[Prophylactic ventilation of severely injured patients with thoracic trauma--does it always make sense?]. / Prophylaktische Beatmung des Schwerverletzten mit Thoraxtrauma--immer sinnvoll?

For therapy of blunt thoracic trauma in multiple injured patients, some studies have recommended prophylactic ventilation with kinetic therapy for 3-5 days. In contrast other clinics prefer to reduce the time of ventilation and to extubate as soon as possible. In this retrospective study our patient collective was investigated to find out if early extubation is linked to a higher complication rate. A total of 26 ventilated patients with severe thoracic trauma and an abbreviated injury scale score (AIS thorax) >3 were included in the study. The mean time of ventilation was 98.4 h and in patients without head injury 71.3 h. Out of 22 patients 4 had to be reintubated which had to be repeated for 2 patients. Of the patients 3 developed pneumonia but no cases of adult respiratory distress syndrome (ARDS) were observed. Of the patients 4 died due to other injuries. The mean stay on the intensive care unit was 6.3 days and the mean stay in hospital 22.6 days. Our findings indicate that even with early and aggressive weaning from a respirator with extensive lung contusions an adequate therapy of thorax trauma is possible without having a higher incidence of complications.

[Stress-associated hypertension in the work place: results of the STARLET project]. / Stressassoziierte Hypertonie am Arbeitsplatz--Ergebnisse des STARLET-Projekts.

BACKGROUND AND OBJECTIVE: To assess the influence of work stress and initial blood pressure on the prognosis of hypertension. SUBJECTS AND METHODS: In a prospective, controlled, multicentre, observational study, ambulatory 24-hour blood pressure measurements (ABPM) of employees from different work places were recorded at the work place on working days. Recurrent ABPM were performed for up to 5 years on 3448 subjects (mean age 44.6 years) who gave consent for follow-up. Subjects with hypertension were told to consult their family doctor so that they could receive antihypertensive treatment (the angiotensin receptor blocker eprosartan, an ACE-inhibitor or a beta-blocker were recommended for initial treatment). Subjects were classified as being in mental strain (stress-positive [stress+]/ stress-negative [stress-]), using standardized questionnaires. RESULTS: Only 1242 (36.0%) of the 3448 employees (69.% males) were normotensives. Only 166 (7.5%) of the 2206 hypertensives had normal ABPMs (<135/85 mmHg) and received antihypertensive treatment at the time of inclusion into the trial. During follow-up 57.8% of patients were treated with eprosartan or ACE-inhibitors, 34.6% with beta-blockers. By the time of the final visit 80.5% of hypertensives had achieved improvement of systolic and/or diastolic blood pressures (29.1% normotensive). Patients with hypertensive ABPM at baseline had more cardiovascular events than normotensives (normotensives 3.0%; grade 1 7.8%, grade 2-3 9.8%). Hypertensive ABPMs at the last follow up or an increase in blood pressure grade were associated with higher event rates than normotensives (stable normotensives 1.8% events vs. stable hypertensives 7.9%, vs. worsening or grade 2-3: 9.1%) More hypertensives were classified as stress+ than normotensives. Persons classified as stress- (or changing to stress-) had fewer events (6.2%) than those regarded as stress+ or changing to stress+ (7.1%). Persons regarded as stable stress- had lower mean blood pressures than those who were stable stress+. Change to another stress group was associated with an increase or decrease of mean blood pressure. CONCLUSIONS: Many employed people are hypertensive at work and are not treated adequately. ABPM control and antihypertensive treatment based on eprosartan, ACE-inhibitors or beta-blockers resulted in a significant increase in the number of patients with lower blood-pressure levels and a reduction in cardiovascular events. Patients under mental strain were more likely to be hypertensive. Mental strain was associated with changes in blood pressure.

[Ketamine attenuates the contractile response to vasoconstrictors in isolated coronary artery rings]. / Ketamin hemmt die Wirkung von Vasokonstriktoren an isolierten Koronararterien.

OBJECTIVE: Ketamine was shown to increase coronary blood flow. It was the aim of this study to answer the question whether ketamine directly dilates coronary arteries. METHODS: Using the model of isolated vessel rings we studied the effects of ketamine (2.5, 25, and 250 microg ml(-1)) on the contractile response to three vasoconstrictors, acetylcholine, histamine, and serotonin in porcine coronary artery segments. Other rings were contracted with KCl or PGF (2a) and then treated with ketamine (5 up to 500 microg ml(-1) added cumulatively). RESULTS: Ketamine dose-dependently dilated coronary arteries in concentrations beyond those used in clinical practice. In intact rings ketamine racemate (250 microg ml(-1)) attenuated contractions mediated by acetylcholine by 38.8 +/- 2.8%, histamine by 33.0 +/- 4.4% and serotonin by 42.1 +/- 3.7% (p < 0.05). There were no differences between intact and denuded rings (acetylcholine 38.5 +/- 2.8%, histamine 26.6 +/- 4.7%, serotonin 30.0 +/- 3.2%). With low concentrations of ketamine (2.5 microg ml(-1)) a slight tendency towards a contraction was recorded (n. s.). In rings precontracted with either KCl or PGF (2a) ketamine caused a small enhancement of contraction (KCl: 101.4 +/- 0.4%, PGF (2a): 101.3 +/- 1.4%) when administered in low concentration (5 microg ml(-1)), but almost complete relaxation (KCl: 0.4 +/- 1.3%, PGF (2a): 0.0 +/- 5.4%) in high concentration (500 microg ml(-1)). CONCLUSIONS: It is concluded that ketamine dose-dependently dilates porcine coronary arteries in concentrations beyond those used in clinical practice and that this effect is independent of endothelial function.

High-dose midazolam and the attenuation of the contractile response to vasoconstrictors in coronary artery segments.

BACKGROUND AND OBJECTIVE: Benzodiazepines may cause hypotension and are reported to interfere with smooth vascular muscle activity. The aim was to elucidate the influence of three different benzodiazepines on the vascular reactivity of coronary arteries. METHODS: Using the model of isolated vessels, we studied the impact of midazolam (0.15, 1.5, 15 microg mL(-1)), diazepam (0.1, 1.0, 10 microg mL(-1)) and flunitrazepam (0.01, 0.1, 1.0 microg mL(-1)) on the contractile responses to histamine (2 x 10(-5) mol L(-1)) and serotonin (3 x 10(-5) mol L(-1)) in isolated intact and denuded coronary arteries. RESULTS: Midazolam significantly attenuated the contractile response when administered in high concentrations (15 microg mL(-1)). This effect was more pronounced in intact than in denuded preparations (histamine: -22.7 versus -7.3%, P = 0.0079; serotonin: -47.1 versus -15.9%, P < 0.0001). Diazepam and flunitrazepam exerted no significant effects on the vascular tone of coronary arteries. CONCLUSIONS: Midazolam, but not diazepam or flunitrazepam, attenuates the contractile responses to vasoconstrictors in concentrations beyond those used in clinical practice. This effect is in part mediated by endothelial factors.

Propofol and thiopental attenuate the contractile response to vasoconstrictors in human and porcine coronary artery segments.

The effects of propofol and thiopental on three vasoconstrictors, acetylcholine, histamine, and serotonin were studied in isolated porcine and human coronary artery rings. Propofol and thiopental attenuated the contractile response to all mediators in a dose-dependent manner. This dilating effect was fairly weak using low concentrations (propofol 1 microg mL-1 and 10 microg mL-1, thiopental 5 microg mL-1 and 10 microg mL-1). In the presence of high concentrations (propofol 100 microg mL-1, thiopental 50 microg mL-1) marked relaxation was observed (propofol -32% up to -49%, P < 0,05; thiopental -23% up to -67%, P < 0.05). These dilating effects were seen both in intact and denuded rings, the differences were not significant. Human coronary artery segments were relaxed by thiopental (-22% to -76%) and propofol (-11% to -67%) to a similar extent. Our data indicate that propofol and thiopental relax isolated coronary segments in a dose-dependent manner, and that there is no evidence that these effects are dependent of endothelial factors.

Development and initial in vivo testing of a new hydraulic drive system (Paedipump) for circulatory support in infants.

The main limitation in the use of circulatory support in children is the lack of an adequate system with regard to size and pumping capacity. Recently, two pneumatically driven ventricular support systems with low volume chambers for use in a pediatric population became available. We have developed a hydraulic drive system with an advantageous exact control of the stroke volume. The system enables two different modes of operation: the full-empty and the filled-empty modes. In both cases the ventricle is empty at the end of systole. This new system was tested in experimental animals (6 pigs, body weight 9.5-14.0 kg) with normal and reduced left ventricular function (MAP<45 mmHg). A 25 ml ventricle (HIA-Medos) was implanted. The full-empty and the filled-empty mode used led to a significant load reduction, both in animals with normal and impaired cardiac function. Plasma lactate levels, pH-values and total body O2-consumption were in the normal range during circulatory support indicating adequate organ perfusion. Results showed that sufficient ventricular support was achieved during all pumping modes due to the possibility of controlling and modifying the stroke volume of the hydraulically driven support system employed according to necessity. This is a promising feature for its future application in infants with congenital or acquired heart diseases.

Influence of high-dose ketamine on the vascular reactivity of human and porcine isolated coronary artery segments.

The influence of ketamine on the vasomotor effect of histamine and serotonin was studied in isolated human and porcine coronary artery rings. Ketamine (10(-3) mol L-1) attenuated the contractile response to both mediators significantly (P < 0.05 for histamine concentrations of 3 x 10(-5) mol L-1 and above as well as for serotonin concentrations of 3 x 10(-8) mol L-1 and above). This effect of ketamine was observed in intact and endothelial denuded porcine rings (difference n.s.) as well as in coronary arteries from explanted human hearts of patients undergoing heart transplantation. It is concluded that this reduction of the contractile response to histamine and serotonin caused by ketamine is not dependent on the endothelial function (e.g. endothelium-derived relaxing factor).