Chapter 62: Respiratory Distress Flashcards
This is a feeling of difficult, labored and uncomfortable breathing
Dyspnea
Dyspnea in the recumbinant position
Orthopnea (most often result fo left ventricular failue other cause are diaphragmatic paralysis and COPD)
Dyspnea associated with lying on one side (lateral decubitus position) but not the other side
Trepopnea (side of disease lungs to increase blood supply)
Dyspnea in the upright position
Platypnea
What are the causes of platypnea?
Loss of abdominal wall muscular tone and right to left shunt (patent foramen ovale)
The sensation of dyspnea occurs when imbalance exists among
- Inspiratory drive
- Efferent activity to the respiratory muscles
- Feedback from these afferent
When patient presents with parodoxical abdominal wall movement it means?
Diaphragmatic fatigue
What is the prominent feature of acute heart failure?
Dyspnea
What symptoms patient with dyspnea suggest cardiac in origin than pulmonary?
- S3 gallop
- Pulmonary congestion/intertitial edema
- Cardiomegaly
- Neck vein distention
Causes of dyspnea in the ED can be identified by
- History
- PE
- ECG
- POCUS
- Chest xray
Can use to diagnose dyspnea resulting from COPD
Bedside spirometric analysis
Can assess strength of the diaphragm and inspiratory muscle
Negative inspiratory force (use in neuromuscular disease)
Test can be use to identify ventricular overload
BNP
Normal level of BNP and pro-BNP
BNP <100
pro-BNP <300
BNP value that have no utility in excluding or including heart failure in the dyspneic patient
BNP 100 - 500
Test that can be helpful in evaluation dyspnea in the ED
BNP and D-dimer
In severe dyspnea what is the initial treatment goal?
PaO2 >60
SaO2 =/>90%
What is hypoxia?
Insufficient alveolar oxygen content or insufficient delivery of oxygen to the tissue
Oxygen delivery is a product of?
CaO2 multiply to cardiac output
Tissue hypoxia occurs in state of?
- Low cardiac output
- Low hemoglobin
- Low SaO2
What is hypoxemia?
An abnormally low arterial oxygen tension (PaO2 <60mmHg)
What is the most common cause of hypoxemia?
Alveolar hypoxia
What is relative hypoxemia?
Term used when the arterial oxygen tension is lower than expected for a given level of inhaled oxygen
How to calculate Alveolar oxygen partial pressure?
- Inhaled oxygen concentration (21%)
- Atmospheric pressure (760mmHg)
- Displacement by water vapor (47mmHg)
- CO2
What is normal P(A-a)o2?
<10mmHg
Predicted formula for P(A-a)o2
P(A-a)o2 = 2.5 + 0.21 (age in years) (± 11)
Hypoventilation mechanism
increased PaCO2 and normal A-a O2 gradient
Why is there always a some degree of right to left shunting?
Direct left atria return from coronary and bronchial veins
Right to left shunt mechanism
Increase in the A-a O2 gradient
What is the hallmark of significant right to left shunting?
Failure of arterial oxygen levels to increase in response to supplemental oxygen
All the mechanism that increase A-a O2 gradient improves with oxygenation except?
Right to left shunting
What are the mechanism of hypoxemia?
- Hypoxia
- Right to left shunt
- V/Q mismatch
- Diffusion impairment
- Low inspired oxygen (high altitude)
However, the acute compensatory mechanisms are always activated when Pao2 reaches _____, and compensatory mechanisms fail when Pao2 falls below ____.
However, the acute compensatory mechanisms are always activated when Pao2 reaches 60 mm Hg (8 kPa), and compensatory mechanisms fail when Pao2 falls below 20 mm Hg (2.67 kPa).
Define hypercapnia
Paco2 >45mmHg
What are the causes of alveolar hypoventilation?
- Decrease in respiration
- Decrease in tidal volume
- Increase in dead space
How COPD can produce alveolar hypoventilation?
Increase in dead space
Acute elevation of PaCO2 at what level can cause cardiovascular collapse?
PaO2 >100mmHg
Acute CO2 - bicarbonate equilibrium
10mmHg:1mEq/L
Chronic CO2 - bicarbonate equilibrium
10mmHg:3.5mEq/L
How can hypercapnia treated?
Increase minute ventilation and tidal volume
This drug is use as respiratory stimulant
Doxapram
What is acute, subacute and chronic cough?
Acute <3 weeks
Subacute 3-8 weeks
Chronic >8 weeks
Acute cough is usually cause by what?
Self -limited upper respiratory or bronchial infections
What is the hallmark of acute bronchitis?
Productive cough
Pertusis cough is acute ranging from?
1 - 6 weeks
Most common cause of chronic cough
- Smoking (morning)
- Upper airway cough syndrome (postnasal discharge)
- Asthma (night)
- GERD
- ACE blocker
What is the mechanism of cough in ACE inhibitor?
Accumulation of bradykinin and substance P taht stimulates pulmonary cough receptors
Part of most proprietary cough preparations, soothe the pharynx and modestly alter the cough reflex
Demulcents
Drug that reduces coughin in patients with acute bronchitis?
Naproxen
For patient with intractable coughing paroxysmal in the ED, we can give what?
Lidocaine 4ml (40 or 80mg) neb - suppres gag reflex due to posterior pharyngeal anesthesia
What is hiccups?
Involuntary spastic contraction of the inspiratory muscle
What are the causes of hiccups?
Stimulation, inflammation and injury to the nerves (phrenic and vagus)
What are the classifications of hiccups?
Benign <48 hours
Persistent <48 hours
Intractable >1 month
What are the example of benign hiccups?
- Gastric distention
- Alcohol ingestion
- Smoking
- Changes in temperature
Drug that stimulates hiccups
Chemotherapy and Dexamethasone
If the hiccups is called psychogenic in cause what is the characteristic?
Resolution during sleep
If patient with persistent hiccups what can you do at ED?
- Look at external auditory canal
- CXR
- Fluoroscopy - diaphragmatic movement
Method that can be use to eliminate hiccups
- Swallowing a teaspoon of dry granulated sugar
- Sip ice water
- Drink water quickly
What drug can you give with intractable hiccups?
Chlorpromazine (FDA approved) 25-50mg IV every 2-5 hours and Metoclopromide
Give some example of persistent and intractable hiccups
- CNS lesions
- Uremia, hyperglycemia
If intractable hiccups does not resolve to Chlorpromazine you can give what?
- Nifedipine
- Valproic avid
- Baclofen
- Gabapentin
Reason for patient with central cyanosis?
Inadequate pulmonary oxygenation and abnormal hemoglobin
Cyanosis is usually visible when deoxygenated hemoglobin exceeds _____
Cyanosis is usually visible when deoxygenated hemoglobin exceeds 5 grams/dL (50 grams/L)
This is called a bluish discoloration of skin due to drugs
Pseudocyanosis (normal lips and mucous membrane)
Sample drugs that can produce pseudocyanosi?
- Chlorpromazine
- Minocycline
- Amiodarone
- Nicorandil
- Gold
- Silver
What will pulse oximetry show in patients with methemoglobinemia and carboxyhemoglobinemia?
- Methemoglobinemia (overestimate the true oxygen saturation)
- Carboxyhemoglobinemia (read as oxyhemoglobin so overestimate)
Administer oxygen to all patients with central cyanosis; failure to improve suggests what?
- Shock
- Abnormal hemoglobin
- Pseudocyanosis
In developed country, what is the most common cause of pleural effusion?
- Heart failure
- Pneumonia
- Cancer
How many ml of fluids per day is reabsorbed by visceral microcirculation?
8 L/d
Pleural effusion in chest xray upright seen is about how many ml?
150-200ml
How can you say that pleural effusion is significant?
A significant pleural effusion is large enough to produce a pleural fluid strip >10 mm wide on lateral decubitus radiographic views or by US
How can diuretics obscure the distintion between exudates and transudates. If known transudative pleural effusions?
The resorption of water is faster than the protein. So protein concentration is increase in the range consistent with exudative etiology
Thoracentesis is indicated with pleural effusion when?
If with dyspnea at rest (1-1.5L)
What are the components of light criteria?
- Protein
- LDH
What is the normal pleural fluid ph?
Around 7.64
Increase pleural fluid amylase indicates?
- Pancreatitis
- Esophageal rupture