With the adjustment of the national response to the new crown epidemic, the number of patients with respiratory diseases in many places across the country has increased on a large scale, and medical institutions, especially the intensive care departments of general hospitals, are facing the dilemma of serious shortage of medical oxygen supply and pressure. Under this circumstance, the First People's Hospital of Shuangliu District, Chengdu immediately activated emergency measures, formulated a transformation plan, and successfully completed the emergency transformation, ensuring the safety of the people's lives.
01Introduction to the Hospital and Intensive Care Medicine Department
The First People's Hospital of Shuangliu District, Chengdu has a construction area of 210,000 square meters, with 1,500 planned beds and 1,100 open beds. The hospital has 4 provincial-level key specialties and 9 municipal-level key specialties, and is a designated hospital for severe patients infected with the new coronavirus in Shuangliu District. The Department of Critical Care Medicine of the hospital is a provincial key specialty, which can skillfully carry out continuous blood purification therapy, hemoperfusion, plasmapheresis, artificial liver therapy, prone ventilation treatment of severe ARDS, etc., with ECMO, multi-functional monitor, ventilator, continuous bedside blood purification system, bedside ultrasound and other equipment, 46 planned beds, 20 open beds, and about 20 daily patients, including about 17 patients on ventilators (5 on non-invasive ventilators, 10 on invasive ventilators, 2 people for high-flow ventilators).
02 Medical oxygen supply capacity and usage before transformation
The hospital adopts the finished liquid oxygen supply plus busbar as the emergency oxygen supply method, and sets up a total of 4 vertical liquid oxygen storage tanks with a volume of 5m³, 2×10 automatic oxygen busbars as the backup oxygen supply source, and 4 liquid oxygen vaporizers with a vaporization capacity of 400 Nm³/h are used alternately, and a total of 1916 oxygen inhalation terminals are designed. There are 3 pipes at the output end of the cylinder, 1 φ38×3 pipeline is supplied to the inpatient department, and 2 φ28×2 pipelines are supplied to the outpatient medical technology building. Among the pipes supplying the outpatient medical technology building, one is for the operating room and intensive care department, and the other is planned to supply the hyperbaric oxygen chamber, which is not in use for the time being. The oxygen supply pipeline of the intensive care department is connected from a special shaft for medical gas in the outpatient medical technology building. The oxygen is connected to the terminal of the intensive care ward through the vertical oxygen main, the three-layer pressure regulating box, and the three-layer oxygen supply horizontal trunk pipe in turn. The horizontal main pipe reaching the third floor and the horizontal branch pipe of the seven partitions are all φ16×1.5, and each terminal branch is φ10×1.5. Gas consumption before the transformation: Before December 2022, the total monthly oxygen usage of the whole hospital was 40 000~50 000m³, and the oxygen input pressure of the sub-cylinder was 0.66MPa and the output pressure was 0.5MPa. On average, it is filled once every 6 days, and the filling volume is 10m³/time (liquid oxygen). The monthly oxygen consumption of the intensive care department is about 4500 m³, the oxygen flow rate is 6.25 Nm³/h, and the output pressure of the two-stage pressure reducing tank is 0.4 MPa.
03 Respond to the changes in oxygen consumption after policy adjustment
In December 2022, with the adjustment of COVID-19 response policies, there was a significant increase in the number of patients infected with the novel coronavirus and severe cases admitted to hospitals. Among them, the number of respiratory, geriatric, cardiology and intensive care wards has increased significantly, and most patients need oxygen therapy, or even high-flow oxygen. On December 8, 2022, in response to the growing demand for patients infected with the novel coronavirus, the intensive care department urgently opened its beds to 33. From December 2022 to February 2023, a total of 268 patients with novel coronavirus infection were admitted to the general practice. During the peak period, 36 patients were admitted per day, including 4 patients on general oxygen, 10 users on non-invasive ventilators, 18 users on invasive ventilators, and 4 users on high-flow ventilators. After calculation, the total oxygen supply of 4 vertical liquid oxygen storage tanks with a volume of 5 m³ and 4 liquid oxygen vaporizers with a vaporization capacity of 400 Nm³/h designed by the hospital can meet the daily needs of the whole hospital and the epidemic situation. At the same time, the management personnel of the liquid oxygen station adjusted the input pressure of the cylinder to 0.72MPa and the output pressure to 0.6MPa, strengthened the management of the carburetor and carried out daily de-icing maintenance. However, with the rapid increase in oxygen consumption in intensive care medicine, the oxygen supply pressure is less than 0.3MPa. On January 1, 2023, there was a large-scale alarm on the ventilators of the intensive care medicine department, and 31 non-invasive, 1 invasive, and 3 high-flow ventilators all reported that the oxygen pressure was too low (the suitable pressure of ordinary ventilators was 0.4~0.5MPa, and the alarm pressure was 0.3~0.55MPa). The two-stage decompression box was inspected on site, the inlet pressure was 0.6MPa, the outlet pressure was 0.5MPa, the flow rate was 200L/min, and the terminal pressure of the intensive care department was 0.25MPa, which was lower than the alarm pressure set by the ventilator (0.3MPa).
04Problem analysis
(1) Measurement of the oxygen requirement of the intensive care medicine department during the epidemic prevention and control period
According to the formula Q=∑[Qa+Qb(n-1)η] for the calculation flow rate of the gas source of the medical gas system in the "Technical Code for Medical Gas Engineering" (GB 50751-2012), combined with the requirements of the "New Coronary Pneumonia Designated Treatment Hospital Establishment Management Specification" and ventilator parameters, according to the general ventilator oxygen inhalation (10~25L/(min·bed)) for 90% of patients, and 10% of patients use high-flow inhaler oxygen (50~60L/ (min·bed)), The oxygen volume for the 46 planned beds was calculated to be 79.5 Nm³/hour (table 1).
Table 1 Parameters for calculating medical oxygen flow
Note: The data comes from Appendix B of the Technical Code for Medical Gas Engineering (GB 50751-2012).
(2) Equipment and pipelines calculated according to the flow rate
According to the Code for the Design of Industrial Metal Pipelines (GB 50316-2000), the diameter of the original main pipe of the intensive care medicine department is φ16×1.5, the oxygen flow rate in the pipeline is calculated at 10m/s and the working pressure is 0.4MPa, and its oxygen delivery capacity is only 23.9Nm³/h. At the same time, the maximum flow rate of the secondary oxygen pressure reducing tank is 40Nm³/h, which cannot meet the requirements of the terminal gas consumption and pressure of 46 beds, resulting in the terminal pressure as low as 0.25MPa, and the normal use of ventilators and high-flow oxygen therapy instruments cannot be used. In order to meet the requirements of 79.5Nm³/h, a pipe with an inner diameter of 23.7mm and a matching high-flow pressure reducing box should be used to keep the terminal pressure at 0.4~0.5MPa (Table 2).
Table 2 Calculation table of medical oxygen pipelines
05Renovation plan and construction management
In order to completely solve the gas problem of intensive care medicine, according to the calculated data, it is necessary to transform and replace the pipe diameter and secondary pressure reducing box.
(1) Design scheme and system selection
Considering that if the original φ16×1.5 pipeline is abolished and the new φ28×2 pipeline is built in all intensive care medicine departments, there is a waste of resources, and finally the original pipeline is retained for oxygen supply in bed area 43~46, and the new pipeline is used to supply the remaining 42 bed area, which can not only save money, but also ensure that under special circumstances, the intensive care medicine department has two pipelines to supply oxygen, which is safer.
The hospital originally designed a hyperbaric oxygen chamber pipeline of φ28×2, which was not used because the hyperbaric oxygen chamber treatment room has been cancelled. During the transformation, a φ28×2 main pipe can be drawn from the original design of the hyperbaric oxygen chamber pipeline to the tube well, from the first floor to the third floor through the pipe well, and then from the third floor ceiling to the third floor of the intensive care medicine department in District 7. The new pipeline is connected to φ16×1.5 branch pipes at the end of each area of the intensive care medicine department, and the branch pipes are connected to the original φ10×1.5 pipes at the end of the crane tower in the room to ensure the safety of gas at the end of the gas supply.
Considering that the brands, varieties and quantities of ventilators used in the intensive care medicine department are different, and the gas flow and pressure requirements are high, a new high-flow pressure reducing box (output pressure is 0.2~0.8MPa; The rated flow rate is 100~170Nm³/h), and the air supply pressure in the intensive care ward is adjusted separately through the pressure reducing box.
One flowmeter is installed at the outlet end of the new high-flow pressure reducing box, and the flowmeter measures the oxygen consumption of the department. At the same time, a signal line is laid in the tube well in Zone 3 to connect to the tube well in Zone 4, and connect to the original installation of the secondary pressure reducing box and flow monitoring equipment.
The medical oxygen pipes are all made of stainless steel pipes that are consistent with the original design.
The overall design scheme of hospital medical oxygen ensures that the pressure of the air source side meets the most unfavorable end of the whole hospital, and the pressure regulating box is provided with the horizontal pipeline of each area on each floor to ensure the stability of the inlet pressure of each area, and the stop valve of adjustable pressure is also set on each branch pipe at the same time, so as to ensure that the pressure loss at the proximal end and the distal end is negligible as much as possible.
(2) Renovation construction
1. Preparation for construction
The construction is divided into two stages: the first stage is the preliminary construction carried out under the normal operation of the hospital and the department, and this stage does not affect the normal operation of the department; The second stage is the construction that can only be carried out if the operation of the department is affected or even suspended. In principle, sufficient time should be given to the first phase to minimize the construction time and scope of the second phase. In this renovation, it is planned to complete the laying of new pipelines outside the department, and the customization and installation of new high-flow pressure reducing boxes in the first stage.
2. The first phase of construction
The original hyperbaric oxygen chamber pipeline was diverted to the main pipe of the No. 3 tube well using a tee (the original trending pipeline of the hyperbaric oxygen chamber was retained to provide conditions for the subsequent use of the department to increase the number of beds), and the installation work was completed in 2 working days; The horizontal pipe and the new branch pipe were welded on the floor, and the pressure reducing device was installed, which was completed in 2 working days. After the new pipelines and facilities and equipment are installed in place, the suppression, commissioning and on-site acceptance will be completed.
3. Phase 2 construction
All bed ventilators were converted into gas cylinders for oxygen supply, and the outlet valve of the secondary decompression tank for oxygen supply in the center of the intensive care department was closed, and the oxygen in the original and auxiliary tubes was emptied. According to the layout of the department, the intensive care medicine department has a total of 8 rows of wards, and the auxiliary pipes of the 7 rows of wards (beds 1~42) are cut off, and the new pipelines are connected to beds 1~6, 7~12, 13~18, 19~24, 25~30, 31~36, and 37~42 respectively. The original intensive care department laid pipes to continue to be used, but it was only used for 1 row of wards (beds 43~46), with a total of 4 beds. The above two steps are carried out synchronously and completed in 1 working day.
(3) Construction management and emergency support
After the transformation plan is discussed by the hospital, it will be reported to the higher-level competent department, and the higher-level competent department will coordinate with the surrounding medical institutions to make an emergency plan for backup liquid oxygen support and patient transfer for treatment in an emergency.
According to the number of oxygen patients, 30 sets of pressure reducing valves and 60 bottles of 40L liquid oxygen are prepared in advance to ensure the oxygen supply of each patient, and 15 bottles of liquid oxygen are reserved in the liquid oxygen station for backup. In advance, all spare liquid oxygen cylinders are connected with special connecting pipes and valves, the pressure and flow rate are adjusted, and at the same time, temporary pipelines are connected from adjacent departments as backup in case of emergency.
The construction site is equipped with dry powder fire extinguishers and full-time fire safety officers.
All welds are performed above the outer hallway of the ward, away from the patients and oxygen cylinders in the ward.
06 Transformation results
After the renovation is completed, after the commissioning of the new and old pipeline systems, the two oxygen supply pipelines (φ28×2+φ16×1.5) of the intensive care medicine department can reach a gas supply pressure of 0.45MPa and a flow rate of 103.4Nm³/h. This renovation effectively solves the oxygen supply needs of the intensive care department after all 46 beds are opened, and can also ensure the emergency requirements of oxygen supply for ventilators in the event of a similar public health emergency.
07 Summary and analysis
Special attention should be paid to the following points when designing and renovating:
"Technical Code for Medical Gas Engineering" (GB 50751-2012), "Code for Design of Oxygen Station" (GB 50030-2013), "Code for Design of Industrial Metal Pipes" (GB 50316-2000), etc., are all applicable to conventional design, and do not consider the needs of public health events such as the new crown epidemic, and the oxygen flow parameters of various brands of ventilators have been continuously improved in recent years (the maximum flow rate can reach 80L/min). The design and service life of the pipeline of the oxygen supply system of medical institutions is generally 30 years, and the later expansion is more complicated, so it is recommended to refer to the epidemic situation and equipment parameters in the design of new projects or the renovation of existing buildings. For key departments such as operating rooms, intensive care medicine, cardiovascular medicine, rescue rooms, etc., it is recommended to design the oxygen supply pipeline as a standby and one use, so as to ensure that it can be switched at any time in case of emergency, and can also be used at the same time. Before the transformation, organize the heads of the medical department, the nursing department, the hospital infection department, the equipment department, the engineering department, and the transformation department to attend the meeting, arrange the on-site commander-in-chief, inform all personnel of the transformation plan, emphasize patient safety, and make emergency preparations for emergencies such as equipment, personnel, consumables, and drugs.
Before construction, the construction unit must go to the hospital management department to handle the approval process of construction work and related safety technology disclosure. Welding, cutting and other operations need to be carried out by experienced personnel with special operation certificates, which can ensure the quality of construction and shorten the construction time as much as possible. It is strictly forbidden to operate without a license, and all operators who should be certified to work shall submit relevant documents to the hospital for registration and filing.
All employees of the construction unit must wear complete protective tools, otherwise they are not allowed to work; The on-site construction unit must do a good job of on-site vigilance measures and demarcate a safe area.
Departments with special environmental requirements must be guided by the hospital sensory department to do a good job of sanitizing the construction site and post-construction.
After the construction is completed, the new pipeline is cleaned and inspected, and the holes in the wall are plugged in a standardized manner.
This article is from:
Wan Hongxia. Reconstruction of oxygen supply system in intensive care department of medical institution in response to public health events[J].Chinese Hospital Construction and Equipment,2024,25(6):60-63.)
Author's Affiliation:
The First People's Hospital of Shuangliu District, Chengdu, and West China Airport Hospital of Sichuan University
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