SEE exam Questions Flashcards
What is placenta accreta?
adherence to the myometrium WITHOUT invasion of or passage through uterine muscle
What is placenta increta?
INVADES and is confined to the myometrium
What is placenta percreta?
INVADES and may PENETRATE the myometrium, the uterine serosa, or other pelvic structures
If mom has had a previous c-section or had uterine trauma, she is at risk for developing placenta _________.
accreta; the more c-sections the > the incidence.
Are the MRI and ultrasonography good indicators for the diagnosis of placenta accreta?
NO; they are poor
What is the MOST common indication for obstetric hysterectomy?
placenta accreta; most cases require cesarean or post partum hysterectomy without delay
What is the key anesthetic consideration for intra-op management during a case involving placenta abnormalities?
VOLUME
When is the APGAR scoring performed?
at 1 minute and again at 5 minutes
An APGAR of _______ is considered normal.
8-10
An APGAR of _______ is considered moderate distress or impairment.
4-7
An APGAR of _______ is considered to indicate need for immediate resuscitation.
0-3
How many parameters does the APGAR score include?
5
What are the 5 parameters for APGAR scores?
HR, respiratory effort, muscle tone, reflex irritability (nasal catheter, suctioning, etc), and color
How do you score an infant’s APGAR?
Either give 0, 1, or 2 on each parameter.
HR: none is 0; 100 is 2
resp effort: none is 0; irregular or shallow is 1; robust or crying is 2
muscle tone: none is 0; some flexion is 1; active movement is 2
reflex irritability: no response is 0; grimace is 1; active coughing or sneezing is 2
color: cyanotic is 0; acrocyanotic (trunk pink, ext blue) is 1; pink is 2
When is hyperreflexia seen?
in 85% of spinal cord injury patients with lesions above T5; occurs when the hypothalamus and brainstem can no longer modulate segmental spinal sympathetic nerves and thereby inhibit their output–> acute phase has diminished sympathetic activity–> sympathetic activity returning to viable cord below the lesion is isolated from upper inhibitory control
What are signs of hyperreflexia?
paroxysmal HTN, bradycardia, and cardiac dysrhythmias in response to stimulation below the level of transection (bladder cath, childbirth)
Is hyperreflexia seen immediately after injury?
No, it is not seen until the spinal shock phase has passed (usually after 2 to 3 weeks of spinal cord injury)
How do you treat autonomic hyperreflexia?
remove stimulus, deepen anesthesia, and administer direct acting vasodilators (Na nitroprusside is reliable/rapid/titratable, but continuous monitoring of cyanide toxicity; Nifedipine can be sublingual/quick onset/relatively short duration, but unreliable and delayed absorption; BEST is NICARDIPINE which is primary arterial dilator, whereas Na Nitroprusside is veno and arterial); bradycardia is treated with atropine or glyco
What happens to untreated autonomic hyperreflexia?
HTN crisis may progress to seizures, intracranial hemorrhage, or MI
What spinal lesions are usually associated with autonomic hyperreflexia?
lesions above T5 tend to be associated with AH because the majority of spinal sympathetic efferents arise below this level; below T10 are NOT associated with AH
What are some side effects seen after fasciculations caused by succinylcholine administration?
myalgia, myoglobinemia (RARE), elevated intragastric pressure, elevated ICP
When should a burn patient not receive a dose of succinylcholine?
after 24 hours following the burn
Why does fasciculation occur after administration of succinylcholine?
b\c is it a depolarizing muscle blocker; AcH-like drug binds with the nicotinic receptor at skeletal muscle nerve endings and causing depolarization
How many cervical vertebrae are there?
7
How many thoracic vertebrae are there?
12
How many lumbar vertebrae are there?
5
How many sacral vertebrae are there?
5
How many coccygeal vertebrae are there?
4
What is P50 and what is the normal #?
P50 is the partial pressure of oxygen at which Hgb is 50% saturated by oxygen; normal is 26-27mmHg
Is oxygen release from Hgb to the tissues increased or decreased by acidosis? by alkalosis?
increased by acidosis d\t curve shift to the right–> facilitates unloading of oxygen at the tissues; OPPOSITE for alkalosis
How much oxygen is dissolved in arterial blood if PaO2 is 90mmHg?
formula is: dissolved oxygen= 0.003 x PO2 (units are ml O2/100mL blood)…. so 90 x 0.003=0.270mlO2/dl
Calculate the increase in dissolved oxygen in the arterial blood if PaO2 increases from 50mmHg to 300mmHg.
dissolved O2 (PaO2, 50mmHg)= 0.003 x 50= 0.15 dissolved O2 (PaO2, 300mmHg)= 0.003 x 300= 0.90 So.... 0.90 minus 0.15= 0.75mlO2/100mL increase
Whose law permits the amount of dissolved oxygen in the blood to be calculated?
Henry’s law; gases dissolve better in colder liquids
To calculate the amount of oxygen bound to hemoglobin, you need to know:
1) amount of oxygen carried by each gram of fully saturated Hgb?
2) normal concentration of Hgb?
3) the percent saturation? 90%
1) amount of oxygen carried by each gram of fully saturated Hgb= 1.34mlO2 per g Hgb
2) normal concentration of Hgb= 15g Hgb per 100mL blood
3) the percent saturation? 90%= 90/100= 0.9
Calculate the total amount of O2 bound to Hgb when it is 90% saturated (assume normal Hgb concentration).
O2-Hgb= (1.34mlO2/gHgb) x (15g Hgb/100mL blood) x (0.9)= 18.1mLO2/100mL blood= 18.1 mL O2/dl bound
Remember that when blood is 70% and 90% saturated, respectively, the PO2 can be estimated to be at ____ and ____mmHg.
40 and 60mmHg PO2 at 70% and 90% saturation
Calculate the PO2 when blood is 90% saturated (assume normal Hgb concentration).
remember that even if you are not given PO2, you can estimate off of saturation (40 and 60 at 70% and 90%)…. so 0.003 x 60= 0.18ml O2/dl
Calculate the total amount of O2 carried by blood when it is 90% saturated (assume normal Hgb concentration).
to get the total amount carried you have to add the amount of oxygen bound to Hgb to the amount dissolved in blood: so 90% gives you PO2 of 60…. 60 x 0.003=0.18; next step is 1.34 x 15/100 x 0.9= 18.1 bound; next add 0.18 + 18.1= 18.28mL O2/100mL blood
What is the formula for blood oxygen content?
O2 content= (PaO2 x 0.003) + (Hb content[1.34] x Hg [15] x O2 saturation %)
What is the Parkland formula?
prescribes fluids based on % of body surface area burned: volume over 24 hours= kg x 4 x %BSA burned; half of this volume in first 8 hours, 25 % next 8 hours, 25 % final 8 hours
What are some common errors in the use of the t-test?
multiple application without correction; use of independent groups form for paired data and vice versa; use for ordinal data
What is the purpose of a t-test?
in independent groups: to test the difference between the means of two independent groups
in dependent samples: to test the difference between dependent, paired samples outcome
A statistical examination of two population means. A two-sample t-test examines whether two samples are different and is commonly used when the variances of two normal distributions are unknown and when an experiment uses a small sample size. For example, a t-test could be used to compare the average floor routine score of the U.S. women’s Olympic gymnastic team to the average floor routine score of China’s women’s team. –> helps determine p value
What is a dependent variable?
a DV is the object of the study, or the variable being measured
What is the difference in dependent and independent variables?
a DV is the variable being measured…. the IV is the one that affects the dependent variable and is presumed to cause or influence it
In a study of a new IV drug that may have fewer cardio effects than thiopental during induction of pediatric patients….. separated into two groups, the thiopental group and the new drug group; BP, HR and rhythm are measured by a dedicated observer who is unaware of the two groups. What are the independent and dependent variables?
The DV is the cardio parameters: BP, HR, etc
The IV is the drug, either thiopental or new drug
What positions can be used for a popliteal block?
lateral, supine, or prone
What nerve does the popliteal block cover?
sciatic
What is the landmarks for a popliteal block?
place probe in popliteal fossa and identify the nerve, popliteal vein, and popliteal artery–> at this level it is only the tibial component, but as you scan up you will see the tibial and peroneal which then join to form the sciatic
In respect to positioning, where is tibial and peroneal components of the sciatic nerve located?
tibial is medial and peroneal is lateral
When performing a popliteal block, what muscles can be seen on either side?
semitendonosis and semimembranous muscle is seen on the medial side; on the lateral side you see the biceps femoris (long and short heads)
Where does the sciatic nerve innervate?
Sciatic nerve supplies motor and sensory innervation to the posterior aspect of the thigh as well as the entire lower leg, except for medial leg … Which is supplied by the saphenous nerve (terminal branch of the femoral nerve)
* Requires adequate setup because this nerve resists local anesthetic penetration, leading to longer block onset times
Where does the sciatic nerve arise from?
Arises from the ventral rami of L4 through S3, which forms most of the sacral plexus (L4-S4)
- It is actually two nerves in close apposition, the tibial and common peroneal (fibular) nerves
- These nerves usually do not separate until the mid thigh, although separation as proximal as the pelvis occurs in about 12% of patients
- Sciatic leaves the pelvis via the greater sciatic foramen amd continues distally toward the posterior thigh between the greater trochanter and ischial tuberosity
- Although it does not inner age any muscles in the gluteal region, it supplies motor innervation to the posterior thigh muscles as well as all muscles of the leg and foot
- Provides sensory innervation to the skin of most of the leg and foot
What is the classical approach to blocking the sciatic nerve?
Labat’s sciatic nerve block: targeting it in the gluteal region; has advantage of also blocking posterior femoral cutaneous nerve, which is important when tourniquets are on for long periods
What are the landmarks for Labat’s sciatic nerve block?
- Patient is placed in lateral decubitus (operative side up) and the leg is flexed at the knee (if patient is unable to flex the knee, the leg should be extended at the hip as far as possible without discomfort)
- Draw a line between the greater trochanter to the posterior superior iliac spine (PSIS)
- Draw second line from greater trochanter to the patients sacral hiatus
- Determine the point of needle insertion by drawing a line perpendicular from the midpoint of the first line to its intersection with the second line
- A fourth line can be drawn along the “furrow” formed by the medial edge of the gluteus Maximus muscle and the long head of the biceps femoris muscle (the furrow represents the course of the sciatic nerve towards the lower leg
- The triangle formed by the 1st, 2nd, and 4th lines further defines initial needle placement, and subsequent adjustments of the needle within the triangle to improve stimulation
Where is norepinephrine synthesized?
Cytoplasm of sympathetic postganglionic nerve endings and stored in vesicles
How is the action of norepinephrine terminated?
Primarily by reputable into the postganglionic nerve terminals (which is inhibited by tricyclic antidepressants); but also by diffusion from receptor sites, or metabolism by MAO or COMT
How is norepinephrine and ultimately epinephrine synthesized?
Hydroxylation of tyrosine to dopa is the rate limiting step; norepinephrine can be converted into epinephrine in the adrenal medulla: phenylalanine to tyrosine in liver–> dopa to dopamine in postganglionic cytoplasm–> norepinephrine to epinephrine in adrenal medulla
Before how many weeks old is considered to be a premature infant?
Before 37 weeks
What is more common, omphalocele or gastroschisis?
Omphalocele ….. 1:5,000 vs 1:15,000
Where is an omphalocele located?
Base of the umbilicus
Where is a gastroschisis located?
Lateral to umbilicus
Which has a sac, omphalocele or gastroschisis?
Omphalocele
What is an important consideration with gastroschisis?
There is no sac, so prevent hypothermia, infection, and dehydration
What are some signs of Pierre Robins syndrome?
Cleft palate, small face and glottis; (less severe than treacher Collins), intubation may be difficult, use awake technique, have fully awake before extubating
What are signs of Treacher-Collins syndrome?
Small mouth, facial mouth deformity, more severe than Pierre Robin…. Difficult intubation, use awake technique, have fully awake before extubation
What is different in regards to the cardiac output of neonates and infants?
dependent on HR, since stroke volume is relatively fixed by a non-compliant and poorly developed left ventricle
How does the physiology of neonates and infants differ from adults?
CO dependent on HR, faster HR, lower BP, faster RR, lower lung compliance, greater chest wall compliance, lower FRC, higher BSA to body weight, higher total body water content
What are some anatomic differences of the neonate/infant compared to an adult?
noncompliant LV, residual fetal circulation, difficult venous and arterial cannulation, large head and tongue, narrow nasal passages, anterior and cephalad larynx, long epiglottis, short trachea and neck, prominent tonsils and adenoids, weak intercostal and diaphragm muscles, high resistance to airflow
What are some pharmacologic differences of the neonate/infant when compared to an adult?
immature hepatic biotransformation, decreased protein binding, rapid induction and recovery, increased MAC, large volume of distribution for water soluble drugs, immature neuromuscular junction
Infants are obligate __________.
nose breathers
The narrowest point of the airway in children younger than 5yo is the ___________.
crocoid cartilage
What is the formula for deciding the appropriate size ETT in pediatric patients?
4 + (age/4)= tube diameter in mm
What is the formula to calculate the appropriate ETT length in the pediatric patients?
10 + (age/2)= length in cm
Why do neonates have a more rapid induction with inhaled anesthetics?
due to a small FRC
What is the normal HR for a preterm infant? BP?
120-180; 45-60/30
What is the normal HR for a term infant? BP?
100-180; 55-70/40
What is the normal HR for a 1 year old? BP?
100-140; 70-100/60
What is the normal HR for a 3 year old? BP?
85-115; 75-110/70
What is the normal HR for a 5 year old? BP?
80-100; 80-120/70
What is the ml/kg to calculate EBV for premature infants (<term)?
90
What is the ml/kg to calculate EBV for infants (<6wk)?
80
What is the ml/kg to calculate EBV for toddlers (6wk-2yrs)?
75
What is the ml/kg to calculate EBV for a child (2y-12y)?
72
What is the ml/kg to calculate EBV for an adult male?
70
What is the ml/kg to calculate EBV for an adult female?
65
What is the 4-2-1 rule for pediatric patients?
4ml/kg for 1st 10kg, 2ml/kg between 10 and 20kg, and 1ml/kg for each kg >20
What defect in the neonate is located between the RA and LA?
foramen ovale
What defect in the neonate is located between the PA and the aorta?
ductus arteriosus
Why are infants of diabetic mothers prone to hypoglycemia?
b\c the infant will produce insulin in response to maternal blood sugar to control its own blood glucose level; after delivery of the infant, the cord is clamped eliminating maternal blood sugar level—> now the infant will have his/her own stored insulin and this insulin will decrease the newborn’s blood sugar
What is trisomy 21?
Extra chromosome, Down’s syndrome–> short neck, large tongue, mental retardation, irregular dentition, hypotonia
What is the appropriate dose for Hemabate?
aka 15-Methyl prostaglandin F2alpha; causes dose dependent increase in the force and the frequency of uterine contractions; initial recommended dose is 250mcg IM, repeat every 15 minutes up to 2mg
What is MAC-BAR?
the concentration of inhaled anesthetic that prevents adrenergic response to skin incision
What is MAC-AWAKE?
the concentration of inhaled anesthetic that inhibits appropriate responses to spoken commands in half of the patients; normal 0.35 MAC
How does temperature affect MAC?
For each 1 degree Celsius drop in temperature, MAC decreases by 5 %
What factors decrease MAC?
advanced age, hypothermia, alpha 2 agonists, acute ethanol ingestion, hypoxemia, hyponatremia, metabolic acidosis, anemia, hypotension, and pregnancy
What tissues are in the vessel rich group? How much of the CO and weight do they occupy?
brain, heart, liver, kidneys, and endocrine: 10% body weight, 75% CO
What tissues are in the muscle group? %weight? %CO?
muscle and skin; 50% weight, 19% CO
What tissues are in the fat group? %weight? %CO?
adipose tissue; 20% weight, 6% CO
What tissues are in the vessel-poor group? %weight? %CO?
teeth, hair, nails, bones, ligaments, cartilage; 20% weight, 1% CO
What is the Meyer-Overton rule?
lipid solubility of an inhalation agent is directly proportional to its potency
Which volatile agent increases CSF absorption?
isoflurane is unique in that it is the only volatile agent that facilitates CSF absorption and has favorable effect on CSF dynamics
List the following in order of MOST potent to least potent: desflurane, isoflurane, sevoflurane, and nitrous oxide.
Isoflurane is MOST—> Sevo–> Des–> nitrous
What is the basic patho of cystic fibrosis?
Hereditary disease of the exocrine glands of pulmonary and GI systems–> thick viscous secretions and decreased ciliary activity lead to PNA, wheezing, and bronchiectasis; increased residual volume and airway resistance, decreased vital capacity and expiratory flow rate
What are some anesthetic concerns following tonsillectomy and adenoidectomy?
Give preop anticholinergic to decrease secretions, use reinforced or preformed ETT, postop vomiting
If the pediatric patient becomes hypothermic in the OR, list five of the main anesthetic concerns.
1-delayed awakening 2-cardiac irritability 3-respiratory depression 4-increased pulmonary vascular resistance 5-altered drug responses
If a child unexpectedly has cardiac arrest following induction with succinylcholine, how would you immediately treat this situation?
Treat for hyperkalemia… Prolonged resuscitative efforts may be required
What is the hallmark of intra vascular fluid volume depletion in the neonate/infant?
Hypotension without tachycardia
What is a major cause of peri operative morbidity and mortality in pediatric patients?
Hypoxia from inadequate ventilation
What is the pediatric patient’s main mechanism for heat production?
Non shivering thermogenesis
A concern for paradoxical air embolism in the neonate may arise due to a ____________.
Patent foramen ovale
Up to what age is the cricoid cartilage the narrowest point of the pediatric airway?
5yo
Correct pediatric ETT placement is confirmed by ___________.
Presence of bilateral breath sounds
What is the most common type of T-E fistula?
Type IIIB
In a patient with a congenital diaphragmatic hernia, what should the peak airway pressure be?
20cmH2O
If the MAC for a neonate of an agent is 3%, how much would it be for a 1yo?
3%….. It is sevo, so the MAC is same for neonate or toddler
What are 3 common manifestations of a congenital diaphragmatic hernia?
Scaphoid abdomen, decreased breath sounds, arterial hypoxemia
Which inhalational agent has the same MAC for neonates and infants?
Sevoflurane
In the geriatric population, what changes to vagal tone and HR can be seen?
Increased vagal tone and decreased sensitivity of adrenergic receptors lead to a decline in HR; maximum HR declines by one beat per minute for every year over 50
Does the heart atrophy with age?
No! The heart does not atrophy with age—> size and tissue mass INCREASE
In regards to heart contraction, what are the elderly more dependent on?
Age related diastolic dysfunction causes the elderly to be more dependent on atrial contraction (atrial kick)
What are symptoms of diastolic dysfunction that is typically seen in the elderly?
Systemic HTN, CAD, cardiomyopathies, valvular heart disease, especially aortic stenosis
In the geriatric population, why is there a delay in the onset of IV medications but a faster induction of inhalational agents?
Due to a prolonged circulation time
What do infants and the elderly population have in common in regards to HR?
Both have a diminished ability to increase HR in response to hypovolemia, hypotension, or hypoxia
In reference to the geriatric population, what changes are seen in the following:
1-FRC
2-vital capacity
3-residual volume
4-expiratory and inspiratory reserve volumes
1-FRC increases
2-vital capacity decreases
3-residual volume increases
4-expiratory and inspiratory reserve volumes decreases
What is different in the geriatric population in regards to benzodiazepines?
Men have a slower metabolism of benzo’s, whereas elderly women metabolize benzo’s at a similar rate to that of young women
Are there any changes in plasma cholinesterase in the geriatric population?
Yes. Synthesis of plasma cholinesterase decreases in elderly men as compared to that of elderly women
What are some changes worth note in regards to epidurals and spinals in the geriatric population?
INCREASES: -Epidural volume spread increases -CSF increases -sensory block with spinals increases -spinal block duration increases -increased degeneration of peripheral nerves DECREASES: -cerebral blood flow -brain mass -nerve conduction velocity -skeletal muscle strength -gray matter -epidural segmental dosing -epidural motor block -duration of epidural action -local anesthetic doses
Why is recovery from anesthesia of inhaled anesthetics longer in the geriatric population?
Increased volume of distribution (increased body fat), decreased hepatic function (decreased halothane metabolism), decreased pulmonary gas exchange
What drug is used to treat cyanide toxicity?
cyanokit; containing the drug hydroxocobalamin
What is hydroxocobalamin?
natural form of B12; Hydroxocobalamin is used as an injectable solution for treatment of the vitamin deficiency and for treatment for cyanide poisoning; Hydroxocobalamin will bind circulating and cellular cyanide molecules to form cyanocobalamin which is excreted in the urine
What is the treatment regime for cyanide poisoning involving Sodium Nitroprusside?
- Discontinuing sodium nitroprusside administration
- Buffering the cyanide by using sodium nitrite to convert -haemoglobin to methaemoglobin as much as the patient can safely tolerate
- Infusing sodium thiosulfate to convert the cyanide to thiocyanate.
- Haemodialysis is ineffective for removing cyanide from the body but it can be used to remove most of the thiocyanate produced from the above procedure
How is response to non-depolarizing and depolarizing muscle relaxers different in the geriatric population?
Response is unaltered, except for maybe an increased onset due to prolonged circulation time; if prolonged onset… Can also be due to low skeletal muscle blood flow
A patient in pre-op has gastric reflux present and you decide to give an H2 blocker (ranitidine)… How does this drug help the patient’s situation before surgery?
It does NOTHING for the gastric contents already present….. but H2 blockers reduce gastric volume and pH after administration
What are the benefits of administering Metoclopramide?
speeds gastric emptying, decreases gastric fluid volume, increases lower esophagealsphincter tone (LES)
What happens to FRC during pregnancy?
diaphragm is displaced cephalad about 4cm by the expanding uterus–> decreases FRC by 20%; total lung capacity, vital capacity, and inspiratory capacity are NOT changed
Would you anticipate PaO2 to be higher in the pregnant or non-pregnant state?
pregnant
Would you expect PaCO2 to be higher in the pregnant or non-pregnant state?
non-pregnant
What happens to tidal volume of a pregnant patient at term?
increases by 45%
What happens to FRC of a pregnant patient at term?
decreases by 20%; this also means greater risk of hypoxemia
What happens to oxygen consumption of a pregnant patient at term?
increases by 20%
What happens to MAC in a pregnant patient at term?
MAC decreases (by 15-40%) d\t decreased FRC that results in a faster induction
What is the % change in blood volume, plasma volume, and CO in the at term parturient?
blood volume increases by 45% at term
plasma volume increases by 55% at term
CO increases by 50% at term
When is cardiac output the greatest in the parturient?
CO increases 30-40% in 1st trimester due to an increased HR and decrease in afterload (decreased SVR) while stroke volume remains same; CO is greatest after delivery for the next couple of weeks
What % change in CO is seen at each of the following stages in the parturient:
1) Latent phase
2) Active phase
3) Second stage
4) Postpartum
1) Latent phase +15%
2) Active phase +30%
3) Second stage +45%
4) Postpartum +80%
What is a possible cause for a high hemoglobin level in the parturient?
high Hgb (>14) indicates a low volume state caused by pre-eclampsia, HTN, or inappropriate diuretics
What are some GI concerns in the term parturient?
prolonged gastric emptying time and decreased LES tone (these are all due to elevated levels of circulating progesterone)
What is the first stage of labor and what dermatomes are involved?
results from uterine contraction and cervical dilation; pain initially at d. T11-12, then progresses to T10-T12 and L1 during active labor
What is the second stage of labor and what dermatomes are involved?
occurs from end of dilation until delivery of baby is completed; onset of PERINEAL pain at end of first stage is signal of fetal descent and beginning of SECOND stage; sensory innervation to perineum is provided by the pudendal nerve (S2-4), therefore the second stage of labor pain involved T10-S4 dermatomes
What is the third stage of labor?
from delivery of the baby until the placenta and membranes are expelled
What is the formula to calculate Aa-gradient?
remember it is alveolar O2 minus arterial O2; to find alveolar O2, which is room air: [150-1.25(PCO2)] - paO2; another way to do it is: PAO2= (150mmHg) - (PaCO2/0.8)
What is the difference in hypoxia and hypoxemia?
hypoxia is when a specific part (regional) of the body doesn’t receive adequate oxygen for aerobic metabolism; hypoxemia is the reduction of concentration of oxygen in arterial blood
What does the A-a gradient tell us?
measure of the difficulty oxygen has at crossing the alveolar capillary membrane
What is the A-a gradient in the following:
pH=7.53
PaCO2=26
PaO2=41
150-26/0.8= 118, then 118-41= 77… so the A-a gradient is 77
What is the formula for anion gap calculation?
(Na + K - (Cl+HCO3))
What is the formula to estimate the mEq of Bicarbonate to be replaced?
0.4 x kg x (24 - pt HCO3 from ABG)
What is the formula to calculate total oxygen content?
CaO2= (Hgb x 1.34 x SaO2) + (PaO2 x 0.003)
need ABG for PaO2
first () is the amount combined with Hgb
second () is amount dissolved in plasma
