c. A decision will need to be made whether to leave the

cannula in place for any length of time or to remove

it once the pericardium has been drained. This decision will vary in individual cases, but factors to consider include the likelihood of reaccumulation and

Fig. 39.4. Insertion of needle/cannula attached to three-way

stopcock, in the subxiphoid space, directed toward the left

shoulder.

276 Section VII ■ Tube Replacement

the need for repeat drainage versus the risk of infection or entry of free air with an indwelling cannula.

d. In certain cases, the operator may elect to evacuate

the pericardial space directly through the needle,

rather than placing a cannula.

J. Special Circumstances

1. If ultrasound imaging is available, it may be helpful in

planning the needle entry site and angle, as well as

anticipating the distance required to reach the pericardial space (2,15,17,20,21).

2. If transillumination is positive for free air before the

procedure, it can be used to assess the adequacy of air

evacuation after the procedure and to look for evidence

of reaccumulation. Because pneumothorax and pneumomediastinum are potential complications, the availability of transillumination may also be helpful after the

procedure. Transillumination is not a reliable method

to rule out free air or to distinguish between pericardial

air and mediastinal air (5,6).

3. On initial aspiration of the pericardium, air, serous

fluid, serosanguineous or grossly bloody fluid, or fluid

resembling infusate from a central line (including

parenteral feeding fluids) (8,11) may be encountered.

Bloody fluid raises the concern that the needle may

have entered the heart. The following may be helpful

in distinguishing between pericardial fluid and intracardiac blood.

a. In an infant with tamponade, aspirating 10 mL of

blood from the heart will have minimal effect on the

acute hemodynamics, whereas draining as little as

5 to 15 mL from the pericardial space can result

in significant hemodynamic improvement within

30 seconds.

b. If ultrasound is being used, the pericardial fluid volume will appear to be decreased if the needle is correctly positioned. In some cases, one can reliably

identify the needle in the pericardial space (Fig.

39.5) (15).

c. Placing a few drops on a gauze swab may help distinguish the two sources, because serosanguineous

fluid will separate into a central dark red zone and a

more serous peripheral zone, but this can take several minutes.

d. Alternatively, a spun hematocrit can be performed

rapidly if the unit has a readily available centrifuge;

this also takes a few minutes.

RA

RV

LV

LA

Tip of pericardiocentesis needle,

with effusion partially drained and

right ventricle better expanded.

C

Pericardiocentesis needle

entering pericardial space

B

RV

* - Pericardial effusion, RV - right ventricle,

LV - left ventricle

LV

A

Fig. 39.5. Echocardiogram images of pericardiocentesis.

A: Echocardiogram image of pericardial effusion. B: Tip of

needle in pericardial space. C: Pericardial effusion partially

drained.