For these cases, the authors used a Zonare Z.One PRO device (ZONARE Medical Systems, Inc, Mountain View, CA) with 14 and 20 MHz linear probes set to the “superficial” or “skin” preset. The US exam included the affected area as well as contralateral or adjacent normal skin for comparison. The probe was held perpendicular to the skin. Still images and video clips were recorded in 2 orthogonal planes. Images were securely saved to the machine’s database. Consent to share the results was obtained from the patients’ parents.
Case 1. The patient was a baby boy of 29-weeks’ gestation born via emergent cesarean delivery due to maternal preeclampsia and pulmonary edema. The mother was 39 years old with a history of gestational hypertension treated with labetalol. All prenatal labs were negative with unknown Group B streptococcus status. The mother received betamethasone, magnesium, and antibiotics before delivery. Apgar scores were 8 and 9. Shortly after delivery, the baby developed mild respiratory distress that was managed with continuous positive airway pressure (CPAP). His chest x-ray was consistent with mild respiratory distress syndrome. Ampicillin and gentamicin were started after the blood culture was drawn. An umbilical venous catheter was placed on day 1 and total parenteral nutrition was initiated. Antibiotics were stopped after 2 days due to normal labs, stable clinical status, and negative blood culture. The baby remained stable on nasal CPAP with nasogastric feeds advancing as expected. The central line was removed on day 7 when the baby achieved an enteral feeding of 100 cc/kg/day. A peripheral intravenous line (PIV) was placed on day 8 for 4 more days for administration of additional IV fluid.
On day 14, baby’s physical exam showed warm, painful, red, and indurated right forearm skin around the area where the PIV was placed (see Figure 2). Blood samples were obtained for complete blood count and culture, and the infant was started on vancomycin and amikacin. The erythematous, swollen area was marked and POC-US was performed on the affected forearm. US showed edematous skin, tissue plane disarray, and hyperechogenicity. No abscess was appreciated (see Figure 3). Further, the white blood cell count was abnormal with significant left shift. Early cellulitis was diagnosed. The baby was continued on antibiotics for 7 days until complete resolution of infection. At the end of his antibiotic therapy, he had a follow-up POC-US exam that showed complete resolution of all signs of inflammation.
Case 2. A 7-year-old boy with global developmental delay, seizure disorder, central apnea, and severe asthma presented to the emergency room after having a febrile seizure and worsening severe respiratory distress that required increases in bilevel positive airway pressure (BiPAP) settings, respiratory medications, magnesium sulfate, and systemic steroids. His extensive medical history included recurrent respiratory infections, multiple intubations, subglottic stenosis, multiple medications, and BiPAP at night. His respiratory viral panel was positive for rhinovirus/enterovirus and coronavirus. He was admitted to the pediatric intensive care unit (PICU), where he was intubated and placed on high-frequency oscillatory ventilation. Due to the possibility of superimposed pneumonia, he was placed on broad antibiotic coverage for 10 days. During his initial PICU stay, he developed hypotension that was treated with multiple fluid boluses and vasopressors. A peripheral arterial line was placed in his right radial artery to facilitate blood pressure monitoring. A PIV was placed in his right wrist vein. On day 7, the PIV was removed due to a suspected grade 4 extravasation, followed by removal of the arterial line. Overlying skin and soft tissue presented with marked blistering, swelling, and erythema. Plastic and vascular surgery evaluated the lesion and recommended elevation and local antimicrobial ointment. Mupirocin was started. A US Doppler scan of the affected area did not show signs of deep venous thrombosis. Over the next week, a few of the blisters ruptured, leaving a partial-thickness wound with irregular edges, periwound erythema, and skin slough covering 40% of the wound bed. Wound care physicians changed management to topical medical-grade Manuka honey (Leptospermum honey), covered by a silicone dressing. Wound healing proceeded as expected.
One (1) week into the treatment, the wound area became increasingly painful, erythematous, warm, and indurated. A clindamycin IV was started and changed to vancomycin IV as per infection disease service recommendation. To ensure no underlying abscess was present, POC-US was performed. The US exam included 3 areas around the wound: the transitional area between normal skin and erythema edge, an area directly over the erythema, and an area at the edge of the wound (see Figure 4). The transitional area showed minimal tissue swelling (see Figure 5). The area over the erythema showed the typical US cobblestone appearance of cellulitis with marked dermal swelling (see Figure 6). Finally, the area at the edge of the wound showed cellulitic changes as well as some deeper tissue planes destruction, with coagulated blood noticeably present (see Figure 7). During the following week, the patient had daily wound exams and POC-US evaluations of the wound area. Medical grade honey was used to help with the wound healing. The patient was discharged home after completing 7 days of IV vancomycin. His wound healed completely 2 weeks after the discharge.