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Biomedical subjects

W Heinrichs

Publications and source records attributed to W Heinrichs.

At least 19 recordsLinked to original sources
PubMed2000

Component analysis of verbal fluency in patients with schizophrenia.

OBJECTIVE: Clustering and-switching components of phonemic fluency performance were compared in patients with schizophrenia and healthy normal controls. BACKGROUND: These components were selected to provide evidence for a specific anatomic locus for the breakdown of language processes or for a multiple-disease model of schizophrenia. METHOD: As part of a larger battery of neuropsychological tests, phonemic fluency tests were administered on an individual basis. On separate 60-second trials, participants were instructed to generate words beginning with the letters C, F, and L, excluding proper names and variants of the same word. Three scores were obtained for each participant: (1) number of words generated, excluding errors and repetitions; (2) mean cluster size; and (3) raw number of switches. RESULTS: The patients showed small but significant impairments in clustering and larger impairments in switching relative to normal controls. CONCLUSIONS: This pattern suggests a relatively greater deficit in functioning in the frontal lobe than in the temporal lobe. However, neither measure was able to completely discriminate patients with schizophrenia from controls. Moreover, differences in fluency performance were observed among subtypes of schizophrenia. Taken together, the findings of impaired performance for both aspects of fluency, differences between subtypes, and the failure to completely discriminate patients with schizophrenia from controls indicate that there is not a single marker of the disease, at least among these fluency variables. Instead, the current findings are more supportive of a multiple-disease model of schizophrenia.

Adult↗
PubMed1999

Successful treatment of a patient with ARDS after pneumonectomy using high-frequency oscillatory ventilation.

High frequency oscillatory ventilation (HFOV) was used in a patient who developed the acute respiratory distress syndrome 5 days following a right pneumonectomy for bronchogenic carcinoma. When conventional pressure-controlled ventilation failed to maintain adequate oxygenation, HFOV dramatically improved oxygenation within the first few hours of therapy. Pulmonary function and gas exchange recovered during a 10-day period of HFOV. No negative side effects were observed. Early use of HFOV may be a beneficial ventilation strategy for adults with acute pulmonary failure, even in the postoperative period after lung resection.

Airway Resistance↗
PubMed1999

Computed tomography-based tracheobronchial image reconstruction allows selection of the individually appropriate double-lumen tube size.

OBJECTIVES: To determine whether individualized selection of double-lumen tubes or alternatives based on three-dimensional reconstruction of the tracheobronchial image from routine preoperative computed tomography (CT) scans leads to clinically appropriate choices. DESIGN: Prospective observational study; comparison to historic controls. SETTING: Anesthesia and radiology facilities of a university medical center. PARTICIPANTS: Forty-nine patients undergoing thoracic surgery requiring one-lung ventilation. INTERVENTIONS: Three-dimensional image reconstruction of individual tracheobronchial anatomy was performed from routine preoperative spiral CT scans as well as from scans of five left-sided and four right-sided double-lumen tubes. Results of image-based tube size selection were compared with literature recommendations. Prospectively, individualized tube selection was performed by superimposition of printed transparencies of tubes over the tracheobronchial system and was validated using bronchoscopic and clinical criteria (n = 24). MEASUREMENTS AND MAIN RESULTS: Three-dimensional reconstruction visualized individual anatomy with good accuracy and resolution. Correlations between patient morphology and tracheobronchial dimensions were weak (height versus mainstem bronchial diameters: r < 0.50). In 11 of 48 patients (23%). CT-fitted double-lumen tube sizes would have differed from a conventional height-based and gender-based selection. Individual, prospective, CT-based double-lumen tube selection was associated with (1) good fit and positioning confirmed by fiberoptic bronchoscopy, (2) adequate bronchial cuff seal volumes, (3) complete lung separation, and (4) oxygenation and ventilation parameters during one-lung ventilation similar to those with conventional size selection. In one patient, three-dimensional CT study allowed noninvasive evaluation of a tracheal stenosis precluding double-lumen tube placement. CONCLUSION: Individualized selection of double-lumen tube size using CT-based reconstructions of tracheobronchial anatomy leads to clinically appropriate choices. Risks resulting from variations in tracheobronchial morphology are recognized in advance.

Adolescent↗
PubMed1999

[Multi-rotation CT during continuous ventilation: comparison of different density areas in healthy lungs and in the ARDS lavage model].

PURPOSE: In this animal study, density ranges for CT-based quantification of ventilated lung area were determined. Healthy lungs and ARDS lungs were compared during artificial respiration. MATERIAL AND METHODS: CT-scans were performed in 5 anesthetized pigs using a dynamic multiscan CT option on a predefined transverse slice (slice thickness 1 mm; effective temporal resolution, 250 ms). During continuous CT acquisition, airway pressure was increased or decreased in a stepwise manner. In all images, areas of defined HU ranges were determined planimetrically. The lower threshold was set to -910 HE in all images. The upper threshold was varied from -800 HE to -200 HE in steps of 100 HE. RESULTS: During inspiration in healthy lungs the HU-range of -910 to -700 HU showed the largest increase in area. During inspiration in ARDS lungs the HU range from -910 to -300 HU allowed the most sensitive assessment of area changes. These findings can be explained by recruitment of atelectases (HU-range > -300 HU) and their transition to a HU range from -700 to -300 HU. CONCLUSION: Dynamic multiscan CT acquisitions are a useful method to determine changes of ventilated lung area during a respiratory cycle. Different HU-ranges are required to access volume changes in healthy lungs and in ARDS lungs.

Animals↗
PubMed1998

Adaptive lung ventilation (ALV) during anesthesia for pulmonary surgery: automatic response to transitions to and from one-lung ventilation.

UNLABELLED: Adaptive lung ventilation is a novel closed-loop-controlled ventilation system. Based upon instantaneous breath-to-breath analyses, the ALV controller adjusts ventilation patterns automatically to momentary respiratory mechanics. Its goal is to provide a preset alveolar ventilation (V'A) and, at the same time, minimize the work of breathing. Aims of our study were (1) to investigate changes in respiratory mechanics during transition to and from one-lung ventilation (OLV), (2) to describe the automated adaptation of the ventilatory pattern. METHODS: With institutional approval and informed consent, 9 patients (33-72 y, 66-88 kg) underwent ALV during total intravenous anesthesia for pulmonary surgery. The ALV controller uses a pressure controlled ventilation mode. V'A is preset by the anesthesiologist. Flow, pressure, and CO2 are continuously measured at the DLT connector. The signals were read into a IBM compatible PC and processed using a linear one-compartment model of the lung to calculate breath-by-breath resistance (R), compliance (C), respiratory time constant (TC), serial dead space (VdS) and V'A. Based upon the results, the controller optimizes respiratory rate (RR) and tidal volume (VT) such as to achieve the preset V'A with the minimum work of breathing. In addition to V'A, only PEEP and FIO2 settings are at the anesthesiologist's discretion. All patients were ventilated using FIO2 = 1,0 and PEEP = 3 cm H2O. Parameters of respiratory mechanics, ventilation, and ABG were recorded during three 5-min periods: 10 min prior to OLV (1), 20 min after onset of OLV (II), and after chest closure (III). Data analyses used nonparametric comparisons of paired samples (Wilcoxon, Friedman) with Bonferroni's correction. Significance was assumed at p < 0.05. Values are given as medians (range). RESULTS: 20 min after onset of OLV (II), resistance had approximately doubled compared with (1), compliance had decreased from 54 (36-81) to 50 (25-70) ml/cm H2O. TC remained stable at 1.4 (0.8-2.4) vs. 1.2 (0.9)-1.6) s. Institution of OLV was followed by a reproducible response of the ALV controller. The sudden changes in respiratory mechanics caused a transient reduction in VT by 42 (8-59)%, with RR unaffected. In order to reestablish the preset V'A, the controller increased inspiratory pressure in a stepwise fashion from 18 (14-23) to 27 (19-39) cm H2O, thereby increasing VT close to baseline (7.5 (6.6-9.0) ml/kg BW vs. 7.9 (5.4-11.7) ml/kg BW). The controller was, thus, effective in maintaining V'A. The minimum PaO2 during phase II was 101 mmHg. After chest closure, respiratory mechanics had returned to baseline. CONCLUSIONS: Respiratory mechanics during transition to and from OLV are characterized by marked changes in R and C into opposite directions, leaving TC unaffected. The ALV controller manages these transitions successfully, and maintains V'A reliably without intervention by the anesthesiologist. VT during OLV was found to be consistently lower than recommended in the literature.

Adult↗
PubMed1998

Laryngeal mask airway position and the risk of gastric insufflation.

UNLABELLED: A potential risk of the laryngeal mask airway (LMA) is an incomplete mask seal causing gastric insufflation or oropharyngeal air leakage. The objective of the present study was to assess the incidence of LMA malpositions by fiberoptic laryngoscopy, and to determine their influence on gastric insufflation and oropharyngeal air leakage. One hundred eight patients were studied after the induction of anesthesia, before any surgical manipulations. After clinically satisfactory LMA placement, tidal volumes were increased stepwise until air entered the stomach, airway pressure exceeded 40 cm H2O, or air leakage from the mask seal prevented further increases in tidal volume. LMA position in relation to the laryngeal entrance was verified using a flexible bronchoscope. The overall incidence of LMA malpositions was 40% (43 of 108). Gastric air insufflation occurred in 19% (21 of 108), and in 90% (19 of 21) of these patients, the LMA was malpositioned. Oropharyngeal air leakage occurred in 42%, and was independent of LMA position. We conclude that clinically unrecognized LMA malposition is a significant risk factor for gastric air insufflation. IMPLICATIONS: Routine placement of laryngeal mask airways does not require laryngoscopy. In our study, fiberoptic verification of mask position revealed suboptimal placement in 40% of cases. Such malpositioning considerably increased the risk of gastric air insufflation.

Adult↗
PubMed1997

[Automated anesthesia record systems].

The introduction of electronic anaesthesia documentation systems was attempted as early as in 1979, although their efficient application has become reality only in the past few years. The advantages of the electronic protocol are apparent: Continuous high quality documentation, comparability of data due to the availability of a data bank, reduction in the workload of the anaesthetist and availability of additional data. Disadvantages of the electronic protocol have also been discussed in the literature. By going through the process of entering data on the course of the anaesthetic procedure on the protocol sheet, the information is mentally absorbed and evaluated by the anaesthetist. This information may, however, be lost when the data are recorded fully automatically-without active involvement on the part of the anaesthetist. Recent publications state that by using intelligent alarms and/or integrated displays manual record keeping is no longer necessary for anaesthesia vigilance. The technical design of automated anaesthesia records depends on an integration of network technology into the hospital. It will be appropriate to connect the systems to the internet, but safety requirements have to be followed strictly. Concerning the database, client server architecture as well as language standards like SQL should be used. Object oriented databases will be available in the near future. Another future goal of automated anaesthesia record systems will be using knowledge based technologies within these systems. Drug interactions, disease related anaesthetic techniques and other information sources can be integrated. At this time, almost none of the commercially available systems has matured to a point where their purchase can be recommended without reservation. There is still a lack of standards for the subsequent exchange of data and a solution to a number of ergonomic problems still remains to be found. Nevertheless, electronic anaesthesia protocols will be required in the near future. The advantages of accurate documentation and quality control in the presence of careful planning outweight cost considerations by far.

Anesthesia↗
PubMed1997

Respiratory mechanics, gastric insufflation pressure, and air leakage of the laryngeal mask airway.

A potential risk of the laryngeal mask airway (LMA) is incomplete mask seal, which causes air leakage or insufflation of air into the stomach. The objective of the present study was to assess respiratory mechanics, quantify air leakage, and measure gastric air insufflation in patients ventilated via the LMA. Thirty patients were studied after induction of anesthesia but prior to any surgical manipulations. After the insertion of the LMA, patients were ventilated with increasing tidal volumes until one of the three following end points were reached: 1) gastric air insufflation, 2) airway pressure > 40 cm H2O, or 3) limitation of further increase in tidal volume by air leakage. The following variables were determined:inspired volume (VI), expired volume (VE), maximum inspiratory pressure (Pmax), airway pressure at gastric inflation (Pinfl), respiratory time constant (RC), compliance (C), resistance (R), and leakage fraction (FL). Respiratory mechanics were in the physiological range. Gastric insufflation occurred in 27% of the patients at inspiratory pressures between 19 and 33 cm H2O. Air leakage of more than 10% was evident at inspiratory pressures between 25 and 34 cm H2O. The end point of 40 cm H2O airway pressure was reached in only three patients. We conclude that the LMA is not better in preventing airway pressure transmission to the esophagus than a conventional face mask. However, a high FL is associated with reduced gastric air insufflation.

Adolescent↗
PubMed1996

[Anesthesia in endovascular treatment of aortic aneurysm. Results and perioperative risks].

UNLABELLED: Surgical treatment of aortic aneurysms carries significant cardiovascular risks. Transvascular insertion of endoluminal prostheses is a new, minimally invasive treatment for aortic aneurysms. The pathophysiology of this novel procedure, risks and benefits of different anaesthetic techniques, and typical complications need to be defined. METHODS: With their informed, written consent, 19 male patients aged 48-83 years of ASA physical status III and IV with infrarenal (n = 18) or thoracic (n = 1) aortic aneurysms underwent 23 stenting procedures under general endotracheal (n = 9), epidural (n = 8), or local anaesthesia with sedation (n = 6). Intra-anaesthetic haemodynamics, indicators of postoperative (p.o.) oxygenation and systemic inflammatory response, and perioperative complications were analysed retrospectively and compared between anaesthetic regimens. RESULTS: Groups were well matched with regard to morphometry and preoperative risk profiles (Table I). The use of pulmonary artery pressure monitoring, incidence of intraoperative hypotensive episodes, and p.o. intensive care was more frequent with general anaesthesia. Groups did not differ in total duration of anaesthesia care, incidence and duration of intraoperative hypertensive, brady-, or tachycardic periods, incidence of arterial oxygen desaturation, use of vasopressors, colloid volume replacements, or antihypertensives (Table 2). Postoperatively, all groups showed a similar, significant systemic inflammatory response, i.e., rapidly spiking temperature (p.o. evening: mean peak 38.5 +/- 1.0 degrees C). leucocytosis, and rise of acute-phase proteins without bacteraernia (Table 3). During this period, despite supplemental oxygen, pulse oximetry revealed temporary arterial desaturation in 13 of 18 patients (70%) (Table 3). In 3 patients, hyperpyrexia was associated with intermittent tachyarrhythmias (n = 3) and angina pectoris (n = 1). There was no conversion to open aortic surgery, perioperative myocardial infarction, or death. CONCLUSIONS: Regional and local anaesthesia with sedation are feasible alternatives to general endotracheal anaesthesia for minimally invasive treatment of aortic aneurysms by endovascular stenting. However, invasive monitoring and close postoperative monitoring are strongly recommended with either method. Specific perioperative risks in patients with limited cardiovascular or pulmonary reserve are introduced by the abacterial systemic inflammatory response to aortic stent implantation. Hyperpyrexia increases myocardial and whole-body oxygen consumption, and can precipitate tachyarrhythmias. Hyperfibrino-genaemia may increase the risk of postoperative arterial and venous thromboses. Close monitoring of vital parameters and prophylactic measures, including oxygen supplementation, low-dose anticoagulation, antipyretics, and fluid replacement are warranted until this syndrome resolves.

Aged↗
PubMed1996

[The effect of preischemic blood sugar concentration on hemodynamics and regional organ blood flow during and following cardiopulmonary resuscitation (CPR) in swine].

UNLABELLED: Blood glucose alterations prior to cerebral ischaemia are associated with poor neurologic outcome, possibly due to extensive lactic acidosis or energy failure. Cerebral effects of hyper- or hypoglycaemia during cardiopulmonary resuscitation (CPR) are less well known. In addition, little information is available concerning cardiac effects of blood glucose alterations. The aim of this study was to evaluate the effects of pre-cardiac-arrest hypo- or hyper-glycaemia compared to normoglycaemia upon haemodynamics, cerebral blood flow (CBF) and metabolism (CMRO2), and regional cardiac blood flow during CPR subsequent to 3 min of cardiac and respiratory arrest and after restoration of spontaneous circulation. METHODS: After approval by the State Animal Investigation Committee, 29 mechanically ventilated, anaesthetised pigs were instrumented for haemodynamic monitoring and blood flow determination by the radiolabeled microsphere technique. The animals were randomly assigned to one of three groups: in group 1 (n = 9) blood glucose was not manipulated; in group II (n = 10) blood glucose was increased by slow infusion of 40% glucose to 319 +/- 13 mg/dl; in group III (n = 10) blood glucose was lowered by careful titration with insulin to 34 +/- 2 mg/dl. After 3 min of untreated ventricular fibrillation and respiratory arrest, CPR (chest compressor/ventilator (Thumper) and epinephrine infusion) was commenced and continued for 8 min. Thereafter, defibrillation was attempted, and if successful, the animals were observed for another 240 min. Cerebral perfusion pressure (CPP), CBF, CMRO2, coronary perfusion pressure (CorPP), and regional cardiac blood flow were determined at control, after 3 min of CPR, and at 10.30, and 240 min post-CPR. RESULTS: In group 1. 4/9 animals (44%) could be successfully resuscitated; in group II 4/10 (40%); and in group III 0/10 (0%). Prior to cardiac arrest, mean arterial pressure, CPP, and CorPP in group III were significantly lower compared to groups I and II. In group I. CPP during CPR was 26 +/- 6 mmHg; CBF 31 +/- 9 ml/ min/100g CMRO2 3.8 +/- 1.2 ml/ min/100 g; CorPP 18 +/- 5 mmHg; and left ventricular (LV) flow 35 +/- 15 ml/min/100 g. In group II; CPP = 21 +/- 5; CBF 21 +/- 7; CMRO2 1.8 +/- 0.8; CorPP 16 +/- 6; and LV flow 22 +/- 9; and in group III: CPP 15 +/- 3; CBF 11 +/- 8; CMRO2 1.5 +/- 1.1; CorPP 4 +/- 2; and LV flow 19 +/- 10. During the 240-min post-resuscitation period, there were no differences in CBF, CMRO2, or LV flow between groups I and II. CONCLUSION: Hypoglycaemia prior to cardiac arrest appears to be predictive for a poor cardiac outcome, whereas hyperglycaemia does not impair resuscitability compared to normoglycaemia. In addition, hyperglycaemia did not affect LV flow, CBF, or CMRO2. However, it has to be kept in mind that haemodynamics and organ blood flow do not permit conclusions with respect to functional neurologic recovery or histopathologic damage to the brain, which is very likely to be associated with hyperglycaemia.

Anesthesia↗
PubMed1996

[Adaptive lung ventilation (AVL). Evaluation of new closed loop regulated respiration algorithm for operation in the hyperextended lateral position].

The lateral decubitus position is the standard position for nephrectomies. There is a lack of data about the effects of this extreme position upon respiratory mechanics and gas exchange. In 20 patients undergoing surgery in the nephrectomy position, we compared a new closed-loop-controlled ventilation algorithm, adaptive lung ventilation (ALV), which adapts the breathing pattern automatically, to the respiratory mechanics with conventionally controlled mandatory ventilation (CMV). The aims of our study were (1) to describe positioning effects on respiratory mechanics and gas exchange, (2) to compare ventilatory parameters selected by the ALV controller with traditional settings of CMV, and (3) to assess the individual adaptation of the ventilatory parameters by the ALV controller. The respirator used was a modified Amadeus ventilator, which is controlled by an external computer and possesses an integrated lung function analyzer. In a first set of measurements, we compared parameters of respiratory mechanics and gas exchange in the horizontal supine position and 20 min after changing to the nephrectomy position. In a second set of measurements, patients were ventilated with ALV and CMV using a randomized crossover design. The CMV settings were a tidal volume of 10 ml/kg body weight, a respiratory rate of 10 breaths/min, an I:E ratio of 1:1.5, and an end-inspiratory pause of 30% of inspiratory time. With both ventilation modes F1O2 was set to 0.5 and PEEP to 3 cm H2O. During ALV a desired alveolar ventilation of 70 ml/ kg KG.min was preset. All other ventilatory parameters were determined by the ALV controller according to the instantaneously measured respiratory parameters. Positioning induced a reduction of compliance from 61.6 to 47.9 ml/cm H2O; the respiratory time constant shortened from 1.2 to 1.08 s, whereas physiological dead space increased from 158.9 to 207.5 ml. On average, the ventilatory parameters selected by the ALV controller resembled very closely those used with CMV. However, an adaptation to individual respiratory mechanics was clearly evident with ALV. In conclusion, we found that the effects of positioning for nephrectomy are minor and may give rise to problems only in patients with restrictive lung disease. The novel ALV controller automatically selects ventilatory parameters that are clinically sound and are better adapted to the respiratory mechanics of ventilated patients than the standardized settings of CMV are.

Adult↗
PubMed1996

[Combination of intravenous patient-controlled analgesia with epidural anesthesia for postoperative pain therapy].

The aim of this study was to prove the hypothesis that a combination of epidural anaesthesia with intravenous patient-controlled analgesia (PCA) could improve perioperative pain management. Patients of the urological department undergoing lower abdominal surgery were randomized for two different pain managements. Patients of group 1 (n = 37) were narcotized, intubated and ventilated for the operation; arriving at the recovery room, they were given a PCA-pump, the drug used was piritramide and the parameters were bolus 2.5 mg, blocking time 20 minutes and no basal infusion rate. In group 2 (n = 37) an epidural catheter was inserted preoperatively followed by narcosis with intubation and ventilation. Additionally, epidural anaesthesia was performed intraoperatively using bupivacaine 0.5%. For postoperative pain management, patients of group 2 were also given a PCA-pump (same parameters as mentioned above) and a continuous epidural infusion was started additionally (bupivacaine 0.1875%, infusion rate 8 ml/h). Patients were monitored at the urological ICU for 36 hours. Assessment of pain (6-degree scale), grade of sedation (4-degree scale), cumulative doses of piritramide, heart rate, blood pressure, respiratory rate, in group 2 additional motoric function (Bromage) and degree of epidural anaesthesia were recorded at fixed time intervals: 0, 1, 2, 3, 5, 8, 11, 15, 19, 24, 28, 32, 36 hours. There was no difference regarding age of patients or type of operation. Assessment of pain showed a significant pain reduction in group 2 compared to group 1 during the first 8 hours. This result was underlined by a significantly smaller dose of piritramide. All other parameters showed no differences except lower blood pressure and heart rate in group 2 for the first three hours. The benefits of better pain management contrast with the risks resulting from combining the two techniques. In our patients we found an improvement of pain management in the early postoperative period. The combination of epidural anaesthesia with intravenous patient-controlled analgesia can be regarded as a further possibility for treating postoperative pain in the sense of "balanced pain management".

Adult↗
PubMed1995

Automated anaesthesia record systems, observations on future trends of development.

The introduction of electronic anaesthesia documentation systems was attempted as early as in 1979, although their efficient application has become reality only in the past few years. Today, documentation technology is offered by most of the monitor manufacturers and new systems are being developed by various working groups. The advantages of the electronic protocol are apparent: Continuous high quality documentation, comparability of data due to the availability of a anaesthesia data bank, reduction of the workload of the anaesthesia staff and availability of new additional information. Disadvantages of the electronic protocol have also been discussed. Typically, by going through the process of entering data on the course of the anaesthetic procedure on the protocol sheet, the information is mentally absorbed and evaluated by the anaesthetist. This mental processing of information may, however, be missing when the data are recorded fully automatically--without active involvement on the part of the anaesthetist. It seems that electronic anaesthesia protocols will be required in the near future. The advantages of accurate documentation and quality control in the presence of careful planning will outweight cost considerations. However, at this time, almost none of the commercially available systems have matured to a point where their purchase can be recommended without reservation. There is still a lack of standards for the subsequent exchange of data and a solution to a number of ergonomic problems still remains to be found.

Anesthesia↗