An Overview of Gastric Lavage and Nursing for Acute Organophosphorus Pesticide Poisoning Patients
University department, Licun Village Health Center of Rong County, Guangxi, Yulin, 537500, China
Along with the development of an autonomous market economy and the continuous progress of reform, acute organophosphorus pesticide poisoning (AOPP) takes up an increasing portion of first-aid treatments in primary health institutions. Thus, increasing attention has been paid to the effect of gastric lavage and nursing for AOPP patients.
Gastric lavage and nursing plays a crucial role in promoting the treatment of AOPP patients. Hence, this paper will analyse and study the effectiveness of gastric lavage and nursing in AOPP treatment.
Keywords: Acute poisoning; organophosphorus pesticide; gastric lavage; nursing; research
Organophosphorus pesticide, as a kind of organic phospholipid compound, can enter the human body through the respiratory tract, digestive tract and skin, and when combined with acetylcholin esterase to eliminate its activity in decomposition of acetylcholine, it causes an over-stress of the patient’s otherwise normal muscle structure, striated muscle and glands and subsequently results in inhibition and prostration.
Acute organophosphorus pesticide poisoning is a very common urgent case in the emergency department of internal medicine; it is life-threatening and will very quickly take its course. In serious cases, the patient may die of respiratory failure. As an effective method for rescue for acute poisoning patient, gastric lavage and nursing play an active role in clinical cases.
Organophosphorus pesticide can enter human body through three main channels: the mouth — being taken by mistake or intentionally (in suicide cases); skin or mucus — being easily absorbed by skin and mucus when organophosphorus comes into contact with skin during spraying of pesticide on hot days since the skin sweats and pores are enlarged (furthermore, organophosphorus pesticide is often fat-soluable) and through the respiratory tract — as organophosphorus is breathed into the body through the air.
If taken orally, the onset of an attack happens often in 10min to 2h. If absorbed through skin, the symptoms will appear in several hours to six days after contact.
Acute poisoning patients account for 15%~20% of first-aid cases; the figure can go up from 25%~50% in vital medical institutions. Among these cases, AOPP is the most common case and its proportion is increasing in recent years. For oral poisoning patients, gastric lavage is the first choice and plays an important role in the treatment of AOPP, and its correct implementation is sometimes decisive to the success of first-aid treatment. Along with the extensive clinical research on AOPP, gastric lavage has also experienced dramatic changes. Now, the practices of gastric lavage and nursing for AOPP in recent years are summarised in the following sections.
1. Clinical Manifestations of AOPP
1.1 Cholinergic nervous agitation and crisis
1.1.1 Muscarinic symptoms. Spasm of smooth muscle and increased secretion of glands are caused by the stressing of parasympathetic endings. Clinical symptoms include nausea, vomiting, stomachache, hyperhidrosis, watering eyes, running nose, dribbling, diarrhea, over-frequent urination, incontinence, heart rate slowdown, shrinkage of pupils, spasm and increased secretion of bronchus, cough and dyspnea. In extreme cases, patients may suffer from pulmonary edema.
1.1.2 Nicotinic symptoms. The excessive accumulation and stimulation of acetylcholine at the neuromuscular junctions of the striated muscle may cause the fibrillation of striated muscle fibres on the face, eyelids, tongue, four limbs and all over the body, and even the tonic spasm of muscles all over the body. The patient often feels that the body is constrained and compressed, and then suffers from loss of muscle strength and paralysis. In extreme cases, patients may have paralysis of respiratory muscles, resulting in peripheral respiratory failure. In addition, sympathetic ganglions are agitated by acetylcholine, the sympathetic nerve fiber endings after ganglion release catecholamine cause vasoconstriction, resulting in increased blood pressure, heart rate and arrhythmia.
1.1.3 Central nervous system symptoms. After the central nervous system becomes agitated by acetylcholine, there are such symptoms as dizziness, headache, tiredness, ataxia, dysphoria, delirium, convulsion and coma.
1.2 Intermediate Syndrome
Intermediate syndrome (IMS) refers to a series of symptoms caused when enzyme cholinesterase is inhibited for a long time due to delayed excretion of organophosphorus poisons and their redistribution inside the human body, insufficient medicine or other reasons, and due to accumulation in neuronal synapses, and when nicotine receptors on postsynaptic membranes are agitated constantly and de-sensitised by acetylcholine of high concentration, resulting in the blockage of impulse transmission at neuromuscular junctions. Normally, if the symptoms of acute poisoning are alleviated one to four days later, the patient may show a weak respiratory muscle, muscle dominated by motor cranial nerves as well as muscle at proximal ends of limbs. The patient suffers from the paralysis of neck, upper limbs and respiratory muscle. If cranial nerves are affected, the patient may have ptosis of eyelids, difficulty in eye opening and facial paralysis. Muscle weakness may result in peripheral respiratory failure. At this time, respiratory support must be provided urgently. If the situation is not intervened in a timely manner, the patient may die.
1.3 Tardive neurosis of organophosphorus
Normally, AOPP does not leave any sequels. Some patients may be attacked by tardive neurosis 2~3 weeks after acute poisoning symptoms disappear, which mainly affects the ends of limbs and causes paralysis of lower limbs, muscular dystrophy of limbs and other nervous system symptoms. Now, it is widely agreed that this pathological change is not caused by inhibition of enzyme cholinesterase; rather, it results from the ageing of neuropathy target esterase as it is inhibited by organophosphorus pesticide.
1.4 Other manifestations
Dichlorvos, trichlorfon, Parathion, Demeton and other pesticides may cause atopic dermatitis when in contact with skin, and this occurrence may result in blister and peeling. In serious cases, the skin may experience chemical burn, affecting the prognosis. If organophosphorus pesticide drops into the eyes, the occurrence will cause conjunctival congestion and shrinkage of pupils.
2. Implementation of Gastric Lavage
Gastric lavage can be applied to all poisoning patients except corrosive poisons. The earlier, the better. Normally, it can achieve best effect within 6h after the patient is poisoned. If a patient takes too much poison, even though the poison may be excreted by the stomach after being absorbed, gastric lavage should still be performed even after 6h following poisoning.
The implementation of gastric lavage is not advised for the following patients:
① Corrosive poisoning patients; ② Patients suffering from convulsion and vomiting of excessive blood; and ③ Patients with history of varices of esophagus or upper gastrointestinal bleeding. 
2.3 Mechanism for Selection of Solution during Gastric Lavage
During operation of gastric lavage for AOPP patients, the mechanism for selection of solution is as follows: the solution for gastric lavage for AOPP patients is utilised to remove the poisons or stimulants inside the stomach in order to reduce poison absorption and thereby saving the patient. At the same time, it alleviates other symptoms, including stomach lining edema, nausea and vomiting, thereby improving clinical comfort of the patient. For this purpose, a suitable solution for gastric lavage should be selected based on clinical manifestations, hyponatremia and other syndromes of a patient. When saline is selected for gastric lavage, it can help reduce the loss of sodium and the incidence of hyponatremia, shorten the duration of hospitalisation and lower fatality rate. If saline is combined with (0.001% or 0.008%) nonadrenaline for gastric lavage, it can help reduce the incidence of stomach lining bleeding, lower absorption of poison in the stomach, and prevent harmful effects on the patient’s heart rate, blood pressure and urine volume. Hence, saline or mixture of saline solution with (0.001% or 0.008%) nonadrenaline, valuable to clinical cases, can be selected for gastric lavage for AOPP patients.
2.4 Ways to Insert Gastric Tube
Gastric lavage is crucial to AOPP treatment, so the quick and effective insertion of the gastric tube is key to the operation of gastric lavage. Now, there are mainly two ways to insert gastric tube, i.e. insertion through mouth and insertion through nasal passage.
The insertion of gastric tube through nasal passage: for a conscious patient, the gastric tube is inserted from the nostril. When it reaches the throat, the patient is asked to swallow to quickly insert the tube to the required length.
For an unconscious patient, a medical worker lowers the patient’s head backward to insert the gastric tube from the nostril. When it reaches the epiglottis, the medical worker raises the patient’s head to reach the lower jaw close to the manubrium, in order to insert the tube to the required length. Through this way, the occurrence of syndromes, including nausea, vomiting as well as secretions in the mouth can be lowered, reducing the workload and labor intensity of the medical worker.
The insertion of gastric tube through the month: for a conscious patient, the gastric tube is inserted through the patient’s mouth. When it reaches the throat, warm water is fed to the patient, to ease the insertion of the gastric tube quickly through normal swallowing. For the unconscious patient, the laryngoscope will be adopted to widen the exposed opening of the oesophagus and throat, with a guiding wire placed into a thick tracheal tube. After the tracheal tube passes through the opening of the oesophagus, the guiding wire is pulled out. The gastric tube will be covered with paraffinic oil and inserted into the stomach slowly through the tracheal tube. Through this method, the mistake of inserting the gastric tube into the trachea as well as the incidence of aspiration pneumonia and suffocation can be lowered, while alleviating the physiological and psychological pains of patient. 
3. Nursing for Gastric Lavage
3.1 Psychological nursing
During the operation of gastric, psychological nursing should be provided. The nurse must carefully explain the importance and necessity of gastric lavage to the patient and his/her family, so that the patient becomes more confident in overcoming the disease. Additionally, the nurse should cultivate communication with the patient, encouraging him to speak about his feelings while being a keeper of secrets. If a patient encounters financial difficulty during treatment, the cost should be discussed after operation in order to complete the gastric lavage with the cooperation of the patient with his family. 
3.2 Methods of gastric lavage
The first method of gastric lavage includes perfusion, as well as the electric attractor gastric lavage and automatic gastric lavage machine.
The second involves selection of the correct gastric tube. Generally, the gastric tube with a large diameter and certain degree of firmness should be selected, such as 26# gastric tube. A few side holes can be cut on the head so as to avoid blockage or negative pressure to suction tube which may lead to wall collapse and poor drainage.
The third refers to several key points of the intubation, namely, removing the foreign bodies in the oral cavity of the patient, confirming the gastric tube has been inserted into the stomach, then extracting the high-concentration poison in the stomach, and finally conducting lavage.
The fourth is gastric lavage position. The left-lateral position of the patient with lowered head and elevate feet should be adopted so that water can dilute poison and accelerate the outflow of poison.
The fifth is the duration of gastric lavage. Acute organophosphorus pesticide poisoning patients should adhere to the principle of early washing, and not be hindered by the emptying time of 4-6h; the sixth being reserved for sickness observation. Samples which are firstly extracted should be kept for toxicant identification, and changes of patients in consciousness, pupils and vital signs should be closely observed in the process of gastric lavage. Do not use water or morphine to inducing vomit in order to reduce the incidence of respiratory depression symptoms; the seventh is to keep the gastric washing temperature at 30-35℃, because overheating can promote local blood circulation and accelerate the absorption, and super-cooling may accelerate gastric peristalsis, thus promoting the poison drain into the lumen.
The eighth is to let the gastric tube stay for a certain amount of time after gastric lavage has been completed. Do not pull the tube out immediately so as to avoid gastric lavage again. As for AOPP patients, the gastric tube should be retained for more than 24h to facilitate recurrent gastric lavage. 
With the development of the times and the progress of the society and medical technology, the rescue rate for AOPP patients accounts for 15%-21% of the total. The main reason is the abuse of pesticides include suicide, incorrect consumption of, etc. In the process of rescue, patients will not only be given anti-drug treatment but they also need to receive late gastric lavage treatment and post-nursing. Therefore, this paper studies the gastric lavage operation and gastric lavage nursing measures from the perspective of gastric lavage for AOPP patients, in order to provide scientific gastric lavage solution and nursing measures for promoting the clinical rescue efficiently.
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