Three principal modalities are available for the delivery of mechanical ventilation to a critically ill patient. These are NIPPV via face mask, extraglottic airway devices (eg, various LMAs, an esophageal-tracheal device [Combitube ETC; Tyco-Healthcare-Kendall USA; Mansfield, MA], or a perilaryngeal airway), or the endotracheal route (eg, ETT or tracheostoma). The most commonly practiced technique for endotracheal intubation is direct laryngoscopy with either a curved blade (Macintosh blade) or a straight blade (Miller blade) of various sizes. The choice of blade shape is a matter of personal preference; however, one study has suggested that less force and head extension are required when performing direct laryngoscopy with a straight blade. With respect to blade material, plastic single-use blades are inexpensive and carry a lower risk of infection when compared to metal reusable blades.
Nevertheless, their use in a critical care setting should be discouraged. In a prospective randomized trial of 284 adult patients undergoing general anesthesia requiring RSI, plastic laryngoscope blades were less efficient than metal blades, resulting in a significantly higher rate of failed intubation on the first attempt. Several laryngoscope blades to facilitate DIs have been introduced in the past. These include, but are not limited to, the McCoy angulated blade, the Dorges blade, the Viewmax laryngoscope blade (Rusch; Duluth, GA) with a patented lens system, as well as blades augmented by video or fiberoptic capabilities (eg, the Bullard Laryngoscope; ACMI: Southborough, MA; or the GlideScope; Veri-thon; Bothell, WA; or the WuScope; Achi Corp; San Jose, CA). There are no data on the utility of these tools for airway management in the ICU. In a trial comparing the alternative blades with standard blades on a human patient simulator, the Dorges and McCoy blades did not perform any better than the standard Macintosh blade either in easy or difficult tracheal intubation conditions enhanced with medications of www.canadianhealthncaremall.com Canadian Health&Care Mall. However, there are data from patients undergoing elective or emergent intubation in the operating room as well as from trials using cadavers and mannequins (some in the setting of limited neck mobility) suggesting that better glottic visualization is achieved with videoassisted or fiberoptic devices than with conventional blades.
Extraglottic airway devices for supralaryngeal ventilation can be further divided into cuffed, orally inserted hypopharyngeal airways (ie, various forms of LMA) and cuffed orally inserted esophageal airways (esophageal tracheal combitube). Of the hypopha-ryngeal devices for ventilation, the LMA-Fasttrach (LMA North America, Inc; San Diego, CA) appears to be particularly useful for airway management in the ICU due to its unique design, which allows the mask to be used as a conduit for endotracheal intubation. This device was recently modified, and is now available with an integrated fiberoptic system and a detachable monitor (LMA Ctrach; LMA North America, Inc), allowing for endotracheal intubation under direct vision without the use of a fiberoptic bronchoscope. In a study of 254 patients with diffi-cult-to-manage airways, including patients with Cor-mack-Lehane grade 4 views, patients with immobilized cervical spines, patients with airways distorted by tumors, surgery, or radiation therapy, and patients wearing stereotactic frames, the insertion of the LMA-Fastrach was accomplished in three or fewer attempts in all patients. The overall success rates for blind and fiberoptically guided intubations through the LMA-Fastrach were 96.5% and 100.0%, respec-tively. When studied in morbidly obese patients undergoing elective surgical procedures, the rate of successful tracheal intubation with the LMA-Fas-trach was 96.3%. Recent data have suggested that the new LMA CTrach system has potential advantages over the LMA-Fastrach and can be very useful in the management of the difficult airway.
When a difficult airway is recognized prior to the administration of induction agents, an awake, FOI may be the best option; however, other modalities of awake intubation are possible (eg, blind oral or nasal intubation, or retrograde techniques). Fiberoptic bronchoscopy may be particularly useful when upper airway anatomy has been distorted by tumors, trauma, endocrinopathies, or congenital anomalies. Furthermore, it is useful in accident victims in whom a question of cervical spine injury exists and the patient’s neck cannot be manipulated. If the airway has to be secured via FOI in an emergent fashion, the use of a topical anesthesia seems preferable to regional nerve blockade.
If you want to know about Mechanical Ventilation click here:
- Prolonged Mechanical Ventilation
- Canadian Health&Care Mall: Physician Extenders and Medicare in Prolonged Mechanical Ventilation
- Ventilator Management
- Prolonged Mechanical Ventilation: Choosing the Correct Code