【Anesthesia hotspot】Blood transfusion threshold and intraoperative coagulation abnormalities

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Transfusion threshold and intraoperative coagulation abnormalities

Case Form: Review case analysis

The patient, male, 69 years old, weighing 70 kg, is planning to undergo another hip replacement

The patient's clinical examination is not specific: blood pressure, 135/81 mmHg (average arterial pressure 95 mmHg; ECG shows sinus bradycardia 58 times/ min, and there are no abnormalities; Chest x-ray is normal; Hemoglobin (Hb) 121 g/L; Other laboratory results were normal

A 20 G arterial catheter is inserted, a 14 G venous pathway is established, a three-chamber central venous catheter is inserted, and Hartmann solution (1 L)

Based on the fact that the patient has stable ischemic heart disease, the minimum Hb is set to 80 g/L, and the anesthesiologist calculates the patient's maximum allowable blood loss (MABL), using the following formula:

MABL =[(Preoperative Hb- lowest acceptable Hb)/preoperative Hb]× body weight (kg) × blood volume (ml/kg)

[（12.

Due to difficult surgical access, the incision needs to be extended

After 2 hours of surgery, the estimated amount of blood loss in the patient is 1300 ml

Over the next 30 minutes, ephedrine was used more frequently to maintain the patient's MAP >70 mmHg

The acetabular cap was reconstructed using a graft bone, mesh grid and acetabular cage, and bleeding

The patient's MAP decreased to 55 mmHg, heart rate increased to 88 beats per minute, and central body temperature dropped to 35.

The test results again showed Hb77g/L and serum lactate 5.

Enter 2 fresh frozen plasma

The patient is admitted to a recovery room

That night, the patient developed chest pain, ecG showed ST segment depression and was asked to be transferred to the CCU of the cardiac intensive care unit, hospitalized in the CCU for 3 days, during which the ECG showed T wave inversion, plasma troponin was elevated, and the diagnosis was subendocardial myocardial infarction

Case discussion

Re-hip replacement surgery is common, with a 10% failure rate observed for the first hip replacement over a 10-year period

The World Health Organization defines Hb<130 g/L as anemia

Preoperative autologous blood donation is effective in reducing allogeneic blood transfusions, but requires efficient organization and planning

Antifibrinolytic therapy

Aprotinin has been successfully applied in orthopedic surgeries, including spine, hip and knee surgeries, and to reduce blood
loss.

Aprotinin reduces allogeneic transfusions and bleeding
by reducing systemic inflammation, reducing fibrinolysis and thrombin production.

Multiple studies have shown that the use of aprotinin in patients with bilateral or re-hip arthroplasty can reduce blood
loss by 25% to 50%.

Aprotinin has thrombosis and side effects on the kidneys and has been of concern
.

A recent prospective randomized controlled study of patients with new high-risk cardiac surgery showed that the mortality rate with aprotinin exceeded the mortality rate
with tranexamic acid or aminocaproic acid.

Although the amount of blood loss in the aprotinin group was greatly reduced, the mortality rate increased
.

Tranexamic acid inhibits plasmolysis by blocking the lysine binding site of plasminogen to fibrin
.

The literature reports that it can reduce blood
loss in 43% to 54% of patients with knee surgery.

For patients undergoing re-hip surgery, the coagulation side effects should be weighed against
the benefits of reduced blood loss during orthopedic surgery before routine use of tranexamic acid.

Intraoperative blood recovery

Red blood cell collection and filtration during surgery, proper red blood cell washing and infusion back infusion is an effective way to reduce allogeneic blood transfusion and avoid adverse consequences
such as infection.

Current research suggests that this method
can be used when the bleeding volume > 1500ml.

Adverse effects include infection and may worsen coagulation abnormalities
.

The patient in this case used a blood collection system to avoid allogeneic blood transfusions and related side effects
.

Transfusion threshold/maximum amount of blood loss allowed in patients with ischemic heart disease

According to the formula first published by Gross, it is useful
to calculate the maximum amount of blood loss allowed for different patients.

Using the patient's initial Hb as the denominator allows for a conservative estimate
of MABL.

In addition, some studies have reported mathematical models
based on different hemoglobin or hematocrit and blood thinning and red blood cell collection during surgery.

Transfusion studies in patients with chronically stable severe illness have provided fairly good forward-looking data on transfusions in severely ill patients
.

The study excluded active bleeding and other acute hemodynamic events
.

The clinical results of the experimental group with a blood transfusion threshold of 70 g/L were not worse
than those of the experimental group with a blood transfusion threshold of 90 g/L.

In the subgroup with a low transfusion threshold, only patients with concomitant ischemic heart disease had poor clinical outcomes
.

MABL
in bleeding patients cannot be inferred from these clinical data and calculated.

Similarly, it is not appropriate
to calculate the transfusion threshold using a hemoglobin-value rigid sleeve in surgery.

Oxygen consumption and utilization in patients with hemodynamic fluctuations and bleeding during surgery is completely different
from that of patients with stable recovery of severe disease.

In transfusion studies in patients with severe disease, poor clinical outcomes in patients with co-ischemic heart disease in a subgroup of low transfusion thresholds were associated
with patient management described in this example.

It is difficult to determine at which point the heart muscle consumes the most oxygen and uptakes, and it can only be improved
by increasing the ability to carry oxygen.

The best conclusion from the current study is

Hb >100g/L: Blood transfusions may not be beneficial
.

● Hb <70g/L: Blood transfusions may be beneficial
.

Between these ranges, whether or not to transfuse depends on the rate of blood loss, laboratory data showing progressive blood loss, and clinical signs of tissue oxygen insufficiency
.

At the beginning of bleeding, the maximum amount of blood loss to be tolerated and the Hb threshold are instructive, but the effect is not ideal for patients who are bleeding continuously
.

The rate of early blood loss, the established risk of perioperative acute coronary syndrome, and the duration and complexity of surgical procedures all prompted us to intervene early to optimize oxygen carrying
.

Intraoperative hypothermia

Intraoperative moderate hypothermia (<1°C) increases blood loss by approximately 16% (4% to 26%), and the risk of blood transfusion increases by 22% (3% to 37%)
.

A large number of important clinical data suggest that maintaining normal intraoperative body temperature reduces blood loss and the need for blood transfusions
.

Chills can increase oxygen consumption, leading to tissue hypoxia and ischemia
of vital organs.

Warm measures in total hip surgery can reduce blood
loss.

Perioperative hypothermia also affects wound healing
.

In this patient, intraoperative hypothermia, which leads to poor clinical outcomes, is the most preventable factor
.

Perioperative coagulation disorders

Hemodilution, hypothermia, component transfusions, and DIC due to persistent bleeding may cause coagulation disorders
.

Whether and when to discontinue antiplatelet and anticoagulant drugs is an important and difficult decision
.

In this case, these problems are highlighted, such as discontinuation of antiplatelet drugs can increase the risk of postoperative myocardial infarction, while continued use can increase the amount of
bleeding.

In specific cases, a multidisciplinary assessment of the risk-to-benefit ratio of different patients is necessary to improve prognosis for perioperative risk reduction
.

Intraoperative and postoperative management of potential or occurring coagulation abnormalities include: (1) visual assessment of microvascular bleeding in surgical fields and laboratory monitoring of coagulation abnormalities; (2) Platelet transfusion; (3) Import fresh frozen plasma; (4) Input cryoprecipitation; (5) The use of drugs to treat excessive bleeding (such as vasopressin, commonly used hemostatic drugs); and (6) recombinant activation of factor
VII.

The Guidelines for the American Association of Anesthesiologists state that for patients with persistent bleeding:

1.
Platelet transfusion is required when the platelet meter < 50×10/L
.

2.
When indir or APTT is elevated, fresh frozen plasma
needs to be transfused.

3.
When the fibrinogen concentration < 80mg/day (2.
3umol/L), it is necessary to infuse the cold precipitate
.

The guidelines also point out that when the above traditional, effective resources are scarce, the recombinant factor VIIa is also a suitable first aid option
.

The coagulation abnormalities described in this example are multifactorial
.

Early management is facilitated by observing the surgical field and communicating
with the surgeon.

Key information

1.
Anemia must be diagnosed and treated
before large elective surgery.

2.
Clarifying the blood transfusion width, the maximum allowable amount of bleeding and the bleeding rate can help guide blood
transfusion.

3.
Intraoperative red blood cell collection can reduce allogeneic blood
transfusions.

4.
Before surgery, measures to maintain normal body temperature during surgery should be considered
.

5.
Abnormal massive bleeding and extensive bleeding during surgery are often early signs
of coagulation abnormalities.

issue

1.
When calculating MABL, what is the result of choosing Hb as the denominator before surgery?

Answer: Conservative estimate of MABL
.

2.
When the amount of blood loss during surgery is estimated, can I use intraoperative red blood cells to collect?

Answer: 1500ml

1.
What is the effect of mild hypothermia (<1 °C) on blood loss during surgery?

Answer: Significantly increased intraoperative blood loss (about 16%)
.

Notes/Kwan Yong

Typography/Meat