Respiratory & Acid Base Balance

hypoxemia

low oxygen levels in the blood

hypoxia

low oxygen levels in the tissue

which comes first hypoxemia or hypoxia?

hypoexemia

Partial Pressure of oxygen in the arteries (PaO2)

pressure that oxygen exerts in arteries controls amount of oxygen that moves onto the hemoglobin

measures in mmHG

PaO2 normal

90-100 mmHg

When PaO2 is low it is

Hypoxemia

ph normal

7.35- 7.45

CO2 normal

35-45

HCO3 normal

22-26

when the level of pressure the oxygen is exerting in the arteries is High

hemoglobin gets more saturated with oxygen

SpO2 measures

oxygen in out tissues (hypoxia)

SaO2 measures

oxygen pressure in our arteries that allows oxygen to get to our tissues

PaO2 80 mmHg

SaO2 sat 90’s

PaO2 60mmHg

SaO2 sat 70’s

when partial pressure of carbon dioxide is greater than 45mm Hg,

Hypercapnic

High CO2 level stimulates the brain’s respiratory center (medulla)

increase in respiratory rate

in state of chronic hypercapnia eventually medulla

becomes insensitive to CO2 levels

erythropoiesis

chronic hypoxia stimulates erythropoietin secretion by the kidney, which stimulates the bone marrow to synthesize RBCs

Why would someone’s body who is in a chronic hypoxic state want more RBCs

more oxygen delivery, want more carriers

stages to Cor pulmonale

chronic → pulmonary arterial vasoconstriction → pulmonary HTN → Cor Pulmonale

pulmonary HTN

condition of high blood pressure within the pulmonary arterial system

increased workload for right ventricle

increased workload for the right ventricle can lead to

right ventricular failure, a condition known as cor pulmonale

Ventilation (V)

movement of air into and out of the lungs during inspiration and expiration

Perfusion (Q)

movement of blood through the entire body

coordination of ventilation and perfusion

• neurochemical control of ventilation

• mechanics of breathing

• gas transport

• control of the pulmonary circulation

neurochemical control of ventilation

respiratory center, central and peripheral chemoreceptors

mechanics of breathing

major and accessory muscles, lung elasticity, airway resistance, alveolar surface tension, work of breathing

gas transport

distribution of ventilation and perfusion, oxygen transport, carbon dioxide transport

control of the pulmonary circulation

distribution of pulmonary blood flow

CO2

acid, respiratory

HCO3

Base, kidney/metabolic

Respiratory= lungs= carbon dioxide is acidic

either CO2 is high (acidic) or CO2 level is low (alkalotic)

response within minutes because ventilation is easier to regulate

Metabolic=kidneys=bicarb is alkalotic

either HCO3 is high (alkalotic) or HCO3 level is low (acodic)

response takes longer since it responds with a change in acidity or alkalonity of the blood at the glomerulus?

ROME

respiratory opposite, metabolic equal

Co2 up, ph down; bicarb up, ph up

Co2 down, ph up; bicarb down, ph down

Respiratory acidosis

increased CO2

• rapid, shallow respiration, decrease BP with vasodilation, dyspnea, headache muscle weakness, hyperkalemia

causes: decrease respiratory stimuli, COPD, pneumonia, atelectasis

Respiratory Alkalosis

decreased CO2

• seizures, deep, rapid breathing, hyperventilation, tachycardia, hypo or normal BP. numbness, lethargy, confusion, light headedness, nausea, vomiting

causes: hyperventilation (anxiety, PE, Fear, mechanical ventilation)

Metabolic acidosis

decreased HCO3

• headache, decreased BP, hyperkalemia, muscle twitching, warm flushed skin, nausea vomiting diarrhea, changes in LOC

causes: severe diarrhea, renal failure, shock

Metabolic alkalosis

increased HCO3

restlessness followed by lethargy, tachycardia, hypoventilation, confusion, nausea, vomiting, diarrhea, tremors, muscle cramps, tingling of fingers & toes

cause: severe vomiting, excessive GI suctioning, Diuretics, excesstive NaHCO3

ph 7.22, PaCO2 58, HCO3 23, SaO2 76

respiratory acidosis with hypoxemia

ph 7.22, PaCO2 35, HCO3 9, SaO2 66

Metabolic acidosis with hypoxemia

ph 7.43, PaCO2 38, HCO3 24, SaO2 76

Normal acid/base balance with hypoxemia

ph 7.49, PaCo2 42, HCO3 32, SaO2 90

Metabolica alkalosis without hypoxemia

ph 7.49, PaCo2 26, HCO3 23, SaO2 90

Respiratory alkalosis without hypoxemia

alterations in pulmonary function

obstructive, infections, lung cancer

Asthma

chronic inflammatory disorder that causes reversible airway constriction due to bronchial hypersensitivity

asthma: pathophysiology

bronchial constriction

inflammation/vasodilation (bronchial edema)

asthma: allergen or trigger

allergens (most common)

gerd

uri

exercise

Asthma diagnostics and testing

spirometry (aka pulmonary function test)

• FEV1 decrease (forced expiratory volume in 1sec)

• FEV1/FVC ratio decrease (forced vital capacity)

peak flow meter (usually for home use; not diagnostic)

allergy testing

chest xray

ABGs

Chronic Obstructive Pulmonary Disease (COPD)

combination of chronic bronchitis and emphysema

caused by combination of genetic and environmental factors:

• alpha-1 antitrypsin deficiency

• smoking is the major cause of COPD

• occupational and environmental exposures to chemicals, dust, and secondhand smoke

emphysema (pink puffers)

loss of alveoli function

• fibrosis in the bronchioles

• over distention of alveoli with trapped air trapping

• loss of elastic recoil of alveoli- loss of surface area for gas exchange

Chronic bronchitis (blue bloaters)

narrowing of the airways

• smooth muscle hypertrophy

• hyper secretion of mucus in large and small airways= chronic productive cough for at least 3 months x2 consecutive years

infections

pneumonia, acute bronchitis, tuberculosis

pneumonia (PNA)

inflammation of the lung tissue in which alveolar air spaces fill with purulent, inflammatory cells, as well as fibrin

infection by bacteria or viruses is the most common cause

ex/ aspiration pneumonia, fungal pneumonia, chemical pneumonia

pneumonia: risk factors

elderly, compromised immunity, lung disease, alcoholism, altered LOC, poverty

CAP

streptococcus pneumonia or called pneumococcal

30% of the adult CAP

pneumovax: PCV15 or PCV20 7 PPSV23

healthcare Acquired Pneumonia (HAP)

methicillin resistant staph aureus (MRSA)

Ventilator Acquired Pneumonia (VAP)

MRSA, Vancomycin resistant enterococcus

secondary pneumonia

influenza, RSV, COVID19, Pertussis (whooping cough)

vaccine yearly

Opportunistic Pneumonia

fungal pneumonias

signs and symptoms of pneumonia

cough, fever, chills, pleuritic chest pain, dyspnea, decreased tolerance, muscle aches, headache, tachypnea, diagnostics:CXR, CBC,ABGs, SpO2, sputum culture

acute bronchitis

acute infection or inflammation of the airways or bronchi

similar symptoms to pneumonia but does not demonstrate pulmonary consolidation and chest infiltrates

Tuberculosis (TB)

usually found in lungs, but spread via bloodstream to lymph nodes, vertebrae, adrenal gland

most common infectious disease in the world with highest mortality rate of all infectious diseases

pathophysiology of TB

airborne, aerobic, as bacilli multiply tissues become inflamed, macrophage and WBC migrate to the infected area, WBCs cannot kill the organisms but wall off the infection, lesion called tubercle, can be inacive/dormat then reactive later

diagnosis of TB

sputum culture for acid-fast bacilli

mantoux tuberulin skin test

interferon gamma release assay (only test exposure)

lung cancer

leading cause of cancer related death in both men and women throughout the world

leading cause is smoking

Non-small cell lung cancer (NSCLC)

makes up about 85% to 90% of all lung cancers

slow growing

develops subtly over a longer period of time

cell types: squamous, adenocarcinoma & large cell carcinoma

small cell lung cancer (SCLC)

rapidly growing

can be neuroendocrine in orgin

tend to metastasize quickly

symptoms of lung cancer

persistent cough, hemoptysis, dyspnea, chest pain, hoarseness, recurrent pneumonia, weight loss, fatigue