ICU Volume 12 - Issue 2 - Summer 2012 - Series

Ultrasonography in Critical Care Medicine: The Warms Approach

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Ultrasonography with a head-to-toe approach has become a comprehensive tool in evaluating critically ill patients from the bedside. In this article, authors propose an innovative approach to critical care ultrasonography, which is simple, fast and transferrable to different anatomical sites.

 

Introduction

In the past decade many authors have emphasised the role of ultrasonography in daily patient assessment (Beaulieu and Marik, 2005a;b), even proposing to replace, rather than accompany, the traditional stethoscope. A particular role for ultrasonography is emerging in the management of emergency room (Gunst et al. 2008) and ICU patients (Kendall et al. 2004), where its advantages are well known, including, but not limited to, the absence of radiation exposure, and cost-effectiveness (Kendall et al. 2007). For the critical care patient, instead of concentrating on a specific anatomical district, ultrasonography seems to evolve in the direction of a totalbody approach (Karabinis et al. 2010).

Critical Care Ultrasonography (CCU) is emerging as a multidisciplinary technique, where morpho-functional information, obtained with imaging in different anatomical districts, is integrated with clinical data in real-time by the intensivist (Bouhemad et al. 2007). Beyond already mentioned advantages, CCU permits 24-hour bedside availability and repeatability (Harding et al. 2011), rapid information accumulation on all anatomical districts, possibility to provide assistance to invasive manoeuvres (Hind et al. 2003; Sustic et al. 2000) and titration of mechanical ventilation (Luecke et al. 2012). 

 

Why is CCU Different? 

In the ICU or emergency department, where CCU is performed, the irregularity of the setting clearly discloses major differences in both patient approach and physician observation compared with those in traditional ultrasonography, performed by the radiologist.

The physical approach to the patient is somewhat unstructured: the physician may prefer not to follow an anatomical order, giving priority to ruling out potentially lifethreatening conditions (Nagdev and Stone, 2011), assessing the function of vital organs (Jambrik et al. 2004), or looking for early signs of organ failure (Corradi et al. 2011). This subversion from the classical head-totoe physical exam recalls that of Advanced Life Support, where priority is given to the identification of clinical situations that might precipitate a patient’s conditions.


CCU is held at a clinical moment where a functional evaluation, rather than anatomical, is needed, since it consists of a problemfocused analysis that gives a multidisciplinary visual. Given the emerging relevance of CCU, the intensivist must focus his/her attention on using such tool appropriately; simple questions must be posed and simple answers sought. The main intent of CCU is to allow early goal-directed therapy.

The approach we are trying to propose is conceptual rather than practical, and the aim is to give the physician a short list of questions to pose each time the probe touches a specific part of the body. The simplicity of the approach we focus on does not want to be reductive and we share the invite of other authors (Vignon et al. 2007) for others to be involved in promoting continuous formation in ultrasonography for intensivists. 

 

The Warms-d Approach 

Authors of this paper want to propose a generic approach that can adapt to different situations, involving disparate anatomical sites. Without pretending to give a universal approach, we suggest a conceptual flow that can help in disentangling complex questions that crowd the physician’s mind once a probe is placed on the patient’s skin.

To promote this fluidity, questions and answers have only one mandatory characteristic: simplicity. Yes/no questions are the most valuable, especially if answers are given in a reasonable timespan. The algorithm that follows focuses on the observation that ultrasonography can rapidly identify water and liquids (black), air (barrier effect), see moving parts and measure distances. This is all related to water, air, movement, size and Doppler.

In the WAMS-D approach, we must begin by asking: Is there liquid (water, blood, urine or other) in our image and, if so, is the position and quantity of such liquid abnormal? Then: Is an air collection hampering ultrasound transmission? Are movements of anatomical parts absent or altered? Are anatomical dimensions altered?

Critical care WAMS ultrasonography can give quick answers in most cases. Doppler gives extra functional information in particular circumstances.

 

Warms-d in a Topographic Approach

The following tables, without claiming to be exhaustive, illustrate some of the possible WAMS-D approach applications grouped per anatomical district, as proposed by various authors. 

Head 

In the head region, precious information can be derived through direct visualisation of the optic nerve and its vascularisation (Rajajee et al. 2011b). Transcranial Doppler, born as a highspecialisation exam, is now increasingly being performed at the bedside by adequately trained intensivists (Munoz- Sanchez et al. 2012).

Thorax 

Concerning the thoracic region, many critical cardiac conditions can be rapidly identified by the intensivist, preceding or, in some cases, substituting the conventional echocardiography performed by the cardiologist (Vignon 2005).

For decades air in the inflated lungs has been considered an impassable obstacle to direct parenchymal visualisation. Despite this, indirect signs have been widely investigated to identify many pulmonary conditions (Stefanidis et al. 2011).

Abdomen 

Abdominal CCU has various applications in the study of the hepatobiliary system, pancreas, spleen and genito-urinary system (Wang and Chen 2007). Important data can be obtained from investigation of abdominal vessels: evaluation of volume (Carr et al. 2007) and cases of thrombosis, stenosis or rupture of aneurysms. Protocols have been proposed, reviewed, criticised and refined for rapid assessment in polytrauma patients.

Limbs

In addition to guiding vascular access, CCU of the limbs can rapidly recognise clots in patients with suspected deep vein thrombosis, and identify gas presence in cases of anaerobic soft tissue infections (Jaovisidha et al. 2012).

 

CCU in Invasive Manoeuvres

In addition to the aforementioned diagnostic possibilities, CCU is consolidating its role in assisting the intensivist in the execution of invasive manoeuvres. Some such techniques are widely implemented, like ultrasound-guidance for placement of central venous catheters (Brusasco et al. 2009), execution of pericardiocentesis (Matthew Fields et al. 2012), thoracentesis (Patel et al. 2012) and paracentesis (Nicolaou et al., 2007). Less common applications of CCU include the confirmation of correct endotracheal tube placement (Hsieh et al. 2004), postpyloric feeding tube placement (Hernandez- Socorro et al. 1996) and ultrasound-guided percutaneous dilatational tracheostomy (Rajajee et al. 2011a). 

 

Concluding Remarks 

Ultrasonography has countless applications in the intensive care unit. The fact that basic concepts are simple does not mean that the technique is necessarily easy. Primarily, we think attention should be paid on continuous training: the ultrasound machine should be taken out of the closet and each intensivist, from the student to the director, should have the opportunity to train on a daily basis.

It is the authors’ opinion that excessive subjectivity in image interpretation is a major limitation at the moment; therefore, we believe that maximum efforts should be made to develop and validate a quantitative approach to ultrasonography, to reduce effects from operator inexperience, to increase resolution and to obtain a reproducible datum.

 
 
 
 
 
 
 

References:

 

Beaulieu, Y. & Marik, P. E. (2005a) "Bedside ultrasonography in the ICU: part 1", Chest, 128 (2) 881-95. 

Bouhemad, B., Brisson, H., Le-Guen, M., Arbelot, C., Lu, Q. & Rouby, J. J. (2011) "Bedside ultrasound assessment of positive end-expiratory pressureinduced lung recruitment", American journal of respiratory and critical care medicine, 183 (3) 341- 7. 

Brusasco, C., Corradi, F., Zattoni, P. L., Launo, C., Leykin, Y. & Palermo, S. (2009) "Ultrasound-guided central venous cannulation in bariatric patients", Obesity surgery, 19 (10) 1365-70. 

Corradi, F., Brusasco, C., Vezzani, A., Palermo, S., Altomonte, F., Moscatelli, P. & Pelosi, P. (2011) "Hemorrhagic shock in polytrauma patients: early detection with renal Doppler resistive index measurements", Radiology, 260 (1) 112-8. 

Gunst, M., Sperry, J., Ghaemmaghami, V., O'keeffe, T., Friese, R. & Frankel, H. (2008) "Bedside echocardiographic assessment for trauma/critical care: the BEAT exam", Journal of the American College of Surgeons, 207 (3) e1-3. 

Jambrik, Z., Gargani, L., Adamicza, A., Kaszaki, J., Varga, A., Forster, T., Boros, M. & Picano, E. (2010) "B-lines quantify the lung water content: a lung ultrasound versus lung gravimetry study in acute lung injury", Ultrasound in medicine & biology, 36 (12) 2004-10. 

Karabinis, A., Fragou, M. & Karakitsos, D. (2010) "Whole-body ultrasound in the intensive care unit: a new role for an aged technique", Journal of critical care, 25 (3) 509-13. 

Luecke, T., Corradi, F. & Pelosi, P. (2012) "Lung imaging for titration of mechanical ventilation", Current opinion in anaesthesiology, 25 (2) 131-40. 

Stefanidis, K., Dimopoulos, S. & Nanas, S. (2011) "Basic principles and current applications of lung ultrasonography in the intensive care unit", Respirology, 16 (2) 249-56. 

Sustic, A., Kovac, D., Zgaljardic, Z., Zupan, Z. & Krstulovic, B. (2000) "Ultrasound-guided percutaneous dilatational tracheostomy: a safe method to avoid cranial misplacement of the tracheostomy tube", Intensive care medicine, 26 (9) 1379-81. 

Vezzani, A., Brusasco, C., Palermo, S., Launo, C., Mergoni, M. & Corradi, F. (2010) "Ultrasound localization of central vein catheter and detection of postprocedural pneumothorax: an alternative to chest radiography", Critical care medicine, 38 (2) 533-8. 

Vignon, P., Dugard, A., Abraham, J., Belcour, D., Gondran, G., Pepino, F., Marin, B., Francois, B. & Gastinne, H. (2007) "Focused training for goal-oriented hand-held echocardiography performed by noncardiologist residents in the intensive care unit", Intensive care medicine, 33 (10) 1795-9. 

Vivier, E., Mekontso Dessap, A., Dimassi, S., Vargas, F., Lyazidi, A., Thille, A. W. & Brochard, L. (2012) "Diaphragm ultrasonography to estimate the work of breathing during non-invasive ventilation", Intensive care medicine, 38 (5) 796-803.



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Ultrasonography with a head-to-toe approach has become a comprehensive tool in evaluating critically ill patients from the bedside. In this article, author

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