-treated patients about to undergo gastric surgery or likely to develop aspiration pneumonia.

Bacteria↗
PubMed1982

Evaluation of a new monitoring device for arterial blood pressure and heart rate measurement by automatic sphygmomanometry.

Measurements of arterial blood pressure (BP) and heart rate (HR) using a new non-invasive automatic apparatus were compared with the BP and HR values obtained with an invasive technique, i.e. arterial catheter and pressure transducer. This new device consists of a self-inflating BP cuff and of a microphone which converts Korotkoff sounds into digital values. The comparison was made on 400 measurements in 10 surgical intensive-care patients during 18 hours after open heart surgery. Systolic pressure was underestimated by the new device by 13 +/- 20 mm Hg/1.7 +/- 2.6 kPa (means +/- SD) and the linear correlation coefficient between the non-invasive and the invasive technique was r = 0.70. Diastolic pressure was overestimated by 9.4 +/- 12.0 mmHg (1.2 +/- 1.5 kPa) with an r = 0.63. HR was also underestimated by 7 +/- 17 heart beats per minute (r = 0.58). We conclude that this new device is not adequate for monitoring intensive-care patients, not so much because of the differences noted between the invasive and the non-invasive measurements, but in particular because there are no alarms, no mean arterial pressure measurement and also because it gives aberrant results once out of twenty measurements.

Anesthesia, General↗
PubMed1982

I.v. labetalol in the treatment of hypertension following coronary-artery surgery.

The cardiovascular effects of incremental fixed i.v. doses of labetalol were evaluated in 10 normovolaemic sedated patients presenting with hypertension and tachycardia in the early period after myocardial revascularization. At first dose of 20 mg was sufficient to provoke a significant (P less than 0.01) mean decrease in systolic (-9.3%), diastolic (-8.2%) and mean arterial (-7.9%) pressure (AP) and in the rate-pressure product (RPP) (-13.1%). The mean heart rate (HR) did not change significantly, but a linear correlation could be established between the change at 2 min and the value before injection (r = 0.73). A second dose of labetalol 40 mg given 5 min later did not decrease AP further, but a significant decrease in HR was noted. A marked difference in the individual response among patients was found as the range of effective total doses per kg body weight was 0.6-4.1 mg kg-1 (mean 2.2) Apart from one patient, no patient needed vagolytic or sympathomimetic drugs to oppose the alpha or beta actions of labetalol during the 24-h follow-up period.

Aged↗
PubMed1982

Effects of midazolam on cerebral blood flow in human volunteers.

The effects of intravenously administered midazolam on cerebral blood flow were evaluated in eight healthy volunteers using the 133Xe inhalation technique. Six minutes after an intravenous dose of 0.15 mg/kg midazolam, the cerebral blood flow decreased significantly (P less than 0.001) from a value of 40.6 +/- 3.3 to a value of 27.0 +/- 5.0 ml . 100 g-1 . min-1. Cerebrovascular resistance (CVR) increased from 2.8 +/- 0.2 to 3.9 to 0.6 mmHg/(ml . 100 g-1 . min-1)(P less than 0.001). Mean arterial blood pressure decreased significantly (P less than 0.05) from 117 +/- 8 to 109 +/- 9 mmHg and arterial carbon dioxide tension increased from 33.9 +/- 2.3 to 38.6 +/- 3.2 mmHg (P less than 0.05). Arterial oxygen tension remained stable throughout the study, 484 +/- 95 mmHg before the administration of midazolam and 453 +/- 76 mmHg after. All the subjects slept after the injection of the drug and had anterograde amnesia of 24.5 +/- 5 min. The decrease in mean arterial blood pressure was probably not important since it remained in the physiologic range for cerebral blood flow autoregulation. The increase in arterial carbon dioxide tension observed after the midazolam injection may have partially counteracted the effect of this new benzodiazepine on cerebral blood flow. Our data suggest that midazolam might be a safe agent to use for the induction of anethesia in neurosurgical patients with intracranial hypertension.

Adult↗
PubMed1981

Human immunoglobulin heavy chain genes: evolutionary comparisons of C mu, C delta and C gamma genes and associated switch sequences.

Human immunoglobulin heavy chain constant region genes have been characterised in isolated clones. The human c mu gene comprises discrete domains for C mu 1, C mu 2, C mu 3 and C mu 4 + tp separated by short intervening sequences. The C delta gene has been located about 5 kb downstream of C mu 4. Furthermore, the coding segments for the membrane form of mu have been located 1.9 kb downstream of C mu 4. Tandemly repeated sequences implicated in the heavy chain class switch occur upstream of the C mu and the C gamma genes, but none were detected near the C delta gene. These tandem repeats are very homologous to those of mouse. Particularly common is the sequence G-A-G-C-T. These data suggest that the mu to gamma switch in humans involves DNA rearrangements of the CH-genes and subsequent deletion of DNA, but that the coexpression of C mu and C delta genes results from different mechanisms.

Amino Acid Sequence↗