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Biomedical subjects

H Forst

Publications and source records attributed to H Forst.

At least 73 records · Page 4Linked to original sources
PubMed1991

[Pathophysiologic and therapeutic aspects of the adult respiratory distress syndrome (ARDS)].

Since the first characterization of the adult respiratory distress syndrome (ARDS), knowledge of its aetiology and pathogenesis has grown considerably. In spite of this, mortality remains up to 50 to 90%, particularly if multiple organ failure is present. Because no causative clinical therapy is available up to now, significant attention is given to preventive measures like early operative stabilisation of long bone fractures, or prophylaxis of nosocomial infections. After clinical manifestation of ARDS, treatment focuses on functional disturbances of the cardiopulmonary system and on the underlying disease. The aim of this symptomatic therapy is to ensure oxygen supply according to the organisms demand. It is still unknown, however, whether the mortality of patients with ARDS can be reduced by optimising the oxygen supply. In general, oxygen supply can be enhanced by improving pulmonary gas exchange, cardiac output and blood oxygen transport capacity. For practical use the therapy often ends up with a therapeutical dilemma: On one hand, the improvement of the pulmonary gas exchange by application of PEEP can be associated with a critical decline in cardiac output, particularly if the afterload of the right ventricle is elevated. On the other hand, to increase cardiac output, both volume replacement and vasodilators can severely affect pulmonary gas exchange if the alveolo-capillary permeability is increased and pulmonary hypoxic vasoconstriction is disturbed. Thus, oxygen supply can be optimised only via invasive monitoring of the cardiorespiratory system. Although still experimental, the most promising approaches seem to be pharmacological interventions directed at suppressing the formation and effects of various humoral and cellular mediators. An improved understanding of the inflammatory processes might provide new insights in the pathophysiology of ARDS and the related therapeutic interventions.

Humans↗
PubMed1991

[Rupture of the trachea during difficult intubation].

Serious injuries of the larynx or trachea during tracheal intubation are rare but potentially life-threatening complications. This case report describes the diagnostic procedures and therapeutic management of an intubation-induced tracheal rupture in a young female patient with a musculoskeletal disorder (rigid spine syndrome). Interdisciplinary treatment requires precise documentation of the extent of the injuries, including advanced imaging techniques. Removal of the endotracheal tube prior to accurate diagnosis can result in immediate airway obstruction. Because of the risk of infection, as a rule surgical treatment is indicated.

Adult↗
PubMed1991

[A life-threatening arrhythmia (ventricular tachycardia) triggered by a Swan-Ganz catheter in a patient with the WPW syndrome].

The induction of dysrhythmias during or after pulmonary artery catheterization is a serious complication in critically ill patients. The following case presentation reports the incidence of life-threatening ventricular tachycardia after catheterisation in a patient known to have Wolff-Parkinson-White (WPW)-Syndrome. The dysrhythmia began during repositioning of the patient 10 h after placement of the catheter. Attempted inversion by administration of Ajmalin was unsuccessful. Removal of the catheter resulted in prompt cessation of the dysrhythmia.

Adult↗
PubMed1990

Acute pulmonary microembolism induces different regional changes in preload and contraction pattern in canine right ventricle.

STUDY OBJECTIVE: The aim of the study was to investigate the influence of acute pulmonary embolism on local myocardial preload and contraction pattern in right ventricle. DESIGN: Measurements of preload and contraction pattern were made in inflow and outflow tracts of canine right ventricular free wall by sonomicrometry. Local right ventricular preload was assessed from end diastolic segment length. Contraction pattern was assessed from pressure-length loops and quantified by calculating maximal, systolic, and postsystolic shortening, and protosystolic segment elongation. Data were obtained before and after microembolization with 100 microns glass beads in combination with oleic acid. SUBJECTS: 13 foxhounds of either sex were used, weight 20.4 +/- 4.0 kg. MEASUREMENTS AND MAIN RESULTS: Pulmonary microembolization resulted in a rise in systolic, mean, and end diastolic right ventricular pressure and pulmonary vascular resistance. At the same time, the pressure-length loops, originally triangular or oval, became rectangular in both inflow and outflow tract. Normalised end diastolic segment length increased in the inflow tract from 10.0 to 10.3 mm (p less than 0.01), but simultaneously decreased in the outflow tract, from 10.0 to 9.6 mm (p less than 0.05). Segment shortening in the inflow tract was not affected but deteriorated in the outflow tract from 11.6 to 2.7% (p less than 0.01). CONCLUSIONS: Increase in afterload due to pulmonary microembolization caused regionally different changes in local preload and segment shortening in right ventricular free wall. Clinically available measures of global right ventricular preload do not assess these local differences in preload and therefore may fail to reflect the functional state of the right ventricle accurately.

Animals↗
PubMed1990

Local and global function of the right ventricle in a canine model of pulmonary microembolism and oleic acid edema: influence of ventilation with PEEP.

Right ventricular (RV) dysfunction may occur due to increased RV afterload and, hence, might also contribute to the decrease in cardiac output following institution of PEEP in patients with adult respiratory distress syndrome (ARDS). To test this hypothesis, the authors examined the influence of PEEP on local and global RV function in 12 anesthetized dogs with experimental ARDS (eARDS) induced by pulmonary microembolization with glass beads and oleic acid. Local RV function was analyzed in the RV inflow tract (RVIT) and RV outflow tract (RVOT) by assessing both diastolic segment length, systolic segment shortening, and segment work (sonomicrometry). Global RV contractility was quantified by measuring maximum rate of pressure rise (dRVP/dtmax) and maximum velocity of contractile element shortening (Vmax). In eARDS, despite a fivefold increase in pulmonary vascular resistance, there was no change in cardiac index (CI), global RV contractility, RVIT and RVOT work, and RVIT shortening, whereas RVOT shortening decreased from 12.4 to 7.4% (P less than 0.01). Diastolic segment length increased in RVIT (P less than 0.05) but not in RVOT. PEEP of 10 cmH2O did not alter global RV contractility, RVIT and RVOT shortening, and RVIT work but reduced RVOT work (-35%; P less than 0.01) and CI (-11%; P less than 0.001). Cardiac index further decreased during PEEP of 20 cmH2O (-38%; P less than 0.001), while global RV contractility remained intact despite decreased RVIT and RVOT shortening (-32% and -69%; P less than 0.05) and work (-26% and -59%; P less than 0.01) in the presence of reduced fiber preload in both regions. From these findings, it was concluded that 1) the decreased CI during mechanical ventilation with PEEP at constant right ventricular end-diastolic pressure (RVEDP) is not caused by depressed global RV contractility in dogs with eARDS and a normal myocardium prior to insult. Decreased diastolic segment length and segment shortening during PEEP suggest that 2) PEEP reduces stroke volume by the Starling mechanism rather than by ischemia of the RV free wall. Finally, regionally incongruent changes of fiber preload indicate that 3) local differences in RV wall compliance are likely to occur subsequent to eARDS and PEEP.

Animals↗
PubMed1989

A new experimental model of ARDS and pulmonary hypertension in the dog.

The aim of this study was to establish a stable and reproducible model of pulmonary artery hypertension with concomitant ARDS-like changes of lung function and lung morphology. In eight anesthetized and ventilated dogs, 0.01 ml/kg oleic acid (OA) was given i.v. followed by repetitive injections of 100 microns glass beads (GB) into the right atrium until a mean pulmonary artery pressure of 35-40 mmHg was reached. Mean right ventricular (RVP) and pulmonary artery (PAP) pressures, pulmonary vascular resistance (PVR), lung compliance and resistance, PaO2, intrapulmonary shunt and colloidosmotic pressure (COP) were closely monitored for 150 min. PAP, RVP, and PVR considerably increased subsequent to OA/GB injection, and stabilized at a high level within 70 min, showing only a minimal decrease (PAP, RVP) or no change (PVR) during the following 80 min. A significant decrease of PaO2 and pulmonary compliance as well as an increase of resistance and intrapulmonary shunt were found as early as 30 min after the last embolization and they remained unchanged for 120 min. Reduction of COP suggested transcapillary leakage of macromolecules. Histology revealed an interstitial and intraalveolar edema. We conclude that the combined injection of oleic acid and glass beads provokes microvascular lung injury and results in stable pulmonary artery hypertension with concomitant ARDS-like changes of lung function. Thus, an acute model is provided in the dog allowing for the study of cardiac function in ARDS complicated by pulmonary artery hypertension.

Animals↗
PubMed1989

[Percutaneous cholecystostomy in treating acute cholecystitis in patients at risk].

Percutaneous cholecystostomy was performed in 17 poor surgical risk patients. 16 patients developed acute acalculous cholecystitis postoperatively in the intensive care unit, 1 patient had an acute cholecystitis with calculi. Diagnostic imaging using CT and US was specific for acute cholecystitis in 58% only. Percutaneous cholecystostomy was the definitive treatment in 69% of the patients. Additional cholecystectomy was required in 3 patients with complicated cholecystitis, in 1 patient with bile leakage after catheter dislocation and in 1 patient with gallbladder calculi. 3 patients died, 2 of them from reasons unrelated to the gallbladder disease. Radiology-guided percutaneous cholecystostomy performed by a transhepatic approach is a safe and effective procedure for acute cholecystitis in high-risk patients.

Acute Disease↗
PubMed1989

[Pulmonary complications within the scope of multiple organ failure].

The adult respiratory distress syndrome (ARDS) is the pulmonary manifestation of multiple organ failure. Respiratory distress, alveolar consolidation and hypoxemia refractory to oxygen are the result of uniform and unspecific morphological reactions of the alveolo capillary membrane. The development of ARDS is most commonly associated with risk factors such as sepsis, trauma, shock or pneumonia. A causal therapy for ARDS is not known. Treatment of the underlying disease, maintenance of arterial oxygenation and prevention of secondary complications are the most important therapeutic measures.

Combined Modality Therapy↗
PubMed1989

[Effect of inhalation anesthetics on the myocardium].

A review of the myocardial effects of the volatile anesthetics halothane (HAL), enflurane (ENF) and isoflurane (ISO) is presented. In the first part the effects on cardiac rhythm, myocardial contractility and oxygen supply are discussed. In the second part the pathophysiology of myocardial ischemia during anesthesia and surgery is summarized. Finally the role of inhalation anesthetics in inducing or preventing myocardial ischemia is considered, with special regard to the "coronary steal" phenomenon.

Anesthesia, Inhalation↗
PubMed1989

Lung tissue concentrations of ciprofloxacin following intravenous administration in patients.

Serum and corresponding lung tissue concentrations of ciprofloxacin (Ciprobay) were investigated in 25 patients undergoing open lung surgery for pulmonary malignancies. Drug levels were measured at various times (50-240 min) after completion of a single i.v. dose of 200 mg by bioassay and HPLC. Lung tissue concentrations peaked within one hour after dosing (bioassay: 3.2 micrograms/g, HPLC: 4.5 micrograms/g). Tissue levels exceeded corresponding serum level 3- to 4fold throughout the observation period. The results demonstrate excellent penetration properties of this new antimicrobial compound into lung tissue. Ciprofloxacin was concentrated in the lung and thus by far exceeded known minimum inhibitory concentrations for most nosocomial respiratory pathogens.

Adult↗
PubMed1988

[Local and global contractility of the right ventricle in ischemia of the free ventricular wall. An animal experiment study].

UNLABELLED: Impaired right ventricular (RV) performance due to increased RV afterload in patients with sepsis or acute respiratory failure has been attributed to relative hypoperfusion and myocardial ischemia of the stressed free RV wall. There is evidence from experiments, however, that the normal RV is able to respond to a pressure load with adequate increases in myocardial blood flow. Whether or not ischemia of the free wall contributes to RV failure and whether restoration of RV perfusion can improve RV performance remains to be elucidated. The aim of this study was to compare local RV contractility to parameters of global RV contractility prior to and after induction of ischemia to its free wall. METHODS: Studies were performed in a total of 16 open-chest dogs using sonomicrometry to determine local contractility (velocity and percentage of fiber shortening) in the RV inflow tract (n = 8) prior to, 5, and 30 min after acute ligation of the right coronary artery (RCA). Parameters of global RV contractility (dP/dtmax, Vmax) were derived from intraventricular pressure measurements (tip-manometer). Regional myocardial blood flow (n = 6) was determined by the radioactive microsphere technique. Furthermore, the septal-lateral diameters of the RV (n = 8) and left ventricle (LV, n = 5), as well as the anterior-posterior diameter (n = 4) of the LV were measured simultaneously by use of sonomicrometers (Fig. 1); ventricular pressure-diameter diagrams were constructed in order to assess the dynamic geometry of the heart. RESULTS: Acute ligation of the RCA resulted in a reduction of myocardial blood flow (-39% to -72%), predominantly in the RV inflow tract (Table 1). The segment length of the RV free wall and diameter of the RV increased following RCA ligation (Fig. 3a) whereas the septal-lateral diameter of the LV decreased concomitantly. The LV anterior-posterior diameter remained unaffected (Table 2, Fig. 3b). While local RV contractility (percent shortening and velocity of fiber shortening) deteriorated (-40% and -32%, respectively), the parameters of global RV contractility (dP/dtmax, Vmax) remained unchanged (Fig. 4a). Heart rate, mean arterial pressure, RV systolic pressure, and LV filling pressure remained unchanged (Fig. 4b), whereas RV filling pressure increased (+52%) and cardiac output was reduced (-13%).(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1987

Prevention of colonization and respiratory infections in long-term ventilated patients by local antimicrobial prophylaxis.

In a randomized clinical trial the prophylactic effects of locally administered antimicrobials on quantitative colonization and respiratory infections were studied in intubated patients with an expected period of mechanical ventilation of greater than 6 days. Nineteen patients received 50 mg of polymyxin B and 80 mg of gentamicin distributed among nose, oropharynx and stomach at 6-h intervals, as well as 300 mg of amphotericin B in the oropharynx. Twenty untreated patients served as controls. In the control group colonization by respiratory pathogens was more common (oropharynx 19 vs 6 patients (p less than 0.001); trachea 19 vs 11 (p less than 0.01)), and the number as well as the count of the colonizing species was usually higher. Fourteen patients of the control group developed respiratory infections, including nine cases of pneumonia, as compared to four patients with prophylaxis, including one case of pneumonia (p less than 0.01). Pneumonia-associated deaths were prevented with prophylaxis; however, the overall mortality remained unchanged. Respiratory infections in the prophylaxis group were associated with organisms resistant to the agents used, but the overall occurrence of resistance was not increased, as compared to the control group. We conclude that unrestrained upper airway colonization by respiratory pathogens and respiratory tract infection were causally related. Local antimicrobial prophylaxis proved to be a highly effective strategy for the prevention of potentially life-threatening pneumonias in critically ill patients, but in the present study the host setting appeared to be the major determinant of outcome.

Administration, Intranasal↗
PubMed1987

Right ventricular tissue PO2 in dogs. Effects of hemodilution and acute right coronary artery occlusion.

Right ventricular (RV) epicardial tissue oxygen pressure (PtO2) was measured polarographically by means of a platinum multiwire surface electrode on the in situ beating heart of ten anesthetized dogs prior to and after moderate (Hct 28%) normovolemic hemodilution (HD) with dextran 60. In five dogs the effect of acute occlusion of the right coronary artery (RCA) on PtO2 was analyzed. The PtO2 histograms at baseline revealed a bell-shaped configuration and a mean PtO2 of 46.2 +/- 7.1 mm Hg which coincides with the PtO2 on the left ventricle (LV) reported by others. After HD mean PtO2 increased to 51.4 +/- 8.5 mm Hg (P = 0.02) without alterations of the histogram's configuration. Hemodynamics and blood gas analyses were unchanged after HD. RCA ligature was followed by non-uniform changes in the PtO2 pattern. Thus, despite marked differences in external work and O2 consumption, the PtO2 in both RV and LV myocardium are similar at rest. The increase of PtO2 in the RV at reduced Hct values, which is not seen in the LV myocardium, can be related to differences in functional capillary density between both ventricles.

Animals↗