Transcript File

RESPIRATORY 221
WEEK 3
PULMONARY BLOOD FLOW
Vascular System
 Two
Systems : Each have its own
reservoir, pump and set of vessels
Circulation – low pressure, low
resistance system.
 Pulmonary
 Systemic
Circulation -
PULMONARY BLOOD FLOW
Right Vs. Left
Right
Receives deoxygenated blood
RV pumps to lungs (what is its reservoir)
Pulmonic Valve receives blood from RV marks
beginning of Pulmonary Circulation
Left
Receives oxygenated blood from lungs
through FOUR major Pulmonary veins
LV pumps to system through aortic valve. AV
marks beginning of systemic circulation
Significance of lung injury and
cardiac injury
 Lung
injury to alveoli can cause a
decrease in blood flow through the lungs
 Cardiac
injury: If the left ventricle can’t
adequately pump blood to the system, the
fluid backs up potentially in the lungs
How do we measure pressure?

Pulmonary circulation pressure measurement
requires invasive procedure.
 Pulmonary artery catheter, often referred to as
Swan-Ganz catheter, is a multiple lumen, balloon
tipped catheter inserted in the heart and pulmonary
vessels through the internal jugular vein ( pg. 113
Beechy book) . This vein provides a direct path to
the right atrium.
There is a balloon located at the distal end, which can
be inflated through a different channel inside the
catheter.
There are at least two more channels
distal channel- leading to an opening at the tip of the
catheter -proximal channel- leading to an opening
located at a number of cm back from the tip.
Pulmonary Blood Pressure
•Swan-Ganz
•Quadruple Lumen flow directed balloon tipped catheter
•Figure 6-2
Rough Schematic
What do they reflect?
 CVP (RAP) measures pressure in right
heart ( right atrium)
 PAP – measures the pressure it takes to
move blood past lungs – the resistance in
the lungs (blood pumped from Rt. Ventricle)
 PCWP – Reflects (measures) pressures in
left Heart. Catheter does not go into left
heart. Balloon is inflated and wedged, cuts
off flow from right side.

Also known as PCWP, PAWP, PAOP
Normal Measurements
– Right Heart ( rt atrium) 2-6 mmHg
 PAP – Lung – Sys. 15 – 25 mmHg,
Diastolic 8-15mmHg
 Mean PAP = 2 x Diastolic + Systolic / 3
 10-15 mmHg
 PCWP – Left Heart – 4-12 mmHg
 Cardiac Output (QT or CO) – 4-8 L/min
 Systemic Arterial – 120/80
 MAP – 2 x Diastolic + Systolic / 3 – 70105 mmHg ( 93)
 CVP
Recap
2-6
CVP
Rt
20/10
PAP
Lung
4-12
PCWP
Lt
4-8L/min
QT
System
Where is problem? Traffic Jam?
 Accident
in the pulmonary capillaries,
blood backs up, increase in CVP, increase
PAP, decrease in left PCWP or CO or Sys.
Arterial pressure
INTERPRETATIONS
CVP= pressures in the right atrium
two main factors that influence right atrial pressures are the
blood volume returning to it and the functioning of the right
ventricle.
Decreased CVP usually indicates the patient is hypovolemic.
Hypotension (LOW BP) will confirm this.
Increased CVP usually suggests one of the following
possibilities. Fluid overload- check for elevated BP and
crackles (wetness) in the bases of the lungs- this is a late
finding
Tricuspid or pulmonic valve insufficiency- will show up on
abnormal EKG and abnormal heart sounds(Murmur)
right ventricular failure- right ventricular heart attack(will
show on EKG) or patients with COPD and pulmonary
hypertension has right ventricular failure, a condition known as
Cor Pulmonale
Con’t
PAP- elevated PAP are usually found in patients with the
following conditions
1. left ventricular heart failure (CHF) or fluid overload
2. Pulmonary hypertension from COPD-(systolic PAP
exceeds 40mmHg)
3. Pulmonary hypertension from P.E systolic PAP less
than 40mmHg
 PCWP- considered “elevated” when its greater than 10mmHg
1. intravascular fluid overload- review charts for renal
failure or recent large amounts of oral or intravenous fluids
2. left ventricular dysfunction with CHF- look for hx of CHF
3. Mitral valve insuffciency- blood regurgitates back into
the left atrium shown as elevated PCWP reading.

Left Heart Issue looks like…
 If
accident in Left - PCWP increase PAP
starts to increase
CO decreased if real bad
CVP increase (really bad)
 Hypovolemia
- All pressures Low
low volume
What complication…
a COPD’er end up running into?
 Right Heart Failure
 COR PULMONALE
 Can’t exhale air trapping - distends alveolicompresses blood vessels - blood backs
up
 Right heart side failure for patients with
COPD - PAP is usually higher
 Does
Pulmonary Vascular Resistance
PVR
PVR is the resistance that vessels pose to
blood flowing through the pulmonary
circulation.
ANY FACTOR THAT INCREASES PVR
INCREASES THE WORK OF THE RIGHT
HEART
Normal = 20-200 dynes
Examples
 MEAN
PAP OF 20,
 PCWP OF 10
 CO OF 6L/M
 WHAT IS THE CALCULATED PVR ?
SO A PRESSURE OF 1.67mmHg is needed TO
PRODUCE A FLOW OF 1L/M THROUGH PULMONARY
CIRCULATION
Systemic Vascular Resistance
SVR
• SVR is the resistance that vessels pose to
blood flowing through the systemic
circulation.
• Normal = 700-1600 dynes
 SVR
= MAP – CVP
Qt
Examples
 BP
170/90 mmHg
 CVP 2 mmHg
 CO (Qt) 3
What is SVR?
To reduce PVR
 Nitric
Oxide
 Pulmonary Vasodilator
 Normal amount = ___________
 “Inhaled NO gas in extremely low
concentrations has been used
therapeutically to treat severe pulmonary
hypertension and to selectively dilate
pulmonary vessels…” –pg. 118 - 119
 Useful
in neonates with _____________
Hypoxia?








May induce increased PVR – causes
vasoconstriction
Known as HPV – low Alveolar oxygen pressure
PAO2 is less than _60 -_70__mmHg
PaO2 about 50 -60 mmHg
HPV is unique to only the pulmonary system
Keypoint: Oxygen may cause vasodialation
Curveball
Systemically, Hypoxia induces vasodilation
Pg 120
Other factors that may increase
PVR
 Acidosis
 “High
PaCO2 increases PVR…”
Acidosis - increase in carbonic acid
Corrodes pulmonary vessels
pg. 120
Clinical Focus 6-4 pg 122
Chapter 7
Gas Diffusion
 Alveolar-Air
Equation
Alveolar-Air Equation
1. Atmospheric PO2 = 760 mm Hg x 0.21 = 159 mm
Hg
2. Airway PO2 = (760 – 47) x FIO2 = 149 mm Hg
 Respiratory exchange ratio (R = 0.8)




R = VCO2/VO2
O2 consumption ≈ 250 mL/min
CO2 production ≈ 200 mL/min
Therefore,
3. Alveolar air equation

PAO2 = (760 – 47) x FIO2 – [PaCO2/0.8]
Curveball

If FIO2 > 60%, PAO2 = (760 – 47) x FIO2 – PaCO2
 Clinical
Focus 7-1 & 7-2
 Page 132 -133
Laws Governing Diffusion
Physical Gas Characteristics and Diffusion
 Graham’s Law


Henry’s Law


Gas diffusion rate is inversely proportional to the square
root of its gram molecular weight (or density); lighter gas
= faster diffusion rate
Gas diffusion is directly proportional to the gas partial
pressure (greater pressure, greater diffusion)
CO2 diffuses 20 times faster than O2 across
alveolar capillary membrane because of its much
greater solubility (it’s actually a heavier molecule)
Lung Function Using Oxygenation
Status
Two Indexes To Determine Lung Status
#1
 A-a gradient
 PAO2 – PaO2
#2
 P/F Ratio
Alveolar-Arterial Oxygen Tension
Difference (P[A-a]O2)

The P(A-a)O2 is the oxygen tension difference between
the alveoli and arterial blood.

On room air, an acceptable difference = <20mmHg
On 30%, an acceptable difference = <30mmHg
On 40%, an acceptable difference = <40mmHg
….
On 100%, an acceptable difference = <100mmHg




Example using A-a Gradient
Your patient is on a 60% venturi mask. The
PaO2 is 140mmHg. You would conclude
that:
A. The patient has an increased in A-a gradient
B. The oxygenation status of your patient is
within normal limits
C. The patient has a decreased in A-a gradient
D. The patient is hyperventilating
Are you concerned?
pH – 7.35
PaCO2 – 40 torr
PaO2 – 100 torr
HCO3 – 24 mEq/L
FIO2 – 80%
PaO2/FiO2 ratio
>400
Normal Lung Function
300-399
200-299
<200
Mild Pulmonary Disease
Moderate Pulmonary Disease
Severe/Refractory Hypoxemia
Example:
Is this normal?
PaO2 105mmHg on an FiO2 of 90%