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Compensated Metabolic Acidosis Example

Acid-base Tutorial - Interpretation

Acid-base Tutorial - Interpretation

by "Grog" (Alan W. Grogono), Professor Emeritus, Tulane University Department of Anesthesiology What is a moderate interpretation of the text? Halfway between what it really means and what you would like it to mean? - Antonin Scalia. This page describes the interpretation of the acid-base component of blood gas results. Designing the interactive acid-base diagram necessitated the development of a logical approach. This page converts the logic back into a human process. Constraints of Not Knowing Patient Details: In a Perfect World complete information about a patient is available before acid-base values are analyzed. What follows is a logical framework for looking at acid-base values with no patient. Reports may say that the results are "typical of" or "characteristic of" a single clinical problem. However, identical results can also be obtained from a complex combination of clinical problems. Step 1: Is the pH normal, acid, or alkaline critical because it governs all the subsequent thinking. In acute problems the change is usually acidic - a low pH - e.g., 7.2 or 7.1. This is because failure, either respiratory or metabolic, results in the accumulation of acids. The following paragraphs assume the result is acid. However, also look at the Table of Details which follows the paragraphs below. Step 2: If the respiratory change is also acid (raised PCO2), then the cause is respiratory, unless the metabolic component is also acidic in which case both are contributing to the acidic pH. If the PCO2 is not like the pH, i.e., the PCO2 is low (alkaline), then the primary problem must be metabolic and the low PCO2 is compensating for the metabolic acidosis. Standard Base Excess - the Metabolic Component: Step 3: If the Standard Base Excess (SBE) is acidic (a negative SBE), then Continue reading >>

Acidosis

Acidosis

For acidosis referring to acidity of the urine, see renal tubular acidosis. "Acidemia" redirects here. It is not to be confused with Academia. Acidosis is a process causing increased acidity in the blood and other body tissues (i.e., an increased hydrogen ion concentration). If not further qualified, it usually refers to acidity of the blood plasma. The term acidemia describes the state of low blood pH, while acidosis is used to describe the processes leading to these states. Nevertheless, the terms are sometimes used interchangeably. The distinction may be relevant where a patient has factors causing both acidosis and alkalosis, wherein the relative severity of both determines whether the result is a high, low, or normal pH. Acidosis is said to occur when arterial pH falls below 7.35 (except in the fetus – see below), while its counterpart (alkalosis) occurs at a pH over 7.45. Arterial blood gas analysis and other tests are required to separate the main causes. The rate of cellular metabolic activity affects and, at the same time, is affected by the pH of the body fluids. In mammals, the normal pH of arterial blood lies between 7.35 and 7.50 depending on the species (e.g., healthy human-arterial blood pH varies between 7.35 and 7.45). Blood pH values compatible with life in mammals are limited to a pH range between 6.8 and 7.8. Changes in the pH of arterial blood (and therefore the extracellular fluid) outside this range result in irreversible cell damage.[1] Signs and symptoms[edit] General symptoms of acidosis.[2] These usually accompany symptoms of another primary defect (respiratory or metabolic). Nervous system involvement may be seen with acidosis and occurs more often with respiratory acidosis than with metabolic acidosis. Signs and symptoms that may be seen i Continue reading >>

Arterial Blood Gas (abg) Interpretation For Medical Students, Osces And Mrcp Paces

Arterial Blood Gas (abg) Interpretation For Medical Students, Osces And Mrcp Paces

Arterial Blood Gas (ABG) interpretation for medical students, OSCEs and MRCP Arterial Blood Gas (ABG) interpretation for medical students, OSCEs and MRCP PACES This section presents how to interpret arterial blood gases. It explains each component in turn followed by clinical examples to work through. The most important points when assessing a patient are the history, examination and basic observations. Investigations such as arterial blood gases add to the information you have already gained to guide your management. Arterial blood gas analysis can be used to assess gas exchange and acid base status as well as to provide immediate information about electrolytes. It is also useful to have access to any previous gases. This is particularly important if your patient is known to have chronic respiratory disease with existing chronic ABG changes. Normal values for arterial blood gas (ABG) Normal values are given below. Note that these may vary slightly between analysers. Be sure to know the normal ranges and units for the analyser you will be using. Click here for related pages: ABG examples and ABG exam questions pH is a logarithmic scale of the concentration of hydrogen ions in a solution. It is inversely proportional to the concentration of hydrogen ions. When a solution becomes more acidic the concentration of hydrogen ions increases and the pH falls. Normally the bodys pH is closely controlled at between 7.35 7.45. This is achieved through buffering and excretion of acids. Buffers include plasma proteins and bicarbonate (extracellular) and proteins, phosphate and haemoglobin (intracellularly). Hydrogen ions are excreted via the kidney and carbon dioxide is excreted via the lungs. Changes in ventilation are the primary way in which the concentration of H+ ions is regul Continue reading >>

5.5 Metabolic Acidosis - Compensation

5.5 Metabolic Acidosis - Compensation

Acid-Base Physiology 5.5.1 Hyperventilation Compensation for a metabolic acidosis is hyperventilation to decrease the arterial pCO2. This hyperventilation was first described by Kussmaul in patients with diabetic ketoacidosis in 1874. The metabolic acidosis is detected by both the peripheral and central chemoreceptors and the respiratory center is stimulated. The initial stimulation of the central chemoreceptors is due to small increases in brain ISF [H+]. The subsequent increase in ventilation causes a fall in arterial pCO2 which inhibits the ventilatory response. Maximal compensation takes 12 to 24 hours The chemoreceptor inhibition acts to limit and delay the full ventilatory response until bicarbonate shifts have stabilised across the blood brain barrier. The increase in ventilation usually starts within minutes and is usually well advanced at 2 hours of onset but maximal compensation may take 12 to 24 hours to develop. This is �maximal� compensation rather than �full� compensation as it does not return the extracellular pH to normal. In situations where a metabolic acidosis develops rapidly and is short-lived there is usually little time for much compensatory ventilatory response to occur. An example is the acute and sometimes severe lactic acidosis due to a prolonged generalised convulsion: this corrects due to rapid hepatic uptake and metabolism of the lactate following cessation of convulsive muscular activity, and hyperventilation due to the acidosis does not occur. The expected pCO2 at maximal compensation can be calculated from a simple formula The arterial pCO2 at maximal compensation has been measured in many patients with a metabolic acidosis. A consistent relationship between bicarbonate level and pCO2 has been found. It can be estimated from the Continue reading >>

Arterial Blood Gas - Abg - Interpretation | Almostadoctor

Arterial Blood Gas - Abg - Interpretation | Almostadoctor

Most commonly cause by diarrhoea . In diarrhoea , there is a loss of K+ into the GI tract. This causes K+ to leave cells, and enter the bloodstream in an attempt to keep K+ levels normal. In order to maintain the electrical charge of the cell, H+ is then taken up by the cell. Normal kidneys are very effective at excreting bicarbonate. Diuretics prevent the re-absorption of sodium from the renal tubule, and thus they promote sodium loss. The normal mechanism for recovering this sodium , involves an exchange with bicarbonate, and thus the ability of the renal tubule to excret bicarbonate is reduced. May also be cause by too much bicarbonate (sometimes iatrogenic) or ingestion of other alkaline substances. Metabolic acidosis is the most common and the most complex of the acid base disturbances. There are a wide variety of causes, which can be differentiated with the help of the anion gap. This is used to help diagnose acid base disorders. It is usually used in suspected cases ofmetabolic acidosis. It can either be normal, or raised. Low anion gap does not usually occur. Anions are negatively charged ions.The two most common ones in the human body are chloride and bicarbonate. Anions are hard to measure accurately.The anion gap is thedifference between the number of measured anions, and the number of unmeasured anions. Negatively chargedproteinsmake up most of the unmeasured anions in a normal individual, and the main one is albumin. And thus in a normal individual, there is an anion gap of 4-16, made up mostly of albumin.Some causes of metabolic acidosis, do not produce a large number of unmeasured anions, and the anion gap doesnt increase. This isnormal anion gap metabolic acidosis NAGMA Some causes of metabolic acidosis produce a large number of both measured (e.g. HCO3 Continue reading >>

Abg Interpreter

Abg Interpreter

pH CO2 HCO3 Result appears in here. Normal Arterial Blood Gas Values pH 7.35-7.45 PaCO2 35-45 mm Hg PaO2 80-95 mm Hg HCO3 22-26 mEq/L O2 Saturation 95-99% BE +/- 1 Four-Step Guide to ABG Analysis Is the pH normal, acidotic or alkalotic? Are the pCO2 or HCO3 abnormal? Which one appears to influence the pH? If both the pCO2 and HCO3 are abnormal, the one which deviates most from the norm is most likely causing an abnormal pH. Check the pO2. Is the patient hypoxic? I used Swearingen's handbook (1990) to base the results of this calculator. The book makes the distinction between acute and chronic disorders based on symptoms from identical ABGs. This calculator only differentiates between acute (pH abnormal) and compensated (pH normal). Compensation can be seen when both the PCO2 and HCO3 rise or fall together to maintain a normal pH. Part compensation occurs when the PCO2 and HCO3 rise or fall together but the pH remains abnormal. This indicates a compensatory mechanism attempted to restore a normal pH. I have not put exact limits into the calculator. For example, it will perceive respiratory acidosis as any pH < 7.35 and any CO2 > 45 (i.e. a pH of 1 and CO2 of 1000). These results do not naturally occur. pH PaCO2 HCO3 Respiratory Acidosis Acute < 7.35 > 45 Normal Partly Compensated < 7.35 > 45 > 26 Compensated Normal > 45 > 26 Respiratory Alkalosis Acute > 7.45 < 35 Normal Partly Compensated > 7.45 < 35 < 22 Compensated Normal < 35 < 22 Metabolic Acidosis Acute < 7.35 Normal < 22 Partly Compensated < 7.35 < 35 < 22 Compensated Normal < 35 < 22 Metabolic Alkalosis Acute > 7.45 Normal > 26 Partly Compensated > 7.45 > 45 > 26 Compensated Normal > 45 > 26 Mixed Disorders It's possible to have more than one disorder influencing blood gas values. For example ABG's with an alkale Continue reading >>

Uncompensated, Partially Compensated, Or Combined Abg Problems

Uncompensated, Partially Compensated, Or Combined Abg Problems

Arterial Blood Gas (ABG) analysis requires in-depth expertise. If the results are not understood right, or are wrongly interpreted, it can result in wrong diagnosis and end up in an inappropriate management of the patient. ABG analysis is carried out when the patient is dealing with the following conditions: • Breathing problems • Lung diseases (asthma, cystic fibrosis, COPD) • Heart failure • Kidney failure ABG reports help in answering the following questions: 1. Is there acidosis or alkalosis? 2. If acidosis is present, whether it is in an uncompensated state, partially compensated state, or in fully compensated state? 3. Whether acidosis is respiratory or metabolic? ABG reports provide the following descriptions: PaCO2 (partial pressure of dissolved CO2 in the blood) and PaO2 (partial pressure of dissolved O2 in the blood) describe the efficiency of exchange of gas in the alveolar level into the blood. Any change in these levels causes changes in the pH. HCO3 (bicarbonate in the blood) maintains the pH of the blood within normal range by compensatory mechanisms, which is either by retaining or increasing HCO3 excretion by the kidney. When PaCO2 increases, HCO3 decreases to compensate the pH. The following table summarizes the changes: ABG can be interpreted using the following analysis points: Finding acidosis or alkalosis: • If pH is more it is acidosis, if pH is less it is alkalosis. Finding compensated, partially compensated, or uncompensated ABG problems: • When PaCO2 is high, but pH is normal instead of being acidic, and if HCO3 levels are also increased, then it means that the compensatory mechanism has retained more HCO3 to maintain the pH. • When PaCO2 and HCO3 values are high but pH is acidic, then it indicates partial compensation. It means t Continue reading >>

More Abg Examples - Resus

More Abg Examples - Resus

This is an elderly man with vomiting for 3 days, who presents with tachycardia. It would be expected that there be a metabolic alkalosis with loss of gastric contents. His pH shows an alkalosis and he has raised bicarb. He is hypokalaemic and hypocloraemic, with a raised BSL. The Na is low, when corrected for increased BSL it is 134. With this metabolic alkalosis the expected pCO2 is (0.9 x HCO3) + 16 = 43. The actual pCO2 is 28.5. Therefore this is a mixed picture ofMetabolic and Respiratory Alkalosis i.e.,he has his metabolic alkalosis but is also breathing up more than he should. Expected Aa gradient is age/4 +4 = 22.5 so a very high Aa gradient indicating a V/Q mismatch, or diffusion defect. So when we think of causes, take both things into account- the vomiting and the Aa. Pneumonia(although afebrile- elderly may be) A 21 year old man is brought in by his father with a one week history of vomiting. He has not been able to keep any food down. He has been diagnosed with Hashimotos thyroiditis by his local doctor 4 months previously. Today his blood pressure is 90/48 and pulse rate 104. These are his venous blood gas results: Is it acidosis or alkalosis? ACIDOSIS What is the primary cause? Given the low HCO3 and the not so high pCO2 it isMETABOLIC ACIDOSIS. Expected pCO2 is [(1.5xHCO3) +8]+2 i.e.., [(~30) + 8]+2 = 38-39 sothere is adequate compensation Na -(Cl + HCO3) = 108-(72 + 19) = 17 so raised anion gap metabolic acidosis. (reference is 8-16) Is there any other process going on? Look at the delta gap. change in AG/change in HCO3 = 17-12(use 12 as the expected AG)/24-19(24 is the expected HCO3) = 5/5 = 1 so this is a pure anion gap metabolic acidosis. ( Given what I say below, I might have also expected a normal anion gap metabolic acidosis) The Na is very low an Continue reading >>

Arterial Blood Gases - Indications And Interpretation

Arterial Blood Gases - Indications And Interpretation

Severely unwell patients from any cause - affects prognosis. Arterial blood can be obtained by direct arterial puncture most usually at the wrist (radial artery). Alternatives to the radial artery include the femoral and brachial artery - both of which are usually used in emergency settings. The dorsalis pedis artery and ulnar artery may also be used. It is important to ensure good collateral circulation (see below), as there is a theoretical risk of thrombus occlusion. If multiple samples are required then an indwelling arterial cannula can be placed. Allow the patient to titrate with the oxygen for 5-10 minutes (30 minutes if they have chronic obstructive pulmonary disease (COPD)) before taking a sample. If the radial artery is to be used, perform Allen's test to confirm collateral blood flow to the hand. Elevate the hand and make a fist for approximately 30 seconds. Apply pressure over the ulnar and the radial arteries occluding both (keep the hand elevated). Release pressure on the ulnar artery and look for perfusion of the hand (this takes under eight seconds). If there is any delay then it may not be safe to perform radial artery puncture. Explain the procedure to the patient - it is painful. If there is time then local anaesthesia can be used. ABG syringes usually come prepacked and are heparinised. Some contain a vacuum and thus the plunger does not always need to be pulled. (Check with your department as to which they use). The wrist is extended - a pillow under the hand may improve comfort. Palpate the artery and hold fingers firmly over the pulsation. Then introduce the needle at a 45 angle slowly with the bevel facing upwards, aiming for the point of maximum pulsation. Once you hit the artery, try to obtain at least a 1 ml sample. Once you have taken your s Continue reading >>

The Abcs Of Abgs: Blood Gas Analysis

The Abcs Of Abgs: Blood Gas Analysis

A systematic and step-wise process based upon pH shift is the key to correct interpretation and application of arterial blood gas results In a previous article, “The Pitfalls of Arterial Blood Gases” (RT, April 2013), I described how simple pre-analytical, analytical, and post-analytical errors can produce arterial blood gas test results (ABGs) that are of little or no value, and perhaps even dangerous. In this article, I will assume that we have avoided all of those pitfalls and and will discuss how to interpret valid ABG results. (Some of the foundational information in this article is necessary for those new to interpreting. I encourage more experienced practitioners to bear with me.) This article will not attempt to discuss all of the possible causes or disease states that could relate to the results. Neither will it attempt to go into the interpretation of electrolytes or co-oximetry results. Adequate review of these subjects could require—in fact, have required—whole textbooks, and are beyond the scope of this article. What Is Normal? To interpret ABGs, we first need to know the normal values for the various analytes. Where do these normal values come from? They mostly come from collected results of volunteers or study subjects who appear to have uncompromised lungs and gas exchange. 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. Whichever range you and your facility prefer, it is important to think in terms of a normal range, not a single, specific, always “normal” value—except when it comes to pH for interpreting acid-base balance. We will get to why shortly. It is also vital to remember that the aggregate “normal” value is a con Continue reading >>

Abg Interpretation

Abg Interpretation

Arterial blood gas (ABG) interpretation is something many medical students find difficult to grasp (we’ve been there). We’ve created this guide, which aims to provide a structured approach to ABG interpretation whilst also increasing your understanding of each results relevance. 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. To see how to perform an arterial blood gas check out our guide here. If you want to put your ABG interpretation skills to the test, check out our ABG quiz here. Normal ranges pH: 7.35 – 7.45 PaCO2: 4.7-6.0 kPa PaO2: 11-13 kPa HCO3-: 22-26 mEg/L Base excess: -2 to +2 mmol/L Patient’s clinical condition Before getting stuck into the details of the analysis, it’s important to look at the patient’s current clinical status, as this provides essential context to the ABG result. Below are a few examples to demonstrate how important context is when interpreting an ABG. A normal PaO2 in a patient on high flow oxygen – this is abnormal as you would expect the patient to have a PaO2 well above the normal range with this level of oxygen therapy A normal PaCO2 in a hypoxic asthmatic patient – a sign they are tiring and need ITU intervention A very low PaO2 in a patient who looks completely well, is not short of breath and has normal O2 saturations – likely a venous sample Oxygenation (PaO2) Your first question when looking at the ABG should be “Is this patient hypoxic?” (because this will kill them long before anything else does). PaO2 should be >10 kPa on air in a healthy patient If the patient is receiving oxygen therapy their PaO2 should be approximately 10kPa less than the % inspired concentration / FiO Continue reading >>

Partially Compensated Vs. Fully Compensated Abgs Practice

Partially Compensated Vs. Fully Compensated Abgs Practice

This is an NCLEX practice question on partially compensated vs fully compensated ABGs. This question provides a scenario about arterial blood gas results. As the nurse, you must determine if this is a respiratory or metabolic problem, alkalosis or acidosis along with if it is uncompensated, partially or fully compensated based on the results. This question is one of the many questions we will be practicing in our new series called “Weekly NCLEX Question”. So, every week be sure to tune into our YouTube Channel for the NCLEX Question of the Week. More NCLEX Weekly Practice Questions. To solve ABGs problems, I like to use the Tic Tac Toe method. If you are not familiar with this method, please watch my video on how to solve arterial blood gas problems with this method. The Tic Tac Toe method makes solving ABG problems so EASY. However, if the ABG values are partially or fully compensated you must take it a step further by analyzing the values further with this method, which is the purpose of this review. My goal is to show you how to use the Tic Tac Toe method for partially and fully compensated interpretation. So let’s begin: NCLEX Practice Questions on Partially vs. Fully Compensated ABGs Problem 1 A patient has the following arterial blood gas results: blood pH 7.43, PaCO2 28 mmHg, and HCO3 18 mEq/L. This is known as: A. Partially compensated respiratory alkalosis B. Fully compensated metabolic acidosis C. Partially compensated respiratory acidosis D. Fully compensated respiratory alkalosis The first thing you want to do is to pull from your memory bank the normal values for arterial blood gases. Here they are: <-Acid Base-> pH: 7.35-7.45 (less than 7.35 ACID & greater than 7.45 ALKALOTIC) PaCO2: 45-35 (greater than 45 ACID & less than 35 ALKALOTIC)** HCO3: 22-26 Continue reading >>

Perfecting Your Acid-base Balancing Act

Perfecting Your Acid-base Balancing Act

When it comes to acids and bases, the difference between life and death is balance. The body’s acid-base balance depends on some delicately balanced chemical reactions. The hydrogen ion (H+) affects pH, and pH regulation influences the speed of cellular reactions, cell function, cell permeability, and the very integrity of cell structure. When an imbalance develops, you can detect it quickly by knowing how to assess your patient and interpret arterial blood gas (ABG) values. And you can restore the balance by targeting your interventions to the specific acid-base disorder you find. Basics of acid-base balance Before assessing a patient’s acid-base balance, you need to understand how the H+ affects acids, bases, and pH. An acid is a substance that can donate H+ to a base. Examples include hydrochloric acid, nitric acid, ammonium ion, lactic acid, acetic acid, and carbonic acid (H2CO3). A base is a substance that can accept or bind H+. Examples include ammonia, lactate, acetate, and bicarbonate (HCO3-). pH reflects the overall H+ concentration in body fluids. The higher the number of H+ in the blood, the lower the pH; and the lower the number of H+, the higher the pH. A solution containing more base than acid has fewer H+ and a higher pH. A solution containing more acid than base has more H+ and a lower pH. The pH of water (H2O), 7.4, is considered neutral. The pH of blood is slightly alkaline and has a normal range of 7.35 to 7.45. For normal enzyme and cell function and normal metabolism, the blood’s pH must remain in this narrow range. If the blood is acidic, the force of cardiac contractions diminishes. If the blood is alkaline, neuromuscular function becomes impaired. A blood pH below 6.8 or above 7.8 is usually fatal. pH also reflects the balance between the p Continue reading >>

The Interpretation Of Arterial Blood Gases

The Interpretation Of Arterial Blood Gases

The interpretation of arterial blood gases The interpretation of arterial blood gases Aust Prescr 2010;33:124-91 Aug 2010DOI: 10.18773/austprescr.2010.059 Arterial blood gas analysis is used to measure the pH and the partial pressures of oxygen and carbon dioxide in arterial blood. The investigation is relatively easy to perform and yields information that can guide the management of acute and chronic illnesses.This information indicates a patient's acid-base balance, the effectiveness of their gas exchange and the state of their ventilatory control. Interpretation of an arterial blood gas result should not be done without considering the clinical findings.The results change as the body compensates for the underlying problem. Factors relating to sampling technique, specimen processing and environment may also influence the results. Arterial blood gas analysis is a common investigation in emergency departments and intensive care units for monitoring patients with acute respiratory failure. It also has some application in general practice, such as assessing the need for domiciliary oxygen therapy in patients with chronic obstructive pulmonary disease. An arterial blood gas result can help in the assessment of a patient's gas exchange, ventilatory control and acidbase balance. However, the investigation does not give a diagnosis and should not be used as a screening test. It is imperative that the results are considered in the context of the patient's symptoms. While non-invasive monitoring of pulmonary function, such as pulse oximetry, is simple, effective and increasingly widely used, pulse oximetry is no substitute for arterial blood gas analysis. Pulse oximetry is solely a measure of oxygen saturation and gives no indication about blood pH, carbon dioxide or bicarbona Continue reading >>

Metabolic Acidosis

Metabolic Acidosis

Metabolic acidosis is a condition that occurs when the body produces excessive quantities of acid or when the kidneys are not removing enough acid from the body. If unchecked, metabolic acidosis leads to acidemia, i.e., blood pH is low (less than 7.35) due to increased production of hydrogen ions by the body or the inability of the body to form bicarbonate (HCO3−) in the kidney. Its causes are diverse, and its consequences can be serious, including coma and death. Together with respiratory acidosis, it is one of the two general causes of acidemia. Terminology : Acidosis refers to a process that causes a low pH in blood and tissues. Acidemia refers specifically to a low pH in the blood. In most cases, acidosis occurs first for reasons explained below. Free hydrogen ions then diffuse into the blood, lowering the pH. Arterial blood gas analysis detects acidemia (pH lower than 7.35). When acidemia is present, acidosis is presumed. Signs and symptoms[edit] Symptoms are not specific, and diagnosis can be difficult unless the patient presents with clear indications for arterial blood gas sampling. Symptoms may include chest pain, palpitations, headache, altered mental status such as severe anxiety due to hypoxia, decreased visual acuity, nausea, vomiting, abdominal pain, altered appetite and weight gain, muscle weakness, bone pain, and joint pain. Those in metabolic acidosis may exhibit deep, rapid breathing called Kussmaul respirations which is classically associated with diabetic ketoacidosis. Rapid deep breaths increase the amount of carbon dioxide exhaled, thus lowering the serum carbon dioxide levels, resulting in some degree of compensation. Overcompensation via respiratory alkalosis to form an alkalemia does not occur. Extreme acidemia leads to neurological and cardia Continue reading >>

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