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Antecedents to cardiac arrests in a teaching hospital intensive care unit
Thomas H Rozen1, Siobhan Mullane2, Melissa Kaufman2
1Alfred Hospital, Commercial Road, Melbourne, Australia.
Insights
Cardiac arrest (CA) inside the ICU shows physiological instability before the event, with most initial rhythms being non-shockable. While return of spontaneous circulation is high, in-hospital mortality exceeds 50%.
Area of Science:
- Critical Care Medicine
- Cardiology
- Intensive Care Unit (ICU) Studies
Background:
- Hospital cardiac arrests (CA) outside the intensive care unit (ICU) are associated with poor outcomes.
- Limited research exists on the antecedents of CA specifically within the ICU setting.
- Physiological instability often precedes CA events.
Purpose of the Study:
- To investigate the factors preceding cardiac arrests (CA) within the ICU.
- To characterize the clinical presentation and outcomes of CA in ICU patients.
Main Methods:
- Prospective identification of CA cases within an ICU from January 2010 to July 2012.
- Matched control group selection based on APACHE III diagnosis, score, age, gender, and ICU length of stay.
- Analysis of vital signs, laboratory values, and vasopressor use in the 12 hours preceding CA.
Main Results:
- CA occurred in 6.28 per 1000 ICU admissions.
- Prior to CA, patients exhibited increased respiratory rates, lower mean arterial and systolic blood pressure, higher central venous pressure, and lower bicarbonate levels.
- CA patients required higher doses of noradrenaline (norepinephrine).
- Two-thirds of CA events occurred within 48 hours of ICU admission.
- The majority of initial monitored rhythms were non-shock-responsive (72%).
- Return of spontaneous circulation was achieved in 80.6% of patients, with 44.4% surviving to hospital discharge.
Conclusions:
- Physiological instability and increased noradrenaline requirements are evident in the period leading up to ICU cardiac arrests.
- While return of spontaneous circulation rates are high (80%), in-hospital mortality remains a significant concern (>50%).
Background:
In hospital cardiac arrests (CA) treated with cardio-pulmonary resuscitation (CPR) outside of the intensive care unit (ICU) have poor outcomes. Most are preceded by deranged vital signs. There are, however, limited studies assessing antecedents to CAs inside the ICU.
Objectives:
To study the antecedents to, and characteristics of CAs in ICU.
Study Population:
We prospectively identified CA cases that occurred inside our ICU between January 2010 and July 2012. Controls were obtained by sequentially matching ICU patients based on APACHE III diagnosis, APACHE III score, age, gender and length of stay in ICU.
Results:
Thirty-six patients had a CA during the study period (6.28/1000 admissions). In the 12h prior to CA, index patients had higher maximum (22 breaths/min vs. 18 breaths/min, p=0.001) and minimum respiratory rates (16 breaths/min vs. 12 breaths/min, p=0.031), a lower median mean arterial pressure (65 mmHg vs. 70 mmHg, p=0.029) and systolic blood pressure (97 mmHg vs. 106 mmHg, p=0.033), a higher central venous pressure (14 cm H2O vs. 11 cm H2O, p=0.008) and a lower bicarbonate level (20.5 mmol vs. 26 mmol, p=0.018) compared to controls. CA patients also had a higher maximum dose of noradrenaline (norepinephrine) (17.5 mcg/min vs. 8.0 mcg/min, p=0.052) but there was no difference in any other levels of intensive care support. Two-thirds of CA's occurred within the first 48 h of ICU admission. The initial monitored rhythm was non-shock responsive (pulseless electrical activity, bradycardia or asystole) in 26/36 (72%). Return of spontaneous circulation was achieved in 29/36 (80.6%) patients, with 16/36 (44.4%) surviving to hospital discharge.
Conclusions:
In the period leading up to the CA inside ICU, there were signs of physiological instability and the need for higher doses of noradrenaline. Return of spontaneous circulation was achieved in 80%. However, in-hospital mortality was greater than 50%.
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