hemodynamics and respiratory support

perry

hemodynamics

basic measures of cardiovascular function

* arterial pressure and cardiac output

range for systolic blood pressure

90-140

range for diastolic blood pressure

60-90

range for mean arterial blood pressure

70-100

equation for mean arterial blood pressure

MAP = DP + 1/3(SP-DP)

minimum MAP needed to perfuse vital organs

60 mmHg

goal of MAP for septic shock treated with a vasopressor

65 mmHg

afterload

resistance the heart needs to overcome

main determinants of afterload

vaso-activity and viscosity of blood

preload

volume of blood entering the ventricle

increased volume leads to _____

increased stretching of myocardial fibers

decreased volume leads to _____

decreased stretching of myocardial fibers

what does Frank-starling curve look at

relationship between stroke volume and LVEDP (preload)

what is decreased CVP associated with

* hypovolemia
* venodilation

what is increased CVP associated with

* increased venous return
* right sided heart failure

normal value of CVP

* 8-12 mmHg
* 12-15 if patient is on ventilator

better markers of fluid responsiveness

passive leg raise

ultrasound of inferior vena cava

fluid bolus (500 mL crystalloid over 10-15 minutes)

cardiac output

volume of blood pumps by the heart in one minutes

cardiac index

volume of blood pumps by the heart in per minute, per meter squared of BSA

hemodynamic monitoring devices

* central venous pressure monitor
* Swan-Ganz catheter
* arterial line

central venous pressure monitor

* CVP monitoring
* med admin

Swan-Ganz catheter

* MAP
* cardiac output
* cardiac index
* pulmonary capillary wedge pressure
* CVP
* SVO2

arterial line

* real time MAP measurements
* arterial blood sampling-arterial blodo gas
* DO NOT use to admin meds

oxygenation

ability of oxygen to diffuse across alveoli into blood stream and be transported by hemoglobin

* informs on functional capacity of lungs and effectiveness of oxygen transport in the blood

PaO2

partial pressure of oxygen in arterial bloox

* normal = >70

SaO2

saturated oxygen in the arterial blood

* normal > 90%

ventilation

ability of CO2 to diffuse across alveoli out of blood stream and be expired by lungs

end tidal CO2

measures amount of expired CO2 and real time respiratory rate

oxygen therapy

increased oxygen in tidal volume and oxygenation of tissues at molecular level

room air

21 fraction of inspired O2

nasal cannula

provides a mix of room air and 100% O2

continuous positive airway pressure

for treatment of sleep apnea

* shunts open airways to prevent collapse and obstruction

biphasic positive airway pressure

* different inspiratory and expiratory pressures
* provides positive end-expiratory pressure
* improves oxygenation and ventilation

high flow nasal oxygen

* can deliver higher flow rates of oxygen and FiO2
* provides positive end-expiratory pressure
* improves oxygenation and ventilation

mechanical ventilation

used when patients are unable to maintain adequate alveolar ventilation = respiratory failure

examples of mechanical ventailation

* endotracheal tube
* tracheostomy tube