Books:
A good anatomy and physiology text will save you a lifetime of pain.
Bullock & Hales - Principles of Pathophysiology
Guyton & Hall - Textbook of Medical Physiology
Intensive Care Books:
Cairo - Pilbeam's Mechanical Ventilation: Physiological and Clinical Applications - 6th Edition
Aitken, Marshall & Chaboyer - ACCCN's Critical Care Nursing - I used the 3rd Edition but understand there's a 4th Edition now.
ECG's
Dale Dubin - Rapid Interpretation of EKG's
Provides memorable and simple ways to help you understand and interpret ECG's
To practice, there's plenty of ECG libraries available on a variety of websites.
Web Resources:
Life in the Fast Lane - https://litfl.com/
A wealth of available resources across many areas with a strong focus towards emergency medicine and critical care.
EmCrit Blog - https://emcrit.org/
Another great site bringing a wealth of resources aimed at translating evidence based medicine into approachable bedside practices in the Emergency Department and Intensive Care Unit.
SMACC / CODA - https://codachange.org/
SMACC was the predecessor to CODA but they both offer fantastic podcasts and resources about all things critical care.
Pacing for Paramedics - https://prehospitalpacing.com/
Written by one of my former lecturers this website aims to help you better understand the behaviour of implanted cardiac devices.
Other:
Offering some valuable short courses and amalgamating many local and State based resources about Emergency Medicine, the paid courses are well worth the investment.
https://emergencyeducation.org.au/