[Classical high-scoring literature reading] Under the action of spontaneous breathing, volatile anesthetics are better than propofol to maintain tidal volume and minute ventilation

Volatile anesthetics maintain tidal volume and minute ventilation to a greater degree than propofol under spontaneous respiration MAC-related concepts ①MAC: The lowest alveolar concentration of inhalation anesthetic that can make 50% of patients have no action response to standardized stimulation (such as skin incision), about 1MAC
.

②MAC awake95: The concentration of alveolar gas anesthetic when 95% of patients can open their eyes to simple instructions MACawake = 0.
4 MAC ③ED50 (50% effective dose): the dose that causes 50% of the positive response (quality response) or 50% of the maximal effect (quantity response).
or concentration
.

1.
Background Although general anesthetics inhibit spontaneous breathing, the comprehensive effects of general anesthetics on respiratory function are unclear
.

Objective To investigate the effect of general anesthesia on spontaneous respiration in different types and doses of non-intubated mice
.

2.
Methods Adult C57BL/6J mice were injected with intravenous anesthetics (propofol and etomidate) and inhaled anesthetics (0.
5, 1.
0, 2.
0 MAC/ED50 sevoflurane and isoflurane) to reduce the righting reflex
.

Whole body plethysmography (WBP) was used to measure respiratory parameters without endotracheal intubation
.

At the same time, the changes of respiratory sensitivity to CO2 in patients under general anesthesia were measured
.

The following respiratory parameters were continuously recorded during anesthesia or CO exposure: respiratory rate (FR), tidal volume (TV), minute ventilation (MV), expiratory time (TE), inspiratory time (TI), inspiratory-expiratory Time ratio (I/E) and peak inspiratory frequency
.

3.
Results Sevoflurane or isoflurane at sub-anesthesia concentration of 0.
5MAC increased respiratory rate (FR), tidal volume (TV) and minute ventilation (MV)
.

Under sevoflurane or isoflurane anesthesia, respiratory rate (FR), tidal volume (TV), and minute ventilation (MV) decreased with increasing CO2 concentration
.

Propofol and etomidate cause respiratory depression, manifested as a decrease in respiratory rate (FR), tidal volume (TV), and minute ventilation (MV)
.

During pure oxygen (100% O2) ventilation, the respiratory rate (FR) of propofol and etomidate were 69.
63±33.
44 times/min and 55.
68±64.
42 times/min, respectively
.

In 3% CO2 ventilation, they were 88.
72±34.
51 times/min and 225.
10±59.
82 times/min, respectively
.

In 5% CO2 ventilation, they were 144.
17±63.
25 times/min and 197.
70±41.
93 times/min, respectively
.

Compared with the propofol group, the mice in the etomidate group were more sensitive to CO2
.

Compared with etomidate, sevoflurane and isoflurane at equivalent doses, propofol resulted in a greater reduction in respiratory rate (FR), minute ventilation (MV), and inspiratory-expiratory time ratio (I/E).
big
.

4.
Conclusion The regulation of spontaneous breathing by general anesthesia is different
.

Inhalation anesthetics increase respiratory rate (FR), tidal volume (TV), minute ventilation (MV) at sub-anaesthetic concentrations, while suppressing these respiratory parameters at higher concentrations
.

Propofol inhibited respiratory parameters to a greater extent than etomidate
.

5.
Figure & Table F1.
Comparison of MAC sevoflurane and isoflurane F2.
The effect of sevoflurane on respiratory function is dose-dependent F3.
The effect of isoflurane on respiratory function is dose-dependent F4.
Intravenous anesthetics on breathing in vivo Effects of Response F5F6END