CCP Fall 2013 - Week 1

The volume of a gas is inversely proportional to the pressure under constant temperature (Boyle's Balloon)

• Air in the middle ear        
• Eustachian tube gets clogged        
• Descent problem

• ·        
• Air trapped beneath dental work          
• Ascent problem  
•   Air expands due to barometric PSI, exerts
• pressure on nerve & dental cap or work  
•   Slow your ascent  
•   Analgesics

• Air trapped in the sinuses        
• Ascent problem  
• Slow ascent  
• Nasal decongestant  
• Analgesic

Gas trapped in tissue suddenly released

• Heavy/Obese pt w/lots of adipose tissue
• Large amount of N released during ascent 
• Pt can’t blow it off fast enough
• N bubbles form in bloodstream (The Bends)

• PreOxygenate all obese pts w/100% O₂
• Pressure gradient results – Hyperoxygenation
• results in N getting washed out of lungs (100% O₂ = 0% N inspired), 
• High N pressure gradient in bloodstream,
• N moves to lungs and is exhaled

• At a constant pressure, the volume of gas is directly proportional to the absolute temperature of the gas
• “Heat a gas and it’s volume will expand if it can, cool it back down and it’s volume will contract”
• Charles – centigrade – volume

100 m altitude increase = 1° C drop

• At a constant temp, the amt of a given gas dissolved in a liquid is directly proportional to the partial pressure of that gas in equilibrium with that liquid  
• Henry’s Heineken
• C_x = (P_x)(k)

• Charles’ gay brother
• Same as Charles law only in a vessel with a fixed size
• Directly proportional relationship btn temp & pressure
• P1/T1=P2/T2
• Temp ↑, PSI ↑; Temp ↓, PSI ↓

The pressure that a gas, in a mixture of gases, would exert if it alone occupied the whole volume occupied by the mixture

The diffusion rate of a gas through a liquid medium is directly related to the solubility of the gas & inversely proportional to the sq rt of its density

• Maximize alveolar surface area, Minimize diffusion distance through removing as much edema as possible 
• Surface Area
• Diffusion Gradient
• Diffusion distance
• Molecular size
• Solubility

• Total Pressure = Sum of the Partial Pressures of all the Gases
• Dalton’s Gang

• DEATH:
• D-drugs
•   OTCs count too
• E-exhaustion
•   Predisposes you to spatial disorientation
• A-alcohol
• T-tobacco
•   Night vision lost @ 5,000’
•   Tobacco use = lose 4,000’ 
•   Periphery is your rods, night vision 
•   CoHb affects retina swiftly
• H-hypoglycemia

Mean Sea Level

Above Ground Level

• Atmosphere
• @ sea level, the weight of a one square inch column of air extending to the edge of space is called “one atmosphere”. This refers to atmospheric pressure.
• 1 ATM weighs 14.7 psi or (760 mmHg [torr])
• Atmosphere increase w/every 33’ of depth below water, atmosphere decreases to 0.5 ATM or 380 mmHG @ 18,000’
• Atmosphere is 250k’ to 300k’        
• Atmosphere is non-uniform in density
• Perfect Day: 59°F

measurement of pressure in mmHg

measurement of pressure in pounds per sq inch

Sea level to 10,000’

10,000' to 50,000’

50,000' to 250,000'

250,000’

• Deficiency in alveolar O₂ exchange (aka altitude hypoxia)
• Any drop in available PO₂
• Apnea
• Altitude
• Venous mixing

• A failure of the tissue’s ability to use O₂ presented. Commonly a result of poisoning or metabolic disorders.
• Ex: Cyanide

• Reduction in the O₂ carrying capacity of the blood
• Hemorrhage
• Anemias: Ex. Sickle cell
• CO poisoning

• Slightly ↑ HR & RR 
• ↓ Night vision

↓ BP & ↓ Task performance (esp multitasking)

• Dizziness
• Sleepiness
• Tunnel vision
• Cyanosis

• Marked mental confusion & incapacitation
• Seizure / Coma / Death

PaO₂ ↓ ~5mmHg/1000’ ↑ in altitude

• The amount of time a FCM is able to perform useful flying duties in an inadequately oxygenated environment
• Minutes to hours to days

The elapsed time from exposure to oxygen deprived environment to point where deliberate function is lost

Explosive & Controlled

In an Explosive Decompression, Time of Useful Consciousness is ~ ½ that of Controlled Decompression

A compound of of adenosine containing 3 phosphoric acid groups. Its chemical formula is C₁₀H₁₆N₅O₁₃P₃. ATP is present in all cells & is formed when energy is released from food molecules during cell respiration. Cells contain enzymes to hydrolyze ATP into ADP, phosphate & energy, which is then available for cellular functions such as mitosis

A compound of adenosine containing 2 phosphoric acid groups. ADP is used to synthesize ATP w/the energy released in cell respiration. When ATP is used for cellular functions, such as protein synthesis, ADP is reformed.

A substance formed by condensation of adenosine & phosphoric acid. It is one of the hydrolytic products of nucleic acids & is present in muscle, RBCs, yeast & other nuclear material.

A nucleotide containing adenine & ribose. Also pharmacological agent used to block cardiac conduction through the AV node.

• Fraction of inspired O₂ 
• The conc’n of O₂ in the inspired air, esp. that supplied as supplemental O₂ by mask or catheter.

The partial pressure in arterial blood; arterial O₂ conc’n, or tension; usually expressed in mmHg

The difference btn PaO₂ & PAO₂ is the Aa Gradient – should be small in most pts but can expand.

Partial pressure of ALVEOLAR O₂

Partial pressure of venous O_2. Symbol for partial pressure of O₂ in  mixed venous blood.

Arterial Saturation of O_2. % of arterial hemoglobin saturated w/O₂

The difference btn SaO₂ & SpO₂ is generally the measuring hardware – SaO₂ uses art line co-oximeter, SpO₂ uses infrared wavelength. When there are differences in readings, susp Methemoglobin & Methemoglobinemia & CO intoxication

Any of the gases present in blood. Operationally & clinically, ABGs include the determination of levels of pH, O₂, & CO₂ in the blood.

38

2 or 3

• FiO₂
• Adequate Hemoglobin
• Cardiac Output – The ability to move hemoglobin & O₂
• Ability to extract O₂ from hemoglobin
• Ability for cells to use O₂

Lactate level

1 mmol/L ± 0.5

2.0 mmol/L

CO₂ + H₂O ⇋ H₂CO₃ ⇋ H⁺ + HCO₃^-

The effect of an acid environment on hemoglobin; H⁺ ions alter the structure of Hgb & ↑ the release of O₂. It is esp. important in active tissues producing CO₂ & lactic acid.

• HoLds O₂
• aLkolosis
• Low temp
• Low 2-3DPG
• Lots of CO

• Releases O₂
• Raised acidosis
• Raised Temp
• Raised 2-3DPG
• Reduced Oxygenation

20 : 1

Primarily in the blood, lungs & kidneys

Kidneys

2.5 L

ETCO₂ should be slightly lower than PaCO₂ (otherwise there wouldn't be a conc'n gradient to drive the diffusion of CO₂ into the alveoli)

• CO₂ production must occur at the tissue level & diffuse to the blood following a conc’n gradient
• Cardiac output must be high enough to carry the blood to the lungs from the tissue
• CO₂ must diffuse from the blood to the alveoli following a conc’n gradient
• Tidal Volume (Vt) & ultimately alveolar volume (VA) must move the CO₂ to the ETCO₂ sensor inlet

PaCO₂ Δ of 10 mmHg will cause a pH Δ of 0.08 ⇅

• Protein buffer system
• Phosphate buffer system

Potassium (K⁺)

Sodium (Na⁺)

• The more acidic the blood, the greater the amount of H⁺. The more H⁺ in the ICF, electrical polarity forces K⁺ out to the Interstitial Fluid (ISF). The Law of Mass Action results in a K⁺ shift into the blood, Lab samples will show a hyperkalemia.
• The inverse of this holds true.

• For every Δ in pH of 0.1, we will see a Δ K+ of 0.06 ⇅
• For every Δ in PaCO₂ of 10 torr, we will see a Δ in K⁺ of 0.5 mEq/L

• CaCl (raises the action potential)
• NaHCO₃^- (raise the pH, electrical gradient manipulated)
• D50 (K⁺ follows the D50)
• Insulin (Helps sugar into the cell; for every amp D50 give 5-10 u of insulin)
• β₂ agonist (albuterol on continous neb)

• furosemide (need functioning kidneys, foley in place)
• sodium polystyrene sulfonate (Kayexalate) (Faster than furosemide but will bind with Ca⁺, Mg⁺ & Na⁺)

• SLOWLY
• You should administer K+ typically @ 10-20 mEq/hr
• Do NOT exceed 0.5-1.0 mEq/kg/hr

7.35 - 7.45

35 - 45

22 - 26

80 - 100

> 95%

-2 - 2

7.31 - 7.41

40 - 50

22 - 26

35 - 40

70 - 75%

-2 - 2

• A “high” CO2 suggests ACIDOSIS
• A “low” CO2 suggests ALKLOSIS
• A “high” HCO3- suggests ALKALOSIS
• A “low” HCO3- suggests ACIDOSIS

For every 10 mmHg Δ in CO2, the pH will Δ 0.08 in the opposite direction

For every Δ in HCO₃^- of 10 mEq, the pH will Δ 0.15 in the same direction

Formula for calculating HCO₃^- replacement is: (kg/4) x Base Deficit = mEq of HCO3-

Sum Na⁺, Cl^- & TCO₂ (HCO₃^-)

• 8-16 (w/o K⁺)
• 10-20 (w/K⁺)

• Metabolic Acidosis
• The higher the anion gap, the worse the acidosis

• Lactic Acid
• DKA
• Renal
• Toxins

• Lactate level
• Altered LOC
• ↓ Urine Output
• Decreased Cardiac Output

• ↑ Sugar
• Spilling ketones

• ↑ BUN
• ↑ Creatinine (better)

• ETOH
• Heavy Metals

• Methanol
• Uremia
• DKA
• Paraldehyde
• Isoniazide & Iron
• Lactate
• Ethylene Glycol
• Salicylate

• GI Loss of H⁺: OG/NG Suctioning & N/V
• GI Loss of K⁺: Diarrhea

PAO₂=FiO₂(P_BAR-P_H20)-1.2(PaCO₂)

• A-a Gradient= PAO₂-PaO₂
• PAO₂ is generally held to be 101.73 torr

A calculation of > 10 torr

A calculation of > 20 torr

• Assure adequate V_A (Assess Vt & rate)
• Maximize FiO₂
• Add PEEP
• Invert I:E ratio