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Biomedical subjects

H Langenstein

Publications and source records attributed to H Langenstein.

27 records · Page 2Linked to original sources
PubMed1983

[The impossibility of direct flow measurements in lung function studies. Analysis of errors and compensation].

The authors demonstrate that the conditions for correct flow measurement are not fulfilled when a resistive flow transducer (Fleisch pneumotachograph, screen pneumotachograph etc.) is connected directly to the mouth or to the end of the endotracheal tube. This is because the composition, temperature and water content of the respiratory gas varies markedly within a respiratory cycle, the mechanically ventilated patient exhales with a huge expiratory initial peak flow, and laminar flow tends to switch over to turbulent flow in this system. Methods are proposed of continuously compensating the effects of changing gas composition, reducing expiratory peak flow without an increase in expiratory resistance, and preventing the occurrence of turbulent flow. The improvement of measuring accuracy to 2% makes the estimation of respiratory volumes more reliable. Secondly, the increased quality of primary data enables one to analyze these data in a more complex and sophisticated manner (N2-washout compartment analyses, VDS, investigation of complicated modes of ventilation such as IMV, etc.).

Humans↗
PubMed1983

[Behavior of functional residual capacity in acute respiratory insufficiency].

Variations of functional residual capacity (FRC, estimated by the N2-washout technique) and oxygenation (PaO2/FIO2) were investigated in patients mechanically ventilated for acute respiratory failure (ARF, caused by pneumonia). The various ventilatory modes were compared. The results were as follows: 1. If FRC is reduced due to ARF, the reduction is diminished by PEEP. The quantitative amount of this effect cannot be predicted in the individual patients. 2. If CPPV is switched to IMV or CPAP with an equal PEEP value, FRC was not usually changed when the clinical course was favourable; however, FRC decreased if clinical signs of insufficient spontaneous respiration were present. The proportion of FRC reduction following such a change of respiratory mode was equal to the effect of removal of PEEP from 10 cm H2O to zero. 3. FRC and oxygenation do not undergo a parallel change in every situation. 4. Treatment and further research should focus not only on increasing reduced lung volume but mainly on diverting ventilation to perfused lung regions.

Acute Disease↗
PubMed1983

Direct accurate gas flow measurement in the patient: compensation for unavoidable error.

It is shown that the conditions for accurate flow measurement are not met if the resistant flow meter (e.g., Fleisch pneumotachograph or screen pneumotachograph) is attached directly at the mouth or endotracheal tube and the breath flows directly through it, firstly because its gas composition, temperature, and humidity change radically even within the course of one respiratory cycle, secondly because the expiratory peak flow of the patient being ventilated rapidly tends to become too high, and thirdly because the entire system is sensitive to turbulence. Methods are proposed to compensate continuously for the influence of the changing gas concentrations and to reduce expiratory peak flow without increasing resistance. With the resulting reduction in the error from 20% to about 2%, tidal volume can be more reliably determined, and the higher quality of primary data allows a more differentiated and more complex evaluation (N2-washout compartment analysis, VDS measurement, analysis of complicated patterns of spontaneous breathing or mechanical ventilation such as IMV, etc.).

Humans↗
PubMed1982

[Catheter epidural analgesia for treatment of postoperative and post-traumatic pain].

Postoperative epidural local anesthetics or opiates provide excellent analgesia but do not reduce the incidence of respiratory complications compared with systemic analgesics. Additional and sometimes lethal side effects reserve the routine use of epidural analgesia for highly selected patients. Thoracic epidural analgesia (TEA) may prevent ventilation in patients with serial rib fractures (SRF) without gross pulmonary parenchymal lesion. TEA results in fewer pulmonary complications, shorter hospital stay, and lower mortality than artificial respiration. Late global pulmonary tests after TEA for treatment of SRF show normal results within comparable groups without rib fractures.

Abdominal Injuries↗
PubMed1982

Optimal endexpiratory airway pressure for ventilated patients.

In patients ventilated for acute respiratory failure PEEP was changed either by gradual increase and decrease (5 cm H2O/min) or in steps of 5 cm H2O. The effects on gas exchange, pulmonary mechanics and pulmonary and systemic circulation were studied. Total compliance did not change uniformly and cardiac index decreased so much due to PEEP that the increase in PaO2 could not prevent the decrease of arterial oxygen transport. No variable was found helpful to predict the "best PEEP" in a clinical situation.

Blood Circulation↗
PubMed1982

A concept for breath by breath computing of lung compliance in the ventilated patient.

A concept for calculating dynamic lung compliance (CL) by computer in ventilated supine patients is described. The primary signals are gas flow, airway pressure, esophageal pressure (PES) and ECG. Endinspiratory and endexpiratory PES is calculated as a mean value during an R/R interval's time just before the end of inspiration and expiration. Its main advantage is a reduction of the variability in computer calculated CL by reducing the influence of cardiac oscilliations on PES tracings, thus enabling evaluation of special ventilatory settings as intermittent mandatory ventilation or rapidly changing PEEP.

Computers↗
PubMed1981

[Acute heart insufficiency of primarily non-cardiac origin after polytrauma].

UNLABELLED: The following approach is proposed for treatment of the hemodynamics resulting from severe trauma. Blood pressure and pulse frequency are measured whilst volume is added until peripheral circulation returns to normal or until CVP attains 13 mm Hg (under CPPV, PEEP 10 cm H2O). When CVP attains 13 mm Hg a pulmonary-arterial thermodilution catheter is introduced and transfusion continued, possibly up to a PCWP of 17 mm Hg. At this stage, 4 different haemodynamic groups may be distinguished and are described on the basis of the mean values recorded for 3 patients in each group: 1. SVRI increased, LVSWI and PVRI normal. THERAPY: continued slow addition of volume. 2. SVRI and PVRI slightly elevated. LVSWI diminished. CI and VO2 adequate. THERAPY: phentolamine. 3. PVRI slightly elevated, CI and VO2 too low, i.e. left cardiac insufficiency. THERAPY: isuprel. 4. PVRI markedly elevated, CI and VO2 clearly diminished, i.e. biventricular cardiac insufficiency with pulmonary-vascular hypertension. THERAPY: isuprel and phentolamine. Pharmacological therapy can be discontinued after a few days and hemodynamics remain normal. These observations show that "acute cardiac failure in fundamentally normal hearts" can occur after severe trauma and that treatment is possible.

Blood Volume↗