Vital Signs in the ICU Flashcards
Central Venous Pressure
Should be between 5-20 cm H20, reflects adequate volume
Intracranial Pressure
The normal ICP is 5 - 15 mmHg. There is no defined set point at which treatment for intracranial hypertension should be initiated, but levels above 20mmHg are usually treated
Mean arterial pressure
MAP is considered to be the perfusion pressure seen by organs in the body.
It is believed that a MAP that is greater than 60 mmHg is enough to sustain the organs of the average person. MAP is normally between 70 to 110 mmHg[7]
If the MAP falls below this number for an appreciable time, vital organs will not get enough Oxygen perfusion, and will become ischemic.
Ventilator settings
Peak Inspiratory Pressure (PIP) Respiration Rate Peak End Expiratpry Pressure FiO2 I:E of 1:1. Tidal Volumes Plateau Pressure Pao2/Fio2 ratio minute ventilation (i.e., the volume of air inhaled and exhaled in 60 seconds)
Central venous (superior vena cava) or mixed venous oxygen saturation
y
Blood glucose
y
In/outputs
fluid intake of 2L/day
Hourly urine output
30ml/hour
Fio2
Medical patients experiencing difficulty breathing are provided with oxygen-enriched air, which means a higher-than-atmospheric FiO2. Natural air includes 20.9% oxygen, which is equivalent to FiO2 of 0.21. Oxygen-enriched air has a higher FiO2 than 0.21, up to 1.00, which means 100% oxygen.[1] FiO2 is typically maintained below 0.5 even with mechanical ventilation, to avoid oxygen toxicity.[2]
Pao2/Fio2 ratio
The ratio of partial pressure arterial oxygen and fraction of inspired oxygen, sometimes called the Carrico index, is a comparison between the oxygen level in the blood and the oxygen concentration that is breathed. This helps to determine the degree of any problems with how the lungs transfer oxygen to the blood.[4] A sample of arterial blood is collected for this test.[5] A PaO2/FiO2 ratio less than or equal to 200 mmHg is necessary for the diagnosis of acute respiratory distress syndrome by the AECC criteria.[6] The more recent Berlin criteria defines mild ARDS at a ratio of <300.
A PaO2/FiO2 ratio less than or equal to 250 mmHg is one of the minor criteria for severe community acquired pneumonia (i.e., possible indication for inpatient treatment).
A PaO2/FiO2 ratio less than or equal to 333 mmHg is one of the variables in the SMART-COP risk score for intensive respiratory or vasopressor support in community-acquired pneumonia.
Severity of ARDS and Pao2/Fio2 ratio
Mild (27% mortality risk): PaO2/FiO2>200mmHgbut = 300 mmHg, [positive end-expiratory pressure (PEEP) = 5cmH2O]
Moderate (32% mortality risk): PaO2/FiO2 >100 mmHg but < 200 mmHg. [PEEP = 5cmH2O]
Severe (45% mortality risk): PaO2/FiO2 <100 mmHg [PEEP =5 cm H2O]
Mechanical ventilation lung protective strategy
1) Low tidal volume ventilation: 6-8 mL/kg of ideal body weight.
2) PEEP: nearly all patients should have a minimum PEEP of 5 cmH2O, PEEP is increased to a plateau pressure of 30-32 cm H2O in patients with severe hypoxemia (PaO2/FiO2<200mmHg).
3) Fluid management strategies: Patients with ARDS have non-cardiogenic pulmonary edema due to vascular permeability from inflammation. A conservative fluid management strategy should therefore be pursued as long as the patient is not in shock or experiencing hypo perfusion. Effective fluid strategies can be achieved with daily diuretics, avoiding unnecessary intravenous fluids, and meticulously monitoring fluid intake/output and electrolytes if diuretics are utilized.
4) Novel therapies: Several other therapies and management strategies have been utilized in the management of ARDS such as systemic steroids [64], antioxidants [65] and prone positioning [66] to improve oxygenation. The benefits of these treatment modalities remain controversial and should be approached with caution under the direction of a physician that is an expert in the management of patients with ARDS.
5) Supportive care: Appropriate supportive measures should be given to all patients in the ICU. Maintaining adequate nutrition, sedation and pain control is paramount but often overseen. The prevention of secondary infections by maintaining aggressive hand hygiene, ventilator-associated infection preventative measures, and diligent central venous and urinary catheter care is vital. Gastric ulcers and deep venous thrombosis prophylaxis should be addressed on a case-by-case basis.
Pulse Pressure
It represents the force that the heart generates each time it contracts. If resting blood pressure is (systolic/diastolic) 120/80 millimeters of mercury (mmHg), pulse pressure is 40
Low (Narrow) Pulse Pressure
A pulse pressure is considered abnormally low if it is less than 25% of the systolic value. The most common cause of a low (narrow) pulse pressure is a drop in left ventricular stroke volume. In trauma a low or narrow pulse pressure suggests significant blood loss (insufficient preload leading to reduced cardiac output).[4]
If the pulse pressure is extremely low, i.e. 25 mmHg or less, the cause may be low stroke volume, as in Congestive Heart Failure and/or shock.
A narrow pulse pressure is also caused by aortic valve stenosis and cardiac tamponade.
High (Wide) Pulse Pressure
Usually, the resting pulse pressure in healthy adults, sitting position, is about 30-40 mmHg. The pulse pressure increases with exercise due to increased stroke volume,[5] healthy values being up to pulse pressures of about 100 mmHg, simultaneously as total peripheral resistance drops during exercise. In healthy individuals the pulse pressure will typically return to normal within about 10 minutes.
For most individuals, during aerobic exercise, the systolic pressure progressively increases while the diastolic remains about the same. In some very aerobically athletic individuals, for example distance runners, the diastolic will progressively fall as the systolic increases. This behavior facilitates a much greater increase in stroke volume and cardiac output at a lower mean arterial pressure and enables much greater aerobic capacity and physical performance. The diastolic drop reflects a much greater fall in total peripheral resistance of the muscle arterioles in response to the exercise (a greater proportion of red versus white muscle tissue). Individuals with larger BMIs due to increased muscle mass (body builders) have also been shown to have lower diastolic pressures and larger pulse pressures.[6]
