Biomedical subjects

K Peter

Publications and source records attributed to K Peter.

331 records · Page 19Linked to original sources

PubMedDate not supplied

Medical equipment ordinance and lack of personnel: two contrary factors influencing anesthesia patient safety.

In January 1986, West German legislators enacted the Medical Equipment Ordinance (MedGV) to define specific regulations for both manufacturers and operators of medical equipment and to offer a measure of safety to patients. We describe the history of MedGV, its regulations, and the mechanisms developed to enforce those regulations. We also evaluate its impact on clinical practice in light of the current staff shortages in anesthesia practice and research in Germany. Finally, we focus our discussion on the distinction between improved equipment as a minor factor in critical-incidents and the inadequate manpower as a major factor in anesthesia mishaps. It is unclear what will develop after 1993, when the national states in Europe form a common market.

Anesthesia↗

PubMedDate not supplied

[Autologous transfusion in scoliosis operations: preoperative autologous blood donations and intraoperative mechanical autotransfusion].

Autologous transfusion was used to reduce the high demand for blood accompanied with scoliosis surgery. Half of the blood loss could be saved by intraoperative autotransfusion (35 patients). This resulted in a corresponding reduction in homologous transfusion. An elimination of the need for homologous blood could be achieved only by the combination of preoperative blood donation and intraoperative autotransfusion (37 patients). With freezing the predeposit blood was independent of storage time and autologous plasma was available. Thus, the risks of transfusion can be avoided.

Adolescent↗

PubMedDate not supplied

Impact of the ampD gene and its product on beta-lactamase production in Enterobacter cloacae.

In an investigation of the influence of the ampD gene on beta-lactamase production and induction in Enterobacter cloacae, the ampR-ampC gene region cloned into a plasmid and the ampD gene cloned into another vector were transferred to a strain of Escherichia coli. The genetically manipulated E. coli strains served as a model for study of the inducibility of beta-lactamases in E. cloacae. In addition, beta-lactamase induction in E. cloacae bearing the previously mentioned plasmids was studied. After induction of the beta-lactamase with cefoxitin, the specific hydrolytic activity, the viable cell count, and the degradation of cefoxitin were determined. beta-Lactamase expression decreased with an increasing amount of the ampD gene product. The cefoxitin concentration decreased in proportion to the amount of enzyme, but the induction of beta-lactamase seemed not to be an important factor influencing the viable cell count of E. cloacae as long as cefoxitin concentrations exceeded the MIC. Despite different beta-lactamase concentrations, the decrease in the viable cell count was nearly identical in all experiments.

Cefoxitin↗

PubMedDate not supplied

Ischemic preconditioning attenuates portal venous plasma concentrations of purines following warm liver ischemia in man.

BACKGROUND/AIMS: Degradation of adenine nucleotides to adenosine has been suggested to play a critical role in ischemic preconditioning (IPC). Thus, we questioned in patients undergoing partial hepatectomy whether (i) IPC will increase plasma purine catabolites and whether (ii) formation of purines in response to vascular clamping (Pringle maneuver) can be attenuated by prior IPC. METHODS: 75 patients were randomly assigned to three groups: group I underwent hepatectomy without vascular clamping; group II was subjected to the Pringle maneuver during resection, and group III was preconditioned (10 min ischemia and 10 min reperfusion) prior to the Pringle maneuver for resection. Central, portal venous and arterial plasma concentrations of adenosine, inosine, hypoxanthine and xanthine were determined by high-performance liquid chromatography. RESULTS: Duration of the Pringle maneuver did not differ between patients with or without IPC. Surgery without vascular clamping had only a minor effect on plasma purine concentrations. After IPC, plasma concentrations of purines transiently increased. After the Pringle maneuver alone, purine plasma concentrations were most increased. This strong rise in plasma purines caused by the Pringle maneuver, however, was significantly attenuated by IPC. When portal venous minus arterial concentration difference was calculated for inosine or hypoxanthine, the respective differences became positive in patients subjected to the Pringle maneuver and were completely prevented by preconditioning. CONCLUSION: These data demonstrate that (i) IPC increases formation of adenosine, and that (ii) the unwanted degradation of adenine nucleotides to purines caused by the Pringle maneuver can be attenuated by IPC. Because IPC also induces a decrease of portal venous minus arterial purine plasma concentration differences, IPC might possibly decrease disturbances in the energy metabolism in the intestine as well.

Adenosine↗

PubMedDate not supplied

Prevalence of cyclic changes in limb volume (volumotion) of male patients with knee injury and the effects of ischemia/reperfusion due to tourniquet.

During surgery of limbs tourniquet up to a maximum of 2 h is frequently applied which may cause ischemia/reperfusion injury (IRI). During this condition the presence of vasomotion may have consequences for the perfusion and nutritive state of the tissues. We used a noninvasive plethysmographic method to investigate periodic changes in limb circumference (volumotion) in healthy male patients (n = 24) undergoing surgery for knee injury. To facilitate surgery a tourniquet was applied to the thigh, which caused an IRI of the leg. Results are given as mean of all values +/- SEM. Immediately after tourniquet release (duration 57.75 +/- 5.19 min) blood lactate levels in the femoral vein increased significantly from 1.40 +/- 0.08 to 2.59 +/- 0.20 mmol/l (p < 0.001) and pH fell from 7.39 +/- 0.01 to 7.32 +/- 0.01 (p < 0.001). Preoperatively 10 out of 24 patients (42%) showed signs of volumotion on the injured leg with a periodicity ranging from 0.8 to 6.9 cycles/min, whereas none showed volumotion in the control leg (p < 0.001). In the second measurement, taken after surgery and reperfusion while peripheral sympathetic nerves were blocked, 7 out of 18 patients (39%) showed volumotion on the injured leg and 0 on the control leg (p < 0.004). 6 h after IRI, volumotion was observed in 11 out of 17 patients (65%) on the injured leg and in 1 patient (6%) on the control leg (p < 0.001). The mean volume change in the patients with volumotion on the injured leg was 0.057 +/- 0.007 ml/100 ml tissues.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMedDate not supplied

Cardiovascular monitoring of elective aortic aneurysm repair using methods of chaos analysis.

INTRODUCTION: Biological signals like arterial blood pressure (ABP) and electrocardiograms are usually displayed in a linear fashion. The often very complex structure may, however, be better described by phase space plots and time-delayed vectors, enabling an advantageous display of the dynamics contained in the signal. The potentials of such a display were investigated during elective aortic aneurysm repair, where profound haemodynamic changes frequently occur. METHOD: The peripheral volume pulse was recorded at a digit using noninvasive near infrared photoplethysmography (NIRP). All patients (n = 20, mean age 72.8 years) were invasively monitored using arterial and Swan Ganz catheters. The ABP signal was continuously recorded with a computer (sample rate 128 Hz). Two different phase space plots, [x(t), y(t + 8/128 s) and x(t), d(x(t + 8/128 s) - x(t))/dt] were calculated for the NIRP and the ABP signals and continuously displayed. The stability was subjectively assessed and the fractal dimension calculated using the 'Hausdorff dimension'. The correlation between stability, fractal dimension and frequently used parameters of patient monitoring were investigated. RESULTS: All patients included in the study had an uncomplicated operation. Cardiac index (CI) and oxygen delivery (DO2) increased, and systemic vascular resistance (SVR) decreased following declamping of the aorta. The ABP signal was generally more stable. After declamping of the aorta, 14 of 16 NIRP signals became unstable, and 9 of 14 ABP signals destabilised. The time required for stabilisation of the signal varied between the individual patients. Thirty minutes after declamping, 11 of 12 ABP signals were stable, whereas 3 out of 9 NIRP signals still revealed an unstable pattern. A fractal dimension was calculated by box counting, which revealed a linear regression over two orders of magnitude in a log-log plot (Hausdorff dimension between 1.19 and 1.71). The mean fractal dimension for NIRP was significantly higher than that of the ABP signal. On clamping and declamping of the aorta, a trend to a higher fractal dimension (p = 0.08) was observed for both signals analysed. No correlation was observed between the fractal dimension and ABP, SVR index, CI, DO2 index and oxygen consumption. DISCUSSION: The dynamic changes of the signals were emphasised when they were displayed as phase space plots calculated by time-delayed vectors. The time series of the signal revealed a fractal dimension, and the observed increase at the critical time points of the operation, where the need for cardiovascular regulation is most pronounced, support the contention that a physiological system based on non-linear behaviour may enable a rapid response to haemodynamic challenges. An on-line display of phase space plots calculated by time-delayed vectors may in future provide a valuable method of monitoring for high-risk patients.

Aged↗

PubMedDate not supplied

Polyunsaturated phosphatidyl-choline and interferon alpha for treatment of chronic hepatitis B and C: a multi-center, randomized, double-blind, placebo-controlled trial. Leich Study Group.

BACKGROUND/AIMS: Polyunsaturated phospatidyl-choline (PPC) has been shown to reduce serum aminotransferases in experimental hepatitis. This multi-center, randomized, double-blind, placebo-controlled trial evaluated the effects of PPC in patients with chronic hepatitis B and C in combination with interferon alpha 2a or 2b. The diagnosis of chronic viral hepatitis was based on an abnormal serum alanine aminotransferase (ALT) value (more than twice the upper value of normal), viral replication and chronic hepatitis found on liver biopsy. METHODOLOGY: Patients received 5 million I.U. (Hepatitis B) and 3 million I.U. (hepatitis C) interferon s.c. thrice weekly for 24 weeks, respectively, and were randomly assigned to additional oral medication with either 6 capsules of PPC (total daily dose: 1.8 g) or 6 capsules of placebo per day for 24 weeks. Biochemical response to therapy was defined as a reduction of ALT by more than 50% of pre-treatment values. The responders were treated for further 24 weeks after cessation of interferon therapy with either PPC or placebo. RESULTS: 176 patients completed the study protocol (per-protocol population: 92 in the PPC and 84 in the placebo group). A biochemical response (> 50% ALT reduction) was seen in 71% of patients who were treated with PPC, but only in 56% of patients who received placebo (p < 0.05). PPC increased the response rate in particular in patients with hepatitis C: 71% of those patients responded in the PPC group versus 51% in the placebo group (p < 0.05). Prolonged PPC therapy given to responders beyond the cessation of interferon therapy tended to increase the rate of sustained responders at week 48 in patients with hepatitis C (41% versus 15% in the control group; p = 0.064). In contrast, PPC did not alter the biochemical response to interferon in patients with hepatitis B. PPC did not accelerate elimination of HBV-DNA, HBeAg and HCV-RNA. CONCLUSIONS: In conclusion, PPC may be recommended in patients with chronic hepatitis C in combination with interferon and after termination of interferon in order to reduce the high relapse rate. PPC may not be recommended for patients with chronic hepatitis B. In contrast to IFN and other antiviral agents PPC does not carry major risks and is tolerated very well.

Adult↗