Showing posts with label NOTES. Show all posts
Showing posts with label NOTES. Show all posts


Hello!!! Are you ready for the ABG storm, then lets proceed, I am with you in every word, if you have any doubt shoot a question in the comment box, Happy reading.

Normal ABG values are as follows:
  1. pH (acid base balance) = 7.35 to 7.45  
  2. CO2 (carbon dioxide) = 35 to 45 
  3. HcO3 (bicarbonate) = 22 to 26
You also must note the following:
  1. CO2 greater than 45 is acidotic
  2. HcO3 less than 22 is acidotic
  3. Co2 less than 35 is alkalotic
  4. HcO3 greater than 26 is alkalotic
How to interpret ABGs?

All you have to do is memorize four basic questions and then answer them in order:

A. Is the ABG normal? If all of them are, then you have a normal ABG and you can stop here. If any one of the values is out of the normal range, then you must move on to the next question.

B. Is the pH Acidotic or Alkalotic?: To determine this you look only at the pH.
  1. Alkalotic: If the pH is greater than 7.40 the patient is Alkalotic.
  2. Acidotic: If the pH is below 7.40 the patient is acidotic.
C. Is the cause respiratory or metabolic?: To determine this, you look at pH and compare it with HcO3 and CO2. If the pH is acidotic, you look for whichever value (HcO3 or CO2) that is also acidotic. If the pH is alkalotic, you look for whichever value (HcO3 or CO2) is also alkalotic.

In this sense, you match the pH with HcO3 and CO2. If the pH matches with the CO2, you have respiratory. If the pH matches with the HcO3, you have metabolic.

Or, put more simply:
  1. Metabolic Alkalosis: If the pH is alkatotic and the HcO3 alkalotic.
  2. Respiratory Alkalosis: If the pH is alkalotic and the CO2 is alkalotic
  3. Metabolic Acidosis: If the pH is acidotic and the HcO3 acidotic.
  4. Respiratory Acidisis: If the pH is acidotic and the CO2 is acidotic.
A special case here would be if the pH matches both the CO2 and HCO3, you have combined acidosis or combined alkalosis.  For example, if the pH is acidotic, CO2 is acidotic and HCO3 is acidotic, you have combined acidosis.  If the pH is alkalotic, CO2 is alkalotic, and HCO3 is alkalotic, you have combined alkalosis.  

D. Is the cause compensated or uncompensated?
  1. Compensated: pH is anywhere inside the normal ranges (Anything between 7.35 to 7.45)
  2. Uncompensated: pH is anywhere outside the normal ranges (greater than 7.45 or less than 7.35, and the value (CO2 or HCO3) that does not match the pH will still be in the normal range.  
  3. Partially compensated: pH is anywhere outside the normal ranges, and the value that does not match the pH will be outside its normal range, indicating the body is attempting to get the pH back to normal.  For example, if the pH (7.20) and CO2 (50) are acidotic, the HCO3 should be on the alkalotic side (27). 
Put A, B, C, and D together and you have your basic ABG interpretation.  That's it.  It's easy.

So, here are some examples: 

1. Ph 7.40, CO2 37, HcO3 23
What do you have here? All the number are within normal range, so you have a normal ABG.
That was easy enough. You need to go no further in analyzing this ABG.
2. ph 7.23, CO2 50, HcO3 22
What do you have here?
A. Is the ABG normal? You can see right away that the pH and CO2 are out of the normal range, so you must move on to the next question.
B. Is the pH acidotic or alkalotic? Since the pH is less than 7.40 it is acidotic.
C. Is is metabolic or respiratory? Since the pH is acidotic and the CO2 also acidotic, then you have respiratory acidosis.
D. Is it compensated or uncompensated? Well, the pH is outside the normal range of 7.35 to 7.45, and the HCO3 is still in the normal range, the ABG is uncompensated. You don't have to look at any other values. You are done.
The ABG is uncompensated respiratory acidosis
2. pH 7.36, CO2 50, HcO3 29,
A. Is the ABG normal? You can see right away that both CO2 and HcO3 are out of the normal range, so you move on to the next question.
B. Is is acidotic or alkalotic: The pH is less than 7.40, so it is acidotic
C. Is the cause respiratory or metabolic?: The pH is acidotic and the CO2 is also acidotic, so you have respiratory acidosis.
D. Is it compensated or uncompensated? Since the pH is within normal limits, it is compensated.

In this example you have compensated respiratory acidosis.

3. pH 7.50, CO2 42, HcO3 33
A. Is the ABG normal? No. Some of the values are outside the normal ranges.
B. Is it acidotic or alkalotic? The pH is greater than 7.40, so it is alkalotic.
C. Is the cause respiratory or metabolic?: You know the pH is alkalotic, so you look for the matching value. The HcO3 is alkalotic, so it matches the pH. So, what you have is a metabolic problem.
D. Is it compensated or uncompensated? Since the pH is outside the normal range of 7.35 to 7.45, it is uncompensated.
Thus, you have uncompensated metabolic alkalosis.
4. pH 7.50, CO2 18, HcO3 24
A. Is the ABG normal? No, pH and CO2 are both out of the normal range.
B. Is it acidosis or alkalosis? Since the pH is greater than 7.40 it is alkalosis
C. Is is respiratory or metabolic? Since the pH is alkalotic and the CO2 is also alkalotic, you have a respiratory problem
D. Is is compensated or uncompensated: It is uncompensated because the pH is outside the normal range of 7.35 to 7.45.
What you have here is uncompensated respiratory alkalosis.

5.  pH 7.07, CO2 89.3, HcO3 26,

A.  Is the ABG normal?  No, all the numbers are out of the normal range

B.  Is it acidosis or alkalosis?  Since the pH is less than 7.40 it is acidotic

C.  Is it respiratory or metabolic?  Since the pH, CO2, and HCO3 are all acidotic, you have a special case called combined acidosis.

D.  Is is compensated or uncompensated? Since the pH is outside the 7.35 to 7.45 range, and the HCO3 is inside its normal range, the ABG is uncompensated.

What you have here is a case of uncompensated combined acidosis. Now, had the HCO3 in this example been on the alkalotic side of its normal range (say 27) this ABG would have been partially uncompensated.

Once you practice these you will be able to do these automatically in your head in only a few seconds just by looking at the numbers. Now you will want to move on to ABG interpretation made easy part II and, once you have oxygenation mastered, you click here for some more advanced ABG examples.

Adult Oxygen Therapy - SIMPLIFIED !!!!

If a patient is unable to oxygenate appropriately on room air, supplemental oxygen may be indicated. This Course should provide you with the wisdom you need to determine what oxygen device to use (if any) and how much oxygen to give to your patient.

First we need some basic definitions:

Supplemental oxygen: Any device that provides more oxygen than what one would get breathing room air.

Hypoxemia: This is when the oxygen in the blood is low, and is generally measured by a PaO2 of 60 or less, or a SpO2 of 90% or less.

PaO2: This is the level of oxygen in the blood. It should be kept at 60 or better to avoid hypoxemia. It’s obtained by invasive Arterial Blood Gas (ABG) or estimated by SpO2.

SpO2: Also called oxygen saturation, pulse ox or sat. This is a non-invasive measurement of the amount of oxygen inspired that gets to the arteries. A normal SpO2 is about 98%. Be aware that a person’s normal SpO2 decreases with age and with some disease processes. The only way it can get to 100% is with supplemental oxygen.

You can use your SpO2 to predict the PO2 using the 4-5-6, 7-8-9 rule as below:
  • SpO2 70% = PO2 of 40
  • SpO2 80% = PO2 of 50
  • SpO2 90% = PO2 of 60 (This is what you want to maintain for most patients)
Therefore, ideally, for most patients you will want the SpO2 to be 90% or greater, or as specified by hospital protocol, or specific physician order.

Fraction of Inspired Oxygen (FiO2): This is the percent of oxygen a patient is inhaling. Room air FiO2 is 21%. By applying supplemental oxygen, the FiO2 can go as high as 100%.
Indications for Oxygen Therapy:
  • To correct hypoxemia
  • To reduce oxygen demand on the heart
  • Suspected or acute marcardial infarction (MI)
  • Severe trauma
  • Post anesthesia recovery
Low flow oxygen devices: These are oxygen devices where some room air will be entrained, and therefore the exact FiO2 cannot be calculated, however it can be estimated.
How much FiO2 is delivered to the patient is dependent on:
  • Liter flow set at the flowmeter
  • Respiratory rate and pattern of the patient
  • Equipment reservoir (stores oxygen)
The following are low flow oxygen devices:

1. Nasal Cannula: The nasal cannula is the most common oxygen device used and the most convenient for the patient. A nasal cannula at 2lpm is usually a good place to start.
You may at times need to estimate the FiO2. How to estimate FiO2 on a nasal cannula? For every liter per minute, the FiO2 increases by 4% as per the chart below:
  • 1 lpm = 24%
  • 2 lpm = 28%
  • 3 lpm = 32%
  • 4 lpm = 36%
  • 5 lpm = 40%
  • 6 lpm = 44%
The liter flow on a nasal cannula should never exceed 6lpm, as studies show doing so is of no added benefit to the patient. Also note that the prongs of a nasal cannula should face down.

A bubbler can be added to humidify the nose to prevent nasal drying and bleeds. This is automatically set up at flows greater than 4lpm, or as ordered by physician.

3. Non-Rebreather Mask (NRB): This is a mask that ideally will bring in 100% Fio2 so long as the liter flow is 15 and there is a good seal between the mask and the patient's face. And all three one-way valves are on the mask to prevent air entrainment.

For legal purposes, however, one flap is always removed just in case the oxygen gets shut off. And therefore the highest FiO2 you can get from an NRB is 75%. The bag acts as a reservoir for oxygen, and therefore allows device to provide higher FiO2s to the patient.

4. Partial Rebreather Mask (PRB): This is basically an NRB with both one-way valves removed from the mask. The estimated FiO2 is 60-65%. Flow should be set at 6-15 lpm.

High Flow Oxygen Devices: These devices meet the inspiratory flow of the patient, and generate accurate FiO2s so long as there is a good seal between the mask and the patient's face. The flows are such that the patient will not be entraining room air that will lower the FiO2. Respiratory rate and tidal volume of the patient have no effect on FiO2 delivered.

Ideally, the larger the entrainment port on the device the lower the FiO2, and the smaller the entrainment port the higher the FiO2. A major disadvantage is a mask is required, and this may be a bit more uncomfortable than a nasal cannula.

1. Venturi Mask: This mask is ideal for patients who are in respiratory distress with high tidal volumes or high respiratory rate to guarantee a certain amount of oxygen.
If a nasal cannula does not provide adequate oxygenation, Venturi Masks set from 28% to 40% are ideal for COPD patients.

Modern Venturi masks come with one or more color coded caps, and whichever one you use the desired liter flow for that particular cap is written right on the cap.
The Venturi Masks used at MMC are set up as follows:

A. White cap:
  • 35% FiO2 set lpm at 9
  • 40% FiO2 set lpm at 12
  • 50% FiO2 set lpm at 15
B. Green cap:
  • 24% FiO2 set lpm at 3lpm
  • 26% FiO2 set lpm at 3lpm
  • 28% FiO2 set lpm at 6lpm
  • 30% FiO2 set lpm at 6 lpm
The liter flow must be at least set at the recommended liter flow for any particular FiO2 that is dialed in. It's okay if it is set too high, yet if it's too low the patient may retain CO2 and the FiO2 may not be lower than what you dialed in.

2. Aerosol set-up: This device will deliver anywhere from 21 to 100% FiO2 depending on how it is set up. The desired flow to set the flow meter at is written write on the cap
Usually a humidity device is connected to the flowmeter, and wide bore tubing connects this to the patient's mask Wide bore tubing acts as a reservoir to obtain higher FiO2s.

These are ideal for patients with tracheotomies because it allows for inspired air to be oxygenated, humidified and even heated if necessary. They can be hooked up to a simple mask, tracheotomy mask, and even a t-piece.

The flow may exceed the required flow, although if it is less the patient may retain CO2, and the FiO2 be lower than desired. On inhalation a mist should be seen coming from mask or reservoir.

3.  High flow nasal cannula:  An Fio2 of 21% to 100% may be maintained because the flow meets the patient's spontaneous inspiratory demand.  This is made possible due to thicker tubing and humidified oxygen.

Other oxygen devices you might see:

1. BiPAP: This is a discussion for another day. Still, pressure can be given by a non-invasive mask over the patient’s face to improve ventilation, and to supply any FiO2 from 21% to 100%. These also have other means of improving oxygenation.

4. Ventilator: This is also a discussion for another day. Yet for patients whose oxygen demands exceed any of the above devices, intubation and ventilation with a ventilator may be required. These can supply any FiO2 from 21% to 100%, and also have other means of improving oxygenation.

Hazards of oxygen therapy:
  • Oxygen may suppress the respiratory drive for some COPD patients, and should be used with caution.
  • FIO2s greater than 60% for greater than three hours have been linked to increased risk for lung injury and other future consequences.
What device do you use? Where to start?
  • For most patients, you will start low and work your way up if needed
  • We usually start at 2lpm for most patients and adjust accordingly.
  • If you have a patient in respiratory distress, you may want to start at 40%.
  • However, if the patient is in severe respiratory distress, or is the victim of a trauma, you may want to simply start at 100% and decrease as appropriate
  • All patients suspected of chronic heart failure should be placed on 100% FiO2 and adjusted down from there.
  • All patients who are suspected to be CO2 retainers should be started on 2lpm or, if in respiratory distress, on a venturi mask set no higher than 40%.
  • Still, a majority of patients do quite well on 2lpm.
How much oxygen does a patient need?

Ideally, whatever oxygen device is needed to maintain a SpO2 of 90% or greater or as otherwise specified by a specific oxygen protocol or physician order is indicated.

Oxygen supplementation for uncomplicated acute coronary syndrome is no longer routinely indicated and should only be applied only if the oxyhemoglobin saturation is less than or equal to 94 percent.  The old recommendation was to place all patients complaining of chest pain on 4lpm with the belief that it would increase oxygen to the heart and decrease work of breathing.  I'm simply noting this here because some physicians prefer to stick with the old recommendations, and that's fine.

Sedatives, analgesics (like Morphine) and anesthesia may also depress respiratory drive, and these patients are often placed on oxygen. The amount used is usually 2-3 lpm via nasal cannula, however this depends on the patient, physician, or protocol.

How to determine if oxygen therapy is working:

You know oxygen therapy is working when:
  • SpO2 improved to patient normal (or as determined by physician)
  • Respiratory rate improves
  • Patient tidal volume is not erratic
  • Patient notes improved work of breathing
  • Pulse is normal or improved or improving
  • Blood pressure is improved or improving
  • Underlying condition is improving, or whatever occurred to cause the hypoxemia
How long with an e-cylinder last?

So you want to use an e-cylinder to take a patient to x-ray and you want to know if you have enough oxygen in the tank to make it there. You can use the following formula:
e-cylinder time remaining = .30 (PSI) / LPM


Here are the download links for various notes in pulmonary medicine.. If you have any lecture note pdf, word or ppt, please mail me @, I will upload it, help to spread the knowledge, because Human knowledge belongs to the world.

Newer TB drugs and regimens
Critical Illness Neuromuscular Abnormality (CINMA)
High-altitude and its effects on lung
Recruitment manever in ARDS
Pulmonary diseases due to Non-Tuberculous Mycobacteria
Body plethysmography
Helium dilution technique
Heat therapy in interventional pulmonology
Comparison of various modes of weaning with special focus on NAVA
Ventilation and perfusion in health and disease
Mechanisms and management of refractory asthma
NIV in non-COPD respiratory failure: Current status
Evidence based management of Stage III NSCLC
Approach to an agitated patient in the ICU
Recent advances in diagnostic bronchoscopy
Steroids in ARDS: Current perspective
Air pollutants from a pulmonologist’s perspective
Nutrition in critically ill
Care of lung transplant recipient
Role of EBUS in mediastinal staging of lung cancer
Management of refractory ARDS
Management of PAH
Bronchoscopic interventions in COPD
Management of AKI in critically ill patients
Ventilator associated events and prevention of VAP
Pulmonary rehabilitation
Central sleep apnea
Immunotherapy in lung cancer
DVT prophylaxis in hospitalized medical patients
Recent advances in the management of pulmonary vasculitis
Delirium in ICU
Recent advances in ABPA
Setting PEEP in ARDS & role of esophageal pressure monitoring
Predictors of fluid responsiveness in critically ill
ALK and ROS1 targeted therapy in lung cancer
Management of non-CF bronchiectasis
Analgesia, sedation and NM blockers in ICU
Interpretation of PSG
Management of OSA and OHS
Decentralization of PSG
Newer bronchodilators
Newer anti TB drugs and regimens
Current concepts in prevention of nosocomial pneumonia
Gene Xpert in TB
Newer oral anticoagulants for VTE
Closed loop systems in mechanical ventilation
CT screening for lung cancer
Advances in NIV
Current management of IPF
Monoclonal antibodies in pulmonary medicine
Serum biomarkers of sepsis
Smoking cessation
Occupational lung diseases in India
Diaphragmatic dysfunction
Post lung transplantation care
Domiciliary ventilation
Intrapleural agents for pleural infections
Novel influenza viral infections
Smartphones in ICU
Antifungals in medical ICU
Lung Transplantation: Indications, Prioritization and Preparation
ALK gene rearrangements & ALK Inhibitors in NSCLC
Newer drugs for treatment of tuberculosis
Management of pulmonary arterial hypertension
Jul – Dec 2012
Maintenance treatment for advanced NSCLC
Preoperative pulmonary assessment for lung resection surgery
Preoperative pulmonary assessment for non-thoracic surgery
Bronchoalveolar lavage in interstitial lung diseases
ARDS: current concepts
Assessment of small airways disease
Molecular methods in the diagnosis of drug resistant tuberculosis
Recent advances in diagnostic bronchoscopy
Anesthesia and analgesia for FOB & thoracoscopy
DVT Prophylaxis in hospitalized patients � Current Concepts
Special issues in the management of the critically ill obese patient
Assessment of fluid responsiveness in mechanically ventilated patients
Management of sepsis : have we come a full circle??
Aerosol therapy in ICU
Management of Difficult to Treat Asthma
Positive Pressure Ventilation in OSA
Vaccination in Pulmonary Diseases
Ventilator Waveform Analysis
Assessment of Fitness for Air travel in Pulmonary Diseases
Biomarker mediated management of pneumonia
Endobronchial Ultrasound
Erythropoiesis stimulating agents in lung cancer and medical ICU patients
Cardio-pulmonary testing: physiological basis and clinical implications
Classification and management of pulmonary small vessel vaculitides
Treatment of idiopathic pulmonary fibrosis
Critical illness neuromuscular weakness
Interpretation of sleep disordered breathing on a Level I PSG machine
Newer inhaled drugs for asthma and COPD
Diagnostic approach to fever in the ICU
Ultrasound for assessment of respiratory failure and shock in ICU
Human lung stem cells
Antimicrobial therapy in ICU
Role of bronchoscopy in hemoptysis
Hemodynamic monitoring in the ICU
Non surgical management of hemoptysis and air leaks
Nuclear imaging in pulmonary medicine
Radiological screening for lung cancer
Non-pharmacological management of COPD
Recent advances in treatment of drug resistant Tuberculosis
Pulmonary Infiltrates with Eosinophilia
Recent advances: Enteral nutrition in medical ICU
Difficult weaning : Pathophysiology and Management
Non respiratory functions of the respiratory system
Current concepts in Lung Cancer diagnosis and staging
Agitated patient in ICU
Evaluation and management of disorders of the diaphragm
Obesity – pulmonary perspectives
Systemic manifestation of sleep apnea
Radiation and drug induced lung diseases
Nosocomial pneumonia – approach, prevention and management
Pulmonary hypertension: Current perspectives
Role of serum and exhaled biomarkers in pulmonary diseases
Applied biostatistics for the pulmonologist
Treatment of invasive pulmonary fungal infections
Inhalational devices for the outpatient
Recent, current and potential pandemics of respiratory infections
Blood components and blood substitute therapies in ICU
Advances in management of sepsis and septic shock – Part I
Advances in management of sepsis and septic shock – Part II
Advances in non-surgical management of lung cancer
Unconventional ventilatory and non-ventilatory strategies in ARDS
NIPPV in acute respiratory failure – current status and recent advances
Sleep disordered breathing – diagnosis and management
Interventional Bronchoscopy
Lung Volumes & Airway Resistance
Respiratory Mechanics in mechanical ventilation
Lung in extreme environments
Mechanical Ventilation: New Modes
Congenital and Developmental Anomalies of the Lung
Oxygen and CO2 Cascade
Ventilation-perfusion in Health & Disease
Pulmonary Host Defences
Renal Replacemnt Therapy in ICU
Functional Assessment
Filtration and aerosol therapy in ICU
Humidification in ICU
Fever in ICU
Ultrasound in ICU
Extrapulmonary manifestations of COPD
IPF: recent advances in Management
Genetic and targeted therapies for lung cancer
Recruitment maneuvers: Rationale , Protocols and utility
Chemotherapy Related Complications
Asthma: Targeted therapy
Steroid dependant asthma
Hemodynamic monitoring in ICU
Rheumatological emergencies in ICU
Inhaled drug (non-bronchodilator) therapy
Approach to the critically ill poisoned patient
Anti fungal therapies
Scoring Systems in ICU
Occupational asthma
Advances in diagnosis of TB
Silicosis and silico-tuberculosis
Pulmonary hypertension in CTD
Pre-operative Evaluation for Lung Resection
Management of Sarcoidosis
Pre-operative Evaluation for non-thoracic surgery
Recent Advances in Bronchoscopic procedures
Pulmonary and Extra Pulmonary ARDS: Fizz or Fuss ?
Weaning from Mechanical Ventilator
Exhaled Biomarkers
Pulmonary Rehablitation
Brochiolar Disorders
Air Travel and Lungs
Oxygen-Carbon dioxide transport
Control of Breathing
Bronchiolar disorders
ABG: Clinical interpretation
Pulmonary Hypertension
Advances in treatment of ARDS
Obstructive Sleep Apnea
Inoperable Non Small Cell Lung Cancer
Small cell Lung Cancer
Acute Exacerbation of COPD
HIV-TB Coinfection
Uncommonl ILDs
Idiopathic Interstial Pneumonias
Lungs Ageing, Pregnancy & Excercise
Major Airway Obstruction
LVRS & Bullectomy
Cardio-pulmonary exercise testing
Immunotherapy in asthma
Swan-Ganz catheterisation
Staging of lung cancer
Molecular tools in diagnosis of TB
Pulmonary infections in hematological malignancies
MDR TB in extra-pulmonary sites
Current concepts in Rx of TB
Antibiotic therapy
Nutrition in ICU
NSLC current concepts in Rx
Non Invasive Ventilation
Newer Modes of Ventilation
Respiratory Failure
Emerging Therapies in COPD
Pulmonary Vasculitides
Neuromuscular Weakness in ICU
Chest wall Diseases
Emerging Pulmonary Infections
Malignant Mesothelioma
Nuclear Medicine Techniques in Pulmonology
Current and emerging therapies in pulmonary hypertension
Oragnophosphate poisoning
Anaemia in ICU
Surfactant in health and disease
Oxidative stree and anti-oxidants in respiratory diseases
Immunological agents in respiratory medicine
Lung transplantation
Sedation in ICU
Early detection of lung cancer
Cystic Fibrosis in Asians
Tropical Pulmonary Diseases

 SOURCE : The Department of Pulmonary Medicine Postgraduate Institute of Medical Education & Research (PGIMER) Chandigarh. India