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Noninvasive hemodynamic characterization of shock and preshock using echocardiography in cardiac intensive care unit patients
Noninvasive hemodynamic characterization of shock and preshock using echocardiography in cardiac intensive care unit patients
Reviewer: Cheelim Liew and Alison White, AFASA | ASA SIG: Cardiac
Authors: Jentzer J, Burstein B, Ternus B, Bennett C, Menon V, Oh J, Anavekar N
Why the study was performed
Cardiogenic shock is a life-threatening condition associated with considerable morbidity and mortality among patients admitted to the ICU. Currently, it is difficult to distinguish the type of shock patients are enduring, with limited literature on the use of echocardiographic measurements in categorising the degree of shock. This review describes the transthoracic echocardiogram’s (TTE) characteristics for each shock classification for patients in the ICU. Clinical definitions of shock as classified in this article are summarised in the table below:
Hypotension
Presence of any of the following criteria:
Admission systolic BP < 90 mmHg
Minimum systolic BP <90 mmHg during 1st hour
Admission mean arterial pressure (MAP)< 60& mmHg
Minimum MAP < 60 mmHg during first 1 hour
Hypoperfusion
Presence of the following criteria:
Admission lactate > 2 mmol/L
Urine output < 720 ml during first 24 hours
Creatinine increased by ≥ 0.3 mg/dl during first 24 hours
Classification: NormalStudy Definition: Neither hypotension nor hypoperfusion
Classification: IsolatedStudy Definition: Hypotension without hypoperfusion
Classification: Isolated Study Definition: Hypoperfusion without hypotension
Classification: ShockStudy Definition: Both hypotension and hypoperfusion
How the study was performed
This is a retrospective study using data from 2007 to 2015 from the Mayo Clinic Cardiac Intensive Care Unit (CICU), with 5375 patients included in the study. Data was collected and analysed on patients who had a TTE performed to assess LV ejection fraction (LVEF) within 1 day of admission to the CICU. Data collected included information on patient demographics, vital signs including blood pressure, blood and urine testing data and clinical observations correlating to the shock classification. Following shock classification, echocardiographic parameters were collected. Multiple statistical analyses were conducted to identify trends in the TTE parameters of patients in each shock classification.
What the study found (TTE features)
Shock: decrease in biventricular systolic function, stroke volume (SV), increase in biventricular filling pressures
Isolated hypoperfusion: reduction in ventricular forward flow
Isolated hypotension: decrease in systematic vascular resistance
Patients with isolated hypotension (normotensive shock) have lower forward flow and higher vascular tone than those with isolated hypotension (preshock), reflecting worse underlying cardiac compromise with preserved vascular compensatory mechanisms
Relevance to clinical practice
TTE can prognostically identify the different types of shock in ICU patients.
Cardiac sonographers can utilise 2D and spectral Doppler measurements to categorise the type of shock.
Early recognition of these patients through TTE performed by the cardiac sonographers could prompt timely and appropriate interventions that could make a difference in patients’ outcomes.
