Advances in clinical research on postoperative gastrointestinal disorders

Authors: Li Yue, Feng Yi, Yan Qi, Department of Anesthesiology, Peking University People's Hospital

Many patients will undergo a process of recovery of gastrointestinal function after surgery, especially after abdominal surgery, that is, post operative gastrointestinal dysfunction (POGD)

1.

The I-FEED (intake, feeling nauseated, emesis, physical exam, and duration of symptoms, I-FEED) scoring system can be used to evaluate the severity of patients with different degrees of postoperative gastrointestinal discomfort, which basically covers all possible postoperative gastrointestinal function states

Patients with a total score of 3 to 5 are defined as post operative gastrointestinal intolerance (POGI), typically characterized by the absence of initial digestive symptoms after surgery, but nausea, small amounts of bile-free vomit, and bloating after 2 days

Patients with a total score of ≥6 are defined as postoperative gastrointestinal dysfunction, such patients have manifestations of intestinal obstruction, abdominal percussion can be heard with obvious drum sounds, nausea symptoms can not be relieved by drugs, vomiting is large and contains bile, completely unable to eat by mouth, need parenteral nutrition and the placement of a gastric tube to prevent aspiration

The I-FEED scoring system defines the most symptomatic as postoperative gastrointestinal dysfunction, and this article describes postoperative gastrointestinal dysfunction in a broader sense, encompassing all pathological states

2.

POGD is the result of intestinal inflammatory response and neuroendocrine regulation jointly inhibiting gastrointestinal function, and is a gastrointestinal coordination movement disorder

Inflammatory response: The intestine is one of the body's larger immune organs and belongs to the inherent immune system

The squeezing and pulling of the intestinal tract by surgical operations, the mechanical stimulation of the abdominal drainage tube after surgery, ischemia and hypoxia, etc.

Inflammatory factors have a direct inhibitory effect

Neuroendocrine regulation: the normal activity of the gastrointestinal tract is mainly innervated

After the activation of the sympathetic nerve, the vagus nerve can be inhibited by the release of visceral nerves or external monectoid nitrogen oxide to achieve the purpose of inhibiting gastrointestinal function, and may also generate pro-inflammatory factors in the process of neural reflexes to cause nerve inflammation

The interstitial cell of cajal (ICC) forms a continuous network of cells through the intestinal wall that can generate and propagate slow waves that depolarize

In addition, opioids can bind to opioid receptors distributed on presynaptic neurons in the muscular layer of the intestine, resulting in a decrease in intestinal peristalsis waves, cessation of movement, and gastrointestinal reactions

3.

Accelerated rehabilitation after surgery (ERAS) can reduce the patient's perioperative stress response and promote early recovery
of organ function.
Combined with the ERAS concept, POGD prevention is carried out throughout the perioperative period
.

Preoperative preparation: postoperative nausea and vomiting (postoperativenauseaandvomiting, PONV) is an important factor
in causing POGD.
Females, non-smoking, history of motion sickness, and opioid use are risk factors for the development of PONV, and antiemetic antiemetics
should be routinely used preoperatively.

Mechanical bowel preparation (MBP) refers to the oral laxative, retrograde enema, and diet regulation applied to the preoperative period, and has long been a routine part
of the preparation for major surgery such as gastrointestinal malignancies.
MBP combined with oral antibiotics (OAB) significantly reduces the incidence of POGD, possibly because MBP-OAB reduces the incidence
of secondary POGD by reducing postoperative anastomotic fistula and intra-abdominal infection.

The routine use of gastric tube before open surgery increases the occurrence of complications such as pneumonia, atelectasis, fever, and prolonged postoperative recovery time for oral feeding, which prolongs the recovery time
of patients after surgery.
Although patients who do not use a gastric tube experience more symptoms of digestive discomfort such as bloating and nausea and vomiting, the recovery time to gastrointestinal function after surgery is shortened and the incidence of pulmonary complications is also reduced
.
Therefore, routine use of gastric tubes
is not recommended.
However, for high-risk patients with obvious gastric wall edema, severe abdominal adhesions, and severe obstruction, in order to avoid a large number of aspirations, surgeons should treat it with caution and decide whether to use a gastric tube
in combination with clinical experience.

Acupuncture has a certain regulatory effect
on gastrointestinal function.
Zhang Ke et al.
have shown that transcutaneous electrical acupoint stimulation (TEAS) in patients with laparoscopic non-gastrointestinal surgery 30 minutes before surgery to the end of surgery, the first exhaust and defecation time of postoperative patients is significantly shortened, the incidence of postoperative nausea and vomiting is reduced, and the plasma motilin and gastrin levels measured 12 hours after surgery are increased
。 Wang Qun and other studies have shown that needle stimulation of bilateral foot Sanli acupoint and internal guan acupuncture can significantly reduce the incidence of nausea and vomiting after laparoscopic cholecystectomy, and can effectively promote the recovery
of gastrointestinal function after surgery.

Intraoperative management: high chest epidural anesthesia can reduce the production
of postoperative bowel paralysis by inhibiting nerve reflexes and improving blood flow to the internal organs.
Epidural anesthesia in the thoracic segment had a smaller effect on gastrointestinal function than general anesthesia, and the recovery time of patients with gastrointestinal tract after surgery was significantly shortened
.
The inhibitory effect of opioids on gastrointestinal function is clear
.
Exogenous opioid analgesics, as well as endogenous opioids produced by surgical stress, inhibit gastrointestinal function
.
Reducing the use of opioids can significantly shorten the recovery time
of postoperative gastrointestinal function.
Therefore, multimodal analgesia is recommended to minimize opioid use
.
Regional nerve blocks, lidocaine infusions, nonsteroidal anti-inflammatory drugs, gabapentin, and ketamine can all be used to replace opioids for satisfactory analgesic effects
.

Abdominal exposure due to open surgery may be an important factor
in postoperative gastrointestinal recovery.
Tan and other studies have shown that abdominal exposure can lead to intestinal mucosal barrier and intestinal motility dysfunction, and this injury is clearly positively correlated with the time of exposure, and a short period of abdominal exposure may cause a systemic inflammatory response
.
Intra-abdominal surgical procedures are another factor
affecting postoperative gastrointestinal recovery.
The operation of the gastrointestinal tract during surgery can not only initiate the inflammatory response of the gastrointestinal tract, but also activate the neuroendocrine reflex mechanism, resulting in the occurrence
of POGD.

Even with open surgery, minimizing the trauma of the surgery is conducive to the recovery
of gastrointestinal function after surgery.
The tissue damage caused by laparoscopic surgery is small, the inflammatory response is light, the bleeding is small, and the patient's gastrointestinal function recovers quickly after surgery, which can significantly reduce the occurrence of POGD and shorten the hospital stay
.
It is important
to maintain a steady state of the internal environment.
In contrast, excessive rehydration can cause intestinal wall edema, destroy tissue oxidation, and insufficient rehydration lead to insufficient perfusion, compared with zero balance management of volume, which is more conducive to the recovery
of gastrointestinal function after surgery.

Studies such as Dini have shown that goal-directed fluid therapy guided by variability per Bo output (SVV) can maintain the patient's acid-base balance, reduce the incidence of infection, promote postoperative recovery of gastrointestinal function, and shorten the length
of hospital stay.
Low potassium, low sodium, and low magnesium can all cause postoperative bowel paralysis, and hyperchloremia is often accompanied by nausea and vomiting
.
Excessive blood glucose and acidosis lead to delayed gastric emptying, and low blood sugar will lead to accelerated
gastric emptying.

Postoperative recovery: stimulation of the parasympathetic nervous system through early enteral nutrition improves gastrointestinal motility and coordinates autonomic reflexes
.
A meta-analysis of patients undergoing gastrointestinal surgery showed that early oral feeding after surgery could reduce the incidence of postoperative complications and shorten the length of hospital stay, so early oral feeding
after surgery was recommended.
The opioid receptor antagonist Avimopan can antagonize the peripheral effects of opioid analgesics on gastrointestinal peristalsis and secretion by competitively binding to gastrointestinal μ-opioid receptors, without reversing the central analgesic effect
of μ-opioid agonists.

Whether it is gastrointestinal surgery that does not limit the use of opioid analgesics or gastrointestinal surgery that implements ERAS to reduce opioid medication, the application of Avimopan shortens the patient's gastrointestinal function recovery time (gastrointestinal function recovery indicators include the removal of the gastric tube, the first day after surgery, and the encouragement of early activities), shortens the patient's hospital stay and reduces medical costs
.

The serotonin receptor antagonist drug puncabilide can shorten the time it takes
for patients to undergo POGD after surgery.
The same drug Mosabilide also has a similar pharmacological effect and can be used as a prophylactic drug
in patients at high risk of POGD.
In addition, drinking coffee and chewing gum are also measures
to promote the recovery of gastrointestinal function after surgery.
Patients who drank coffee 3 times a day had a significantly shorter postoperative bowel movement and the time it took to eat through mouth was significantly shortened
.
Chewing gum promotes gastrointestinal function recovery
in patients who cannot eat by mouth after surgery by simulating the process of eating.
However, the effect is not obvious
for patients who have already eaten by mouth in the early postoperative period after ERAS.

4.
Treatment of gastrointestinal disorders after surgery

The principles of treatment for POGD are nutritional support, adherence to ERAS as much as possible, and diagnosis and treatment
of the primary cause.
Patients with POGD have a high risk of reflux aspiration, and early identification and placement of a gastric tube is important
.
However, the method of drainage of gastric contents through the gastric tube and the timing of the removal of the gastric tube are inconclusive
.
Early removal of the gastric tube is advocated, but it is inconclusive
whether to remove the drain when the patient has recovered gastrointestinal function or when the drain reaches a specific color or amount.
Such patients can not eat, should be combined with the drainage situation for reasonable fluid management, timely replenishment of patient capacity and electrolyte deficiency
.

During the operation, the patient's internal environment is maintained, the patient's symptoms, signs, and auxiliary examinations are closely observed, and the patient's blood volume, electrolyte level, acid-base balance, etc.
are correctly judged
.
At the same time, as far as possible, adhere to the principle of minimizing the use of opioids, and encourage the promotion of gastrointestinal function recovery
through exercise and chewing gum.
For patients with delayed POGD (>7d), parenteral nutrition
is required according to relevant guidelines.
At the same time, it is necessary to consider whether there are other primary causes, such as small bowel obstruction, anastomotic fistula, etc
.
Such patients may have symptoms
such as fever, abdominal pain, tachycardia, and leukocytosis.
Once the above conditions occur, the etiology should be diagnosed and treated
by imaging as soon as possible.

5.
Summary

At present, there are many studies on the mechanism and clinical strategy of POGD
.
The I-FEED score is a well-established description of postoperative gastrointestinal function status that has been recognized in recent years
.
The inflammatory response and neuroendocrine reflexes are well-defined mechanisms for the development of
POGD.
For the prevention and treatment of POGD, the ERAS concept has important guiding significance
.
Studying the mechanism of POGD and conducting targeted clinical interventions will be more conducive to the outcome of patients and is also the main direction
of future researchers.
At present, the research on POGD is basically derived from gastrointestinal surgery, there are limitations in guiding gastrointestinal recovery after other types of surgery, and focusing on the recovery process of the gastrointestinal tract of patients after more types of surgery may bring new breakthroughs in the study of the mechanism of POGD and further enrich the clinical strategy
of POGD.

Source:Li Yue,Feng Yi,Yan Qi.
Clinical research progress on postoperative gastrointestinal disorders[J].
Journal of Clinical Anesthesiology,2022,38(03):299-303.