1 Selection of safe indwelling position
There are many places of intravenous indwelling needle in children, such as scalp vein, superficial vein of limbs, axillary vein, external jugular vein and inguinal vein. The indwelling time of different indwelling sites is obviously different. Ai Fang [1] made a clinical observation on 1 559 hospitalized children, and found that there was no difference in indwelling time between scalp vein and upper limb vein in neonatal group, which was longer than lower limb vein. In infant group, the time of scalp vein indwelling is the longest, and the time of lower limb vein indwelling is the shortest; There was no difference in limb indwelling time in school-age group. Therefore, scalp vein is the first choice for venipuncture in newborns and infants, followed by upper limb vein. However, for children with intracranial hemorrhage and neonatal ischemic encephalopathy, scalp puncture should be avoided as far as possible to reduce movement and prevent bleeding from aggravating [2]. Children with relative cooperation can be indwelling in external jugular vein [3]. Neonates should choose axillary vein catheterization, which lasts longer than superficial veins of limbs or scalp veins and is easy to fix and care for [46].
2 Puncture skills
The child is small, the puncture operation is not coordinated, and the vascular cavity is small. Traditional puncture methods often make catheter delivery difficult. Hu Xiaowei et al. [7] improved this method, always tightening the skin with his left hand, holding the needle wing with his right hand, and puncturing at an angle of15 ~ 30. Reduce the angle after returning blood, continue to insert the needle for about 2 mm, continue to tighten the skin with the left hand, and continue to slowly inject normal saline with the right hand, so as to fill the blood vessels at the puncture site and prevent blind puncture of blood vessels. It is more effective for children with small blood vessels, insufficient blood volume and shock. It has been reported [8] that the scalp vein of newborns is dendritic, while the great saphenous vein is relatively curved when walking. By withdrawing the needle core step by step for many times, the outer sleeve can be supported on the needle core as much as possible in the process of blood vessel walking, so as to prevent the outer sleeve from folding during catheter delivery and facilitate the indwelling needle to smoothly pass through bending.
3 Fixation method
3. 1 head fixing method
The child is active, and the adhesive tape for fixing the indwelling needle is easy to loosen, which leads to tube detachment and affects the indwelling time. Therefore, Huang Wenjing et al. [9] paved the edges and corners of indwelling needle with a small amount of cotton, then fixed it with 3M membrane, and then fixed it with No.5 elastic mesh sleeve, which can effectively prolong the indwelling time. Because the elastic mesh sleeve is elastic and breathable, it will not bring discomfort to children. Fixing the head vein indwelling needle with 3M surgical self-adhesive bandage can also prolong the indwelling time [10].
3.2 limb fixation
Newborns have delicate skin, and their limbs are less active than babies. Zhang [1 1] used sponge instead of splint to fix the venous indwelling needle in the limb, which made the limb have good flexibility when moving, and avoided local edema, catheter shedding and accidental injury to the limb when splint was fixed. In order to prevent the needle handle and heparin cap from being pressed locally and causing local crush injury, when fixing the indwelling needle, pad a small amount of cotton on these parts and fix them, then put the baby's small hand in cotton gloves, wear socks with moderate elasticity on his feet, or wrap it with a small towel [12].
Four-tube seal
4. 1 Selection of sealing fluid
4. 1. 1 saline and heparin solution
Sealing the tube is to fill the lumen of indwelling needle with liquid, increase the pressure in the lumen, prevent blood from flowing back and avoid blocking the tube. Because children are different from adults, many nurses have done a lot of clinical research in order to find a safe and effective sealing scheme. It is reported that [13] normal saline instead of heparin saline can maintain the longest sealing time of indwelling needle in 66 children 16 h, and Rao Qinghua et al. [14] compared the sealing of indwelling needle with normal saline and heparin solution in 546 hospitalized children. The results show that the sealing effect of heparin solution is obviously better than that of normal saline, and the indwelling time is relatively prolonged. It is considered that physiological saline can prevent blood coagulation and tube blockage under certain conditions, but in critical situations or some pathological situations, when blood is in hypercoagulable state, the anticoagulation function in the body is weakened and the microcirculation changes. Therefore, heparin saline should be properly selected to seal the tube according to the condition, so as to improve the indwelling effect.
4. 1.2 Selection of sealing fluid for children with hematological diseases
Yan Xu et al [15] reported that patients with hemodynamic problems, such as hypercoagulability or bleeding tendency, are advised not to use indwelling needles. However, Rao Qinghua et al. [14] compared the coagulation time, mean values of platelets and red blood cells of 77 cases before and after heparin saline occlusion, and there was no significant difference. He believes that sealing the tube with heparin solution is not taboo for children with hematological diseases. It can be used except those with obvious bleeding tendency. In the same way, Mou Yuanfen [16] made a comparative study on 36 children with idiopathic thrombocytopenic purpura (ITP) with heparin and normal saline. The results showed that heparin sealing solution had no effect on coagulation function and platelet count of ITP children, and did not aggravate the original bleeding tendency of children, and the retention time was significantly longer than that of normal saline sealing solution. However, Amway and others [17] think that patients with hematological diseases such as thrombocytopenia, hemophilia, aplastic anemia and heparin allergy should choose sodium citrate solution to seal the tube. 2.5% sodium citrate can reduce the concentration of calcium ion in blood and play an anticoagulant role.
4. 1.3 others
It is also reported that 1∶5( 1 maintenance solution plus 5 normal saline, maintenance solution containing 1.33% sodium citrate, 0.47% citric acid, 3% glucose) is used for sealing intravenous indwelling needles in children [18].
4.2 Selection of concentration and dosage of sealing liquid
Small blood vessels in children, too much sealing fluid, long injection time and uneven strength can damage vascular endothelium and form thrombophlebitis. Therefore, the safe and effective quantitative indicators of heparin are: newborn 0.5 U/mL, 3 years old 1u/mL ~ 5 U/mL, 7 years old 5u/mL, 14 years old 5u/mL ~ 12.5 U/mL. However, it has also been reported [19,20] that the retention time of 3 ml heparin solution is obviously longer than that of 2 mL heparin solution. It is considered that 2 mL heparin solution contains relatively little heparin solution, which is easy to block the tube and shorten the retention time.
4.3 Pipeline sealing method
Sealing the tube is the key to the success of indwelling, and proper methods can prolong the indwelling time. Jackie et al. [19] discussed 120 neonatal tube sealing, and thought that the days of indwelling by injecting 3 mL heparin solution evenly into trocar on the inclined surface of needle were obviously longer than the days of remaining 1 mL after injecting 2 mL into trocar. The reason is that the density of heparin cap rubber is extremely high, so it is easy to pull out the needle from the trocar when pulling out the needle, and the purpose of positive pressure sealing cannot be achieved. However, only the inclined plane enters the trocar and 3 mL heparin solution is injected evenly, which will not cause negative pressure sealing and prolong the indwelling time. Wei Juying and others [20] think that the push-back sealing method has certain disadvantages. Because it is difficult to grasp the uniform needle drawing speed, it is easy to cause negative pressure to seal the tube, leading to blood coagulation and tube plugging.
5 Prevention of phlebitis
5. 1 vascular selection
Different blood vessels should be selected according to different age, illness, use and vascular condition. The selected blood vessels should be soft, straight, elastic, accessible and well filled, avoiding joints [2 1]. Wang Huixian and others [3] think that the indwelling time of external jugular vein is long and the incidence of phlebitis is low. If the neck condition permits, the child can be placed in the external jugular vein with relative cooperation. Hu et al. [22] reported that axillary vein can be used for catheterization when rescuing critically ill infants. The axillary vein is a large vein, and the input vasoactive drugs quickly enter the circulation with the blood, which reduces the stimulation of drugs to local blood vessels, and has a large diameter, and the indwelling needle floats in the blood vessels after being inserted into the blood vessels; However, the scalp, upper limbs and lower limbs have small venous vessels, slow venous return speed, and local vascular walls are stimulated by drugs for a long time, which is prone to phlebitis. Zhu Qin et al. [5] think that the success rate of axillary vein indwelling puncture in premature infants is high and the complications are few. The diameter of axillary vein is thick and straight, the blood is smooth, the drug has little stimulation to blood vessels, and the activity of axillary region is small, so as to avoid mechanical stimulation and reduce phlebitis.
5.2 Selection of indwelling needle
Choosing indwelling needle suitable for blood vessel thickness can reduce the occurrence of phlebitis. The corresponding type of intravenous indwelling needle should be selected according to the different age and condition of children. Infants generally choose 24G fine cannula, and surgical and older children can choose 24G and 22G indwelling needles [2 1].
6 missionary work
According to the characteristics of children, we should give targeted guidance, inform the parents of newborns to avoid touching the indwelling needle during feeding and sleeping, emphasize the care of caregivers in infancy, and give correct guidance to school-age children [23] Medical staff, parents and children should participate in the maintenance of indwelling needles to prolong the indwelling time.
To sum up, in order to ensure the safe and effective indwelling of intravenous indwelling needles in children, we should choose the appropriate blood vessels and indwelling sites according to the age, illness and vascular conditions of children, master the puncture skills skillfully, properly fix and effectively seal the tubes, and give timely education.