Lets Get Physical
At a constant light intensity and hemoglobin concentration, the intensity of light transmitted through a tissue is a logarithmic function of the this measurement.
What is oxygen saturation?
Two wavelengths of light are required to distinguish HbO2 from Hb. Light-emitting diodes in the pulse sensor emit red (660 nm) and near infrared (940 nm) light. The percentage of HbO2 is determined by measuring the ratio of infrared and red light sensed by a photodetector.
(Na+) - (Cl- - HCO3-) =
What is anion gap?
Normal = 8-14
Anion Gap Metabolic Acidosis: MUDPILES
This organ is the most important for metabolism of drugs.
What is the liver?
Hepatic drug clearance depends on three factors: the intrinsic ability of the liver to metabolize the drug, hepatic blood flow and the extent of binding of the drug to blood components
This type of imaging generates dynamic images by transmitting a brief pulse of high-frequency sound that propagates through tissue.
What is ultrasound/echocardiography?
The ultrasound transducer records the time delay and signal intensity for each returning reflection. Since the speed of sound in tissue is constant, the time delay allows the echo system to precisely calculate the location of cardiac structures and thereby create an image map of the heart.
[FiO2 x (barometric pressure - PH2O)] - (PaCO2/RQ) =
What is the alveolar oxygen equation (PAO2)?
Simplified version:
PAO2 = (FiO2 x 713) - (PaCO2/0.8)
These types of drugs have a rapid onset of action because they rapidly diffuse into highly perfused tissue.
What are lipophilic drugs?
They have a very short duration of action because of redistribution of drug from the CNS to the blood.
This type of monitoring uses fluid filled tubing and the transmission of force to a transducer that converts the displacement of a silicon crystal into voltage changes.
What is intra-arterial blood pressure monitoring?
These electrical signals are amplified, filtered, and displayed as the arterial pressure trace.
(140 - serum sodium) x total body water =
What is the sodium deficit?
Total body water = weight (kg) x 0.6
Example: 100 kg patient with a serum Na+ of 110 mEq/L, calculate the sodium deficit
SD = (140 - 110) x (100 x 6) = 1800 mEq
These types of anesthetics produce dose-dependent depression of EEG, SEPs and MEPs.
What are volatile anesthetics?
Other effects include:
-decrease CMRO2 while increasing CBF
-decrease arterial blood pressure, SVR and myocardial function
-decrease tidal volume, increase respiratory rate, relax airway smooth muscle, decrease ventilatory response to hypercarbia and hypoxia
Ifrared absorption spectroscopy measures this, which is necessary for anesthetic monitoring during moderate to deep sedation, as well as, general anesthesia.
What is expired carbon dioxide?
[EBV x (Hctinitial - Hctfinal)]/Hctinitial =
What is allowable blood loss?
How much blood can be lost, typically during surgery, before transfusion should be considered.
Average blood volumes:
Normal Hct Values:
Compared to Thiopental and Propofol, this IV anesthetic produces less depression of EEG activity.
What is Methohexital?
This measurement is assessed by injection of room temperature or chilled fluid near the tip of a pulmonary artery catheter (PAC).
What is thermodilution cardiac output?
Underestimation of thermodilution CO: larger volume of injectate solution, colder temperature of injectate solution
Overestimation of thermodilution CO: smaller volume of injectate solution, warmer temperature of injectate solution
(Usodium x Pcreatinine / Ucreatinine x Psodium) x 100 =
What is the fractional excretion of sodium (FENa)?
FENa <1% = Pre-renal
FENa >1% = Intrinsic (i.e. ATN)
FENa >4% = Post-renal
Cisatracurium is primarily degraded into which metabolite by Hofmann Degradation.
What is Laudanosine?
Laudanosine is a metabolite of the neuromuscular-blocking drugs atracurium and cisatracurium with potentially toxic systemic effects. It crosses the blood-brain barrier and may cause excitement and seizure activity.