Outcome from intensive care after cardiac arrest: comparison between two patient samples treated in 1986-87 and 1999-2001 in Finnish ICUs

Mortality in out-of-hospital cardiac arrest patients has decreased in the era of therapeutic hypothermia

BACKGROUND

Mild therapeutic hypothermia (TH) improves survival after out-of-hospital cardiac arrest (OHCA). This treatment was implemented in most Finnish intensive care units (ICUs) in 2003. The aim of this study was to find out whether hospital mortality of ICU-treated OHCA patients has changed in the era of TH.

METHODS

This was a retrospective study of data collected prospectively into the database of the Finnish Intensive Care Consortium during the years 2000-2008. The study population consisted of 3958 patients for whom cardiac arrest was registered as the reason for ICU admission and who were transferred to the ICU from the emergency department. We divided the patients into those treated in the pre-hypothermia era (2000-2002) and those treated in the hypothermia era (2003-2008). We investigated whether the treatment period had any impact on hospital mortality.

RESULTS

There were no differences between the periods regarding the age or initial Glasgow Coma Scores of the patients. Mean severity of illness was higher in the latter period. Despite this, mortality decreased: the hospital mortality rate was 57.9% in 2000-2002 and 51.1% in 2003-2008, P < 0.001. In a multivariate logistic regression analysis, treatment in 2003-2008 was associated with a reduced risk of in-hospital death (adjusted odds ratio 0.54, 95% confidence interval 0.45-0.64 and P < 0.001). Survival improved markedly between the years 2002 and 2003. This improvement has persisted, but there has been no further improvement.

CONCLUSION

Concurrently with the implementation of TH, hospital mortality of OHCA patients treated in Finnish ICUs decreased.

Therapeutic hypothermia for cardiac arrest: a practical approach

Therapeutic hypothermia (TH), which prevents and ameliorates the cascade of secondary neurologic injury after the return of spontaneous circulation, is the most effective neuroprotective therapy for encephalopathic survivors of cardiac arrest. Despite the compelling efficacy of TH, most patients who survive cardiac arrest long enough to be hospitalized will nonetheless suffer a poor neurologic outcome. Attention to the details of therapy and an integrated approach involving emergency medicine, neurology, cardiology, critical care medicine, and palliative care are likely to yield the best results. This effort is complex, and broad implementation of TH has been slow in the United States and Europe. Given that most cardiac arrest mortality in patients who survive long enough to be hospitalized is due to brain injury rather than circulatory collapse, neurologists should recognize their primary role as advocates for neuroprotective therapy at all stages of the evaluation. In the emergency department, hemodynamic stabilization must be achieved and a rapid neurologic and cardiac evaluation performed, with patients efficiently triaged to hypothermia and cardiac revascularization. Cardiologists should be aware that it is safe and desirable to induce TH, even when urgent coronary angiography and percutaneous revascularization procedures are required. In the intensive care unit, cerebral perfusion must be optimized, metabolic homeostasis achieved, and neuromonitoring used during the dangerous decooling phase. Cardiac arrest is always a life-altering event for patients and their families. Even after cardiac arrest survivors have been stabilized and treated, physicians must recogonize and embrace their role in facilitating a variety of difficult transitions: to organ donation, end-of-life care, nursing or rehabilitation placement, or home.

Influence of mild therapeutic hypothermia after cardiac arrest on hospital mortality

OBJECTIVE

Following two randomized controlled trials that demonstrated reduced mortality and better neurological outcome in cardiac arrest patients, mild therapeutic hypothermia was implemented in many intensive care units. Up to now, no large observational studies have confirmed the beneficial effects of mild therapeutic hypothermia.

DESIGN

Internet-based survey combined with a retrospective, observational study.

PATIENTS

All patients admitted to an intensive care unit in The Netherlands after cardiac arrest from January 1, 1999 until January 1, 2009.

DATA SOURCE

Dutch National Intensive Care Evaluation database.

METHODS

The moment of implementation of mild therapeutic hypothermia for each hospital participating in the Dutch National Intensive Care Evaluation database was determined with an Internet survey. To compare mortality before and after implementation of mild therapeutic hypothermia, the odds ratio adjusted for Simplified Acute Physiology Score II score, age, gender, propensity score, and in- or out-of-hospital cardiac arrest was calculated. Patients were excluded if 1) they were admitted to an intensive care unit that did not respond to the survey, 2) they were admitted within 3 months after implementation of mild therapeutic hypothermia, 3) they had a Glasgow Coma Scale score of >8, or 4) they did not satisfy the Simplified Acute Physiology Score II inclusion criteria.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

A total of 13,962 patients were admitted to an intensive care unit following cardiac arrest. In total 8,645 patients were excluded, 5,544 because of a Glasgow Coma Scale score of >8. Of the resultant 5,317 patients, 1,547 patients were treated before and 3,770 patients after implementation of mild therapeutic hypothermia. Patients admitted after implementation of mild therapeutic hypothermia had lower minimal and maximal temperatures (p < .0001) during the first 24 hrs on the intensive care unit compared to patients admitted before implementation of mild therapeutic hypothermia. The adjusted odds ratio of the hospital mortality of patients treated after implementation of mild therapeutic hypothermia was 0.80 (95% confidence interval of 0.65-0.98, p = .029).

CONCLUSION

The results of this retrospective, observational survey suggest that implementation of mild therapeutic hypothermia in Dutch intensive care units is associated with a 20% relative reduction of hospital mortality in cardiac arrest patients.

Basic life support with four different compression/ventilation ratios in a pig model: the need for ventilation

BACKGROUND

During cardiac arrest the paramount goal of basic life support (BLS) is the oxygenation of vital organs. Current recommendations are to combine chest compressions with ventilation in a fixed ratio of 30:2; however the optimum compression/ventilation ratio is still debatable. In our study we compared four different compression/ventilation ratios and documented their effects on the return of spontaneous circulation (ROSC), gas exchange, cerebral tissue oxygenation and haemodynamics in a pig model.

METHODS

Study was performed on 32 pigs under general anaesthesia with endotracheal intubation. Arterial and central venous lines were inserted. For continuous cerebral tissue oxygenation a Licox PtiO(2) probe was implanted. After 3 min of cardiac arrest (ventricular fibrillation) animals were randomized to a compression/ventilation-ratio 30:2, 100:5, 100:2 or compressions-only. Subsequently 10 min BLS, Advanced Life Support (ALS) was performed (100%O(2), 3 defibrillations, 1mg adrenaline i.v.). Data were analyzed with 2-factorial ANOVA.

RESULTS

ROSC was achieved in 4/8 (30:2), 5/8 (100:5), 2/8 (100:2) and 0/8 (compr-only) pigs. During BLS, PaCO(2) increased to 55 mm Hg (30:2), 68 mm Hg (100:5; p=0.0001), 66 mm Hg (100:2; p=0.002) and 72 mm Hg (compr-only; p<0.0001). PaO(2) decreased to 58 mmg (30:2), 40 mm Hg (100:5; p=0.15), 43 mm Hg (100:2; p=0.04) and 26 mm Hg (compr-only; p<0.0001). PtiO(2) baseline values were 12.7, 12.0, 11.1 and 10.0 mm Hg and decreased to 8.1 mm Hg (30:2), 4.1 mm Hg (100:5; p=0.08), 4.3 mm Hg (100:2; p=0.04), and 4.5 mm Hg (compr-only; p=0.69).

CONCLUSIONS

During BLS, a compression/ventilation-ratio of 100:5 seems to be equivalent to 30:2, while ratios of 100:2 or compressions-only detoriate peripheral arterial oxygenation and reduce the chance for ROSC.

Therapeutic hypothermia for cardiac arrest: a practical approach

Therapeutic hypothermia (TH), which prevents and ameliorates the cascade of secondary neurologic injury after the return of spontaneous circulation, is the most effective neuroprotective therapy for encephalopathic survivors of cardiac arrest. Acute management of patients with severe hypoxic-ischemic encephalopathy requires rapid and well-coordinated efforts involving emergency medicine, neurology, cardiology, critical care medicine, and palliative care. This effort is complex, and broad implementation of TH has been slow in the United States and Europe. This review summarizes recent developments in the practical application of TH, reviews the role of the neurologist, and suggests an algorithm for coordination of care of cardiac arrest survivors by physicians of divergent subspecialties, with the goals of maximizing neurologic and cardiac recovery.