PubMed Health⌕ Search

Biomedical subjects

H van Aken

Publications and source records attributed to H van Aken.

At least 19 recordsLinked to original sources
PubMed2006

[Role of ketamine in sepsis and systemic inflammatory response syndrome].

Ketamine is the only intravenous anesthetic that causes an increase in mean arterial pressure without compromising cardiac output. These beneficial effects are basically linked to stimulation of the sympathetic nervous system, inhibition of adenosine triphosphate-sensitive potassium channels and interactions with the nitric oxide pathway. Experimental and clinical studies have shown that ketamine exerts antiinflammatory properties by inhibiting the release of proinflammatory cytokines, such as tumor necrosis factor-alpha and interleukin-6. In addition, there is increasing evidence that early ketamine administration reduces mortality in experimental sepsis models. In view of the current literature ketamine appears to represent a beneficial therapeutic option for long-term sedation of patients with arterial hypotension resulting from sepsis and systemic inflammatory response syndrome (SIRS). However, it has to be taken into account that ketamine inhibits endothelial nitric oxide synthase, thereby potentially aggravating impaired (micro) regional blood flow in sepsis. Future studies are required to investigate the role of ketamine in the treatment of patients with sepsis and SIRS.

Adenosine Triphosphate↗
PubMed2005

[Intestinal malperfusion in critical care patients].

Due to the bowel's poor tolerance of hypoxia, intestinal malperfusion presents as a grave disease with high mortality. The intensivist is confronted with this condition in association with other underlying diseases, in the course of surgery, during application of medication or associated with invasive therapy. In a critical care setting, the non-occlusive mesenteric ischemia (NOMI) is of increasing importance. Since critical care patients often lack clinical symptoms, special attention is required and one main factor of the patient's prognosis is early diagnosis. This review summarizes pathophysiology and diagnostic aspects and the range of therapeutic and preventive measures.

Blood Transfusion↗
PubMed2005

[Vasopressin and terlipressin in sepsis and systemic inflammatory response syndrome. Effects on microcirculation, oxygen transport, metabolism and organ function].

Vasopressin and terlipressin are increasingly used as alternative non-adrenergic vasopressors for hemodynamic support of septic patients with arterial hypotension. Despite excellent vasopressive effects, vasopressin analogues may potentially impair macro-hemodynamics, oxygen transport and microvascular blood flow. Due to those unwanted side-effects, vasopressin and terlipressin may potentially compromise organ function and possibly foster the development of multiple organ failure. This review article discusses the results of clinical and experimental studies to judge the effects of vasopressin and terlipressin on microcirculation, oxygen supply, metabolism and organ function in patients with sepsis or systemic inflammatory response syndrome (SIRS). Although vasopressin analogues are emerging as promising alternatives to treat catecholamine-refractory hypotension, there is no evidence that vasopressin receptor agonists improve outcome. To date, vasopressin and terlipressin can, therefore, not be recommended for routine clinical use.

Animals↗
PubMed2005

[Corrective osteotomy of the humerus using perivascular axillary anesthesia according to Weber in a patient suffering from McCune-Albright syndrome].

We report on a 20-year-old patient with McCune-Albright syndrome suffering from global respiratory insufficiency who required continuous mask ventilation and where intubation had to be avoided. Perivascular axillary anesthesia according to Weber was performed for a double corrective osteotomy of the humerus. During plexus anesthesia the patient was positioned on the non-anesthesized side in a 15 degrees Trendelenburg position. An extension of analgesia was observed up to the complete upper arm region. Using the modified positioning an extension of brachial plexus anesthesia is possible.

Adult↗
PubMed2005

Recombinant human antithrombin III restores heparin responsiveness and decreases activation of coagulation in heparin-resistant patients during cardiopulmonary bypass.

OBJECTIVES: We sought to evaluate the efficacy of recombinant human antithrombin III for restoration of heparin responsiveness in heparin-resistant patients scheduled for cardiac surgery. METHODS: This was a multicenter, randomized, double-blind, placebo-controlled study in heparin-resistant patients undergoing elective cardiac surgery. Patients were considered heparin resistant if the activated clotting time was less than 480 seconds after 400 U/kg heparin. Fifty-two heparin-resistant patients were randomized into 2 cohorts. One cohort received a single bolus (75 U/kg) of recombinant human antithrombin III (n = 28), and the other, the placebo group (n = 24), received a normal saline bolus. If the activated clotting time remained less than 480 seconds, this was defined as treatment failure, and 2 units of fresh frozen plasma were transfused. Patients were monitored for adverse events during hospitalization. RESULTS: Six (21%) of the patients in the recombinant human antithrombin III group received fresh frozen plasma transfusions compared with 22 (92%) of the placebo-treated patients ( P < .001). Two units of fresh frozen plasma did not restore heparin responsiveness. There was no increased incidence of adverse events associated with recombinant human antithrombin III administration. Postoperative 24-hour chest tube bleeding was not different in the 2 groups. Surrogate measures of hemostatic activation suggested that there was less activation of the hemostatic system during cardiopulmonary bypass in the recombinant human antithrombin III group. CONCLUSION: Treatment with recombinant human antithrombin III in a dose of 75 U/kg is effective in restoring heparin responsiveness and promoting therapeutic anticoagulation for cardiopulmonary bypass in the majority of heparin-resistant patients. Two units of fresh frozen plasma were insufficient to restore heparin responsiveness. There was no apparent increase in bleeding associated with recombinant human antithrombin III.

Adult↗
PubMed2001

The inhibitory effect of bupivacaine on prostaglandin E(2) (EP(1)) receptor functioning: mechanism of action.

Prostaglandin E(2) receptors, subtype EP(1) (PGE(2)EP(1)) have been linked to several physiologic responses, such as fever, inflammation, and mechanical hyperalgesia. Local anesthetics modulate these responses, which may be due to direct interaction of local anesthetics with PGE(2)EP(1) receptor signaling. We sought to characterize the local anesthetic effects on PGE(2)EP(1) signaling and elucidate mechanisms of anesthetic action. In Xenopus laevis oocytes, recombinant expressed PGE(2)EP(1) receptors were functional (half maximal effect concentration, 2.09 +/- 0.98 x 10(-6) M). Bupivacaine, after incubation for 10 min, inhibited concentration-dependent PGE(2)EP(1) receptor functioning (half-maximal inhibitory effect concentration, 3.06 +/- 1.26 x 10(-6) M). Prolonged incubation in bupivacaine (24 h) inhibited PGE(2)-induced calcium-dependent chloride currents (I(Cl(Ca))) even more. Intracellular pathways were not significantly inhibited after 10 min of incubation in bupivacaine. But I(Cl(Ca)) activated by intracellular injection of GTPgammaS (a nonhydrolyzable guanosine triphosphate [GTP] analog that activates G proteins, irreversible because it cannot be dephosphorylated by the intrinsic GTPase activity of the alpha subunit of the G protein) was reduced after 24 h of incubation in bupivacaine, indicating a G protein-dependent effect. However, inositol 1,4,5-trisphosphate- and CaCl(2)- induced I(Cl(Ca)) were unaffected by bupivacaine at any time points tested. Therefore, bupivacaine's effect is at phospholipase C or at the G protein or the PGE(2)EP(1) receptor. All inhibitory effects were reversible. We conclude that bupivacaine inhibited PGE(2)EP(1) receptor signaling at clinically relevant concentrations. These effects could, at least in part, explain how local anesthetics affect physiologic responses such as fever, inflammation, and hyperalgesia during the perioperative period.

Anesthetics, Local↗
PubMed1999

[Concept for continuing medical education of the European Union of Medical Specialists--EUMS].

In Europe, emerging national structures of continuing medical education (CME) have to be connected in an umbrella structure of national authorities featuring the international exchange of accreditation and credits. In this umbrella structure, following topics need to be addressed: harmonization of the system of accreditation of providers of formally planned CME, the formulation of basic requirements for providers of formally planned CME, the system of quality assessment of the provided CME, and the system of awarding of CME credits to individual specialists.

Education, Medical↗
PubMed1997

[Interaction of nimodipine and propofol in dogs. Hemodynamics and cardiodynamics].

UNLABELLED: Nimodipine is frequently used for treatment of cerebral vasospasm in patients undergoing intracerebral vascular surgery and during intensive care therapy of patients with subarachnoid haemorrhage. Propofol is being increasingly used as a hypnotic drug in neuroanaesthesia and for sedation in critically ill patients. There is evidence of a propofol effect on voltage-dependent calcium channels; hence, the administration of propofol may interact with the haemodynamic effects of nimodipine. We investigated the haemodynamic interactions of both compounds in chronically instrumented dogs. METHODS: Five mongrel dogs were chronically instrumented for measurement of heart rate (HR), left atrial (LAP), aortic (ABP), and left ventricular pressure (LVP), LV dP/dt, cardiac output (CO), systemic vascular resistance (SVR), coronary blood flow velocity (CBFV), and myocardial wall-thickening fraction (WTF). After complete recovery from surgery and assessment of normal resting blood gas values and temperature, all animals received on separate days either propofol 30 mg/kg.h (P), nimodipine in two maintenance doses in the awake state (N), or the combination of nimodipine and propofol (N+P). The maintenance doses of nimodipine in N and N+P were 1 and 2 micrograms/kg.min for 40 min each after a bolus of either 10 or 20 micrograms/kg min over 2 min. Measurements were performed as controls, in the middle (20 min), and at the end (40 min) of each maintenance infusion of nimodipine or at equivalent points in time in group P (Fig. 1). Animals receiving propofol were mechanically ventilated after endotracheal intubation. Blood gas values were kept within the normal range. All data were analysed with repeated measures of ANOVA followed by student's t-test with Bonferroni correction. RESULTS: There was no statistically significant difference for any of the measured parameters between N and N+P or between the two maintenance doses of nimodipine (Table 1). HR was significantly higher with both doses of nimodipine in the awake state compared to the control values (123 +/- 7.1 and 146 +/- 6.4 vs 78 +/- 2.4/min). The administration of nimodipine with and without propofol led to a significant increase in CBFV (Fig. 2). However, there was no difference in CBFV between nimodipine in the awake state and in combination with propofol (Fig. 2). CONCLUSIONS: We conclude that administration of propofol does not alter the systemic haemodynamic and regional myocardial effects of a nimodipine infusion in a dose of 1 or 2 micrograms/kg.min in chronically instrumented dogs.

Anesthetics, Intravenous↗
PubMed1997

[Mechanical myocardial support systems 1997: an overview of inta-aortic balloon counterpulsation to implantable left ventricular support systems].

The development of cardiopulmonary bypass (CPB) to support the systemic circulation during cardiac surgical procedures became a clinical reality in 1953. Although the use of CPB for the treatment of post-infarction cardiogenic shock met with little success, intra-aortic balloon counterpulsation was used successfully in 1968 to reduce ischaemic injury in a patient with cardiogenic shock. Today, a broad spectrum of circulatory assist devices for short- and long-term application is available. Three major indication groups for the use of support devices are established. In low-cardiac-output syndrome after cardiac surgical procedures, short-term devices are utilised to enable myocardial recovery. In transplantation candidates suffering from drug-resistant pump failure, the implantation of long-term devices as a bridge to heart transplantation is indicated, and in NYHA class IV patients with contraindications to heart transplantation, the implantation of long-term devices as an alternative to transplantation is under discussion. In the literature, post-cardiotomy support survival is less than 30% on average. About 70% of mechanically bridged patients have survived to undergo heart transplantation and were transplanted with over 90% survival. Major problems during mechanical support are infection, bleeding, and thromboembolism. In view of patients' natural course without support, these clinical results are favourable.

Defibrillators, Implantable↗
PubMed1997

[The patient with respiratory problems].

Despite improvements in operative and anesthesiological techniques, respiratory problems in surgical patients have been minimized but not eliminated. In addition to risks which are typical for the individual patient, the perioperative respiratory morbidity is affected by anesthesiological manipulations as well as the operation and the nature of the operation (elective versus emergency). In this paper, after describing anesthesia-associated disturbances of the respiratory situation together with worsening due to the disease in patients with COLD, techniques and methods for therapy, prophylaxis, and prognostic assessment are delineated. Two examples are given for patients with respiratory problems (abdomino-thoracic esophageal resection as a example of local trauma in patients with numerous preoperative risk factors and acute necrotizing pancreatitis to describe the sequelae of a toxic process). The essence of our discussion is that, prognostically, preoperative diagnosis is of reduced value. Only a synopsis of clinical findings together with spirometry and blood gas analysis appears to be relevant. Early mobilization in conjunction with excellent postoperative pain therapy is of utmost importance, which is equivalent to the almost routine placement of a patient controllable epidural analgesia technique. These concepts have shown in the two patient groups described that respiratory morbidity may be reduced significantly. Cooperation between surgeons and anesthesiologists, which is characterized by complete and mutually high competence on both sides, is essential for successfully managing patients at increased respiratory risk.

Anesthesia, Epidural↗
PubMed1996

Single dose i.v. tropisetron in the prevention of postoperative nausea and vomiting after gynaecological surgery.

In a prospective, randomized, multicentre, double-blind, placebo-controlled study, we have compared the efficacy of a single i.v. dose of tropisetron 0.5 mg, 2 mg and 5 mg in the prevention of postoperative nausea and vomiting (PONV). We studied 385 ASA class I and II female patients undergoing abdominal or vaginal gynaecological surgery, including laparoscopy. Tropisetron or placebo were administered before a standardized general anaesthetic. The frequency of vomiting in the 24-h period after entry into the recovery room was reduced from 44% after placebo to 31%, 26% and 30% after tropisetron 0.5 mg, 2 mg and 5 mg, respectively (P = 0.06, P = 0.009 and P = 0.043; unadjusted). Compared with placebo, nausea was reduced from 55% to 46%, 34% and 46% (P = 0.25, P = 0.003, P = 0.22), and need for rescue treatment from 39% to 29%, 23% and 35% (P = 0.13, P = 0.017 and P = 0.59) for the same groups. Tropisetron 2 mg appeared to be the optimal dose for prophylaxis against PONV with a side-effect profile similar to that of placebo.

Adult↗
PubMed1995

Effect of an equal volume replacement with 500 mL 6% hydroxyethyl starch on the blood and plasma volume of healthy volunteers.

The effect of an equal volume replacement with 6% low molecular weight (200,000) hydroxyethyl starch (substitution ratio 0.60-0.66) (Elohaes) on the blood volume and plasma volume of eight healthy volunteers was investigated with special attention to volume overshooting. After replacement of 500 mL whole blood, blood volume was measured repeatedly for 8 1/2 h using chromium-51 labelled erythrocytes. Red cell volume and plasma volume were calculated from standard formulae. After replacement, blood and plasma volumes were unchanged from control (4754 +/- 630 mL and 2900 +/- 450 mL, respectively). The haematocrit decreased from 43.7 +/- 2.5% to 39.0 +/- 1.4% (1 h after starch infusion) and 41.1 +/- 1.9% (7.5 h after starch infusion). There were no significant changes in haemodynamic variables (systolic and diastolic blood pressure; heart rate), liver function (bilirubin; transaminases), renal function (serum creatinine; serum sodium) or coagulation (activated partial thromboplastin time). Alpha-amylase was significantly increased, which is a well known effect of starches. The replacement of 500 mL whole blood by hydroxyethyl starch maintains isovolaemia for at least 8 h in normal volunteers without any significant volume overshooting; this is not what was seen in earlier studies. This should increase safety in patients with cardiac disease.

Adult↗
PubMed1993

Light-induced photon emission by mammalian cells.

In this work, the light-induced photon emission (IPE) by suspensions of mammalian cells was examined. IPE is extremely low and for detection in a single photon counting device with a cooled EMI 9558QB photomultiplier tube was used. The mammalian cells in this study were from different tissues and different mammalian species including cat, Chinese hamster, cow, dog, human, monkey, mouse and rat. The IPE was detected in all mammalian cells tested, but was different for the various cell types, ranging from 4 to 100 photons per 10(4) cells. Although our data agree with previous studies in that the IPE of non-fibroblastic normal cells is distinct from that of malignant cells our results reveal that cells of fibroblastic origin show the highest IPE values.

3T3 Cells↗