Dead of Night shift

http://en.wikipedia.org/wiki/File:DeadOfNight1.jpg

After six years of being a day walker I have returned to my origin as a night shift healthcare provider. I enjoy the pace and the autonomy of night shift however, it is sometimes torturous. 

I feel like “Walter Craig” in the 1945 British film “Dead of Night”, in which the character experiences a recurring nightmare with the same cast of house guests. Instead of “Pilgrims Farm” I’m stuck in a hospital interacting with it's own recurring cast of personalities; the non-compliant patient, the substance abuse patient, the medical resident who thinks he’s M.D. “House”, the nurses who are fueled on cigarettes & Red Bull.  Yes, I’m dead of night shift; indifferent, cold, and apathetic. Additionally, night shift is slowly killing me.

Night shift work has been associated with a number of maladies including:

Metabolic syndrome [1& 2]

Increased vascular stress [3 & 4]

Induced Apnea [5]

In regards to me it is vitamin D deficiency. Yearly, I have a few blood tests performed to check for abnormal values. Before returning to night shift my previous vitamin D levels were normal, I lived in the Midwest, and had no additional vitamin D supplementation. After starting night shift I began supplementing my vitamin D intake with 1000 micro units/day & I also moved to the east coast (more sun), conversely my results were below normal. I always have these test performed in February, so the amount of sunlight/day/month is not a factor.

[1] Biggi, N. et. Al. (2008). Metabolic Syndrome in Permanent Night Shift Workers. Chronobiol Int.

[2] Pietroiusti, A. et. Al. (2010). Incidence of Metabolic Syndrome Among Night-Shift Healthcare Workers. Occup Environ Med.

[3] Lo, SH. et.al. (2010). Working Night Shift Causes Increased Vascular Stress and Delayed Recovery in Young Women. Chronobiol Int.

[4] McCubbin, JA. et. Al. (2010). Blood Pressure Increases During a Simulated Night Shift in Persons at Risk for Hypertension. Int J Behav Med.

[5] Laudencka, A. et. Al. (2007). Does Night-Shift Work Induce Apnea Events in Obstructive Sleep Apnea Patients? J Physiol Pharmacol.

Setting Ventilator Alarms Diagnostically

Many practitioners set alarm thresholds thoughtlessly due to the fact that many ventilators do a poor job of filtering alarm nuisances versus 'high-risk' alarms. Many times I see the high respiratory rate alarm set at threshold in which the patient would have severe air trapping and dynamic hyperinflation before the alarm threshold is met.

When using controlled modes of ventilation (VC-CMV & PC-CMV) it is extremely important to set the high respiratory rate alarm threshold appropriately.

During both machine and patient initiated breaths the inspiratory time is fixed, so any additional breaths takes away from the expiratory time which can quickly lead to a inverse inspiratory-to-expiratory (I: E) ratios.

How to set the High Respiratory Rate Alarm Diagnostically

In patients with obstructive airway disease I prefer to set my high
respiratory rate based on a 1:1, I: E ratio. 
That is when the patient sets off the high respiratory rate alarm I know that they are breathing at a 1:1 ratio and that any additional breaths will be an inverse I: E ratio, putting the patient at a increased risk for dynamic hyperinflation.

This is easy to calculate based on the patient's set inspiratory time.

Formula: x = 60/(I-time * 2)
X (high respiratory rate alarm)
60 (total cycle time)
I-time (machine set I-time)

A common I-time is 1.0 second this would equal a high respiratory rate alarm of 30 breaths/minute. This stays the same if the set rate is 8 or 25; the 1:1 threshold is at 30 breaths/min.

The 0.25 Second difference

If air trapping is a concern just decrease the I-time.
A 0.25 second change is significant. 


Decreasing the I-time from 1.0 second to 0.75 second increases the
alarm threshold to 40 bpm.

Low Peak Inspiratory Pressures During Adaptive Pressure Control Ventilation: an Indication for Weaning

Low Peak Inspiratory Pressures (PIP) during Adaptive Pressure Control (APC) may be a sign of distress in patients with increased inspiratory efforts (e.g. high metabolic rate, sepsis, and hypercapnea) [1], or may be a sign that the patient is ready for spontaneous breathing trials.




In the patient that is not in distress and the PIP is low (≤ 15 cmH20) consider evaluation for liberation. If the PIP is low one can presume that the patients’ pulmonary mechanics have improved or within the normal range and that the workload imposed by low compliances or high resistances have decreased.


Example Case


80 female patient with the following ventilator settings:


Mode- APC, Rate- 12, Vt- 500, Fio2- 35%, PEEP- +5 cmH2O


Discovered from the ventilator patient assessment that the patient’s PIP was only 13 cmH2O and the patient was resting comfortably. At this institution spontaneous breathing trials are performed with CSV-PS, Pressure Support of 7 cmH2O & a PEEP +5 (PIP total 12 cmH2O).


The measured PIP over the previous 48 hours was a ~ mean of 13 cmH2O.


This was significant, the patient was basically on the same control pressure as what this facility does SBT’s on, indicating that the patient should have been weaned or liberated 48 hours earlier.


After this finding the patient was immediately placed on a Trach collar trial. The trial was successful with no complications and the patient was transferred to a general medical floor within 48 hours.


Conclusion


Low PIP during APC ventilation should always be evaluated further for the potential for liberation from mechanical ventilation or the need for adjusting ventilator settings to decrease the work of breathing.

[1] The Problem With Adaptive Pressure Control Modes of Ventilation: a Case Study.

Delayed Cycling

One form of delayed cycling  is when the operator inappropriately sets the inspiratory time too
long.

However, delayed cycling is also very common during CSV-PS.

A pressure spike at the end of inspiration may indicate delayed cycling however this is not always associated with expiratory muscle activity . The spike may also be due to the relaxation of the inspiratory muscles, the spike is caused by the returning of pressure creating a temporary increase in pressure (usually associated with higher levels of pressure support > 10 cmH2O). 

Always evaluate the patient for distress to determine if it is delayed cycling vs. muscle relaxation. If the patient looks relaxed and the P0.1 is within limits then the spike is most likely due to muscle relaxation.

A 25% expiratory cycling threshold is a common default setting in most mechanical ventilators. This setting is appropriate in a large percent of the patient population. As previously mentioned a default setting of 25% may be too short in patients recovering from ALI, conversely , in patients with histories of airway obstruction this setting may be too long.


Prolonged expiratory cycling in the COPD patient may increase work of breathing, intrinsic PEEP, and trigger asynchronies (ineffective efforts).Waveform book  at 

Is the T-Piece Trial Futile? 3 Cases that Justify a T-Piece Trial.

In a current Blog posting “No More T-Piece” author Rick Frea states that at his facility T-piece trials are pretty much non-existent.

I don’t remember the last time I have preformed a T-piece trial on a patient with an E.T. Tube? It is very popular these days to perform the Spontaneous Breathing Trial (SBT) inline with the mechanical ventilator, due to the advance physiological monitoring and the extra alarm capabilities.

Most institutions I’m familiar with use a small amount of pressure support (~5 cmH2O) or Automatic Tube Compensation (a.k.a. Tube Comp, ATC, or Tube Resistance Compensation) if it is available on the machine to overcome the resistance of the artificial airway.

Even though the t-piece method is rarely used I believe it can be beneficial and more diagnostic in some cases to prevent false positives created by spontaneous breathing augmented with pressure support & PEEP.

3 examples:

Premature Cycling

Image 1: Patient coughing, notice the peak pressure spikes (yellow pressure waveform) this may lead to premature cycling. 

Premature Cycling
Premature cycling  also known as premature termination or short cycling occurs when the ventilator breath cycle ceases abruptly, while the patient requires a longer inspiratory phase. It is defined by the delivered inspiratory time is less than 50% of the mean inspiratory time [1,2].

Premature cycling may be attributed to pressure over-shots, causing the breath to cycle-off when the generated pressure meets the safety threshold setting. A good example of this is when a patient coughs during volume controlled ventilation (VC-CMV, VC-SIMV), in which the exhalation valve is closed throughout the set inspiratory time. 

Adaptive Support Ventilation: the “Pareto Principle” of Mechanical Ventilation.

One reader asked me “what do you think about ASV” (Adaptive Support Ventilation) in which I replied back “I think it is the Pareto Principle or Pareto Efficiency of mechanical ventilation”.

So what is the Pareto Principle?

Oral Exam: 99.9 % Failure Rate Among ICU Nurses

Question 1. What is pictured in image 1?

Image 1

Question 2. What is it used for?

If you answered “Bite Block” you must be an ICU nurse.

 I cannot count how many times nurses have tried to use the “oropharyngeal airway” as a bite block and complain about how the patient is fighting the tube & airway, gagging, and fighting the ventilator.

The next step, they usually heavily sedate or paralyze the patient.

An oropharyngeal airway is to help keep the airway patent (open) & should not be used in the conscious patient with a gag reflex.

Now this is a bite block (image 2), which can be used for that patient biting on an  E.T. tube. 

Image 2 "Bite Block"

SmartCare "Too Short for This Ride"

I remember when I was younger how upset I got over the fact that I was too short to ride a stand up roller coaster. It would have been not so traumatic; however my younger brother of two years was able to ride and antagonized me the rest of the day.

Yes, I was the Husky (short & chubby) kid and isolated from sports where height is an advantage.

Being too short for riding a roller coaster or playing basketball is a common occurrence, however what about being too short for a mode of mechanical ventilation?

Intrinsic PEEP (PEEP i)

Assessment of PEEPi based on a end-expiratory occlusion. Maneuver is high-lighted.

Intrinsic PEEP (PEEPi) is the difference between total PEEP and external PEEP, and provides information on the amount of dynamic hyper-inflation working on the respiratory system as well as the intra-thoracic organs. 

PEEPi has the same adverse effects of PEEP regarding both hemodynamics, barotrauma, and volutrauma.

PEEPi affects patient triggering by creating a inspiratory threshold load to be over come by the patient during spontaneous breathing.

Anesthesia Machines: Bellows vs. Piston

Correspondence 2008.

Attached are three documents:

1. Article on gas consumption in bellow driving anesthesia machines, comparing both Draeger & GE, this is one of the main reasons Draeger switched to a piston (to conserve on fresh gas, allowing for minimal flow anesthesia < or = 1/4 liter total fresh gas flow).

2. Abstract comparing the Apollo (piston) & Aisys (bellows) in regards to the accuracy of tidal volume delivery, with the new technology the Aisys can also accurately deliver both large & small tidal volumes. 

3. A letter I wrote to a customer on the limitations of the (Draeger's) Narkomed 2B (an older bellows machine) in regards to ventilating the morbidly obese patient. 

The Not So Smart, “SmartCare”

SmartCare/PS® or SmartCare Pressure support (™ Draeger Medical, Telford, PA) is the only automated weaning ventilator mode in the United States that relies entirely on a rule-based expert system[1]. Sales specialists are quick to insist that the software upgrade will pay for itself, and decease intensive care unit, ventilator days. 

Before considering such a large capital purchase expense, one should consider the following; "Is SmartCare quicker then in-place protocols?" PEEP restraints during spontaneous breathing trials, and high intrinsic diaphragmatic rates. 

SmartCare Pressure Support Mode Photos Link

Is it Quicker?

The term "automated" is a little misleading, since the practitioner first has to identify if the patient is even a candidate to perform spontaneous breathing trials.

After screening the patient the operator needs to change the mode to "Spontaneous", and make selections under the following categories; Body weight, Airway Type, Medical History, & Night Rest.

Entering patient data into these categories determine rules for the ventilator to follow, in regards to pressure support titration, respiratory rate limits, and end-tidal carbon dioxide limits (etCO2).

After initiating a SmartCare session (starting the mode), the ventilator adapts the level of pressure support[2] to maintain the patient in a "Zone of Respiratory Comfort"[3], slowly progressing to a spontaneous breathing trial (SBT) at the rule-based predetermined minimum pressure support[4].

The quickest a patient can transition and complete a spontaneous breathing trial from the initiation of SmartCare is one (1) hour and two (2) minutes. This is much slower then the many standard Respiratory Therapist Driven Weaning protocols I'm familiar with. The current SBT protocol at seven different hospitals I'm familiar with, the SBT trial time is thirty (30) minutes (this is for both surgical & medical patients).

So at these facilities with proactive weaning protocols, Smartcare would be unnecessary.

Positive Expiratory End-Pressure restraints

Another consideration with SmartCare is that it will not perform a SBT on PEEP settings ≥ 8 cmH2O. Some institutions will use higher PEEP during SBT's with the morbidly obese patients and patients that have trigger asynchronies, secondary to dynamic hyper-inflation.

 High diaphragmatic frequencies

Many patients receiving mechanical ventilation have high intrinsic diaphragm rates (≥ 30), even when very well assisted. This usually is unnoticed because the ventilator only measures machine or patient triggered breaths; however the patient's true rate may be higher. The practitioner may notice ventilator flow distortions, in which the patient is attempting to initiate a breath however the machine doesn't provide one (a.k.a ineffective efforts, or missed trigger attempts). 

Missed Trigger Attempts, notice the flow distortions (purple flow waveform) without associated breaths. Measured rate 12 bpm, however intrinsic rate 30 bpm.

This is a problem with the SmartCare classification models.

After pressure support is decreased and the patients true respiratory rate is unmasked (by the reduction in ineffective efforts)   a patient who has a rate of ≥ 30 bpm with no other manifestations of distress, will never be classified "Normal Ventilation", they will be classified as "Tachypnea" or "Severe Tachypnea".

 A seasoned Respiratory Therapist may notice that the patient is actually becoming more synchronous at the lower levels of support; the SmartCare model will fail the patient and increase the pressure support setting.

Dr. Magdy Younes stated in a lecture on ventilator synchrony[5], that in his sampled ventilator population that 50% of his ICU patients had a diaphragm rate > 30 bpm and 25% of these patients had a diaphragmatic rate > 35, even when very well assisted.

So, in this patient population SmartCare would be a poor choice for a weaning modality.

In my own ICU patients I sampled ~ 20 patients and I calculated that 7% had intrinsic diaphragmatic rates > 30, even in patients that the minute ventilation was 100% supported by the ventilator (e.g. 72kg IDW patient, preset minute ventilation of ≥ 7.2 liters).

Conclusion

SmartCare is an automated weaning platform which uses an intelligent control scheme to wean mechanically ventilated patients. Even though the system is automated the operator still needs to first determine if the patient is ready for SBT's and second select a few basic parameters before initiating the mode. In comparison to Respiratory Therapist Weaning protocols, SmartCare may be much slower in performing a SBT. In regards to higher PEEP levels and higher intrinsic diaphragmatic rates, SmartCare's models will not perform a spontaneous breathing trial in these patients.

---

[1] Chatburn, R. & Mireles, E. (2011). Closed-loop Control of Mechanical Ventilation: Description and Classification of Targeting Schemes. Respiratory Care. 1 (56).

[2] SmartCare continuously monitors EtCO2, Vt, & RR (measurements collected every 10 seconds). With these measurements the software classifies the patient status every 2-5 minutes. Based on the classification status the ventilator will ↑ or ↓ pressure support, or set-off an alarm condition.

[3] Zone of Respiratory Comfort is based on patients' weight selected & medical history.

[4] Minimum pressure support level is predetermined by Airway Type, active humidifier vs. heat moisture exchanger.

[5] Magdy Younes presented a lecture circa 2006, on ventilator asynchrony & PAV+ it was recorded for Covidien.

RELATED LINKS
New auto-weaning ventilator might make pulmonologist obsolete

Obtaining the MIP without a Manometer.

I always hate trying to find equipment, especially if your in the ICU & have to go to the basement where respiratory supplies are located. This quick trick is a very convenient way to obtain the Maximal Inspiratory Pressure at Low Volume, without a analogue pressure manometer.

Using Volumetric Carbon Dioxide Measurements to Optimize “P-High” During Airway Pressure Release Ventilation

There are many concerns when utilizing Airway Pressure Release Ventilation (aka. APRV, BiLevel, BiVent) in regards to lung injury.

 Inappropriate P-High settings may lead to large release-volumes resulting in over-distention, and volume induced lung injury [1].

Determinants and limits of the Draeger Narkomed Anesthesia machine in regards to ventilating the morbidly obese patient.

*Correspondence from 2007

Purpose

Determinants and limits of the Draeger Narkomed Anesthesia machine in regards to ventilating the morbidly obese patient.

A Problem with Plateau Pressures

When utilizing mechanical ventilation the plateau pressure is commonly evaluated to identify the potential for lung injury.  Many protocols (sepsis, ARDS) indicate targeting plateau pressures ≤ 30 cmH2O as a lung protective tactic.  

Unfortunately, in some patients the Plateau pressure may be falsely elevated and be relatively different then the transpulmonary/pleural pressure.

The MIP: a review of obtaining Maximal Inspiratory Pressure

“Breathe in as hard as you can”, a Respiratory Therapist yells to her ventilated patient. She is trying to coach the patient during a Maximal Inspiratory Pressure (MIP) maneuver, also known as the Negative Inspiratory Force (NIF).

This coaching is very common but is it necessary?

Can one obtain an adequate reading without coaching the patient or in a patient that is unresponsive?

First, think of the last time someone has had to yell at you, for you to initiate a breath?

It has probably never happen (not in less you overdosed on medication or illicit drugs)?

If the patient’s brainstem is intact and they have an adequate respiratory drive then a MIP can be obtained even if they are unresponsive.

So why do practitioners still yell at patients, & say the MIP is unobtainable?

Well it is most likely the result of poor technique.

So here are a few steps to guarantee that the technique is performed correctly, with measurable & reproducible results.

1. Patient criteria: the patient’s brainstem should be intact (no ischemic injuries).I don’t know why anyone would want to perform a MIP on a brain dead patient, when you should be performing an “Apneic Oxygenation Diffusion” test.

-One should caution performing the procedure in patients that are young, strong,

athletic, and have been mechanically ventilated for a short amount of time.  In these

stronger patients there have been incidences of rapid pulmonary edema secondary to

negative pressures created during inspiration against an occluded airway [1].

2. Respiratory Drive
   : the patient must have a strong inspiratory drive; the clinician must evaluate the common causes of a low respiratory drive (e.g. sedation, narcotics, hypocapnia, high levels of assist) and reverse/decrease these if they are present before the procedure.

3. Actively breathing: the patient must be actively breathing ideally in a spontaneous mode, or a partially assisted mode if needed. Make sure the ventilator is not auto-triggering.

4. Muscle Loading: the respiratory muscles should be loaded, by dropping support before the maneuver.

5. No muscle Fatigue: the patient should not be fatigue before the procedure, obtaining the MIP after a spontaneous trial will provide poor results.

Procedure

There are two main techniques used to perform the MIP. One is the Measurement at end-expiratory lung volume and the second is measurement at low lung volume.

Measurement at end-expiratory lung volume

This measurement is based on a total occlusion of the airway opening & easy to perform with the automated function of various newer mechanical ventilators.

The maneuver should be performed for at least 20 seconds or ten occluded efforts, and no longer than 25 seconds, making sure that the patients’ vital signs remain stable. 

Fig 1: MIP procedure performed on the Respironics Esprit Ventilator. 

Fig 1. Shows the maneuver for the MIP measurement obtained with the end-expiratory occlusion function of an Esprit ventilator. The maneuver starts at zero time and goes for 24 seconds. The first few efforts show negative deflations only in the range of -10 cmH2O. If one would end the procedure at this point one might assume that the patient is too weak. However, notice as the procedure is continued air hunger forces the patient to progressively increase his inspiratory efforts, which leads to a final measurement of -29.3.

The procedure should be repeated no more than twice.

Measurement at low lung volume

The second method is obtained below the function residual capacity (FRC); results are typically higher in this test since the respiratory muscles perform better under low lung volumes.

This test is performed with a simple t-piece device, & manometer. 

Example of a device used to obtain MIP at low lung volume

The test is performed by hooking up the patient per instructions, and occluding the ambient port at any time during the respiratory cycle.

Perform the test for the same amount of time, while assessing the patient for deleterious side effects.

Document the most negative number generated. 

RELATED POST

Obtaining the MIP without a Manometer

A Unique way to Obtain the NIF

Reference 

Lotti, G. & Braschi, A. (2009). Measurement of Respiratory Mechanics During Mechanical Ventilation. Rhazuns, Switzerland.

Negative Pressure Pulmonary Edema Reference

1. Postobstructive pulmonary edema following anesthesia - Elsevier

   by IA Herrick - 1990 - Cited by 25 - Related articles

   Keywords: Anesthesia, general; complications, airway obstruction, pulmonary edema; airway, obstruction, laryngospasm; lung, pulmonary edema ...
   ►
2. 
   

   Jornal Brasileiro de Pneumologia - Negative-pressure pulmonary ...

   
   

   by RK Mussi - 2008 - Cited by 1 - Related articles

   
   

   ... after procedures involving upper airway instrumentation. Keywords: Hemorrhage;Pulmonary edema; Airway obstruction; Abscess; Prostheses and implants. ...

3. Acute Pulmonary Edema Caused by Choking in An Adult Patient

   
   

   File Format: PDF/Adobe Acrobat - Quick View

   Noncardiogenic pulmonary edema, Airway obstruction, Choking. 1Department of Emergency Medicine, Hualien Armed Forces General Hospital,. Hualien, Taiwan ...

   
   

   www.tsim.org.tw/journal/jour18-2/07.PDF - Similar
4. 
   

APRV: Setting P-High based on the Static Pressure Volume Curve

Some newer mechanical ventilators provide the operator with automated tools to obtain a static Pressure Volume (P/V) Curve in the ventilated patient. These tools provide the clinician a simple, safe, and reproducible method to assess the P/V curve for various pulmonary conditions. 

Photo 1: Hamilton G5 ventilator screen, showing the "P/V tool" software to obtain a static P/V curve.

The Constant Low Flow Method: Utilizing the PB840 part two (video)

Additional Reading:

The Acute Effectiveness & Safety of the Constant-Flow, P/V Curve to Improve Hypoxemia in ALI.

Identifying Optimal PEEP with the PB 840 Ventilator: the "Constant Low Flow Method"

Evaluating the Pressure/Volume curve for the lower inflection point, provides the operator a idea of where to appropriately set the level of PEEP. The curve identifies where lung recruitment begins and at what pressure/volume creates over distention and/or injury.

In newer generation ventilators (Draeger's Evita XL or Hamilton's Galileo or G5 platforms) obtaining the static pressure/volume curve at a low flow state is simple via the machines automated tools.

Conversely, in other ventilators obtaining a static low flow P/V curve can be complicated if not impossible to perform.

The PB 840 does not have a automated tool for performing a "Low Flow" maneuver, however the practitioner can do the maneuver manually using the following steps (1):

The "ASV Target Point": Adjusting the %MinVol setting During Adaptive Support Ventilation

After a few years of implementing Adaptive Support Ventilation (ASV), I still receive questions from staff members and physicians regarding the ideal %MinVol target setting when initially setting-up ASV. I usually respond by asking, “do you want to wean or rest the patient”?

Shook to Death: a Case Study of High-Frequency Chest Wall Compression

Background

There are a variety of techniques used as "Chest Physical Therapy" (CPT), for patients with airway diseases. The main goal of these therapies is to augment secretion mobilization & airway clearance[1].

One of these techniques utilizes high-frequency chest wall compression a.k.a "The Vest" (® Hill-Rom). The manufacturers of the Vest list numerous conditions that the device may be used for, from patients with chronic respiratory conditions-to-Acute Respiratory Distress Syndrome[2].

Conversely, there are no contra-indications, considerations when not to use the device, or patients that may be at risk listed in the product information.

Waveform of the week: Drive pressure too low

Driving pressure or set pressure during mechanical ventilation utilizing a pressure targeted mode (PC-CMV, PC-IMV, PC-CSV) may be inadequate for patients' inspiratory flow demands. 

A peak pressure of 15 to 20 cmH2O is generally needed to provide significant support if the goal is to off-load work of breathing and/or resting the patient.

By evaluating the flow waveform the operator can identify a appropriate pressure setting to meet patients inspiratory efforts. The flow waveform should have a constant linear deceleration for the inspiratory phase & a   constant acceleration to baseline during the expiratory phase. 

During the inspiratory phase once flow starts to decelerate it should not rise again. If the flow rises again this is a sign of an increased respiratory drive & that the pressure setting is too low. The below picture provides a example of both a normal flow waveform pattern & the dis-synchrony related to a high respiratory drive. 

Inadequate driving/set pressure during PC-CMV as evidence by 'camel backing' flow rising after  deceleration.

RELATED POST

What the heck is P0.1?

Obtaining P0.1 on various ventilators. 

A Quick & Easy Way to Set "T-Low" During Airway Pressure Release Ventilation

A quick & easy way to initially set "T-Low" during Airway Pressure Release Ventilation is to use the "Expiratory Time Constant (RCexp)". The RCexp indicates alveolar emptying time and it takes at least 4 time constants for adequate alveolar emptying (~99%).

References state set T-Low to obtain a "Peak Expiratory Flow Rate Termination Point (T-PEFR)" at 50 to 75% of the measured "Peak Expiratory Flow Rate"

UTILIZATION OF PROPORTIONAL ASSIST VENTILATION FOR PATIENTS WHO FAIL A SPONTANEOUS BREATHING TRIAL

Background
Unloading ventilatory muscles has been a primary issue with our ventilator population. After analyzing ninety samples, it was revealed that 81% of the failed spontaneous breathing trials (SBT) were related to rapid, shallow breathing. Our original process for resting patients who have failed a SBT was to ventilate the patient utilizing “Volume Control Ventilation plus” (VCV+). One disadvantage of using an assisted mode for resting patients is the inability to properly set the ventilator to provide adequate rest without over resting the ventilatory muscles. Another disadvantage is patient/ventilator asynchrony, which may occur at any phase of breath delivery. A study of “Proportional Assist Ventilation” (PAV) was initiated to explore potential advantages over VCV+.

The Problem with Adaptive Pressure Control Modes of Ventilation: a Case Study.

Introduction

Adaptive Pressure Control (APC) is a ventilator modality, which has been applied safely in ICU’s for greater than a decade.The mode delivers a pressure control breath that maintains a ‘target’ operator selected tidal volume (Vt) at the lowest possible pressure independently of changes in pulmonary mechanics (1).

APC is a very popular mode and readily available on various ventilators (fig. 1). What has made this mode so popular is that the practitioner can set a Vt & the flow is variable.

EFFECT OF THE RAPID RESPONSE TEAM ON RESPIRATORY AND CARDIOPULMONARY ARRESTS WITHIN NON-CRITICAL CARE UNITS

Background: Rapid Response Teams (RRT) are groups of healthcare practitioners who respond to acutely-deteriorated hospitalized patients. Various studies have shown that RRT’s may improve patient outcomes. Additionally, the Institute for Healthcare Improvement recommends the implementation of RRT’s as one of their initiatives to improve patient safety outcomes. 

Objective: We implemented an RRT (An Internal Medicine Physician, Registered Respiratory Therapist, Critical Care Registered Nurse and Nursing Supervisor) at Sentara Careplex Hospital in 2005 specifically to reduce the monthly rate of respiratory and cardiopulmonary arrests (codes) external to the intensive care units.

Design: Single center, non-randomized, prospective chart review.

Setting: 199 bed community hospital.

Interventions - The records of patients who required cardiopulmonary resuscitation external to the intensive care areas were reviewed before RRT implementation to determine activation criteria for the RRT. Codes were defined as respiratory or cardiopulmonary arrest. The incidence of these non-ICU codes before and after RRT implementation was recorded. The one-way analysis of variance (ANOVA) was used for statistical testing of differences between years 2004 (pre RRT implementation), 2005, 2006, and 2007. A p value < 0.05 was considered statistically significant.

Results: Previous to RRT implementation, the non-ICU code rate averaged 5.33 events per month. After implementation, the mean non-ICU code rate decreased by an average of 21%. Conversely, when testing for significant differences between pre & post RRT implementation, there were no statistical differences among the four years (p-value 0.15).

Conclusion: Although our facility met its goal by decreasing the non-ICU code rate by 10%, there was no significant statistical difference pre & post RRT implementation. The cost of intensive care unit length of stay and unplanned ICU admissions is of great relevance. Additionally, patient-centered outcomes such as health-related quality of life and hospital mortality rates must be addressed.