Biomedical subjects

P Kranke

Publications and source records attributed to P Kranke.

33 records · Page 2Linked to original sources

PubMed2003

[Evidence-based medicine and anaesthesiology--six steps towards implementation into clinical practice].

Whenever evidence-based medicine (EbM) is mentioned among physicians, it evokes many different and contradictory reactions. On the one hand a lot of physicians have heard of this concept, but may hardly associate anything with it. On the other hand most of the physicians seem to be skeptical rather than in favour of evidence-based medicine. They seem to be concerned about restrictions in daily clinical decision-making or negative implications for the relationship between patient and physician. In this article we would like to deal with the question whether evidence-based medicine is useful for clinicians and which chances are provided for both the physicians and the patients by using it. First, the methodology and aims of evidence-based medicine are introduced. Second, by using an example of clinical anaesthesiology, we discuss the six formal steps for implementing this method. Third, important points which help to assess clinical studies are mentioned. In conclusion we would like to point out that evidence-based medicine is no entirely new concept of medicine but aims to highlight a solid and conscientious scientific basis of clinical decision-making. Thus, evidence-based medicine may act as a methodological strategy helping to clear the proceedings of decision-making and improve the provision of medical care to patients. Furthermore, it may guarantee a rapid transfer of knowledge from outcome-related research to patient care.

Anesthesiology↗

PubMed2002

[Transient neurologic symptoms after spinal anesthesia. A quantitative systematic overview (meta-analysis) of randomized controlled studies].

BACKGROUND: Transient neurologic symptoms (TNS) after spinal anesthesia (SPA) is defined as back pain with radiation or dysesthesia in the buttocks, thighs, hips and calves, occurring within 24 h after recovery from otherwise uneventful SPA. The symptoms last for about 1-3 days but neurophysiologic evaluation does not show pathologic findings. The type and the preparation of the local anesthetic drug (baricity, concentration, additives or preservatives) are most often discussed as the underlying cause of TNS. METHODS: Randomized controlled comparative studies reporting the incidence of TNS were systematically searched. Descriptive statistics are presented summarizing the identified trials and the pooled relative risk (RR), the number-needed-to-harm (NNH) with their 95% confidence intervals (95%-CI) were calculated using a random effects model. RESULTS: A total of 29 studies with a 2,813 patients fulfilled the inclusion criteria. Summarizing all patients in these trials without further adjustment, the incidence of TNS was 16.9% after lidocaine, 19.1% after mepivacaine, but only 1.1% after bupivacaine and 1.7% after prilocaine. For tetracaine, procaine, and ropivacaine there were too few studies to draw meaningful conclusions. Using meta-analysis techniques these data were confirmed: the pooled relative risk (RR) for suffering from TNS was 6.7-fold higher after lidocaine (95%-CI: 2.5-18) than after SPA with bupivacaine and 5.5-fold higher (95%-CI: 2-15) than after prilocaine. Furthermore, data show that baricity, concentration of the local anesthetic, and addition of vasoconstrictors have no significant influence on the occurrence of TNS. CONCLUSION: Prilocaine and bupivacaine for SPA are associated with less TNS than lidocaine and mepivacaine. For the other local anesthetics there were not enough comparative trials to give conclusive recommendations.

Adjuvants, Anesthesia↗

PubMed2002

[Tropisetron for prevention of postoperative nausea and vomiting: a quantitative systematic review].

OBJECTIVE: A quantitative systematic review of randomised controlled trials investigating the efficacy of tropisetron versus placebo to prevent postoperative nausea (PN) and vomiting (PV) as well as PN and/or PV (PONV). METHODS: The relevant results for the 24 h postoperative period were extracted from systematically searched studies (MEDLINE, EMBASE, Cochrane-Library, reference lists; last update December 2001). RESULTS: In 19 studies and 22 comparisons, 1,012 patients received a placebo and 1,267 patients tropisetron and the pooled analyses (2-5 mg iv) are presented. The relative risks (RR) for PN, PV and PONV with tropisetron prophylaxis were 0.72 (95%-CI: 0.62-0.83), 0.59 (95%-CI: 0.47-0.73) and 0.70 (95%-CI: 0.62-0.79), respectively. The RR for rescue treatment was 0.63 (95%-CI: 0.54-0.74). The RR in children for a variable dose of 0.1-0.2 mgxkg(-1) was 0.49 (95%-CI: 0.38-0.63), 0.49 (95%-CI: 0.38-0.63) and 0.32 (95%-CI: 0.15-0.70) for PV, PONV and rescue treatment, respectively. Restricting the analysis to a predefined control event rate of 40-80% revealed that about 6-7 patients need to be treated with tropisetron for PN to be prevented in 1 patient who would have had PN if all had received a placebo (NNT=6.7; 95%-CI: 4.8-11.1). The corresponding NNT for preventing PV and PONV was 5.0 (95%-CI: 3.6-8.3) and 4.6 (95%-CI: 3.6-6.3), respectively. CONCLUSION: Tropisetron significantly reduced the incidence of PONV. There is no clear evidence for a dose response between 2 and 5 mg iv. For children a dose of 0.1 mgxkg(-1) of body weight is effective. Sufficient data for the oral application of tropisetron are lacking.

Administration, Oral↗

PubMed2002

Dimenhydrinate for prophylaxis of postoperative nausea and vomiting: a meta-analysis of randomized controlled trials.

BACKGROUND: Diphenhydramine and its theoclate salt dimenhydrinate are traditional antiemetics still in use. However, so far the quantitative effect of dimenhydrinate in the prophylaxis of postoperative nausea and vomiting (PONV) has not been evaluated systematically. METHODS: Results from randomized controlled trials investigating the efficacy of dimenhydrinate vs. a control to prevent PONV were included in a meta-analysis. Studies were systematically searched through MEDLINE, EMBASE, the Cochrane-Library, manually screening of reference lists of matching review articles and current issues of locally available peer-reviewed anesthesia journals, up to June 2001. The numbers of patients with complete absence of PONV within 6 h and within 48 h after surgery were extracted as the main end point. Pooled relative benefits (RB) and numbers-needed-to-treat (NNT) with their corresponding 95% confidence intervals (CI) were calculated using a random effects model. This quantitative systematic review was performed following the recommendations of the QUORUM statement. In all, 18 trials with 3045 patients were included in the analysis: 1658 patients received a placebo (control) and 1387 patients received dimenhydrinate. RESULTS: The RB to stay completely free of PONV was 1.2 (95% CI: 1.1-1.4) for the early period (NNT = 8; 95% CI: 5-25) and 1.5 (1.3-1.8) for the overall investigated period (NNT = 5; 95% CI: 3-9). CONCLUSION: Dimenhydrinate is a traditional and inexpensive antiemetic with an efficacy that might be considered as clinically relevant. Although in use for a long time, the dose-response, precise estimation of side-effects, optimal time of administration and the benefit of repetitive doses still remain unclear.

Adult↗

PubMed2002

Comparison of predictive models for postoperative nausea and vomiting.

BACKGROUND: In order to identify patients who would benefit from prophylactic amtiemetics, six predictive models have been described for the risk assessment of postoperative nausea and vomiting (PONV). This study compared the validity and practicability of these models in patients undergoing general anaesthesia. METHODS: Data were analysed from 1566 patients who underwent balanced anaesthesia without prophylactic antiemetic treatment for various types of surgery. A systematic literature search identified six predictive models for PONV. These models were compared with respect to validity (discriminating power and calibration characteristics) and practicability. Discriminating power was measured by the area under the receiver operating characteristic curve (AUC) and calibration was assessed by weighted linear regression analysis between predicted and actual incidences of PONV. Practicability was assessed according to the number of factors to be considered for the model (the fewer factors the better), and whether the score could be used in combination with a previously applied cost-effective concept. RESULTS: The incidence of PONV was 600/1566 (38.1%). The discriminating power (AUC) obtained by the models (named according to the first author) using the risk classes from the recommended prophylactic concept were as follows: Apfel, 0.68; Koivuranta, 0.66; Sinclair, 0.66; Palazzo, 0.63; Gan, 0.61; Scholz, 0.61. For four models, the following calibration curves (expressed as the slope and the offset) were plotted: Apfel, y=0.82x+0.01, r2=0.995; Koivuranta, y=1.13x-0.10, r2=0.999; Sinclair, y=0.49x+0.29, r2=0.789; Palazzo, y=0.30x+0.30, r2=0.763. The numbers of parameters to be considered were as follows: Apfel, 4; Koivuranta, 5; Palazzo, 5; Scholz, 9; Sinclair, 12; Gan, 14. CONCLUSION: The simplified risk scores provided better discrimination and calibration properties compared with the more complex risk scores. Therefore, simplified risk scores can be recommended for antiemetic strategies in clinical practice as well as for group comparisons in randomized controlled antiemetic trials.

Adult↗

PubMed2002

Volatile anaesthetics may be the main cause of early but not delayed postoperative vomiting: a randomized controlled trial of factorial design.

BACKGROUND: Despite intensive research, the main causes of postoperative nausea and vomiting (PONV) remain unclear. We sought to quantify the relative importance of operative, anaesthetic and patient-specific risk factors to the development of PONV. METHODS: We conducted a randomized controlled trial of 1180 children and adults at high risk for PONV scheduled for elective surgery. Using a five-way factorial design, we randomly assigned subjects by gender who were undergoing specific operative procedures, to receive various combinations of anaesthetics, opioids, and prophylactic antiemetics. RESULTS: Of the 1180 patients, 355 (30.1% 95% CI (27.5-32.7%)) had at least one episode of postoperative vomiting (PV) within 24 h post-anaesthesia. In the early postoperative period (0-2 h), the leading risk factor for vomiting was the use of volatile anaesthetics, with similar odds ratios (OR (95% CI)) being found for isoflurane (19.8 (7.7-51.2)), enflurane (16.1 (6.2-41.8)) and sevoflurane (14.5 (5.6-37.4)). A dose-response relationship was present for the use of volatile anaesthetics. In contrast, no dose response existed for propofol anaesthesia. In the delayed postoperative period (2-24 h), the main predictors were being a child (5.7 (3.0-10.9)), PONV in the early period (3.4 (2.4-4.7)) and the use of postoperative opioids (2.5 (1.7-3.7)). The influence of the antiemetics was considerably smaller and did not interact with anaesthetic or surgical variables. CONCLUSION: Volatile anaesthetics were the leading cause of early postoperative vomiting. The pro-emetic effect was larger than other risk factors. In patients at high risk for PONV, it would therefore make better sense to avoid inhalational anaesthesia rather than simply to add an antiemetic, which may still be needed to prevent or treat delayed vomiting.

Adolescent↗

PubMed2001

The influence of a dominating centre on a quantitative systematic review of granisetron for preventing postoperative nausea and vomiting.

BACKGROUND: We performed a meta-analysis on granisetron in the prevention of postoperative nausea and vomiting (PONV) and further investigated whether total results and the dose-response characteristics may be significantly affected by a single centre. METHODS: Systematically searched randomised controlled trials (RCT) using granisetron for the prevention of PONV after general anaesthesia were included in the analysis. The pooled relative risks (RR) and numbers needed to treat (NNT) with their corresponding 95%-confidence intervals (CI) were calculated. For all centres, one dominating centre and other centres pooled, comparisons were performed according to all doses, low dose ( 20 microg/kg) granisetron. RESULTS: A total of 27 RCT with 2938 patients were included in the analysis. RR (CI) to suffer from PONV with granisetron when all comparisons were considered was 0.46 (0.39-0.54), 0.7 (0.6-0.81) and 0.34 (0.28-0.41) for all doses, low and high dose, respectively. RR of the dominating centre (1867 patients) were significantly better compared to the remaining centres (1071 patients), with 0.41 (0.34-0.49) and 0.60 (0.49-0.73), respectively. In the dominating centre low dose granisetron was ineffective with a RR of 0.84 (0.68-1.04), while high dose granisetron led to a strong decrease with a RR of 0.30 (0.26-0.36). In contrast, the RR of other centres pooled for low and high dose granisetron were comparable with 0.62 (0.49-0.79) and 0.56 (0.42-0.75), respectively. CONCLUSIONS: Overall results and dose-response characteristics of meta-analyses may be significantly altered by one dominating centre. Further, if data of a dominating centre do not appear to be valid for other centres, it may seem advisable to either exclude them from the analysis or to perform sub-group analyses so that results without the data from the dominating centre are available.

Antiemetics↗

PubMed2001

What can be expected from risk scores for predicting postoperative nausea and vomiting?

Several risk scores have been developed to calculate the probability of postoperative nausea and vomiting (PONV). However, the power to discriminate which individual will suffer from PONV is still limited. Thus, we wondered how the number of predictors in a score affects the discriminating power and how the characteristics of a population--which is needed to measure the power of a score--may affect the results. For ethical reasons and to be independent from centre specific populations, we developed a computer model to simulate virtual populations. Four populations were created according to number, frequency, and odds ratio of predictors. Population I: parameters were derived from a previously published paper to verify whether calculated and reported values are in accordance. Population II: a gynaecological population was created to investigate the impact of the study setting. Populations III and IV: to meet ideal assumptions a model with up to seven predictors with an odds ratio of 2 and 3 was tested, respectively. The discriminating power of a risk score was measured by the area under a receiver operating characteristic curve (AUC) and an increase of more than 0.025 per predictor was considered to be clinically relevant. The AUC of population I was similar to those reported in clinical investigations (0.72). The study setting had a considerable impact on the discriminating power since the AUC decreased to 0.65 in a gynaecological setting. The AUC with the 'idealized' populations III and IV was at best in the range of 0.7-0.8. The inclusion of more than five predictors did not lead to a clinically relevant improvement. The currently available simplified risk scores (with four or five predictors) are useful both as a method to estimate individual risk of PONV and as a method for comparing groups of patients for antiemetic trials. They are also superior to single predictor models which are just using the patients' history of PONV or female gender alone. However, our analysis suggests that the power to discriminate which indvidual will suffer from PONV will remain imperfect, even when more predictors are considered.

Area Under Curve↗

PubMed2001

An increased body mass index is no risk factor for postoperative nausea and vomiting. A systematic review and results of original data.

BACKGROUND: An increased Body Mass Index (BMI) is almost always mentioned as a fundamental risk factor for postoperative nausea (PN), vomiting (PV) or both (PONV). However, multivariate analyses were unable to detect any correlation. Therefore, we asked whether an increased BMI is really a risk factor for PONV. METHODS: For the systematic review, a search of electronic databases and a detailed manual search of reviews were carried out. For the analysis of the original data, 587 adult patients from a randomised controlled antiemetic trial (RCT) who underwent general anaesthesia were allocated to four weight groups: Underweight (BMI < 20), Normal Weight (BMI 20-25), Overweight (BMI 25-30) and Obesity (BMI > or = 30). RESULTS: Four publications with original data were found. Two described a positive relationship, although not clearly supported by the data. Despite this, most narrative reviews claimed a positive correlation between obesity and PONV by quoting again narrative reviews or misquoting originals. In the RCT, the calculated underlying risk profile for PONV was comparable between all groups. Incidences (95% confidence intervals) of PONV were 45.8% (34.0; 57.6), 41.7 (36.5; 46.9), 47.8 (38.4; 57.1) and 44.1 (31.0; 57.1), for the groups Underweight, Normal Weight, Overweight and Obesity, respectively (P=0.69). The incidences of PN and PV also did not differ with P=0.76 and P=0.36, respectively. CONCLUSION: Systematic search of the literature provides no evidence for a positive relationship. Furthermore, our data confirm that an increased BMI is not a risk factor for PONV. This negative finding is important as focussing on the relevant risk factors is needed to allow for an objective risk assessment of PONV.

Body Mass Index↗

PubMed2000