2.3 Hemodynamic Monitoring & Advanced Vascular Access (CVP, Arterial Lines, ScvO2)

Hemodynamic Monitoring & Advanced Vascular Access in Pediatric Critical Care

Clinical core: Obtain reliable access quickly during resuscitation. Choose monitoring to answer a specific clinical question. Compare the pressure or saturation trend with the child's perfusion and check the measurement system before escalating treatment.

Obtain emergency intraosseous access

In pediatric cardiac arrest, 2025 AHA/AAP PALS calls for rapid IV or intraosseous (IO) access. Select the initial route by availability, expertise, and time to access. In a critically ill child with a pulse, use IO access when obtaining an IV is difficult and delay would interfere with resuscitation. Follow neonatal resuscitation guidance for access during resuscitation at birth.

The rigid marrow space contains venous channels that allow emergency vascular delivery. Check site and needle selection against the device instructions. For example, Arrow EZ-IO pediatric landmarks include:

Avoid a fractured target bone, infection at the insertion site, inability to identify landmarks, a site with significant prior orthopedic intervention, or an EZ-IO attempt in the same bone within the past 48 hours. Select a different eligible bone if needed. Confirm position and patency before infusion, secure the catheter, and monitor for infiltration. Flow often requires a pressure bag, pump, or syringe technique per protocol. In an awake child, address infusion pain using the pediatric IO analgesia protocol.

Check the route and preparation for each drug. Exercise particular caution with hypertonic or vesicant agents and obtain suitable ongoing access. If the limb swells, becomes tense, or shows deteriorating distal perfusion, stop infusion and evaluate promptly for extravasation or compartment syndrome. Remove the IO promptly once reliable alternative access is established. Follow the device and institutional dwell limits. The U.S. manufacturer specifies up to 24 hours for EZ-IO, with an extension up to 48 hours for patients aged 12 or older only when alternative IV access is unavailable or unreliable.

Insert and maintain a central venous catheter safely

Select the catheter, lumens, and site for the intended infusion, urgency, expected duration, anatomy, and thrombotic, infectious, and mechanical risks. In septic shock, start an indicated vasoactive infusion through suitable peripheral venous access if waiting for a central line would delay treatment. 2026 pediatric Surviving Sepsis Campaign

The 2025 American Society of Echocardiography guidance supports real-time ultrasound guidance by trained clinicians for pediatric internal jugular and common femoral access when possible. Scan for vessel size, depth, patency, and nearby structures. Compare compression and flow when needed to distinguish vein from artery. Use a sterile probe cover and gel for central access. Track the needle tip and confirm that the wire is in the intended vessel before dilation. Maintain control of the wire, verify catheter tip location before use according to catheter type and local protocol, and assess for complications such as pneumothorax when the approach risks pleural injury.

Use hand hygiene, a cap, mask, sterile gown and gloves, and a full-body sterile drape for central insertion. Use an appropriate skin antiseptic and let it dry. The SHEA acute-care bundle specifies alcoholic chlorhexidine for routine CVC skin preparation. For NICU patients the CDC advises considering alcoholic chlorhexidine when benefits outweigh risks, accounting for gestational age, postnatal age, and skin maturity. Follow the neonatal protocol. Disinfect hubs before access, maintain the dressing, and review line necessity daily. SHEA acute-care recommendations · CDC neonatal recommendations

Interpret central venous pressure and fluid response

A catheter near the superior vena cava–right atrial junction can measure central venous pressure (CVP) as an estimate of right atrial pressure. Check transducer level, zero, waveform, and measurement conditions. Positive-pressure ventilation, abdominal pressure, and right ventricular dysfunction can affect the value. Track comparable measurements and interpret them with cardiac function and clinical perfusion.

Cannon $a$ waves can occur when atrial contraction coincides with a closed tricuspid valve, as in complete heart block. A prominent systolic $c$–$v$ wave can occur with significant tricuspid regurgitation. Match changes to the ECG and clinical context.

An isolated CVP cannot diagnose hypovolemia or predict an increase in stroke volume after fluid. If a small fluid challenge is indicated, assess blood pressure and stroke volume or cardiac output where available, with clinical perfusion and signs of congestion. A rising CVP without improved output or pressure argues against further boluses. Use the disease-specific fluid strategy, including limitations for cardiogenic shock. ESPNIC pediatric monitoring consensus

Place an arterial line and troubleshoot its waveform

An arterial catheter provides beat-to-beat pressure and access for arterial sampling. Use a site suited to the child and the clinical indication. CDC pediatric guidance prefers the radial, dorsalis pedis, or posterior tibial site over femoral or axillary placement for infection prevention and advises against brachial insertion in children. Femoral placement may be necessary in selected cases. Use ultrasound when feasible and document distal perfusion before and after insertion. For radial access, identify a patent segment at the wrist. With sterile preparation, follow the needle tip into the lumen in short- or long-axis view, advance the catheter by the device technique, and confirm an arterial waveform after connecting the transducer. Keep the circuit closed and labeled. Inspect the site and distal limb for bleeding, infection, thrombosis, or ischemia. ASE cannulation guidance · CDC arterial catheter recommendations

Level the transducer to the reference point for the measurement and zero it to atmosphere. Check for a rapid systolic upstroke, systolic peak, a dicrotic notch associated with aortic valve closure, and diastolic runoff. If a waveform looks distorted, reassess the patient, compare with an appropriately sized cuff if possible, and check the circuit. A brief fast-flush test assesses the pressure system's response. Use the device and institutional procedure, including any pediatric flush-volume restrictions.

Mean pressure is often less distorted by damping than systolic and diastolic values. A leveling or zeroing error can shift the entire pressure tracing. A transducer below its reference point reads high. Recheck after moving the patient or the transducer. Arterial pressure system dynamic response

Pulse pressure variation (PPV) expresses the difference between maximum and minimum pulse pressure over the respiratory cycle relative to their mean. For a maximum of 32 and minimum of 28 mmHg, the calculation is $(32-28)/30 \times 100 \approx 13.3\%$. The result alone does not establish fluid responsiveness in a child. Spontaneous effort, rhythm, ventilator settings, and thoracic conditions influence respiratory variation. Doppler variation in aortic peak velocity has supporting pediatric data in selected mechanically ventilated children. Use it with the child's other hemodynamic findings. Pediatric comparative study · ESPNIC monitoring consensus

Central venous oxygen saturation and resuscitation

Central venous oxygen saturation ($ScvO_2$) measured from a central catheter with its tip near the right atrium reflects oxygen remaining in the venous blood sampled. Pulmonary artery blood provides true mixed venous oxygen saturation ($SvO_2$), which includes venous return from more regions. The central sample helps assess oxygen delivery relative to consumption but is not interchangeable with the mixed sample.

Systemic oxygen extraction is the difference between arterial and mixed venous oxygen content divided by arterial oxygen content. Neglecting dissolved oxygen and using a central sample gives a bedside approximation, $(SaO_2-ScvO_2)/SaO_2$. At $SaO_2=99\%$ and $ScvO_2=54\%$, this yields $45/99\approx45.5\%$. The estimate cannot identify which component is driving the difference.

In pediatric septic shock, the 2026 Surviving Sepsis Campaign conditionally suggests targeting $ScvO_2\ge70\%$ when central venous access is available. Interpret a low or falling value with exam findings, sampling site, lactate trend, ventricular function, hemoglobin, oxygenation, and metabolic demand. Reassess fluid tolerance before giving more volume. A high reading can accompany reduced oxygen use or abnormal distribution of blood flow and does not establish that tissue perfusion is adequate.

Treat the identified contributors to poor perfusion. A single saturation value does not establish a hemoglobin target or mandate transfusion. Pediatric TAXI recommendations give no fixed hemoglobin threshold for unstable nonhemorrhagic shock and recommend against red cell transfusion at hemoglobin at least $7\text{ g/dL}$ in hemodynamically stabilized children with severe sepsis or septic shock.