Pediatric Chest Needle Sizing

Tension pneumothorax is a rare but life threating condition. Thankfully, it is even more rare in children, and usually occurs while performing PPV. Between 2022-2023, RPPEO paramedics have only inserted 4 chest needles into patients <18 years old, and 3 of those patients were between 14-16 years old. Thankfully, most paramedics will never encounter a neonatal/pediatric tension pneumothorax in their careers!

Prehospitally, the mainstay treatment is a needle thoracostomy – a potentially lifesaving skill. When it comes to needle size selection in a pediatric patient, the research and answer is unclear. There are no clinical studies, and most research to date is based on expert opinion and non-clinical theoretical imaging studies. There is no expectation for management perfection.

In an adult patient, we should be decompressing the 4th intercostal space anterior axillary line (AAL), or the 2nd intercostal space in the midclavicular line (MCL) as a secondary option. The second intercostal space on the MCL has been the classic location recommended, but growing evidence shows that it is probably the least successful of all locations for a successful needle thoracostomy, frequently not reaching the pleural cavity, hence the recent change.

For background, a 2013 retrospective review of the CT scans of patients found that the average chest wall thickness in the overall cohort was 4.08 cm at the second intercostal space on the midclavicular line and 4.55 cm at the fifth intercostal space on the anterior axillary line. (Injury. 2013;44[9]:1183.) Twenty-nine percent had a chest wall thickness greater than 4.5 cm at the second intercostal space on the midclavicular line, and 45 percent had a chest wall thicker than 4.5 cm at the fifth intercostal space at the anterior axillary line.

Further, a 2016 systematic review comparing anatomic locations in needle thoracostomy found that the mean chest wall thickness was 42.79 mm (95% CI, 38.78-46.81) at the second intercostal space on the midclavicular line, 39.85 mm (95% CI, 28.70-51.00) at the midaxillary line, and 34.33 mm (95% CI, 28.20–40.47) at the anterior axillary line (p=0.08). (Injury. 2016;47[4]:797.) The mean failure rate was 38 percent (95% CI, 24-54) at the second intercostal space on the midclavicular line, 31 percent (95% CI, 10-64) at the midaxillary line, and 13 percent (95% CI, 8-22) at the anterior axillary line (p=0.01). The reported incidence of decompression failure using a traditional 5 cm 14G angiocatheter was very high. A 2015 systematic review found that a catheter length of 6.44 cm would be required to ensure that 95 percent of the patients have a successful needle decompression. (Prehosp Disaster Med. 2015;30[3]:249.), which is why many commercial needs are 8.25 cm (3.25 inches).

When it comes to needle size and length selection, current ATLS guidelines recommend the insertion of a 5 cm (2”) 14-gauge needle for adults. The Provincial Equipment Standards for Ontario Ambulance Services have a similar requirement. These standards don’t account for pediatric habitus. The ATLS still recommends the placement of a 14–18 gauge catheter at the 2nd ICS-MCL (ATLS), and PALS recommends the placement of an 18 or 20 gauge needle at the 2nd ICS MCL, despite a lack of research that has clear recommendations for the needle size in a pediatric patient.

Studies have found that compared to adults, the variation in chest wall thickness in children (<13 year old) is less variable (Mandt), and all commercially available catheters will reach the pleural space. Moreover, the 5 cm recommended needle is more than 2x the chest wall thickness of most children, thus location is probably less important than size. In turn, these authors suggest that “a commercially available 14g or 16g standard-length 3.8 cm (11=2 inch) angiocatheter should be used to access the pleural cavity in children.”

With respect to needle size, there needs to be a balance of risk a needle being too long or too short. Too narrow, and it occludes. Too short and we don’t reach the pleura, too long and we risk iatrogenic injury to intrathoracic structures, vasculature, pulmonary injury, significant hemorrhage or vessel transection, organ injury, and cardiac tamponade, amongst other potential complications. This is even more important in pediatric patients, with much smaller chests.

In pedatrics, the chest wall is thin, and the pleural space can easily be reached with common needles. Compared to adults, intrathoracic structures like the heart, large vessels or the thymus gland are in close proximity to the insertion sites and can therefore be injured during needle decompression (Terboven).

Understanding this risk, Leonhard et al undertook a CT-based study to attempt to determine optimal length and diameter of needle to enable successful decompression and at the same time minimize risk of injury to intrathoracic structures and the intercostal vessels and nerve. They looked at 0-, 5-, and 10-year-olds and this is what they found:

As a takeaway, they recommend that “To reduce the risk of injury to the intercostal vessels and intrathoracic structures we recommend a 22G/ 2.5 cm needle for infants, a 20G/3.2 cm needle for 5-year-old-children and an 18G/4.5cm needle for 10- year-old children. In small infants and newborns, the use of a 24G cannula should be considered….Due to the proximity of the heart to the insertion site, this is of particular importance on the left hemithorax.”

Unfortunately, there isn’t enough research on the pediatric population. While needle size selection is important, the major challenge is preventing further intrathoracic injuries. The smaller the kid, the more deliberate you should be with technique. Even if you don’t have commercial chest needles, the angiocaths you carry will work. Advance slowly, aspirate while advancing, and advance the needle and catheter several millimeters from the point of air aspiration, to ensure the tip of the catheter is also in the pleural space.

Bottom line: The key to safety is proper patient selection (VSA or periarrest with good evidence of tension pneumo) and landmarking. If you landmark properly the length and size of the catheter doesn't matter as much, as there isn't much dangerous to hit (and if they have a true tension pneumothorax the organs are pushed away from the insertion site- emphasizing the importance of accurate diagnosis).

Ultimately, the main objective is to make the pleural space communicate with the outside world to equalize the pressure, and recognize if it has been effective or not (ie reassessment, and if not effective make a second bigger, deeper hole).