A study to evaluate the first dose of gentamicin needed to achieve a peak plasma concentration of 30 mg/l in patients hospitalized for severe sepsis.

Previous studies have shown that the high dose of gentamicin (8 mg/kg) rarely achieves the desired peak plasma concentration (Cmax) of ≥30 mg/l in patients with severe sepsis or septic shock. The aim of this study was to determine the first dose of gentamicin needed to achieve a Cmax ≥ 30 mg/l. We conducted a prospective observational cohort study in one intensive care unit. All consecutive patients hospitalized for severe sepsis or septic shock and treated with a first dose of gentamicin >6 mg/kg were evaluated. During the study period, 15 of the 57 patients (26.3 %) treated with gentamicin had a Cmax ≥ 30 mg/l. The median dose of gentamicin administered was 8.9 [7.8-9.9] mg/kg. Independent factors in the multivariate analysis associated with a Cmax ≥ 30 mg/l were higher body mass index (per kg/m(2) increment) (OR: 1.173, 95%CI: 1.015-1.356, P = 0.03) and higher first dose of gentamicin (per mg/kg increment) (OR: 2.343, 95%CI: 1.346-4.08, P = 0.003). The optimal first dose to achieve a Cmax ≥ 30 mg/l was 11 mg/kg, with a specificity and a sensitivity of 100 % and 53.3 % respectively. These results suggest that a first dose of gentamicin >11 mg/kg is needed to achieve a Cmax ≥ 30 mg/l in most patients.

Genetic selection on a behavioural fear trait is associated with changes in heart rate variability in quail.

This study investigated whether genetic selection on a divergent behavioural trait of fearfulness (tonic immobility duration) was related to changes in the nervous control of the heart. Quail selected for either long or short tonic immobility (LTI or STI, respectively) duration was compared with an unselected control line (CTI). The autonomic control of the heart was assessed by heart rate variability analysis and pharmacological blockades. Quail were surgically fitted with a telemetric device. Heart rate before injection did not differ between the three lines. The vagal-sympathetic effect (VSE) at rest differed significantly from 1 in CTI and STI quail, suggesting that parasympathetic activity was dominant. In LTI quail, VSE did not differ from 1, suggesting a balance between parasympathetic and sympathetic activities. The intrinsic heart rate reached after the successive injections of propranolol and atropine did not differ between lines and was higher than the heart rate at rest in STI, which was in line with results of VSE at rest. After atropine injection, the sympathetic activity indicated by the low-frequency power was lower in CTI than in the two selected quail. After propranolol injection, the parasympathetic activity indicated by the root of the mean squares of successive differences and the high-frequency power was higher in STI than in CTI and LTI quail. Selection on tonic immobility duration thus appears to be associated with changes in the sympathovagal control of the heart, which may influence behavioural responses to stressful situations.

Emotional reactivity modulates autonomic responses to an acoustic challenge in quail.

Emotional reactivity modulates autonomic responses to an acoustic challenge in quail. Physio Behav 00(0) 000-000, 2006. This study investigated the relationship between emotional reactivity and behavioral and autonomic responses to an acoustic stimulus in quail. It was hypothesized that birds with high emotional reactivity would have higher motor inhibition combined with higher sympathetic activation than birds with low emotional reactivity. Two experiments were performed. The first looked for correlations between emotional reactivity, evaluated by a tonic immobility test, and motor and Heart Rate Variability in relation to an acoustic stimulus. The second experiment compared the motor and autonomic responses to the acoustic stimulus of quail selected on either long (LTI) or short (STI) duration of tonic immobility. The first experiment showed that the acoustic stimulation induced motor inhibition and cardiac activation. Correlations were found between tonic immobility duration and both autonomic activity before stimulation and sympathovagal balance after stimulation. In the second experiment, LTI quail showed strong sympathetic activation, whereas STI quail showed parasympathetic and sympathetic activation. The activation of the parasympathetic system induced by the noise in STI quail can be explained by the predominance of this system at rest in this line. In conclusion, both the basal autonomic activity and the autonomic responses differed according to the emotional reactivity, and changes in autonomic activity appear to be related to the genetic selection process.

Serum somatomedin activity following adult tibial shaft fractures.

Serum somatomedin (SM) activity was measured serially in 27 adults with closed tibial shaft fractures. SM activity was found to be normal in all but one specimen. The results indicate that SM activity does not reflect severity of trauma or the ability to heal on time in these fractures.