Comparison of hyperkalemic cardioplegia with altered [CaCl2] and [MgCl2] on [Ca2+]i transients and function after warm global ischemia in isolated hearts.

AIM: [MgCl(2)] and [CaCl(2)] may modify the cardioprotective effects of hyperkalemic cardioplegia (CP). We changed [MgCl(2)] and [CaCl(2)] in a CP solution to examine their effects on [Ca(2+)]i transients and cardiac function before and after global normothermic ischemia. METHODS: After stabilization and loading of indo 1-AM in Kreb's solution (KR), each heart was perfused with either KR or 1 of 4 CP solutions before 37 degrees C, 30 min ischemia followed by reperfusion with KR. The KR solution contained, in mM, 4.5 KCl, 2.4 MgCl(2) and 2.5 CaCl(2); the CP solutions had in addition to 18 KCl: CP 1 (control CP): 2.4 MgCl(2), 2.5 CaCl(2); CP 2: 7.2 MgCl(2), 2.5 CaCl(2); CP 3, 7.2 MgCl(2), 1.25 CaCl(2); CP 4: 2.4 MgCl(2), 1.25 CaCl(2). RESULTS: In the KR group [Ca(2+)]i markedly increased on early reperfusion while functional return (LVP, dLVP/dt((max and min))) was much reduced; each CP group led to reduced [Ca(2+)]i loading and improved function. The rates of cytosolic Ca(2+) fluxes (d[Ca(2+)]/dt(max) and d[Ca(2+)]/dt(min)) increased significantly compared to baseline in the KR group, but were mostly suppressed in the CP groups, and d[Ca(2+)]/dt(min) was lower after CP 4 compared to CP 1 on reperfusion. At 60 min reperfusion, LVP area to [Ca(2+)] area and cardiac efficiency to phasic [Ca(2+)] relationships were shifted after KR, but not after CP 1-4. With similar functional recovery, [Ca(2+)] transient and [Ca(2+)] area were significantly lower after CP 4 than after CP 1. CONCLUSION: Increasing [MgCl(2)] (CP 2 and 3) did not improve cardiac function or reduce Ca(2+) transients on reperfusion better than the other CP groups, but reducing [CaCl(2)] (CP 3 and 4) was more effective in reducing [Ca(2+)] transients on reperfusion after global ischemia.

Sedation assessment in critically ill patients with bispectral index.

BACKGROUND AND OBJECTIVE: Clinical sedation assessment becomes insufficient in deeply sedated patients. Bispectral index as a processed electroencephalogram parameter provides a continuous and observer-independent value reported to change with sedation. The aim of this prospective observational study was to determine the reliability and possible confounding factors of the bispectral index to assess sedation in surgical intensive care patients. METHODS: Following major surgery, bispectral index, body temperature and electromyographic activity of 44 ventilated patients were recorded. Sedation levels were assessed with Ramsay sedation score. RESULTS: Although bispectral index correlated with Ramsay sedation score (-0.64; P < 0.01) we found that in deeply sedated patients temperature instability and electromyographic activity increased bispectral index. Bispectral index correlated significantly with electromyographic activity (0.80; P < 0.01) and with an increase of body temperature (0.55; P < 0.01) not only in all patients but also in clinically deeply sedated patients (0.57; P < 0.01 and 0.46; P < 0.05). CONCLUSIONS: Only under certain conditions, such as low muscular activity and body temperature stability, may the bispectral index be a useful addition to clinical scoring in the sedation assessment of critically ill patients.