Potassium (K + ) is the most abundant intracellular cation and is maintained within narrow physiologic limits. Although reported values vary, the normal serum K + level in humans typically ranges from 3.5 to 5.0 mEq Alterations in electrolyte concentrations…
Acid-base disorders Acid-base disorders can be quantified by using the physiologic, base-excess, and physiochemical approaches (Stewart method). The bicarbonate [HCO 3 − ] buffer system plays a central role in the physiologic and base-excess methods. They share nearly common explanations…
Oliguria is one of the most common problems faced by clinicians in the intensive care unit (ICU). The goal of this chapter is to understand the reasons for oliguria and provide an evidence-based, practical, physiology-based approach to diagnosing and treating…
Pathophysiology and classification The daily urine output is determined predominantly by the daily intake of fluids, daily solute excretion, and the urine-concentrating ability of the nephrons. The average person excretes about 600–800 mOsm of solutes per day, and average urine…
Epidemiology Pleural effusions are common in the intensive care unit (ICU). Estimated incidence depends on screening method and ranges from 8% by physical examination to 60% by ultrasound. , Transudative causes of effusion (heart failure, hypoalbuminemia) predominate in the medical…
Background and epidemiology of pulmonary edema Acute pulmonary edema is a commonly occurring emergency that demands immediate medical attention. , It is broadly classified into cardiogenic (increased hydrostatic pressure) or noncardiogenic (increased microvascular permeability) causes; however, it is common for…
Hyperbaric oxygen (HBO 2 ) treatment involves intermittent breathing of pure oxygen at greater than ambient pressure (>1.4 atmospheres absolute [ATA]). Over the past 20 years, HBO 2 has undergone refinement, with an increased understanding of the mechanisms of action…
Acute respiratory failure (ARF) is defined by the sudden onset of severe impairment of pulmonary gas exchange and is characterized by the inability of the lungs to meet the body’s metabolic needs for the transport of oxygen (O 2 )…
Normal cell function requires an adequate oxygen supply. Lack of oxygen at the cellular level is called hypoxia. Oxygen delivery (DO 2 ) to the tissues is determined by cardiac output and the arterial oxygen content, which in turn is…
The resting adult heart rate normally ranges from 60 to 100 beats per minute (bpm). Heart rate and rhythm abnormalities occur frequently in critically ill patients, and the incidence of sustained arrhythmias can approach 40% in some intensive care unit…