Table 1 Normal values (See Appendix 1)
From: Clinical review: New technologies – venturing out of the intensive care unit
Monitoring tool | Parameter | Normal values | Comments | Patient population in which the parameter is useful |
|---|---|---|---|---|
Esophageal | FTc, PV | FTc: 330–360 ms | FTc: correlates with cardiac output, and a mere change in the value in response to a fluid challenge can indicate hypovolemia [10-14] | The hemodynamically compromised |
Doppler monitor | PV (age-dependent): | PV: affected by afterload and left ventricular contractility [8] | Especially useful in patients with contraindications to invasive procedures [17] | |
20 years 90–120 cm/s; | Mostly studied in intubated, sedated patients | |||
50 years 70–100 cm/s; | ||||
70 years 50–80 cm/s | ||||
Thoracic bioimpedance | CO/CI, SV/SI, SVR/SVRI, TFC, PEP/LVET | CO correlates well (r = 0.83) with PA catheter [21] | Limited in diaphoretic patients Studies done in CHF, sepsis, trauma, emergency department patients CO correlates well (r = 0.83) with PA catheter [21] | Useful in nonintubated patients – noninvasive |
PEP/LVET reflect contractility [22-25] | ||||
End-tidal carbon dioxide | PetCO2 | 35–45 mmHg | Direct correlation (r = 0.64–0.87) [81,82] with PaCO2 [37,38] | COPD |
CO and coronary perfusion pressure surrogate [41-44] | Noninvasive ventilation | |||
>10 mmHg: Critical | <10 mmHg indicates unlikely ROSC [45] | Cardiac arrest | ||
Sublingual capnography [47-49] | SL CAP | 70 mmHg [48] | A surrogate for gastric tonometry (i.e. a marker of tissue hypoxia) | CO2 could be an earlier, more rapid indicator of shock than biomarkers |
Shock: >70 mmHg; sensitivity 73%, specificity 100%, positive predictive value 100% | ED studies lacking | |||
Lactic acid | LAC | <2.5 mmol/l | >4.0 mmol/l [53]: 98.2% specific for hospital admission from ED; 96% specific in prediciting mortality in normotensive inpatients; 87.5% specific in predicting mortality in hypotensive inpatients [55] | Shock of any cause |
C-reactive protein | CRP | <50–60 mg/l | Higher CRP level carries worse prognosis [65-67] | Sepsis |
Procalcitonin [81] | PCT | 0–0.5 ng/ml | >0.6 ng/ml is approximately 69.5% sensitive for infection [84] | Infected, septic patients |
>2.6 ng/ml: odds ratio 38.3 for septic shock [84] | ||||
Central venous oxygen saturation [61,73,74] | ScvO2 | 65–75% | A surrogate for mixed venous oxygen saturation and CI | Studies have found ScvO2 to be useful in myocardial infarction, intensive care unit, surgical, trauma, and septic/cardiogenic shock patients |
<60% indicates global tissue hypoxia, anemia, sepsis, low CO | ||||
>80% indicates venous hyperoxia, which implies a defect either in oxygen utilization or delivery [76] | ||||
Arteriovenous CO2 gradient [73] | A–V CO2 | <5 mmHg | Inversely proportional to CI | Useful for identifying delivery dependent states, and therefore adequacy of tissue perfusion |