DOI: https://doi.org/10.21203/rs.3.rs-1990178/v1
Objective To investigate the effect of applying pressure-controlled ventalition and volume-guaranteed (PCV-VG) ventilation on intraoperative respiratory mechanics and pulmonary function in patients in the Trendelenburg position during robot-assisted laparoscopic surgery.
Methods Seventy-six patients who underwent robotic-assisted laparoscopic Trendelenburg position from April 2021 to May 2022 at the Affiliated Hospital of Xuzhou Medical University were selected and divided into PCV-VG group (group P ) and VCV group (group V ) using the random number table method. Observed indexes: intraoperative respiratory mechanics parameters such as peak airway pressure (Ppeak ), plateau pressure (Pplat ), pulmonary dynamic compliance (Cdyn), airway resistance(Raw). Respiratory function parameters: SpO2 , PaO2 , PaCO2 , SaO2 and calculate the oxygenation index (OI), alveolar-arterial oxygen partial pressure difference (PA-a DO2 ), intrapulmonary shunt (Qs /Qt ), respiratory index (RI); intraoperative hemodynamic index and postoperative complications.
Results Compared with VCV, PCV-VG, a new ventilation mode, can better ensure the mechanical ventilation effect in patients with prolonged robotic head-down position without affecting hemodynamics, reduce peak airway pressure and plateau pressure, increase dynamic lung compliance, and optimize intraoperative respiratory function in pneumoperitoneum and Trendelenburg position patients with Trendelenburg position duration over 2h.
Conclusion: Compared to VCV, PCV-VG provided lower Ppeak with Pplat and improved Cdyn during robot-assisted laparoscopic Trendelenburg position surgery, better pulmonary oxygenation and gas exchange after pneumoperitoneum duration beyond 2h,better quality of recovery at 24h postoperatively. while there was no significant difference in hemodynamic variables.
In recent years, robotic minimally invasive surgery has become increasingly sophisticated, gradually replacing some traditional open surgeries due to its advantages of less trauma, faster recovery, and clear vision.[1] .It is an epochal change in modern surgery, as it provides high-definition three-dimensional images for the operator, has a range of motion close to that of a human hand and can move more than 360 degrees in a very small incision, making it prevalent in various surgical fields[2] . However, robotic minimally invasive surgery mostly requires artificial creation of the surgical space, which interferes with the patient's respiratory function and poses a great challenge for intraoperative mechanical ventilation[3] . In order to achieve good surgical field exposure, a high level of patient positioning is usually required to facilitate the surgical operation[4] . The Trendelenburg position is widely used in laparoscopic surgery, and this particular position facilitates field exposure by tilting, so it is very common in laparoscopic surgery[5] . Patients undergoing robotic-assisted laparoscopic surgery are often complex and the duration of surgery is generally long. The prolonged pneumoperitoneum and the fixed special position-Trendelenburg position are bound to cause a series of clinical problems for the patient. The movement of the diaphragm to the cephalad caused by abdominal contents and pneumoperitoneum may lead to decreased pulmonary compliance, increased functional residual volume, and exacerbation of V/Q abnormalities[6] . These effects are more severe in patients with chronic lung disease or in the Trendelenburg position[7] . Although intraoperative ventilation with VCV ensures target minute ventilation; constant flow and peak inspiratory pressure (PIP) increase the incidence of barotrauma and lead to uneven gas distribution in the lungs[8] . PCV-VG is a time-cycling, pressure-regulated mode with variable inspiratory flow that allows for preset tidal volumes and is theoretically well suited for the Trendelenburg position Patients[9] . Previous studies have focused on single-lung ventilation, obese patients, and some prone and lateral procedures. Laparoscopic surgery in the Trendelenburg position with a pneumoperitoneum of more than 2h duration has not been studied so far[10] . In this experiment, we intend to study the effect of applying PCV-VG versus VCV ventilation in prolonged Trendelenburg position for robotic-assisted laparoscopy under general anesthesia, and to observe the changes in respiratory mechanics, pulmonary function, hemodynamics and other parameters under these two different ventilation modes to provide a reference for perioperative respiratory management of such patients in clinical work. We hypothesized that PCV-VG could maintain better oxygenation and ventilation, lower Ppeak with Pplat , and higher dynamic lung compliance during prolonged Trendelenburg position laparoscopic surgery.
In recent years, robotic minimally invasive surgery has become increasingly sophisticated, gradually replacing some traditional open surgeries due to its advantages of less trauma, faster recovery, and clear vision.[1] .It is an epochal change in modern surgery, as it provides high-definition three-dimensional images for the operator, has a range of motion close to that of a human hand and can move more than 360 degrees in a very small incision, making it prevalent in various surgical fields[2] . However, robotic minimally invasive surgery mostly requires artificial creation of the surgical space, which interferes with the patient's respiratory function and poses a great challenge for intraoperative mechanical ventilation[3] . In order to achieve good surgical field exposure, a high level of patient positioning is usually required to facilitate the surgical operation[4] . The Trendelenburg position is widely used in laparoscopic surgery, and this particular position facilitates field exposure by tilting, so it is very common in laparoscopic surgery[5] . Patients undergoing robotic-assisted laparoscopic surgery are often complex and the duration of surgery is generally long. The prolonged pneumoperitoneum and the fixed special position-Trendelenburg position are bound to cause a series of clinical problems for the patient. The movement of the diaphragm to the cephalad caused by abdominal contents and pneumoperitoneum may lead to decreased pulmonary compliance, increased functional residual volume, and exacerbation of V/Q abnormalities[6] . These effects are more severe in patients with chronic lung disease or in the Trendelenburg position[7] . Although intraoperative ventilation with VCV ensures target minute ventilation; constant flow and peak inspiratory pressure (PIP) increase the incidence of barotrauma and lead to uneven gas distribution in the lungs[8] . PCV-VG is a time-cycling, pressure-regulated mode with variable inspiratory flow that allows for preset tidal volumes and is theoretically well suited for the Trendelenburg position Patients[9] . Previous studies have focused on single-lung ventilation, obese patients, and some prone and lateral procedures. Laparoscopic surgery in the Trendelenburg position with a pneumoperitoneum of more than 2h duration has not been studied so far[10] . In this experiment, we intend to study the effect of applying PCV-VG versus VCV ventilation in prolonged Trendelenburg position for robotic-assisted laparoscopy under general anesthesia, and to observe the changes in respiratory mechanics, pulmonary function, hemodynamics and other parameters under these two different ventilation modes to provide a reference for perioperative respiratory management of such patients in clinical work. We hypothesized that PCV-VG could maintain better oxygenation and ventilation, lower Ppeak with Pplat , and higher dynamic lung compliance during prolonged Trendelenburg position laparoscopic surgery.
Seventy-six patients, 42 males and 34 females, were selected for elective robot-assisted laparoscopic low head and high foot position at our hospital from April 2021 to May 2022; approval was obtained from the local ethics committee (XYFY2022-KL090-01) and informed consent from each patient, and they were registered with the Chinese Clinical Trials Registry (ChiCTR2200058460). All study participants were American Society of Anesthesiologists class I-III; age ≥ 18 years; BMI ≤ 30 kg/m2 ; The exclusion criteria were as follows: patients with a previous history of severe respiratory disease, asthma, chronic obstructive pulmonary disease, acute lung injury within 3 months preoperatively, acute respiratory distress syndrome, or severe restrictive lung disease; surgery 2 weeks preoperatively and mechanical ventilation; thoracic surgery history; patients with preoperative history of severe neuromuscular disease; those with cognitive impairment; FEV1/FVC < 70%; Patients were also excluded from the study if the surgical approach was changed or if the patient was transferred to the ICU or pneumoperitoneum time < 2 h or > 7 h. Seventy-six patients were randomized into PCV-VG and VCV groups, 38 each, using the randomized number table method.
All participants fasted for 8h and forwent water for 4h before surgery.After admission to the operating room, a monitor was given to connect the Pure oxygen was administered by face mask for 5 minutes. Induction: 0.05mg/kg Midazolam, 0.5ug/kg sufentanil,0.3mg/kg etomidate,0.6mg/kg rocuronium were administered intravenously in sequence. After tracheal intubation, an anesthesia machine (Myriad WATO EX-75 A7) was connected for mechanical ventilation. Ventilation settings: Group P: PCV-VG mode was used, tidal volume (TV) was set at 6-8mL/kg, inspiration-to-expiration ratio (I:E) was 1:1, initial respiratory rate was 12 breaths/min, maximum pressure was set at 40cmH2O, and inhaled oxygen concentration was maintained at 50%, plus PEEP at 5 cmH2O. Group V: VCV mode was used. The parameters were set as in the experimental group. Intraoperative ventilation frequency was adjusted according to PetCO2 and blood gas values, maintaining PetCO2 between 35–45 mmHg and intraoperative pneumoperitoneum fixed at 12 mmHg. Afterwards, ultrasound-guided bilateral transverse abdominal fascial blocks were performed with 20 ml of 0.375% ropivacaine on each side. The patient's position was fixed at 30°of head-down and foot-up position. Pump cis-atracurium 0.3ug/kg/min to maintain muscle relaxation at 1 to 2 TOF values. Adjust the infusion rate of remifentanil according to HR and IBP, and use vasoactive drugs if necessary, so that it fluctuates between ± 20% of the patient's basal value. After the surgical specimen was removed from the body during surgery, sevoflurane was discontinued and replaced with total intravenous anesthesia. Propofol was discontinued when the pneumoperitoneum was evacuated, and manual pulmonary resuscitation was performed using 30cmH2O retension pressure for 30s 5min before discontinuation, and remifentanil was discontinued at the end of the procedure. An analgesic pump (PCA self-administered analgesia) was connected to the intravenous access and the patient was given neostigmine with flumazenil antagonism before exiting the operating room. Extubation: After extubation in the PACU, the patient was placed in a 30-degree semi-prone position with 3 L/min of oxygen by nasal cannula, and was discharged from the PACU and sent back to the ward when the Aldrete score was ≥ 9.
Preoperatively: patient age, gender, height, weight, BMI, ASA classification, smoking history, history of underlying lung disease, relevant comorbidities (diabetes, hypertension), oxygen saturation on admission, blood pressure, heart rate, pre-induction partial pressure of oxygen, and QOR40 scale score at 24h before surgery.
During surgery.①Pplat, Ppeak, PetCO2, Cdyn, Raw of T2− T7 ②SpO2 and PaO2, PaCO2, SaO2 values in arterial blood gas at each time point of T1 -T8 and calculate Qs /Qt, PA−aDO2, OI, RI. ③HR, MAP of T1 -T8 ; ④Intraoperative vasoactive drug use; operative time, anesthesia time, pneumoperitoneum time, intraoperative anesthetic dosage, intraoperative nasopharyngeal temperature, crystal input volume,urine volume, total intake, bleeding volume, blood transfusion volume.(T1: before induction, T2: 10 min after intubation, T3༚20 min after pneumoperitoneum, T4༚1h after pneumoperitoneum, T5༚2h after pneumoperitoneum,T6 ༚3h after pneumoperitoneum, T7༚and 10 minutes after pneumoperitoneum release,T8:20 min after extubation)
Postoperative:①postoperative extubation time (from the end of surgery to the removal of the tracheal tube); ②patient's PACU stay; ③postoperative hospitalization days; ④24-hour postoperative QOR-40 scale score;⑤incidence of postoperative pulmonary complications (postoperative nausea and vomiting, postoperative fever, unplanned oxygenation, mechanical ventilation outside the operating room, respiratory failure, ARDS, pneumonia, pneumothorax).
According to the previous study, the Ppeak at 1h after VCV mode pneumoperitoneum was 27.5 ± 3.6 mmHg. 10% decrease in Ppeak was considered clinically significant. α = 0.05, 1-β = 0.9, using PASS15.0 software, the sample size was 62 cases. Considering 20% shedding rate, the total sample size was 76 cases. SPSS 20.0 statistical software was applied to statistically analyze the data, and the Shapiro-Wilk test was used to determine whether the continuous data obeyed normal distribution, and the Levene test was used for chi-square test; the quantitative data obeying normal distribution were expressed as‾x ± s, and independent sample t-test was used for comparison between groups at the same time point, and repeated measures were used for comparison between groups at different time points.Quantitative data with non-normal distribution were expressed as median (M) and interquartile range (IQR), and Mann-Whitney U test was used for comparison between groups at the same time point, Friedman test was used for comparison between groups at different time points, and Bonferrioni test was used for comparison between two Bonferrioni test was used for comparison; Kruskal-Wallis rank sum test was used for comparison of rank data; test level α = 0.05, P < 0.05 was considered a statistically significant difference.
2.1 Comparison of general information There was no statistically significant difference between the baseline and intraoperative information of the two groups (P > 0.05) see Table 1.
|
PCV-VG (n = 38) |
VCV (n = 38) |
P-value |
|
|---|---|---|---|
|
Age |
58.08 ± 11.281 |
59.13 ± 11.534 |
0.689 |
|
Male / Female |
21/17 |
21/17 |
1.000 |
|
BMI |
23.18 ± 2.52 |
23.35 ± 3.21 |
0.801 |
|
ASA Classification (I/II/III) |
1/33/4 |
1/32/5 |
0.939 |
|
Smoking (Yes/No) |
11/27 |
8/30 |
0.427 |
|
FEV1 /FVC (%) |
78.26 ± 3.438 |
78.82 ± 2.903 |
0.451 |
|
Surgery time (min) |
294.68 ± 39.641 |
284.92 ± 33.344 |
0.249 |
|
Pneumoperitoneum time (min) |
260.61 ± 43.227 |
247.71 ± 39.665 |
0.180 |
|
Anesthesia time (min) |
324.18 ± 43.321 |
319.55 ± 37.616 |
0.620 |
|
Propofol (mg) |
499.08 ± 81.844 |
469.61 ± 91.743 |
0.144 |
|
Rifentanil (mg) |
3.021 ± 0.3206 |
3.047 ± 0.3951 |
0.751 |
|
Phenylephrine (ug) |
120 (0, 340) |
110 (40, 340) |
0.912 |
|
Atropine (mg) |
0 (0, 0) |
0 (0, 0) |
0.740 |
|
Ephedrine (mg) |
0 (0, 3) |
0 (0, 3.75) |
0.846 |
|
Nasopharyngeal temperature (℃) |
36.6 (36.5, 36.7) |
36.6 (36.6, 36.7) |
0.229 |
|
Bleeding volume (ml) |
100 (50, 100) |
70 (50, 120) |
0.611 |
|
Urine volume (ml) |
747.6 ± 328.061 |
683.0 ± 259.791 |
0.344 |
|
Crystal intake (ml) |
1300 (1000, 1625) |
1300 (1000, 1725) |
0.664 |
|
Total intake (ml) |
2000 (1600, 2500) |
1800 (1575, 2425) |
0.613 |
|
Blood transfusion volume (ml) |
0 (0, 0) |
0 (0, 0) |
1.000 |
|
Group |
Indicators |
T2 (10 min after intubation) |
T3 (20 min after pneumoperitoneum) |
T4 (1h after pneumoperitoneum) |
T5 (2h after pneumoperitoneum) |
T6 (3h after pneumoperitoneum) |
T7 (after ten minutes of deflating the abdomen) |
|---|---|---|---|---|---|---|---|
|
PCV-VG |
Ppeak |
14.53 ± 1.109✸➌~➏ |
19.95 ± 2.711✸➋➎➐ |
19.76 ± 2.655✸➋➎➐ |
22.21 ± 3.857✸➋➌➍➐ |
21.18 ± 3.525✸➋➐ |
16.11 ± 2.566✸➌~➏ |
|
VCV |
Ppeak |
16.45 ± 3.804✸➌~➐ |
23.18 ± 3.092✸➋➐ |
24.18 ± 3.563✸➋➐ |
25.08 ± 3.044✸➋➐ |
24.89 ± 3.359✸➋➐ |
18.87 ± 3.314✸➋~➏ |
|
PCV-VG |
Pplat |
14.24 ± 1.460✸➌~➐ |
19.87 ± 2.002✸➋➐ |
19.68 ± 2.015✸➋➐ |
21.16 ± 3.218✸➋➐ |
21.18 ± 2.846✸➋➐ |
15.84 ± 2.488✸➋~➏ |
|
VCV |
Pplat |
16.13 ± 3.060✸➌~➐ |
22.63 ± 3.123✸➋➍~➐ |
23.87 ± 2.988✸➋➐ |
24.84 ± 2.411✸➋➌➐ |
24.34 ± 2.592✸➋➌➐ |
18.13 ± 2.942✸➋~➏ |
|
PCV-VG |
Cdyn |
54.55 ± 2.379✸➌~➐ |
33.34 ± 2.989➋➍➏➐ |
30.05 ± 2.130✸➋➌➐ |
31.58 ± 4.91✸➋➏➐ |
28.32 ± 4.356✸➋➌➎➐ |
48.76 ± 4.346✸➋~➏ |
|
VCV |
Cdyn |
51.50 ± 2.491✸➌~➐ |
32.26 ± 4.831➋➍~➐ |
27.39 ± 3.374✸➋➌➐ |
25.55 ± 3.06✸➋➌➐ |
26.26 ± 2.767✸➋➌➐ |
42.39 ± 6.335✸➋~➏ |
|
PCV-VG |
Raw |
25.00 ± 4.466✸➌~➏ |
28.97 ± 7.607✸➋➐ |
29.74 ± 7.146✸➋➐ |
31.79 ± 6.515✸➋➐ |
29.87 ± 6.30✸➋➐ |
24.61 ± 3.983✸➌~➏ |
|
VCV |
Raw |
19.50 ± 3.343✸➌~➐ |
25.32 ± 5.121✸➋➐ |
26.21 ± 5.974✸➋➐ |
25.132 ± 4.134✸➋➐ |
25.43 ± 4.53✸➋➐ |
21.61 ± 3.695✸➋~➏ |
| Note: Example ➊➋➌➍➎➏➐➑ indicates P < 0.05 compared with T1, T2, T3, T4, T5, T6, T7, T8 ; ✸ indicates P < 0.05 compared to group V or P | |||||||
Compared with the group V, Ppeak, Pplat, and Raw were significantly lower in the group P at the T2 -T7 time points (P < 0.05), and Cdyn was greater in the group P than in the group V at all time points except T3 (P < 0.05). It can be concluded that PCV-VG provided lower Ppeak, Pplat, and higher Raw, Cdyn compared to VCV.
For the group P, Ppeak increased steadily during pneumoperitoneum in the Trendelenburg position, reaching a maximum at T5 which was statistically significant (p < 0.05) compared to T2, T3, T4, T7. However, once resumed in the flat position without pneumoperitoneum (T7 ) was lower than T3 -T6 (p < 0.05) and did not differ from T2 (p > 0.05). During Trendelenburg pneumoperitoneum Pplat was stable, with no statistically significant differences at all time points (p > 0.05), and T7 was lower than T3 -T6 and higher than T2 (p < 0.05). For group V, Ppeak, Pplat remained essentially stable during the Trendelenburg postural pneumoperitoneum, and Ppeak, Pplat were higher at T7 than at T2 (P < 0.05).
The Cdyn in both groups decreased gradually over time overall, with T7 being higher than T3 -T6 and lower than T2 (p < 0.05). In Raw, after pneumoperitoneum and Trendelenburg position both groups showed a sharp decrease in Cdyn, with a decrease of about 38.88% in group P compared to T2 and 37.36% in group V compared to T2. It has been maintained at a low level since then.
Raw values remained stable in both groups during Trendelenburg position, and Raw increased about 15.88% and 29.85% in group P and group V at T3 compared to T2. There was no statistically significant difference between the two groups at each time point of T3 -T6 (P > 0.05), no significant difference between T2 and T7 in the
Group P(P > 0.05), and higher Raw in T7 compared to T2 in the group V(P < 0.05).
|
Ventilation method |
Projects |
T1 (before induction) |
T2 (10 min after intubation) |
T3 (20 min after pneumoperitoneum) |
T4 (1h after pneumoperitoneum) |
T5 (2h after pneumoperitoneum) |
T6 (3h after pneumoperitoneum) |
T7 (after ten minutes of deflating the abdomen) |
T8 (20 min after extubation) |
|---|---|---|---|---|---|---|---|---|---|
|
Group P |
SaO2 (mmhg) |
97.53 ± 1.38 ➋~➐ |
99.41 ± 0.55 ➊➑ |
99.24 ± 0.60 ➊➑ |
99.3 ± 0.53 ➊➑ |
99.5 ± 0.77 ➊➑ |
99.6 ± 0.74 ➊➑ |
99.45 ± 0.67 ➊➑ |
96.56 ± 1.70✸ ➋~➐ |
|
Group V |
97.4 ± 1.67 ➋~➑ |
99.3 ± 0.86 ➊➑ |
98.91 ± 0.83 ➊➎➏➑ |
99.3 ± 0.72 ➊➑ |
99.4 ± 0.67 ➊➌➑ |
99.4 ± 0.48 ➊➌➑ |
99.32 ± 0.62 ➊➑ |
94.05 ± 2.19✸ ➊~➐ |
|
|
Group P |
SPO2 (mmhg) |
97.92 ± 1.12 ➋-➐ |
99.89 ± 0.31 |
99.53 ± 0.69 |
99.39 ± 0.72 |
99.45 ± 0.65 |
99.53 ± 0.65 |
99.66 ± 0.53 |
96.79 ± 1.99✸ |
|
Group V |
97.58 ± 1.24 ➋-➑ |
99.79 ± 0.53 |
99.42 ± 0.76 |
99.32 ± 0.74 |
99.39 ± 0.72 |
99.61 ± 0.64 |
99.71 ± 0.52 |
95.16 ± 2.68✸ |
|
|
Group P |
PaO2 (mmhg) |
92.28 ± 5.05 ➋~➑ |
220.67 ± 35.24➊➑ |
207.84 ± 27.07 ➊➑ |
211.24 ± 34.12 ➊➑ |
220.97 ± 30.0✸ ➊➑ |
220.87 ± 23.05✸ ➊➑ |
213.79 ± 24.10 ➊➑ |
80.81 ± 6.69 ➊~➐ |
|
Group V |
91.16 ± 8.18 ➋~➑ |
217.74 ± 20.68➊➌➍➎➑ |
195.25 ± 30.57 ➊➋➐➑ |
197.39 ± 25.92 ➊➋➐➑ |
196.92 ± 25.3✸ ➊➋➐➑ |
202.28 ± 21.18✸ ➊➐➑ |
221.33 ± 26.63 ➊➌➍➎➏➑ |
81.52 ± 5.65 ➊~➐ |
|
|
Group P |
PaCO2 (mmhg) |
39.13 ± 2.55 ➍~➑ |
38.27 ± 4.36 ➍~➑ |
40.43 ± 4.10 ➍~➑ |
44.91 ± 4.49 ➊➋➌➎➏ |
47.56 ± 4.47✸ ➊➋➌➍➐➑ |
48.53 ± 5.08✸ ➊➋➌➍➐➑ |
43.83 ± 6.45 ➊➋➌➎➏ |
44.00 ± 3.06✸ ➊➋➌➎➏ |
|
Group V |
38.35 ± 2.69 ➌~➑ |
36.93 ± 4.01 ➌~➑ |
41.23 ± 2.84 ➊➋➍➎➏ |
45.21 ± 2.90 ➊➋➌➐➑ |
45.15 ± 3.73✸ ➊➋➌➐➑ |
45.03 ± 5.27✸ ➊➋➌➐➑ |
42.00 ± 1.91 ➊➋➍➎➏ |
41.55 ± 3.82✸ ➊➋➍➎➏ |
|
| Note: Example ➊➋➌➍➎➏➐➑ indicates P < 0.05 compared with T1, T2, T3, T4, T5, T6, T7, T8 ; ✸ indicates P < 0.05 compared to group V or P | |||||||||
SaO2 at T1 -T7 between the two groups have no statistical significance (P > 0.05), and the intraoperative SaO2 values were really stable in group P and group V. Group P had a higher SaO2 10 min after resuming the flat position and deflating the abdomen (P < 0.05). The intraoperative SpO2 was stable, and the SpO2 was slightly higher in group P than in group V 20 min after extubation.
The differences in PaO2 and PaCO2 between the two groups before induction were not statistically significant (P > 0.05), and PCV-VG provided higher PaO2 and PaCO2 than VCV during pneumoperitoneum in the Trendelenburg position only at 2h and 3h after pneumoperitoneum, but these difference disappeared again 10 min after pneumoperitoneum resumed in the flat position.The difference in PaO2 between the two groups at 20 min after extubation was not statistically significant (P > 0.05). However, the PaCO2 in the P group was higher than that in the V group 20 min after extubation, and it was statistically significant (P < 0.05). With the prolongation of pneumoperitoneum in the Trendelenburg position, PaCO2 gradually increased in both groups, and the increase in PCV-VG was slightly greater than that in VCV, however, this difference was not statistically significant even after the withdrawal of the pneumoperitoneum and Trendelenburg position (P > 0.05).
|
Ventilation method |
Projects |
T1 (before induction) |
T2 (10 min after intubation) |
T3 (20 min after pneumoperitoneum) |
T4 (1h after pneumoperitoneum) |
T5 (2h after pneumoperitoneum) |
T6 (3h after pneumoperitoneum) |
T7 (after ten minutes of deflating the abdomen) |
T8 (20 min after extubation) |
|---|---|---|---|---|---|---|---|---|---|
|
Group P |
Oxygenation index OI (mmhg) |
/ |
441.3 ± 70.5 |
415.7 ± 54.14 |
422.5 ± 68.24 |
441.9 ± 60.04✸ |
441.7 ± 46.10✸ |
427.6 ± 48.21 |
/ |
|
Group V |
/ |
435.5 ± 41.37 ➌➍➎ |
390.5 ± 61.15 ➋➐ |
394.8 ± 51.84 ➋➐ |
393.8 ± 50.60✸➋➐ |
404.6 ± 42.35✸ ➐ |
442.7 ± 53.26 ➌➍➎➏ |
/ |
|
|
Group P |
PA−a DO2 (mmhg) |
215.3 ± 6.23 ➋~➑ |
88.0 ± 35.12 ➊➑ |
98.1 ± 27.89 ➊➎➏➑ |
89.1 ± 34.21 ➊➑ |
76.1 ± 30.94✸ ➊➌➑ |
75.9 ± 21.89✸ ➊➌➐➑ |
87.9 ± 24.72 ➊➏➑ |
220.7 ± 7.55 ➊~➐ |
|
Group V |
217.4 ± 8.27 ➋~➑ |
92.6 ± 21.06 ➊➌➑ |
109.7 ± 30.94 ➊➋➐➑ |
102.6 ± 26.55 ➊➐➑ |
103.1 ± 25.94✸➊➐➑ |
97.9 ± 21.63✸ ➊➐➑ |
82.7 ± 26.62 ➊➌➍➎➏➑ |
223.1 ± 6.74 ➊~➐ |
|
|
Group P |
QS /Qt |
0.118 ± 0.003➋~➑ |
0.051 ± 0.020➊➑ |
0.057 ± 0.015 ➊➎➏➑ |
0.052 ± 0.019 ➊➑ |
0.045 ± 0.018✸➊➌➑ |
0.044 ± 0.012✸ ➊➌➐➑ |
0.051 ± 0.014 ➊➏➑ |
0.12 ± 0.004 ➊~➐ |
|
Group V |
0.119 ± 0.004➋~➑ |
0.054 ± 0.012➊➌➑ |
0.063 ± 0.017 ➊➋➐➑ |
0.06 ± 0.015 ➊➐➑ |
0.06 ± 0.014✸ ➊➐➑ |
0.057 ± 0.012✸ ➊➐➑ |
0.049 ± 0.015 ➊➌➍➎➏➑ |
0.121 ± 0.003 ➊~➐ |
|
|
Group P |
RI |
2.343 ± 0.19 ➋~➑ |
0.431 ± 0.236➊➑ |
0.497 ± 0.206 ➊➏➑ |
0.460 ± 0.247 ➊➑ |
0.37 ± 0.20✸ ➊➑ |
0.353 ± 0.142✸ ➊➌➐➑ |
0.43 ± 0.16 ➊➏➑ |
2.757 ± 0.333 ➊~➐ |
|
Group V |
2.411 ± 0.308➋~➑ |
0.438 ± 0.137➊➌➑ |
0.603 ± 0.272 ➊➋➐➑ |
0.547 ± 0.216 ➊➐➑ |
0.549 ± 0.204✸➊➐➑ |
0.5 ± 0.16✸ ➊➐➑ |
0.393 ± 0.17 ➊➌➍➎➏➑ |
2.75 ± 0.257 ➊~➐ |
|
| Note: Example ➊➋➌➍➎➏➐➑ indicates P < 0.05 compared with T1, T2, T3, T4, T5, T6, T7, T8 ; ✸ indicates P < 0.05 compared to group V or P | |||||||||
The differences of PA−aDO2, Qs /Qt, and RI between the two groups before induction were not statistically significant (P > 0.05), 2h and 3h after pneumoperitoneum, the group P provided a higher oxygenation index (P < 0.05). However, this advantage disappeared 10 min after pneumoperitoneum and position resumed. There was no significant difference in OI between the two groups at T2, T3, T4, and T7 (P > 0.05). At T2, PA−aDO2, Qs /Qt, and RI decreased by 59% (57.4%), 56.8% (54.6%), and 81.3% (81.8%) compared with baseline in both groups. Besides,PA−a DO2, Qs/Qt, and RI values were relatively stable in both groups from T3 to T7, with the group P providing lower PA−aDO2, Qs/Qt and RI values at T5 and T6, indicating that PCV-VG provided better pulmonary ventilation, pulmonary gas exchange and reduced intrapulmonary shunts compared with VCV in the type of pneumoperitoneum combined with Trendelenburg position over 2h, but this advantage was maintained only intraoperatively, and it was not reflected after the pneumoperitoneum disappeared and flat position was restored (T7 ) and 20 min after extubation.
|
Ventilation method |
Projects |
T1 (before induction) |
T2 (10 min after intubation) |
T3 (20 min after pneumoperitoneum) |
T4 (1h after pneumoperitoneum) |
T5 (2h after pneumoperitoneum) |
T6 (3h after pneumoperitoneum) |
T7 (after ten minutes of deflating the abdomen) |
T8 (20 min after extubation) |
|---|---|---|---|---|---|---|---|---|---|
|
Group P |
HR (times/minute) |
69.16 ± 6.541 ➋-➐ |
57 ± 9.41 ➊➑ |
52.71 ± 7.66 ➊➑ |
53.97 ± 7.32 ➊➑ |
54.05 ± 7.75 ➊➑ |
53.16 ± 5.48 ➊➑ |
55.37 ± 6.47 ➊➑ |
65.58 ± 7.91 ➋-➐ |
|
Group V |
71.11 ± 3.68 ➋-➑ |
59.53 ± 10.55 ➊➌➏ |
52.87 ± 3.95 ➊➋➐➑ |
54.737 ± 4.76 ➊➑ |
55.447 ± 6.837 ➊➑ |
52.53 ± 4.89 ➊➋➐➑ |
58.24 ± 7.74 ➊➌➏ |
62.92 ± 6.93 ➊➌-➏ |
|
|
Group P |
MAP (mmhg) |
100 ± 7.99 ➋-➐ |
66.00 ± 3.77 ➊➌-➑ |
72.98 ± 4.52 ➊➋➍-➑ |
80.61 ± 8.07 ➊➋➌➑ |
81.74 ± 9.08 ➊➋➌➑ |
83.05 ± 6.99 ➊➋➌➑ |
81.76 ± 9.79 ➊➋➌➑ |
101.89 ± 11.80 ➋-➐ |
|
Group V |
100.55 ± 10.2 ➋-➐ |
65.31 ± 5.96 ➊➌-➑ |
73.86 ± 5.33 ➊➋➍-➑ |
81.55 ± 3.95 ➊➋➌➑ |
81.33 ± 4.88 ➊➋➌➑ |
83.58 ± 4.30 ➊➋➌➑ |
82.37 ± 9.08 ➊➋➌➑ |
103.82 ± 8.10 ➋-➐ |
|
| Note: Example ➊➋➌➍➎➏➐➑ indicates P < 0.05 compared with T1, T2, T3, T4, T5, T6, T7, T8 ; ✸ indicates P < 0.05 compared to group V or P | |||||||||
There were no differences in hemodynamic variables between the two groups. However, due to the change in surgical position, MAP decreased by about 34% (35.6%) in the P and V groups at T2 compared to T1 and increased by about 10.6% (13.1%) in both groups at T3 compared to T2. It can be concluded that all patients in both growere stable in terms of intraoperative hemodynamics.
|
Projects |
PCV-VG |
VCV |
P-value |
|---|---|---|---|
|
Preoperative QOR40 score |
173.57 ± 7.67 |
172.54 ± 7.62 |
0.559 |
|
Postoperative QOR 40 score |
160.11 ± 7.097 |
151.50 ± 5.769 |
< 0.001 |
|
Antagonism time (min) |
7 (5, 9) |
8 (6, 12) |
0.053 |
|
PACU retention time (min) |
36.11 ± 6.600 |
33.53 ± 6.207 |
0.083 |
|
Length of hospitalization (days) |
7.5 (7, 8) |
7 (7, 8) |
0.839 |
|
Postoperative nausea and vomiting (%) |
5 (13.2%) |
4 (10.5%) |
1.000 |
|
Postoperative fever (%) |
2 (5.3%) |
3 (7.9%) |
1.000 |
|
Unplanned oxygen intake (%) |
1 (2.6%) |
1 (2.6%) |
1.000 |
|
Mechanical ventilation outside the operating room (%) |
0 (100%) |
0 (100%) |
༞0.05 |
|
Respiratory failure (%) |
0 (100%) |
0 (100%) |
༞0.05 |
|
ARDS (%) |
0 (100%) |
0 (100%) |
༞0.05 |
|
Pneumonia (%) |
3 (7.9%) |
4 (10.5%) |
༞0.05 |
|
Pneumothorax (%) |
0 (100%) |
0 (100%) |
༞0.05 |
| Note: Quantitative information for normal distribution is expressed as‾ x ± s, quantitative information for non-normal distribution is expressed as median (M) and interquartile range (IQR) | |||
There was no significant difference between the QOR40 scores of the two groups of patients at 24h preoperatively, and the QOR40 score at 24h postoperatively was higher in group P than in group V (P < 0.001).The correlation analysis of QOR40 score 24 hours after operation with age, gender, and pneumoperitoneum time showed that the QOR40 score 24 hours after operation had a good correlation with gender and pneumoperitoneum time (R2 = 0.327 F = 11.667 P < 0.001, see Fig. 1), with women scoring lower (P = 0.013), probably because women are more prone to anxiety. The longer the duration of pneumoperitoneum (P < 0.001), the lower the 24h postoperative QOR40 score. The remaining parameters were not significantly different between the two groups. It can be concluded that PCV-VG ventilation has a better quality of 24h postoperative recovery than VCV ventilation, and there was no significant difference in postoperative complications between the two.
In patients undergoing laparoscopic surgery in the Trendelenburg position, pulmonary function is affected by the movement of the CO2 pneumoperitoneum and abdominal contents against the diaphragm. Subsequent displacement of the diaphragm and mediastinal structures towards the head leads to a decrease in functional residual capacity (FRC) and lung compliance, and an increase in peak inspiratory and plateau pressures. Changes in lung physiology are more affected by pneumoperitoneum than by trendelenburg position[11, 12], so to reduce the interference of intraoperative factors, we fixed the pneumoperitoneum pressure and position angle on the premise of ensuring the surgical field of vision. In VCV, the ventilator provides a constant preset tidal volume, but airway pressure is influenced by lung compliance, patient's intraoperative lung compliance decreases may accompany with the tidal volume vary, especially during the transition from the supine to the Trendelenburg position and during pneumoperitoneum establishment with CO2. It also carries the risk of hypoventilation or hyperventilation[13]. The PCV-VG provides a target tidal volume by decelerating flow, similar to PCV. It compares the Cdyn measured with each breath and adjusts inspiratory pressure to achieve the set tidal volume. Intraoperative depth of anesthesia, muscle relaxation, and surgical maneuvers also alter compliance and resistance[14]. The PCV-VG effectively combines the volume control and pressure limitation ,its lower inspiratory pressure and decelerated flow rate reduce the degree of PIP elevation, which prevents lung injury (Barotraumas) and improves the distribution of inhaled air by minimizing pulmonary atelectasis[15] .
In previous studies focusing on one-lung ventilation in thoracic surgery, special patients such as obese patients, elderly patients, and special positions such as prone, lateral posterior laparoscopy, and Trendelenburg laparoscopy with pneumoperitoneum duration less than 3h, it has been demonstrated that PCV-VG provides lower Ppeak, Pplat and improved Cdyn compared to VCV. There were no significant differences in blood gas analysis parameters between the prone, lateral and Trendelenburg groups[16, 17]. PCV-VG in posterior laparoscopic surgery also reduced dead space ventilation, facilitated CO2 evacuation and shortened postoperative hospital stay[18]. In elderly single lung ventilation, PCV-VG mode was found to reduce airway pressure in open-chest patients compared to VCV, and also reduced neutrophil release, reducing inflammatory response and lung injury[19]. It has also been discovered that at each time point after pneumoperitoneum in the Trendelenburg position, the mean PaO2 levels were significantly higher in the PCV-VG group than in the VCV group[20]. In terms of respiratory mechanics, this experiment did not differ significantly from previous studies. PCV-VG provided lower Ppeak, Pplat and higher Cdyn and Raw. Ppeak reflects the dynamic compliance of the respiratory system and depends on factors such as VT, inspiratory time, endotracheal size and airway resistance[21], and Pplat correlates with static lung compliance[22] .
Our study included patients with pneumoperitoneum duration longer than 3h. There are no similar previous studies in Chinese and foreign studies. It was concluded that PCV-VG did not show the advantages in the first 2h of pneumoperitoneum, but provided a higher oxygenation index, less intrapulmonary shunt, respiratory index and arterial oxygen partial pressure difference compared to VCV after pneumoperitoneum over 2h, however, the differences in these parameters decreased or even did not differ when transferred to the horizontal position. Probably because it was the prior exclusion of patients with a history of pulmonary disease and pulmonary surgery from this experiment, the patients' own physiological conditions were still sufficient to compensate for the adverse physiological changes caused by pneumoperitoneum and position at the beginning of the surgery, and the two groups did not show a large difference. As the duration of surgery increases, this difference slowly becomes apparent, and the advantages of PCV-VG are gradually amplified. However, once these adverse interventions are withdrawn, there is a slow return to a comparatively normal physiological state.
Intraoperative hemodynamics were fairly stable in both groups, The increase in MAP when shifting to a head-down, foot-up position may be related to the redistribution of blood in the circulation due to increased resistance of the body circulation and compression of intra-abdominal organs by intra-abdominal pressure.
PCV-VG had a better quality of postoperative 24h recovery than VCV in terms of postoperative. We did a correlation analysis between QOR40 score and patients' age, gender, and pneumoperitoneum time and found that women had lower quality of recovery at 24h postoperatively than men, and the longer the pneumoperitoneum time, the lower the QOR40 score. No significant differences were found for the remaining complications. This suggests that the benefit of PCV-VG in this group of patients may be limited only to the intraoperative period and that it is challenging to assess and interpret the long-term effects of PCV-VG or VCV on patients. 8 of the 17 publications mentioned multiple postoperative outcome parameters. Only one study reported that PCV-VG reduced patients' ICU and hospital length of stay[23]. Our study included the quality of recovery at 24h postoperatively, yielding a better quality of recovery at 24h postoperatively for PCV-VG. As far as the assessed endpoints are concerned, PCV-VG appears to be a safe technique for ventilation, with no postoperative-related disadvantages so far .
Limitations of this paper.
1. Our study excluded patients who were obese and had poor preoperative lung function. The study found that the return to a flat position in such patients could make it more difficult to counteract hypercapnia with ventilation and oxygenation[24], assuming that these patient groups would benefit from PCV-VG, then the effect of PCV-VG may be underestimated.
2. In this paper, the patient's position was fixed in the Trendelenburg position at 30 degrees and the pneumoperitoneum pressure was fixed at 12 mmHg only due to the exclusion of interfering factors, but in clinical work, different pneumoperitoneum pressures and intraoperative changes in position are sometimes required due to different patient body types. The results of different angular positions and pneumoperitoneum pressures are often not the same.
Overall, intraoperative ventilation using the PCV-VG technique appears to be beneficial, although valid data on the long-term outcome parameters of the different ventilation modes remain to be determined. PCV-VG appears to offer unquestionable clinical advantages. Whether this modality can meet our high expectations for the perioperative patients’ lung protection remains to be determined in future studies.