Measuring exhaled carbon dioxide (End Tidal CO2, ETCO2) is an important ICU technology that can used to confirm ETT placement, to ensure safer procedural sedation, to guide ACLS/resuscitation, and to monitor cardiac and pulmonary physiology in realtime. This ICU OnePager describes the physiology, equipment, waveforms you will see with ETCO2 monitoring.

We use pulse oximetry on every patient every day in the ICU, but how does this machine actually work and, importantly, how does it fail? This ICU #OnePager reviews the principle of pulse oximetry and the many factors that can cause inaccurate readings: darker skin pigmentation, nail polish, low flow states (ECMO & LVADs), and abnormal hemoglobins (MetHB, COHb, etc). It introduces the important concept of pulse ox lag-time and also shows how the waveform can provide useful physiologic clues about vascular tone/compliance.

Non-invasive positive pressure ventilation (NIPPV) is a valuable technique to support oxygenation and ventilation in people with respiratory failure to potentially avoid intubation. This #OnePager reviews when to (and when not to) use NIPPV, as well as modes  (CPAP, BiPAP/BiLevel, & AVAPS) and interfaces (nasal, partial face, full face, & helmet).

External cardiac pacing is a technique for temporarily treating brady- and tachydysryhthmias in the ICU. This #OnePager covers the basics, including types of pacing leads (transvenous vs epicardial, bipolar vs unipolar), pacing modes (VVI, DDD, etc), and a stepwise guide to initiating pacing.

Occasionally medical and interventional therapies can’t stop an upper GI bleeds due to esophageal varices. In those rare cases, placement of a Minnesota Tube can be life-saving. This #OnePager reviews how Minnesota Tubes work & shows you how to safely place and secure them. There are also some great how-to videos that walk you through the process step by step.

Renal replacement therapies are commonly used in the ICU to remove excess fluid and clear the blood of endogenous and exogenous toxins. This ICU OnePager explains the physics & physiology of dialysis, discussing the key concepts (dialysis = diffusion, hemofiltration/ultrafiltration = convection) and the components of the dialysis circuit (pumps, dialyzer, dialysis solution, replacement fluid, etc). It also reviews all the confusing modes of dialysis:  IHD, SLED, and CRRT including SCUF, CVVHF, CVVHD, and CVVHDF.

Understanding Hypoxemia (low oxygen in the blood) & hypoxia (low oxygen in the tissues) is a fundamental part of critical care. This OnePager reviews all the key concepts (oxygen content & delivery, Aa gradient) and explains all FIVE causes of hypoxemia (low inspired O2, alveolar hypoventilation, V/Q mismatch, right to left shunt, and diffusion limitation) plus a bonus SIXTH cause which is often overlooked (low mixed venous O2).

Massive hemoptysis is both terrifying and a true emergency. This ICU #OnePager reviews the d/dx (BATTLECAMP) and walks through an approach for workup, airway management, and interventions (bronchoscopic, IR, and surgical) to control hemorrhage.

Extracorporeal Membrane Oxygenation (ECMO) is the most advanced life support modality available in the ICU, able to provide oxygenation and CO2 removal (VV ECMO) as well as support cardiac output (VA ECMO). This OnePager is the first in a series about ECMO, that orients you to the basic ECMO circuit & reviews the basics of ECMO terminology, equipment, and physiology.

Lactate and Lactic acid are frequently used (& oft misunderstood) labs in the ICU. This OnePager reviews the physiology of why/how we produce lactic acid and breaks lactic acidosis into two categories: Impaired O2 Delivery (Type A Lactic Acidosis) and Impaired O2 clearance/utilization (Type B Lactic Acidosis). I also discuss the rare and easily missed Type D Lactic acidosis (due to bacterial production of the stereoisomer).

Many conditions can raise intra-abdominal pressure, potentially leading a life-threatening complication: abdominal compartment syndrome (ACS). This #OnePager reviews the physiology of Abdominal Perfusion Pressure and ACS, shows you how to approximate IAP using bladder pressure measurement, and discusses an approach to diagnosis & approach to management.

In this second installment of the ECMO OnePager series, we review basic common troubleshooting for VV ECMO. Issues range from expected complications requiring monitoring (e.g. rising transmembrane pressure) to immediately life threatening emergencies that require urgent action (air embolism, oxygenator failure, etc). Understanding what can go wrong, and how emergent any of these issues are, is critical in managing people on ECMO.