Saturday, May 28, 2011

The Utilization of Mid-Frequency Ventilation with a Sophisticated Transport Ventilator: a Case Study


Mid-Frequency Ventilation was first described in the medical literature by Mireles-Cabodevila & Chatburn in 2008 [1]. The authors describe Mid-Frequency Ventilation (MFV) as setting ventilator frequencies greater than 35 cycles per minute, during Pressure Control-Continuous Mandatory Ventilation (PC-CMV) to provide increased minute ventilation support in patients with severe Acute Respiratory Distress Syndrome (ARDS). In this initial article the authors tested their theory on both a computer simulation model and bench study using newer generation conventional intensive care unit ventilators. Both test simulations where successful.

In 2010 Mireles-Cabodevila & al. applied the theory in a live neonatal & pediatric animal model; the results reinforced the previous hypothesis showing the potential benefits of MFV [2].

As of to date there have been no cases reported in the medical literature of MFV being applied in humans. I previously presented a case where MFV was applied for a patient with serve hypercapnia; however this was never submitted for publication [3].

The following case involves using MFV on a sophisticated transport ventilator, thus reinforcing the versatility of MFV. The operator does not need a special ventilator (e.g. oscillator) or mode (e.g. APRV). Even though one does not need a specific ventilator the device still needs to safely and effectively ventilate injured lungs. The transport ventilator used during this case is considered a “sophisticated” transport ventilator, one that can effectively ventilate injured lungs [4].

Wednesday, May 25, 2011

Chest Physical Therapy Catastrophes

Chest Physical Therapy (CPT) is ordered at many institutions for numerous conditions, from patients with chronic respiratory conditions-to-Acute Respiratory Distress Syndrome. The main goal of these therapies is to augment secretion mobilization & airway clearance[1]. Even though CPT is ordered liberally it does have associated risks and there is no supporting evidence that CPT is more valuable than a direct cough (Schans, 2007). At one institution I work at there have been 4 adverse events related to CPT in a short six month time span. I previously described two of the incidences on the same patient in the posting Shook to Death: a Case Study of High-Frequency Chest Wall Compression”. The other two cases will be presented.

Case 1
An 83 year old patient whose initial compliant was for abdominal pain and nausea and vomiting. The patient was ordered CPT via Vest every four hours for unknown reasons (probably because the physician observed COPD in then dictated medical history). The patient’s pre-existing medical history included COPD, atrial fibulation, and left lung resection.  CPT was initiated and the patient immediately went into atrial fib, the therapy was stopped to make sure the vibrations did not cause an inappropriate reading of the ECG. The A-fib remained present after stopping the CPT and the patient had to be medically treated for her symptoms. Thus increasing her ICU observation period.

Case 2
A 60 year old female patient admitted for respiratory distress was ordered CPT via percussion secondary to a left lower lobe infiltrate. The patients pre-existing medical history included cardiomyopathy, diabetes, hypertension, chronic renal insufficiency.
During the CPT procedure the patient experienced cardiopulmonary arrest, secondary to mucus plugging. The patient was resuscitated, placed on mechanical ventilation, and bronchoscopy was performed the following day. The patient had a lengthy intensive care unit stay and was eventually discharged.

CPT is a commonly prescribed therapy, with little evidence of success. Practitioners’ should be aware of the risk factors associated CPT and screen patients appropriately for their ability to clear the mobilized secretions. Always, consider if there is a rational for CPT and which therapy is likely to provide the greatest benefit with the least amount of harm.

[1] Schans, C. (2007). Conventional Chest Physical Therapy for Obstructive Lung Disease. Respiratory Care. 52 (9): 1198.

Sunday, May 22, 2011

Ten Reasons to Trade in the Babylog 8000

Image 1 : Front view of the Babylog 8000 neonatal ventilator.

The Babylog 8000™ (Draeger Medical, Telford, PA) is a neonatal specific ventilator that has been in use for over twenty years. At inception the Babylog was a unique platform providing high-tech applications in regards to breath delivery. This advance technology surpassed the available devices and provided a foundation for present day neonatal ventilators. Even with the success of this ventilator platform there are reasons one may consider trading in their machines.

The rationale for replacing the Babylog is related to technological advances, the lack of upgrade availability, and safety concerns.

Wednesday, May 18, 2011

Airway Obstruction Secondary to Growing Granulomatous Tissue in the Tracheostomy Tube

 Introduction: Airway patency is arguably the most important factor of the cardiopulmonary system. It is imperative that the bedside Respiratory Care Practitioner (RCP) can rapidly detect and treat airway emergencies. One tool for assisting the RCP in detecting airway displacements and obstructions is the use of capnography. At our institution capnography is routinely used for confirmation of tracheostomy placement following tube placement or tube changes. This case study presents the effectiveness of capnography for detecting a partial airway obstruction with the correct placement of the tracheostomy tube.

Sunday, May 15, 2011

The Intrinsic Diaphragmatic Frequency

Image 1: Missed trigger attempts, notice the flow distortions (purple flow waveform) without associated breaths. Ventilator measured rate 12 bpm, however true intrinsic rate 30 bpm. 

Many patients receiving mechanical have high intrinsic diaphragmatic rates (≥30 breaths per minute) even when very well assisted [1]. This is usually unnoticed because the ventilator only measures machine or patient triggered breaths; however the patient’s true respiratory rate may be higher. This can be problematic when performing a spontaneous breathing trial (SBT) for a couple of reasons.

Wednesday, May 11, 2011

Adaptive Pressure Control Ventilation and Severe Sepsis a Grueling Combination

Mentioned in previous postings Adaptive Pressure Control (APC) should be used cautiously in patients with high inspiratory drives. In patients with sepsis APC can become problematic by weaning the driving pressure prematurely due to a vigorous respiratory drive associated with lactic acidosis. The lower driving pressures will not efficiently off load the respiratory muscles leading to increased work of breathing, ventilatory muscle fatigue, and may initiate lung injury. 

Provided are two examples of APC utilized in sepsis patients:

Sunday, May 8, 2011

The Least Work of Breathing: Applying principles of Adaptive Support Ventilation

Adaptive Support Ventilation (ASV) is an advanced closed-loop mode of ventilation only available on Hamilton Medical ventilators (G5, Galileo, C2) in the United States.

ASV is considered an “Optimal” mode of ventilation, in which the ventilator automatically adjusts multiple set-points (pressure, tidal volume, frequency, & I: E ratio). Furthermore, the ventilator applies a mathematical model (Otis equation) to find the least work of breathing.

Providing minimal work of breathing is a primary goal for the mechanically ventilated patient. A load that is too high will eventually lead to ventilatory muscle fatigue and may lead to lung injury and/or liberation failure. Every practitioner should attempt to minimize the work of breathing (WOB) by continuously assessing the patient ventilator interaction and adjusting settings appropriately.

If available the practitioner could employ ASV, however what if you don’t have a Hamilton ventilator or unfamiliar with ASV?

Wednesday, May 4, 2011

The RT Hoarder

I admit I have turned into a hoarder, not the typical hoarder seen on television living amongst their bodily waste or sharing their house with 50 cats. My story is not as disturbing and goes unnoticed.