Critical Care Final

changes with altitude

• pressure decreases

• partial pressure of oxygen decreases

• gases expand

• temperature falls

Boyle’s Law

expansion

Dalton’s Law

pressure

Henry’s Law

solubility

Boyle’s Law definition

volume of gas is inversely proportional to its pressure

Boyle’s Law formula

P1/P2 = V2/V1

body adaptable up to ______ ft above sea level

10,000

Boyle’s Law can affect any body cavity or piece of equipment that has an _______ ______ _______

enclosed air space

As air heats up, volume increases, allowing molecules to spread out making air less dense

Charles’ Law

Charles’ Law formula (pressure constant)

V1/T1 = V2/T2

conditions exacerbated by hypoxia at altitude

• pneumonia

• COPD

• asthma

• pneumothorax

• CAD

• trauma, shock, blood loss

oxygen adjustment formula → FiO2 needed =

(FiO2 x BP1) / BP2

If patient on 100% O2 already →

use maximum altitude equation

max altitude equation → Min BP (max altitude) =

(initial FiO2 x BP1) / Final FiO2

rate of diffusion affected by:

• atmospheric pressure

• surface area of membrane

• thickness of membrane

*decreased pressure → decreased diffusion

Fick’s Law

Fick’s Law

primary gas law for diffusion across alveolar membrane

amount of gas that will dissolve in a solution and remain in solution is directly proportional to the pressure of the gas over a solution

Henry’s Law

Henry’s Law clinically important in

decompression sickness

change in density is directly related to change in temperature and pressure

ideal gas law

ideal gas law → PV =

nRT

correlation exists between pressure and temperature when volume is constant

P1/T1 = P2/T2

Gay-Lussac’s Law

gas diffuses from high to low concentration

Graham’s Law (of Effusion)

early signs of hypoxia

• impaired judgement

• fatigue and hypoglycemia

hypoxia timeframes

• effective performance time

• time of useful consciousness

limited timeframe during which person can function with inadequate level of oxygen

effective performance time

period between sudden oxygen deprivation at given altitude and onset of physical, mental impairment to point at which deliberate function is lost

time of useful consciousness

• individual tolerances

• method of hypoxia induction

• environment before hypoxia

• amount of exercise of person

• % O2 prior to hypoxia

• rapid cabin depressurization

variances in hypoxia timeframes

• inadequate ventilation or reduction in PO2

• lack of oxygen entering blood

• in air, result of reduced atmospheric pressure causing reduced alveolar PaO2

hypoxic hypoxia

cell’s inability to use oxygen adequately

histotoxic hypoxia

example of histotoxic hypoxia

cyanide poisoning

failure to transport oxygenated blood

stagnant hypoxia

stagnant hypoxia examples

• CHF

• blood clot

reduction in ability of blood to carry oxygen to tissues, despite oxygen’s abundance

hypemic (anemic) hypoxia

hypemic hypoxia examples

• sickle cell

• low iron

• CO poisoning

1. indifferent stage

2. compensatory stage

3. disturbance stage

4. critical stage

4 stages of hypoxia related to altitude

• minor physiological effects

• experienced between sea level - 10,000 ft

indifferent stage

• body provides short-term compensation against hypoxia effects

• experienced between 10,000 - 15,000 ft

compensatory stage

• cognitive impairment

• muscular coordination decreases

• personality manifestations

• experienced between 15,000 - 20,000

disturbance stage

• mental confusion → incapacitation → unconsciousness → death

• occurs within 3-5 minutes

• hyperventilation

• experienced between 20,000 ft and above

critical stage

hypoxia treatment

• 100% O2

• descend below 10,000 ft

1. lift

2. thrust

3. weight

4. drag

four primary forces acting on aircraft

• decrease levels of PO2

• barometric pressure changes

• thermal changes

• vibration from aircraft

• decreased humidity

• noise level

• fatigue

• gravitational forces

• third spacing

stressors of flight

loss of fluids from intravascular space into tissues

third spacing

disorders related to altitude

• barotrauma

• dysbarism

• barotitis media

• bariobariatrauma

• decompression sickness

barotrauma may cause pain in

• digestive tract

• sinuses

• teeth

• middle ear

• lungs

dysbarism causes pain in

closed cavities

barotitis media causes pain in

middle ear (eardrum rupture)

obese persons have greater nitrogen stores in fatty tissue resulting in decompression sickness

bariobariatrauma

stages of shock

1. initial

2. compensatory

3. progressive (decompensatory)

4. refractory (irreversible)

• increased lactate

• decreased blood flow to microcirculatory beds

• hypoxia develops

• cells cannot maintain homeostasis

initial stage

body uses physiologic mechanisms to maintain cellular homeostasis

compensatory stage

• occurs when underlying cause untreated

• life-threatening emergency

• requires early fluid resuscitation and vasopressor support

progressive (decompensatory) stage

• failure of compensatory mechanism

• tissues and organs die

refractory (irreversible) stage

types of neurogenic shock

• neurogenic

• anaphylactic

• SIRS, sepsis

• inflammation

• vasodilation

• increased microvascular permeability

• cellular activation

• release of mediators

• coagulopathy

SIRS progression

• neutrophils

• macrophages

• platelets

• endothelial

cellular activation

• fever

• tachycardia

• tachypnea

• AMS

• decreased urine output

SIRS symptoms

mild systemic response to (bacterial) infection or suspected infection

sepsis

sepsis with diagnosis of infection and dysfunction of one organ minimum

severe sepsis

hemodynamic instability with SIRS

septic shock

10th leading cause of death in US

sepsis

• CBG

• ABG

• lactate

• chest x-ray

• culture and sensitivity

• ct scan for abcess

sepsis assessment

• treat/eliminate underlying cause

• maximize oxygen delivery (SPO2 > 90, PaO2 > 60)

• reduce oxygen demand

• organ support

• targeted interventions

sepsis treatment

• reduce tachycardia and tachypnea

• reduce hyperthermia

• alleviate pain

• prevent shivering

• comfort measures

• mechanical ventilation

how to reduce oxygen demand

• cellular dysfunction

• organ damage

• organ hypoperfusion evident

• continued activation of inflammatory process

• activation of coagulation

• impairment of fibrinolysis

severe sepsis deterioration

• early recognition

• fluid resuscitation

• vasopressor and inotropic support

• infection control (fever control)

• immune-specific therapy

sepsis management

sepsis fluid resuscitation

volume expansion to optimize CO

• norepinephrine

• phenylephrine

• epinephrine

• vasopressin

• dopamine

sepsis vasopressor/inotropic support

1. measure lactate

2. obtain cultures

3. administer broad spectrum antibiotics

4. 30mL/kg crystalloid fro hypotension OR lactate >= 4 mmol/L

5. pressors to maintain MAP >= 65

6. re-measure lactate

7. consider cardiac compromise

8. blood products

within 1 hour of suspected sepsis

goal MAP for sepsis patients

>= 65 mmHg

MODS

multiple organ dysfunction syndrome

• potentially reversible

• >= 2 organ systems

• 50% mortality or more

• represents worsening SIRS

MODS

• organ directly affected

• pneumonia, acetaminophen OD

primary MODS

• due to injury from inflammatory mediators

• onset varies from 7-10 days

secondary MODS

• oxygen delivery

• nutrient transfer

• waste transfer

• stabilize fluid balance

functions of blood

• 55% plasma

• 45% red blood cells

• 1% leukocytes, platelets

blood components

_____ accounts for 60% of proteins

albumin

red blood cell life cycle time

120 days

____ & _____ account for majority of osmotic pressure

albumin, Na+

• hypovolemia

• anemia

• coagulopathy

• decreased hemoglobin or hematocrit

blood administration indications

processed from whole blood (2/3 of plasma removed)

*most commonly used

*increases oxygen carrying capability

packed RBC

• treat anemia

• replace blood volumes

packed RBC uses

with history of febrile reaction use

leukocyte reduced red cells or leukocyte filter

• each unit increases

  • HGB by 1 g/dl

  • HCT by 3

    • takes 4-6 hours for lab values to change

• less chance for fluid overload

Packed RBC characteristics

packed RBC volume

250-300 cc

• replace blood volume

• increase O2 carrying capacity

• danger of fluid overload & incompatibility

• deficient in some clotting factors

whole blood characteristics

• RBCs

• plasma proteins

• clotting factors

• plasma

whole blood composition

whole blood volume

500 cc

• control, prevent bleeding in platelet dysfunction, thrombocytopenia

• usually given if platelet count < 10-20,000 (danger of bleeding)

• from fresh whole blood

  • multiple donors

• expected increase of 10,000 per/unit

• measure at 1hr AND 18-24hrs post admin

platelets characteristics

platelet volume

30-60 cc (1 unit)

• rich in clotting factors

• NO platelets

• good for volume expansion to restore clotting factors

• improves coagulation, PT, and PTT

• used for DIC, liver failure

fresh frozen plasma (FFP)

FFP volume

200-300 cc (1 unit)

• cryoprecipitate

• clotting factors VIII, XIII, Von Willebrand’s factor, & fibrinogen from plasma and commercial concentrates

• prothrombin complex-prothrombin, Factors VII, IX, X and part of XI

clotting factors products

• prepared from FFP

• store for 1 year BUT must be used once thawed

clotting factors VIII, XIII, Von Willebrand’s factor, & fibrinogen from plasma and commercial concentrates

• used to correct specific clotting factor deficiencies

• may cause ABO incompatibilities

prothrombin complex-prothrombin, Factors VII, IX, X and part of XI

• physician’s orders

• assess baseline vitals

• IV access

  • large bore (18-20 gauge)

  • 2 lines if possible

• terms and check done?

prep for blood administration

max blood infusion time

4 hours

caused by leukocyte incompatibility - sudden onset (usually within first 15 minutes of blood trasnfusion)

*prevent by using leukocyte poor blood

febrile reaction to blood transfusion