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Core Temperature
- 36*C - 37.5*C
- 97*F - 99.5*F
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Thermogulatory Center of the Brain?
Hypothalamus
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Vital Signs:
Temperature
- Range: (oral) 37*C, 98.6*C
- heat of body
- indicates production (metab) and loss (skin)
- depends on metabolism
- lowest in early AM, highest in late afternoon
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Normal Temperatures for Healthy Adults
- Oral: 37 C, 98.6 F
- Rectal: 37.5 C, 99.5 F
- Axillary: 36.5 C, 97.6 F
- Tympanic: 37.5 C, 99.5 F
- Temporal: 34.4 C, 94 F
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Vital Signs:
Pulse
- Range: 60-100 bpm (80 on avg)
- [now: 50-90 bpm, 70 avg]
- throbbing sensation palpated over peripheral artery, auscultated by apical HR, regulated by SA node
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Vital Signs:
Respiration
- Range: 12-20 breaths per minute
- pulmonary ventilation, external and internal respiration
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Vital Signs:
Blood Pressure
- Range: ≤120/80 mm Hg
- Blood flows through the vessels of the circulatory system from areas of higher pressure to lower pressure. Resistance to blood flow is also involved.
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Overview of Circulatory System
- Two functions:
- 1) deliver oxygen, nutrients, hormones, electrolytes to calls
- (2)remove carbon dioxide from cells
- Two Divisions of Circulation:
- (1) Pulmonary: delivers blood to lungs
- (2) Systemic: delivers blood to tissues (aka. Peripheral or greater circulation)
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Components of the Circulatory System
(Heart and Blood Vessels)
- Artery: transports high pressure blood to tissues
- Arteriole: controls valves that regulate local blood flow
- Capillaries: sites of exchange
- Venules: collect blood form capillaries
- Vein: transports blood back to heart; major reservoir of blood; 6-10 times more distensible (elastic) than arteries
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What makes blood flow?
- “force that drives flow is greater than resistance to flow”
- Blood flows from the high pressure area across pressure gradient into low pressure area
- Resistance depends on vessel length, diameter, and blood viscosity
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How does blood get back to the heart?
- Negative pressure (0 to -5 mmHg) in right atrium (due to chest expansion during inspiration) “sucks” blood back into heart
- Constriction of smooth muscle in veins drive blood back to heart
- Auxiliary “venous pump: of one-way venous valves and skeletal muscle constriction
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Determinants of Cardiac Output (CO):
Equation, HR, SV, Preload, Afterload, Contractility
CO = HR X SV (avg. is 4.9 L/min)
- Heart rate (HR): (avg. 70 bpm Autonomic Nervous System (ANS)
- --HR increases by sympathetic (SNS) stimulation of beta-adrenergic receptors in SA node --HR decreases by parasympathetic (PNS) stimulating muscarinic receptors in SA node via the vagus nerve
- Stroke volume (SV): (avg 70 mL)Myocardial contractility, cardiac afterload, cardiac preload; determined by factors affecting venous return
- Preload:
amount of tension (stretch) applied to muscle prior to contraction (depend on force of venous return); also called end diastolic pressure - Afterload
: load against which a muscle exerts force (arterial pressure heart must overcome); if pressure increases, stroke volume decreases, if pressure decreases, stroke volume increases - Contractility:
force with which ventricles contract, depends on stroke of ventricle dilation, which depends on venous return
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Starling’s Law:
- force of ventricular contraction is proportional to muscle fiber length (ventricular diameter)
- [because actin and myosin are better aligned with increased diameter during filling]
- Want to maintain contractility of heart.
- Force of contraction normal increases in proportion to how much ventricle fills.
- If heart muscle is healthy and intact, it will stretch and contract back; repeat readily.
- If heart is “sick” or worn-out/damages, it will stretch and stay; not retractable….
- Eventually will break/fail.
- Becomes extremely ineffective pump.
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Stroke volume is determined by factors that regulate venous return:
Systemic filling pressure (force that returns blood to the heart) [normal is 7 mm Hg, can increase to 17 mm Hg during vasoconstriction]
- Auxiliary muscle pumps
- Resistance
to flow between peripheral vessels and right atrium - Right atrial pressure
(increase impedes venous return)
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Regulation of Arterial Pressure
- Physiologic regulation:
- AP = PR X CO
- (arterial pressure=peripheral resistance X cardiac output)
depends on peripheral resistance due to dilation/constriction of vessels and venous return affecting cardiac output
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Regulation of Arterial Pressure:
Control systems: ANS
- Autonomic Nervous system
- (sec/min)
responds rapidly to changes in blood pressure (baroreceptors in aortic arch and carotid sinus sense arterial pressure and tell medulla vasoconstriction center to constrict or dilate vessels)
steady-state control (sympathetic steady-state tone maintains a moderate level of vasoconstriction so arterial pressure is not compromised)
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Regulation of Arterial Pressure:
Control systems: RAAS
Renin-Angiotensin-Aldosterone System (hours/days)
- Constriction of arterioles and veins (angiotensin II)
- Retention of water by kidney (aldosterone)
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Regulation of Arterial Pressure:
Control systems: RAAS
(long-term control over days/weeks)
decreased renal blood flow and decreased glomerular filtration rate (plus aldosterone) causes increase in water retention -->increase fluid volume-->increase venous pressure--> increase venous return-->increase cardiac output-->increase arterial pressure
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What is Orthostatic Hypertension?
blood pools when you stand up because veins dilate under the pressure caused by gravity; reversed by baroreceptors by constricting veins and arterioles and increasing HR
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Assessing Blood Pressure
- Korotkoff sounds: sounds listened for in blood pressure assessment
- Systolic pressure: first sound, faint tapping that gradually increases
- Diastolic pressure: change or cessation of the loud sounds
Osculatory Gap: if there is a gap between change in sound and cessation of sound, record as a 3-way fraction, ex. 120/80/64
Required equipment: stethoscope and sphygmomanometer(always reset to zero), noninvasive/electronic, Doppler ultrasound, direct electronic (needle into artery)
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Assessing Blood Pressure:
Sources of error
- False Low: hearing deficit, noise in environment, cuff too wide, ear tips wrong, cracked/kinked tubing, released valve too rapidly
- False High: calibration not at zero, taken after exercise, cuff too narrow, released valve too slow, reinflating cuff during auscultation
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Regulation of Body Temperature
- Thermoregulation: hypothalamus, receptors in body tell body if it's hot or cold
- Heat production: metabolism, increased by exercise, own endogenous hormones, diet/food intake
- Heat loss: skin, sweat, elimination
- Mechanisms:
- --Increase in temp: hormones, exercise, thyroid, shivering, piloerection (goose bumps)
- --Decrease temp: sympathetic open/closes arteriovenous shunts, sweat, elimination, methods of [radiation, convection, evaporation, conduction]
- Other influences: circadian rhythm, age and gender, environment, stress
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Temperature:
Equipment/Techniques
- Equipment: electronic/digital (oral, rectal, axillary), Tympanic (ear canal), Glass (oral, not mercury—alcohol or petroleum based now), Disposable (patch or tape changes color), Temporal (across forehead), Automated (several vital signs simultaneously)
- Sites: (most common are sublingual, axillary, tympanic)
- --Tympanic: no drainage or scars
- --Oral: close entire mouth around it
- --Rectal: no infants/small children, rectal surgery, diarrhea, neutropenia
- --Axillary: wait if just washed
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What is the Maximum Temp before Brain Damage occurs?
106*F
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Heart Rate:
Physiology/Variations
- Physiology: autonomic nervous system, cardiac SA node
- Parasympathetic: decreases heart rate through vagus nerve
- Sympathetic: increases heart rate and force
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Tachycardia
increased heart rate (100-180 bpm)
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Bradycardia
decreased heart rate (less than 60 bpm)
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Dysrhythmia
irregular pattern of heart beats
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Pulse Deficit
difference between apical and radial pulse rate, indicates all heartbeats are not reaching peripheral arteries or are too weak to palpate
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Heart Rate:
Equipment/Techniques
Equipment: palpation, stethoscope (diaphragm for high frequency/lung sounds, bell for low frequency/heart sounds), Doppler ultrasound stethoscope, cardiac monitor
- Sites:
- -- Peripheral (using three middle fingers): *radial*, carotid/brachial (cardiac arrest), femoral, popliteal, posterior tibial, dorsalis pedis
- -- Apical: if peripheral is difficult, if giving meds that alter HR and rhythm, space between 5th and 6th ribs, about 8cm/3in to left of median line, just below nipple
- -- Apical-Radial: when radial is irregular, take both simultaneously
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Respiration:
Regulatory Cntr, Cellular, Pulmonary
- Respiratory centers: are medulla and pons
- Cellular Respiration: mitochondria (powerhouse) Krebbs Cycle exchange process
- Pulmonary ventilation: exchange of gases in lungs via alveoli and capillary membrane; inspiration (air in), expiration (air out); voluntary control in cerebral cortex; rate and depth changes with body’s demands, especially in high CO2 levels
Ventilation does not mean profusion; oxygen can be taken in with ventilation
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Respiration:
Factors Affecting
age gender, exercise, acid-base balance, brain lesions (hemorrhage/tumor), increased altitude, respiratory diseases, anemia, anxiety, medications, acute pain
- Profusion: can get air in but can’t get it out into body. Something that stops oxygen from being distributed.
- Ex. COPD, pneumonia (PNA)
Pneumonia: O2 sat (oxygen saturation) decreases. Blockage in alveoli prevents oxygen to transfer into capillary cells.
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Respiration:
Assessment
observing/listening or using a pulse oximeter for effectiveness of respirations
Rate(breaths/min), depth (deep/shallow), rhythm (regular/irregular)
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Developmental Considerations For Respiration
- --Baby’s lungs: fluid filled to air filled
- --Children 2nd hand smokers
- --Can hear crackles in lungs in infants and children; totally normal
- --Elders have shallower breaths, sounds are more distant during oscultation (barrel chest: ribcage changes shape; sounds are further away), diaphragm moves less efficient, tissues tend to thicken with age.
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Oxygenation:
Nursing Diagnoses
- Ineffective airway clearance: cough
- Impaired gas exchange (alveoli): cough and deep breath, give fluids
- Intolerant of activity: pace activity, sit down, give fluids
- Altered nutrition, less than body requirements
- Knowledge deficit
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Eupnea
normal respiration (12-20 per minute)
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Tachypnea:
increase rate (increased metabolic rate with fever, high CO2 and low O2)
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Bradypnea
decreased rate (intracranial pressure, narcotics)
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Apnea
periods of no breathing (death can occur if no breath in 4-6 minutes)
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Dyspnea
difficulty or labored breathing
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Orthopnea
dyspneic people breath better when in sitting or standing position
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Afterload
- arterial pressure that the left ventricle must overcome to eject blood
- determined by peripheral resistance
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Peripheral Resistance
- determined by constriction and dilation of arteriolds
- amount of resistive force blood must overcome to flow through
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Baroreceptor Reflex
- Receptors on aortic arch and carotid sinus
- relay info to vasoconstrictor centro of the medulla
- vasoconstrictor center will send appropriate instructions to compensate
- (constrict/dilate to incr. or decr. HR)
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Postural Hypotension
- reduction in arterial pressure when moving from supin or seated position to standing
- blood pools in veins, auxiliary venous pumps and baroreceptor reflex fix it
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Cardiac Output
- CO = HR X SV
- approx 5 L/min
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Preload
- (end diastolic pressure/volume)
- amount of tension (stretch) applied to muscle prior to contraction
- determined by force of venous return
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Ventricular Contractility
- force with which ventricle contract
- determined by cardiac dilation, which is determined by venous return
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RAAS System
- 1. constriction of arteriolds and veins (ango II)
- 2. retention of water by kidney (aldo)
- control of blood pressure
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Venous Capacitance
- dilation of veins allows for higher capacity
- increased by ANP/BNP
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Natiuretic Peptides
- 1. reduce blood volume
- 2. promote dilation of arteriols/veins
- protect cardiovascular system during volume overload (excessive retntion of sodium and water)
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