SBO Ultrasound

The GistAs mentioned in this post, the operating characteristics of historical and physical features are suboptimal in small bowel obstruction (SBO).  Bedside ultrasound has better operating characteristics and is one of the easier scans to perform and read.  Assuming others like to make their lives easier, I gave a talk on this; but professionals have created a tutorial at The Ultrasound Podcast tutorial.

I delivered a quick talk at the Controversies and Consensus in Emergency Medicine Conference on ultrasound for SBO, a modality that I've found great utility for in my developing practice. As a believer in Free Open Access Medical education (FOAM) and with hopes that, as a novice I might receive some constructive criticism to help me become better, I have posted the recording.

A Few Tidbits (some redundancy from prior post): 
Time.  Ultrasound for SBO is quick and easy and can be performed in conjunction with the history and physical exam in appropriate patients.  This may alleviate the time to definitive diagnosis (say CT or surgical evaluation), treatment, and/or disposition.*  Furthermore, sometimes we see things we don't expect on ultrasound.  Familiarity with US findings of SBO may make sense of dilated loops of bowel or altered peristalsis encountered during a gallbladder or aorta scan for abdominal pain.  Conversely, there are times when SBO may be suspected and a quick ultrasound may reveal an alternative diagnosis that may grossly change management (examples in talk).

X-rays are out for SBO.  Bedside ultrasound has better operating characteristics than plain films with fewer instances of equivocal results.  Sometimes plain films are crucial to evaluate for pneumoperitoneum but most patients with abdominal pain don't fall in this category.  Indeed, The American College of Radiology conclusion on plain films in suspected SBO
"In light of these inconsistent results, it is reasonable to expect that abdominal radiographs will not be definitive in many patients with a suspected SBO. It could prolong the evaluation period and add radiation exposure while often not obviating the need for additional examinations, particularly CT" [5].
  • Ileus vs. SBO - while US beats plain films with regard to percentage of ambiguous scans, ultrasounds can be equivocal as well.
  • Cause of obstruction/Transition point not well elucidated.  In patients with recurrent SBO from malignancy or adhesions and this may be less important to the managing team and surgeons often stop ordering CT scans if the presentation is consistent with prior presentations. 
  • Consultant access to images obtained at the bedside.
Note:  I have not included surgical consultants requiring a CT scan as part of the limitations.  The surgical literature recognizes the capacity of US to diagnose SBO, although this is not yet widely adopted [6].  However, despite common assumptions, surgeons don't require a CT scan for every recurrent SBO.  As a result, sometimes a positive ultrasound, followed by plain film, may be enough in these patients who will undergo conservative management.  Have a chat with each consultant, they're not always as inflexible as we make them out to be. 

*NCT02190981 pending with LOS as secondary outcome

1.  Carpenter CR, Pines JM. The end of X-rays for suspected small bowel obstruction? Using evidence-based diagnostics to inform best practices in emergency medicine. Acad. Emerg. Med. 2013;20(6):618–20.
2.  Taylor MR, Lalani N. Adult small bowel obstruction. Acad. Emerg. Med. 2013;20(6):528–44.
3. Böhner H, Yang Q, Franke C, Verreet PR, Ohmann C. Simple data from history and physical examination help to exclude bowel obstruction and to avoid radiographic studies in patients with acute abdominal pain. Eur. J. Surg. 1998;164(10):777–84. 
4. Jang TB, Schindler D, Kaji AH.  Bedside ultrasonography for the detection of small bowel obstruction in the emergency department. Emerg Med J. 2011 Aug;28(8):676-8.
5. Katz DS, Baker ME, Rosen MP, Lalani T, et al, Expert Panel on Gastrointestinal Imaging. ACR Appropriateness Criteria® suspected small-bowel obstruction. Reston (VA): American College of Radiology (ACR); 2013. 10 p.
Maung AA, Johnson DC, Piper GL et al. Evaluation and Management of Small-Bowel Obstruction.  J Trauma. 73(5):S362-S369, November 2012

Euboxia – Not Necessary (Or Necessarily Normal)

The Gist:  In medicine, we historically strive towards achieving values that fall within a reference range, or are normal, a phrase coined "euboxia" [1].  Targeting treatments to normalize values may not result in patient-oriented benefit and may cause harm.  We must also consider that normal values may not necessarily be normal for our patients.  Data fatigue, the exposure to copious data, may lead to ignoring values that are not flagged as abnormal, regardless of the appropriateness for a patient.
"'Euboxia' (from the Greek 'eu' meaning good, normal or happy, and 'box' from the tradition of writing physiological variables in boxes) is a colloquial word used in many North American and other hospitals to describe the state of apparent perfection aimed at by residents by the time they present their patients on morning rounds" - MC Meade [2].
Euboxia Is Not Always Necessary
Chris Nickson's Free Open Access Medical education (FOAM) post on Euboxia highlights some of the pitfalls with this obsession with normalcy. He also delivered a talk Euboxia and (ab)Normality at SMACC Gold which will hopefully be available on the SMACC podcast in the near future. A few examples include:
  • Hemoglobin transfusion trigger in anemia - Studies such as TRICC, CRIT, SOAP, and TRISS demonstrate that transfusion targets of more "normal" hemoglobin levels is not advantageous and may incur increased risks.  As such, transfusion triggers, in the absence of active myocardial ischemia, have moved to <7 g/dL while uptake of this trigger remains low in some communities [4]. 
  • Oxygen saturation in COPD - Unless patients are under duress, guidelines suggest patients with COPD have oxygen saturations targeted to 88-92% rather than the 98-100% more often associated with perfection [5]
  • Blood gas and saturations in ARDS - Guidelines for ventilation in patients with ARDS aim to protect the lungs using low tidal volumes and plateau pressures at the expense of allowing a pH of 7.20, permissive hypercapnia, and lower oxygen saturations of 88-95% (paO2 55-80 mmHg).  Correction of these lab abnormalities may come at the cost of additional lung damage by means of higher pressures or volumes and are thus discouraged [6].
Euboxia Is Not Necessarily Normal
Euboxia, however, may fool also practitioners into a false sense of security.  Failure to truly see a value that appears normal and isn't flagged, red, or outside of the box may be problematic. A few examples:

Normotension - Hypotension typically refers to systolic blood pressure <90 mmHg or a drop in systolic blood pressure >40 mmHg.  The latter part of this definition is often unable to be determined (due to lack of information) or forgotten.  The trauma literature seems to have solidified around the notion that the widely accepted definition of hypotension does not apply to many trauma patients, particularly those > 65 years old, and that 110 mmHg is probably a better cutoff [9-12].  While these recommendations have been out since 2011,  90 mmHg remains the common cut point for hypotension.
  • The CDC triage guidelines/"National Trauma Triage Protocol" have suggested <110 mmHg as the new hypotension guideline in patients > 65 years of age as multiple registry studies have demonstrated that an SBP <110 mmHg is associated with increased mortality and has an improved AUC compared with other blood pressure cut offs [9]. 
    • An abstract presented at AAST in 2014 found that patients >65 y/o with an SBP 90-109 mmHg had an odds of mortality of 9.7 (95% CI 8.7-10.8, p<0.01).  This survey study found improved, but terrible sensitivity for Trauma Center Need (ISS>15, ICU admit, urgent OR, or ED death) with the higher SBP cut-off [10].
Normal White Blood Cell Count (WBC) - Leukocytosis is often used as a predictor of infection/inflammation and historically loved by surgical services, yet the operating characteristics don't perform that well.  During a lecture as a medical student Dr. Sean Fox (PEM Morsels) shared the following perspective on the WBC, "WBC is the last bastion of the intellectually destitute."
I soon discovered that the sensitivity and specificity of leukocytosis, or the absence thereof, wasn't helpful in many situations.
  • In acute cholecystitis, for example, the WBC proves unhelpful as demonstrated by the following operating characteristics for leukocytosis: +LR 1.5; -LR 0.6; Sensitivity 63%; Specificity 57% [13].  Thus, a normal WBC does not help rule out acute cholecystitis.  Similarly, a normal WBC does not exclude acute appendicitis, although values <8 (a normal value) may have some utility in this regard according to Bundy et al.  
Normal Potassium in DKA - The reference range for potassium runs approximately 3.5-5 mEq/L.  Patients presenting in DKA may have low normal potassium concentrations but have severe total body potassium deficits.  As a result, professional societies recommend withholding insulin if a patient has a potassium <3.5 and supplementing potassium even when values are well within the upper "normal" limit of 4-5 mEq/L [14].  Despite these teachings and nearly habitual practice, without mindful attention to the potassium the "normal" lab value could easily be ignored. 

Normal Lactate - Lactate is beloved in Emergency Department (ED) care and it's well accepted that elevated lactate values predict mortality.  Yet, normal lactate levels may be falsely reassuring.  Lactate has been used as screening test in mesenteric ischemia as small, early reports yielded a sensitivity of 100% [15].  More recent analysis, however, show that the +LR 1.7 (1.4–2.1), -LR 0.2 (0–2.9) for L-lactate.  The -LR for lactate crosses 1.0, demonstrating that a normal lactate is not useful in crossing mesenteric ischemia off the list [16].  While we may cognitively understand this notion, in practice I think we quite often feel reassured by normal lactates (or reassure the admitting teams).

What to do?
Data overload and obsession may engender a sort of "data fatigue."  It is difficult to notice abnormalcy in data that may appear, for most individuals, normal.  This may be particularly arduous in a sea of numbers.  Furthermore, our attention is typically drawn to the red or flagged "abnormal" numbers.  This is not to suggest that we should agonize over every value and cannot trust anything "normal."  Rather, it seems that the signal in medicine is that tests and parameters are only as good as the context of the patient and the provider interpreting them. Here's what I'm trying, to combat my own data fatigue and subconscious euboxic thinking:
  • Think about a patient's clinical context, which requires mindfulness in the fast pace and overwhelming environment we call an ED.
  • Order a test?  Review the results (really), paying attention and process the results in the context of the patient.
  • If possible and appropriate, prevent data overload and data fatigue by ordering tests that will add value to the care of the patient.
1.  Reade MC. The pursuit of oxygen euboxia. Anaesth Intensive Care. 2013;41(4):453–5.
2.  Reade MC. Should we question if something works just because we don’t know how it works? Crit Care Resusc. 2009;11(4):235–6. 
3. Nickson CN.  Don't Put Your Patient In A Box.  Life in the Fast Lane. 
4. Carson JL, Grossman BJ, Kleinman S et al.  Red blood cell transfusion: a clinical practice guideline from the AABB.*Ann Intern Med. 2012 Jul 3;157(1):49-58.
5. Abdo WF, Heunks LM. Oxygen-induced hypercapnia in COPD: myths and facts. Crit Care. 2012 Oct 29;16(5):323. 
7. Putensen C, Theuerkauf N, Zinserling J et al. Meta-analysis: ventilation strategies and outcomes of the acute respiratory distress syndrome and acute lung injury. Ann Intern Med. 2009 Oct 20;151(8):566-76.
10. Brown JB, Gestring ML, Forsythe RM et al. Systolic Blood PRessure Criteria in the National Trauma Triage Protocol for Geriatric Trauma: 110 is the new 90.  Oral Abstracts, AAST July 2014.
11. Eastridge BJ, Salinas J, McManus JG, et al. Hypotension begins at 110 mm Hg: redefining “hypotension” with data. J Trauma. 2007;63(2):291–7; discussion 297–9.
12. Oyetunji TA, Chang DC, Crompton JG, et al. Redefining hypotension in the elderly: normotension is not reassuringArch Surg. 2011;146(7):865–9.
13. Trowbridge RL, Rutkowski NK, Shojania KG. Does This Patient Have Acute Cholecystitis? JAMA. 2003;289(1):80–86.
14. Kitabchi AE, Umpierrez GE, Miles JM, Fisher JN. Hyperglycemic crises in adult patients with diabetes. Diabetes Care. 2009;32(7):1335–43. 
15. Lange H, Jäckel R. Usefulness of plasma lactate concentration in the diagnosis of acute abdominal disease. Eur J Surg. 1994;160(6-7):381.
16.  Cohn B.  Does This Patient Have Acute Mesenteric Ischemia?  Ann Emerg Med. 2014 Jan 30

Open to Interpretation: Do Not ______

The Gist:  DNR (Do Not Resuscitate) orders are subject to variable interpretation by providers and patients whereas Physician Orders for Life Sustaining Treatments (POLST) are becoming increasingly common and have more specific, meaningful directives. As critical care providers, we should understand the meanings behind each of these documents, as well as the limitations.  The Annals of Emergency Medicine August 2014 podcast has a fantastic Free Open Access Medical education (FOAM) discussion of DNRs and POLSTs as they pertain to the physician in the Emergency Department (ED).  Despite these helpful aids, nothing replaces discussions with patients and their family members or health care proxies about treatment that is clinically appropriate and congruent with the patient's goals.

The Case:  A 82 y/o male presents to Janus General in respiratory distress, 72% on 4L of oxygen via nasal cannula up to 92% on 15L non-rebreather from the rehab facility where he is recuperating from a fractured tibia.  Previously in excellent health, he has been febrile and confused for the past two days with radiographic and clinical diagnosis of pneumonia and therapy with azithromycin and ceftriaxone at the facility.  Patient has a signed DNR order and an advance directive stating that for an irreversible/terminal condition the patient would not want artificial support.  The health care proxy is unavailable by phone and the patient lacks a clear sensorium but is in respiratory distress, appears septic, and has a chest x-ray with clear infiltrate and interstitial pattern that may indicate early ALI/ARDS.
  • What should happen?  BiPAP?  Morphine? Intubation?  What's this patient's disposition?  At Janus General, the providers in the ED and the inpatient team disagreed about what the patient's course should be, whether or not the condition was "reversible," and what the patient would want in this situation.  
In a recent post I shared a talk on tips for palliative care in the ED setting.  Despite our best efforts in the ED, uncovering documents such as DNRs and advance care directives may obscure the picture more than provide clarity.  I discovered on rotations through critical care units that the presence of a DNR seemed to bias both myself and my colleagues regarding the care of patients that was unrelated to the performance of cardiopulmonary resuscitation.  I believe we acted based on what we felt was clinically appropriate in the patient's situation but upon closer inspection, I think we were occasionally subject to a touch of another form of bias - The DNR bias.

The Do Not Resuscitate (DNR):  A medical order that specifies one not initiate cardiopulmonary resuscitation (CPR) in a patient who has died (pulseless/apneic) [1].
  • Technically, applies to a dead patient.
  • Does not indicate a patient's general wishes for medical care, only their preference regarding initiation of CPR. 
The Problem With The DNR
DNR orders, which technically only speak to a patient's wishes to receive CPR, have variable interpretations amongst healthcare professionals and, likely, patients [2-4].  The issue lies in the word "resuscitate," which may be used to include fluids, antibiotics, vasopressors, advanced means of ventilation or, at the extreme, CPR.
  • The TRIAD II-IV studies surveyed EMS personnel, physicians, and medical students respectively and provided the participants with an advance care directive as well as case scenarios.  The participants then indicated whether a patient was a DNR or full code and the appropriate action.  Both physicians and EMS providers performed poorly and variably, indicating that the directives were not clear [2,4].
DNR orders may mean that patients receive care that differs from their wishes or standard medical practice.  This demonstrates that the DNR bias may exist, even if it's partially a reflection of a patient's general clinical situation.
  • Aspirin is a non-intensive and relatively safe standard intervention in patients with acute myocardial infarction (AMI) (NNT=42, NNH=167). In patients with an AMI, the Worcester Heart Attack study demonstrated a negative association between aspirin administration and those patients with a DNR [5].  Of note, the individuals in this study with a DNR were "sicker," meaning they had comorbidities or other poor prognostic signs such as shock.  Other markers of more aggressive care such as PCI, thrombolytics, and cardiac catheterization, were also reduced in the DNR cohort.  Therefore, it is possible that this association may represent the belief that these patients were not candidates for these interventions independent of their DNR status.
  • The Worcester Heart Failure study also demonstrated that patients with a DNR were less likely to receive any quality assurance intervention than those with no DNR (HR 0.52, adjusted HR 0.63- 0.4-0.99) [7].  This may have been appropriate given the clinical situation of the patients.
But, it's not all about the co-morbidities:
  • Residents in Missouri nursing homes with a DNR were less likely to be hospitalized following a LRTI (OR 0.69; 0.49-0.97).  Compared with the Worcester Heart Attack study, patients with comorbidities were more likely to receive aggressive treatment (hospitalization) than those without a DNR (excluded patients with a Do Not Hospitalize order) [7].  
The Physician Order for Life Sustaining Treatment (POLST)Physician orders, on a standardized form, that are designed to transfer amongst settings, following an individual from home to hospital and nursing home/rehabilitation facilities.  Most states have POLST programs or are in the process of developing them these programs (map of programs) and some have online registries for providers, mitigating issues with located print copies.  Jesus et al give a good rundown of POLSTs in the ED in Annals of Emergency Medicine, August 2014 [8].

These may be more meaningful in the critical setting of the ED as they may indicate a patient's preference for a broad array of clinical conditions encountered.  For example, in Massachusetts, the back portion of the MOLST resembles a sushi menu where individuals can opt to specify whether they would accept non-invasive ventilation, dialysis, artificial hydration or nutrition and, if yes, whether temporarily or permanently.

Issues with POLSTs:
  • Require a physician signature and require either medical literacy or a good deal of physician explanation.  
  • It is possible that only the sickest patients or those with terminal illnesses may be prompted to have a POLST.
  • Components are still open to interpretation by providers as the reversibility or predicted length of therapy are often difficult to determine upon initiation.  
  • The FOAM blog, GeriPal, has an interesting discussion on the semantics prevalent in the POLST.  For example, the connotation of the word "only" following Comfort Measures is not necessary and undermines the intensive work often required for end of life comfort.  The blog offers some suggestions that may surface as POLSTs become increasingly adopted.
1. Dugdale DC. .Do Not Resuscitate Orders."  MedlinePlus Medical Encyclopedia.  
2.  Mirarchi FL, Kalantzis S, Hunter D, McCracken E, Kisiel T. TRIAD II: do living wills have an impact on pre-hospital lifesaving care? J Emerg Med. 2009;36(2):105–15. doi:10.1016/j.jemermed.2008.10.003.
3. Mirarchi FL, Costello E, Puller J, Cooney T, Kottkamp N. TRIAD III: nationwide assessment of living wills and do not resuscitate orders. J Emerg Med. 2012;42(5):511–20. doi:10.1016/j.jemermed.2011.07.015.
4.Mirarchi FL, Ray M, Cooney T.  TRIAD IV: Nationwide Survey of Medical Students' Understanding of Living Wills and DNR OrdersJ Patient Saf. 2014 Feb 27. 
5. Gurwitz JH, Lessard DM, Bedell SE, Gore JM. Do-Not-Resuscitate Orders in Patients Hospitalized With Acute Myocardial Infarction. 2014;164.
6. Chen JLT, Sosnov J, Lessard D, Goldberg RJ. Impact of do-not-resuscitation orders on quality of care performance measures in patients hospitalized with acute heart failure. Am Heart J. 2008;156(1):78–84. doi: 10.1016/j.ahj.2008.01.030.4. 10.1002/jhm.2234
7. Zweig SC, Kruse RL, Binder EF, Szafara KL, Mehr DR. Effect of do-not-resuscitate orders on hospitalization of nursing home residents evaluated for lower respiratory infections. J Am Geriatr Soc. 2004;52(1):51–8. 
8. Jesus JE, Geiderman JM, Venkat A, et al. Physician Orders for Life-Sustaining Treatment and Emergency Medicine: Ethical Considerations, Legal Issues, and Emerging Trends. Ann Emerg Med. 2014;64(2):140–144. doi:10.1016/j.annemergmed.2014.03.014.