【Pediatric Anesthesia】The incidence of nausea and vomiting after pediatric surgery is high, which needs attention!

Autumn has its own gentleness that is neither hot nor cold, in this season you can experience the most drizzling rain and the gentlest wind, of course, you can feel the beauty and heart of the fallen leaves falling on the ground, stepping on them and creaking
.

Postoperative nausea and vomiting is the main cause of dissatisfaction in adult patients after anesthesia and surgery, and the incidence of postoperative vomiting (POV) is even higher
in children than in adults.
It is difficult to diagnose nausea in younger children and is likely to be
underestimated.
Effective management is not only important in terms of humane care, but the length of stay in PACU is largely determined by PONOV
.
After tonsillar adenoidectomy, every vomiting that occurs causes a delay of 28 minutes, which is the main reason for
unexpected hospital admissions after outpatient surgery.

In 2014, the PONOV Management Consensus Guidelines were introduced and used as an evidence-based tool for clinicians, which focus on identifying at-risk patients, what are the risk factors for PONV/POV, recommendations for prevention, and the most effective treatment principles
.
Prophylactic treatment of POV in children usually requires pharmacological intervention, but this can be costly or associated with adverse effects
.
Therefore, the ideal target is those children
who are at particular risk of POV.
Although risk factors are similar in children to those in adults, there are some differences
.
POV is rare in children under 2 years of age, but increases with age

Long and increasing, it does not decrease
until after puberty.
A study in children under 14 years of age pointed out that PONC increased sharply at the age of 3, and the incidence increased at a rate of 0.
2%~0.
8% for each additional year of age
.
There appears to be no sex difference in prepubertal children, but a history of PONOV or motion sickness may be a risk factor
in parents or siblings.
Certain surgical procedures have also been associated with a high incidence of POV in children, such as adenotonsillectomy, orchiopexy, penile surgery, hernia repair, and especially strabismus.

The revised PONM consensus guidelines include a simplified risk score to determine the degree of risk for POV in children, and the degree of risk depends on the number of the following risk factors: (1) surgery time≥ 30 minutes; (2) Age≥ 3 years old; (3) strabismus surgery; (4) Family history of
POV or PONV.
As the number of risk factors increases, so does the risk of POV, with one risk factor representing 10% risk and four risk factors representing 70% risk
.
It is important to note that this risk assessment does not include tonsillectomy (with or without adenoidectomy) as a major risk factor for POV, but many consider tonsillectomy to be an important cause of
morbidity.

After identifying children at risk of POV, the next step is to adopt strategies that reduce underlying risk factors, such as advocating the use of propofol or subhypnotic doses of propofol
in total intravenous anesthesia (TIVA).
Although it has not been proven in the pediatric population, for adults at high risk of PONV, inhalation anesthetics and _N2O are recommended against them, and continuous area blocking techniques
should be used.
Although this approach is rarely used in children, it is critical
to implement multimodal analgesia aimed at reducing the need for opioids.
In addition, the Cochrane database of systematic reviews has disproved the idea that
the use of NSAIDs in tonsillectomy leads to increased postoperative bleeding.
Therefore, the use of NSAIDs after such procedures should be encouraged to reduce the need for
opioids.
Finally, it is actually possible to insist that your child drink water before leaving the room

Can increase the incidence of PONM, but appropriate intraoperative hydration has been shown to reduce its incidence
.

Prophylactic pharmacotherapy can be either monotherapy or a combination, but the recommended prophylactic antiemetics for pediatric patients are 5-HT₃ receptor antagonists such as ondansetron, dolasetron, granisetron, torcisetron, and ramosetron
.
Since the publication of the first guidelines, ondansetron (0.
05~0.
1mg/kg, maximum 4mg) has been approved for children aged 1 month, followed by granisetron (40μg/kg) and tophasetron (0.
1mg/kg) as treatment options
.
Ramosetron reduces the incidence of PONV to 9% in children undergoing strabismus surgery, but it has not been listed as a treatment option
for children.
Because drugs such as 5-HT3 receptor antagonists are more effective than nausea in preventing vomiting, they are currently the first-line prevention
of PONV in children.
However, the latest data on the pharmacokinetics of ondansetron indicate a decrease
in the clearance of the drug in children under 6 months of age.
This is partly due to immaturity of cytochrome P-enzymes, so it is currently recommended that children under 4 months of age should be monitored
more closely after receiving ondansetron.
In addition, 5-HT3 receptor antagonists can prolong the QT interval, and caution should be exercised when using large doses to avoid inducing arrhythmias
.

Other treatments for the prevention of PONOV include dexamethasone (0.
15mg/kg), fluperidol (0.
05~0.
075mg/kg to 1.
25mg), diphenhydramine (0.
5mg/kg).
and perphenazine (0.
07mg/kg).

The revised guidelines reduce the upper dose limit of dexamethasone from 8 mg to 5 mg to reduce concerns about
adverse effects such as hypoglycemia, delayed wound healing, and wound infection.
In addition, dexamethasone has also been associated with tumor lysis syndrome, a potentially fatal metabolic disorder due to the destruction of tumor cells, and the use of dexamethasone may mask indicators used to guide tumor treatment, so its use must be discussed
before administering the drug to newly diagnosed cancer patients.
That said, dexamethasone is a highly effective antiemetic drug, and the timing of administration is a key factor
in successful prevention.
For example, dexamethasone should be used early in anesthesia, while ondansetron has been shown to be more effective
before surgery.

The 2014 consensus guidelines recommend that children with moderate or high risk of POV should receive a combination of 2~3 different classes of prophylactic drugs
.
This differs from the recommendation for adult patients, who recommend that only "high-risk" adults should receive combination therapy
.
The recommended combinations in the revised consensus guidelines for children are ondansetron (0.
05 mg/kg) versus dexamethasone (0.
015 mgkg), ondansetron (0.
1 mg/kg) and fluperidol (0.
015 mg/kg), or torcisetron (0.
1 mg/kg) and dexamethasone (0.
5 mg/kg).

。 All of these combinations require intraoperative administration, and specific medications, doses, and timing of administration need to be communicated during handover in order to treat a variety of flare-ups of PONV/POV
with these data.

Guidelines also give recommendations for PONV/POV that occurs in PACUs or when preventive treatment fails, including that antiemetics should be used from different classes rather than those used for prophylaxis
.
Despite the extrapyramidal adverse effects of haloperidol, it can be used in pediatric patients
who are hospitalized and do not respond to all other treatments.
Because it can cause the QT interval to be prolonged, the FDA issued a "black box" warning
for haloperidol in 2001.
The risk of heart effects of halopereridol is no higher than that of other antiemetic drugs being used in doses prescribed in the United States, but this possibility can still significantly reduce a physician's willingness to
prescribe.
Due to reports of cases of respiratory depression and death from the perioperative combination of promethazine and opioids, the US FDA has also issued a boxed warning against promethazine in children
under 2 years of age.

Recently, the neurokinin-1 receptor antagonist aprepitant has been approved for the treatment of chemotherapy-induced nausea and vomiting
in children older than 12 years.
Although there are no data on children yet, numerous studies have reported
on its use in adults for the preventive treatment of PONV.
Researchers have conducted some studies
on non-drug therapies in children.
Although aromatherapy is effective in adults, studies in children have shown that it does not confer significant clinical benefits
.
Acupuncture has been successfully used to prevent POV in children undergoing strabismus, dental surgery, and tonsillectomy, but others have found that the effectiveness of this technique in children is unclear
.

Due to the variety of options and the fact that the incidence of POV in children is higher than in adults, there is a need for a better understanding of POV in children and age-appropriate treatment to reduce this adverse effect
perioperatively.