2026 ATI Critical Care Proctored Exam | Acid-Base Imbalances & ABG Interpretation | Questions & Verified Answers | RN Adult Medical Surgical Critical Care | Graded A+ Study Guide

Master complex clinical scenarios with this 2026 ATI Critical Care Proctored Exam study resource. This document provides verified questions and answers focusing on high-acuity nursing care and physiological integrity. Key topics include Arterial Blood Gas (ABG) interpretation, the bicarbonate-carbonic acid buffer system, and the relationship between acidosis and potassium shifts. Students will find detailed rationales for managing increased intracranial pressure (ICP), calculating Cerebral Perfusion Pressure (CPP), and treating respiratory alkalosis caused by hyperventilation. The guide also covers critical interventions for mechanical ventilation, hemodynamic monitoring, and electrolyte imbalances. Whether you are aiming for Level 3 proficiency on your ATI proctored assessment or preparing for advanced CCRN or 2026 NCLEX-RN questions, this test bank offers the essential clinical depth and accuracy required for excellence in critical care nursing. ATI CRITICAL CARE PROCTORED EXAM 1 QUESTIONS AND ANSWERS | WITH COMPLETE SOLUTIONS A patient with an acid-base imbalance has an altered potassium level. The nurse recognizes that the potassium level is altered because a. Potassium is returned to extracellular fluid when metabolic acidosis is corrected. b. Hyperkalemia causes an alkalosis that results in potassium being shifted into the cells. c. Acidosis causes hydrogen ions in the blood to be exchanged for potassium from the cells. d. In alkalosis, potassium is shifted into extracellular fluid to bind excessive bicarbonate. A patient has the following ABG results: pH 7.48, PaO2 86 mm Hg, PaCO2 44 mm Hg, HCO3 29 mEq/L. When assessing the patient, the nurse would expect the patient to have a. Muscle cramping b. Warm, flushed skin c. Respiratory rate of 36 d. Blood pressure of 94/52 A patient with a head injury has an arterial BP of 92/50 mm Hg and ICP of 18 mm Hg. How should the nurse interpret the results? a. The CPP is so low that brain death is imminent. d. The CPP is adequate for normal cerebral blood flow. What is the most common buffer system in the body? a. Plasma protein b. Hemoglobin c. Phosphate d. Bicarbonate-carbonic acid A patient with increased ICP is positioned in a lateral position with the head of the bed elevated 30 degrees. The nurse evaluates a need for lowering the head of the bed when the patient experiences a. ptosis of the eyelid. b. unexpected vomiting. c. a decrease in motor functions. d. decreasing level of consciousness. b. The CPP is low, and the BP should be increased. c. The CPP is high, and the ICP should be reduced.Which individual is at greatest risk for experiencing a stroke? a. A 46-year-old white female with hypertension and oral contraceptive use for 10 years b. A 58-year-old white male salesman who has a total cholesterol level of 285 mg/dl c. A 42-year-old African American female with diabetes mellitus who has smoked for 30 years d. A 62-year-old African American male with hypertension who is 35 pounds overweight What are expected patient outcomes for a patient recovering from a hemorrhagic stroke? a. Exhibits absence of vasospasm b. Residual aphasia c. One to four seizures d. Complains of visual changes What intervention would not be included in aspiration precautions for a patient in the acute phase of a stroke? a. Referral to speech therapy b. Have patient tuck their chin toward the chest when swallowing c. Thickened fluids or pureed diet d. Raise HOB to 30 degrees when feeding The ventilator settings for a patient on a volume ventilator include a synchronized intermittent mandatory ventilation (SIMV) mode with 5 cm H2O PEEP. After 3 hours of ventilation, the patient's PaO2 has dropped from 82 mm Hg to 74 mm Hg. The most accurate interpretation of this finding by the nurse is that: a. The patient's respiratory rate may be decreasing, lowering the oxygen content of the blood. b. The ventilator is creating high intrathoracic pressure, suppressing venous return and cardiac output. c. The tidal volume provided by the ventilator is too high, increasing the amount of CO2 being exhaled. d. The pressure applied by PEEP requires an increased fraction of inspired oxygen (FIO2) to maintain oxygenation. Which patient is at highest risk for hypoxemic respiratory failure? a. A patient who has respiratory muscle paralysis b. A patient who has fractured ribs and a flail chest c. A patient who has a massive pulmonary embolism d. A patient who has slow breathing from a drug overdoseA patient's ABG results include pH 7.31, Paco2 50 mm Hg, Pao2 50 mm Hg, and HCO3 24 mEq/L. Oxygen is administered at 2 L/min, and the patient is placed in high-Fowler's position. An hour later, the ABGs are repeated with results of pH 7.36, Paco2 42 mm Hg, Pao2 62 mm Hg, and HCO3 24 mEq/L. What is most important for the nurse to do? a. Increase the oxygen flow rate to 4 L/min. b. Document the findings in the patient's record. c. Reposition the patient in a semi-Fowler's position. d. Prepare the patient for endotracheal intubation and mechanical ventilation. A patient with severe chronic lung disease is hospitalized with respiratory distress. Which finding would suggest to the nurse that the patient has developed rapid decompensation? a. An Spo2 of 89% b. A blood pH of 7.33 c. Agitation or confusion d. Paco2 increases from 48 to 50mm Hg When assessing a patient with sepsis, which finding would alert the nurse to the onset of acute respiratory distress syndrome (ARDS)? a. Spo2 of 90% b. Use of accessory muscles of respiration c. Fine, scattered crackles on auscultation of the chest d. ABGs of pH 7.33, Paco2 48 mm Hg, and Pao2 80 mm Hg What is a possible cause for a blood pH of 7.30? - ANSWER--metabolic acidosis (bicarb is low) -respiratory acidosis: hypoventilation (high CO2) How does your body compensate in metabolic acidosis for a pH of 7.30? - ANSWERKussmal respirations (increased rate and depth of respirations) How does your body compensate in respiratory acidosis for a pH of 7.30? - ANSWERkidneys will hold onto bicarb and excreting weak acids How would you treat pH of 7.30 due to respiratory acidosis? - ANSWER--encourage respirations (coughing, deep breathing, elevate head of bead) -if on a vent, increase rate and tidal volume How would you treat pH of 7.30 due to metabolic acidosis? - ANSWER--treat the underlying cause -give sodium bicarb What is a possible cause for a blood pH of 7.50? - ANSWER--respiratory alkalosis: hyperventilation-metabolic alkalosis: vomiting, taking a lot of antacids How does your body compensate in respiratory alkalosis for a pH of 7.50? - ANSWER-- kidneys getting rid of bicarb -cells retaining H+ ions How does your body compensate in metabolic alkalosis for a pH of 7.50? - ANSWERslow, shallow respirations What is a major concern with alkalotic states? - ANSWER-hypokalemia What is a major concern with acidotic states? - ANSWER-hyperkalemia How would you treat pH of 7.50 due to respiratory alkalosis? - ANSWER--re-breathe CO2 -treat what is causing it (anxiety) -give a benzo (lorazepam, diazepam) How would you treat pH of 7.50 due to metabolic alkalosis? - ANSWER--meds: acetazolamide (diuretic) -treat underlying issue What would be the early manifestations of ARDS? - ANSWER--change in level of consciousness -fine crackles -restlessness, anxiety -tachypnea: respiratory alkalosis with hypoxemia (because they can't oxygenate) -low CO2, low PaO2 -resistance, decreased compliance -tachycardia What are some reasons for a chest tube? - ANSWER--pneumothorax, hemothorax, tension pneumothorax -open thoracic surgery (thoracotomy) -pleural effusion -empyema -chylothorax (lymphatic fluid builds up) What are the indications of a functioning chest tube? - ANSWER--improved breath sounds -continuous gentle bubbling in the suction chamber -tidaling in water seal (fluctuates with breathing in and out) -no bubbling in the water seal chamber What are the complications of ET tubes? - ANSWER--dislodgement (would see change in respiratory status, LOC, chest symmetry)-cuff leak -ventilator associated pneumonia -vocal cord damage, laranygeal nerve damage -occluded What are the complications of tracheostomy tubes? - ANSWER--infection -tracheal necrosis -tracheal fistula/hemorrhage -nerve damage What are the causes of a high pressure alarm on a ventilator? - ANSWER--patient coughing -kinked ET tube -lots of secretions (mucus plug, condensation) -pneumothorax -increased resistance, decreased compliance What are the causes of a low pressure alarm on a ventilator? - ANSWER--air leak (tubing disconnected) -tube came out What are the possible complications of mechanical ventilation? - ANSWER--barotrauma (SQ emphysema, restless, change in LOC, SOB) -tension pneumothorax -alveolar hyper/hypoventilation -hypotension -high peep -decreased cardiac output -ventilator acquired pneumonia (VAP) What are some measure to prevent VAP? - ANSWER--infection control (washing hands) -suctioning when needed (dorsal suctioning port) -elevate HOB 45 degrees -oral care -maintaining ET cuff pressure 15-25 mmHg -sedation vacations When would we need to use PEEP? - ANSWER--to keep the alveoli open (helps with oxygenation) When would we need to use pressure support? - ANSWER--makes inspiration easier What are the complications of using positive pressure? - ANSWER--barotrauma -decreased venous return, decreased cardiac output -hypotension, tachycardia-increased afterload -decreased urinary output What are the number of twitches when using a PNS (peripheral nerve stimulator) that indicates the patient is receiving the right amount of the paralytic? - ANSWER-1-2/4 What are the signs the ventilated patient needs to be paralyzed? - ANSWER--increased RR -hear the sectretions, rhonchi on auscultation -decreased O2 saturation How is a patient with a subarachnoid hemorrhage (stroke) managed? - ANSWER-- systolic BP 100-120 -give calcium channel blocked (nimodipine) -hemodiluted -maintain ABCs -prevent spasms -DVT protocol (SCDs) -limit ICP What are the early signs of increased ICP? - ANSWER--change in level of consciousness -headache What are the late signs of increased ICP? - ANSWER-Cushings triad (irregular RR, decreased HR, widening pulse pressure) What is the acute treatment for a patient having an ischemic stroke? - ANSWER--ABCs -oxygen -history and assessment -CT w/o contrast -possibly tPA (once bleed is ruled out) What is the presentation of a patient with right brain insult? - ANSWER--left-sided weakness/hemiplegia -impulsiveness (rapid performance) -short attention span -impaired judgement and time concepts -safety problems What is the presentation of a patient with left brain insult? - ANSWER--language and comprehension issues -memory process impairment -depression -visual distrubancesWhat medications should a patient who has a TIA take daily? - ANSWER-Aspirin, Paxil, Plavix, Coumadin, Ticlid What are the complications of a patient with Guillain-Barre syndrome? - ANSWER-- numbness and tingling in lower extremities -starts working its way up the body -can impede the ability to breathe What are the complications of a patient with myasthenia gravis? - ANSWER--drooling -inability to swallow What are the mechanical ventilators weaning parameters? - ANSWER--is the underlying problem fixed? -FiO2 50% -PaO2 60 -PEEP = 5cm -PS = 10 -NIP -20 to -30 -Minute volume 10L/min -ABGs need to be normal for them How do you manage a patient with BP 100/52 and ICP 10? - ANSWER--notify the doctor -CPP = MAP - ICP = (100+52+52) =204 /3 = 68 - 10 = 58 -58 is too low (should be 70) What is the normal range for CPP? - ANSWER-70-100 mmHg What is the normal range for MAP? - ANSWER-65-100 mmHg What are the interventions for a patient during a seizure? - ANSWER--safety: pillow under head, padding side rails, moving furniture -oxygen and suction in the room -turn on side -describe the time, movement, post-ictal vital signs -administer medication What are the interventions for a patient post-seizure? - ANSWER--turn on side with HOB elevated -monitor vital signs -assess ABCDs What causes a seizure? - ANSWER-Abnormal electrical brain activity What are the manifestations of Parkinson's Disease? - ANSWER--bradykinesia -poor posture, postural instability-shuffling gait -tremors, pill rolling -rigidity -mask-like features What is the treatment for Parkinson's Disease? - ANSWER--meds: levodopa, carvedopa (good response for 1-2 years) How do we decrease ICP? - ANSWER--elevate HOB -keep head midline -spread out care -do not do hip flexions or anything in the abdomen What is the normal range for ICP? - ANSWER-5-15 mmHg Alan is a 17-year-old male who comes to the clinic with c/o feeling "bad," fatigue, constant thirst, and frequent urination. Focused assessment reveals rapid deep respirations (rate 28) with a fruity breath odor. A capillary blood glucose is 484 mg/dL. 1. What type of acid-base imbalance would you expect Alan to have? 2. What is causing it? 3. What type of compensation would you expect or not expect? Explain. 4. What will Alan's ABGs look like? 5. What is the treatment? - ANSWER-1. Metabolic acidosis 2. Breakdown of fats for energy secondary to lack of insulin and subsequent inability to utilize glucose for energy. Ketones are an acid byproduct of fat breakdown. 3. The deep, rapid respiratory rate (Kussmaul respirations) demonstrate respiratory compensation—may be partial or full, depending on longevity of the hyperglycemia. 4. A diabetic ketoacidosis is a metabolic acidosis indicated by a pH 7.35 and a HCO3 22 mEq/L. The PCO2 will be within the normal range if the acidosis is uncompensated but will be 35 mm Hg if compensation has occurred. The PaO2 will not be affected usually. 5. Administration of insulin to promote normal glucose metabolism and administration of fluids and electrolytes to replace those lost because of the hyperglycemia. Anthony is a 54-year-old male with a history of nausea and vomiting for the past week. He has been self-medicating himself with baking soda to control his abdominal discomfort. 1. What type of acid-base imbalance would you expect Anthony to have? 2. What is causing it? 3. What type of compensation would you expect or not expect? Explain. 4. What will Anthony's ABGs look like? 5. What is the treatment? - ANSWER-1. Metabolic alkalosis 2. Loss of gastric acid and excess bicarbonate with baking soda ingestion 3. There is limited compensation for metabolic alkalosis. The kidneys can respond by increasing excretion of bicarbonate. The respiratory system can respond by decreasingrespirations, but once the carbon dioxide level increases, stimulation of chemoreceptors results in increased ventilation. 4. The metabolic alkalosis in this case would be reflected by a pH 7.45 and a HCO3 26 mEq/L. Because of the duration of this condition, compensation may be indicated by a PCO2 45 mm Hg. 5. Determine the underlying cause of the vomiting if possible, and stop the use of baking soda (sodium bicarbonate). Antiemetic drugs and nasogastric intubation may help relieve the vomiting, and IV replacement of fluids and electrolytes may be necessary. What are some examples of clinical manifestations of metabolic acidosis? - ANSWER-- headache -confusion -drowsiness -increased respiratory rate and depth -decreased blood pressure -decreased cardiac output -electrolyte imbalance (hyperkalemia or hypocalcemia) -dysrhythmias What are some examples of clinical manifestations of metabolic alkalosis? - ANSWER-- hypertonic muscles and cramping -reduced respiratory rate -tacycardia -symptoms of hypokalemia What are some examples of clinical manifestations of respiratory acidosis? - ANSWER-- hypotension -flushed skin -increased pulse, respiratory rate, and BP -mental changes -feeling of fullness in head What are some examples of clinical manifestations of respiratory alkalosis? - ANSWER- -lightheadedness -inability to concentrate -numbness and tingling -sometimes LOC Jessi is a 22-year-old female who has been on a 3-day party binge. Her friends bring her to the ED after being unable to awaken her. Assessment reveals shallow respirations with a rate of 8/min, diminished breath sounds, and decreased level of consciousness. 1. What type of acid-base imbalance would you expect Jessi to have? 2. What is causing it?3. What type of compensation would you expect or not expect? Explain. 4. What will Jessi's ABGs look like? 5. What is the treatment? - ANSWER-1. Respiratory acidosis 2. Hypoventilation secondary to alcohol ingestion 3. Compensation might be noted if the respiratory depression has been present for 24 hours or more: The HCO3 may be elevated as the result of renal compensation. If her respiratory depression has lasted less than 24 hours, there will not yet be any renal compensation. 4. Respiratory acidosis reflected by pH 7.35 and PCO2 45 mm Hg. The HCO3 will be normal (20-30 mEq/L) if her respiratory depression has lasted less than 24 hours; if longer than 24 hours, the HCO3 may be elevated as the result of compensation. The PaO2 may be 80 mm Hg because of respiratory depression leading to hypoxemia. 5. Determine the cause of the respiratory depression. If induced by opioids or benzodiazepines, treat with appropriate antagonists. If induced by alcohol or other CNS depressants, breathing must be stimulated until the effects of drugs have worn off. Mechanical ventilation may be necessary to increase respiratory rate and depth, increasing oxygenation and promoting excretion of carbon dioxide. Kellie is an 18-year-old female who presents to the ED after a sexual assault. She is hysterical and in severe emotional distress. Her blood pressure is 140/96, heart rate 104, respiratory rate 38, and oxygen saturation 98%. Lung sounds are clear. 1. What type of acid-base imbalance would you expect Kellie to have? 2. What is causing it? 3. What type of compensation would you expect or not expect? Explain. 4. What will Kellie's ABGs look like? 5. What is the treatment? - ANSWER-1. Respiratory alkalosis 2. Hyperventilation secondary to anxiety and hysteria 3. None at this point—compensation would not be occurring yet in this acute event. However, buffering of acute respiratory alkalosis may occur with shifting of bicarbonate (HCO3-) into cells in exchange for Cl-. It would take several days for renal compensation to occur. 4. Respiratory alkalosis indicated by pH 7.45 and PCO2 35 mm Hg. The HCO3 will be normal (22-26 mEq/L) because compensation will not occur in this acute event. 5. Relieve her anxiety possibly with medication such as benzodiazepines, stay with her and coax her to take slower breaths. You may have her breathe into a paper bag placed over her nose and mouth so she rebreathes CO2. True/False: The earliest sign of increasing ICP is a change in LOC. - ANSWER-True