Ultrasound for Critical Care Physicians: Ghost in the Machine

Ross Davidson, DO

Michel Boivin, MD 

Division of Pulmonary, Critical Care and Sleep Medicine

University of New Mexico School of Medicine

Albuquerque, NM USA

A 53-year-old woman presented to the emergency department after a sudden cardiac arrest at home. The patient had a history of asthma and tracheal stenosis and had progressive shortness of breath over the previous days. The patient’s family noticed a “thump” sound from the patient’s room, and found her apneic. They called 911 and began cardiopulmonary resuscitation. Paramedics arrived on the scene, found an initial rhythm of pulseless electrical activity. The patient eventually achieved return of spontaneous circulation and was transported to the hospital. On arrival the patient was in normal sinus rhythm, with a heart rate of 110 beats per minute. Blood pressure was 80/45 mmHg, on an epinephrine infusion. The patient was afebrile, endotracheally intubated, unresponsive and ventilated at 30 breaths per minute. An initial chest radiograph was compatible with aspiration pneumonitis and a small pneumothorax. Initial electrocardiogram on arrival had 1mm ST-segment depressions in leads V4 to V6. Transthoracic echocardiography was unsuccessful due to patient’s habitus and mechanical ventilation. Because of the patient’s hemodynamic instability and unknown cause of cardiac arrest, an urgent trans-esophageal echocardiogram (TEE) was performed (Videos 1-3).

Video 1. Mid-esophageal 4-chamber view of the heart.

Video 2. Upper esophageal long-axis view of the pulmonary artery and short axis view of the ascending aorta.

Video 3. Upper esophageal short axis view of the pulmonary artery with the ascending aorta in long axis. 

Based on the images presented what do you suspect is the etiology of the patient’s cardiac arrest? (Click on the correct answer for an explanation-no penalty for guessing, you can go back and try again)

1. Massive Pulmonary Embolism
2. Myocardial infarction
3. Pericardial Tamponade
4. Unable to determine

Cite as: Davidson R, Boivin M. Ultrasound for critical care physicians: ghost in the machine. Southwest J Pulm Crit Care. 2018;16(2):76-80. doi: https://doi.org/10.13175/swjpcc027-18 PDF 

Ultrasound for Critical Care Physicians: Two’s a Crowd

A 43 year old previously healthy woman was transferred to our hospital with refractory hypoxemia secondary to acute respiratory distress syndrome (ARDS) due to H1N1 influenza. She had presented to the outside hospital one week prior with cough and fevers. Chest radiography and computerized tomography of the chest revealed bilateral airspace opacities due to dependent consolidation and bilateral ground glass opacities. A transthoracic echocardiogram at the time of the patient’s admission was reported as not revealing any significant abnormalities.

At the outside hospital she was placed on mechanical ventilation with low tidal volume, high Positive end-expiratory pressure (20 cm H20), and a Fraction of inspired Oxygen (FiO2) of 1.0. Paralysis was later employed without significant improvement.

Upon arrival to our hospital, patient was severely hypoxemic with partial pressure of oxygen / FiO2  (P/F) ratio of 43. She was paralyzed with cis-atracurium and placed on airway pressure release ventilation (APRV) with the following settings (pressure high 28 cm H2O, pressure low 0 cm H2O, time high 5.5 sec, time low 0.5 sec). The patient remained severely hypoxemic with on oxygen saturation in the high 70 percent range.

A bedside echocardiogram was performed (Figures 1 and 2).

Figure 1. Subcostal long axis echocardiogram.

Figure 2. Subcostal short axis echocardiogram

What abnormality is demonstrated by the short and long axis subcostal views? (Click on the correct answer for an explanation)

1. Acute cor pulmonale likely due to ARDS
2. Acute myocardial infarction
3. Low left-sided ejection fraction
4. Pericardial tamponade

Cite as: Abukhalaf J, Boivin M. Ultrasound for critical care physicians: two's a crowd. Southwest J Pulm Crit Care. 2016 Mar;12(3):104-7. doi: http://dx.doi.org/10.13175/swjpcc028-16 PDF

Ultrasound for Critical Care Physicians: Tiny Bubbles

Kashif Aslam, MD

Michel Boivin, MD

Division of Pulmonary, Critical care and Sleep Medicine

University of New Mexico School of Medicine

Albuquerque, NM

A 59 year old woman with a past medical history significant for stage IV MALT lymphoma (after chemotherapy and in remission) presented from a long term care facility for respiratory distress and altered mental status. The patient was in hypercarbic respiratory failure with a severe lactic acidosis. Her blood pressure deteriorated, she was begun on vasopressors and intubated.  Pertinent labs demonstrated a white blood cell count of 0.9 X10⁶ /ml, a hemoglobin of 7.1 g/dl, and a platelet count 66 X10⁶  /ml. The patient was started on Cefepime and Linezolid presumptively for septic shock. Ultrasounds of her thorax were performed (Videos 1 & 2).

Video 1.  Ultrasound of the right thorax in the mid-axillary line. 

 

Video 2.  Ultrasound of the right thorax in the mid-axillary line (slightly more caudad).

What is the best explanation for the ultrasound findings shown above? (Click on the correct answer for an explanation)

1. Large pleural effusion
2. Pneumothorax
3. Consolidation due to pneumonia
4. Ruptured diaphragm
5. Lung abscess

Reference as: Aslam K, Boivin M. Ultrasound for critical care physicians: tiny bubbles. Southwest J Pulm Crit Care. 2015;10(5):216-9. doi: http://dx.doi.org/10.13175/swjpcc067-15 PDF

Physical Examination in the Intensive Care Unit: Opinions of Physicians at Three Teaching Hospitals

Rodrigo Vazquez, MD¹

Cristina Vazquez Guillamet, MD¹

Mohamed Adeel Rishi, MD²

Jorge Florindez, MD⁴

Priya S Dhawan, MD³

Sarah E. Allen, MD¹

Constantine A Manthous, MD⁵

Geoffrey Lighthall MD, PhD⁶

Affiliations: University of New Mexico School of Medicine¹ Albuquerque NM. McNeal Hospital², Berwyn Il. Mayo Clinic Arizona³, Scottsdale AZ. Bridgeport Hospital⁴, Bridgeport CT. Yale School of Medicine⁵, New Haven CT. Stanford University School of Medicine⁶, Stanford CA.

Study Sites: Stanford University Medical Center, Stanford CA. McNeal Hospital, Berwyn Il and Bridgeport Hospital, Bridgeport CT.

Abstract

Purpose: Technological advances in intensive care unit may lead physicians to question or omit portions of the physical exam. Our goal is to assess the opinions of intensive care unit physicians about physical examination in modern day medicine.

Methods: Subjects included physicians on medical intensive care unit teams at one university hospital and two university-affiliated teaching hospitals. Participants responded to an interview divided into two sections: (1) A semi-structured interview including open-ended questions on the management of four critical care scenarios and on the utility of physical exam; (2) Multiple-choice questions about physical exam.

Main Results: The response rate was 100%. A total of 122 individuals, 16(13%) attendings, 24(20%) fellows and 82(67%) residents, responded. Half 61 (50%) considered physical examination to be of limited utility in the intensive care unit. Fifteen percent of answers to the clinical scenarios were reasoned based on physical examination. Most extended the definition of physical examination to include data derived from monitoring 119(97%), life support 121(99%) and bedside imaging devices 112(92%). Residents 45(37%), students 35(29%) and nurses 35(29%) were recognized as the team members who examine patients the most.

Conclusion: Physical examination was considered useful by half of the physicians. Percussion is the least appreciated component. The role of nurses examining patients is recognized. A new definition of physical examination that extends beyond the patient to include monitoring, life support and bedside imaging is proposed to revitalize bedside clinical medicine.

For accompanying editorial click here.

Introduction

Physical examination is one of the mainstays of clinical activities at the bedside. The many maneuvers and signs of the physical exam were developed and described over the last two centuries when most patients presented in advanced states of disease with obvious physical examination findings (1). In the last few decades, advances in fields of imaging, laboratory and bedside monitoring technologies have increased expectations for early and accurate diagnoses, often before physical exam findings become apparent (2).

In Critical Care Units (ICU) patients have severe presentations of diseases, making it likely to encounter diagnostic physical examination findings; however ICUs have easy access to imaging and automated physiologic measurements that may lead physicians to question, or omit portions, of the physical examination.

In this context, we sought the opinions of physicians working in intensive care units about physical examination in modern day medicine.

Material and Methods

The study was divided into two sections. The first is based on mixed methods analysis (qualitative and quantitative) of semi-structured interviews with open-ended questions. The second is based on the quantitative analysis of multiple-choice questions.

Setting

The study was conducted in 2011, in three ICUs in three states.  One of three hospitals (Stanford) was a 32-bed closed medical-surgical unit in a university medical center hospital. The other two hospitals were 16-17 bed closed medical units at university-affiliated community teaching hospitals. All three hospitals had postgraduate residencies in Internal Medicine and Pulmonary and Critical Care Medicine, and were equipped with electronic medical records systems and computer acquisition and storage of bedside data. At the time of the study, Stanford had begun an initiative to increase the use and appreciation of physical examination in its medical school (3). No other confounding variables were apparent. The Investigational Review Boards of each center approved the protocol independently and waived the need for written consent.

Eligible subjects included residents, critical care fellows, and attending physicians on ICU rotations. Investigators approached all candidates for possible participation; subjects were informed that the study would evaluate their approach to diagnosis and treatment of ICU patients but not about its specific focus on physical examination.

Data collection

Demographic data collected included age, gender, type of specialty and subspecialty training, and level of training.

First section

Semi-structured interviews on how four hypothetical ICU clinical vignettes would be managed; questions were chosen by consensus of the authors and responses were open-ended.

Subjects were presented with this introductory statement: “I’m going to present you with four clinical scenarios. I would like you to explain how you would manage these clinical scenarios in real life. This is not an exam. We are just interested in how physicians practice.” The following four case scenarios were then introduced: “You have to manage an Intensive Care Unit patient with: 1) hypoxemia, 2) hypotension, 3) dyspnea and 4) oliguria. What would you do?”

After discussing management of the case scenarios, subjects were then asked: “What’s your opinion about the utility of physical exam in the ICU?”

Second section

Multiple-choice questions were then asked of each subject:

- How frequently do you examine your patients? Answer choices (or options): “Always, sometimes, never”

-Who do you think examines their patients the most? Answer choices: “Attendings, fellows, residents, students or nurses”

 -Which data obtained at the bedside should be included in an updated definition of physical exam in the ICU? Inspection? palpation? percussion? auscultation? venous lines? arterial line data? ventilator data?, bedside ultrasonography? Answer options: “Strongly agree, agree, disagree, strongly disagree”

The interview was pilot tested in six subjects to verify subjects had a clear understanding of the questions. Investigators performing the interviews were the same within each center and were trained prior to subject enrollment. Investigators read the questions in the same order. Subsequent questions were not revealed until the previous question had been answered. Responses were recorded and transcribed.

Analysis

Data analysis used a mixed-methods approach for the first section. The transcriptions were analyzed looking for key actions or ideas around which the rest of the response was organized, we called these “codes”. For example if an individual answered: “I would auscultate the lungs, order an arterial blood gas and a chest radiograph ” the codes would be lung auscultation, arterial blood gas and chest radiograph. After analyzing all the answers we decided to group “codes” into categories and report them as percentages of all the answers provided, four clinical scenarios per each of the 122 participants. For the previous example the categories would include: auscultation, laboratory test and radiology.

Mention of the physical exam was categorized as: a) mentions physical examination (e.g. “ I would examine the patient…”), b) mentions physical examination or the intention to go to the bedside, c) describes a reasoned physical examination (e.g.“ I would auscultate the lungs, if I heard wheezes then I would…”).

Illustrative comments were highlighted. The findings of each interviewer were checked against each other. In case of discrepancy, answers were compared to reach a consensus.

The analysis of the second section was quantitative.

We used the statistical package Stata 11. Chi² was used to compare rates. Factorial logistic regression and logistic regression were used to evaluate categorical and continuous data when appropriate. A p -value of <0.05 was considered significant.

Results

A total of 122 individuals were approached for study participation and all agreed to participate. The subjects included 16 (13%) attendings, 24 (20%) fellows and 82 (67%) residents. The average age was 32 years (range 24-65). There were 79 (65%) males. Most respondents had Internal Medicine training 116 (95%) and had attended medical school in the US 76 (62%).

First section

Clinical scenarios

Categories identified during the responses to the clinical scenarios are summarized in Table 1.

We report mention of the physical exam in three not mutually exclusive categories: a) mentions physical examination (e.g. “ I would examine the patient…”), b) mentions physical examination or the intention to go to the bedside, c) describes a reasoned physical examination (e.g.“ I would auscultate the lungs, if I heard wheezes then I would…”).

Answers to “What’s your opinion about the utility of physical exam in the ICU?” The physical exam was considered to be of “limited utility” by 61(50%) of the respondents. Table 2 includes answers that illustrate opinions for and against the utility of the physical exam.

According to the respondents, the components of the physical exam that remain useful in the intensive care unit are: a) general appearance; b) the neurological exam; c) abdominal exam since there are no adequate monitoring devices; d) anterior auscultation of the chest to detect pneumothoraces, effusions or cardiac murmurs; and e) examination of the skin.

Second section, multiple-choice questions

A. How frequently do you examine your patients?

Figure 1. Histogram with the percentages of each of the possible answers to question: How frequently do you examine your patients?

B. Who do you think examines patients the most? (Figure 2).

Figure 2. Histogram with the percentages for each of the possible answers to question: Who do you think examines patients the most?

C. Which data obtained at the bedside should be included in an updated definition of physical exam in the ICU?

At least 90% of the respondents agreed to include data obtained through inspection 112 (100%), auscultation 118 (97%), data from ventilators 121 (99 %), arterial lines 120 (98%), central lines 118 (97%), and bedside ultrasound 112(92%). Palpation 107(88%) and percussion 79 (65%) did not exceed the 90% threshold.

Besides the intergroup comparisons noted above, there were no statistically significant differences between responses based on level of training, age, gender, location of medical school training or hospital (p>0.05).

Discussion

We report the opinion of 122 physicians with regard to physical examination in the intensive care unit and the way they reported using the physical exam in four hypothetical clinical scenarios. We found that half of the physicians reported they considered physical exam useful, but only 15 percent mentioned physical exam in deducing answers to the clinical scenarios. Percussion was the least appreciated component of the physical exam. There was generalized agreement that the inclusion of data derived from bedside imaging, monitoring, and life support devices into an updated definition of physical examination would be valuable. Nurses and students were recognized as the team members who examined their patients the most. Study participants provided explanations behind their opinions.

The findings that only 50% of the physicians found the standard physical examination to be useful, and that only 15 % mentioned the physical exam in deducing their case scenario answers suggests a low appreciation for the standard physical exam. Available literature on the utility of the physical exam supports our current study findings. In one study the time spent at the bedside during clinical rounds was down to 11% from an historical 75%, with most of the time spent in hallways or conference rooms (4,5). In an ethnographic study, residents felt it was unnecessary to examine their patients in the ICU as long as they had monitoring and a good nurse (6).

Perceptions from patients and the general public support our findings that use of the physical exam is low. In a questionnaire to ambulatory patients, 56 patients perceived 113 omissions in their physician visit, the most common omissions being those related to what they felt were missed portions of the physical examination (7). Mass media has produced the following headlines: Physician revives a dying art: the physical; Is physical exam facing extinction? and Not on the Doctors’ checklist but touch matters (8-10).

Comments by our study participants help explain these findings. Participants had more confidence in the accuracy of data provided by monitoring devices and imaging than in findings of their physical exams.  Some participants mentioned that it was difficult to convince peers to change management based on physical examination findings alone. Participants also reported there was lack of role modeling physicians performing physical exams.

Attending and fellow physicians were perceived as the team members who examine their patients the least; Attending and fellows validated this perception in reporting examining their patients sometimes or never in more than half of the cases.

An alternative explanation for this perception about the senior team members could be related to differences in diagnostic reasoning between trainees and more experienced physicians (11). Students and residents probably relay more in hypothetic deductive reasoning and collect larger amounts of data, including a more detailed physical examination, to reach a diagnosis. As they become more experienced and start working as fellows and attendings the use of short cuts, heuristics, increases and they reach a diagnosis with smaller amounts of data. Time constraints also make them relay in the information relayed by more junior team members.

Whatever the reason for this perception about senior team members may be, it explains, at least in part, the atrophy of physical examination skills during residency training (12), and feeds a downward spiral with graduates that examine their patients less and less.

Residents, nurses and students on the other hand were recognized as the ones who examined their patients the most. This observation expands the role of nurses in the ICU, and if confirmed by others could change the allocation of responsibilities in the multidisciplinary ICU team.

Although until now our discussion portrays the current poor standings of physical examination in the ICU, we also found hope.

Despite the small proportion of participants basing their reasoning on physical examination during the clinical scenarios, most responses included going to the bedside and almost all participants agreed on extending the physical examination beyond the patient to include data derived from monitoring, life support and bedside imaging devices.

Just as Laennec revolutionized bedside diagnosis with the introduction of the stethoscope (13), a new standardized definition of physical examination including these new bedside diagnostic tools, has the potential to greatly enrich clinical medicine and would reflect the practice of modern medicine better (14,15). Critical care medicine is in a privilege position to lead this conceptual change and spread it to other specialties.

Our study has several limitations. First of all, it describes opinions and behaviors in theoretical scenarios and the answers provided may not correlate with true physician practices. The order and choice of the clinical scenarios and questions may have biased the respondents negatively against the physical exam. In support of our results, once the participants learned about the focus of the study one would have expected an attempt to offer better impressions of themselves with an “over reporting” bias towards the physical examination. However, our results pointed in the opposite direction. It does not correlate the use of physical examination to outcomes.

In regards to the composition of the respondents, residents conformed the great majority. Although one could argue that this limits the generalizability of the results, the proportion of residents, fellows and attending physicians mimics that found in the ICU teams at the participating institutions. Our findings may not be generalized to hospitals in areas with limited resources.

Finally its main limitation and at the same time its main virtue is the generation of new questions that will require new studies with direct observation of team practices and their correlation to patient outcomes.

Conclusion

Physical examination was considered useful by half of the physicians. Percussion is the least appreciated component. The role of nurses examining patients is recognized. A new definition of physical examination that extends to include monitoring, life support and bedside imaging is proposed to revitalize bedside clinical medicine.

Conflict of interests: The authors declare that they have no conflict of interest.

References

1. Walker HK, Hall WD, Hurst JW, Walker HK. The origins of the history and physical examination 3rd ed. Boston, MA: Butterworths; 1990.
2. Berenguer J, Bruguera M, Gervas J, et al. The Physician of the Future. El Metge del Futur. Fundacion Educaion Medica, Barcelona, Spain; 2009. Available at: http://www.econ.upf.edu/~ortun/publicacions/MedicoDelFuturo.pdf (accessed 1/6/15).
3. Verghese A, Horwitz RI. In praise of the physical examination. BMJ. 2009;339:b5448. [CrossRef] [PubMed]
4. LaCombe MA. On bedside teaching. Ann Intern Med. 1997;126(3):217-20. [CrossRef] [PubMed]
5. Miller M, Johnson B, Greene HL, Baier M, Nowlin S. An observational study of attending rounds. J Gen Intern Med. 1992;7(6):646-8. [CrossRef] [PubMed]
6. Bosk CL. Forgive and remember: managing medical failure. 2nd ed. Chicago, IL. University of Chicago Press; 2003. [CrossRef]
7. Kravitz RL, Callahan EJ. Patients' perceptions of omitted examinations and tests: A qualitative analysis. J Gen Intern Med. 2000;15(1):38-45. [CrossRef] [PubMed]
8. Knox R. The Fading Art Of The Physical Exam. National Public Radio. 2010. Available at: http://www.npr.org/player/v2/mediaPlayer.html?action=1&t=1&islist=false&id=129931999&m=129984296 (accessed 1/6/15).
9. Ofri D. Not on the doctor's checklist but touch matters. The New York Times. August 2, 2010.
10. Grady D. Physician revives a dying art: the physical. The New York Times. October 11, 2010. Available at: http://www.nytimes.com/2010/10/12/health/12profile.html?pagewanted=all&_r=0 (accessed 1/6/15).
11. Sackett DL, Tugwell P, Guyatt GH. Clinical epidemiology: a basic science for clinical medicine, 2nd ed. Boston: Little, Brown; 1991.
12. Mangione S, Nieman LZ. Cardiac auscultatory skills of internal medicine and family practice trainees. A comparison of diagnostic proficiency. JAMA. 1997;278(9):717-22. [CrossRef] [PubMed]
13. Laennec R. Traite de l’auscultation mediate. Bull Acad Natl Med. 1819;151:393-398.
14. COBATRICE Domain 2: diagnosis: assessment, investigation, monitoring and data interpretation. Available at: http://www.cobatrice.org/Data/ModuleGestionDeContenu/PagesGenerees/en/02-competencies/0B-diagnosis/8.asp (accessed 1/6/15).
15. American Association of Chest Physicians. Critical care ultrasonography. http://www.chestnet.org/Education/Advanced-Clinical-Training/Certificate-of-Completion-Program/Critical-Care-Ultrasonography (accessed 1/6/15).

Reference as: Vazquez R, Vazquez Guillamet C, Adeel Rishi M, Florindez J, Dhawan PS, Allen SE, Manthous CA, Lighthall G.  Physical examination in the intensive care unit: opinions of physicians at three teaching hospitals. Southwest J Pulm Crit Care. 2015;10(1):34-43. doi: http://dx.doi.org/10.13175/swjpcc165-14 PDF

Fat Embolism Syndrome: Improved Diagnosis Through the Use of Bedside Echocardiography

Douglas T. Summerfield, MD

Kelly Cawcutt, MD

Robert Van Demark, MD

Matthew J. Ritter, MD

Departments of Anesthesia and Pulmonary/Critical Care Medicine

Mayo Clinic

Rochester, MN

Case Report

A 77 year old female with a past medical history of dementia, chronic atrial fibrillation requiring anticoagulation, hypertension, biventricular congestive heart failure with a preserved left ventricular ejection fraction, pulmonary hypertension, and chronic obstructive pulmonary disease (COPD) presented to the emergency room after she sustained a ground level fall while sitting in a chair. The patient reportedly fell asleep while sitting at the kitchen table, and subsequently fell to her right side. According to witnesses, she did not strike her head, and there was no observed loss of consciousness. As part of her initial evaluation, at an outside hospital, radiographs of the pelvis, hip, and knee were obtained. These identified a definitive right superior pubic ramus fracture with inferior displacement and a questionable fracture of the right femoral neck. Shortly thereafter, the patient was transferred to our hospital for further management. On exam, the patient had a painful right hip limiting active motion and her right lower extremity was neurovascularly intact without paresthesias or dysesthesias. The remainder of the exam was unremarkable. In the emergency room, a repeat radiograph showed no evidence of a right femur fracture. Later in the evening a CT scan of the pelvis with intravenous contrast showed acute fractures through the right superior and inferior pubic rami with associated hematoma. Multiple tiny bony fragments were noted adjacent to the superior pubic ramus fracture (Figure 1).

Figure 1. CT scan demonstrating acute fractures through the superior and inferior pubic rami with associated hematoma. Multiple tiny bone fragments are adjacent to the superior pubic ramus fracture.

The CT did not show an apparent femur fracture. MRI of the pelvis and hip were ordered to assess for a femoral fracture; however this was not obtained secondary to patient confusion thus no quality diagnostic images were produced. The orthopedic service concluded that surgery was not required for the stable, type 1 lateral compression injury that resulted from the fall.

The patient was admitted to a general medicine floor for non-surgical management which included weight bearing as tolerated as well as therapy with physical medicine and rehabilitation. On admission, her vital signs were stable, including a heart rate of 89, blood pressure of 159/89, respirations of 20, with the exception of her peripheral oxygen saturation which was 89% on room air. Over the next several hospital days, she continued to have low oxygen saturations, began requiring fluid boluses to maintain an adequate mean arterial blood pressure (secondary to systolic blood pressure falling to the 70-80mmHg range intermittently) and she developed acute kidney injury with her creatinine increasing to 4.2 from her baseline of 1.1.  Nephrology was consulted to evaluate the acute kidney injury and their impression was acute renal failure secondary to contrast administration for the initial CT scan, in the setting of chronic spironolactone and furosemide use. The patient’s mental status remained altered, her speech although typically understandable was non-coherent, and she remained bed-bound. Due to her underlying dementia, her baseline mental status was difficult to determine and this combined with her opioids for pain control were felt to contribute to her mental status.

During her first dialysis session, the patient developed hypotension and hypoxemia which necessitated a rapid response call and transfer to the intensive care unit (ICU). The impression at the time of transfer to the ICU was septic shock with multi-organ dysfunction syndrome, presumably from a urinary source. The initial exam by the ICU team demonstrated what was thought to be considerable acute mental status change with agitation and moaning, hypotension, hypoxemia, and continued renal failure. Further review of her hospital course revealed that these changes had slowly been progressing since admission. Stabilization in the ICU included placement of a right internal jugular central venous catheter, blood pressure support with vasopressors, as well as intubation and high level of ventilatory support, including inhaled alprostadil, for severe hypoxemic respiratory failure. In addition, she was also placed on continuous renal replacement therapy.

In order to better assess the patient’s fluid status, the service fellow assessed the vena cava with the bedside ultrasound. While observing the collapsibility of the IVC, small hyperechoic spheres were observed traveling through the IVC proximally towards the right heart. A subcostal window focusing on the right ventricle demonstrated the same hyperechoic spheres whirling within the right ventricle. These same spheres were seen in both the four chamber view (Figure 2), as well as the short axis view and were present for several hours.

Figure 2. Four chambered view revealing right ventricular bowing as well as small hyperechoic spheres present in the right ventricle and atria.

Two hours later, a formal bedside echocardiogram was performed to evaluate the right heart structure and function. The estimated right ventricular systolic pressure was at 70 mm Hg, indicating severe pulmonary hypertension. The right ventricle was enlarged, and there was severe tricuspid regurgitation. Again there continued to be small hyperechoic spheres within her right ventricle as well as her right atria. Per the formal cardiologist reading, these were consistent with fat emboli. Further laboratory evaluation, including the presence of urinary fat, helped confirm the diagnosis of fat emboli syndrome.

Supportive care was continued, but without obvious improvement. After a family care conference, she was transitioned to palliative care and died.

Background

Fat emboli (FE) and fat emboli syndrome (FES) have been described clinically and pathologically since the 1860’s. Early work by Zenker in 1862 first described the pathologic significance of fat embolism with the link of fat to bone marrow release during fractures was discovered by Wagner in 1865. Despite the 150 years since its discovery, the diagnosis of Fat Embolism remains elusive. FE is quite common with the presence of intravascular pulmonary fat seen in greater than 90% of patients with skeletal trauma at autopsy (1). However, the presence of pulmonary fat alone does not necessarily mean the patient will develop FES. In a case series of 51 medical and surgical ICU patients, FE was identified in 28 (51%) of patients, none of whom had classic manifestations of FES (2).

The three major components of FES have classically consisted of the triad of petechial rash, progressive respiratory failure, and neurologic deterioration. The incidence following orthopedic procedures ranges from 0.25% to 35% (3). The wide variation of the reported incidence may in part be due to the fact that FES can affect almost every organ system and the classic symptoms are only present either transiently or in varying degrees, and may not manifest for 12-72 hours after the initial insult (4). The patient we present represents both the lack of the classic triad and the delayed onset of signs and symptoms, illustrating the elusiveness of the diagnosis.

Of the major clinical criteria, the cardio-pulmonary symptoms are the most clinically significant. Symptoms occur in up to 75% of patients with FES and range from mild hypoxemia to ARDS and/or acute cor pulmonale. The timing of symptoms may coincide with manipulation of a fracture, and there have been numerous reports of this occurring intraoperatively with direct visualization of fat emboli seen on trans-esophageal echo (TEE) (5-8).

The classic petechial rash, which was not noted in our patient, is typically seen on the upper anterior torso, oral mucosa, and conjunctiva. It is usually resolved within 24 hours and has been attributed to dermal vessel engorgement, endothelial fragility, and platelet damage all from the release of free fatty acids (9). The clinical manifestation of this “classic” finding varies widely and has been reported in 25-95% of the cases (4, 10).

Neurologic dysfunction can range from headache to seizure and coma and is thought to be secondary to cerebral edema due to multifactorial insults. These neurologic changes are seen in up to 86% of patients, and on MRI produce multiple small, non-confluent hyper intensities that appear within 30 minutes of injury. The number and size correlate to GCS, and subsequently reversal of the lesions is seen during neurologic recovery. (11,12).

Temporary CNS dysfunction usually occurs 24-72 hours after initial injury and acute loss of consciousness immediately post-operatively has been documented. Of note, this loss of consciousness may not be a catastrophic event. In a case report by Nandi et al., a patient with acute loss of consciousness made full neurologic recovery within four hours (13). In the retina, direct evidence of FE and FES manifests as cotton-wool spots and flame-like hemorrhages (1). However these findings are only detected in 50% of patient with FES (14)

FES also affects the hematological system, producing anemia and thrombocytopenia 37% and 67% of the time, respectively (15, 16). Thrombocytopenia is correlated to an increased A-a gradient, which Akhtar et al. noted that some clinicians include this finding in the criteria to diagnose FES (1).

Diagnosis

Given the broad and varying manifestations of FES, others have broadened the criteria. The Lindeque criteria require a femur fracture. The FES Index is a scoring system which includes vitals, radiographic findings, and blood gas results. Weisz and colleagues include laboratory values such as fat macroglobulenemia and serum lipid changes. Miller and colleagues (17) even proposed an autopsy diagnosis using histopathic samples. The most widely used criteria are set forth by Gurd and Wilson and require two out of three major criteria be met, or one major plus four out of five minor criteria. Major criteria include pulmonary symptoms, petechial rash, and neurological symptoms. Minor criteria include pyrexia, tachycardia, jaundice, platelet drop by >50%, elevated ESR, retinal changes, renal dysfunction, presence of urinary or sputum fat, and fat macroglobulinemia (1). Of note, none of the proposed diagnostic criteria include direct visualization of fat emboli via ultrasound or echocardiography (18-22) (Table 1).

Table 1: Gurd's Criteria for Diagnosis of FES

Gurd AR. Fat embolism: an aid to diagnosis. J Bone Joint Surg Br. 1970;52(4):732-7. [PubMed]

Mechanism

Two theories explain the systemic symptoms seen in FES. The mechanical theory describes how intramedullary free fat is released into the venous circulation directly from the fracture site or from increased intramedullary pressure during an orthopedic procedure. The basis for the theory is that the fat particles produce mechanical obstruction. However, not all fat emboli translocated into the circulation are harmful. It is estimated that fat particles larger than 8 μm embolize (23-25). As they accumulate in the lungs, aggregates larger than 20 μm occlude the pulmonary vasculature (26). Particles 7-10 μm particles can cross pulmonary capillary beds to affect the skin, brain, and kidneys. On a larger scale, the embolized free fatty acids produce ischemia and the subsequent release of inflammatory markers (27). The mechanism of this systemic spread beyond the pulmonary capillaries is not well understood. Patients without a patent foramen ovale or proven pulmonary shunt develop FES (28). Interestingly enough, other patients with a large fat emboli burden in the pulmonary microvasculature have not progressed to FES (29). One possible explanation for this may be elevated right-sided pressures force pulmonary fat into systemic circulation (1).

The biochemical theory has also been proposed to explain the systemic organ damage. The mechanism describes that enzymatic degradation of fat particles in the blood stream brings about the release of free fatty acids (FFA) (30, 31). FFA and the toxic intermediaries then cause direct injury on the lung and other organs. The fact that many of the symptoms are seen much later than the initial injury would support the Biochemical Theory. This theory also has an obstructive component to it as it recognizes that large fat particles coalesce to obstruct pulmonary capillary beds (11).

Discussion

Fat emboli syndrome is a rare and difficult clinical diagnosis. Currently there is no diagnostic test for FES and even the reported incidence is quite variable. The wide clinical presentation of FES makes the diagnosis challenge, and classic pulmonary involvement does not always occur (31). Furthermore, the symptoms overlap with other illness such as infection, as it did in this patient who was initially thought to be septic. The delayed onset of symptoms may further confound its identification. Finally, the traditional criteria used to diagnosis FES are variable depending on which source is referenced. Case-in-point is the Lindque criteria which require the presence of a femur fracture. By this requirement the patient presented in this case would not have been diagnosed with FES as she presented with a pelvic fracture.

The patient in this case was likely suffering from undiagnosed FES from the time of her admission. Since it did not present in the classic fashion, her progressive respiratory failure and neurologic deterioration were incorrectly attributed to congestive heart failure and opioid administration.

In this patient, the diagnosis of FE was somewhat unexpected, although it was within the differential. For this case the implementation of bedside ultrasound proved critical to the correct diagnosis and subsequent outcome. Instead of following other possible diagnoses and treatment options such as sepsis in this tachycardic, hypotensive patient, supportive care was employed with the diagnosis of fat embolism in mind.

The use of ultrasound imaging is not well studied for the diagnosis of FES, however it may provide an additional tool for making this difficult diagnosis when the classic triad of rash, cardiopulmonary symptoms, and neurologic changes is not seen or is in doubt. When used to evaluate for cardiogenic causes of acute hypotension, bedside cardiac ultrasound may reveal findings suggestive of FES, as it did in this case.

Review of the literature (5-8) confirms similar echogenic findings from fat emboli as seen by TEE intraoperatively during orthopedic procedures. However, similar spheres can be seen in a number of other instances. Infusion of blood products, such as packed red blood cells, may create similar acoustic images. No blood products had been given to the patient at the time of the bedside ultrasound. Additionally cardiologists have traditionally used agitated saline to look for patent foramen ovale. This and air embolism after placement of a central venous catheter can both produce similar images. In this case the emboli were seen traveling through the inferior vena cava, inferior and distal to the right side of the heart. The right internal jugular catheter would not have showered air emboli to that location, additionally once these were seen circulating in the right ventricle, the first action performed was to ensure all ports on the central line were secure. Given that these hyperechoic spheres were present for hours, air emboli would be less likely to be the underlying etiology. The images were later seen during the formal cardiac echo, and again validated by the cardiologist as being consistent with fat emboli.

To our knowledge this is the first case report of critical care bedside echocardiography (BE), assisting with the diagnosis of fat emboli syndrome. This is in contrast to TEE which has been used to diagnose FE and presumed FES in hemodynamically unstable patients in the operating room (5-8).

BE is attractive as it requires less training than TEE and can be repeated at the bedside as the clinical picture changes. By itself BE cannot differentiate FE from FES, but since the practitioner using it is presumably familiar with the patient’s condition, it can be used to augment the diagnosis when other findings are also suggestive of FE.

It has been suggested that a basic level of expertise in bedside echocardiography can be achieved by the non-cardiologist in as little as 12 hours of didactic and hands-on teaching. Given this amount of training, the novice ultrasonographer should be able to identify severe left or right ventricular failure, pericardial effusions, regional wall motion abnormalities, gross valvular abnormalities, and volume status by assessing the size and collapsibility of the inferior vena cava (32-37). Potentially, based on this case, the list could include FE with FES in the correct clinical context, pending further clinical validation.

In conclusion, this is the first reported case of bedside ultrasonography assisting in the diagnosis of FES in the ICU. The case illustrates the diagnostic challenge of FE and FES and also highlights the potential utility of bedside ultrasonography as a diagnostic tool.

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Reference as: Summerfield DT, Cawcutt K, Van Demark R, Ritter MJ. Fat embolism syndrome: improved diagnosis through the use of bedside echocardiography. Southwest J Pulm Crit Care. 2013;7(4):255-64. doi: http://dx.doi.org/10.13175/swjpcc109-13 PDF