Biomedical subjects

Johannes T A Knape

Publications and source records attributed to Johannes T A Knape.

7 recordsLinked to original sources

PubMed2006

Platelet-rich plasma preparation using three devices: implications for platelet activation and platelet growth factor release.

BACKGROUND: In this study, three commercial systems for the preparation of platelet-rich plasma (PRP) were compared and platelet growth factors release was measured. METHODS: Ten healthy volunteers donated whole blood that was fractionated by a blood cell separator, and a table-top centrifuge to prepare PRP. Furthermore, an autologous growth factor filter was used to concentrate PRP fractionated by the blood cell separator. PRP was subsequently activated with autologously produced thrombin to degranulate the platelets to measure platelet-derived growth factor-AB (PDGF-AB), transforming growth factor-beta (TGF-beta), insulin-like growth factor-1 (IGF-1), and vascular endothelial growth factor (VEGF). RESULTS: PRP contained significantly higher platelet counts compared with baseline values (p < 0.001). PDGF-AB concentrations were increased more than 18-fold in the platelet gel supernatant when the cell-separator and GPS were used, whereas only a 3-fold increase was seen with the AGF. CONCLUSION: The three PRP devices enable the preparation of PRP for the release of high concentrations of platelet growth factor, but showed different harvesting capacities for the collection of concentrated platelets. The administration of thrombin for PRP activation resulted in the release of high concentrations of PDGF-AB and TGF-beta but only when PRP had not been activated during the preparation process in vitro.

Humans↗

PubMed2006

Platelet-rich plasma and platelet gel: a review.

Strategies to reduce blood loss and transfusion of allogeneic blood products during surgical procedures are important in modern times. The most important and well-known autologous techniques are preoperative autologous predonation, hemodilution, perioperative red cell salvage, postoperative wound blood autotransfusion, and pharmacologic modulation of the hemostatic process. At present, new developments in the preparation of preoperative autologous blood component therapy by whole blood platelet-rich plasma (PRP) and platelet-poor plasma (PPP) sequestration have evolved. This technique has been proven to reduce the number of allogeneic blood transfusions during open heart surgery and orthopedic operations. Moreover, platelet gel and fibrin sealant derived from PRP and PPP mixed with thrombin, respectively, can be exogenously applied to tissues to promote wound healing, bone growth, and tissue sealing. However, to our disappointment, not many well-designed scientific studies are available, and many anecdotic stories exist, whereas questions remain to be answered. We therefore decided to study perioperative blood management in more detail with emphasis on the application and production of autologous platelet gel and the use of fibrin sealant. This review addresses a large variety of aspects relevant to platelets, platelet-rich plasma, and the application of platelet gel. In addition, an overview of recent animal and human studies is presented.

Animals↗

PubMed2004

Large-dose intrathecal sufentanil prevents the hormonal stress response during major abdominal surgery: a comparison with intravenous sufentanil in a prospective randomized trial.

We studied the effect of large-dose intrathecal sufentanil (ITS) for major abdominal surgery on the hormonal stress response. Forty patients were randomly allocated to receive either IV sufentanil (IVS) or 150 microg of ITS as part of general anesthesia. In the IVS group, adrenocorticotropic hormone (ACTH) and cortisol concentrations were larger than baseline and the ITS group, 60 min after incision and at skin closure. Plasma concentrations of cortisol and ACTH were not different from baseline in the ITS group during surgery. Six hours after skin closure, cortisol concentrations were larger than baseline in both groups. Twenty-four and 48 h after skin closure, ACTH and cortisol values were similar between groups. Norepinephrine concentrations increased after surgery in both groups. Blood glucose levels increased in both groups during and after surgery. Pain scores and morphine consumption during the first 48 h after surgery were lower in the ITS group. The data show that large-dose ITS prevents the intraoperative hormonal stress response in comparison with balanced anesthesia. We speculate that this is due to the highly specific binding of sufentanil to spinal and supraspinal receptors. This technique improves postoperative analgesia when compared with balanced anesthesia.

Abdomen↗

PubMed2003

Radiofrequency lesioning of dorsal root ganglia for chronic lumbosacral radicular pain: a randomised, double-blind, controlled trial.

BACKGROUND: Results of observational studies have shown pain reduction with percutaneous radiofrequency lesioning of dorsal root ganglia for lumbosacral radicular pain, but there are few randomised controlled trials. We aimed to assess the efficacy of radiofrequency lesioning of dorsal root ganglia for lumbosacral radicular pain. METHODS: We screened 1001 patients, who were mostly referred by their family doctor, in four hospitals for a double-blind randomised trial. 83 patients met inclusion criteria and thus were randomly assigned to receive a radiofrequency lesion or control treatment of the involved dorsal root ganglion. Control treatment was done in the same way as radiofrequency lesioning, but without radiofrequency current. Preoperatively and during 3-month follow-up, patients reported visual analogue leg-pain and back-pain scores, physical impairment, and use of analgesics in a diary. Primary outcome was success or failure of treatment, defined by a multidimensional decision rule, which included median outcome variables from the diary. Post-hoc analysis for possible covariate interference with outcome variables was done. Primary outcome data were analysed on an intention-to-treat basis. FINDINGS: 45 patients were assigned radiofrequency lesioning and 38 control treatment. Three patients dropped out before 3 months. After 3 months, seven (16%) of 44 patients treated with radiofrequency lesioning and nine (25%) of 36 in the control group had successful treatment (difference -9.1% [95% CI -33.0 to 12.0], p=0.43). No differences between groups in side-effects were seen. INTERPRETATION: Lumbosacral radiofrequency lesioning of dorsal root ganglia failed to show advantage over control treatment with local anaesthetics. Thus, its use as routine treatment in lumbosacral radicular pain should not be advocated.

Catheter Ablation↗

PubMed2002

The effect of outpatient preoperative evaluation of hospital inpatients on cancellation of surgery and length of hospital stay.

UNLABELLED: To evaluate the possible effects of outpatient preoperative evaluation (OPE) for new surgical patients who will be inpatients, we conducted an observational study at a university hospital in The Netherlands. Various outcomes before and after the introduction of an OPE clinic were compared. The study population comprised all 21,553 elective adult inpatients operated on between January 1, 1997 and December 31, 1999. Cardiac surgery, obstetric and pediatric patients, and patients operated on in same-day surgery were excluded. The main outcome measures were surgical cases canceled for medical reasons, rate of same-day admissions (who were expected to increase), and length of hospital stay. After introduction of OPE, the rate of cancellations for medical reasons decreased from 2.0% to 0.9% (adjusted odds ratio 0.7, 95% CI, 0.5--0.9). The rate of same-day admissions increased from 5.3% before to 7.7% after OPE introduction (adjusted odds ratio 1.2, 95% CI, 1.01--1.39), and the total hospital length of stay (in days) significantly decreased by a factor of 0.92 (0.90--0.94), which was partly the result of a reduction in preoperative admission time. We concluded that, although smaller than anticipated, the use of OPE for potential inpatients leads to a significant reduction of cancelled cases and of length of admission. Further increase of these benefits from OPE requires changes in institutional policy, such as forcing surgical departments to increase their number of same-day admissions. IMPLICATIONS: An observational study was conducted to compare various outcomes before and after the introduction of outpatient preoperative evaluation (OPE). Although smaller than anticipated, OPE for potential inpatients leads to a significant reduction of canceled cases and of length of admission.

Adult↗

PubMed2002

Drowning.

Recent epidemiologic data have shown that the burden of drowning is much greater than expected. Prevention and timely rescue are the most effective means of reducing the number of persons at risk. Early bystander cardiopulmonary resuscitation is the most important factor for survival after submersion. Cerebral damage is a serious threat when the hypoxic period is too long. In most situations, low body temperature is an indication of the severity of the drowning incident. Sometimes hypothermia that occurs during the submersion period can be brain protective. There is also new evidence to support the strategy of inducing mild hypothermia for a period of 12 to 24 hours in comatose drowning victims. In immersed patients, hypothermia should be treated. The most appropriate technique will depend on the available means in the hospital and the condition of the patient. Treatment of pulmonary complications depends on the lung injury that occurred during aspiration and the bacteria involved in aspiration. Understanding the pathophysiology of drowning may help us to understand lung injuries and ischemic brain injuries.

Brain Ischemia↗

PubMedDate not supplied

Radiofrequency denervation of lumbar facet joints in the treatment of chronic low back pain: a randomized, double-blind, sham lesion-controlled trial.

OBJECTIVES: Radiofrequency facet joint denervation procedures have been common practice for 2 decades in treatment of chronic low back pain. We designed this multicenter, randomized, double-blind, sham treatment controlled trial to determine the efficacy of radiofrequency facet joint denervation, as it is routinely performed. METHODS: Inclusion criteria were low back pain, duration more than 6 months, and >or=50% Visual Analog Scale (VAS) reduction on diagnostic block. Exclusion criteria were prior radiofrequency treatment, radicular syndrome, coagulopathies, specific allergies, cancer, and pregnancy. A total of 81 out of 462 patients were randomized to undergo radiofrequency facet joint denervation or sham treatment. The first evaluation was carried out 3 months after treatment. Primary outcome was determined with a combined outcome measure comprising VAS, physical activities, and analgesic intake, from a twice-weekly recorded diary. Secondary outcome measures were the separate diary parameters, global perceived effect (complete relief, >50% relief, no effect, pain increase), and SF-36 Quality of Life Questionnaire. RESULTS: There were no dropouts before the first evaluation. The combined outcome measure showed no differences between radio- frequency facet joint denervation (n=40; success 27.5%) and sham (n=41; success 29.3%) (P=0.86). The VAS in both groups improved (P<0.001). Global perceived effect improved after radiofrequency facet joint denervation (P<0.05). The other secondary outcome parameters showed no significant differences. Relevant costs were evaluated. DISCUSSION: The combined outcome measure and VAS showed no difference between radiofrequency and sham, though in both groups, significant VAS improvement occurred. The global perceived effect was in favor of radiofrequency. In selected patients, radiofrequency facet joint denervation appears to be more effective than sham treatment.

Adolescent↗