ITE CA-2 formulas plus (from TL)

Question 1

alveolar gas equation

Answer 1

PAO2 = (Patm - PH2O) FiO2 - PaCO2/RQ Patm is the atmospheric pressure (at sea level 760 mm Hg), PH2O is partial pressure of water (approximately 45 mm Hg). FiO2 is the fraction of inspired oxygen. PaCO2 is partial pressure of carbon dioxide in alveoli (in normal physiological conditions around 40 to 45 mmHg). RQ is the respiratory quotient. The value of the RQ can vary depending upon the type of diet and metabolic state. RQ is different for carbohydrates, fats, and proteins (average value is around 0.82 for the human diet).

Question 2

formula plasma osmolarity equation

Answer 2

Plasma osmolality (Posm) = 2 x [Na] + [glucose]/18 + blood urea nitrogen/2.8

Question 3

oxygen content equation

Answer 3

OXYGEN CONTENT: CaO2 = SaO2 x Hgb x 1.34 + (PaO2 x 0.003) CaO2 = arterial oxygen content (mL/dL) SaO2 = arterial oxygen saturation **(should be 0.93-1)** Hgb = hemoglobin concentration (g/dL) PaO2 = arterial partial pressure of oxygen (mm Hg) 1.34 is used because it is the oxygen carrying capacity of hemoglobin and 0.003 is used as it is the solubility coefficient of oxygen in plasma

Question 4

oxygen delivery equation

Answer 4

OXYGEN DELIVERY: DO2 = CaO2 x CO x 10 CaO2 = arterial oxygen content CO = cardiac output (which is heart rate x stroke volume)

Question 5

formula for SVR equation

Answer 5

SVR = [80 * (MAP – RAP)] ÷ CO = [80 * (100 – 5)] ÷ 5 = 1520 dynes * sec/cm^5 Where: MAP = mean arterial pressure (mm Hg) RAP = right atrial pressure (mm Hg), central venous pressure is commonly substituted for RAP CO = cardiac output (L/min) 80 = conversion factor which changes mm Hg/L/min (Woods unit) to dynes * sec/cm^5

Question 6

formula for MAP equation

Answer 6

MAP = [(1/3) * systolic pressure] + [(2/3) * diastolic pressure] = [(1/3) * 120 mm Hg] + [(2/3) * 90 mm Hg] = 100 mm Hg

Question 7

MPAP formula equation

Answer 7

mean pulmonary arterial pressure (MPAP) must be calculated since it is not given directly: MPAP = [(1/3) * systolic pressure] + [(2/3) * diastolic pressure] = [(1/3) * 24 mm Hg] + [(2/3) * 12 mm Hg] = 16 mm Hg

Question 8

PVR formula equation

Answer 8

PVR = [80 * (MPAP – PAOP)] ÷ CO = [80 * (16 – 8)] ÷ 5 = 128 dynes * sec/cm^5 Where: MPAP = mean pulmonary arterial pressure (mm Hg) PAOP = pulmonary artery occlusion pressure or pulmonary capillary wedge pressure (mm Hg) CO = cardiac output (L/min) 80 = conversion factor which changes mm Hg/L/min (Woods unit) to dynes * sec/cm^5

Question 9

SvO2 equation

Answer 9

The Fick equation reveals SvO2 = SaO2 - [VO2 ÷ (CO * Hgb * 1.36)] Where: SvO2 = mixed venous oxygen saturation SaO2 = arterial oxygen saturation VO2 = total body oxygen consumption CO = cardiac output Hgb = hemoglobin concentration

Question 10

law and formula regarding flow equation

Answer 10

The Poiseuille Law states that: Q = ΔP(π * radius4) / (8 * viscosity * length) Where: Q = flow, Δ = change in, P = pressure, π = 3.14159… (the mathematical constant).

Question 11

CPP formula equation

Answer 11

CPP = (Aortic DBP – LVEDP)

Question 12

Respiratory system compliance equation

Answer 12

1/CRS = 1/CL + 1/CCW Where C is compliance, RS is respiratory system, L is lungs, and CW is chest wall.

Question 13

static compliance formula equation

Answer 13

CS = VT ÷ (PPL – PEEP) Where: CS is static compliance, VT is tidal volume, and PPL is plateau pressure. The static compliance of the respiratory system indicates the “stiffness” of the respiratory system, which includes the lungs and chest wall. It is determined at the end of inspiration when there is no airflow, hence “static.”

Question 14

dynamic compliance formula equation

Answer 14

CS = VT ÷ (Ppeak – PEEP) Where: CS is static compliance, VT is tidal volume, and Ppeak is peak pressure.

Question 15

Elastance formula equation

Answer 15

Elastance is the inverse of compliance: E = ΔP/ΔV.

Question 16

The standard error of the mean (SEM) can be calculated by equation

Answer 16

The standard error of the mean (SEM) can be calculated by dividing the standard deviation (SD) by the square root of the sample size (n). SEM = SD / sqrt(n)

Question 17

Power equation

Answer 17

Increasing the alpha (type I error/false-positive) will increase the power. The larger the alpha, the lower the chance of a false-negative conclusion (type II error/beta). Conversely, increasing the beta will decrease the power. Power = 1 - beta.

Question 18

Benzos in pregnancy

Answer 18

Midazolam is a benzodiazepine which should be avoided during pregnancy, especially early in pregnancy when anatomical structures are developing. Use during the third trimester is associated with floppy infant syndrome and significant neonatal withdrawal symptoms.

Question 19

Similarities in the resuscitation of adults, children (age 1 year to puberty), and infants (under one year, not including newborns):

Answer 19

Similarities in the resuscitation of adults, children (age 1 year to puberty), and infants (under one year, not including newborns): Initial assessment of the patient: check for responsiveness, breathing, and pulse (spend no more than 10 seconds to do the pulse check). For witnessed collapse, if the rescuer is alone, a mobile device may be used to activate the emergency response system (ERS) and call for an automatic external defibrillator (AED). If no mobile device is available, the rescuer may leave the patient to activate the ERS and obtain the AED. Initiate compressions as soon as possible. When only one rescuer is present, use a compression-ventilation ratio of 30:2 until an advanced airway can be obtained. The compression rate is 100-120 compressions a minute. Once an advanced airway is in place, breaths may be given once every six seconds, including during compressions.

Question 20

Differences between collapesd adults and the pediatric population (children and infants):

Answer 20

Differences between adults and the pediatric population (children and infants): In an unwitnessed collapse of an adult, proceed the same as a witnessed collapse: the rescuer may use a mobile device or leave the patient to activate the ERS and obtain an AED. However, in an unwitnessed collapse of a child or infant, the rescuer should give two minutes of CPR prior to calling or leaving to get help. Whether there are one or two rescuers, the compression-ventilation ratio without an advanced airway in adults is 30:2. If there are two rescuers in a child or infant, the compression-ventilation ratio is 15:2 instead of 30:2 (one-rescuer scenario). The compression depth for adults is at least 5 cm. In children, it is about 5 cm and at least one-third of the anterior-posterior (AP) diameter of the chest. In infants, it is about 4 cm and at least one-third of the AP diameter of the chest.

Question 21

The __________ test is used to compare data that are considered nominal (categorical) or ordinal

Answer 21

The chi-square test is used to compare data that are considered nominal (categorical) or ordinal in order to determine whether observed frequencies are significantly different from expected frequencies. Nominal data are characterized by non-ordered responses such as gender, eye color, occupation, etc. Ordinal data are characterized by ordered response categories such as pain scores, annual income ranges, etc

Question 22

Fent patch contraindications

Answer 22

Transdermal fentanyl is an excellent treatment option for chronic pain. Transdermal fentanyl is contraindicated for patients with acute pain or any pain state that requires rapid dose adjustments or any pain states that have states of pain-free intervals since the risk of respiratory depression is high.

Question 23

Incidence and risk factors of neg pressure pulm edema

Answer 23

Negative pressure pulmonary edema has an incidence of 0.05-0.1% in all general anesthetics. Risk increases to 4% if airway obstruction occurs in a spontaneously breathing patient. Other risks include young age, male gender, physical fitness, and HEENT surgery

Question 24

Bradycardia following spinal anesthetic

Answer 24

Bradycardia following spinal anesthetic injection is more common in patients with high baseline vagal tone, anesthetic levels above T5, and is associated with decreased cardiac preload Use epi early

Question 25

Brainstem ischemia may lead to apnea.

Answer 25

Brainstem ischemia may be the result of hypotension and leads to apnea.

Question 26

Cardiac acceleration fibers

Answer 26

When a sympathetic block reaches the level of T4, the sympathetic cardiac accelerating fibers begin to be blocked. The cardiac accelerating fibers originate from T1-T4 spinal nerves. When these fibers are blocked the heart rate will begin to slow. Effective treatments for bradycardia resulting from blockade of the cardiac accelerating fibers include atropine and epinephrine.

Question 27

Bainbridge reflex

Answer 27

Decreased cardiac preload can cause bradycardia as a result of decreased stretch of the myocardium. Sympathectomy following spinal anesthesia results in a decrease in systemic vascular resistance and decreased venous return. Preload in the heart causes stretch of the myocardium, which increases intrinsic activity of the heart (Bainbridge reflex). When preload falls, the intrinsic depolarization of the SA node slows resulting in another cause of bradycardia following spinal anesthesia.

Question 28

Bezold–Jarisch reflex

Answer 28

Bezold–Jarisch reflex (also called the Jarisch-Bezold reflex or Von Bezold-Jarisch) involves a variety of cardiovascular and neurological processes which cause hypopnea (excessively shallow breathing or an abnormally low respiratory rate) and bradycardia (abnormally low resting heart rate).

Question 29

What is the active metabolite of morphine and why does it matter

Answer 29

Morphine 6-glucuronide is an active metabolite of morphine which can result in respiratory depression especially in patients with impaired renal function.

Question 30

Meperidine metabolite

Answer 30

Normeperidine is a metabolite of meperidine after hepatic metabolism. Normeperidine produces CNS stimulation manifesting as myoclonus and seizures. This is particularly important in patients with impaired renal function since normeperidine can accumulate.

Question 31

What is contraindicated if recent intravitreous gas injection and for how long

Answer 31

Nitrous oxide administration should be avoided for five days after intraocular air injection, 10 days after sulfur hexafluoride injection, or 30-90 days or longer after other perfluoropropane injection. This is because of blood:gas partition coefficient differences, which allows for nitrous oxide to readily diffuse into and expand the intraocular gas bubble.

Question 32

CRPS types

Answer 32

CRPS is divided into two types. In type 1 there is no evidence of nerve damage, and in type 2 there is documented evidence of nerve damage.

Question 33

Output equation given: carrier gas ml/min vapor pressure barometric pressure

Answer 33

Output = Carrier gas X vapor pressure/barometric pressure - vapor pressure Output = 100 X 150/750-150 = approx 25 ml/min (vapor) 25 ml/min output / 5000 ml/min FGF - 0.005 or 0.5%

Question 34

How long wait after MI for for elective noncardiac surgery.

Answer 34

Remember: After an MI wait 14 days after balloon angioplasty, 30 days after BMS, 60 days if no coronary intervention, and 180 days after DES for elective noncardiac surgery.

Question 35

FeNa formula

Answer 35

[(UNa)/(UCr)]/[(PNa)/(PCr)] x 100 = [(PCr x UNa ) / (PNa x UCr)] x 100

Question 36

How to calculate what percent of gas someone is inhaling

Answer 36