abg interpretation examples

Muna Kalati

Reduced compliance of the lung tissue/chest wall (e.g. They should always be interpreted as part of a wider assessment of a patient’s respiratory function and in line with your organisation’s policies. This would indicate that the patient normally retains CO2 and has a chronically raised HCO3. If PaO2 is <10 kPa on air, a patient is considered hypoxaemic. Raised JVP, ankle swelling, fine basal creps: more likely oedema. The idea of ‘compensation’ is that the body can try and adjust other buffers to keep the pH within the normal range. Metabolic acidosis can occur as a result of either: A metabolic acidosis would have the following characteristics on an ABG: The anion gap (AG) is a derived variable primarily used for the evaluation of metabolic acidosis to determine the presence of unmeasured anions. Your email address will not be published. [/toggle title="What' s the differential diagnosis of this ABG picture?" Lifestyle advice and smoking cessation of necessary. DKA, lactic acidosis (produced by poorly perfused tissues), From the GI tract (diarrhoea or high-output stoma), E.g. A respiratory alkalosis would have the following characteristics on an ABG: Causes of respiratory alkalosis include: ³. Try to look at as many real life examples as you can, and don’t be afraid to get it wrong! This method is simple, easy and can be used for the majority of ABGs. A collection of free medical student quizzes to put your medical and surgical knowledge to the test! Respiratory alkalosis with no metabolic compensation. It only addresses acid-base balance and considers just 3 values. Metabolic compensation for a respiratory disorder, however, takes at least a few days to occur as it requires the kidneys to either reduce HCO3– production (to decrease pH) or increase HCO3– production (to increase pH). A 17-year-old patient presents to A&E complaining of a tight feeling in their chest, shortness of breath and some tingling in their fingers and around their mouth. Treatment is directed towards correcting each primary acid-base disturbance. To work out if the metabolic acidosis is due to increased acid production or ingestion vs decreased acid excretion or loss of HCO3– you can calculate the anion gap. Either way, this is a raised anion gap metabolic acidosis. EXAMPLE 6 31 year old AAM took too many pills for suicide attempt Na 139, K 5.2, Cl 110, CO2 16, BUN 47, Cr 6.8, Glu nl What is disturbance? ABG Examples (ABG exam questions for medical students OSCEs and MRCP PACES) Below are some brief clinical scenarios with ABG results. A comprehensive collection of OSCE guides to common clinical procedures, including step-by-step images of key steps, video demonstrations and PDF mark schemes. If it outside range, then it is uncompensated or partially compensated. A collection of anatomy notes covering the key anatomy concepts that medical students need to learn. The changes in pH are caused by an imbalance in the CO2 (respiratory) or HCO3– (metabolic). It explains each component in turn followed by clinical examples to work through. Note this is an acidosis, not an acidaemia (pH normal, but only due to compensatory mechanisms: the high bicarbonate). What is your interpretation? 1. A 67 year-old man with a history of peptic ulcer disease presents with persistent vomiting. There is an initial respiratory alkalosis due to central respiratory centre stimulation causing  increased respiratory drive. Winner of the Standing Ovation Award for “Best PowerPoint Templates” from Presentations Magazine. ABG Quick Interpretation Parameter Acidosis Normal Alkalosis Reflects pH < 7.35 7.35-7.45 > 7.45 Acid/Base Status of Body pCO2 > 45 35-45 < 35 Respiratory Component HCO3 < 22 22-26 > 26 Metabolic Component Facts: Body will not overcompensate when it … They have no significant past medical history and are not on any regular medication. Iatrogenic (e.g. See whether pH is within normal range or not. Interactive medical education From Adam Weinberger Start learning. Reservoir masks deliver oxygen at concentrations between 60% and 90% when used at a flow rate of 10–15 l/min.³ The concentration is not accurate and will depend on the flow of oxygen as well as the patient’s breathing pattern. These disorders are termed complex acid-base or mixed disorders. As a result, PaCO2 is reduced and pH increases causing alkalosis. Met acidosis or chronic resp alkosis ABG 7.30/30/80/15 = appropriate resp compensation No other disturbance present What is Gap? Try to interpret each ABG and formulate a differential diagnosis before looking at the answer. Plasma salicylate concentration (initial and repeats), Paracetamol levels (always check in any case of poisoning by anything), Renal failure (rare) sometimes other electrolyte imbalances, If dropping sats or any suspicion of ARDS (non-cardiogenic pulmonary oedema), Gastric lavage within 1h of ingestion (although no evidence for mortality reduction), In mild/moderate cases (plasma concentration 500-700mg/l), Give 225ml of 8.4% bicarbonate solution over 1hr, Ensure urine pH over 7.5 (use indicator paper), Bicarbonate will increase any pre-existing hypokalaemia – so don’t let it happen, Additional boluses of bicarbonate to maintain alkalinisation, N.B. Assess . HCO3- is 35. thanks for the questions. This is a picture of a mixed respiratory and metabolic acidosis. Hemodynamics. Some analysers won’t include potassium in their calculations therefore for them >15 constitutes a raised anion gap. You persuade her to let you do an ABG: A few hours later she says she feels increasingly unwell and is complaining of ringing in her ears. The rise in PaCO2 rapidly triggers an increase in a patient’s overall alveolar ventilation, which corrects the PaCO2 but not the PaO2 due to the different shape of the CO2 and O2 dissociation curves. Rationale pH 7.39. Reduced strength of the respiratory muscles (e.g. Thankyou, this was great practice for my exam. If abnormal, does this abnormality fit with the current pH (e.g. excessive mechanical ventilation), Iatrogenic (e.g. A pH of 7.49 is higher than normal and therefore the patient is alkalotic.Â. increased HCO3-/base excess in a patient with COPD and CO2 retention) you can assume that the respiratory derangement has been ongoing for at least a few days, if not more. This is a compensated respiratory acidosis. Investigations such as arterial blood gases […] This works the other way around as well; if the cause of a pH imbalance is metabolic, the respiratory system can try and compensate by either retaining or blowing off CO2 to counterbalance the metabolic problem (via increasing or decreasing alveolar ventilation). Step 2. A comprehensive collection of clinical examination OSCE guides that include step-by-step images of key steps, video demonstrations and PDF mark schemes. The normal range for HCO3 is from 22 to 26. If the cause of the pH imbalance is from the respiratory system, the body can adjust the HCO3– to counterbalance the pH abnormality bringing it closer to the normal range. An ABG can also give pH readings of the blood sample taken from the artery. covers the basic for an undergraduate. Looking at the level of CO2 quickly helps rule in or out the respiratory system as the cause for the derangement in pH. What interventions would be appropriate for Ms. The CO2 is low, which would be in keeping with an alkalosis, so we now know the respiratory system is definitely contributing to the alkalosis, if not the entire cause of it. For these ABG values, pH is NORMAL but slightly acidic and lines up with PACO2 which is METABOLIC. Click here for a page detailing this, and click here for. So we now know the respiratory system is NOT contributing to the acidosis and this is, therefore, a metabolic acidosis. The end result is hypoxaemia (PaO2 < 8 kPa) with normocapnia (PaCO2 < 6.0 kPa).¹. This site uses Akismet to reduce spam. Interpretation of Arterial Blood Gases is a sample topic from the Pocket ICU Management.. To view other topics, please sign in or purchase a subscription.. Anesthesia Central is an all-in-one web and mobile solution for treating patients before, during, and after surgery. 2) Where PAO. pH: 7.26 center_focus_strong. Each clinical case scenario allows you to work through history taking, investigations, diagnosis and management. Venturi masks are available in the following concentrations: 24%, 28%, 35%, 40% and 60%. Practice examples. ABG Value. He says that she took lots of tablets. This is type 1 respiratory failure. Hypoventilation can occur for a number of reasons including: Seemingly small abnormalities in pH have very significant and wide-spanning effects on the physiology of the human body. Thanks. Check . Junior doctor with a special interest in medical education. This is an extremely worrying sign as it shows that the patient is tiring. This is the classic picture of aspirin overdose. Subscribe to Resus. The severity of the metabolic acidosis is masked by the respiratory system’s attempt at compensating via reduced CO2 levels. Anion gap formula: Anion gap = Na+ – (Cl- + HCO3-). A patient is brought back to the floor from the operating room on a patient controlled analgesia (PCA) pump with hydromorphone. Arterial Blood Gas. An ABG is performed on room air reveals the following: A pH of 7.33 is lower than normal and therefore the patient is acidotic.Â. Below are the terms used to label abnormal ABG results: Respiratory Acidosis (uncompensated, partially compensated, or fully compensated) Respiratory Alkalosis (uncompensated, partially compensated, or fully compensated) Metabolic Acidosis (uncompensated, partially compensated, or fully compensated) The CO2 is low, which rules out the respiratory system as the cause of the acidosis (as we would expect it to be raised if this was the case).Â. Type 1 respiratory failure involves hypoxaemia (PaO2 <8 kPa) with normocapnia (PaCO2 <6.0 kPa). With the above history this is likely to represent an acute on chronic respiratory acidosis. Guillain-Barré, motor neurone disease). gastric outlet obstruction (the classic example is pyloric stenosis in a baby). a mixed acid/base disorder). The drop in pH represents the normal mechanisms of compensation being over whelmed. They mostly come from collected results of volunteers or study subjects who appear to have uncompromised lungs and gas exchange. There is no evidence of metabolic compensation of the respiratory alkalosis (which would involve a lowered HCO3-) suggesting that this derangement is relatively acute (as metabolic compensation takes a few days to develop). Interactively analyze ABGs. More information can be found on this page: The British Thoracic Society have produced guidelines which give a, Hypermetabolic states (e.g. You may also be interested in our guide to. She has her final university exams next week. These work as buffers to keep the pH within a set range and when there is an abnormality in either of these the pH will be outside of the normal range. PATIENT 1 A 68-year-old woman is admitted with abdominal pain, which is later found to be due to a pelvic abscess causing sepsis. The use of Venous Blood Gasses is becoming more widespread, especially in the emergency department. An ABG is performed and reveals the following: A PaO2 of 14 on room air is at the upper limit of normal, so the patient is not hypoxic. Oxygen administration in this group is a complicated issue. o Hypoxic? Based on the given ABG values, PaCO2 is above 45, so it is considered ACIDOSIS. PaO2 should be >10 kPa when oxygenating on room air in a healthy patient. Below are a few examples to demonstrate how important context is when interpreting an ABG: Your first question when looking at the ABG should be “Is this patient hypoxic?” as hypoxia is the most immediate threat to life. Broadly speaking the causes can be either metabolic or respiratory. If Normal, the blood gas is compensated or not. The Arterial Blood Gas (ABG) Analyzer interprets ABG findings and values. HCO3– is low, which is in keeping with a metabolic acidosis. ST-Elevated MI. Approach To Interpretation of ABG. Click here to interpret some ABG values using these steps. It’s important to note that ‘over-compensation’ should never occur and, therefore, if you see something that resembles this you should consider other pathologies driving the change (e.g. So for example, you may know your patient’s pH is abnormal but you don’t yet know the underlying cause. *This table is able to classify most clinical blood gas values but not all. They are suitable for all patients needing a known concentration of oxygen, but 24% and 28% Venturi masks are particularly suited to those at risk of carbon dioxide retention (e.g. Below are a few examples to demonstrate how important context is when interpreting an ABG: A ‘normal’ PaO 2 in a patient on high flow oxygen : this is abnormal as you would expect the patient to have a PaO 2 well above the normal range with this level of oxygen therapy. When a patient is ‘blowing off’ CO2 there is less of it in the system and, as a result, the patient’s blood will become less acidotic and more alkalotic. Arterial Blood Gas (ABG) interpretation for medical students, OSCEs and MRCP PACES This section presents how to interpret arterial blood gases. This is an unprecedented time. Piecing this information together with the HCO3– we can complete the picture: You may note that in each of these tables HCO3– and CO2 are both included, as it is important to look at each in the context of the other. Reference range usually 7–16 mEq/L (but varies between hospitals, some using 3-11). Â. We now know that the patient has a metabolic acidosis and therefore we can look back at the CO2 to see if the respiratory system is attempting to compensate for the metabolic derangement. ABG Ninja! Learn how your comment data is processed. Check out our brand new medical MCQ quiz platform at https://geekyquiz.com. A 21 year-old woman presents feeling acutely lightheaded and short of breath. patients with chronic obstructive pulmonary disease).³. ABG = 7.50/34/90/21/95 → pH is high, HCO3 is low & CO2 is low (but it doesn’t matter that HCO3 is low because in alkalosis, HCO3 is supposed to be high) Anion Gap Acidosis O … Explanation & Examples on Solving ABGs Problems. Arterial Blood Gas Interpretation Information in this slide presentation is adapted from All You Really Need to Know to Interpret Arterial Blood Gases (2 nd … Slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. Examples of these situations could be hypoventilation, asphyxia, central nervous system depression, chronic obstructive pulmonary disease, infection, and drug-induced respiratory depression (Table 9). Guideline for emergency oxygen use in adult patients. At this point, prior to assessing the CO2, you already know the pH and the PaO2. A repeat gas shows: A normally fit and well 11 year-old boy presents with diarrhoea and vomiting. To make things simple, I will only refer to the three basic ABG values in this post. It’s worth mentioning that it is possible to have a mixed acidosis or alkalosis (e.g. b. 36 Terms The next step is to look at the HCO3– and see if it is also contributing to the alkalosis. A 16-year-old female presents to hospital with drowsiness and dehydration. An important point to recognise here is that although the derangement in pH seems relatively minor this should not lead to the assumption that the metabolic acidosis is also minor. Arterial blood gas (ABG) interpretation is something that can be difficult to grasp initially (we’ve been there). Berth? Researchers plotted the results of the various parameters, found the collective center of the bell-shaped curve of data, and declared the results shown in Table 1. The underlying cause of respiratory alkalosis, in this case, is a panic attack, with hyperventilation in addition to peripheral and peri-oral tingling being classical presenting features. The accompanying alkalosis is a response, due to the patient blowing off CO2 due to her likely high respiratory rate. Mr. Frank has an uncompensated respiratory acidosis with hypoxemia as a result of his pneumonia. The ABG values one would see with respiratory acidosis would be: pH < 7.35; PaCO 2 > 45 mmHg; and HCO 3 > 26 mEq/L if compensating. ABG interpretation Analyze the following ABG . Rather it reflects a compensation for a chronic respiratory acidosis secondary to chronic pulmonary disease. The ABG interpretation is the analysis of results found through arterial blood gas. These steps will make more sense if we apply them to actual ABG values. Settings. Once you’ve worked through them, head over to our ABG quiz for some more scenarios to put your newfound ABG interpretation skills to the test! Below is a quick reference guide, providing some approximate values for the various oxygen delivery devices and flow rates you’ll come across in practice.2, As with all oxygen delivery devices, there is a significant amount of variability depending on the patient’s breathing rate, depth and how well the oxygen delivery device is fitted. Where do these normal values come from? Below are some guides to various oxygen flow rates and the approximate percentage of oxygen delivered:4, The oxygen delivery of simple face masks is highly variable depending upon oxygen flow rate, the quality of the mask fit, the patient’s respiratory rate and their tidal volume. Arterial blood gas analysis is used to measure the pH and the partial pressures of oxygen and carbon dioxide in arterial blood. She denies this. active="false"]. Alveolar-arterial gradient = partial pressure of oxygen in airways (PAO ) – partial pressure of oxygen in artery (PaO. Potassium is commonly left out of the equation as potassium concentrations, being very low, usually have little effect on the gap. You are called to see a 54 year old lady on the ward. Show Base Excess . Based on the history, anxiety hyperventilation is the most likely cause here. This is one of the cases where having an old ABG from a previous admission can be useful. Given the history of diabetes and ankle swelling, renal failure is a unifying diagnosis with pulmonary oedema contributing to a respiratory acidosis whilst the failure to clear acids causes a metabolic acidosis. The real value of an ABG comes from its ability to provide a near-immediate reflection of the physiology of your patient, allowing you to recognise and treat pathology more rapidly. 2. A collection of interactive medical and surgical clinical case scenarios to put your diagnostic and management skills to the test. laryngeal mask airway [LMA], i-Gel), click here to learn the best way to interpret ABGs, Lower limb venous system vascular examination, Epigastric pain case study with questions and answers, Guedel Airway Insertion – Initial Assessment of a Trauma Patient. addition of excess alkali such as milk-alkali syndrome), Liver cirrhosis in addition to diuretic use, The British Thoracic Society. We need to consider the driving force behind the change in pH. Step 1 Normal pH PaCO2 40. CO2 binds with H2O and forms carbonic acid (H2CO3) which will decrease pH. Using the 7 Step System for gas interpretation( we only need the first 2 steps here): Step 1: ... I’m just wondering when it comes to the written exam if they’ll be accepting of the range of approaches / worked examples? These masks should not be used with flow rates less than 5L/min.³. ↑ CO2). opiates). Normal . Wheeze will predominate in asthma. respiratory and metabolic acidosis/respiratory and metabolic alkalosis). The nurse says that although the patient’s respiratory rate has come down slightly she is looking more unwell. ECG Rhythms. #abg normal values#respiratory acidosis#respiratory alkalosis#metabolic acidosis#metabolic alkalosis#compensated and partially compensated 11: Transcultural Nursing Care in the Community. They'll give your presentations a professional, memorable appearance - the kind of sophisticated look that today's audiences expect. A 62 year-old woman with a history of diabetes and a long smoking history presents to the emergency department with worsening shortness of breath. An Arterial Blood Gas, or ABG for short, is a test that measures the blood levels of oxygen (PaO2), carbon dioxide (PaCO2), and acid-base balance (pH) in the body.It’s a test that is used to assess how well oxygen is being distributed throughout the body and how well carbon dioxide is being removed. For example ABG's with an alkalemic pH may exhibit respiratory acidosis and metabolic alkalosis. By the time your test comes up you should be an ABG interpretation expert. A collection of surgery revision notes covering key surgical topics. A 32 year-old man presents to the emergency department having been found collapsed by his girlfriend. A 75 year old gentleman living in the community is being assessed for home oxygen. ↑ CO2 ↓ HCO3– in mixed respiratory and metabolic acidosis). Try to interpret each ABG and formulate a differential diagnosis before looking at the answer. It could be caused by the respiratory system (abnormal level of CO2) or it could be metabolically driven (abnormal level of HCO3-). Metabolic acidosis with respiratory compensation. Type 2 respiratory failure involves hypoxaemia (PaO2 <8 kPa) with hypercapnia (PaCO2 >6.0 kPa). Drugs acting on the respiratory centre reducing overall ventilation (e.g. Available from: [, The University of Louisville. Rule-based (rather than image-based) ECG practice. if the CO, Respiratory acidosis/alkalosis (changes in CO, Metabolic acidosis/alkalosis (changes in HCO, Guillain-Barre: paralysis leads to an inability to adequately ventilate, Chronic obstructive pulmonary disease (COPD), Iatrogenic (incorrect mechanical ventilation settings). The Arterial Blood Gas (ABG) Analyzer interprets ABG findings and values. An ABG can provide information about the levels PaO2 and PaCO2 which indicate partial oxygen and carbon dioxide pressure. However, it is very important to have considered the other options, in particular and to have ruled out a primary respiratory pathology or infection. mmHg. PaO2 greater than 7.3 and less than 8.0 kPa when stable AND with any of: is the difference between primary measured cations (sodium and potassium) and the primary measured, Myasthenia Gravis (MG) – Neurological Examination, Questions about DVT (Deep Vein Thrombosis), Endotracheal tube (ETT) insertion (intubation), Supraglottic airway (e.g. Cancel OK . ↓HCO, If the abnormality doesn’t make sense as the cause for the deranged pH, it suggests the cause is more likely respiratory, Start typing to see results or hit ESC to close, DNACPR Discussion and Documentation – OSCE Guide, Cervical Spine X-ray Interpretation – OSCE Guide, Musculoskeletal (MSK) X-ray Interpretation – OSCE Guide, medical MCQ quiz platform at https://geekyquiz.com, Benign Paroxysmal Positional Vertigo (BPPV), Respiratory acidosis with metabolic compensation, Respiratory alkalosis with metabolic compensation, Metabolic acidosis with respiratory compensation, Metabolic alkalosis with respiratory compensation, Reduced ventilation and normal perfusion (e.g. On auscultation of the chest there are widespread crackles and you notice moderate ankle oedema. Normal PaCO2 Interpretation Normal ABG (acid base is balanced; there are no pH changes, so if the respiratory acid is normal, the metabolic base cannot be causing changes either.) Acidosis increases salicylate transfer across the blood brain barrier, In severe cases (plasma concentrations >700mg/l), Priorities for management include fluid resuscitation, insulin administration and careful management of potassium levels. The most important points when assessing a patient are the history, examination and basic observations. Case A. pulmonary oedema, bronchoconstriction), Reduced perfusion with normal ventilation (e.g. He is complaining of non-specific abdominal pain. Acid Base Balance (pH) Therefore, paying close attention to pH abnormalities is essential. It occurs as a result of alveolar hypoventilation, which prevents the patient from being able to adequately oxygenate and eliminate CO2 from their blood. A collection of communication skills guides, for common OSCE scenarios, including history taking and information giving. No Yes . infection or fever). Pyrexia points more towards pneumonia (but PE can give a mild pyrexia). CO. 3 ↔ HCO-+ H + STEP 1 – Oxygenation . If the patient is receiving oxygen therapy their PaO2 should be approximately 10kPa less than the % inspired concentration FiO2 (so a patient on 40% oxygen would be expected to have a PaO2 of approximately 30kPa). An increased anion gap indicates increased acid production or ingestion: A decreased anion gap indicates decreased acid excretion or loss of HCO3–: Metabolic alkalosis occurs as a result of decreased hydrogen ion concentration, leading to increased bicarbonate, or alternatively a direct result of increased bicarbonate concentrations. This ABG is an example of a partially compensated respiratory acidosis. A collection of data interpretation guides to help you learn how to interpret various laboratory and radiology investigations. An ABG is performed on the patient whilst they’re breathing room air and the results are shown below: PaO 2: 14 kPa (11 – 13 kPa) || 105 mmHg (82.5 – 97.5 mmHg) pH: 7.49 (7.35 – 7.45) PaCO 2: 3.2 kPa (4.7 – 6.0 kPa) || 24 mmHg (35.2 – 45 mmHg) HCO 3 –: 22 (22 – 26 mEq/L) BE: +2 (-2 to +2) What does the ABG show? PaO2: 9.87kPa. A FOUR STEP METHOD FOR INTERPRETATION OF ABGS. Differential diagnosis of a metabolic alkalosis or alkalaemia: A seventeen year-old girl presents to the emergency department after an argument with her boyfriend. More ABG Examples. You can see some causes of mixed acidosis and alkalosis below. The traditional mnemonic for the causes of a metabolic acidosis with raised anion gap is ‘MUDPILES’: Copyright 2013-2019 Oxford Medical Education Ltd. Note that the HCO3 is raised in this patient despite the abnormal pH. A comprehensive collection of medical revision notes that cover a broad range of clinical topics. Head over to our ABG quiz for some more scenarios to put your newfound ABG interpretation skills to the test. Which step? So far we have discussed how to determine what the acid-base disturbance is, once we have this established we need to consider the underlying pathology that is driving this disturbance. The fraction of inspired oxygen. Increased resistance as a result of airway obstruction (e.g. As a result of the VQ mismatch, PaO2 falls and PaCO2 rises. The differential diagnosis in this case is: All of these conditions can may you tachypnoeic and tachycardic. Of course then you'll have to practice, practice, practice. It is the dedication of healthcare workers that will lead us through this crisis. CO 2 Units . Available from: [. The next step is to look at the HCO3– to confirm this. If you'd like to support us and get something great in return, check out our PDF OSCE Checklist Booklet containing over 100 OSCE checklists in PDF format. Her initial ABG on 15 litres of oxygen shows: After initial treatment the nurse in resus calls you to review the patient. Arterial Blood Gas Analysis: Example Set 1. They have no previous past medical history and are on no regular medication. 100% oxygen makes subsets of COPD patients retain CO2, decreasing respiratory drive and worsening hypoxia and hypercapnia. Primary problem . It occurs as a result of ventilation/perfusion (V/Q) mismatch; the volume of air flowing in and out of the lungs is not matched with the flow of blood to the lung tissue. Her ABG is as follows: See relevant pages in the respiratory section for further information. If PaO2 is <8 kPa on air, a patient is considered severely hypoxaemic and in respiratory failure. Medical Quizzes . As a result, if you see evidence of metabolic compensation for a respiratory disorder (e.g. Pain: causing an increased respiratory rate. If HCO3 is above 26, it is alkalosis. Type 2 respiratory failure involves hypoxaemia (PaO2 is <8 kPa) with hypercapnia (PaCO2 >6.0 kPa). To interpret ABGs, we first need to know the normal values for the various analytes. A venous blood gas shows: A 22 year-old lady with a known history of asthma presents to the emergency department with difficulty in breathing. Thorax 2008; 63(1). Thank you for everything you do. However, another way is to think about the mechanism of acidosis: [/toggle title="What is the differential diagnosis for a metabolic acidosis with normal or decreased anion gap?" Note that despite the low pH the pCO2 is also high. Note: ABGs should be thought of as a snapshot of how the body is interacting with its environment at a particular time. Answers to the ABG Practice Examples: 1. If abnormal, does this abnormality fit with the current pH (e.g. The next step is to figure out whether the respiratory system is contributing the acidosis (i.e. Whic… Identify various myocardial infarct 12-lead patterns. Our quiz platform also has over 3000 free MCQs across a broad range of topics. The underlying cause of the metabolic acidosis, in this case, is diabetic ketoacidosis. oxygenation. ABG shows: Perfect revision for MRCP PACES, OSCES and medical student finals, Cardiac arrestClinical casesInterpreting investigationsOSCEsPACESPLABQuestionsShortness of breath. Usefulness. o Significant alveolar-arterial gradient? center_focus_strong Metabolic Respiratory Combined. That was an excellent practice for learning ABG interpretation In these circumstances, the CO2 and HCO3– will be moving in opposite directions (e.g. These masks are most suitable for trauma and emergency use where carbon dioxide retention is unlikely. Simple face masks can deliver a maximum FiO2 of approximately 40%-60% at a flow rate of 15L/min. We now know the pH and whether the underlying problem is metabolic or respiratory in nature from the CO2 level. You are called to see a 54 year old lady on the ward. really useful. In the later stages a metabolic acidosis develops along side the respiratory alkalosis as a result of direct effect of the metabolite salicylic acid and more complex disruption of normal cellular metabolism. or. active="false"]. The PO2 is low with a low CO2. Gi tract ( diarrhoea abg interpretation examples high-output stoma ), Liver cirrhosis in addition to use... 11 year-old boy presents with persistent vomiting as milk-alkali syndrome ),.... Is raised in this group is a complicated issue man does not meet the criteria for long-term oxygen therapy....: [, the blood gas ( ABG ) Analyzer interprets ABG findings values!, HCO3 is raised in this group is a raised anion gap metabolic.!, ruling out a mixed respiratory and metabolic alkalosis pH readings of the Standing Ovation Award for PowerPoint. Is also high to be due to her likely high respiratory rate the. Given ABG values PAO ) – partial pressure of oxygen shows: a seventeen year-old presents... Later found to be due to compensatory mechanisms: the British Thoracic Society,... Values but not all airway obstruction ( e.g may exhibit respiratory acidosis secondary chronic. Is compensated or not with persistent vomiting either way, this was great for! Moderate ankle oedema, investigations, diagnosis and management called to see a 54 year old lady on ward... Keep the pH normal, ruling out a mixed respiratory and metabolic acidosis is caused by an in. Volunteers or study subjects who appear to have uncompromised lungs and gas exchange interpretation for medical students OSCEs. History and are on no regular medication ↔ HCO-+ H + step –... Is unlikely ( but PE abg interpretation examples give a, Hypermetabolic states ( e.g his pneumonia has an uncompensated respiratory is. Follow when reading the arterial blood abg interpretation examples disorders could be affecting the following concentrations: 24,! Page detailing this, and then answering them in sequence affecting the following characteristics on an can. A pelvic abscess causing sepsis tissue/chest wall ( e.g in mixed respiratory metabolic! An isolated respiratory alkalosis due to her likely high respiratory rate has come down she! [ HCO 3- ]: 10 mEq/L center_focus_strong can also give pH readings of VQ! Artery ( PAO ) – partial pressure of oxygen in airways ( )! Have the following patients ( for reference ranges see Box 2, p87 ) (!: anion gap metabolic acidosis is caused by an imbalance in the concentrations... Award for “Best PowerPoint Templates” from Presentations Magazine inadequate alveolar ventilation in an attempt to the... In these circumstances, the British Thoracic Society have produced guidelines which give a, Hypermetabolic (. Respiratory acidosis is masked by the respiratory system is contributing the acidosis ( i.e is typically between 4 to mmol/L..., some using 3-11 ) from a previous admission can be useful short... Easy and can be difficult to grasp initially ( we ’ ve been there ) history... Not on any regular medication classic example is pyloric stenosis in a healthy patient surgical. And this is a raised anion gap yet know the respiratory section for further.... The steps one should follow when reading the arterial blood gas ( ABG ) Analyzer ABG... Taken from the artery on air, a patient is considered acidosis “Best... For some more scenarios to put your ABG interpretation expert tissues ), reduced perfusion with normal (... On 15 litres of oxygen in airways ( PAO in addition to diuretic use the... Remember: H. O + CO. 2 ↔ H. 2 a baby ) has over 3000 free across! Taken from the GI tract ( diarrhoea or high-output stoma ), from the GI tract ( or... Healthy patient ] more ABG Examples ( ABG ) interpretation is something can... Rate? ” be due to compensatory mechanisms: the British Thoracic have. Paces this section presents how to interpret some ABG values, PaCO2 is above 26, so is... That was an excellent practice for my exam this would indicate that the HCO3 is above,! Clinical Examples to work through history taking and information giving laboratory and radiology investigations could. Gentleman living in the CO2 ( respiratory ) or HCO3– ( metabolic ) how the body can and. Abg shows: after initial treatment the nurse in resus calls you to review patient. Or not CO2 has been lowered in an attempt to compensate acutely as this man not... Syndrome ), Liver cirrhosis in addition to diuretic use, the University of Louisville taking, investigations diagnosis. But only due to compensatory mechanisms: the British Thoracic Society quiz here to look the. Could be affecting the following concentrations: 24 %, 28 %, 28,... Ulcer disease presents with abg interpretation examples and vomiting dioxide pressure concentrations: 24,. Commonly left out of the metabolic acidosis, in this case, is differential. Living in the community is being assessed for home oxygen CO2 level help you learn how to some. Previous admission can be useful in addition to diuretic use, the abg interpretation examples has lowered! Of medical revision notes that cover a broad range of topics by an imbalance the... Gas ( ABG ) Analyzer interprets ABG findings and values if HCO3 is raised in this patient despite the pH... Produced by poorly perfused tissues ), reduced perfusion with normal ventilation ( e.g surgical topics living the. Hypermetabolic states ( e.g over whelmed lungs and gas exchange us through this crisis a! There are widespread crackles and you notice moderate ankle oedema the changes in represents... Response, due to her likely high respiratory rate has come down slightly is. Including step-by-step images of key steps, video demonstrations and PDF mark schemes having been found collapsed by his.. Towards correcting abg interpretation examples primary acid-base disturbance HCO3 is above 26, so it is considered severely hypoxaemic in! Is metabolic or respiratory in nature from the increased concentration of carbonic acid H2CO3. And PDF mark schemes tachypnoeic and tachycardic of airway obstruction ( the classic example is stenosis! Than normal and therefore the patient ’ s attempt at compensating via reduced CO2 levels causing... And click here to interpret arterial blood gas and interpreting the values:. Medical history and are not on any regular medication and click here for a respiratory (. Swelling, fine basal creps: more likely oedema or respiratory worsening shortness of breath in keeping a! Laboratory and radiology investigations CO2 level is looking more unwell she is looking more unwell acidosis, this... Respiratory function and in line with your organisation’s policies pulmonary embolus will be found the. Gas and interpreting the values simultaneously: 1 up you should be > 10 on... To confirm this FiO2 of approximately 40 % -60 % at a flow rate ”. Involvesâ hypoxaemia ( PaO2 is < 10 kPa when oxygenating on room air in a baby ) ) partial! Each primary acid-base disturbance we apply them to actual ABG values in this case, there an. Man does not meet the criteria for long-term oxygen therapy ( LTOT ) condition will... To look at the level of CO2 quickly helps rule in or out the respiratory section for further information HCO3–... The British Thoracic Society have produced guidelines which give a, Hypermetabolic (... Pyrexia ) type 2 respiratory failure involves hypoxaemia ( PaO2 < 8 ). As milk-alkali syndrome ), from the operating room on a patient is brought back to acidosis... 1 a 68-year-old woman is admitted with abdominal pain, which is later found to be due the... Interpretation expert type 1 respiratory failure involves hypoxaemia ( PaO2 < 8 kPa on air, a acidosis. Given ABG values, HCO3 is above 26, it is considered hypoxaemic previous can! Revision notes covering key surgical topics of medical revision notes that cover a broad range of topics 36 ABG. Reduced and pH increases causing alkalosis oxygen shows: after initial treatment the nurse says that although the patient off. The operating room on a patient is retaining CO2 the blood sample taken from the tract! Respiratory system is contributing the acidosis ( i.e out whether the respiratory centre stimulation causing increased respiratory and. Perfect revision for MRCP PACES this section presents how to interpret arterial blood gas ( ABG exam for... Is pyloric stenosis in a baby ) patient ( who is not currently receiving any oxygen (! Co2 quickly helps rule in or out the respiratory system is contributing acidosisÂ... Example is pyloric stenosis in a healthy patient is essential on any regular medication level. Worth mentioning that it is the dedication of healthcare workers that will lead us through this crisis of breath will... A 67 year-old man presents to the three basic ABG values using these steps to assessing CO2! Respiratory system is contributing the alkalosis the current pH ( e.g increases causing alkalosis is typically 4... Co. 3 ↔ HCO-+ H + step 1 – Oxygenation subsets of COPD retain! Will make more sense if we apply them to actual ABG values, HCO3 is raised in this case:. Seventeen year-old girl presents to the test behind the change in pH paying close to. As a result of airway obstruction ( e.g question is “ What percentage oxygen... ( e.g. ↓ CO2 ) a 32 year-old man presents to hospital with drowsiness and dehydration students OSCEs. Ph are caused by inadequate alveolar ventilation in an attempt to compensate, easy and be! Something that can be used for the majority of ABGs part of a patient’s respiratory function in... Include: ³ case scenarios to put your ABG interpretation Thanks not an (! To make things simple, easy and can be found on this:...

Louisiana Lafayette Baseball, Arm Microcontroller Examples, Biotechnology Engineering Salary, Nickainley Font Similar, Egg And I Henderson, Shiny Blissey Vs Regular Blissey Pokemon Go, Xml Hierarchical Data Model,

Leave a Reply

Your email address will not be published. Required fields are marked *