The Physiologically Difficult Airway

Jarrod M. Mosier, MD , Raj Joshi, MD , Cameron Hypes, MD, Garrett Pacheco MD, Terrence Valenzuela, MD, John Sakles MD.
                                      University of Arizona ICU and ED Departments.
                                   Published, Western Journal of Emergency Medicine 2015

Full text available via open access http: escholarship.org/uc/uciem_westjem 

DOI 10.5811/westjem/ 2015

With recognition that many tools ( DL, VL, FOB, Surgical neck access),  are now available for the placement of endotracheal tubes and that CPAP , BIPAP also make a powerful contribution to oxygenation and ventilation ,  there remains another dimension of the airway management problem that needs to be addressed. 

Physiological Factors:

This important contribution to the teaching of Airway strategy underlines the four physiological states that add a complexity and risk to the Difficult Airway patient management. The special problems in the ICU and the ED are often coloured by the complex physiology of people who are suffering from profound general disorders. It is therefore fitting that this new look at the difficult Airway should come from Mosier (ICU) and Sakles (ED). Separation of these factors for special education and acute care consideration will surely make care safer in critical care areas.

1. Hypoxemia - with a patient at an unfavourable point on the oxygen dissociation curve leaving reduced margin for rapid deterioration. The pre oxygenation process becomes important prior to attempts at intubation. The use of Nasal approaches to provision of procedural oxygen are currently attracting more attention and study. These include the Thrive Hi Flo Nasal oxygen strategy, the simple use of nasal prongs (less effective but still added value) and nasal TSE PAP which uses the nose as a conduit for CPAP with a modified #2 Childrens mask.

    2. Hypotension- addressed  with standard volume optimization support  and pressor use as indicated. 

    3. Severe Metabolic acidosis - treated with disease specific therapy (i.e. Diabetic Keto-acidosis) and or other cause specific therapy such as septic state therapy.

    4. Right Ventricular failure - firstly awareness of the diagnosis is key followed by excellent strategies defined by truly expert care. The following are considered to be of value by Mosier and his team 1. Available bedside cardiac echo to assess right heart reserve allowing fluid use, 2. pre oxygenation (see above) 3. consider etomidate induction, 4. consider Norepinephrine to increase systemic pressure, and low mean airway pressure ventilation. To obtain a discussion of these outline points consult the original detail embodied in the paper itself.

Abstract

Video Laryngoscopy Improves Odds of First Attempt Success at Intubation in the ICU: A Propensity-Matched Analysis

Cameron D Hypes, Uwe Stolz, John C Sakles, Raj R Joshi, Bhupinder Natt, Josh Malo, John W Bloom, and Jarrod M Mosier

Jarrod Mosier and John Sakles continue to be among leaders in clinical evaluation of airway management in ICU and ED areas. This article reinforces the growing understanding that in ICU , where most caregivers are no longer from an anesthesiology training base but from various other disciplines, the Video Laryngoscope is easier to learn and use. The skill retention is also superior using VL so overall performance for first pass success is superior to DL.
The Abstract for ICU application is as follows:

Abstract

 Rationale: Urgent tracheal intubation is performed frequently in intensive care units and incurs higher risk than when intubation is performed under more controlled circumstances. Video laryngoscopy may improve the chances of successful tracheal intubation on the first attempt; however existing comparative data on outcomes are limited. 

Objectives: To compare first attempt success and complication rates during intubation when using video laryngoscopy compared to traditional direct laryngoscopy in a tertiary academic medical intensive care unit. Methods: We prospectively collected and analyzed data from a continuous quality improvement database of all intubations in one medical intensive care unit between January 1st, 2012 and December 31st 2014. Propensity-matching and multivariable logistic regression were used to reduce the risk of bias and control for confounding.

 Measurements and Main Results: A total of 885 intubations took place over the study period. Of these, 673 (83.2%) were performed using video laryngoscopy and 

136 (16.8%) using direct laryngoscopy. 

First attempt success with video laryngoscopy was 80.4% (95% CI 77.2 to 83.3%) compared and 65.4% (95% CI: 56.8 to 73.4%) for intubations performed with direct laryngoscopy, p=<0.001. In a propensity-matched analysis, the odds ratio for first attempt success with video laryngoscopy vs. direct laryngoscopy was 2.81 (95% CI 2.27 to 3.59). The rate of arterial oxygen saturation events during the first intubation attempt was significantly lower for video laryngoscopy than for direct laryngoscopy (18.3% vs. 25.9%, p=0.04). The rate of esophageal intubation during any attempt was also significantly lower for video laryngoscopy (2.1% vs. 6.6%, p=0.008). 

Conclusions: Video laryngoscopy was associated with significantly improved odds of first attempt success at tracheal intubation by non-anesthesiologists in a medical intensive care unit. Esophageal intubation and oxygen desaturation complicating intubation occurred less frequently with the use of video laryngoscopy. Randomized clinical trials are needed to confirm these findings.

Read More: http://www.atsjournals.org/doi/abs/10.1513/AnnalsATS.201508-505OC#.VniHCTa0GfM   

   

Ventrain- A novel approach to ventilation through small bore cannulas by Professor Dietmar Enk

The Ventrain device is designed to take advantage of the Bernoulli Principle to 

create a control that will use the pressure of an Oxygen source to create 

positive pressure inflow and when the appropriate orifice is blocked a negative pressure for expiration is created by the passage of air over the entrance to the endotracheal tube. This is explained in the Text.

This substantially improves the potential to ventilate through small caliber cannulas. 

The simplicity and brilliance of the design suggests an important role that will improve difficult airway management and also possibly a number of other situations.