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Monitoring in the Intensive Care Unit

Todd Costantini, MD, FACS

Professor of Surgery

Chief, Division of Critical Care and Acute Care Surgery

Interim Director, Translational Center for Resuscitative Trauma Care

January 8, 2026

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Acute Care Surgery Is…

Emergency General Surgery

Trauma

Surgical Critical Care

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These Patients are Sick

Scott et al. JAMA Surg 2016;151:e160480.

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Acute Care Surgery Fellowship

  • Two-year program offers fellows broad training in trauma and emergency general surgery (and elective general surgery)
  • It provides a non-ACGME accredited second year of training in addition to the ACGME accredited Surgical Critical Care fellowship
  • Fellows spend approximately 6 months on the Emergency General Surgery service functioning as a junior attending
  • Focused rotations to provide relevant operative experience
    • Vascular
    • Hepatobiliary / Transplant
    • Thoracic Surgery

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What is the public’s expectation when they are really sick….

  • To receive optimal and timely care in their hospital of choice
  • If trauma, they expect to be treated at a trauma center…
  • If they have an emergency surgical problem, they expect to be treated effectively and efficiently by a specialized surgeon
  • If they need ICU care, they expect to be admitted to an ICU with a competent team of intensivists, in their disease process.

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Monitoring in the ICU: Outline

  • Who works in the ICU?
  • Why do we put people in ICU?
  • “Gold standard” monitors
  • “Less” invasive and noninvasive techniques

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US Critical Care Training Pathways

  • Surgical
  • Anesthesiology
  • Medicine
  • Pulmonary Medicine
  • Cardiology/Cardiac Surgery
  • Emergency Medicine
  • Neurology/Neurosurgery
  • OB/GYN

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The presence of surgeons in intensive care units

provides specific insights and perspectives to the care

of surgical patients sometimes not fully appreciated

by the nonsurgical practitioners caring for the

same patients. 

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The Intensivist Model

  • Dedicated ICU responsibility
  • Available to see patients thru the day
  • Multi-professional team approach, low hierarchy
  • Extended hours and quick availability
  • Data-driven process and outcomes work
  • Comfortable with protocols

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The Patient is Here!

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Intensive Care is deployed in multiple settings

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Common ICU Equipment

  • Mechanical ventilator
  • Monitors
  • Dialysis
  • Drugs/Drips
  • Care Team
    • Intensivists
    • Nurses
    • Pharmacists
    • Respiratory therapists
    • Social workers
    • Nutritionists
    • Lots of others

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Monitoring in the ICU

  • How difficult is it to get the clinical data?

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  • Do I believe the information?

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  • What can I do with the information?
    • Will it change clinical decision making?

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What are the clinical questions?

  • What is the volume status?
  • What is the volume status?
  • What is the volume status?

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  • Is cardiac function normal?

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What can you monitor?

  • Hemodynamics- arterial blood pressure, cardiac parameters
  • Brain function- EEG, ceribel
  • All sorts of biochemical parameters (Glucose, lactate, clotting cascade, others)
  • Perfusion of specific organs
  • Vital signs- urine output, temperature, HR, oxygenation, etc

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Monitoring Endpoints Not Showing Consistent Benefit

  • Continuous EKG monitoring
  • Pulse oximetry
  • Pulmonary artery catheters
  • ICP monitoring

But can all have their place in ICU care

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Pulse Oximetry

  • “The conflicting subjective and objective results of the studies, despite an intense, methodical collection of data from a relatively large population (>20K patients!), indicates that the value of perioperative monitoring with pulse oximetry is questionable in relation to improved reliable outcomes, effectiveness and efficiency.”

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Pedersen, et al, Cochrane Database Syst Rev 2001

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…no monitoring device, simple or complex, will change the outcome if an effective treatment of the primary disease is not available or is initiated too late.

P.G. Berthelsen, Acta Anesthesiol Scanda 2006

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Reasons for Invasive Monitoring

  • Diagnosis of shock
  • Assess intravascular volume
  • Guide vasoactive therapy
  • Monitor end organ perfusion

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An exact science is dominated by the idea of approximation.

Bertrand Russell

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Invasive Monitoring Mainstays in the ICU

VARIOUS NON-INVASIVE MONITORS

ARTERIAL LINE MONITORING

CVP MONITORING

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Ultrasound Guided Central Line Placement

Saugel et al. Critical Care. 2017;21:225

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Cardiac Output

Heart Rate

Rhythm

Preload

Afterload

Contractility

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Preload

Cardiac Function

Peripheral microcirculation

What Do We Want to Measure?

End Organ Perfusion

Cellular Function

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Central venous pressure monitoring: Goldilocks theory

CVP low= Blood volume low

CVP high= Blood volume high

Right?

CVP=Fillling status of the right ventricle

Really?

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Relationship of blood volume to CVP

Baek et al. Surgery 1975;78:304

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Relationship of blood volume to CVP

Shippy et al. CCM 1984; 12:107

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Fluid Resuscitation in Septic Shock – VASST Trial

Russell, et al, N Engl J Med. 2008

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Lancet. 2005;366:472-77.

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Copyright © 2012 American Medical Association. All rights reserved.

Date of download: mm/dd/yyyy

From: National Trends in Use and Outcomes of Pulmonary Artery Catheters Among Medicare Beneficiaries, 1999-2013

JAMA Cardiol. 2017;2(8):908-913. doi:10.1001/jamacardio.2017.1670

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Rivers et al, N Engl J Med. 2001:345:

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Rivers et al, N Engl J Med. 2001:345:

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Cardiac Hemodynamics

  • Pulse Wave Analysis

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  • Pulse pressure variation

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Saugel, Br J Anesth, 2021

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Pulse Pressure Variation

  • Normal: arterial pulse pressure falls during inspiration, rises during expiration due to changes in intrathoracic pressure

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  • In ventilated patients: this pattern reverses

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  • Accentuated in setting of intravascular volume deficiency

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  • Therefore PPV: a measure of preload responsiveness

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Teboul, AJRCCM, 2019

Spontaneous breathing

False +

Cardiac arrhythmias

False +

Low Vt

False −

Low lung compliance

False −

Increased intraabdominal pressure

False +

Very high respiratory rate (HR/RR < 3.6)

False −

Right ventricular dysfunction

False +

Conditions Where Pulse Pressure Variation Is Less Reliable

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Imaging Techniques: Cardiac Function

  • Ultrasound/Echo

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  • Esophageal/transthoracic

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  • Increasingly portable

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POCUS- Point of Care US

  • Not a formal Echo!
  • Questions:
    • Fluid around the heart/lungs
    • How is the heart contracting? (global function only)
    • IVC variability with respiration (intravascular volume status)
  • Shortcomings: Not continuous, requires interpretation

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IVC Diameter

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J Trauma Acute Care Surg. 2020;88:70

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E-FAST Exam

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47 │

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Thoracic Ultrasound

Normal

Pneumothorax

Seashore Sign

Barcode Sign

Lung Sliding

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NPJ Digital Medicine. 2024;14

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Conclusions

  • Mainstays of ICU Monitoring: Arterial and Central Venous Catheters
  • Newer monitors: Allow noninvasive measurement of clinically-significant variables in the ICU:
    • Hemodynamics
    • Sedation
    • Pupillometry
  • New innovations in technology will allow for the deployment of non-invasive, continuous hemodynamic monitoring

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Todd Costantini, MD, FACS

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Division of Critical Care and Acute Care Surgery

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cost0086@umn.edu

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Lord, et al. Lancet. 2014;384:1455-1465

Critical Care &

Acute Care Surgery