Look at the ph and decide whether its value is acidotic, normal, or alkalotic. Arterial blood gas abg interpretation almostadoctor. Partial compensation ph is still abnormal, and the other value is abnormal in an attempt to help normalise the ph. Abg tests are used to evaluate respiratory and kidney functions and give an overall look into the bodys metabolic state. Critical values abgs any abg value marked as outside of normal range will be considered a critical value unless otherwise defined, designated or ordered by the physician. If the ph is not in the normal range and the abg is not trying to correct itself then the compensation result is. Abg results may indicate decreased o2 levels hypoxia, decreased or increased co2 levels hypo or hypercapnia, acidosis decreased ph, alkalosis increased ph. Finally, bicarbonate ions, or hco 3, will tell you if the problem is related to metabolic changes in your patient and refers to the renal system berman et al. An abg test requires that a small volume of blood be drawn from the radial artery with a syringe and a thin needle, but sometimes the femoral artery in the groin or another site is used. Critical value reporting turnaround time tat in general, all reporting of abg critical values occurs within 15 minutes. Apr 06, 2020 ed4nurses abg pdf practice abg case studies from 1. Both the ph and the co2 values are abnormal and match. Look at the chart below to determine the evaluation or abnormal values. So2 may be as low as 90% in healthy patients of advanced age.
Normal is 3545mmhg hypercapnoea is 45 mmhg and is reflective of hypoventilation hypocapnoea is abg and cbc normal values. An arterialblood gas abg test measures the amounts of arterial gases, such as oxygen and carbon dioxide. This table lists reference values for the most common laboratory tests and is intended for interpretation of the results as they are provided in the examination. To ensure that patients receive optimal management when they require or have an arterial blood pressure device in situ. Interpretation of arterial blood gases abgs david a. The arterial blood gas provides the following values. Abg interpretation what numbers do you get on an abg. An old beggar was admitted to the emergency department due to shortness of breath, fever, and a productive cough. Abg values based on neonatal age prebirth 5 min 17 days scalp after birth after birth. Abgs provide information about acidbase balance and the levels of o2 and co2 in the blood. This is an indicator of the total buffer base of the body.
This determines if the blood is acidotic or alkalotic. Arterial blood gases values normal ranges and procedure. Fio2 the percentage of inspired oxygen that you took the blood gas on ph normal range 7. Interpreting an arterial blood gas abg is a crucial skill for physicians, nurses, respiratory. However, during the first three months of life ph was 0,02 units lower than during the 4th to 12th month.
Record the one in the normal range as ph1 recalculate ph using the exact midpoint of the normal range, or 7. If the ph remains abnormal, the com pensation is partial. Abg examples abg exam questions for medical students osces and mrcp paces below are some brief clinical scenarios with abg results. Interpreting the information obtained from an abg result, combined with the patients history and our knowledge of normal pathophysiology as it applies to acidbase balance will help us to plan how to resolve the problem lippincott, 2012. The abg is one of the most basic tests we run in the emergency department. Subsequently, all values will be assumed to be arterial.
Abg reference indications for abg identify and monitor acidbase imbalances measure pao2 and paco2 assess response to interventions eg, dka, copd measure levels of abnormal hemoglobins blood sampling when venous sampling unavailable abg normal values ph paco2 pao2 hco3 o2 % 7. Critical values are called to the clinician responsible for the patient. Abg interpretation a guide to understanding abgs geeky medics. Note that these may vary slightly between analysers. This is a measure of the % of oxygen that is attached to hemoglobin in red blood cells. Extra oxygen, however, cannot be absorbed without giving a higher oxygen concentration because the maximum amount of oxygen diffuses across the alveolar membrane in normal circumstances anyway. Please refer to intermountain laboratory services labnet cp0008a1 or contact client services 8015072110 or 8773531106 for the most current critical values list. Normal values for arterial blood gas abg normal values are given below. The mean of the arterial ph values in the entire group corresponds to the normal adult values. Arterial blood gas abg interpretation for medical students. Normal is 95% in healthy humans avg is 98% for a healthy pt. Blood gases medical tests ucsf benioff childrens hospital. Continuing from the above example, the abg now reads 7.
Partial compensation ph is still abnormal, and the other value is abnormal in an. Arterial blood gas abg reference normal predicted values. Arterial blood gas abg interpretation for medical students, osces. In order to understand and interpret abgs one has to have a clear. The blood can also be drawn from an arterial catheter an abg test measures the blood gas tension. The first value is the ph, which measures how many hydrogen ions are in the sample. The normal values noted herecalled a recommendation rangeare just a guide. Arterial blood gases abgs lab and diagnostic procedure. Abg predicted normal values arterial blood gas analysis is important in managing patients with cardiopulmonary diseases. The normal values for acidbase parameters are as follows. Write the calculated ph level to the nearest onehundredth. During the calculation any change in ph due to the pco2 of the sample is eliminated, therefore, the base excess. Laboratory values see inside back cover for continuation. When cells no longer have enough o2 for normal aerobic metabolism cell hypoxia anaerobic metabolism takes over resulting in lactate production, leading to lactic acidosis 0.
Acid base balance university hospitals bristol nhs. Your lab may have a different range for whats normal. In abg results, so 2 is derived from po2 using the oxygenhemoglobin dissociation curve. This is particularly important if your patient is known to have chronic respiratory disease with existing chronic abg changes. An acceptable normal range of abg values of abg components are the. Sao 2 oxygen saturation pa pressure in the alveoli. Arterial blood gases abgs is a diagnostic test performed on blood taken from an artery that provides a glimpse of how much oxygen and carbon dioxide are in your blood, along with your bloods ph level. Arterial blood gas analysis for emergency medicine registrars. Body will not overcompensate when it comes to acidbase balance so. Both the ph and the hco3 values are abnormal and match. The next value is the carbon dioxide level, and this will tell you. Crapo et al 1 defined reference equations in 1999 for healthy nonsmokers for arterial blood gas and co oximeter analytes at two different altitudes sea level and 1400m.
Learn vocabulary, terms, and more with flashcards, games, and other study tools. List the types of samples that can be analyzed for blood gas and analyte concentrations. These ranges vary from lab to lab and depend upon the elevation above sea level. Regardless, it is an opportunity to gain information quickly. Firstly, it is important to know what values you are looking at and what is considered normal. Your lab might have a different variety for whats normal. Jan 25, 2020 ed4nurses abg pdf practice abg case studies from 1. The ph is normal, as the other value is abnormal and has been successful in normalising the ph.
An arterial blood gas abg is a test that measures the oxygen tension pao 2, carbon dioxide tension paco 2, acidity ph, oxyhemoglobin saturation sao 2, and bicarbonate hco 3 concentration in arterial blood. A normal pao2 in a patient on high flow oxygen this is abnormal as you. In cases where blood gas values do not fall into any of the above classifications, an answer unable to determine will appear when using the interpreter. Write the calculated partial pressure of carbon dioxide paco2 expressed as a whole number. Normal values and acceptable ranges of the abg elements. Vbg can be used to guide management in preference to abg ma et al, 2003 vbg correlated with abg well. This is the first of a twopart unit on arterial blood gas abg analysis, and focuses on background information and basic interpretation of abgs where no evident compensation is taking place. Acid base balance pcc1 ccna sandra batcheler normal blood gas values values arterial venous capillary ph 7. Abg examples abg exam questions for medical students and. Ed4nurses abg pdf practice abg case studies from 1. Identify components of an arterial blood gas abg and list normal ranges for each.
The present article is an attempt for the simplified approach for the bedside interpretation of abg. At altitudes of 3,000 feet and above, the oxygen values are lower. The normal values listed herecalled a reference rangeare just a guide. An arterial blood gas, or abg for short, is a test that measures the blood levels of oxygen pao2, carbon dioxide paco2, and acidbase balance ph in the body. Oxygen saturation sao2 94 100% bicarbonate hco3 22 28 meql. Arterial blood gas abg interpretation for medical students, osces and mrcp. Explain the types of errors that can occur with blood gas analysis.
It measures the acidity ph and the levels of oxygen and carbon dioxide in arterial blood. Arterial blood gas primer clinical respiratory diseases. Some blood gas analyzers also measure the methemoglobin, carboxyhemoglobin, and hemoglobin levels. Be sure to know the normal ranges and units for the analyser you will be using. Blood gas and critical care analyte analysis chapter objectives 1. You are called to see a 54 year old lady on the ward. We spend countless hours researching various file formats and software that can open, convert, create or otherwise work with those files. As mentioned above, the hco 3 concentration is calculated from the ph and pco 2. It discusses the various components on an abg report, the normal ranges and the significance of abnormal readings.
Look for my overall approach to the abg at the end of the exercise. If the ph is not within the normal range but the abg is trying to correct itself then the compensation result is partially compensated. Below are a few examples to demonstrate how important context is when interpreting an abg. Pdf arterial blood gases abg results reflect underlying pathology and interpretation of the results are often. Try to interpret each abg and formulate a differential diagnosis before looking at the answer. Interpreting abgs arterial blood gases made easy ausmed. Before getting stuck into the details of the analysis, its important to look at the patients current clinical status, as this provides essential context to the abg result. An arterial blood gas abg test measures the acidity ph and levels of oxygen and carbon dioxide in the blood. Its a test that is used to assess how well oxygen is being distributed throughout the body and how well carbon dioxide is being removed.
Arterial blood gas interpretation is best approached. Pdf arterial blood gases abg results reflect underlying pathology and interpretation of the results are often compounded by ongoing. Oct 18, 2019 arterial blood gas abg normal lab values. These varieties vary from lab to lab and rely on the elevation above water level. Understanding and use of blood gas analysis enables providers to interpret. A primer on arterial blood gas analysis family medicine residency.
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