Research on injection flow velocity planning method for embolic agent injection system / 生物医学工程学杂志

Interventional embolization therapy is widely used for procedures such as targeted tumour therapy, anti-organ hyperactivity and haemostasis. During embolic agent injection, doctors need to work under X-ray irradiation environment. Moreover, embolic agent injection is largely dependent on doctors' experience and feelings, and over-injection of embolic agent can lead to reflux, causing ectopic embolism and serious complications. As an effective way to reduce radiation exposure and improve the success rate of interventional embolization therapy, embolic agent injection robot is highly anticipated, but how to decide the injection flow velocity of embolic agent is a problem that remains to be solved. On the basis of fluid dynamics simulation and experiment, we established an arterial pressure-injection flow velocity boundary curve model that can avoid reflux, which provides a design basis for the control of embolic agent injection system. An in vitro experimental platform for injection system was built and validation experiments were conducted. The results showed that the embolic agent injection flow speed curve designed under the guidance of the critical flow speed curve model of reflux could effectively avoid the embolic agent reflux and shorten the embolic agent injection time. Exceeding the flow speed limit of the model would lead to the risk of embolization of normal blood vessels. This paper confirms the validity of designing the embolic agent injection flow speed based on the critical flow speed curve model of reflux, which can achieve rapid injection of embolic agent while avoiding reflux, and provide a basis for the design of the embolic agent injection robot.

The effect of injection speed on remifentanil-induced cough in children / 대한마취과학회지

BACKGROUND: Remifentanil sometimes elicits cough during induction of anesthesia, as with the use of other fentanyl congeners. We designed this study to investigate the incidence of remifentanil-induced cough (RIC) in children and to evaluate the effect of injection speed on RIC. METHODS: One hundred twenty ASA physical status I-II patients, aged 3-12 yr, undergoing general anesthesia were enrolled in the study. Patients were randomly assigned to one of the three groups. Patients in Group R30 received remifentanil 1.5 microg/kg at a constant rate over 30 s. Patients in Group R45 received remifentanil 1.5 microg/kg over 45 s, and patients in Group R60 received remifentanil 1.5 microg/kg over 60 s, respectively. Episodes of cough were recorded and graded as mild (1-2), moderate (3-4), or severe (5 or more). Mean arterial pressure (MAP), heart rate (HR), and SpO2 were recorded on arrival in the operating room (baseline) and 1 min after remifentanil infusion. RESULTS: The incidence of RIC was 33.3% in Group R30 (13 of 39 patients), 17.9% in Group R45 (7 of 39 patients), and 5.0% in Group R60 (2 of 40 patients). Patients in Group R60 had a significantly lower incidence of RIC than those in Group R30 (P = 0.001). The MAP, HR, and SpO2 values were not significantly different between groups. CONCLUSIONS: When intravenous remifentanil 1.5 microg/kg was administered in pediatric patients, the incidence of RIC decreased from 33 to 5% by increasing the injection time from 30 to 60 s. Remifentanil should be administered slowly over 60 s in children to suppress cough during anesthesia induction.

The Effect of Injection Speed of Local Anesthetic on Success Rate of Unilateral Spinal Anesthesia / 대한마취과학회지

BACKGROUND: The relationship between the injection speed of a local anesthetic and the success rate of unilateral spinal anesthesia has been a controversial issue. The aim of this thesis was to identify any significant effects of the drug injection speed on the success rate of unilateral spinal anesthesia. METHODS: Forty patients were randomly allocated into 2 groups, group R and S. The injection speed was 4 ml/min in group R (n = 20) and 1 ml/min in group S (n = 20). Hyperbaric 0.5% bupivacaine 10 mg was injected via a syringe pump. The drug was administered at the L3-4 intervertebral space with the patient in the lateral decubitus position, which was maintained for 20 minutes after the injection. A spinal sensory block was assessed by examining the temperature sensation using an alcohol-sponge. The motor block was evaluated using the modified Bromage scale and the dependent and non-dependent sides were compared. RESULTS: Significant differences (P<0.05) were observed in the success rate of unilateral motor paralysis (45% in group R vs 90% in group S). There were no significant blood pressure differences between the two groups 5, 10, 15, 30 and 60 minutes after injecting the hyperbaric 0.5% bupivacaine. CONCLUSIONS: The injection speed of local anesthetics is one of the crucial factors for achieving a unilateral spinal anesthesia. Therefore, it is important to maintain a slow injection speed of a local anesthetic in unilateral spinal anesthesia.

Effect of Injection Speed on the Anesthetic Level and Duration of Hypobaric Spinal Anesthesia with 0.1% Tetracaine in Jack-Knife Position at 15o Head-down Tilting / 대한마취과학회지

BACKGROUND: The speed of injection of local anesthetic solutions into the subarachnoid space may influence the spread of these agents in the cerebrospinal fluid by the amount of turbulence generated, especially with large volume. To determine the proper injection speed of anesthetics in hypobaric spinal anesthesia on jack-knife position, the anesthetic level and duration were measured with the fast or slow injection speed. METHODS: Twenty patients for perianal surgery in jack-knife position under hypobaric spinal anesthesia were randomly assigned to one of two groups. Tetracaine (0.1%) in distilled water 5 ml was administered to all the patients. Group I patients received the drug with the speed of injection as 5 ml/20 sec (15 ml/min) and the others (Group II) as 5 ml/4 min (1.25 ml/min). The mean arterial pressures and heart rates at the preanesthetic period, and 5, 10, 15 and 20 min after the end of injection were measured. The anesthetic levels at 5, 10, 15 and 20 min after the injection and anesthesia duration were measured. RESULTS: There was no significant difference in mean arterial pressures, heart rates and anesthetic duration between two groups. The anesthetic level 20 min after the injection was higher in Group I than Group II, and not different at the other time sequences. CONCLUSION: At the injection speed within 1.25-15 ml/min in hypobaric spinal anesthesia on jack-knife position at 15o head-down, we acquired appropriate anesthetic level and duration for perianal surgery without any undesirable effects.

An Experimental Study on the Effect of Measurement Parameters and Hydrocephalus on the Pressure Volume Index

To study the effect of measurement parameters and hydrocephalus on the pressure volume index(PVI), PVI study was performed in 5 normal and 5 kaolin-induced hydrocephalic cats. The effects of injection volume, speed, laterality and influence of increased intracranial pressure(ICP) in normal and hydrocephalic cats on the PVI value were evaluated. The results were as follows; 1) Larger injection volume, increased ICP by continuous infusion, and presence of ventriculomegaly made the PVI value significantly higher(p<0.01, p<0.001, p<0.05, respectively). 2) Rapid injection made the PVI value significantly lower(p<0.01). 3) Increase of ICP accentuated the effects of injection volume and speed significantly(p<0.01). 4) There was no difference between the PVI values measured with injection into the ipsilateral lateral ventricle and those measured with injection into the cantralateral lateral ventricle. 5) With the above results, it is considered advisable to perform the PVI study with constant injection volume, speed and ICP.