This page contains a Flash digital edition of a book.
gen concentration. It is a very useful formula in evaluating the degree of intrapulmonary shunt and subsequent compromise of cardiopul- monary function. The PaO2/FiO2 index is also valuable indicie of dif- fusion capability and a primary tool in assessing the degree of injury to the lung. Low diffusion states will have a low ratio of arterial oxygen in relation to a given FiO2. The PaO2/FiO2 index acts to identify the sever- ity of lung injury. If the PaO2/FiO2 index is < 300 strongly suspect Acute Lung Injury. (ALI) If the PaO2/FiO2 index is < 200 strongly suspect Acute Respiratory Distress Syndrome. (ARDS) The PaO2/FiO2 Ratio quantifies the ratio of oxygen available vs.


arterial oxygen required. Is an excellent predictor of mortality and is an essential tool in assessing lung injury. Ventilator Induced Lung Injury, (VILI), is a spectrum of lung injury


facilitated by the mechanical ventilator. VILI is a complex collection of lung deconstuctive elements that manifests itself in a number of forms in- cluding but is not limited to the following categories of ventilator induced lung injury; Volutrama, Barotrauma, Biotrauma, RACE and Atelectrauma. The calculation of the pulmonary time constant is essential in deter-


mining the tidal cycle indispensably important for avoiding dynamic hy- perinflation and ventilator induced or associated injury. The Pulmonary Time Constant (TC, Kt), is the product of the airways resistance times the static lung compliance in seconds that will allow for 63% of transferred volume to equilibrate. The time constant is the natural consequence of the lungs inherent capacity for expansion and resistance to airflow. The time constant will fluctuate in response to changes in resistance and com- pliance. Time constants may vary regionally. Gas moves into and out of the lung at a rate and in a fashion that is conditioned by the collective impedance of individual lung units. Lung units with high compliance will have a longer time constant; as will lung units with high airways resist- ance. Conversely, lung units with low compliance and low airways re- sistance will have a shorter time constant. The time constant of any individual lung unit may alter with the phase of ventilation and will vary with changes in the patient-ventilator system. (Think locally but treat glob- ally.) The time constant is calculated by multiplying the RAW times the CL. This is perhaps the most important calculated value in the manage- ment of the ventilated patient. The Rapid Shallow Breathing Index (RSBI), is the most reliable pre-


dictor of a patient’s potential for success in the weaning process. The clinician evaluates the patient’s breathing pattern by analyzing the re- lationship linking breathing frequency and average tidal volume. The RSBI is an accurate forecaster of the patient’s ability to perform en- durance related work and assume the work of breathing when extu- bated. The RSBI is calculated as the spontaneous frequency divided by the average spontaneous tidal volume in Liters, (f/VT). The patient is evaluated while breathing spontaneously without inspiratory adjuncts such as PSV. An index of <100 is a predictor of weaning success while an index of >100 suggests probable weaning failure. Peak Airway Pressure, (PAP/PIP), is the maximum airway pressure


recorded during an inspiratory cycle. This maximum or extreme pres- sure is usually actualized at the end of inspiration. This pressure reflects the collective result of machine and patient variables and is dynamic in character. The extreme pressure at the end of volume delivery. Mean Airway Pressure, (MAP), is the average airway pressure during


one complete ventilatory cycle. Also, the area under the pressure-time curve for one breathing cycle divided by cycle time. MAP is directly re- lated to PEEP and influenced by PAP, inspiratory time and inspiratory flow. NOTE: Frequently expiratory airways resistance is greater than inspiratory airways resistance. This will cause machines to underestimate true MAP. Auto-PEEP is the PEEP not set by the clinician. This PEEP represents a dynamic hyperinflation of the lung. PEEP that is present but not re-


Focus Journal Winter 2012 31


flected by the monitoring systems of the mechanical ven- tilator. The pressure gradient between alveolar pressure as set by the clinician, (PEEP or CPAP), and actual end expiratory alveolar pressure. Frequently a result of asyn- chronous ventilation, inadequate expiratory time, long pulmonary time constants or inadequate inspiratory flow. The prudent clinician will incorporate these various


elements: inspection, auscultation, time constant, plateau pressure, mean airway pressure, airways resistance, lung compliance, RSBI and P/F ratio into a comprehensive as- sessment dashboard from which a clear plan of care will emerge. I will devote future columns to the clinical ap- plication of these assessment tools.


Nov/Dec 2010 Management and Clinical Expertise for Respiratory Care & Sleep Medicine


FOCUS JOURNAL California Here We Come


Calif


The 11th Annual Focus on Respiratory Care & Sleep Medicine Conference


THE TOWN & COUNTRY RESORT - SAN DIEGO, CA March 24-26, 2011


Our Last Printed Issue


JUST SOME OF THE SPEAKERS PARTICIPATING


William Dement MD


Doug Masini PhD, RRT


100+ LECTURES 4 EARLY-BIRD BREAKFAST WORKSHOPS 2 KEYNOTE SPEECHES 2 EXHIBIT HALL RECEPTIONS 5-K RUN/WALK


• ENTERTAINMENT INCLUDING THE FABULOUS ICONS IMPERSONATOR CONCERT • • PLUS 2 GREAT NIGHTS OF • And Your Significant-Other Gets a Free Pass to the Entire Conference !


Bob Kacmarek PhD, RRT


Bill Malley MS RRT


Meir Kryger MD


Dana Oakes RRT


Carl Mottram RRT RPFT


Robin Woidtke RN RPSGT


John Salyer RRT, NPS


Pam Minkley RPSGT


Keep Receiving Focus Journal


ELECTRONICALLY Every Quarter


Make sure your e-mail


subscription is up to date by subscribing at


foocus.com/subscriptions.php


Managers & Educators Please inform your staff and students of their ability


to subscribe to the quarterly FOCUS Journal free


simply by subscribing at Foocus.com/subscriptions.php


Complete Program Inside


Keynote Speaker April Gochberg RRT


The Lung Redefined


Town & Country Resort $139/night!


100+ lectures, 20-22 CEU’s


Significant-Other registration FREE


plus two great nights of entertainment!


Keynote Speaker David Pelzer Author of


A Child Called It


NEW


Pre-Conference Sleep Educator Course


Pre-Conference


Asthma Educator Course Pre-Conference


Manager’s and Educator’s Mini-Conference


www.Foocus.com


July/Aug 2010 FOCUS JOURNAL Management and Clinical Expertise for Respiratory Care & Sleep Medicine


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44