IRQ Articles

Feature: Youth meets experience

01-17-2017 12:38

Taking an educated approach to the pediatric patientnRSQvaUhRsidBzdkyI3v_Twitter_Bird2.png

BY SUDHEN B. DESAI, MD, ANNA LILLIS, MD, PhD, RAJA SHAIKH, MBBS, MD, AND Mary Landrigan-Ossar, MD, PhD  WINTER 2017

doctor and child
Most IRs’ clinical practices focus on the care of adults. However, an increasing number of pediatric patients are being referred to IRs for evaluation and possible treatment. In some cases, these patients may not require significant deviation from the normal procedures of the lab (e.g., a 160-pound, 15-year-old). In others, modifications must be made to ensure the safe and effective treatment of these patients (e.g., a 2-kg neonate).

The process begins with reviewing the details of the clinical case and then proceeds with preparation of the team and lab for the patient, obtaining consent, ensuring procedural success and planning for postprocedural care. A thorough review of the risks, benefits and alternatives should be performed prior to proceeding with an interventional procedure when caring for a pediatric patient. Throughout the process it also pays to recall the oft-recited mantra from medical school: “Kids are not just small adults.”

Justification

Clinical indications and patient medical history should be carefully considered before beginning any procedure. Is the procedure necessary? Is it likely to yield the desired clinical information or improve the overall care of the patient at this time? Is there a less invasive option? As with adult patients, it is preferable to avoid performing invasive procedures solely for diagnostic purposes (e.g., angiography) if noninvasive imaging can adequately address the clinical question (e.g., MRA or CTA). This especially holds true for pediatric patients who may require sedation or general anesthesia for procedures that an adult may be able to tolerate with local anesthesia only.

Consent

Once the IR and primary team agree that an interventional procedure is in order, a thorough discussion with the consenting party regarding the benefits, risks, details of the procedure and expectations for recovery will be required, if it has not already been initiated during the workup process.

Adulthood can be defined by biological, cultural, social and legal tenets. It is important to note that states have different legal definitions of who is considered an adult. Upon reaching legal adulthood, a person can by law enter into contracts and serve as their own medical decision-making authority, regardless of age. The IR must understand this distinction, since it will determine the ultimate consenting authority and the focus of procedure-related discussions.

The IR should also make every effort to understand the relationship of the parent(s) or legal guardian(s) with the pediatric patient so it can be brought into context of the consent discussion. Many mature pediatric patients are able to participate actively in the decision-making process, even if they are not legally adults. In such cases, it is appropriate to discuss the procedure with both the mature pediatric patient and his or her legal guardian(s), obtaining consent from the guardian(s) and assent from the patient himself or herself.

Long-term sequelae of the disease, expected procedural outcomes or unanticipated complications should also be discussed within the context of the patient’s expected lifespan (typically longer than that of an adult). This is especially relevant when considering the risks of radiation and contrast, particularly in longer procedures or for those patients who might require multiple procedures.

Sedation and anesthesia

Many children require higher levels of sedation than their adult counterparts to minimize motion, tolerate pain and allow positioning during the procedure. Deep sedation or general anesthesia can also provide children postprocedure amnesia.

Sedation or anesthesia for pediatric patients in IR can be a minefield for both inexperienced and experienced practitioners. The hazards of anesthesia outside the operating room have been well described, and the issues of challenging logistics and potential distance from sources of emergent support apply to sedation as well. Given the well-recognized dangers of sedation, it is prudent to obtain a separate consent for anesthesia administration or explicitly document the discussion of its risks and benefits. The decision as to whether a child may be appropriately sedated by a nurse or nonanesthesiologist physician, or whether referral to an anesthesiologist is required, is based on procedural and patient factors. In general, longer, more-complex procedures and children with greater comorbidities may require care by an anesthesiologist.

Drugs should be dosed in pediatrics on a per-kilo basis, with recognition of the changes in pharmacokinetics and pharmacodynamics that pertain to children, in contrast to adults. Many drug regimens have been described for successful procedural sedation; deeper levels of sedation are more safely administered within the context of a sedation service with training in the prompt recognition and remediation of airway compromise.

Sedation or anesthesia can only be safely provided in a room equipped with emergency equipment and medication in the appropriate sizes/doses, sufficient for full cardiopulmonary resuscitation. It is a regulatory requirement that, once sedation achieves a level deeper than minimal, an appropriately trained practitioner must be responsible only for monitoring the patient and may not be involved with the procedure itself. The sine qua non of sedation is a practice environment that emphasizes safety.

Equipment

ImagingIf the IR has sufficient time to do so, a discussion with product representatives is sure to yield valuable insights regarding their product lines specifically tailored towards pediatric patients. Something as simple as having access to shorter wires can make the difference between failure and success.

In the absence of having time to review and order, most labs will carry devices, catheters, wires, etc. that are designed for adults. Hence, bench modifications of adult-configured devices may be required to match the smaller body habitus of children. These reconfigurations should follow the “least invasive but most effective” dictum. Catheters may be cut to shorter lengths, and the smallest caliber needles/sheaths/catheters are used whenever possible.

These modifications are not without risk and should only be performed if the use of standard equipment prevents successful completion of the procedure. If contemplating treating pediatric patients on a more regular basis, the facility should strongly consider purchasing equipment that is designed for use with pediatric patients.

Radiation

Most interventional radiologists practicing in adult populations concern themselves largely with the deterministic effects of radiation, related to dose and time of exposure at time of procedure. These effects usually manifest as damage to bone marrow, gastrointestinal mucosa or skin.

The stochastic effects (those effects related to exposure to any ionizing radiation regardless of time or dose) are far more concerning in the pediatric population. There is no minimum threshold radiation dose for stochastic effects to occur, and stochastic exposure (primarily related to DNA damage) may not manifest itself for decades.

These issues are of greatest concern specifically in young children with many years of life to manifest stochastic damage. Additionally, pediatric oncology patients may already be exposed to high-dose external beam radiation as part of their treatment protocol, adding to the cumulative dose considerations.

In every decision to perform a radiologic study or interventional procedure, the IR should carefully consider the “as low as reasonably achievable” (ALARA) concept of radiation exposure. This concept is even more critical in pediatric diagnostic imaging and pediatric interventional radiology. The IR must always weight the risk of radiation exposure against the benefits of a given image-guided procedure and make every attempt to use the lowest possible radiation dose.

For purposes of obtaining a clinically acceptable image at an optimized radiation exposure, patient size—not age—is the controlling factor. Aggressive dose-reduction methods include:

  • Limiting fluoroscopy time
  • Low-dose pulse fluoroscopy
  • Coning and filtering to the smallest possible region of interest
  • Maximal utilization of imaging modalities that are non-ionizing, such as ultrasound or magnetic resonance imaging

Given the smaller size of children, most tissues can be reasonably imaged with ultrasound and structures including vessels, malformations or masses may be easily and directly accessed percutaneously. Consider ultrasound-guided direct percutaneous intervention as an option before opting to reach a target location via a distant vascular access. For example, percutaneous ultrasound-guided access can be utilized for treating many pseudoaneurysms or vascular malformations and can replace CT guidance for biopsy of many soft-tissue lesions.

Most centers that routinely treat pediatric patients practice these standards of care. If there is a medical need for a particular IR procedure and other exams or methods of image guidance that do not require ionizing radiation (e.g., ultrasound and MRI) are deemed unsuitable, radiation risk considerations should not unduly influence the physician’s decision to perform the procedure.

However, the principles of “Image Gently,” “Step Lightly,” and “Pause and Pulse” should always be followed. A pulse rate of 3–7 frames/second is adequate to accomplish a study in most pediatric patients.

Other helpful tools include last-image hold, use of postprocessing digital magnification, and fluoroscopy contrast runs performed using the “road map” and “fluoro save” options rather than the conventional higher-radiation digital subtraction mode. With adequate preparation time, the lab can request information or an in-service demo from the manufacturer on how to properly configure the imaging equipment specifically for small patients.

Of specific note, radiation of the pediatric eye or gonads should be actively avoided. One should place a gonadal or larger shield to cover the reproductive organs of the patient whenever possible. The support team plays an important role in periodically alerting the interventional radiologist as to the fluoroscopy time and radiation dose.

Contrast

Contrast is a weight-based medication in children; hence, awareness of contrast administration is essential. The risk of dialysis after receiving contrast significantly increases in patients with estimated GFR < 30 ml/min/1.732. Given the small caliber of the vessels, extravasation of contrast or medication can occur during percutaneous access and may quickly result in discomfort or compartment syndrome. Due in part to these limitations, intervention must be accomplished using less contrast than might be employed in an adult.

Carefully monitored volume of diluted non-ionic contrast should be used to minimize renal toxicity. A restriction of 4–6 ml of contrast per kilogram per procedure is recommended. 50:50 (or greater, depending on patient size) dilution of contrast with saline is frequently used to limit contrast volume. A rigid and continuous recording of the contrast being used during the procedure to include both hand injections and power injector volumes should be done. As with radiation, the team should periodically alert the interventional radiologist to cumulative contrast utilization during the case.

Physiologic responses

Children also differ from adults in physiologic responses to intervention. For example, vasospasm is commonly seen in children, making simple access or further intravascular manipulation more challenging. Gentle massages around vessels, warming the room temperature and judicious use of vasodilators for spasm resolution are some options.

Children also react to fluid imbalances and medications more quickly. Children with cardiac, renal and metabolic diseases need input from respective specialists to prevent significant fluid imbalances intraprocedurally. Therefore, a close monitoring of fluid balance and drug dosages based on weight or body surface area is mandatory; vigilant care on the part of specialized pediatric nurses and a pediatric anesthesia team is invaluable, if available. Avoid unnecessary fluid flushes into the pediatric patient (e.g., to flush a catheter or line), since it may account for a much larger proportion of their fluid intake during a case compared to a larger, adult patient. A weight-based calculation of fluid ins and outs is required for pediatric patients.

In complex situations, it is helpful to discuss with the support team (anesthesiologist, nurses and technologists) regarding patient positioning to optimally achieve the procedural goals. For example, a nephrostomy catheter could be placed with a patient in a decubitus or oblique position rather than having a patient with an immature airway in the prone position for a prolonged period. Conversely, it is also true that smaller patients can be easily flipped from head first to feet first or from supine to prone positions to better target the region of interest as needed.

Conclusion

Care of the pediatric patient is extremely rewarding and, in some contexts (e.g., patients with a chronic condition), these patients will be yours for life. A little bit of diligence and awareness in preparing the team prior to the arrival of these patients will pay off in the long run for all involved.

Additional resources:

Society of Pediatric Interventional Radiology: spir.org

Society of Interventional Radiology pediatric guidelines: bit.ly/2hTKweH

  • Quality improvement guidelines for pediatric gastrostomy and gastrojejunostomy tube placement (2014)
  • Quality improvement guidelines for pediatric abscess and fluid drainage (2012)
  • Developing a clinical pediatric interventional practice: A joint clinical practice guideline from the Society of Interventional Radiology and the Society for Pediatric Radiology (2011)
  • Joint quality improvement guidelines for pediatric arterial access and arteriography: From the Societies of Interventional Radiology and Pediatric Radiology (2010)
[Sidebar Start]

Pediatric example: Points to consider for vascular access

  1. Is there an alternative access plan? Can the patient continue along with peripheral IVs? Is there a justifiable indication for the use of a peripherally inserted central catheter (PICC) or central venous catheter (CVC)?
  2. Does the patient have any co-morbidities (congenital heart defect, anomalous anatomy) that might complicate or extend procedural time or serve as a contraindication to anesthesia?
  3. Is there anomalous anatomy that might affect the expected final position of the tip of the catheter? To avoid thrombus or scar formation in vessels that might be important in the future for surgical conduits/repairs (e.g., complex cardiac surgery), should an alternative access site be considered?
  4. Has the patient had lines previously? Were there any procedural issues? Are there known occlusions or other reasons to expect extended procedure time (and modified anesthesia plan)? Is contrast likely to be needed?
  5. Is this a long-term/chronic issue—
    is a tunneled central line or port a viable option?
  6. What is the anesthetic/sedation plan? Consider anesthesia support in the absence of a pediatric certified (and comfortable) nursing staff.
  7. Who is the consenting authority? Are they familiar with central access or will additional time be needed during consent?
  8. Does the IR suite have an appropriately sized central venous catheter or PICC? Placing a 5 or 6 French double-lumen PICC in a neonate is not an option. 1.9 or 3 French single lumen and 2.6 French double-lumen PICCs are commercially available and considered standard for most small pediatric patients.
  9. Does the child need a double-lumen line or will a single-lumen catheter suffice? In the case of small-bore catheters, double-lumen lines frequently clog due to the extremely small inner diameter of each lumen. Reducing the number of lumens allows for larger inner diameter yet smaller overall catheter size.
  10. How do you plan to position the patient on the angio table? Head or feet first?
  11. Do you have a high-quality ultrasound to allow you to see small vessels?
  12. Consider sitting rather than standing and have a tech scrub to help feed a wire.
  13. One can use a 21 gauge entry needle for access (also available in 4 cm lengths), but a small arm vein might be smaller than the width of the bevel of the tip, making wire advancement difficult. A hypodermic needle (24 gauge with a 0.014 inch wire) or angiocath/IV might be a better option.
  14. Even 1 mL of Lidocaine in a small child can obscure the target vein and induce vasospasm. Consider giving Lidocaine after venous entry, and discuss this with your anesthesia/sedation provider so that they might be able to provide an IV medication to cover for pain until the Lidocaine is given.
  15. Avoid through and through punctures. A small hematoma by volume can obscure a long length of vein in the short arm of a child, hindering further access attempts.
  16. Can your imaging equipment be optimized to reduce radiation exposure? Do you need to review with the manufacturer? At least be familiar with how to adjust frame rates, cone down the field of view and have additive shielding available. Remember to “step lightly.”
  17. Take care with length and passage of wires and catheters, as the atria of children are more prone to rhythm disturbance than those of adults. Hence, stay short rather than long.
  18. Consider securement options in advance. Many pediatric PICC sets come with a securement device. This may be preferable to sutures, given risk of injuring other deep vessels or structures as the subcutaneous tissue is thin.
   

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