Table of Contents

ABG Challenge - January, 2017
Respiratory Update Corner - Jan, 2017
Respiratory Update Corner - Jan, 2017
ABG Challenge - October, 2016
Respiratory Update Corner - Oct, 2016 (part 1)
Respiratory Update Corner - Oct, 2016 (part 2)
Arterial Blood Gas Challenge #1
Respiratory Update Corner - Sept. 2016
Respiratory Update Corner - Intro

ABG Challenge - January, 2017

24 Jan 2017

A 69-year-old female is brought into the emergency department by the local EMS. Her husband called 911 when she became minimally responsive at home. He reports that she has experienced an increase in shortness of breath for the past several hours, in spite of increasing the liter flow on her oxygen concentrator and using her albuterol inhaler. She has a long history of COPD. Her most recent hospitalization was three months ago.

Physical examination reveals a cachectic female who is borderline obtunded. Her respirations are rapid and shallow; breath sounds are distant.

Arterial blood is drawn for analysis while the patient is receiving oxygen via nasal cannula at 4 Lpm.

pH 6.96 PaCO2 136 mmHg HCO3 29 mEq PaO2 94 mmHg SaO2 89% CO 1.9% Hgb 10.2 g/dL Lactate 1.4 mmol/L


1. What is your interpretation of these blood gas data?

2. Why is the SaO2 so low?

3. Do you believe this patient is hypoxic?

4. Based on these data, what would you do at this point?


Respiratory Update Corner - Jan, 2017

20 Jan 2017

Continuing from our mid-January blog, we have some additional studies to review.

4) The ACCP and ATS have released new clinical practice guidelines for mechanical ventilation. Specifically, these address liberation from mechanical ventilation. The guidelines were published in this month’s (January) issue of Chest.

A couple of the recommendations caught my attention (although certainly no great epiphany). One was the following (quoted from the review): “Acutely hospitalized patients who have been on mechanical ventilation for more than 24 hours, are at high risk for extubation failure, and have passed a spontaneous breathing trial should be extubated to noninvasive ventilation.” This recommendation goes along with contemporary wisdom that the longer a patient stays in ICU, the greater the risk of developing various complications (e.g. infections, lung injury, etc.).

Another recommendation involves using pressure augmentation during the spontaneous breathing trial. Also included were the recommendations of attempting to minimize sedation and encouraging early mobility. As I indicated above, these are not radical departures from what has been studied and recommended in the past. The recommendations have now been ‘protocolized.’

5) A number of articles and studies have been reported recently dealing with oxygen use. I will review the highlights of a few of these below.

a) A study reported in HealthDay apparently showed: ‘oxygen therapy may not help patients in the less severe stages of COPD.’ The report didn’t fully outline what exactly is meant by ‘less severe stages of COPD. The post hoc analysis of the study was relatively ambivalent as to the clinical implications.

Just as a personal note: I’m not sure that this study is the epiphany the reports seemed to make it out to be. The Medicare guidelines (obviously in the US) for home oxygen have been have very well spelled out.

b) The following was the conclusion of a study in JAMA: “High-flow conditioned oxygen therapy was not inferior to noninvasive ventilation for reducing reintubation and post extubation respiratory failure.” Apparently, this study was done on patients at high-risk.

I have more-or-less believed in the potential of high-flow oxygen therapy since I first saw it (and tried it for myself) many years ago. I would like to know how you’re using it in your institutions.

c) The results of the Oxygen-ICU trial (recently reported at the annual congress of the European Society of Intensive Care Medicine and published in JAMA) were interesting. The trial compared the mortality outcomes of ICU patients when placed on conservatively controlled oxygen therapy versus (what they called) the conventional, more liberal approach (in which patients are often kept in a hyperoxemic state).

The results of the trial showed the rate of mortality was 11.6% with the conservative therapy (defined as maintaining a PaO2 70 and 100 mmHg or a SpO2 between 94% and 98%) whereas the mortality rate for the conventional group (PaO2 up to 150 mmHg or SpO2 between 97% and 100%) was 20.2%. In addition, while there was no difference in ICU length of stay, the patients in the conservative group spent (on average) a day less on mechanical ventilation.

This was a relatively small study (480 patients enrolled), but the results are interesting. In my clinical career, I have noted the majority of patients I saw in the ICU had SpO2s (displayed on the monitor) of between 99% and 100%. We know from looking at the calculation for total oxygen content that there is little difference in content as the PaO2 rises above 70 mmHg or so or the SpO2 is above 95%. What price are these patients paying so that we clinicians can feel good?

d) Finally, the results of the 2015 AVOID trial seem to confirm what researchers have suspected for several years. The following quote is taken from an article recently published Chest Physician that references AVOID: “Results from the AVOID trial report that routine oxygen use in normoxic patients hospitalized with a heart attack was not beneficial and, in fact, was harmful. Patients who received oxygen had more myocardial injury than those who did not.”

It is, perhaps, worth noting the following recommendation from the American Heart Association (updated ACLS standards): “When resources are available to titrate the FiO2 and to monitor oxyhemoglobin saturation, it is reasonable to decrease the FiO2 when oxyhemoglobin saturation is 100%, provided the oxyhemoglobin saturation can be maintained at 94% or greater.”

Based on the c and d above, have you seen a change in the use of oxygen therapy in your ICUs?


Respiratory Update Corner - Jan, 2017

19 Jan 2017

Greetings and welcome to the third edition of my blog. Just a reminder that this blog is meant to be a review of recent studies and data primarily related to respiratory medicine. The blog is also meant to be interactive. I would greatly appreciate your feedback. Please address any comments, questions, or concerns to me at Remember: Health care delivery is fascinating, demanding, dynamic, and ever-changing. No one has all the answers (or even all the questions), so don’t be afraid to jump into the fray, express your opinion, share your experience. Your contributions will only serve to strengthen the profession. In addition, if you would like a copy of the first two blogs, please contact me.

Okay, there’s been a lot of interesting stuff related to respiratory medicine in the medical news over the past few months, certainly more than I can report here, but we’ll see if we can at least mention a few of the most relevant (in my opinion, anyway).

1) A number of reports of studies have demonstrated the superiority of LABA/LAMA over LABA/ICS (LABA = long acting beta agonist; LAMA = long acting muscarinic antagonist; ICS = inhaled corticosteroid) in the treatment of COPD. The most widely reported is the FLAME study. This study looked at the combination of indacterol and glycopyrronium versus the combination of salmeterol and fluticasone. The outcome was the number of exacerbations in a year.

While this is an interesting and well-done study, I can’t help wondering how much of an effect the results will have on prescribing patterns. I have known many people with COPD who are on a LABA/ICS combo plus a LAMA (usually tiotropium). Also, as I have indicated before, clinicians need to consider the cost and availability of these medications as well as the patient’s ability to use them properly.

Another study, the CRYSTAL study looked at improvements in lung function (specifically FEV1) in patients with moderate COPD. They used the same combination of LABA/LAMA and showed positive results. It is probably worth noting, however, that this study was sponsored Novartis.

Interestingly (and perhaps ironically), at the same time the FLAME study was being reported, two other large studies confirmed (based on the data) that triple COPD therapy was superior to monotherapy. These studies were the TRINITY and the TRILOGY. TRINITY compared a combination of LABA, LAMA, and ICS to LAMA alone. TRILOGY compared triple therapy with the combination of ICS and LABA. In both studies, the triple combination resulted in better outcomes. It is worth noting that the drug combos, methodologies, and outcomes were slightly different between studies. I guess now we need a study that compares the triple therapy with LABA/LAMA combo using the same drugs.

2) A small study reported in Medscape showed that scrubs can become contaminated with bacteria. The study looked at 40 ICU nurses and found the transmission of six types of bacteria. Some transmission was from patient to nurse; some was from nurse to patient.

This sort of falls in line with recent discussions involving the potential contamination of clinicians’ clothing, including lab coats. One report estimates that 722,000 healthcare-associated infections occur in US hospital, resulting in about 75,000 deaths each year. While this is certainly a serious problem, apparently the jury is still out on the role clothing plays in infection transmission. On the other hand (no pun intended), no one questions the value of diligent hand hygiene. Please pass along to me (see contact information above) what you are doing in your facility to promote hygiene (i.e. changes in uniform policies).

3) A review of 20 perspective studies and published in BMC Medicine apparently found that a ‘handful of nuts a day may be enough to reduce the risk for death from heart disease and other ills.’ According to the report, researchers found that people who ate the most nuts reduced their risk of coronary heart disease, cardiovascular disease, and cancer. They also found a reduced risk for respiratory disease, diabetes, and infectious disease.

I admit that I didn’t track down the original study so I can’t say how the review was conducted or, perhaps more importantly, which nuts were used. As I read the results, I couldn’t help wondering if peanut butter counts. Also, what about all those poor people with nut allergies?

It will be interesting to see if more studies are done and what the results might be. Also, I wonder if these results will somehow be tied to the very recently reported news that exposing infants to nuts may possibly reduce the risk of developing nut allergies later in life.

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