Study guide
5.1 Hemodynamic Monitoring
ABIM Neurocritical Care Subspecialty Certification Exam
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1 Introduction & Exam Overview
1.1 Current Exam Facts 1.2 Eligibility, Practice Pathway, and the IM Training Route 1.3 Format, Scoring, Pearson VUE, and Score Reports 1.4 How to Use This Independent Study Guide
2 ICU Neurologic Exam, Cerebral Physiology, and CSF
2.1 Neurological Examination in the ICU 2.2 Cerebral Physiology, ICP, CBF, and Autoregulation 2.3 CSF Physiology
3 Core Neuropharmacology
3.1 Osmotic Agents 3.2 Anti-Seizure Drugs 3.3 Anesthetics, Sedatives, Analgesia, and Paralytics 3.4 Antihypertensives, Vasopressors, and Inotropes
4 Reperfusion Drugs, Airway, and Ventilation
4.1 Thrombolytics, Anticoagulants, and Antiplatelets 4.2 Reversal of Anticoagulation After Acute Hemorrhage 4.3 Airway Management and Tracheostomy 4.4 Mechanical Ventilation
5 Hemodynamics and Shock
5.1 Hemodynamic Monitoring 5.2 IABP, Temporary VADs, LVAD, and ECMO 5.3 Diagnosis and Management of Shock
6 Nutrition, Temperature, and ICU Prophylaxis
6.1 Nutrition (01.J) 6.2 Temperature Control (01.K) 6.3 ICU Prophylaxis, Delirium, and Early Mobility (01.L)
7 General Trauma
7.1 Emergency Evaluation of Polytrauma, Chest, and Abdominal Trauma 7.2 Long-Bone Fractures and Fat Embolism 7.3 Burns, Electrical Injury, and Hanging/Strangulation
8 Pulmonary Critical Care
8.1 Pulmonary Physiology and ARDS (01.N.1–2) 8.2 PE, Pneumonia, and Pulmonary Edema (01.N.3, 7–8) 8.3 COPD, Asthma, PAH, and Bronchoscopy Basics (01.N.4–6, 9)
9 Cardiovascular Critical Care
9.1 Cardiovascular Physiology, Stress Cardiomyopathy, ACS, and Valves 9.2 Arrhythmias and Pacing 9.3 Acute Aortic Dissection and Cardiac Ultrasound
10 Renal and Infectious Disease
10.1 AKI, RRT, and Renal Drug Dosing 10.2 Acid-Base and Electrolyte Disorders 10.3 Severe Sepsis, Septic Shock, and Infective Endocarditis 10.4 Antimicrobial Use and Infection in the Immunosuppressed
11 Endocrine and Salt-Water Disorders
11.1 Pituitary Apoplexy, DI, and Panhypopituitarism (01.R.1–4) 11.2 SIADH and Cerebral Salt Wasting (01.R.5–6) 11.3 Thyrotoxicosis, Myxedema, Adrenal Crisis, and Dysglycemia (01.R.7–9)
12 Gastrointestinal Critical Care
12.1 GI Physiology, Acute Abdomen, Bleed, Ileus, and Perforation (01.S.1–5) 12.2 Mesenteric Ischemia and Abdominal Compartment Syndrome (01.S.6–7) 12.3 Fulminant Liver Failure, Cirrhosis Decompensation, and Hepatic Dosing (01.S.8–10)
13 Hematologic Disorders
13.1 Anemia, Transfusion, Thrombocytopenia, Coagulopathy, and DIC (01.T.1–4) 13.2 VTE in the Neuro ICU (01.T.5) 13.3 Chemo/Immune, SCT, CAR-T, Sickle Cell, and TMA (01.T.6–10)
14 Neuroimaging
14.1 CT of Brain and Spine 14.2 MRI and CT/MR Perfusion 14.3 Noninvasive Angiography and Catheter Angiography
15 EEG, EMG, and CSF Analysis
15.1 EEG, Standard and Processed (02.B) 15.2 Basic EMG Interpretation (02.G) 15.3 CSF Analysis (02.H)
16 ICP, TCD, and Multimodality Monitoring
16.1 ICP Monitoring (02.C) 16.2 Transcranial Doppler (02.D) 16.3 Brain-Tissue Oxygen and Multimodality Monitoring (02.E–F)
17 Brain Death and Bedside Procedures
17.1 Brain Death Prerequisites and Clinical Exam (02.I) 17.2 Apnea Testing and Ancillary Studies (02.I) 17.3 Vascular Access, Thoracic Echo, and Lung Ultrasound (02.J–L)
18 Coma, Anoxia, and Intracranial Hypertension
18.1 Coma and Other States of Altered Consciousness (03.A) 18.2 Global Anoxia-Ischemia and Post-Resuscitation Encephalopathy (03.A.1) 18.3 Toxidromes, ICU Delirium, and Hypertensive Encephalopathy (03.A.2–4) 18.4 Intracranial Hypertension as a Disease State (03.B)
19 Acute Ischemic Stroke
19.1 IV Reperfusion Therapy (03.C.3) 19.2 Mechanical Thrombectomy Windows and Imaging Selection (03.C.3) 19.3 Malignant Hemispheric Infarction and Basilar Artery Occlusion (03.C.1–2)
20 Intraparenchymal Hemorrhage
20.1 Intracerebral Hematoma (03.D.1) 20.2 Cerebellar Hematoma (03.D.2) 20.3 Intraventricular Hemorrhage (03.D.3)
21 SAH, CVST, and Spinal Cord Infarction
21.1 Aneurysmal Subarachnoid Hemorrhage (03.E.1) 21.2 Non-Aneurysmal SAH (03.E.2) 21.3 Cerebral Venous Sinus Thrombosis (03.F) 21.4 Spinal Cord Infarction (03.G)
22 Vascular Anomalies and Traumatic Brain Injury
22.1 Unruptured Aneurysm, Cavernoma, AVM, and Dural AVF (03.H) 22.2 Diffuse Axonal Injury and Cerebral Contusions (03.I.1–2) 22.3 Epidural Hematoma, Subdural Hematoma, and Penetrating Injury (03.I.3–4, 7) 22.4 Arterial Dissection and Carotid-Cavernous Fistula (03.I.5–6)
23 Spine, Hydrocephalus, and CNS Infection
23.1 Spinal Cord Injury, Central Cord, and Neurogenic Shock (03.J) 23.2 Unstable Spine Fractures (03.K) 23.3 Hydrocephalus and CSF Diversion (03.L) 23.4 Acute CNS Infections (03.M)
24 Seizures and Neuromuscular Emergencies
24.1 Status Epilepticus and Seizures (03.N) 24.2 Guillain-Barré Syndrome (03.O.1) 24.3 Myasthenic Crisis (03.O.2) 24.4 Motor Neuron Disease, Acute Myopathies, Rhabdomyolysis, and CINM (03.O.3–6)
25 Inflammatory Disease, Neuro-Oncology, and Special Populations
25.1 Fulminant Demyelinating Diseases (03.P) 25.2 Autoimmune Encephalitis and Acute Autonomic Hyperactivity (03.Q–R) 25.3 Neuro-Oncology and Treatment Complications (03.S) 25.4 Pregnancy/Post-Partum, Post-Transplant, and Pediatric Patients (03.T–U)
26 Neurosurgical and Perioperative Complications
26.1 Postoperative Seizures, Hemorrhage, Ischemia, and Hyperperfusion (04.A, C, D, H) 26.2 Infection, CSF Leak, and Pneumocephalus (04.B, E, F) 26.3 Complications of EVD and Lumbar Drain (04.G, I)
27 Ethics, Prognostication, and Organ Donation
27.1 Communication, Decision-Makers, Advance Directives, and DNR (05.A, B, G) 27.2 Uncertainties of Prognostication and the Self-Fulfilling Prophecy (05.C) 27.3 Palliative Care, Withdrawal, Withholding, and Futility (05.D–F) 27.4 Donation After Cardiac Death and Care of the Organ Donor (05.H–I)
5.1 Hemodynamic Monitoring
Key Takeaways Explain This Topic AI
Cerebral perfusion pressure equals mean arterial pressure minus intracranial pressure (or right atrial pressure if that value is higher); the Brain Trauma Foundation 4th edition targets CPP 60–70 mm Hg after severe TBI and treats ICP above 22 mm Hg.
Static central venous pressure does not reliably predict fluid responsiveness; high CVP can reflect right-heart failure, tamponade, high PEEP, or abdominal hypertension rather than adequate preload.
An arterial catheter supplies beat-to-beat MAP for CPP calculations; a pulmonary artery catheter and mixed venous oxygen saturation help when shock physiology is mixed or echocardiography cannot explain the picture.
Serial lactate, central venous oxygen saturation, and bedside ultrasound of the IVC and left ventricle are complementary tools, not replacements for a clinical perfusion exam.
After acute spinal cord injury, many centers still target MAP at least 85 mm Hg for up to 7 days; after aneurysmal SAH, keep euvolemia and raise blood pressure for symptomatic delayed cerebral ischemia rather than using prophylactic triple-H therapy.
Last updated: September 2026
Why monitoring is a perfusion problem
Quick answer: In the neuro ICU, mean arterial pressure (MAP) is useful only after you convert it into cerebral perfusion pressure (CPP) . CPP = MAP − ICP (use right atrial pressure instead of ICP if RAP is higher). The Brain Trauma Foundation 4th edition recommends treating intracranial pressure above 22 mm Hg and targeting CPP 60–70 mm Hg after severe traumatic brain injury (TBI); aggressively driving CPP above 70 mm Hg with fluids and vasopressors can increase adult respiratory-failure risk.
A cuff systolic pressure of 110 mm Hg can be adequate, inadequate, or excessive depending on whether the brain is swollen, the cord is ischemic, or the patient is in septic shock with a normal intracranial vault. The ABIM/ABPN neurocritical care exam tests whether you can pick a tool that answers a specific physiologic question and then apply a disease-specific target, not whether you can recite a device brand name.
MAP is the time-averaged arterial pressure and the usual numerator for brain and spinal cord perfusion. CPP is the pressure gradient driving cerebral blood flow. When ICP is 25 mm Hg and MAP is 80 mm Hg, CPP is 55 mm Hg—below the TBI range—even though a medical ICU MAP of 80 mm Hg would look comfortable. Raising MAP with norepinephrine, lowering ICP with osmotherapy or cerebrospinal fluid drainage, or both, can restore CPP; treating the MAP number in isolation cannot.
Arterial catheter: the neuro-ICU workhorse
An invasive arterial line gives continuous MAP, easy arterial blood gases, and a waveform you can inspect for overdamping (flattened, underestimates systolic) or underdamping (overshoot, overestimates systolic). MAP is more robust to damping than systolic pressure and is the number you should use for CPP. Radial arterial catheters are first-line in most adults; femoral access is reasonable when radial arteries are vasoconstricted or when you need a proximal sampling site during peripheral venoarterial extracorporeal membrane oxygenation (VA-ECMO) (see Section 5.2 for Harlequin physiology). Place the transducer at the phlebostatic axis (mid-axillary line, fourth intercostal space) unless your unit has a validated protocol to level at the tragus for CPP—whatever you choose, keep MAP and ICP referenced consistently so the subtraction is physiologically meaningful.
Arterial lines do not measure cardiac output. They do let you calculate pulse pressure variation (PPV) as a dynamic marker of fluid responsiveness, but only when the patient is fully adapted to the ventilator, tidal volume is about 8 mL/kg predicted body weight, there is no arrhythmia, and the chest is closed. Lung-protective tidal volumes common after TBI and acute respiratory distress syndrome make PPV less reliable; do not give a fluid bolus just because PPV is 13% on 6 mL/kg ventilation.
Central venous pressure: what it is and what it is not
A central venous catheter in the superior vena cava estimates right atrial pressure (CVP) . CVP is useful as a right-sided filling pressure, as a trend after a fluid challenge, and as the downstream pressure for abdominal-organ perfusion when it exceeds ICP. It is a poor static predictor of whether stroke volume will rise after volume. A CVP of 12 mm Hg can mean adequate preload, right ventricular (RV) failure, pulmonary embolism, tamponade, high positive end-expiratory pressure, or abdominal compartment syndrome. Targeting a fixed CVP (the old 8–12 mm Hg early-goal-directed therapy number) is not a contemporary resuscitation endpoint.
If you need a volume-responsiveness answer, use a passive leg raise or a small, timed fluid challenge with a cardiac-output or velocity-time-integral (VTI) measurement, not a single CVP snapshot.
Pulmonary artery catheter and mixed venous saturation
A pulmonary artery catheter (PAC) remains useful when echocardiography and the clinical exam cannot sort mixed shock, when you need mixed venous oxygen saturation (SvO2) from the pulmonary artery, or when you are titrating support in severe RV failure or pulmonary hypertension. The PAC can report cardiac output (thermodilution), pulmonary artery pressures, pulmonary artery occlusion pressure as a left-atrial surrogate, systemic vascular resistance, and SvO2.
SvO2 reflects the balance of oxygen delivery and consumption. Values below about 65% suggest inadequate delivery (low cardiac output, anemia, hypoxemia) or high consumption, provided the sample is a true mixed venous specimen. PAC complications—arrhythmia, pulmonary-artery rupture, infarction, infection—mean you should not float a catheter for curiosity. Use it when the question is “is this cardiogenic, distributive, or both, and is oxygen delivery matching demand?”
Pulse-contour and minimally invasive cardiac output
Pulse-contour devices (calibrated transpulmonary thermodilution systems such as PiCCO, or uncalibrated arterial-waveform systems such as FloTrac) estimate stroke volume from the arterial waveform. Calibrated systems also yield global end-diastolic volume and extravascular lung water. They fail or mislead in severe aortic regurgitation, intra-aortic balloon counterpulsation, marked arrhythmia, and extreme vasoplegia. Treat them as trend monitors that still need an echocardiographic reality check when the numbers and the patient disagree.
Lactate, ScvO2, and ultrasound as non-invasive partners
Lactate is a tissue-perfusion marker. Serial clearance is more useful than a single value. It is not specific: seizures, liver failure, epinephrine infusions, thiamine deficiency, mesenteric ischemia, and β2-agonists all raise lactate without classic shock. In the neuro ICU, a lactate spike after a generalized convulsion is not, by itself, septic shock.
Central venous oxygen saturation (ScvO2) is sampled from a superior vena cava catheter. It is typically a few percentage points higher than SvO2 because it does not fully mix inferior vena cava and coronary-sinus blood. Historical early-goal-directed protocols targeted ScvO2 around 70%. After PROCESS, ARISE, and ProMISe, protocolized ScvO2-guided resuscitation is not required; a low ScvO2 still flags inadequate delivery when the clinical context fits.
Bedside ultrasound answers questions a PAC used to answer. Inferior vena cava (IVC) collapsibility in a spontaneously breathing patient (often >40–50%) suggests possible fluid responsiveness; IVC distensibility in a fully passive, ventilated patient (often >12–18%) does the same. IVC is unreliable with high PEEP, intra-abdominal hypertension, or RV failure. Look at the left ventricle: a hyperdynamic, underfilled cavity supports hypovolemia or vasoplegia; a dilated, hypokinetic ventricle supports cardiogenic shock. Right-ventricular dilation and septal flattening point toward obstructive physiology (pulmonary embolism, high ventilator pressures). Lung ultrasound B-lines support hydrostatic edema when you are deciding whether the next liter will help or harm.
Disease-specific MAP and CPP targets
Setting Usual hemodynamic question Common target (source / practice)
Severe TBI Is the brain being perfused without overshooting lungs? Treat ICP >22 mm Hg; CPP 60–70 mm Hg (Brain Trauma Foundation 4th edition). Avoid pushing CPP >70 mm Hg with fluids and pressors.
Acute traumatic spinal cord injury Is the cord being perfused after hypotension is corrected? Correct systolic hypotension <90 mm Hg promptly. Many centers still use MAP ≥85 mm Hg (often 85–90) for up to 7 days (AANS/CNS 2013, Level III). A 2024 AO Spine/Praxis-style update suggests a lower limit of 75–80 and an upper limit of 90–95 mm Hg for 3–7 days; evidence remains very low.
Aneurysmal subarachnoid hemorrhage, delayed cerebral ischemia Is symptomatic ischemia from low flow? Euvolemia for all. Raise blood pressure for symptomatic delayed cerebral ischemia (DCI) ; do not use prophylactic hypervolemia or prophylactic hemodynamic augmentation (AHA/ASA 2023). Unsecured aneurysms still need rerupture-risk judgment before aggressive hypertension.
Septic shock without intracranial hypertension Is a standard medical MAP enough? Initial MAP 65 mm Hg on vasopressors (Surviving Sepsis Campaign 2021). Raise the floor if CPP or spinal cord perfusion requires it.
Tools versus what they measure
Tool Primary measurements Best neuro-ICU use Main trap
Arterial catheter Beat-to-beat MAP, waveform, PPV, ABG CPP and SCI MAP titration Damped waveform; PPV invalid on low tidal volume or arrhythmia
CVP / RAP Right-atrial pressure Downstream pressure; trend after a challenge Static CVP ≠ volume responsiveness
PAC CO, SVR, PA pressures, occlusion pressure, SvO2 Mixed shock, RV failure, oxygen-delivery mismatch Pulmonary-artery injury; misread occlusion pressure
Pulse-contour CO Stroke volume, CO, sometimes lung water Trend CO during pressor wean AR, IABP, arrhythmia, extreme vasoplegia
Lactate Tissue hypoperfusion surrogate Serial clearance in shock Seizure, liver failure, epinephrine
ScvO2 SVC oxygen saturation Low value supports inadequate DO2 Not identical to SvO2; not a mandatory protocol target
Ultrasound (IVC, LV/RV, lung) Volume hints, ventricular function, edema First-line when PAC is not needed IVC fails in high PEEP, high abdomen, RV failure
The exam stem often gives you an arterial-line MAP, an ICP, and a CVP. Calculate CPP first. Then ask whether the next intervention should raise MAP, lower ICP, give volume, or add an inotrope—monitoring exists to make that choice, not to decorate the flowsheet.