Mild hypothermia induces incomplete left ventricular relaxation despite spontaneous bradycardia in pigs.

AIM: Mild hypothermia (MH) decreases left ventricular (LV) end-diastolic capacitance. We sought to clarify whether this results from incomplete relaxation. METHODS: Ten anaesthetized pigs were cooled from normothermia (NT, 38 °C) to MH (33 °C). LV end-diastolic pressure (LVPed), volume (LVVed) and pressure-volume relationships (EDPVRs) were determined during stepwise right atrial pacing. LV capacitance (i.e. LVVed at LVPed of 10 mmHg, LV VPed10) was derived from the EDPVR. Pacing-induced changes of diastolic indices (LVPed, LVVed and LV VPed10) were analysed as a function of (i) heart rate and (ii) the ratio between diastolic time interval (t-dia) and LV isovolumic relaxation constant τ, which was calculated using a logistic fit (τL ) and monoexponential fit with zero asymptote (τZ ) and nonzero asymptote (τNZ ). RESULTS: Mild hypothermia decreased heart rate (85 ± 4 to 68 ± 3 bpm), increased τL (22 ± 1 to 57 ± 4 ms), τZ (26 ± 2 to 56 ± 5 ms) and τNZ (41 ± 1 to 96 ± 5 ms), decreased t-dia/τ ratios, and shifted the EDPVR leftwards compared to NT (all P < 0.05). During NT, pacing at ≥140 bpm shifted the EDPVR progressively leftwards. During MH, relationships between diastolic indices and heart rate were shifted towards lower heart rates compared to NT. However, relationships between diastolic indices and t-dia/τ during NT and MH were superimposable. CONCLUSION: We conclude that the loss of LV end-diastolic capacitance during MH can be explained at least in part by slowed LV relaxation. MH thereby is an example of incomplete LV relaxation at a spontaneous low heart rate. Caution may be advised, when heart rate is increased in patients treated with MH.

Semi-permanent skin staining associated with silver-coated wound dressing Acticoat.

A 17-year-old male with burns to 8% of his total body surface area was treated for 10 days with Acticoat(®), a nanocrystalline silver dressing. The burns, which were on his back and shoulder, healed without infection. However, a skin discoloration in the wound area and the adjacent uninjured skin appeared in the first days of treatment. The staining remained visible even after the treatment had ended and disappeared approximately three years later. Despite the outstanding antimicrobial properties, possible side effects of silver nanocrystalline dressings should be kept in mind.

Un garçon de 17 ans avec des brûlures sur 8% de la surface corporelle totale a été traité avec Acticoat®, un pansement d'argent nanocristallin, pendant 10 jours. Les brûlures, qui étaient sur son dos et une épaule, ont guéri sans infections. Cependant, une décoloration de la peau dans la zone de la plaie et la peau indemne adjacente est apparue dans les premiers jours de traitement. La coloration est restée visible même après le fin du traitement et elle a disparu environ trois ans plus tard. Malgré ses propriétés antimicrobiennes importantes, il faut considérer les effets secondaires possibles de pansements d'argent nanocristallins.