Ventilatory effects of laparoscopic cholecystectomy

Comparison between gas insufflation and gasless techniques for endoscopic transaxillary thyroidectomy

Objective

This study aimed to compare clinical outcomes and prognosis of endoscopic thyroidectomy via axillary approach using insufflation and gasless methods.

Methods

Retrospective analysis included patients undergoing endoscopic thyroidectomy at our institution from June 2022 to October 2023. Patients were categorized into insufflation and gasless groups. Analysis compared surgical time, blood loss, drainage volume, tube removal time, hospital stay, complications, pain score, and incision satisfaction.

Results

73 patients (48 insufflation, 25 gasless) were analyzed. Insufflation technique showed significantly superior outcomes: shorter surgery duration, reduced drainage volume, earlier tube removal, shorter hospital stay, and higher incision satisfaction (all P < 0.05). Postoperative pain (VAS) was lower in insufflation group on first day, but no significant difference on seventh day. No significant differences in blood loss or complications were observed.

Conclusion

Insufflation technique offers advantages over gasless method including shorter operation time, reduced drainage, earlier tube removal, and shorter hospital stays, with comparable outcomes in pain and incision satisfaction.

Temporal Changes in Ventilator Settings in Patients With Uninjured Lungs: A Systematic Review

In patients with uninjured lungs, increasing evidence indicates that tidal volume (VT) reduction improves outcomes in the intensive care unit (ICU) and in the operating room (OR). However, the degree to which this evidence has translated to clinical changes in ventilator settings for patients with uninjured lungs is unknown. To clarify whether ventilator settings have changed, we searched MEDLINE, Cochrane Central Register of Controlled Trials, and Web of Science for publications on invasive ventilation in ICUs or ORs, excluding those on patients <18 years of age or those with >25% of patients with acute respiratory distress syndrome (ARDS). Our primary end point was temporal change in VT over time. Secondary end points were changes in maximum airway pressure, mean airway pressure, positive end-expiratory pressure, inspiratory oxygen fraction, development of ARDS (ICU studies only), and postoperative pulmonary complications (OR studies only) determined using correlation analysis and linear regression. We identified 96 ICU and 96 OR studies comprising 130,316 patients from 1975 to 2014 and observed that in the ICU, VT size decreased annually by 0.16 mL/kg (-0.19 to -0.12 mL/kg) (P < .001), while positive end-expiratory pressure increased by an average of 0.1 mbar/y (0.02-0.17 mbar/y) (P = .017). In the OR, VT size decreased by 0.09 mL/kg per year (-0.14 to -0.04 mL/kg per year) (P < .001). The change in VTs leveled off in 1995. Other intraoperative ventilator settings did not change in the study period. Incidences of ARDS (ICU studies) and postoperative pulmonary complications (OR studies) also did not change over time. We found that, during a 39-year period, from 1975 to 2014, VTs in clinical studies on mechanical ventilation have decreased significantly in the ICU and in the OR.

The Effects of Positive End-Expiratory Pressure at Different Levels on Postoperative Respiration Parameters in Patients Undergoing Laparoscopic Cholecystectomy

Purpose/Aim of the study: We investigated the effects of different positive end-expiratory pressure (PEEP) levels on postoperative respiration parameters in patients undergoing laparoscopic cholecystectomy.

MATERIALS AND METHODS

One hundred and five consecutive patients were randomly divided to three groups (n = 35, for each group). Group I did not receive PEEP whereas group II received PEEP as 5 cmH₂O and group III received PEEP as 8 cm H₂O. Measurements with spirometer were taken 1 hour before the operation (T₁) and, 1 (T₂), 6 (T₃), and 24 hours (T₄) after extubation by an anesthetist. Forced expiratory volume (FEV₁), forced vital capacity (FVC), and peak expiratory flow (PEF) were recorded.

RESULTS

Group I had higher FVC values measured at T₂ time point compared with other groups (p < 0.05, for both groups). There was a statistically significant difference between group I and group III in terms of the FVC values measured at T₃ and T₄ time points (p = 0.05 and p < 0.05, retrospectively). A statistical difference was found between group I and group II in terms of FEV₁ measured at T₂ time point (p < 0.05). Group I had higher FEV₁ values measured at T₃ and T₄ time points compared to group III (p = 0.05, P<0.05; respectively). Group III had lower PEF values measured at T₄ time point compared to group I and II (p < 0.05).

CONCLUSIONS

We concluded that PEEP with 5 or 8 cmH₂O has negative effects on lung function tests measured with spirometer during postoperative 1^st, 6^th, and 24^th hours in patients underwent elective laparoscopic cholecystectomy.

Respiratory function during anesthesia: effects on gas exchange

Anaesthesia causes a respiratory impairment, whether the patient is breathing spontaneously or is ventilated mechanically. This impairment impedes the matching of alveolar ventilation and perfusion and thus the oxygenation of arterial blood. A triggering factor is loss of muscle tone that causes a fall in the resting lung volume, functional residual capacity. This fall promotes airway closure and gas adsorption, leading eventually to alveolar collapse, that is, atelectasis. The higher the oxygen concentration, the faster will the gas be adsorbed and the aleveoli collapse. Preoxygenation is a major cause of atelectasis and continuing use of high oxygen concentration maintains or increases the lung collapse, that typically is 10% or more of the lung tissue. It can exceed 25% to 40%. Perfusion of the atelectasis causes shunt and cyclic airway closure causes regions with low ventilation/perfusion ratios, that add to impaired oxygenation. Ventilation with positive end-expiratory pressure reduces the atelectasis but oxygenation need not improve, because of shift of blood flow down the lung to any remaining atelectatic tissue. Inflation of the lung to an airway pressure of 40 cmH2O recruits almost all collapsed lung and the lung remains open if ventilation is with moderate oxygen concentration (< 40%) but recollapses within a few minutes if ventilation is with 100% oxygen. Severe obesity increases the lung collapse and obstructive lung disease and one-lung anesthesia increase the mismatch of ventilation and perfusion. CO2 pneumoperitoneum increases atelectasis formation but not shunt, likely explained by enhanced hypoxic pulmonary vasoconstriction by CO2. Atelectasis may persist in the postoperative period and contribute to pneumonia.

Deep sedation in natural orifice transluminal endoscopic surgery (NOTES): a comparative study with dogs

BACKGROUND

Natural orifice transluminal endoscopic surgery (NOTES) has been mostly performed with the animal under general and inhalational anesthesia (IA-NOTES). To date, NOTES using propofol sedation (PS-NOTES) has not been investigated. This study aimed to assess the feasibility and safety of PS-NOTES for transgastric oophorectomy with carbon dioxide insufflation and to compare its success rates with those of conventional IA-NOTES.

METHODS

In this prospective randomized study, NOTES oophorectomy was performed for 19 female dogs randomized to two conditions: PS (study group) and IA (control group). Sedation success rates (ability to visualize and resect ovaries without converting to IA), operative success rates (ability to resect and retrieve both ovaries in full using only NOTES), and vital parameters including hemodynamic and respiratory changes were documented.

RESULTS

In the PS-NOTES group (n = 9), the sedation success rate was 100 %. The operative success rate was 67 % (6 of 9 animals) compared with 80 % (8 of 10 animals) in the IA-NOTES group. No purposeful movement occurred during surgical manipulation and no respiratory or cardiovascular complications in occurred the PS group. Heart rate (HR) and end-tidal carbon dioxide (ETCO(2)) were significantly higher in the PS group than in the IA group. Blood pressure (BP) was significantly higher in the PS group only during the middle part of the procedure. Only mild respiratory depression was noted in the PS group, as indicated by elevated but acceptable ETCO(2). Elevations in BP and HR are thought to be related to elevated CO(2) but did not appear to have an adverse impact on the course of the procedure. Recovery was uneventful for all the animals.

CONCLUSION

The use of PS-NOTES appears to be feasible, resulting in outcomes comparable with those for IA in dogs. Further studies are needed to determine the applicability of this concept in human NOTES.

Contribution of large pig for renal ischemia-reperfusion and transplantation studies: the preclinical model

Animal experimentation is necessary to characterize human diseases and design adequate therapeutic interventions. In renal transplantation research, the limited number of in vitro models involves a crucial role for in vivo models and particularly for the porcine model. Pig and human kidneys are anatomically similar (characterized by multilobular structure in contrast to rodent and dog kidneys unilobular). The human proximity of porcine physiology and immune systems provides a basic knowledge of graft recovery and inflammatory physiopathology through in vivo studies. In addition, pig large body size allows surgical procedures similar to humans, repeated collections of peripheral blood or renal biopsies making pigs ideal for medical training and for the assessment of preclinical technologies. However, its size is also its main drawback implying expensive housing. Nevertheless, pig models are relevant alternatives to primate models, offering promising perspectives with developments of transgenic modulation and marginal donor models facilitating data extrapolation to human conditions.

Beneficial effects of high positive end-expiratory pressure in lung respiratory mechanics during laparoscopic surgery

BACKGROUND

The effect of neuromuscular blockade (NMB) and positive end-expiratory pressure (PEEP) on the elastic properties of the respiratory system during pneumoperitoneum (PnP) remains a controversial subject. The main objective of the present study was to evaluate the effects of NMB and PEEP on respiratory mechanics.

METHODS

We performed a dynamic analysis of respiratory mechanics in patients subjected to PnP. Twenty-one patients underwent cholecystectomy videolaparoscopy and total intravenous anesthesia. The respiratory system resistance (R(RS)), pulmonary elastance (E(P)), chest wall elastance (E(CW)), and respiratory system elastance (E(RS)) were computed via the least squares fit technique using an equation describing the motion of the respiratory system, which uses primary signs such as airway pressure, tidal volume, air flow, and esophageal pressures. Measurements were taken after tracheal intubation, PnP, NMB, establishment of PEEP (10 cmH2O), and PEEP withdrawal [zero end-expiratory pressure (ZEEP)].

RESULTS

PnP significantly increased E(RS) by 27%; both E(P) and E(CW) increased 21.3 and 64.1%, respectively (P < 0.001). NMB did not alter the respiratory mechanic properties. Setting PEEP reduced E(RS) by 8.6% (P < 0.05), with a reduction of 10.9% in E(P) (P < 0.01) and a significant decline of 15.7% in R(RS) (P < 0.05). These transitory changes in elastance disappeared after ZEEP.

CONCLUSIONS

We concluded that the 10 cmH2O of PEEP attenuates the effects of PnP in respiratory mechanics, lowering R(RS), E(P), and E(RS). These effects may be useful in the ventilatory approach for patients experiencing a non-physiological increase in IAP owing to PnP in laparoscopic procedures.

Increased carbon dioxide absorption during retroperitoneal laparoscopy

BACKGROUND

Retroperitoneoscopy for renal surgery is now a common procedure. We compared carbon dioxide absorption in patients undergoing retroperitoneoscopy for adrenal or renal surgery with that of patients undergoing laparoscopic cholecystectomy.

METHODS

We measured carbon dioxide elimination with a metabolic monitor in 30 anaesthetized patients with controlled ventilation, undergoing retroperitoneoscopy (n=10), laparoscopy (n=10) or orthopaedic surgery (n=10).

RESULTS

Carbon dioxide production increased by 38, 46 and 63% at 30, 60 and 90 min after insufflation (P<0.01) in patients having retroperitoneoscopy. Carbon dioxide production (mean (SD)) increased from 92 (21) to 150 (43) ml x min(-1) m(-2) 60-90 min after insufflation and remained increased after the end of insufflation. During laparoscopy, V(.)(CO(2)) increased less (by 15%) (P<0.05 compared with retroperitoneoscopy) and remained steady throughout the procedure.

CONCLUSION

Retroperitoneal carbon dioxide insufflation causes more carbon dioxide absorption than intraperitoneal insufflation, and controlled ventilation should be increased if hypercapnia should be avoided.

Pigs are not a reliable experimental model in the study of the haemodynamic and respiratory effects of CO2 pneumoperitoneum

BACKGROUND

Haemodynamic and respiratory effects of a CO2 pneumoperitoneum (intra-abdominal pressure = 12 mmHg) associated to a head-up position(15 degrees ) were studied in 20 pigs using a Swan-Ganz catheter and the Single Breath Test for CO2. The pneumoperitoneum induced a moderate rise in mean arterial pressure (+17%) (P<0.001) without any variation in heart rate, cardiac output and systemic vascular resistances.

RESULTS

The following respiratory effects were observed: an increase in PaCO2 (+20%) (P<0.001), PE'CO2 (+31%) (P<0.001), expired volume of CO2 (+28%) (P<0.001), arterial to end-tidal CO2 gradient (+80%) (P<0.001) and alveolar dead space (+40%) (P<0.001) occured. Alveolar ventilation remained stable. Finally and contrary to healthy human patient, intraperitoneal CO2 insufflation in pig induced slight haemodynamic changes and major respiratory modifications.

CONCLUSION

Thus, our data do not support the conclusion that the pig is a reliable experimental model for studying the pathophysiology of CO2 pneumoperitoneum-induced changes in haemodynamic and respiratory parameters, in human patients.

Retroperitoneoscopy versus laparoscopy in piglets: ventilatory and thermic repercussions

BACKGROUND/PURPOSE

Endoscopic surgery of the retroperitoneal space in children is developing. During preliminary clinical experience, the authors were surprised by the differences observed in comparison with laparoscopic pneumpoeritoneum (PNOP); retropneumpoeritoneum (RPNOP) seemed to have less ventilatory repercussions.

METHODS

The authors therefore undertook a study on animal models. Six suckling pigs, newly weaned, each weighing 10 kg successively underwent, at 8-day intervals and in random sequence, a right RPNOP with kidney and vena cava dissection, with insufflation of CO2 at 10 mm Hg of pressure and a PNOP with the same pressure of 10 mm Hg.

RESULTS

P(ET)CO2 increased during PNOP, and it remained stable during during RPNOP (P = .035). The ventilatory peak airway pressures (PawP) increased during PNOP, but were not modified during RPNOP (P = .0001). Temperature decreased with time (P = .0001) without difference between the two procedures (P = .34).

CONCLUSIONS

RPNOP was not associated with any adverse effects on the ventilation despite the insufflation pressure of 10 mm Hg, which allowed a satisfactory working area to be created. Operations by RPNOP could be developed in children with fewer respiratory repercussions than those observed during laparoscopy at an equivalent level of pressure.

Intrathoracic and pulmonary blood volume during CO2-pneumoperitoneum in humans

BACKGROUND

Induction of CO2-pneumoperitoneum may have significant effects on systemic and pulmonary haemodynamics. We hypothesized that intrathoracic (ITBV) and pulmonary blood volume (PBV) are affected during intra-abdominal CO2-insufflation, which may be pronounced by positional changes of the patient.

METHODS

Sixteen anaesthetized patients were studied before, during and after CO2-pneumoperitoneum for laparoscopic cholecystectomy. A dye indicator technique was used to assess ITBV and PBV. In addition, gas exchange and haemodynamics were recorded.

RESULTS

In the supine position, induction of CO2-pneumoperitoneum had no effects on ITBV, PBV and cardiac output. Mean systemic arterial pressure increased from 10.9 +/- 1.5 kPa (82 +/- 11 mmHg) to 12.7 +/- 1.5 kPa (95 +/- 11 mmHg, P < 0.01). In the reverse Trendelenburg position ITBV decreased from 19.8 +/- 5.1 ml.kg-1 to 16.7 +/- 3.7 ml.kg-1 (P < 0.05) during CO2-insufflation, but increased to control values after 20 min. PBV decreased from 4.2 +/- 1.2 ml.kg-1 to 3.4 +/- 1.1 ml.kg (P < 0.05) and remained decreased during CO2-pneumoperitoneum. Calculated venous admixture was unchanged throughout the study. Deflation of CO2-pneumoperitoneum increased ITBV (22.4 +/- 5.2 ml.kg-1, P < 0.05) and cardiac output above control values.

CONCLUSIONS

In anaesthetized-paralyzed patients in the reverse Trendelenburg position intra-abdominal CO2-insufflation is associated with significant alterations of ITBV and PBV. The release of CO2-pneumoperitoneum is associated with a re-distribution of blood into the thorax.

Difference between arterial and end-tidal carbon dioxide pressures during laparoscopy in paediatric patients

PURPOSE

To assess the effect of pneumoperitoneum on P(a-ET)CO2 gradient in children.

METHODS

Sixty one ASA I and II children (10.7 +/- 3.0 yr, 38.4 +/- 14.2 kg, mean +/- SD), scheduled for visceral or urological laparoscopic procedures, were studied. They were anaesthetized, intubated, paralysed and their lungs ventilated with constant ventilator settings to obtain PETCO2 values between 4.3 and 4.8 kPa. Intra-abdominal pressure was maintained between 8 and 14 mmHg. The following measurements were performed at steady state, before the pneumoperitoneum (T1) and 15 min later (T2): heart rate, systolic and diastolic arterial pressure; peak airway and intra-abdominal pressure; PaCO2 corrected for the patient's temperature; PETCO2 drawn between the micropore filter and the ventilator tubes, corrected for BTPS conditions; P(a-ET)CO2. Values between -1.0 and +1.0 mmHg were considered nil; patient position (horizontal or head-down tilt): all patients were horizontal at T1.

RESULTS

Arterial pressure, heart rate and peak airway pressure increased at T2: PaCO2 and PETCO2 increased by 14%. The incidence of negative gradients increased from 54 to 67% although mean P(a-ET)CO2 remained clinically unchanged. No difference was found in P(a-ET)CO2 gradient, whatever the position and intra-abdominal pressure. The 95% confidence intervals for P(a-ET)CO2 were [-5.6; +3.2] at T1 and [-8.8; +4.8] at T2.

CONCLUSION

PETCO2 often overestimates PaCO2 during laparoscopy in children, by up to 8.8 mmHg. Arterial blood gas analysis should be performed during long procedures to avoid hyperventilation.