The accuracy of pulse pressure variation also can be compromised in right heart failure, decreased lung or chest wall compliance, and high respiratory rates.Similar to examining pulse pressure variation, measuring respiratory variation in inferior vena cava diameter as a measure of volume responsiveness has only been validated in patients without spontaneous breaths or arrhythmias.Measuring the effect of passive leg raises on cardiac contractility by echo appears to be the most accurate measurement of volume responsiveness, although it is also subject to limitations.History and physical can often make the diagnosis of hypovolemic shock. For patients with hemorrhagic shock, a history of trauma or recent surgery is present. For hypovolemic shock due to fluid losses, history and physical should attempt to identify possible GI, renal, skin, or third-spacing as a cause of extracellular fluid loss.Although relatively nonsensitive and nonspecific, physical exam can be helpful in determining the presence of hypovolemic shock. Physical findings suggestive of volume depletion include dry mucous membranes, decreased skin turgor, and low jugular venous distention. Tachycardia and hypotension can be seen along with decreased urinary output. Differential diagnosis
While hemorrhage is the most common cause of shock in the trauma patient, other causes of shock are to remain on the differential. Obstructive shock can occur in the setting of tension pneumothorax and cardiac tamponade. These etiologies should be uncovered in the primary survey. In the setting of head or neck trauma, an inadequate sympathetic response, or neurogenic shock, is a type of distributive shock that is caused by a decrease in peripheral vascular resistance.
Chemical & Engineering News. Vol. 100, no. 3. Regalado A (February 2022). "How Pfizer made an effective anti-covid pill". MIT Technology Review. COVID 19 Drug interaction check tool University of Liverpool