critical care medicine
Shock
Diagnosis of Shock
Clinical evaluation Test result trends Diagnosis is mostly clinical, based on evidence of insufficient tissue perfusion (depressed levels of consciousness, oliguria, peripheral cyanosis) and signs of compensatory mechanisms (tachycardia, tachypnea, diaphoresis). Specific criteria include Obtundation Heart rate>100 beats/minute Respiratory rate>22 breaths/minute Hypotension (systolic blood pressure<90 mm Hg) or a 30-mm Hg fall in baseline blood pressure Urine output<0.5 mL/kg/hour Laboratory findings that support the diagnosis include Lactate>3 mmol/L (27 mg/dL) Base deficit<−4 mEq/L PaCO2<32 mm Hg (<4.26 kPa) However, none of these findings alone is diagnostic, and each is evaluated by its trend (ie, worsening or improving) and in the overall clinical context, including physical signs. Recently, near-infrared spectroscopy has been introduced as a noninvasive and rapid technique that may measure the degree of shock; however, this technique has yet to be validated on a larger scale. Recognizing the cause of shock is more important than categorizing the type. Often, the cause is obvious or can be recognized quickly based on the history and physical examination, aided by simple testing. Chest Pain (with or without dyspnea) suggests Abdominal or back pain or a tender abdomen suggests Overview of Pancreatitis , Fever, chills, and focal signs of infection suggest Sepsis and Septic Shock , particularly in immunocompromised patients. Isolated fever, contingent on history and clinical settings, may point to heatstroke. Tests include chest x-ray; urinalysis; CBC; and cultures of wounds, blood, urine, and other relevant body fluids. In a few patients, the cause is occult. Patients with no focal symptoms or signs indicative of cause should have ECG, cardiac enzyme measurement, chest x-ray, and ABGs. If results of these tests are normal, the most likely causes include drug overdose, occult infection (including Toxic Shock Syndrome (TSS) ), anaphylaxis, and obstructive shock. 8 mm Hg may indicate hypovolemia, although CVP may be greater in hypovolemic patients with preexisting pulmonary hypertension. Rapid bedside echocardiography (done by the treating physician) to assess adequacy of cardiac filling and function is being increasingly used to assess shock and overall cardiac performance (for review, Diagnosis references ). 1.Ferrada P: Image-based resuscitation of the hypotensive patient with cardiac ultrasound: an evidence-based review.J Trauma Acute Care Surg80 (3): 511–518, 2016. 2.Martin ND, Codner P, Greene W, et al: Contemporary hemodynamic monitoring, fluid responsiveness, volume optimization, and endpoints of resuscitation: an AAST critical care committee clinical consensus.Trauma Surg Acute Care Open5(1):e000411, 2020. doi: 10.1136/tsaco-2019-000411 