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 A ventilator is a machine that delivers a flow of gas for a certain amount of time by increasing proximal  airway pressure, a process which  culminates in a delivered tidal volume. Because of the imprecise, inconsistent, and outdated terminology used to describe modern ventilators, many clinicians often misunderstand exactly how a ventilator functions. Understanding the exact instructions that a ventilator follows to deliver a breath for the various modes of ventilation is crucial for optimal ventilator management. Anatomy of  a  Breath Breathing is a periodic event, composed of repeated cycles of inspiration and expiration. Each breath, defined as one cycle of inspiration followed by expiration, can be broken down into four components, known as phase variables. These phase variables determine when inspiration begins (trigger), how flow is delivered during inspiration (target), when inspiration ends (cycle), and proximal airway press...

 Understanding mechanical ventilation must start with a review of the physiology and mechanics of normal spontaneous breathing. Spontaneous breathing is defined as movement of air into and out of the lungs as a result of work done by an individual’s respiratory muscles. Positive pressure ventilation, on the other hand, is defined as movement of air into the lungs by the application of positive pressure to the airway through an endotracheal tube, tracheostomy tube, or noninvasive mask. Lung Volume The lungs sit inside a chest cavity surrounded by the chest wall. The potential space between the lungs and the chest wall is known as the pleural space. The lungs, composed of elastic tissue, have a tendency to recoil inward, and the chest wall has a tendency to spring outward. If the lungs were removed from the chest cavity and were no longer being influenced by the chest wall or the pleural space, they would collapse like a deflated balloon. Similarly, remo...

 Wound Closure Technique: Overview, Indications, Contraindications Share Overview Wound closure techniques have evolved from the earliest development of suturing materials to comprise resources that include synthetic sutures, absorbables, staples, tapes, and adhesive compounds. The engineering of sutures in synthetic material along with standardization of traditional materials (eg, catgut, silk) has made for superior aesthetic results. Similarly, the creation of topical skin adhesives (the monomer 2-octyl cyanoacrylate), surgical staples, and tapes to substitute for sutures has supplemented the armamentarium of wound closure techniques. Aesthetic closure of a wound, whether traumatic or surgically induced, is based on knowledge of healing mechanisms and skin anatomy (see the image below), as well as an appreciation of suture material and closure technique. Choosing the proper materials and wound closure technique ensures optimal healing. [1] Anatomy of the skin.  Anatomy of th...

 Intravenous Insulin Therapy: Practice Essentials, Overview, Key Components of Insulin Protocols Practice Essentials Hyperglycemia often complicates the clinical course of critically ill patients in the intensive care unit (ICU). Intravenous insulin infusions can control hyperglycemia more efficiently than intermittent subcutaneous insulin therapy and may be the preferred approach in certain settings, such as postcardiac surgery. Many intravenous insulin protocols have been developed, such as the Georgia Hospital Association Protocol and the Portland Protocol. [1] Indications for intravenous insulin Because of their susceptibility to deep wound infections, patients who undergo open cardiac surgery may benefit from the routine use of intravenous insulin. Patients with diabetes who have suboptimal glucose control with conventional subcutaneous insulin treatment may also benefit from intravenous therapy. Target blood glucose levels The optimal range of glucose control in critically il...