RTT 205 Midterm 2 (Cumulative)

.............. and ........... oppose inflation of the lungs

1. lung elastic tissue

2. surface tension

normal compliance of healthy spontaneous breathing individual

0.1 L/cmH2O

compliance of intubated mechanically ventilated patient

0.04 - 0.05 L/cmH2O

.......... law states that resistance to airflow depends on gas viscosity, gas density, the length of the diameter of the tube, and the flow rate of the gas through the airway

Poiseuille's law

During mechanical ventilation, gas viscosity and density, and tube length remain fairly constant. What can change?

diameter of airway lumen

resistance value of healthy spontaneous breathing individual

0.6 - 2.4 cmH2O/L/sec

resistance value of intubated mechanically ventilated patient

5 - 7 cmH2O/L/sec

what is one of the reasons the resistance of mechanically ventilated patients is higher than spontaneous breathing patients?

addition of ETT (endotracheal tube) adds resistance

................ pressure is the pressure difference between the airway opening and alveoli

transairway pressure (PTA)

transairway pressure abbreviation and formula

1. PTA

2. PTA = Pao - PA

.............. pressure is the pressure required to overcome the elastic recoil of the lungs and chest wall

transthoracic pressure (Pw)

transthoracic pressure abbreviation and formula

1. Pw

2. Pw = PA - Pbs

For spontaneous breathing Pw = Ppl - Pbs but during PPV the chest wall is .......... so Pw is only the pressure required to overcome the elastic recoil of the .............. Hence, Pw = ..............

1. silent

2. alveoli

3. Pw = PA - Pbs

transrespiratory pressure 2 formulas

1. Prs = PTA + Pw

transrespiratory pressure = transairway pressure + transthoracic pressure

2. Prs = (Flow X Resistance) + (Volume/compliance)

final equation of motion

PM = (Flow x Resistance) + ((Volume/compliance) + PEEP)

........... is the pressure required to maintain inflation of alveoli (aka alveolar distending pressure)

transpulmonary pressure (PL)

During PPV, Pbl = ........... Therefore, PL = .............

1. 0 mmHg

2. Palv or PA

During PPV, Pw = PL = PA (T/F?)

True

During PPV, Pw = PL = ((volume/compliance) + PEEP) (T/F?)

True

For PPV, the Pawo becomes ................ and is given the term ............

1. Pvent

2. Pm (mouth pressure)

.......... represents the sum of the resistive and distending pressure required to inflate the lungs

PM (mouth pressure)

PA = ((volume/compliance) + PEEP) (T/F?)

True

It is most valuable to measure the PA at ............ when volume is highest

end of inspiration

............. is the term used to denote the PA measured at the end of inspiration

Pplateau or Pplat

Pm = Paw + PA (T/F?)

True

How is PA determined?

at end of inspiration, Paw is zero since flow is zero, allowing for determination of PA via an inspiratory hold (PM = Paw + PA)

PM will equal PA when there is no resistive pressure created in the airways (T/F?)

True

static compliance is measured under conditions of no ............

flow

static compliance formula

CS = VT / Pplat-PEEP

resistance formula when flow is constant

Raw = ((PM - Pplat)/ flow)

what does IPPV stand for?

invasive positive pressure ventilation

what does NPPV stand for?

non-invasive positive pressure ventilation

external respiration occurs at the ............... membrane

alveolar capillary membrane

hypoxia leads to hypoxemia (T/F?)

False

hypoxemia leads to hypoxia

if external respiration is affected, then internal respiration is also affected (T/F?)

True

........... is low O2 in blood

hypoxemia

............ is low O2 in tissues

hypoxia

ECMO addresses issues with ........... respiration

external respiration

what does ECMO stand for?

extra corporeal membrane oxygenation

In .......... deoxygenated blood from the patient is passed across an artificial membrane where O2 is added and CO2 is removed

ECMO

during the .............. pump, the drop in intrathoracic pressure causes an increase in cardiac output and increased blood flow

thoracic pump (aka respiratory pump)

there is a thoracic pump effect during PPV (T/F?)

False

what is the significance of the thoracic pump?

patients who have issues with cardiac output and mechanically ventilated (PPV) are negatively impacted

........... is the amount of blood that fills the heart before it contracts

preload

.......... is one of the important determinants of cardiac output

preload

............ return is an important factor which influences preload

venous return

high preload = high cardiac output AND high venous return = high preload (T/F?)

True

blood pressure formula

blood pressure = cardiac output x systemic vascular resistance

what are the 2 effects of subatmospheric pressures transmitted throughout the the thoracic cavity during spontaneous inspiration?

1. intravascular pressure decrease

2. intracardiac pressure decease

the net effect of the subatmospheric intrathoracic pressure is an increase in ............

venous return

Intravascular pressure decrease:

1. subatmospheric pressure transmitted across the thoracic cavity causes the thin wall of the ............ to ............

2. the increase in intravascular ............ causes a drop in pressure within the ..........

3. this creates an .......... pressure gradient between the thoracic portions of ....... and .......... and the non thoracic ........ and ........

4. the pressure gradient increase the rate of .............. blood flow towards the ........... side of the heart

1. thoracic vena

2. expand

3. intravascular volume

4. thoracic vena cava

5. intravascular

6. IVC (inferior vena cava)

7. SVC (superior vena cava)

8. venous

9. right

Intracardiac pressure decrease:

1. subatmospheric pressure transmitted across the thoracic cavity causes expansion of the ............ and .............

2. expansion of the ........... leads to a drop in right ........... pressure

3. the drop in ............ increases the pressure gradient required for ......... which increases the rate of ........... blood flow towards the .......... side of the heart

1. right atrium

2. right ventricles

3. right atrium

4. right atrial pressure

5. right atrial pressure

6. venous return

7. venous

8. right

PPV increases ........... and ............ pressure. This positive pressure is transmitted to the ............. A rise in the pressure in the ......... reduces venous return to the heart

1. lung

2. intrapleural (intrathoracic)

3. intrathoracic vessels

4. vena cava

In inspiration during PPV, ............ pressures are positive

intrathoracic

During PPV, the decrease in venous return is dependent upon the .......... and ........... of the inspiratory positive pressures

1. magnitude

2. duration

what is the main concern for PPV on individuals with compromised cardiovascular systems

a drop in blood pressure

............... is the pressure gradient which determines arterial blood flow to the brain

cerebral perfusion pressure (CPP)

cerebral perfusion pressure formula

CPP = MAP - ICP

what are the 2 ways in which CPP can be decreased?

1. decrease in MAP (mean arterial pressure)

2. increase in ICP (intracranial pressure)

effects on CPP are generally only a concern with ...................

head injuries

in some instances of acute head trauma where ICP has dangerously increased, ........... is used to reduce ICP

hyperventilation

how does hyperventilation reduce ICP?

PaCO2 decreases = alters PH = vasoconstriction of cerebral blood vessels = ICP decreases

when trying to reduce ICP via hyperventilation, RR should be increased so that PaCO2 is ........... mmHg

25 - 35 mmHg

the renal effects are all in response to the drop in ...........

blood pressure

The primary response of the kidneys is a drop in .............. output because of 1. .................

2. ................

3. ................

4. ................

That all occur because of a decrease in ................

1. urine output

2. ADH release (antidiuretic hormone)

3. decrease in renal blood flow

4. atrial natriuretic factor

5. activation of renin angiotensin pathway

5. blood pressure

an additional renal response to low blood pressure is the activation of a ................ pathway which further decreases ............ to increase .............. to increase ............... pressure

1. renin angiotensin

2. urine output

3. fluid volumes

4. blood pressure

what are the effects of a decrease in blood pressure on the liver and GI tract?

1. hepatic ischemia which leads to jaundice

2. GI bleeds and ulcers

what are the 3 areas of complications of PPV on the pulmonary system?

1. barotrauma

2. gas distribution

3. pulmonary perfusion

a ............. can be caused by injury to the lung caused by overdistension due to increased volumes

barotrauma

......... law states that an increase in pressure results in an increase in volume to a point and once the elastic limit is reached, an increase in pressure no longer results in an increase in volume

Hooke's law

what happens if the elastic limit of the lung is reached and you continue to apply pressure

lung rupture is possible

during spontaneous inspiration, gas will flow first to the ............ dependent region of the lung

gravity dependent

the location of the gravity dependent regions in the lung depends on the position of the individual (T/F?)

True

in an ............ individual, the base of the lung becomes the gravity dependent region and receives more volume per breath

upright

in a ......... individual, the posterior portion of the lung is the dependent region

supine

pulmonary perfusion is higher in the .............. and ............ regions of the lung

1. base

2. posterior regions

During PPV, the gas will flow first to the gravity dependent region of the lung (T/F?)

False

to the gravity INDEPENDENT

PPV will compress the ........... capillaries which results in

1. .....................

2. .....................

3. ....................

1. pulmonary capillaries

2. increase in pulmonary vascular resistance

3. decrease in pulmonary perfusion (particularly to areas of highest ventilation)

4. increased work of right heart

PPV can contribute to a compromise in V/Q ratio (ventilation to perfusion matching) because perfusion is directed to areas with reduced ..............

ventilation

what are the 5 indications for ventilation?

1. acute respiratory failure

2. impending respiratory failure

3. prophylactic ventilatory support

4. hyperventilation therapy

5. apnea or impending respiratory arrest

what are the 2 indications for acute respiratory failure?

1. Hypercapnia (PaCO2 > 50 mmHg)

2. hypoxemia (PaO2 < 60 mmHg on FiO2 of > or = to 0.50) OR (PaO2 < 40 mmHg on any FiO2)

what are the 2 indications that a patient is approaching impending respiratory failure?

1. ABG values continue to deteriorate

2. WOB is increasing

in ................. a patient is experiencing a condition in which there is a high risk of future acute respiratory failure and ventilatory support is started to decrease WOB and minimize O2 consumption and hypoxemia (e.g. brain injury, heart muscle injury, shock, major surgery)

prophylactic ventilatory support

in .................. ventilatory support is used to manipulate PaCO2 and reduce ICP

hyperventilation therapy

what are the 4 functions of the ventilator?

1. inspiration

2. inspiration to exhalation

3. exhalation

4. exhalation to inspiration

in a pressure controller, the internal resistance of the ventilator is negligible, so Pg (driving pressure) is transmitted, undiminished to the airway opening (Pm) (T/F?)

True

In a pressure controller, Pg = Pm (T/F?)

True

how does a decrease in compliance affect pressure controller?

1. volume is decreased

2. time constant is decreased

3. rate of exponential flow decay is increased (faster)

how does an increase in resistance affect pressure controller?

1. peak initial flow rate is decreased

2. time constant is increased

3. rate of exponential flow decay is decreased (slower)

the respiratory cycle is also known as the ............. time

cycle

the ............ represents the time from beginning of inspiration of a breath until the beginning of inspiration of the subsequent breath

respiratory cycle / cycle time

the ........... ratio is used to confirm enough time is being given for the patient to exhale

I:E ratio

during spontaneous breathing the I:e is usually .......... to ...........

1. 1:3

2. 1:5

cycle time 2 formulas

1. cycle time = 60 seconds / RR

2. cycle time = Ti + Te

Ti formula

Ti = tidal volume / flow

I:E ratio formula

I:E = 1:(Te/Ti)

In a flow controller, the resistance of the ventilator is negligible (T/F?)

False

important and set very high

In a flow controller, Pg = PM (T/F?)

False

not equal

control of flow in a flow controller is achieved through .............

high internal ventilator resistance

why is Pg not equal to PM in a flow controller?

the high internal resistance of the ventilator (Rvent) prevents the Pg from being "felt" at the mouth