Ultrasound in the Surgical Intensive Care Unit

Ultrasound in the Surgical Intensive Care Unit

uids. These collections are usually anechoic. Their observation alone is usually sufficient for diagno- sis. The increase in volume of a collection is one criterion for reoperation in postoperative peritoni- tis [4]. We simplify the approach by adopting the easy tap policy. At the expense of useless taps (but never deleterious if basic rules are respected), sep- tic or hemorrhagic postoperative complications will be promptly detected.

The classic subphrenic abscess is rare in our observations.

Acute acalculous cholecystitis is probably a complication particular to the surgical ICU.

Forgotten foreign bodies will easily be detected.

A compress gives a large image with a matrix-like pattern and a massive acoustic shadow. A metallic instrument has a strikingly straight shape, with typical posterior artifacts we call S lines.

Hematomas are first anechoic, then rapidly become echo-rich and yield heterogeneous, solid images. They can be observed in the retroperi- toneum, the pelvis, and the rectus abdominis muscle.

An »echological« distinction between medical and surgical patients should not make sense per se, but some differences can be underlined.

General Issues

The surgical patient is often surrounded by a bar- rage of acoustic barriers: wounds, dressings, ortho- pedic material, cervical collar. This may limit the use of ultrasound, but these obstacles can be over- come. The problems of asepsis are more important than in the medical setting, and vigilance regarding crossed infections must be reinforced.

The Abdomen

Dressings sometimes cover the entire abdominal wall, but these limitations can be bypassed. The dressings can be withdrawn, the probe can be in- serted in sterile conditions, a sterile contact prod- uct can be used, although these procedures may seem overly restrictive. The sterile protection of the probe should conduct the ultrasound beam with- out interference [1]. Fine transparent adhesive dressings such as OpSite and Tegaderm offer the advantage of being transparent to ultrasound.

Their use should therefore be encouraged. Some thick dressings may appear impenetrable by ultra- sound, but we have noted that ultrasound beams occasionally are not stopped, and basic answers to clinical questions can be obtained. In addition, medical personnel should be taught to wisely apply dressings, since critically ill postoperative patients will unavoidably have ultrasound examinations.

Apart from the anomalies described in earlier chapters, ultrasound can search for infected post- operative collections [2] (Fig. 23.1). For some authors, ultrasound sensitivity is high, whereas specificity is low [3]. It is true that noninfected col- lections are most often encountered in this setting, such as serous, lymph, urine, bile or digestive liq- CHAPTER 23

Fig. 23.1. Intra-abdominal abscess in a man operated on for colic ischemia. Transverse scan of the right fossa iliaca. The ultrasound-guided tap was particularly rele- vant here

Postoperative Abdominal Interventional Ultrasound

A simple tap will confirm infected collections. Per- cutaneous drainage under ultrasound guidance deserves to be subsequently tried. The fluidity helps in choosing the appropriate caliper of the material [5]. This kind of procedure can preclude subsequent surgery, which has higher morbidity and mortality rates. This is the best procedure for some [6], who reserve conventional surgery for complex cases, or when a percutaneous route appears dangerous (bowel obstacles, for instance).

Before inserting a large drain, it can be advanta- geous to withdraw the maximum amount of pus with a fine needle, which will in certain cases be considered sufficient.

Postoperative Thoracic Ultrasound

Hemothorax, pneumothorax, tamponade, phrenic paralysis, pneumomediastinum, some false aneu- rysms (see Chap. 19) and sometimes mediastinitis are accessible with ultrasound.

In the postoperative thoracic period, the inten- sivist must promptly determine if the content of the hemithorax is fluid or air. Ultrasound immedi- ately provides the answer.

A periaortic collection can be detected and even tapped with ultrasound guidance. Sepsis of the prosthesis will thus sometimes be diagnosed. In this severe setting, the current habit is, however, to perform CT, despite its invasiveness.

Here again, appropriate information to the team limits the extent of the dressings.

Thromboembolic Disorders

Ultrasound is more laborious in surgical patients than in medical patients, especially trauma patients, as the dressings, surgical devices, pain and post- contusion changes can decrease the potential of ultrasound. Deep venous thrombosis, however, seems more frequent in the surgical ICU, perhaps because local trauma is a major cause for venous thrombosis. It must be remembered that compres- sion ultrasound can be painful, and Doppler may have an interest here.

Upper Extremity Veins

A frequent problem in the emergency setting is the difficulty of inserting a central venous catheter. In surgical ICUs, patients have already been man- aged. Hypovolemia has been corrected. Therefore, problems in inserting venous lines may not be as critical as in the medical ICU.

In our experience, the frequency of internal jugular venous thrombosis seems extremely high in severely ill surgical ICU patients (Fig. 23.2, and see Figs. 12.6, 12.9, 12.10, 12.13, pp 72–74). Indepen- dent factors may explain this, such as the possibly more frequent use of cardiac catheterization in certain surgical ICUs.

References

1. Kox W, Boultbee J (1988) Abdominal ultrasound in intensive care. In: Kox W, Boultbee J, Donaldson R (eds) Imaging and labelling techniques in the criti- cally ill. Springer-Verlag, London, pp 127–135 2. Weill FS (1989) Echographie abdominale du post-

opéré. In: Weill FS (ed) L’ultrasonographie en patho- logie digestive. Vigot, Paris, pp 536–544

3. Mueller PR, Simeone JF (1983) Intra-abdominal abs- cesses: diagnostic by sonography and computerized tomography. Radiol Clin North Am 21:425–431 4. Dazza FE (1985) Péritonites graves en réanimation:

modalités du traitement chirurgical. In: Réanima- tion et médecine d’urgence. Expansion Scientifique Française, Paris, pp 271–286

5. Van Sonnenberg E, Mueller PR, Ferrucci JT (1984) Percutaneous drainage of 250 abdominal abscesses and fluid collections. Radiology 151:337–347 6. Pruett TL, Simmons RL (1988) Status of percuta-

neous catheter drainage of abscesses. Surg Clin North Am 68:89

164 Chapter 23 Ultrasound in the Surgical Intensive Care Unit

Fig. 23.2. Massive thrombosis of the left internal jugular vein in a patient who underwent venous catheterization.

Note that this thrombosis is completely occlusive and extends at least 6 cm in the craniocaudal axis