Ultrasound-guided diagnostic pericardiocentesis in preterm infants: a case report

Abstract Pericardial effusion (PE) in pediatric population can be asymptomatic or a life-threatening event. Reports on neonates or preterm infants are scarce and generally related to pericardiocentesis of large amounts of PE in emergency situations. We describe a diagnostic pericardiocentesis in a preterm infant with small and loculated pericardial effusion and suspected cardiac mass. We used an ultrasound-guided long-axis in-plane pericardiocentesis technique, with a needle-cannula. The operator obtained a subxiphoid pericardial effusion view with a high frequency linear probe and entered the skin below the tip of the xiphoid process with a 20-gauge closed IV needle-cannula (ViaValve®). The needle was identified in its entirety as it courses through soft tissue up to pericardial sac. The main advantages of this approach are a continuous viewing and angulation of the needle through all planes of the tissue and the use of a small, practical, closed IV needle-cannula with blood control septum to prevent fluid exposure while disconnecting the syringe. This novel approach is easy and safe in neonatal population, for diagnostic or emergency drainages and can be performed at bedside in a neonatal intensive care unit.


Introduction
Pericardial effusion (PE) in infant may occur in several conditions, such as malignant or inflammatory diseases, infections, complications after pediatric cardiac surgery, or from a central venous catheter with leakage of fluids [1][2][3].
Pericardiocentesis in neonates can be done through a needle, small cannula, or drainage catheter [4].
In emergent situations, when PE is moderate to large, a "blind" or echo-guided pericardiocentesis can be safe and easy to do [5,6]. Elective pericardiocentesis is usually performed to elucidate the etiology of the pericardial fluid [7][8][9]. In the latter case, ultrasound-guided pericardiocentesis is a well-accepted technique for drainage of PE using a standard 2-D echocardiographic views or, more recently, using the high frequency linear probe [10].
The procedure in neonates and infants can be difficult, especially if the fluid collection is relatively small or loculated.
Data on pericardiocentesis in children are scarce [7][8][9][10] and usually related to large amounts of PE in emergency situations [4,5] or to insertion of pericardial drainage with standard or high frequency ultrasound guidance.
This is a case of diagnostic pericardiocentesis in a preterm infant with small and loculated pericardial effusion and suspected cardiac mass. The report describes an ultrasound-guided pericardiocentesis technique with a needle-cannula approach and a long-axis in-plane ultrasound-guide.

Case report
A male neonate weighting 2400 grams was born at 33 þ4 weeks of gestation, by emergency cesarean section for fetal hydrothorax, in the absence of labor or premature rupture of membranes. The mother was 34 years, first pregnancy, without comorbidities, normal karyotype, negative culture and serologies even for SARS-CoV2 and normal prenatal ultrasound scans. At 33 weeks and 2 days, the fetal echography performed routinely revealed a hydrotorax. Thus, interruption of pregnancy was recommended. An emergency cesarean section was performed in our hospital. At birth Apgar scores were 8 1 min and 9 5 min and the baby was immediately transferred to the Neonatal Intensive Care Unit. A bedside lung ultrasound was performed, not confirming hydrothorax. Neonatal echocardiography at the same time described a pericardial effusion without signs of cardiac tamponade and observed one small echogenic mass in the right atrium, maximum thickness 8 mm, with widely based adhesion at the free wall (Figure 1(a)). No other functional and structural anomalies were found.
Laboratory tests on blood, nasal and oro-pharynx swabs, excluded infection or inflammation related diagnosis. Cardiac magnetic resonance imaging (CMR), performed to better investigate the cardiac mass, confirmed the presence of abnormal intracardiac formation but did not help in tissue characterization. Examination of the pericardial effusion was necessary. PE was evaluated with a standard low-frequency neonatal cardiac probe (S4-10 probe 3-9 MHz, GE Healthcare Logiq E9). A standard 2-D echocardiographic views were obtained to evaluate the size and location of the PE. The moderate amount of PE and its predominantly infra-lateral localization made the subxiphoid puncture more difficult to approach using a standard sector array probe. After baseline cardiac US examination, the subxiphoid view was obtained with the high frequency linear probe (L8-18i probe 8.0-18 MHz, GE Logiq E9), the apical cardiac notch was visualized, effusion diameter was measured and the ideal pathway for drainage was chosen.
The procedure was performed at bedside with the baby in the supine position, sedated, with vital signs and pulse oximetry monitoring during the procedure. The operator acted the procedure in the following steps. In step 1 operator was placed on the right and ultrasound display on the left of baby. At step 2: the skin was prepared with an appropriate antibacterial agent, and a sterile field was created with sterile drapes with a hole, leaving the subxiphoid area exposed. Ultrasound linear probe was covered with a steril coating as well. At beginning of step 3 operator identified structures with the high frequency linear probe positioned below the tip of the xiphoid process, at the left of the midline (Figure 1(b,c)). The ideal pathway to insert cannula that best avoids trauma to these structures was chosen. Depth of the rectangle on the US screen and focus position, using the high frequency probe, was adjusted so that only the PE and the left ventricle were visible. In step 4 the operator holds the probe in one hand and in the other a 20-gauge closed IV needle-cannula (ViaValveV R ) ( Figure 2) with multi-access blood control septum. With US guide in a long-axis view, the operator entered the skin below the tip of the xiphoid process, at the left of the midline, with cannula at a 30-to 40degree angle to the skin toward the left shoulder. The needle was identified in its entirety as it courses through soft tissue, slowly approaching the pericardial sac. Deflection and ultimately puncture of the pericardial sac could clearly be seen as the needle entered the pericardium (Figure 1(c,d)).
Step 5, after pericardial puncture, the operator then stopped the advancement of the needle and checked for fluid drainage, fixed the needle in position and advanced the cannula over the needle into the pericardial space, removed the needle and connected the cannula to the syringe starting the drainage.

Discussion/conclusion
This is the first report describing a diagnostic pericardiocentesis in a preterm infant using ultrasound-guided long-axis technique, with an intravenous needle-cannula.
There are several data in adults describing echocardiographic-guided percardiocentesis, with a common cardiac probe or with high-frequency ultrasound-guide [6,11,12]; however data in pediatric population usually describe standard echo-guided pericardiocentesis via catheter [5,7,9] and report rare complications like right ventricular entry.
Law et al. [10] introduced the ultrasound-guided long-axis pericardiocentesis via catheter in small children with postoperative pericardial effusion and hemodynamic compromise, with no complications encountered. Pericardiocentesis in newborns and infants can be technically challenging, especially if fluid collection is relatively small or loculated. The standard echocardiographic-guided technique with low-frequency probe assess the size and location of the pericardial effusion but the needle is not consistently displayed in real time as it enters the pericardial space [5,7]. This condition expose to inadvertent entry into a vital structure causing pneumopericardium, pneumothorax, cardiac perforation etc. For these reasons, we have adopted a long-axis imaging technique utilizing an in-plane approach with a linear array US probe which allow a continuous visualization of the needle. In this regard, our group has previously already published a extensive experience in children and neonates with US-realtime guide for vascular access [13][14][15] using long-axis ultrasound imaging technique.
The main advantages of this approach were the following: i) visualization of the surrounding structures avoiding lungs, thoracic vessels and peritoneum; ii) guiding the needle site and angle of entry; iii) continuous visualization of the needle through all planes of the tissue as it enters the fluid collection.
Considering the diagnostic purpose and the small amount of fluid in the pericardial sac we decided against insert a catheter with Seldinger technique. We used a closed IV needle-cannula (ViaValve V R ) with multi-access blood control septum, to preventing fluid exposure while disconnecting the syringe from the catheter hub, risks of contaminations and dislocation.
The use of the ultrasound-guided long-axis technique for pericardiocentesis, with intravenous needlecannula, is easy and safe in neonatal population, for diagnostic or emergency drainages and can be performed at bedside, in a neonatal intensive care unit. Echocardiographic-guided pericardiocentesis is the standard of care when draining pericardial effusion and is an important skill for a clinical neonatologist.
Ultrasound-guided long-axis imaging technique, using intravenous needle-cannula, offers potential advantages in terms of feasibility and safety in neonates, especially for small or difficult pericardial effusions. Specific neonatal simulation training can be useful to improve the mastery of the technique.

Ethical approval
Written informed consent was obtained from the mother for publication of this case report and accompanying images.

Disclosure statement
No potential conflict of interest was reported by the author(s).

Funding
The author(s) reported there is no funding associated with the work featured in this article.