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Biomedical subjects

H Langenstein

Publications and source records attributed to H Langenstein.

At least 19 recordsLinked to original sources
PubMed1997

[Safe handling of the laryngeal mask airway in eye surgery].

BACKGROUND: We prospectively used the laryngeal mask airway (LM) in eye surgery to evaluate: 1) the limits of safe handling; 2) the feasibility of its use in long operative procedures, and 3) whether patients with higher anaesthetic risk (hypertension, asthma, children) may profit from the LM. METHODS: In 792 patients leak pressure, cuff volume, duration of anaesthesia, and complications were noted; 33 were children under 10 years of age, 100 had hypertension or severe asthma. In 54 patients cuff volume was increased to measure its influence on leak pressure; in 241 leak pressure was also measured at the end of the procedure; in 31 cuff pressure was measured under standard conditions over time; in 7 dead space was evaluated with the BANALYZER program; and in 300 blind endotracheal suction was attempted through the LM. RESULTS: Limits for the safe use of the LM were a leak pressure < 12 cm H2O combined with insufficient spontaneous ventilation (CO2et > 7 vol.%; n = 14), dislocation with gastric inflation (n = 2), and bronchial secretions (n = 1), as blind suctioning of the trachea through the LM was possible in only 1 out of 300 attempts. These limits could be recognised before the start of the operation in most cases. Laryngospasm or closure of the glottis (n = 36, 4.5%) was treatable and did not necessitate abandoning the use of the LM. Mean leak pressure was 17.7 +/- 4.8 cm H2O, showing a comparable distribution in adults and in children and being improved mainly by position changes of the LM, but not by changes in cuff volume. No gas leak occurred when the individual peak inspiratory pressure was equal to or lower than the measured leak pressure except in children. Dead space was almost halved by the LM compared to a face mask (90 +/- 13 vs. 162 +/- 31 ml; P < 0.05), allowing spontaneous breathing to be adequate even when manual assistance of ventilation was not possible (n = 14, 1.8%). In patients with sufficiently high leak pressures, the LM was safely used for long operations (up to 240 min), as leak pressure did not change over time. When only a low leak pressure could be achieved, deep breaths could be delivered by prolongation of the inspiratory time, thereby preventing atelectasis if tidal volume was limited. Cuff pressure rose to about 100 cm H2O within 60 min and should be monitored. In children, air was aspirated intermittently out of the stomach in procedures longer than 30 min; in adults, we monitored and buffered gastric contents where necessary. In patients at risk, the LM stimulates the circulation and bronchial reactivity less than an endotracheal tube. Children could be discharged earlier from the recovery room (0.45-1.5 h vs. > or = 2 h after neuromuscular relaxation and intubation). CONCLUSION: Limits for the use of the LM in eye surgery are delineated. Within these limits, the LM offers control over the airway comparable to that of an endotracheal tube with less stimulation. The LM has to be applied by an experienced user, and has advantages in eye surgery.

Adolescent↗
PubMed1996

[Difficult intubation in adults].

GOAL OF THIS REVIEW: We review the recent literature and our experience in order to determine how one can recognize and handle patients with difficult endotracheal intubation. DEFINITION AND INCIDENCE: "An intubation is called difficult if a normally trained anesthesiologist needs more than 3 attempts or more than 10 min for a successful endotracheal intubation." The incidence of difficult intubation depends on the degree of difficulty encountered showing a range of 1-18% of all intubations to about 2/10000-1/million for "cannot ventilate-cannot intubate" situations. Three "cannot ventilate-cannot intubate" situations are presented that occurred at our institution in the last 10 years out of about 85000 anaesthesias. PREOPERATIVE RECOGNITION: Intubation will be overtly difficult in patients with a small mouth opening, protruding upper teeth, a stiff neck, engorgement of the tongue, cervical swelling after an operation for a face tumour, or in patients with an unstable cervical spine. In about 50-70%, a difficult intubation can be detected preoperatively in patients with grossly normal cervical anatomy by three indirect signs: if the soft palate cannot be visualized (Mallampati classification), if the inframandibular space is smaller than normal, and if the mobility of the atlanto-occipital joint is reduced to below 15 degrees. It is essential that these indirect parameters be tested preoperatively, especially in patients in whom general anaesthesial is planned for a caesarean section or if an ileus intubation is planned. HANDLING: General handling of difficult intubation, use of special material including a portable unit, and confirmation of the endotracheal position of an endotrachaeal tube are outlined (CO2 et, SaO2, fibreoptic bronchoscopy, direct visualization of the translaryngeal position of the tube). The laryngeal mask airway, transtracheal jet ventilation, and the mini-coniotomy are selectively presented as alternative airways. The American Society of Anesthesiologists' (ASA) difficult airway algorithm is presented. CONCLUSION: With better preoperative evaluation and clear guidelines and training for difficult intubation anaesthetic morbidity and mortality can be reduced.

Adult↗
PubMed1996

[Inspiratory pressure support via facial mask in acute respiratory insufficiency].

A patient in acute respiratory failure (Murray score 2.0) caused by pneumonia in the remaining lung 4 days after left-sided pneumonectomy was successfully treated with non-invasive pressure support by face mask. Non-invasive ventilation was chosen to keep the time of ventilating as short as possible, to achieve minimum pressure within the airways, and to retain natural defense and clearance mechanisms. Inspiratory pressure support was added to reduce increased work of breathing, improve ventilatory mechanics and gas exchange. Also, intrinsic PEEP was counterbalanced by external PEEP of 5 cmH2O to reduce work of breathing. Inspiratory pressure support of 15 cmH2O reduced respiratory rate to less than 30 breaths/min, improved paO2 and reduced elevated paCO2 towards normal within 3 hours. Duration of the non-invasive ventilation was 45 hours. There were no complications.

Carcinoma, Bronchogenic↗
PubMed1995

[The laryngeal mask airway in the difficult intubation. The results of a prospective study].

OBJECTIVE: The laryngeal mask airway (LMA) was prospectively used in patients who were difficult to intubate to evaluate whether it improves ventilation compared to a face mask, facilitates fibreoptic intubation, and how often blind intubation would be possible. METHODS: In a university hospital, 30 patients who were difficult to intubate (35 operative procedures) and 50 normal subjects were investigated; 23 patients had had radical resection of a facial tumor with irradiation at a previous time and 7 could not be intubated conventionally (grade 3 and 4 visibility of the larynx according to Cormack [14]). Blind intubation was attempted with a bent bougie, a 6.0-mm uncuffed tube, or a straight bougie. RESULTS: Insertion of the LMA was possible in all except 1 patient with a mouth opening of 1 cm. Ventilation via the LMA was always excellent and, for tumor patients, superior to a face mask. In tumor patients, leak pressure was higher than in patients with normal cervical anatomy either with or without difficult intubation conditions (25.2 +/- 7.9, P < 0.05, vs. 20.8 +/- 4.4 vs. 20.6 +/- 4.9 cmH2O; n.s.; Fig. 2). Fibreoptic intubation through the LMA was successful in all cases and easier than via a nasal or oral route. Blind intubation was successful in 22% of difficult to intubate patients and 19% of normals, mainly using a 6.0 mm uncuffed endotracheal tube. Substitution of an uncuffed oral tube inserted via the LMA by a nasal endotrachel tube using a reinforced stomach tube is described (Fig. 4). CONCLUSION: The LMA improves ventilation, facilitates fibreoptic intubation, and offers the possibility for blind endotracheal intubation in difficult to intubate patients. Blind intubation though the LMA has to be practised extensively to have a high success rate. The LMA represents an additional aid for the anaesthetic management of patients who are difficult to intubate.

Anesthesia↗
PubMed1993

[Quantifying pathological disorders of consciousness. Reliability criteria, aims, feasibility].

Within a survey of coma scales we distinguish scales of clinical findings (Glasgow Coma Scale [GCS], Glasgow Liège Scale [GLS], Innsbruck Coma Scale [ICS], Comprehensive Level of Consciousness Scale [CLOCS]), grading tests (Vigilance Scale [VS], Funktionspsychose-Skala-B [FPBS-B]) and level-scales (Reaction-Level-Scale [RLS-85], Munich Coma Scale [MCS]). With regard to the purpose we differentiate a classification of depth, the prediction of prognosis and the monitoring of changes. For the purpose of classification of depth, the RLS-85 because of its superior objectivity is preferable, but the GCS is of comparable validity and more widely used. The GLS differentiates the deeper states of coma better than either of these because brainstem-reflexes in cranio-caudal order are added. Within the prediction of prognosis all coma-scales have only limited validity and for the purpose of resource economy require additional criteria in the individual case. For the purpose of monitoring changes the level-scales primarily do not fit, the GCS is not sensitive enough. The Glasgow-Cologne-List is better suited; it is more than one-dimensional, but can be expressed through the GCS numbers for comparative purposes. The ICS is not widely used and the prognostic validity has not been proven to the same extent. The Glasgow-Cologne-List could be amplified for the less severe disturbances of consciousness according to Price (32,33), and for the lower levels according to the GLS (2,3,4). In both cases the expense is slightly higher.(ABSTRACT TRUNCATED AT 250 WORDS)

Brain Damage, Chronic↗
PubMed1991

[Diagnosis of brain death: limitations of angiography after osteoclastic trepanation].

A 50-year-old man sustained severe skull-brain trauma with intracerebral bleeding, cortical contusion foci and fracture of the petrosal bone. He went into coma a few hours after the accident. Three days after surgical removal of an intracerebral bleeding via a frontoparietal osteoclastic trepanation (removal of a 4 x 5 cm piece of bone) there occurred complete brainstem areflexia, respiratory arrest and drop in temperature; the encephalogram was isoelectric. There was thus no clinical-neurological doubt of brain death. But cranial digital subtraction angiography, generally considered to give the most reliable evidence of irreversible loss of cerebral functions, showed contrast medium in the branches of the left cerebral artery. The diagnostic criteria of brain death, as proposed by the Federal German Chamber of Physicians (Bundesärztekammer), were thus not exactly met, and despite the clinically obvious brain death a contemplated removal of organs for transplantation was therefore not undertaken. The patient died 6 hours after the angiography. This case shows that the value of angiography for the diagnosis of brain death may sometimes be limited, at least in those cases in which osteoclastic trepanation has been performed or there are other causes for a skull defect, because they can prevent the rise of intracranial pressure which brings about the cerebral circulatory arrest.

Angiography, Digital Subtraction↗
PubMed1991

Continuous positive pressure breathing without and with inspiratory pressure support in acute respiratory failure when mean airway pressure is constant.

OBJECTIVE: Mean airway pressure (Pawm) may be a major factor for PaO2, functional residual capacity, and cardiac output in acute respiratory failure (ARF). To clarify effects of inspiratory pressure support (IPS) as a ventilatory mode in ARF, we studied patients in ARF either using IPS or continuous positive pressure breathing (CPAP) at the same level of Pawm, measuring respiratory and circulatory parameters. METHODS: After consent, 10 patients in ARF of moderate severity (PaO2:FiO2 205 +/- 108 at positive end expiratory pressure (PEEP) 8.7 +/- 3.1 cmH2O; mean +/- SD) were investigated. Measurements were on day 7.4 +/- 8.4 after onset of ARF. IPS was 13.5 +/- 3.9 cmH2O above PEEP. To result in constant Pawm, PEEP was reduced for IPS (Pawm IPS 11.1 +/- 3.6 vs. Pawm CPAP 9.9 +/- 3.3 cmH2O, ns; PEEP IPS 8.7 +/- 3.1 vs. PEEP CPAP 10.6 +/- 4.3 cmH2O, p = 0.04). Inspired concentration of oxygen (FiO2) and the ventilator (Siemens 900 C) were not changed for the individual patient. RESULTS: For IPS, tidal volume (VT) increased by +31% and respiratory frequency (RF) decreased by -19% (VT IPS 608 +/- 179 vs. VT CPAP 465 +/- 141 ml, p = 0.01; RF IPS 21.6 +/- 7.6 vs. RF CPAP 26.7 +/- 8.3 breaths per minute, p = 0.02). Also, PaCO2 showed a tendency to be lower for IPS, not reaching significance (PaCO2 IPS 44.3 +/- 5 vs. PaCO2 CPAP 47.4 +/- 4.9 mmHg, p = 0.1). All other parameters were unchanged (expiratory minute volume, PaO2, pH, intravascular pressures, cardiac index, stroke volume index (n = 6), systemic and pulmonary vascular resistances, venous admixture, deadspace (n = 3), oxygen consumption and oxygen delivery). WE CONCLUDE: When Pawm remained constant, IPS added to CPAP improved VT and RF without improving oxygenation or deteriorating circulation in patients with ARF of moderate severity. IPS mainly supports the ability to breathe spontaneously in ARF.

Acute Disease↗
PubMed1986

[Emergency ventilation using an Ambu-bag with a new coniotomy set].

A new coniotomy set (Mini-Trach, Portex Ltd) for endotracheal suction was modified with a 4-mm tube adapter and used for ventilation with standard resuscitation bags (Ambu, Laerdal) in two corpses. Minute volumes achieved with open glottis were 36 +/- 1.9 l/min for Ambu, 33 +/- 2.8 l/min for Laerdal, and 16 +/- 1.1 l/min for a standard anaesthesia machine, respiratory frequencies were 51 +/- 5.3/min, 46 +/- 8.9/min, and 30 +/- 3.3/min respectively. Auscultation and inspection showed good ventilation of both lungs. We conclude that this coniotomy set is suitable for emergency ventilation by standard resuscitation bags until a definite airway can be established; it permits higher flow than needle coniotomy and avoids most of its complications. Care must be taken when outflow must also be achieved by the same cannula.

Emergencies↗
PubMed1985

Reliable detection of inspiration and expiration by computer.

A new computer assisted method is proposed to distinguish between the inspiratory and expiratory phases of breathing. The method is based on the analysis of both gas flow and CO2-concentration. The algorithm is effective and reliable and is most suitable in critical care patients when an uninterrupted sequence of breaths is to be analysed immediately at the bedside. Marked variations in tidal volume such as are seen in intermittent mandatory ventilation or spontaneous breathing during the phase of weaning from the ventilator, artefacts such as mechanical vibrations of the flow transducer or its connecting tubes do not disturb the analysis.

Computers↗
PubMed1985

A simple method for estimating compliance.

In intensive care medicine, pulmonary compliance is one of the very helpful diagnostic indices. Because of technical difficulties, however, the measurement of pulmonary compliance is often reduced to a rough guess of the compliance of the total respiratory system. The technical problems can be overcome using a computer to solve the basic equations with the least-squares fit (LSF) method. Unfortunately, this method requires such a long calculation time that bedside breath-by-breath calculations are impracticable on small computers. A simple computer algorithm (mean-values method) was therefore developed and compared to the LSF method. Compliance values calculated by either procedure were practically identical in ventilated patients. However, by reducing computing time to 30% of the LSF method, our mean-values algorithm enabled real-time estimation of compliance breath-by-breath.

Humans↗
PubMed1985

Accurate measurement of N2 volumes during N2 washout requires dynamic adjustment of delay time.

Measurement of respiratory gas composition by a mass spectrometer lags behind the measurement of gas flow. To obtain specific gas volumes (e.g., the N2 volume) by multiplication and integration of concentration and flow, one has to synchronize flow and concentration signals using the delay time (TD) of the gas analyzer. During the N2 washout, however, gas composition changes and causes alterations of TD. This leads to errors of up to 17 and 70% in the measurement of pulmonary volume and series dead space, respectively, in an ideally mixing physical model of the lung. On the basis of Poiseuille's law and exact measurements of the characteristics of the capillary it is possible to adjust the synchronization, which improves the absolute accuracy considerably.

Animals↗
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↗