Therapeutic hypothermia and vasopressor dependency after cardiac arrest

Objective

Clinical trials of therapeutic hypothermia (TH) after cardiac arrest excluded patients with persistent hemodynamic instability after return of spontaneous circulation (ROSC), and thus equipoise may exist regarding use of TH in these patients. Our objective was to determine if TH is associated with worsening hemodynamic instability among patients who are vasopressor-dependent after ROSC.

Methods

We performed a prospective observational study in vasopressor-dependent post-cardiac arrest patients. Inclusion criteria were age >17, non-trauma cardiac arrest, comatose after ROSC, and persistent vasopressor dependence. The decision to initiate TH (33–34 °C) was made by the treating physician. We measured cumulative vasopressor index (CVI) and mean arterial pressure (MAP) every 15 min during the first 6 h after ROSC. The outcome measures were change in CVI (primary outcome) and MAP (secondary outcome) over time. We graphed median CVI and MAP over time for the treated and not treated cohorts, and used propensity adjusted repeated measures mixed models to test for an association between TH induction and change in CVI or MAP over time.

Results

Seventy-five post-cardiac arrest patients were included (35 treated; 40 not treated). We observed no major differences in CVI or MAP over time between the treated and not treated cohorts. In the mixed models we found no statistically significant association between TH induction and changes in CVI or MAP.

Conclusion

In patients with vasopressor-dependency after cardiac arrest, the induction of hypothermia was not associated with a decrease in mean arterial pressure or increase in vasopressor requirement.     

Serum glial fibrillary acidic protein as a predictive biomarker of neurological outcome after cardiac arrest

Aim of the study

Serum glial fibrillary acidic protein (GFAP) has recently been identified as a specific predictor of brain damage and neurological outcome in patients with head trauma. In this study, serum GFAP was assessed as a predictor of neurological outcome in post-cardiac-arrest (PCA) patients.

Methods

This study was a retrospective, single-medical-center analysis, conducted in the intensive care unit of a university hospital. Forty-four sequential PCA patients with cardiogenic or non-cardiogenic arrest were included. The patients were treated with or without therapeutic hypothermia (TH). Serum samples were collected from the patients at 12, 24, and 48 h after the return of spontaneous circulation (ROSC). Serum GFAP concentrations were measured by enzyme-linked immunosorbent assay and compared in patients with good and poor neurological outcomes, evaluated over a period of 6 months using Glasgow Outcome Scale.

Results

Serum GFAP was significantly higher in patients with a poor outcome at 12 and 24 h without TH and at 48 h with TH (P < 0.05). GFAP (>0.1 ng dL⁻¹) was a specific predictor of poor neurological outcome at 6 months with or without TH treatment.

Conclusions

Although this study is preliminary, serum GFAP after ROSC reflected a poor neurological outcome in PCA patients.     

Accuracy of continuous thermodilution cardiac output monitoring by pulmonary artery catheter during therapeutic hypothermia in post-cardiac arrest patients

Purpose

Thermodilution continuous cardiac output measurements (TDCCO) by pulmonary artery catheter (PAC) have not been validated during therapeutic hypothermia in post-cardiac arrest patients. The calculated cardiac output based on the indirect Fick principle (FCO) using pulmonary artery blood gas mixed venous oxygen saturation (FCO-BG-SvO2) is considered as the gold standard. Continuous SvO2 by PAC (PAC-SvO2) has also not been validated previously during hypothermia. The aims of this study were (1) to compare FCO-BG-SvO2 with TDCCO, (2) to compare PAC-SvO2 with BG-SvO2 and finally (3) to compare FCO with SvO2 obtained via PAC or blood gas.

Methods

We analyzed 102 paired TDCCO/FCO-BG-SvO2 and 88 paired BG-SvO2/PAC-SvO2 measurements in 32 post-cardiac arrest patients during therapeutic hypothermia.

Results

TDCCO was significantly although poorly correlated with FCO-BG-SvO2 (R² 0.21, p < 0.01) without systematic bias (−0.15 ± 1.76 l/min). Analysis according to Bland and Altman however showed broad limits of agreement ([−3.61; 3.45] l/min) and an unacceptable high percentage error (105%). None of the criteria for clinical interchangeability were met. Concordance analysis showed that TDCCO had limited trending ability (R² 0.03). FCO based on PAC-SvO2 was highly correlated with FCO-BG-SvO2 (R² 0.72) with a small bias (−0.08 ± 0.72 l/min) and slightly too high percentage error (44%).

Conclusion

Our results show an extreme inaccuracy of TDCCO by PAC in post-cardiac arrest patients during therapeutic hypothermia. We found a reasonable correlation between BG-SvO2 and PAC-SvO2 and subsequently between FCO calculated with SvO2 obtained either via blood gas or PAC. The decision to start or titrate inotropics should therefore not be guided by TDCCO in this setting.     

Heparin dosing in critically ill patients undergoing therapeutic hypothermia following cardiac arrest

Purpose

To determine the effects of anticoagulation with intravenous unfractionated heparin (IVUH) during therapeutic hypothermia (TH) post-cardiac arrest.

Methods

Single-center, retrospective, observational trial in the intensive care units of two hospitals within the Detroit Medical Center. Unresponsive survivors of cardiac arrest, receiving treatment doses of IVUH during TH were included. Patients were required to have at least 1 measured activated partial thromboplastin time (aPTT) during TH. Coagulation parameters were collected at 3 distinct temperature phases: baseline, TH, and post-re-warming (±37 °C) target aPTT defined as 1.5–2 times baseline.

Results

Forty-six patients received IVUH during TH, with 211 aPTTs. Heparin starting rate was 13 ± 4 units/kg/h. Average baseline, TH and post-TH aPTT were 34 ± 12, 142 ± 48, and 56 ± 17 s, respectively. Using standard dosing strategies, initial aPTT was above the target range in 89% of patients. After re-warming, aPTT significantly decreased (142 ± 48 s vs 56 ± 17 s, p = 0.005), and heparin dose significantly increased (7.9 ± 3 vs 9 ± 4 units/kg/h, p < 0.001). There was a significant difference between aPTT among all three groups, and heparin dose between TH and post-TH even after correcting for age, sex, body mass index, heparin rate, and APACHE II score (p < 0.001). Three patients experienced a major bleeding event.

Conclusions

Current dosing protocols for IVUH should not be utilized during TH. Heparin requirements are drastically reduced during TH and prolonged interruptions may be required to allow for adequate clearance of UH.     

Prevalence and effect of fever on outcome following resuscitation from cardiac arrest

Objective

Evaluate the prevalence of fever in the first 48 h after cardiac arrest and its effect on outcomes.

Methods

Review of patients treated between 1/1/2005 and 6/30/2010. Fever was defined as T ≥ 38.0 °C. We classified categories of post-cardiac arrest illness severity as (I) awake, (II) coma + mild cardiopulmonary dysfunction (SOFA cardiac + respiratory score <4), (III) coma + moderate-severe cardiopulmonary dysfunction, and (IV) deep coma. Associations between fever and survival or good neurologic outcome were examined between hypothermia (TH) and non-TH groups.

Results

In 336 patients, mean age was 60 years (SD 16), 63% experienced out-of-hospital cardiac arrest and 65% received TH. A shockable rhythm was present in 40%. Post arrest illness severity was category II in 38%, category III in 20%, and category IV in 42%. Fever was present in 42% of subjects, with a post-arrest median onset of 15 h in the non-TH cohort and 36 h in TH cohort. Fever was not associated with survival within the whole cohort (OR 0.32, CI 0.15, 0.68) or TH cohort (OR 1.21, CI 0.69, 2.14), but was associated with survival in non-TH cohort (OR 0.47, CI 0.20, 1.10). Fever was not associated with good outcomes in the whole cohort (OR 0.83, CI 0.49, 1.40), TH cohort (OR 1.09, CI 0.56, 2.12) or non-TH cohort (OR 0.34, CI 0.11, 1.06).

Conclusions

The development of fever within the first 48 h after ROSC is common. Fever is associated with death in non-TH patients. TH treatment appears to mitigate this effect, perhaps by delaying fever onset.     

Systemic and microcirculatory effects of dobutamine in patients with septic shock

Purpose

The aim of this study was to characterize the cardiovascular responses to dobutamine and their predictors. Our hypotheses were that dobutamine mainly produces tachycardia and vasodilation and fails to improve the microcirculation of patients with septic shock.

Materials and Methods

Systemic hemodynamics and sublingual microcirculation were evaluated with dobutamine (0, 2.5, 5.0, and 10.0 μg kg^− 1 min^− 1) in 23 patients with septic shock.

Results

Dobutamine increased heart rate, cardiac index, and stroke volume index (SVI). Mean blood pressure was unchanged, and systemic vascular resistance decreased. Individual responses were heterogeneous. Stroke volume index increased in 52% of the patients. These patients showed lower changes in mean blood pressure (3 ± 16 mm Hg vs − 10 ± 6 mm Hg, P < .05) and higher increases in cardiac index (1.47 ± 0.93 L m^− 1 m^− 2 vs 0.20 ± 0.5 L m^− 1 m^− 2) than did nonresponders. Changes in SVI significantly correlated with echocardiographic left ventricular ejection fraction (r = 0.55). In the whole group, perfused capillary density remained unchanged (14.0 ± 4.3 mm/mm² vs 14.8 ± 3.7 mm/mm²), but improved if basal values were 12 mm/mm² or less (9.1 ± 4.3 mm/mm² vs 12.5 ± 4.8 mm/mm²).

Conclusions

Dobutamine produced variable hemodynamic effects. Systolic dysfunction was the only variable associated with increases in SVI. Finally, dobutamine only improved sublingual microcirculation when severe alterations were found at baseline.     

Neurologic outcome in comatose patients resuscitated from out-of-hospital cardiac arrest with prolonged downtime and treated with therapeutic hypothermia

Background

Previous reports have shown that prolonged duration of resuscitation efforts in out-of-hospital cardiac arrest (OHCA) is associated with poor neurologic outcome. This concept has recently been questioned with advancements in post-cardiac arrest care including the use of therapeutic hypothermia (TH). The aim of this study was to determine the rate of good neurologic outcome based on the duration of resuscitation efforts in OHCA patients treated with TH.

Methods

This prospective, observational, study was conducted between January 2008 and September 2012. Inclusion criteria consisted of adult non-traumatic OHCA patients who were comatose after return of spontaneous circulation (ROSC) and received TH. The primary endpoint was good neurologic outcome defined as a cerebral performance category score of 1 or 2. Downtime was calculated as the length of time between the patient being recognized as pulseless and ROSC.

Results

105 patients were treated with TH and 19 were excluded due to unknown downtime, leaving 86 patients for analysis. The median downtime was 18.5 (10.0–32.3) min and 33 patients (38.0%) had a good neurologic outcome. When downtime was divided into four groups (≤10 min, 11–20 min, 21–30 min, >30 min), good neurologic outcomes were 62.5%, 37%, 25%, and 21.7%, respectively (p = 0.02). However, even with downtime >20 min, 22.9% had a good neurologic outcome, and this percentage increased to 37.5% in patients with an initial shockable rhythm.

Conclusions

Although longer downtime is associated with worse outcome in OHCA patients, we found that comatose patients who have been successfully resuscitated and treated with TH have neurologically intact survival rates of 23% even with downtime >20 min.     

Outcomes of hanging-induced cardiac arrest patients who underwent therapeutic hypothermia: A multicenter retrospective cohort study

Objectives

The aim of this study was to analyze the outcomes of patients with hanging-induced cardiac arrest who underwent therapeutic hypothermia (TH).

Method

In this multicenter, retrospective registry-based study, discharged patients after out-of-hospital cardiac arrest and treatment with TH were enrolled between June 2007 and March 2013. Several prehospital and hospital variables were examined for an outcome analysis with multivariable logistic regression.

Results

A total of 964 patients who had cardiac arrest were enrolled in this study. All patients underwent TH during post-cardiac arrest care after return of spontaneous circulation (ROSC). Of all patients, 105 were assigned to the hanging group and 859 to the non-hanging group. Six patients (6%) with good neurologic outcomes (Cerebral Performance Category 1 or 2) in the hanging group at the time of discharge were found. A shorter time interval between witnessed arrest and ROSC and a Glasgow Coma Scale over 4 after ROSC are statistically significant variables of good neurologic outcomes after hanging-induced cardiac arrest treated with TH.

Conclusion

A small number of patients who underwent TH after a hanging-induced cardiac arrest provided good neurologic outcomes, and some variables influenced these outcomes.     

Sublingual microcirculation is impaired in post-cardiac arrest patients

Aim

We hypothesized that microcirculatory dysfunction, similar to that seen in sepsis, occurs in post-cardiac arrest patients and that better microcirculatory flow will be associated with improved outcome. We also assessed the association between microcirculatory dysfunction and inflammatory markers in the post-cardiac arrest state.

Methods

We prospectively evaluated the sublingual microcirculation in post-cardiac arrest patients, severe sepsis/septic shock patients, and healthy control patients using Sidestream Darkfield microscopy. Microcirculatory flow was assessed using the microcirculation flow index (MFI) at 6 and 24 h in the cardiac arrest patients, and within 6 h of emergency department admission in the sepsis and control patients.

Results

We evaluated 30 post-cardiac arrest patients, 16 severe sepsis/septic shock patients, and 9 healthy control patients. Sublingual microcirculatory blood flow was significantly impaired in post-cardiac arrest patients at 6 h (MFI 2.6 [IQR: 2–2.9]) and 24 h (2.7 [IQR: 2.3–2.9]) compared to controls (3.0 [IQR: 2.9–3.0]; p < 0.01 and 0.02, respectively). After adjustment for initial APACHE II score, post-cardiac arrest patients had significantly lower MFI at 6-h compared to sepsis patients (p < 0.03). In the post-cardiac arrest group, patients with good neurologic outcome had better microcirculatory blood flow as compared to patients with poor neurologic outcome (2.9 [IQR: 2.4–3.0] vs. 2.6 [IQR: 1.9–2.8]; p < 0.03). There was a trend toward higher median MFI at 24 h in survivors vs. non-survivors (2.8 [IQR: 2.4–3.0] vs. 2.6 [IQR: 2.1–2.8] respectively; p < 0.09). We found a negative correlation between MFI-6 and vascular endothelial growth factor (VEGF) (r = −0.49, p = 0.038). However, after Bonferroni adjustment for multiple comparisons, this correlation was statistically non-significant.

Conclusion

Microcirculatory dysfunction occurs early in post-cardiac arrest patients. Better microcirculatory function at 24 h may be associated with good neurologic outcome.     

A pilot study examining the role of regional cerebral oxygen saturation monitoring as a marker of return of spontaneous circulation in shockable (VF/VT) and non-shockable (PEA/Asystole) causes of cardiac arrest

Background

Non-invasive monitoring of cerebral perfusion and oxygen delivery during cardiac arrest is not routinely utilized during cardiac arrest resuscitation. The objective of this study was to investigate the feasibility of using cerebral oximetry during cardiac arrest and to determine the relationship between regional cerebral oxygen saturation (rSO2) with return of spontaneous circulation (ROSC) in shockable (VF/VT) and non-shockable (PEA/asystole) types of cardiac arrest.

Methods

Cerebral oximetry was applied to 50 in-hospital and out-of-hospital cardiac arrest patients.

Results

Overall, 52% (n = 26) achieved ROSC and 48% (n = 24) did not achieve ROSC. There was a significant difference in mean ± SD rSO2% in patients who achieved ROSC compared to those who did not (47.2 ± 10.7% vs. 31.7 ± 12.8%, p < 0.0001). This difference was observed during asystole (median rSO2 (IQR) ROSC versus no ROSC: 45.0% (35.1–48.8) vs. 24.9% (20.5–32.9), p < 0.002) and PEA (50.6% (46.7–57.5) vs. 31.6% (18.8–43.3), p = 0.02), but not in the VF/VT subgroup (43.7% (41.1–54.7) vs. 42.8% (34.9–45.0), p = 0.63). Furthermore, it was noted that no subjects with a mean rSO2 < 30% achieved ROSC.

Conclusions

Cerebral oximetry may have a role as a real-time, non-invasive predictor of ROSC during cardiac arrest. The main utility of rSO2 in determining ROSC appears to apply to asystole and PEA subgroups of cardiac arrest, rather than VF/VT. This observation may reflect the different physiological factors involved in recovery from PEA/asytole compared to VF/VT. Whereas in VF/VT, successful defibrillation is of prime importance, however in PEA and asytole achieving ROSC is more likely to be related to the quality of oxygen delivery. Furthermore, a persistently low rSO2 <30% in spite of optimal resuscitation methods may indicate futility of resuscitation efforts.     

A history of smoking is associated with improved survival in patients treated with mild therapeutic hypothermia following cardiac arrest

Objectives

To assess the association between smoking and survival with a good neurologic outcome in patients following cardiac arrest treated with mild therapeutic hypothermia (TH).

Methods

We conducted a retrospective observational study of a prospectively collected cohort of 188 consecutive patients following cardiac arrest treated with TH between May 2007 and January 2012. Smoking status was retrospectively collected via chart review and was classified as “ever” or “never”. Primary endpoint was survival to hospital discharge with a good neurologic outcome and was compared between smokers and nonsmokers. Logistic regression analysis was used to assess the association between smoking status and neurologic outcome at hospital discharge; adjusting for age, initial rhythm, time to return of spontaneous circulation (ROSC), bystander CPR, and time to initiation of TH.

Results

Smokers were significantly more likely to survive to hospital discharge with good neurologic outcome compared to nonsmokers (50% vs. 28%, p = 0.003). After adjusting for age, initial rhythm, time to ROSC, bystander CPR, and time to initiation of TH, a history of smoking was associated with increased odds of survival to hospital discharge with good neurologic outcome (OR 3.54, 95% CI 1.41–8.84, p = 0.007).

Conclusions

Smoking is associated with improved survival with good neurologic outcome in patients following cardiac arrest. We hypothesize that our findings reflect global ischemic conditioning caused by smoking.     

Early coronary revascularization improves 24 h survival and neurological function after ischemic cardiac arrest. A randomized animal study

Background

Survival after out-of-hospital cardiac arrest (OHCA) remains poor. Acute coronary obstruction is a major cause of OHCA. We hypothesize that early coronary reperfusion will improve 24 h-survival and neurological outcomes.

Methods

Total occlusion of the mid LAD was induced by balloon inflation in 27 pigs. After 5 min, VF was induced and left untreated for 8 min. If return of spontaneous circulation (ROSC) was achieved within 15 min (21/27 animals) of cardiopulmonary resuscitation (CPR), animals were randomized to a total of either 45 min (group A) or 4 h (group B) of LAD occlusion. Animals without ROSC after 15 min of CPR were classified as refractory VF (group C). In those pigs, CPR was continued up to 45 min of total LAD occlusion at which point reperfusion was achieved. CPR was continued until ROSC or another 10 min of CPR had been performed. Primary endpoints for groups A and B were 24-h survival and cerebral performance category (CPC). Primary endpoint for group C was ROSC before or after reperfusion.

Results

Early compared to late reperfusion improved survival (10/11 versus 4/10, p = 0.02), mean CPC (1.4 ± 0.7 versus 2.5 ± 0.6, p = 0.017), LVEF (43 ± 13 versus 32 ± 9%, p = 0.01), troponin I (37 ± 28 versus 99 ± 12, p = 0.005) and CK-MB (11 ± 4 versus 20.1 ± 5, p = 0.031) at 24-h after ROSC. ROSC was achieved in 4/6 animals only after reperfusion in group C.

Conclusions

Early reperfusion after ischemic cardiac arrest improved 24 h survival rate and neurological function. In animals with refractory VF, reperfusion was necessary to achieve ROSC.     

Time to awakening and neurologic outcome in therapeutic hypothermia-treated cardiac arrest patients

Introduction

Therapeutic hypothermia (TH) has been shown to improve outcomes in comatose Post-Cardiac Arrest Syndrome (PCAS) patients. It is unclear how long it takes these patients to regain neurologic responsiveness post-arrest. We sought to determine the duration to post-arrest awakening and factors associated with times to such responsiveness.

Methods

We performed a retrospective chart review of consecutive TH-treated PCAS patients at three hospitals participating in a US cardiac arrest registry from 2005 to 2011. We measured the time from arrest until first documentation of “awakening”, defined as following commands purposefully.

Results

We included 194 consecutive TH-treated PCAS patients; mean age was 57 ± 16 years; 59% were male; 40% had an initial shockable rhythm. Mean cooling duration was 24 ± 8 h and mean rewarming time was 14 ± 13 h. Survival to discharge was 44%, with 78% of these discharged with a good neurologic outcome. Of the 85 patients who awakened, median time to awakening was 3.2 days (IQR 2.2, 4.5) post-cardiac arrest. Median time to awakening for a patient discharged in good neurological condition was 2.8 days (IQR 2.0, 4.5) vs. 4.0 days (IQR 3.5, 7.6) for those who survived to discharge without a good neurological outcome (p = 0.035). There was no significant association between initial rhythm, renal insufficiency, paralytic use, post-arrest seizure, or location of arrest and time to awakening.

Conclusion

In TH-treated PCAS patients, time to awakening after resuscitation was highly variable and often longer than three days. Earlier awakening was associated with better neurologic status at hospital discharge.     

Methylphenidate and amantadine to stimulate reawakening in comatose patients resuscitated from cardiac arrest

Background

Despite critical-care packages including therapeutic hypothermia (TH), neurologic injury is common after cardiac arrest (CA) resuscitation. Methylphenidate and amantadine have treated coma in traumatically-brain-injured patients with mixed success, but have not been explored in post-arrest patients.

Objective

Compare the outcome of comatose post-arrest patients treated with neurostimulants to a matched cohort.

Methods

Retrospective cohort study from 6/2008 to 12/2011 in a tertiary university hospital. We included adult patients treated with methylphenidate or amantadine after resuscitation from in-hospital or out-of-hospital CA (OHCA) of any rhythm, excluding patients with traumatic/surgical etiology of arrest, terminal re-arrest within 6 h, or withdrawal of care by family within 6 h. Primary outcome was following commands; secondary outcomes included survival to hospital discharge, cerebral performance category (CPC), and modified Rankin scale (mRS). We compared characteristics and outcomes to a control cohort matched on TH and 72 h FOUR score ± 1.

Results

Of 588 patients, 8 received methylphenidate, 6 received amantadine, and 2 both. Most were female suffering OHCA with median age 61 years. All received TH and a multi-modal neurological evaluation. Initial exam revealed median GCS 6 and FOUR 7, which was unchanged at 72 h. Six patients (38%) followed commands prior to discharge at median 2.5 days (range: 1–18 days) after treatment. Patients receiving neurostimulants trended toward improved rate of following commands, survival to hospital discharge, and distribution of CPC and mRS scores.

Conclusions

Neurostimulants may be considered to stimulate wakefulness in selected post-cardiac arrest patients, but a prospective trial is needed to evaluate this therapy.     

The prognostic value of continuous amplitude-integrated electroencephalogram applied immediately after return of spontaneous circulation in therapeutic hypothermia-treated cardiac arrest patients

Introduction

The purpose of this study was to examine the prognostic value of continuous amplitude-integrated electroencephalogram (aEEG) applied immediately after return of spontaneous circulation (ROSC) in therapeutic hypothermia (TH)-treated cardiac arrest patients.

Methods

From September 2010 to August 2011, we prospectively studied comatose patients treated with TH after cardiac arrest who were monitored with aEEG. Monitoring at the forehead was applied as soon as possible after ROSC in the emergency department and continued until recovery of consciousness, death, or 72 h after ROSC. Neurological outcome was assessed with the Cerebral Performance Category (CPC) scale at hospital discharge, and good neurological outcome was defined as a CPC score of 1 or 2.

Results

A total of 55 TH-treated patients were included. Monitoring started at a median of 96 min after ROSC (interquartile range, 49–174). At discharge, 28 patients had a CPC of 1–2, and 27 patients had a CPC of 3–5. Seventeen patients had a continuous normal voltage (CNV) trace at the start of monitoring, and this voltage was strongly associated with a good outcome (16/17 [94.1%]; sensitivity and specificity of 57.1 and 96.3%, respectively). No development of a CNV trace within the recorded period accurately predicted a poor outcome (21/21 [100%]; sensitivity and specificity of 77.8 and 100%, respectively).

Conclusions

An initial CNV trace in aEEG applied to forehead immediately after ROSC is a good early predictor of a good outcome in TH-treated cardiac arrest patients. Conversely, no development of a CNV trace within 72 h is an accurate and reliable predictor of a poor outcome with a false-positive rate of 0%.     

The impact of therapeutic hypothermia as adjunctive therapy in a regional primary PCI program

Background

Therapeutic hypothermia (TH) is associated with improved neurologic outcomes in comatose survivors of out-of-hospital cardiac arrest (OHCA). There are currently limited data on the outcomes of patients presenting with resuscitated OHCA in the setting of ST-segment elevation myocardial infarction (STEMI). We conducted a retrospective study to determine the outcomes of patients treated with TH for OHCA in a large regionalized STEMI program.

Methods

Patients referred for primary PCI and TH between July 2004 and April 2011 were identified from the University of Ottawa Heart Institute STEMI database. The primary endpoint was survival to hospital discharge with sufficient neurologic recovery to enable discharge home.

Results

Among 2467 consecutive patients referred for primary PCI, we identified 50 patients treated with TH following OHCA. Forty-nine underwent PCI, of which 47 (96%) received a stent. Median door-to-balloon time was 113 min (IQR 91–151). Patients with good neurologic recovery were younger, mean 51 ± 9 years versus 64 ± 12, p < 0.001, and had higher baseline creatinine clearance, 70 ± 19 mL/min/1.73 m² versus 53 ± 23 mL/min/1.73 m², p = 0.007. The primary endpoint of survival with sufficient neurologic recovery to enable discharge home was reached in 30 patients (60%). Four survivors required levels of assistance that precluded discharge home.

Conclusions

Therapeutic hypothermia in conjunction with primary PCI is associated with a favorable neurologic outcome in the majority of STEMI patients surviving OHCA. Our results suggest that TH is an important adjunctive therapy for STEMI patients suffering OHCA.     

Testosterone related good neurologic outcome on the patients with return of spontaneous circulation after cardiac arrest: A prospective cohort study

Aim

To evaluate the gonadal hormones in patients with return of spontaneous circulation (ROSC) after cardiac arrest following prospectively good (cerebral-performance category [CPC] 1-2) and poor (CPC 3-5) neurologic outcomes.

Methods

The patients in an emergency center who had been admitted to the center's intensive care unit (ICU) after successful resuscitation following out-of-hospital cardiac arrest were prospectively identified and evaluated within the period from April 2008 to March 2011. The gonadal hormones, including progesterone, total estrogen, and testosterone, were measured and analyzed following the good and poor neurologic outcomes.

Results

A total of 142 patients were analyzed in this study. Thirty-nine (27.5%) patients had good neurologic outcomes. The gonadal hormones (progesterone, total estrogen, and testosterone) had good vs. poor neurologic outcomes of 1.039 ± 0.694 vs. 1.000 ± 0.892 ng/ml, 107.956 ± 13.163 vs. 117.060 ± 11.344 pg/ml, and 307.380 ± 33.844 vs. 189.020 ± 17.406 ng/dl, respectively. In the multiple logistic-regression analysis, the initial shockable rhythm (5.671 odds ratio [OR], 2.307-13.942 95% confidence interval [CI]), time from arrest to ROSC (0.957 OR, 0.933-0.982 95% CI), and more than 300 ng/dl of testosterone level (3.279 OR, 1.265-8.190 95% CI) were found to be related to good neurologic outcome, respectively.

Conclusion

Higher testosterone levels are related to good neurologic outcome at six months after admission in patients with spontaneous circulation after cardiac arrest. The testosterone levels may be useful prognostic tools for the postcardiac-arrest syndrome and could be used for the latter's neuroprotective treatment, but additional randomized controlled studies are needed.     

Effect of moderate hyperventilation and induced hypertension on cerebral tissue oxygenation after cardiac arrest and therapeutic hypothermia

Aim

Improving cerebral perfusion is an essential component of post-resuscitation care after cardiac arrest (CA), however precise recommendations in this setting are limited. We aimed to examine the effect of moderate hyperventilation (HV) and induced hypertension (IH) on non-invasive cerebral tissue oxygenation (SctO₂) in patients with coma after CA monitored with near-infrared spectroscopy (NIRS) during therapeutic hypothermia (TH).

Methods

Prospective pilot study including comatose patients successfully resuscitated from out-of-hospital CA treated with TH, monitored with NIRS. Dynamic changes of SctO₂ upon HV and IH were analyzed during the stable TH maintenance phase. HV was induced by decreasing PaCO₂ from ∼40 to ∼30 mmHg, at stable mean arterial blood pressure (MAP ∼ 70 mmHg). IH was obtained by increasing MAP from ∼70 to ∼90 mmHg with noradrenaline.

Results

Ten patients (mean age 69 years; mean time to ROSC 19 min) were studied. Following HV, a significant reduction of SctO₂ was observed (baseline 74.7 ± 4.3% vs. 69.0 ± 4.2% at the end of HV test, p < 0.001, paired t-test). In contrast, IH was not associated with changes in SctO₂ (baseline 73.6 ± 3.5% vs. 74.1 ± 3.8% at the end of IH test, p = 0.24).

Conclusions

Moderate hyperventilation was associated with a significant reduction in SctO₂, while increasing MAP to supra-normal levels with vasopressors had no effect on cerebral tissue oxygenation. Our study suggests that maintenance of strictly normal PaCO₂ levels and MAP targets of 70 mmHg may provide optimal cerebral perfusion during TH in comatose CA patients.     

Potassium induced cardiac standstill during conventional cardiopulmonary resuscitation in a pig model of prolonged ventricular fibrillation cardiac arrest: A feasibility study

Aim of the study

Potassium-based cardioplegia has been the gold standard for cardioprotection during cardiac surgery. We sought to evaluate the feasibility and the effects of potassium-induced cardiac standstill during conventional cardiopulmonary resuscitation (CPR) in a pig model of prolonged ventricular fibrillation (VF).

Methods

VF was induced in 20 pigs, and circulatory arrest was maintained for 14 min. Animals were then resuscitated by standard CPR. Coincident with the start of CPR, 20 ml of saline (control group) or 0.9 mequiv. kg⁻¹ of potassium chloride diluted to 20 ml (potassium group) was administered into right atrium.

Results

Administration of potassium resulted in asystole lasting for 1.0 min (0.2) in the potassium group animals. VF reappeared in all but one animal, in which wide QRS complex bradycardia followed. Restoration of spontaneous circulation (ROSC) was attained in two animals (20%) in the control group and in seven animals (70%) in the potassium group (p = 0.070). Resuscitated animals in the potassium group required fewer countershocks (3, 4 vs. 2 (1–2)), smaller doses of adrenaline (1.84, 1.84 vs. 0.94 (0.90–1.00) mg), and shorter duration of CPR (8, 10 vs. 4.0 (4.0–4.0) min) than did the control group. Potassium concentrations normalised rapidly after ROSC in both groups, and the potassium concentrations at 5 min (5.5, 6.6 vs. 6.8 (6.5–7.8) mequiv. l⁻¹) and 4 h (4.9, 5.4 vs. 5.9 (5.1–6.4) mequiv. l⁻¹) after ROSC were similar in the both groups.

Conclusion

In a pig model of untreated VF cardiac arrest for 14 min, resuscitation with potassium-induced cardiac standstill during conventional CPR was found to be feasible.