-What theoretically should happen when blood pressures are measured in the upper

ID: 128294 • Letter: #

Question

-What theoretically should happen when blood pressures are measured in the upper arm in various positions (above head, at heart level, below heart level) vs. in the lower extremity while in supine or standing? How does this relate to changes in fluid column and hydrostatic pressure?

-What are the differences between dynamic and static lung volumes? What volumes/capacities might change with disease such as hyperinflation disorders associated with COPD?

-Explain the typical mechanics of the lungs with inspiration/exhalation. What muscles and thoracic volume changes are associated with both?

Explanation / Answer

Blood pressure is commonly measured in the seated or supine position in arm will give different measurement values:

component

effect

position

Sitting will be higher as much as 5mmhg than supine position

Arm is at the level of the heart

Systolic pressure can be higher 8mmhg when a patient is in supine position

Patient back is not supported

The diastolic blood pressure may be increased by 6mmhg

Crossing the legs

May raise the systolic blood pressure by 2-8 mm hg

Arm below the level of the heart

Values will be too high

For every inch the arm is above or below the level of the heart , a 2mmhg difference will be found

Arm above the level of the heart

Values will be under estimated

Question no:2

Hydrostatic pressure in blood vessels is the pressure of the blood against the wall. It is the opposing force to oncotic pressure.

The pressure of a liquid is given by the relation:

P = hg, where

P = Pressure

h = Height of the liquid column

= Density of the liquid

g = Acceleration due to the gravity

It can be inferred that pressure is directly proportional to height. Hence, the blood pressure in human vessels depends on the height of the blood column in the body.

The height of the blood column is more at the feet than it is at the brain. Hence, the blood pressure at the feet is more than it is at the brain.

Question no:3

DIFFERENCES BETWEEN STATIC LUNG VOLUME AND DYNAMIC LUNG VOLUME

s.no

Static lung volume

Dynamic lung volume

Measures such as vital capacity, residual volume and total lung capacity are determined during one maximal inspiration and/or expiration

Dynamic volumes and capacities are determined during repetitive breathing, such as during exercise.

Lung volumes that are not affected by the rate of air movement in and out of the lungs.

Lung volumes that depend upon the rate at which air flows out of the lungs.

Evaluates the dimensional component for air movement within the pulmonary tract and impose no time limitation on the individual

Evaluates the power component of pulmonary performances during the different phases of the ventilator excursion.

Conditions causing change in static compliance invoke similar changes in dynamic compliance

Airway resistance is the only abnormality dynamic compliance change independently

Static compliance = tidal volume/ plateau pressure – PEEP

Dynamic compliance = tidal volume/ peak airway pressure – PEEP

Static compliance is measured when there is no airflow (using plateau pressure-PEEP

Dynamic compliance is measured when airflow is present (using the peak airway pressure- PEEP

Normal range of compliance in adults static= 40-60ml/cmH2O

Normal range of compliance in adults dynamic= 30-40ml/cmH2O

Question no:4

Question no:5 & 6

Breathing consists of 2 process inhalation and exhalation:

s.no

Inhalation

Exhalation

Active process

Passive process

Contraction of external intercostal muscles and relaxation and internal intercostal muscles occur

Relaxations of external intercostals muscles and contraction of internal intercostals muscles occur

Rib cages move forward and outward

Rib cages move downward and inward

Diaphragm contracts and becomes flattened

Diaphragm relaxes and becomes original dome shaped

Increase in volume of thoracic cavity

Decrease in volume of thoracic cavity

Air pressure in lungs is less than atmospheric pressure

Air pressure in lungs is higher than atmospheric pressure

Intake of oxygen into lungs

Expulsion of carbon di oxide from the lungs