How do you deal with hypoxemia during one-lung ventilation?

Today is sunny, cloudy and sunny, and finally it's time to turn to the thoracic surgery room! Xiao Wang walked into the 16 operating rooms with a burst of joy .

Today is sunny, cloudy and sunny, and finally it's time to turn to the thoracic surgery room! Xiao Wang walked into the 16 operating rooms with a burst of joy .

The second line cleared his throat: This classmate, you are new here today.

- Classmate Xiao Wang: Huh? emmm.

- Second-line teacher: Baidu? Does this make sense? Open Wutong Medicine, search for hypoxemia, and you can find a satisfactory answer

One-lung ventilation (OLV) is a key technique in thoracic surgery, which can make the lung collapse in the surgical area to define the scope of the lesion, create a clear surgical field, and reduce the mechanical damage of the unresectioned part of the lung, but about 9% during OLV .
Hypoxemia occurs in ~ 27% of patients .

The presence of hypoxemia can significantly increase the risk of perioperative complications such as cognitive impairment, atrial fibrillation, renal failure, and pulmonary hypertension
.

Therefore, how to properly and efficiently manage hypoxemia during OLV has become an important skill that anesthesiologists must master

The presence of hypoxemia can significantly increase the risk of perioperative complications such as cognitive impairment, atrial fibrillation, renal failure, and pulmonary hypertension

01 Causes of OLV Hypoxemia 01 OLV Hypoxemia Causes 01 OLVHypoxemia Causes

Improper position of the bronchial tube

Improper position of the bronchial tube

Incorrect positioning of a double-lumen bronchial catheter is the most common cause of hypoxemia during OLV in thoracic surgery .

Incorrect positioning of a double-lumen bronchial catheter is the most common cause of hypoxemia during OLV in thoracic surgery .

The position of the double-lumen bronchial catheter is too deep or too shallow, the catheter rotates, blocks the opening of the left upper lobe, the catheter enters the right main bronchus or the bronchial opening of the right upper lobe of the lung is blocked, etc.

Studies have shown that even after the patient is positioned and adjusted by the fiberoptic bronchoscope, the probability of double-lumen bronchial catheter displacement can reach 32% and 25%

deal with:

When OLV occurs in one-lung ventilation , the improper position of the double-lumen bronchial catheter or bronchial occluder should be excluded first
.

If the bronchial catheter or bronchial occluder is displaced, it can be adjusted to the correct position under bright vision of the bronchoscope

When OLV occurs in one-lung ventilation , the improper position of the double-lumen bronchial catheter or bronchial occluder should be excluded first

Abnormal Respiratory Physiology Abnormal Respiratory Physiology Abnormal Respiratory Physiology

There are many factors that can affect intrapulmonary shunt during OLV , resulting in imbalance of ventilation / flow (V/Q)ratio, including circulatory factors, continuous perfusion of the non-ventilated lung, insufficient expansion of the ventilated lung, general anesthesia, patient position, etc.

.

There are many factors that can affect intrapulmonary shunt during OLV , resulting in imbalance of ventilation / flow (V/Q)ratio, including circulatory factors, continuous perfusion of the non-ventilated lung, insufficient expansion of the ventilated lung, general anesthesia, patient position, etc.

.

1.
Circulation factor

1.
Circulation factor

Since blood flow to the right and left lungs accounts for 55% and 45% of cardiac output, respectively , the incidence of hypoxemia is higher during right lung surgery
.

Since blood flow to the right and left lungs accounts for 55% and 45% of cardiac output, respectively , the incidence of hypoxemia is higher during right lung surgery
.

The disappearance of negative thoracic pressure after thoracotomy, the reduction of blood return to the heart, the operation compression, hypovolemia, arrhythmia and other factors can reduce the cardiac output and affect the V/Q
.

The disappearance of negative thoracic pressure after thoracotomy, the reduction of blood return to the heart, the operation compression, hypovolemia, arrhythmia and other factors can reduce the cardiac output and affect the arrhythmia V/Q
.

2.
Ventilation

2.
Ventilation

During OLV , the collapse of the non-ventilated lung resulted in a sudden decrease in the alveolar ventilation area, but the pulmonary blood flow did not decrease accordingly
.

During OLV , the collapse of the non-ventilated lung resulted in a sudden decrease in the alveolar ventilation area, but the pulmonary blood flow did not decrease accordingly
.

All of the above can lead to the reduction of V/Q in both lungs after thoracotomy , which further leads to the occurrence of intrapulmonary shunt
.

All of the above can lead to the reduction of V/Q in both lungs after thoracotomy , which further leads to the occurrence of intrapulmonary shunt
.

Among them, the intrapulmonary shunt flow on the non-ventilated side can increase to 40%~50% , and the intrapulmonary shunt is the most serious in the first 20~30 minutes of OLV , but with the initiation of hypoxic pulmonary vasoconstriction (HPV)  Oxygenated venous blood can be gradually relieved, and the intrapulmonary shunt is reduced to 20%-25% .

Among them, the intrapulmonary shunt flow on the non-ventilated side can be increased to 40%-50% , and the intrapulmonary shunt is the most serious within the first 20-30 minutes of OLV , but with the initiation of hypoxic pulmonary vasoconstrictor (HPV)  , the pulmonary shunt is not affected .
Oxygenated venous blood can be gradually relieved, and intrapulmonary shunt is reduced to 20%-25% .

In addition, OLV causes different degrees of damage to the ventilated and non-ventilated lungs, which not only affects the oxygenation of patients during surgery, but also increases postoperative pulmonary complications
.

In addition, OLV causes different degrees of damage to the ventilated and non-ventilated lungs, which not only affects the oxygenation of patients during surgery, but also increases postoperative pulmonary complications
.

3.
General anesthesia and body position

3.
General anesthesia and body position

The V/Q of both lungs did not change much
in the lateral decubitus position in the awake state .
In the lateral decubitus position after general anesthesia, the mechanical ventilation mode can cause good ventilation in the upper lung but insufficient blood flow and increase V/Q ; poor ventilation in the lower lung but good blood perfusion, decrease V/Q and increase ineffective ventilation
.

The V/Q of both lungs did not change much
in the lateral decubitus position in the awake state .
In the lateral decubitus position after general anesthesia, the mechanical ventilation mode can cause good ventilation in the upper lung but insufficient blood flow and increase V/Q ; poor ventilation in the lower lung but good blood perfusion, decrease V/Q and increase ineffective ventilation
.

deal with:

deal with:

First, enhance the understanding of the changes in the related pathophysiological processes before and after anesthesia.
Combine the patient's preoperative pulmonary function, intraoperative medication, depth of anesthesia, respiration and circulation, etc.
, to increase the concentration of inhaled oxygen, and adopt individualized mechanical ventilation modes, including ventilation.
Side positive end-expiratory pressure (PEEP ), non-pulmonary ventilation side continuous positive airway pressure (CPAP ),
etc.

First, enhance the understanding of the changes in the related pathophysiological processes before and after anesthesia.
Combine the patient's preoperative pulmonary function, intraoperative medication, depth of anesthesia, respiration and circulation, etc.
, to increase the concentration of inhaled oxygen, and adopt individualized mechanical ventilation modes, including ventilation.
Side positive end-expiratory pressure (PEEP ), non-pulmonary ventilation side continuous positive airway pressure (CPAP ),
etc.

Hypoxic pulmonary vasoconstriction (HPV) is inhibited

Hypoxic pulmonary vasoconstriction (HPV) is inhibited Hypoxic pulmonary vasoconstriction(HPV)is inhibited

HPV refers to a protective compensatory response of the body's own pulmonary vasoconstriction and increased pulmonary vascular resistance after the decrease in alveolar oxygen partial pressure
.

HPV refers to a protective compensatory response of the body's own pulmonary vasoconstriction and increased pulmonary vascular resistance after the decrease in alveolar oxygen partial pressure
.

HPV manifests as pulmonary vasoconstriction in alveolar hypoxic areas, resulting in increased pulmonary artery resistance and reduced blood flow, allowing blood to flow to well-ventilated areas, thereby improving V/Q imbalance and reducing intrapulmonary shunting
.

HPV manifests as pulmonary vasoconstriction in alveolar hypoxic areas, resulting in increased pulmonary artery resistance and reduced blood flow, allowing blood to flow to well-ventilated areas, thereby improving V/Q imbalance and reducing intrapulmonary shunting
.

Many factors, such as anesthetics, vasodilators, acid-base imbalance, temperature, disease state, and lung manipulation, may affect HPV mechanisms in the non-ventilated lung
.
HPV is inhibited by many drugs used during anesthesia , such as sodium nitroprusside, nitric oxide (NO) , calcium channel blockers, nitrates, beta2 -agonists, inhalation anesthetics,
etc.

Many factors, such as anesthetics, vasodilators, acid-base imbalance, temperature, disease state, and lung manipulation, may affect HPV mechanisms in the non-ventilated lung
.
HPV is inhibited by many drugs used during anesthesia , such as sodium nitroprusside, nitric oxide (NO) , calcium channel blockers, nitrates, beta2 -agonists, inhalation anesthetics,
etc.

Intravenous anesthetics and opioid analgesics have little effect on HPV .
All inhalation anesthetics inhibited HPV in a dose-dependent manner , but compared with enflurane and halothane, isoflurane, desflurane, and sevoflurane had weaker inhibitory effects on HPV , and at ≤1 MAC , their effects were similar to those of halothane.
Intravenous anesthetics are similar .

Intravenous anesthetics and opioid analgesics have little effect on HPV .
All inhalation anesthetics inhibited HPV in a dose-dependent manner , but compared with enflurane and halothane, isoflurane, desflurane, and sevoflurane had weaker inhibitory effects on HPV , and at ≤1 MAC , their effects were similar to those of halothane.
Intravenous anesthetics are similar .

deal with:

deal with:

The effect of HPV can be enhanced by drugs to reduce shunt and improve oxygenation during OLV .
Studies have shown that during OLV .

The effect of HPV can be enhanced by drugs to reduce shunt and improve oxygenation during OLV .
Studies have shown that during OLV .

▪Intravenous amitrin combined with NO inhalation can improve oxygenation under the condition of total intravenous anesthesia .

▪Intravenous amitrin combined with NO inhalation can improve oxygenation under the condition of total intravenous anesthesia .

▪ Intraoperative intravenous use of dexmedetomidine can reduce the inflammatory response caused by OLV and improve the oxygenation of patients during intraoperative OLV .

▪ Intraoperative intravenous use of dexmedetomidine can reduce the inflammatory response caused by OLV and improve the oxygenation of patients during intraoperative OLV .

▪The addition of dexmedetomidine to the epidural space can improve the oxygenation of patients undergoing thoracotomy and reduce the amount of intraoperative anesthesia and analgesia
.

▪The addition of dexmedetomidine to the epidural space can improve the oxygenation of patients undergoing thoracotomy and reduce the amount of intraoperative anesthesia and analgesia
.

▪ Inhalation of iloprost during OLV can selectively dilate the blood vessels of the ventilated lung and increase the blood perfusion of the ventilated lung .

▪ Inhalation of iloprost during OLV can selectively dilate the blood vessels of the ventilated lung and increase the blood perfusion of the ventilated lung .

Intraoperative acute pulmonary embolism

intraoperative acute pulmonary embolism

When hypoxemia occurs during OLV in patients with thoracic trauma , after excluding phlegm embolism blocking the airway and other acute respiratory tract obstruction, if the cause cannot be found, and the cause is not found, accompanied by decreased blood pressure, sinus tachycardia or new right heart Pulmonary embolism should be considered in the presence of dysfunctional ECG changes and circulatory and respiratory changes such as decreased end-tidal carbon dioxide
.

When hypoxemia occurs during OLV in patients with thoracic trauma , after excluding phlegm embolism blocking the airway and other acute respiratory tract obstruction, if the cause cannot be found, and the cause is not found, accompanied by decreased blood pressure, sinus tachycardia or new right heart Pulmonary embolism should be considered in the presence of dysfunctional ECG changes and circulatory and respiratory changes such as decreased end-tidal carbon dioxide
.

Pulmonary function before surgery

Preoperative pulmonary function status Preoperative pulmonary function status Preoperative pulmonary function status

Lesions in the ventilated lung itself may lead to hypoxemia during OLV  .
It should be noted, however, that not all measures of lung function are reliable .

Lesions in the ventilated lung itself may lead to hypoxemia during OLV  .
It should be noted, however, that not all measures of lung function are reliable .

Chronic airflow obstruction can lead to the formation of endogenous PEEP in the ventilated lung due to alveolar hyperventilation , which may improve oxygenation in patients during OLV .
When the non-ventilated lung is severely diseased, preoperative blood flow to this lung may be reduced, resulting in a relatively reduced shunt during OLV , thereby improving oxygenation .

Chronic airflow obstruction can lead to the formation of endogenous PEEP in the ventilated lung due to alveolar hyperventilation , which may improve oxygenation in patients during OLV .
When the non-ventilated lung is severely diseased, preoperative blood flow to this lung may be reduced, resulting in a relatively reduced shunt during OLV , thereby improving oxygenation .

02 Treatment of hypoxemia with one-lung ventilation

02 Treatment of One Lung Ventilation Hypoxemia02 Treatment of One Lung Ventilation Hypoxemia02 Treatment of One LungVentilation Hypoxemia

Once hypoxemia occurs during OLV  , it should be dealt with in time.
The following steps can be followed:

Once hypoxemia occurs during OLV  , it should be dealt with in time.
The following steps can be followed:

( 1 ) Reconfirm the position of the double-lumen tube and the bronchial blocker with a fiberoptic bronchoscope
.

( 1 ) Reconfirm the position of the double-lumen tube and the bronchial blocker with a fiberoptic bronchoscope
.

( 2 ) Use bronchoscopy to confirm whether there is secretion in the catheter.
If there is a large amount of secretion, suction should be performed in time
.

( 2 ) Use bronchoscopy to confirm whether there is secretion in the catheter.
If there is a large amount of secretion, suction should be performed in time
.

( 3 ) Differential diagnosis of the presence of bronchospasm, if so, corresponding treatment should be carried out in time
.

( 3 ) Differential diagnosis of the presence of bronchospasm, if so, corresponding treatment should be carried out in time
.
diagnosis

( 4 ) Adjust FiO2=1.
0
.

( 4 ) Adjust FiO2=1.
0
.

( 5 ) Give CPAP 5-10cmH2O to the non-ventilated side lung , but it is not recommended for thoracoscopic surgery .

( 5 ) Give CPAP 5-10cmH2O to the non-ventilated side lung , but it is not recommended for thoracoscopic surgery .

( 6 ) During the one-lung ventilation process, the ventilated lung should be inflated by intermittent manual control to ensure that the airway pressure should reach 30 cmH2O when the lung is inflated
.
But it should be used with caution in patients with pulmonary bullae
.

( 6 ) During the one-lung ventilation process, the ventilated lung should be inflated by intermittent manual control to ensure that the airway pressure should reach 30 cmH2O when the lung is inflated
.
But it should be used with caution in patients with pulmonary bullae
.

( 7 ) If necessary, under the premise of not affecting the operation, perform intermittent manual ventilation on the operating side of the lung
.

( 7 ) If necessary, under the premise of not affecting the operation, perform intermittent manual ventilation on the operating side of the lung
.

( 8 ) If necessary, the non-ventilating pulmonary artery can be temporarily blocked
.
In the case of pneumonectomy, the non-ventilating pulmonary artery should be ligated as soon as possible
.

( 8 ) If necessary, the non-ventilating pulmonary artery can be temporarily blocked
.
In the case of pneumonectomy, the non-ventilating pulmonary artery should be ligated as soon as possible
.

In addition, if you encounter refractory hypoxemia that cannot be improved by the above methods, you can only resort to the ultimate weapon - extracorporeal membrane oxygenation (ECMO) , which can provide patients with a satisfactory oxygenation state
.

In addition, if you encounter refractory hypoxemia that cannot be improved by the above methods, you can only resort to the ultimate weapon - extracorporeal membrane oxygenation (ECMO) , which can provide patients with a satisfactory oxygenation state
.

references

references

[1] Deng Huimin ,  Feng Di ,  Lv Xin .
  The mechanism and prevention strategies of hypoxemia during one-lung ventilation [J].
  Journal of Clinical Anesthesiology , 2020, 36(12): 1235-1238.

[1] Deng Huimin ,  Feng Di ,  Lv Xin .
  The mechanism and prevention strategies of hypoxemia during one-lung ventilation [J].
  Journal of Clinical Anesthesiology , 2020, 36(12): 1235-1238.
[1] Deng Huimin ,  Feng Di ,  Lv Xin .
  Mechanisms and prevention strategies of hypoxemia during one-lung ventilation [J].
  Journal of Clinical Anesthesiology , 2020, 36(12): 1235-1238.

[2] Deng Xiaoming ,  Yao Shanglong ,  Yu Buwei ,  et al .
  Modern Anesthesiology ( 5th Edition) [M].
  People's Health Publishing House , 2020.

[2] Deng Xiaoming ,  Yao Shanglong ,  Yu Buwei ,  et al .
  Modern Anesthesiology ( 5th Edition) [M].
  People's Health Publishing House , 2020.
[2] Deng Xiaoming ,  Yao Shanglong ,  Yu Buwei ,  et al .
  Modern Anesthesiology ( 5th edition) [M].
  People's Health Publishing House , 2020.
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