Brain perfusion evaluated by regional tissue oxygenation as a possible quality indicator of ongoing cardiopulmonary resuscitation. An experimental porcine cardiac arrest study.

INTRODUCTION: Relationship between regional tissue oxygenation (rSO2) and microcirculatory changes during cardiac arrest (CA) are still unclear. Therefore, we designed an experimental study to correlate rSO2, microcirculation and systemic hemodynamic parameters in a porcine model of CA. METHODS: Ventricular fibrillation was induced in 24 female pigs (50±3kg) and left for three minutes untreated followed by five minutes of mechanical CPR. Regional and peripheral saturations were assessed by near-infrared spectroscopy, sublingual microcirculation by Sidestream Dark Field technology and continuous hemodynamic parameters, including systemic blood pressure (MAP) and carotid blood flow (CF), during baseline, CA and CPR periods. The Wilcoxon Signed-Rank test, the Friedman test and the partial correlation method were used to compare these parameters. RESULTS: Brain and peripheral rSO2 showed a gradual decrease during CA and only an increase of brain rSO2 during mechanical CPR (34.5 to 42.5; p=0.0001), reflected by a rapid decrease of microcirculatory and hemodynamic parameters during CA and a slight increase during CPR. Peripheral rSO2 was not changed significantly during CPR (38 to 38.5; p=0.09). We only found a moderate correlation of cerebral/peripheral rSO2 to microcirculatory parameters (PVD: r=0.53/0.46; PPV: r=0.6/0.5 and MFI: r=0.64/0.52) and hemodynamic parameters (MAP: r=0.64/0.71 and CF: 0.71/0.67). CONCLUSIONS: Our experimental study confirmed that monitoring brain and peripheral rSO2 is an easy-to-use method, well reflecting the hemodynamics during CA. However, only brain rSO2 reflects the CPR efforts and might be used as a potential quality indicator for CPR.

Microvascular perfusion in cardiac arrest: a review of microcirculatory imaging studies.

Cardiac arrest represents a leading cause of mortality and morbidity in developed countries. Extracorporeal cardiopulmonary resuscitation (ECPR) increases the chances for a beneficial outcome in victims of refractory cardiac arrest. However, ECPR and post-cardiac arrest care are affected by high mortality rates due to multi-organ failure syndrome, which is closely related to microcirculatory disorders. Therefore, microcirculation represents a key target for therapeutic interventions in post-cardiac arrest patients. However, the evaluation of tissue microcirculatory perfusion is still demanding to perform. Novel videomicroscopic technologies (Orthogonal polarization spectral, Sidestream dark field and Incident dark field imaging) might offer a promising way to perform bedside microcirculatory assessment and therapy monitoring. This review aims to summarise the recent body of knowledge on videomicroscopic imaging in a cardiac arrest setting and to discuss the impact of extracorporeal reperfusion and other therapeutic modalities on microcirculation.

Effect of Pulsatility on Microcirculation in Patients Treated with Extracorporeal Cardiopulmonary Resuscitation: A Pilot Study.

The effect of pulsatile blood flow on microcirculation during extracorporeal cardiopulmonary resuscitation (ECPR) is not elucidated; therefore, we designed an observational study comparing sublingual microcirculation in patients with refractory cardiac arrest (CA) with spontaneously pulsatile or low/nonpulsatile blood flow after treatment with ECPR. Microcirculation was assessed with Sidestream Dark Field technology in 12 patients with CA who were treated with ECPR and 12 healthy control subjects. Microcirculatory images were analyzed offline in a blinded fashion, and consensual parameters were determined for the vessels ≤20 µm. The patients' data, including actual hemodynamic parameters, were documented. Pulsatile blood flow was defined by a pulse pressure (PP) ≥ 15 mm Hg. Compared with the healthy volunteers, the patients who were treated with ECPR exhibited a significantly lower proportion of perfused capillaries (PPC); other microcirculatory parameters did not differ. The groups of patients with pulsatile (n = 7) versus low/nonpulsatile (n = 5) blood flow did not differ in regards to the collected data and hemodynamic variables (except for the PP and ejection fraction of the left ventricle) as well as microcirculatory parameters. In conclusion, microcirculation appeared to be effectively supported by ECPR in our group of patients with CA with the exception of the PPC. We found only nonsignificant contribution of spontaneous pulsatility to extracorporeal membrane oxygenation-generated microcirculatory blood flow.

Microcirculatory blood flow during cardiac arrest and cardiopulmonary resuscitation does not correlate with global hemodynamics: an experimental study.

BACKGROUND: Current research highlights the role of microcirculatory disorders in post-cardiac arrest patients. Affected microcirculation shows not only dissociation from systemic hemodynamics but also strong connection to outcome of these patients. However, only few studies evaluated microcirculation directly during cardiac arrest (CA) and cardiopulmonary resuscitation (CPR). The aim of our experimental study in a porcine model was to describe sublingual microcirculatory changes during CA and CPR using recent videomicroscopic technology and provide a comparison to parameters of global hemodynamics. METHODS: Cardiac arrest was induced in 18 female pigs (50 ± 3 kg). After 3 min without treatment, 5 min of mechanical CPR followed. Continuous hemodynamic monitoring including systemic blood pressure and carotid blood flow was performed and blood lactate was measured at the end of baseline and CPR. Sublingual microcirculation was assessed by the Sidestream Dark Field (SDF) technology during baseline, CA and CPR. Following microcirculatory parameters were assessed off-line separately for capillaries (≤20 µm) and other vessels: total and perfused vessel density (TVD, PVD), proportion of perfused vessels (PPV), microvascular flow index (MFI) and heterogeneity index (HI). RESULTS: In comparison to baseline the CA small vessel microcirculation was only partially preserved: TVD 15.64 (13.59-18.48) significantly decreased to 12.51 (10.57-13.98) mm/mm(2), PVD 15.57 (13.56-17.80) to 5.53 (4.17-6.60) mm/mm(2), PPV 99.64 (98.05-100.00) to 38.97 (27.60-46.29) %, MFI 3.00 (3.00-3.08) to 1.29 (1.08-1.58) and HI increased from 0.08 (0.00-0.23) to 1.5 (0.71-2.00), p = 0.0003 for TVD and <0.0001 for others, respectively. Microcirculation during ongoing CPR in small vessels reached 59-85 % of the baseline values: TVD 13.33 (12.11-15.11) mm/mm(2), PVD 9.34 (7.34-11.52) mm/mm(2), PPV 72.34 (54.31-87.87) %, MFI 2.04 (1.58-2.42), HI 0.65 (0.41-1.07). The correlation between microcirculation and global hemodynamic parameters as well as to lactate was only weak to moderate (i.e. Spearman's ρ 0.02-0.51) and after adjustment for multiple correlations it was non-significant. CONCLUSIONS: Sublingual microcirculatory parameters did not correlate with global hemodynamic parameters during simulated porcine model of CA and CPR. SDF imaging provides additional information about tissue perfusion in the course of CPR.

Local electrogram delay recorded from left ventricular lead at implant predicts response to cardiac resynchronization therapy: retrospective study with 1 year follow up.

BACKGROUND: Considerable proportion of patients does not respond to the cardiac resynchronization therapy (CRT). This study investigated clinical relevance of left ventricular electrode local electrogram delay from the beginning of QRS (QLV). We hypothesized that longer QLV indicating more optimal lead placement in the late activated regions is associated with the higher probability of positive CRT response. METHODS: We conducted a retrospective, single-centre analysis of 161 consecutive patients with heart failure and LBBB or nonspecific intraventricular conduction delay (IVCD) treated with CRT. We routinely intend to implant the LV lead in a region with long QLV. Clinical response to CRT, left ventricular (LV) reverse remodelling (i.e. decrease in LV end-systolic diameter - LVESD ≥10%) and reduction in plasma level of NT-proBNP >30% at 12-month post-implant were the study endpoints. We analyzed association between pre-implant variables and the study endpoints. RESULTS: Clinical CRT response rate reached 58%, 84% and 92% in the lowest (≤105 ms), middle (106-130 ms) and the highest (>130 ms) QLV tertile (p < 0.0001), respectively. Longer QRS duration (p = 0.002), smaller LVESD and a non-ischemic cardiomyopathy (both p = 0.02) were also univariately associated with positive clinical CRT response. In a multivariate analysis, QLV remained the strongest predictor of clinical CRT response (p < 0.00001), followed by LVESD (p = 0.01) and etiology of LV dysfunction (p = 0.04). Comparable predictive power of QLV for LV reverse remodelling and NT-proBNP response rates was observed. CONCLUSION: LV lead position assessed by duration of the QLV interval was found the strongest independent predictor of beneficial clinical response to CRT.