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Articles by M Winterhalter
Total Records ( 2 ) for M Winterhalter
  S Munte , J Klockars , M van Gils , A Hiller , M Winterhalter , C Quandt , M Gross and T. Taivainen
 

BACKROUND: The Narcotrend® electr oencephalogram monitor is designed to measure hypnotic state during anesthesia. We performed this study to evaluate the effectiveness and reliability of the Narcotrend monitor in assessing hypnotic state and loss of consciousness (LOC) during propofol anesthesia induction in children.

METHODS: Sixty-two children, aged 1–5 (n = 17), 6–12 (n = 23), and 13–16 (n = 21) yr, scheduled for elective surgery were studied. The patients were premedicated with oral midazolam 0.5 mg/kg. After IV access, propofol target controlled infusion (TCI) was started with 0.5 µg/mL and increased by 0.5 µg/mL increments every 2 min until the child did not respond to any verbal command or physical stimuli. A manual scheme was used for children weighing <15 kg. Hypnotic state was measured every minute from the start of the propofol infusion using the University of Michigan Sedation Scale (UMSS). LOC was defined as a transition of UMSS scale value 2 to 3. The Narcotrend index (NI) was recorded before the start of induction and during the whole study period. NI values were noted simultaneously, yet independently of the sedation measurements. Prediction probability (PK) was used to assess the correspondence between NI and UMSS. Sensitivity and specificity of NI for differentiating between consciousness and unconsciousness were calculated. NI values at specific UMSS levels were compared between the different age groups and the relationships between TCI propofol concentrations and sedation levels were assessed using correlation analysis.

RESULTS: A PK-value of 0.84 (95% CI [0.80–0.88]) of NI was calculated from the data for the detection of LOC. Similarly, a PK value of 0.82 (95% CI [0.78–0.86]) indicated agreement between NI and UMSS values. The average NI values differed between successive UMSS sedation levels 0 and 1 and levels 1 and 2 (P < 0.01). In the youngest age group, the NI discriminated between UMSS levels 2 and 3, in the second age group between levels 1 and 2 and 2 and 3, and in the oldest age group between 0 and 1. Furthermore, the NI values differed significantly between age groups at UMSS levels 1–4 (P < 0.005), with the NI values being higher in younger compared with older children. The average NI value at LOC was 68. For the detection of consciousness, a sensitivity of 0.67 and specificity of 0.79 were achieved. Spearman correlation coefficients indicated higher association between TCI propofol concentrations and UMSS (0.96) than between NI and UMSS (–0.68).

CONCLUSIONS: During propofol induction in children, the Narcotrend electroencephalogram monitor was capable of following changes in the sedation level of children to some extent, but also had a relatively high probability (0.18) of incorrectly predicting changes in conscious state. Therefore, the monitor should not solely be used to guide sedation and anesthesia. NI was age-dependent and younger children had higher NI-values than older children at the same level of sedation.

  N Rahe Meyer , M Pichlmaier , A Haverich , C Solomon , M Winterhalter , S Piepenbrock and K. A. Tanaka
  Background

Bleeding diathesis after aortic valve operation and ascending aorta replacement (AV–AA) is managed with fresh-frozen plasma (FFP) and platelet concentrates. The aim was to compare haemostatic effects of conventional transfusion management and FIBTEM (thromboelastometry test)-guided fibrinogen concentrate administration.

Methods

A blood products transfusion algorithm was developed using retrospective data from 42 elective patients (Group A). Two units of platelet concentrate were transfused after cardiopulmonary bypass, followed by 4 u of FFP if bleeding persisted, if platelet count was ≤100x103 µl–1 when removing the aortic clamp, and vice versa if platelet count was >100x103 µl–1. The trigger for each therapy step was ≥60 g blood absorbed from the mediastinal wound area by dry swabs in 5 min. Assignment to two prospective groups was neither randomized nor blinded; Group B (n=5) was treated according to the algorithm, Group C (n=10) received fibrinogen concentrate (Haemocomplettan® P/Riastap, CSL Behring, Marburg, Germany) before the algorithm-based therapy.

Results

A mean of 5.7 (0.7) g fibrinogen concentrate decreased blood loss to below the transfusion trigger level in all Group C patients. Group C had reduced transfusion [mean 0.7 (range 0–4) u vs 8.5 (5.3) in Group A and 8.2 (2.3) in Group B] and reduced postoperative bleeding [366 (199) ml vs 793 (560) in Group A and 716 (219) in Group B].

Conclusions

In this pilot study, FIBTEM-guided fibrinogen concentrate administration was associated with reduced transfusion requirements and 24 h postoperative bleeding in patients undergoing AV–AA.

 
 
 
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