Blood Gas Analyzer

What is blood gas analysis?

A blood gas analyzer is a medical device used to measure indicators such as oxygen, carbon dioxide, and pH in human blood. It collects arterial blood samples from patients and uses chemical sensors and electronic instruments to analyze the gas content and acid-base balance in the blood, thereby helping doctors assess the patient's respiratory function, metabolic state, and acid-base balance.

Main parts of a blood gas analyzer

1. Sampler: used to collect arterial blood samples from patients. Needle puncture is usually used to collect blood to avoid unnecessary pain or trauma to the patient.

2. Sensor: used to measure the gas content and acid-base balance in the blood. Common sensors include pH electrodes, oxygen electrodes, carbon dioxide electrodes, etc.

3. Display: used to display measurement results. Modern blood gas analyzers are usually equipped with high-resolution LCD screens that can clearly display the values and trend graphs of various parameters.

4. Computer system: used to process and store measurement data. Modern blood gas analyzers are usually equipped with high-performance computer systems that can quickly and accurately analyze data and generate reports to facilitate doctors to make diagnosis and treatment decisions.

Common indicators of blood gas analysis

Indicators of acid-base balance: pH, partial pressure of carbon dioxide (PaCO), bicarbonate (HCO), base excess (BE).

Oxygenation indicators: partial pressure of oxygen (PaO), oxygen saturation (SaO).

Electrolytes: K, Na, Cl, Mg, Ca,;

Others: lactic acid (Lac), blood glucose (Glu), hemoglobin (Hb), hematocrit (Hct)

pH: negative logarithm of [H] concentration in arterial blood, normal value is 7.35~7.45, average 7.4. pH>7.45 is alkalemia; pH<7.35 is acidemia; normal pH cannot rule out the absence of acid-base imbalance, and venous blood pH is 0.03~0.05 lower than arterial blood.

PaCO: pressure generated by physical dissolution of CO molecules in arterial blood, normal value is 35~45 mmHg, average 40 mmHg. Extreme value: <10 mmHg or >130 mmHg. PaO<60 mmHg, normal PaCO, type I respiratory failure; PaO<60 mmHg, PaCO>50 mmHg, type II respiratory failure.

HCO: includes actual bicarbonate (AB) and standard bicarbonate (SB). AB is the HCO content of plasma measured under actual conditions, with a normal value of 22~27 mmol/L and an average of 24 mmol/L; SB is the HCO content of plasma measured under the conditions of arterial blood 38 ℃, PaCO 40 mmHg, and SaO 100%. Abnormal: If SB>27 mmol/L is metabasic, SB<22 mmol/L is metaacidic.

BE: When the blood is acidic or alkaline, the amount of acid or alkali required to adjust the pH of one liter of blood to 7.4 with alkali or acid under standard conditions (37 ℃, one atmosphere, PCO partial pressure 40 mmHg, Hb fully oxygenated). BE only reflects metabolic changes and is not affected by respiratory factors. Its normal values are: -10~-2 mmol/L for newborns, -7~-1 mmol/L for infants, -4~+2 mmol/L for children, and -3~+3 mmol/L for adults ("-" means insufficient alkali, "+" means excessive alkali).

PaO: The pressure generated by physically dissolved oxygen molecules in arterial blood, with a normal range of 80~100 mmHg. Extreme value: less than 30 mmHg. The reference value for newborns is 40~70 mmHg; the reference value for the elderly is 60 years old>80 mmHg, 70 years old>70 mmHg, 80 years old>60 mmHg, and 90 years old>50 mmHg.

Hb: The normal range for women is 110~150 g/L, and the normal range for men is 120~160 g/L.

Hct: The normal range for women is 35%~45%, and the normal range for men is 40%~50%.

Application of blood gas analyzer

1. Clinical application in infant pneumonia

Pneumonia is a common disease with the highest mortality rate in infants and young children, which seriously threatens the health of children. Children with pneumonia are very prone to hypoxia and acid-base imbalance. Even if the acid-base imbalance is discovered and properly treated clinically, it often depends on the rapid and accurate determination of oxygen partial pressure, carbon dioxide partial pressure and pH in arterial blood.

Blood gas analyzer has very important guiding significance for clinicians to timely grasp and correct the acid-base imbalance of infants and young children with pneumonia, and to judge the respiratory failure of infants and young children with severe pneumonia.

2. Clinical application of patients with severe respiratory system

With the continuous development of clinical medicine, arterial blood gas analysis has become one of the important contents of monitoring critically ill patients. Respiratory diseases, especially critically ill patients, are often accompanied by changes in arterial blood gas such as acid-base imbalance, and the types of acid-base imbalance in different diseases are essentially different. Respiratory diseases can lead to acid-base imbalance and hypoxemia. Arterial blood gas analysis using blood gas analyzer has a direct guiding role in its clinical diagnosis, treatment and prognosis.

3. Application in emergency rescue

When rescuing critically ill patients, blood gas analyzer is one of the most commonly used and very important laboratory examination equipment. Since critically ill patients have different metabolic imbalances, emergency doctors hope to obtain the patient's blood pH, PO2, PCO2, SaO2 and other values in a short time to provide laboratory basis for correcting acid-base imbalance in patients. By collecting blood samples from patients on the spot during rescue and checking on the spot, we strive to obtain relevant data quickly, effectively and accurately.

4. Application in patients with cirrhosis

The degree of hypoxemia in patients with cirrhosis is relatively mild, which is easily masked by liver disease manifestations and is often ignored by forestry doctors. It needs to be detected by blood gas analyzer. Patients with chronic liver disease and cirrhosis are diagnosed with HPS (autosomal recessive genetic disease, which can lead to prolonged bleeding time, albinism, lysosomal colloid deposition and other symptoms) after several years, and a few patients may also develop HPS and its related manifestations in a short period of time. By using a blood gas analyzer to monitor blood oxygen levels, early detection of hypoxemia in patients with cirrhosis can help with timely clinical treatment to improve the quality of life of patients.

5. Application in cardiovascular surgery

During the perioperative period of cardiovascular surgery, the patient's breathing is controlled by a ventilator, the cardiopulmonary function is replaced by an artificial heart-lung machine during extracorporeal circulation, the blood gas acid-base homeostasis is artificially regulated, and the use of low temperature also profoundly affects the blood gas and acid-base homeostasis. Therefore, the management of blood gas and acid-base homeostasis is of special significance to ensure the safety of cardiovascular surgery. The use of POCT blood gas analyzer for dynamic monitoring of blood gas and acid-base homeostasis can accurately and comprehensively reflect the body's cardiopulmonary function and tissue metabolism, which is of great significance for the formulation, implementation and revision of surgical plans.

Advantages of blood gas analyzer

1. Blood gas analyzer shortens the time for emergency detection and reporting

The emergency heart function and renal function detection and reporting time of blood gas analyzer is about 120 minutes, and the detection and reporting time of blood gas analysis, electrolytes, blood sugar, etc. is at least 30 minutes, which is crucial for rescuing emergency critically ill patients.

The rapid blood gas analyzer only takes 2 minutes to issue a report, which shortens the time for emergency detection and reporting, allowing emergency doctors to obtain clinical test results as soon as possible, which is conducive to making decisions quickly and taking intervention measures, so that critically ill patients can receive timely treatment and improve the early diagnosis rate.

2. The blood gas analyzer improves patient satisfaction

The race against time in rescuing critically ill patients is closely related to the time for clinical test reports. Delayed clinical information may miss the best time for patient treatment. The bedside rapid blood gas analyzer, due to its convenient, rapid and accurate characteristics, closely combines the test work with the patient's clinical diagnosis and treatment, and improves the quality of emergency first aid care and the success rate of treatment.

The use of bedside rapid blood gas analyzers in rescuing patients with multiple injuries, heart failure, diabetes, respiratory failure, etc. can timely adjust the treatment plan, ventilator mode and parameters according to the test results, greatly reducing the patient's stay time in the emergency department, reducing the patient crowding in the emergency department, better implementing emergency process management, and improving patient satisfaction.