Effects of Trendelenburg and reverse Trendelenburg postures on lung and chest wall mechanics

Trendelenburg position for internal jugular vein catheterization: A systematic review and meta-analysis

To determine the effect of Trendelenburg position on the diameter or cross-section area of the internal jugular vein (IJV) a systematic review and metanalysis was performed. Studies that evaluated the cross-sectional area (CSA) and anteroposterior (AP) diameter of the right internal jugular vein (RIJV) with ultrasonography in supine and any degree of head-down tilt (Trendelenburg position) were analyzed. A total of 22 articles (613 study subjects) were included. A >5° Trendelenburg position statistically increases RIJV CSA and AP diameter. Further inclination from 10° does not statistically benefit IJV size. This position should be recommended for CVC placement, when patient conditions allow it, and US-guided cannulation is not available.

The Extraperitoneal Approach to Left-Sided Colorectal Resections: A Human Cadaveric Study

INTRODUCTION

Technical challenges during laparoscopic and robotic anterior resection include identification of key retroperitoneal structures and obtaining clear views of the inferior mesenteric artery (IMA) pedicle and total mesorectal excision (TME) plane. Steep head-down position improves surgical exposure but is associated with cerebral oedema, high intrapulmonary pressures, and rare neurological complications. In this article we describe the key steps of an anterior resection performed via the extra-peritoneal (XP) space in the supine position.

METHODS

The technique of same-side lateral-to-medial XP dissection has been developed and refined in serial cadaveric workshops. A standard periumbilical port is inserted for initial laparoscopic exploration. Dissection is then performed in the left XP space via a 5 cm skin incision (later used as the extraction site) to allow for insertion of four (latterly three) working ports. The colon is mobilized along its lateral attachments, reflecting retroperitoneal structures down and away. The IMA pedicle is taken proximally, next to the duodenum. If required, TME dissection can be continued in the same plane. A short intraperitoneal phase is then required to complete the procedure.

RESULTS

Eight cadavers were studied (seven males; median 78 y). Four operations were performed laparoscopically and four robotically. Excellent views of the key retroperitoneal structures were achieved early in the procedure. Anatomical identification was performed sequentially for left-sided structures-psoas tendon, gonadal vessel, ureter, common iliac artery, IMA, and duodenum before ligation of the IMA pedicle. High ligation of IMA on the aorta and splenic flexure mobilization were performed in all eight procedures.

CONCLUSIONS

This novel study shows it is feasible to perform the key steps of an anterior resection using the XP space in the supine position. This will reduce the need for steep head-down positioning which may have meaningful clinical benefits. Prospective clinical studies are required to validate the technique within a patient population.

Author\'s Response to Trendelenburg Ventilation in Acute Respiratory Distress Syndrome: Should We Do More than Proning?

How to cite this article: Kodamanchili S. Author's Response to Trendelenburg Ventilation in Acute Respiratory Distress Syndrome: Should We Do More than Proning? Indian J Crit Care Med 2022;26(8):978–979.

Trendelenburg in Acute Respiratory Distress Syndrome: Should We Do More than Proning?

How to cite this article: Datta PK, Kundu R. Trendelenburg in Acute Respiratory Distress Syndrome: Should We Do More than Proning? Indian J Crit Care Med 2022;26(8):976–977.

Effects of sevoflurane and propofol on the optic nerve sheath diameter in patients undergoing laparoscopic gynecological surgery: a randomized controlled clinical studies

Background

The results of studies on changes in intracranial pressure in patients undergoing laparoscopic surgery are inconsistent. Meanwhile, previous neurosurgery studies have suggested that propofol and sevoflurane have inconsistent effects on cerebral blood flow and cerebrovascular self-regulation. The purpose of this study is to compare changes in the optic nerve sheath diameter in patients undergoing laparoscopic gynecological surgery under anesthetic maintenance with propofol versus sevoflurane.

Methods

This study included 110 patients undergoing laparoscopic gynecological surgery with an estimated operative time of more than 2 h under general anesthesia. The study was a randomized controlled study. The optic nerve sheath diameter (ONSD) at various time points was measured by ultrasound, including when the patients entered the operating room (Tawake), after successful anesthesia induction and endotracheal intubation (Tinduction), when the body position was adjusted to the Trendelenburg position and the CO₂ pneumoperitoneum pressure reached 14 mmHg, which was recorded as T₀. Then, measurements were conducted every 15 min for the first 1 h and then once every hour until the end of the surgery (T₁₅, T₃₀, T₄₅, T_1h, T_2h …), after the end of surgery and the tracheal tube was removed (T_end), and before the patients were transferred to the ward (T_pacu).

Results

A significant difference in optic nerve sheath diameter was found between two groups at T₁₅, T₃₀, T₄₅ (4.64 ± 0.48 mm and 4.50 ± 0.29 mm, respectively, p = 0.031;4.77 ± 0.45 mm and 4.62 ± 0.28 mm, respectively, p = 0.036;4.84 ± 0.46 mm and 4.65 ± 0.30 mm, respectively, p = 0.012), while there was no significant difference at T_awake and other time points.

Conclusion

During laparoscopic gynecological surgery lasting more than 2 h, the optic nerve sheath diameter was slightly larger in the propofol group than that in the sevoflurane group in the first 45 min. No significant difference was observed between the two groups 1 h after surgery.

Trial registration

clinicaltrials.gov, NCT03498235. Retrospectively registered 1 March 2018.

The manuscript adheres to CONSORT guidelines.

The effects of hospital bed features on physical stresses on caregivers when repositioning patients in bed

Repositioning patients in bed is the most common patient handling activity and is associated with musculoskeletal disorders in caregivers. Hospital bed features may mitigate the risk of injury. The current study investigated the effect of bed features on the physical stress on caregivers. Ten nurses were recruited to perform three repositioning activities. Hand forces were recorded, and spine loading was estimated using a dynamic biomechanical model. Results demonstrated that except for the peak L5/S1 compressive load in the turning task, the use of assistive features significantly reduced the physical stresses for all repositioning activities. However, recommended thresholds for injury were still exceeded in many conditions. Compared with spinal load, hand force was much higher relative to the injury thresholds, suggesting a greater risk of shoulder and upper extremity injuries than low back injury. Mechanical lift equipment remains the safest and most robust way to reposition a patient.

Effect of positive end-expiratory pressure and positioning on jugular vein expansion in emergency department patients

OBJECTIVE

Guidelines recommend Trendelenburg position for central venous cannulation. Critically ill patients in the emergency department often do not tolerate this positioning or have contraindications. Thirty-degree dorsal elevated position with positive end-expiratory pressure by noninvasive ventilation could pose an alternative. This is the first trial to investigate the feasibility of alternative for central venous cannulation in critically ill emergency department patients.

METHODS

Ninety-one critically ill patients in the emergency department of Jena University Hospital were examined between August 2014 and May 2015. The cross-sectional area of the right internal jugular vein was measured in 3 different positions: 30° elevation, supine, and Trendelenburg position. Measurements were repeated with a continuous application of noninvasive ventilation.

RESULTS

Cross-sectional area of the right internal jugular vein in Trendelenburg position was largest (0.99 ± 0.66 cm) compared to supine (0.57 ± 0.58 cm) and 30° elevated position (0.25 ± 0.41 cm). In 30° elevated positioning, application of positive end-expiratory pressure significantly enlarged cross-sectional area (0.62 ± 0.70 cm). Noninvasive ventilation was a well-tolerated procedure (98%). In 30° elevated positioning with positive end-expiratory pressure a safe puncture (cross-sectional area ≥ 0.4 cm) could be expected in 68.1% of cases.

CONCLUSION

Thirty-degree elevated positioning with positive end-expiratory pressure via noninvasive ventilation could be a safe and well-tolerated alternative for central venous cannulation, especially for critically ill patients in emergency department unable to remain in Trendelenburg position. This proof-of-concept trial enables further studies with actual central venous cannulation.

Trendelenburg position in the ED: many critically ill patients in the emergency department do not tolerate the Trendelenburg position

OBJECTIVES

Critically ill patients in emergency departments (ED) frequently require catheterization of the internal jugular vein. For jugular insertion, the Trendelenburg position (TP) is recommended. However, many patients in the ED do not tolerate lying in the supine or even the head-down position, or TP is contraindicated for other reasons. The aim of our trial was to investigate to which extent TP is either not tolerated or contraindicated in the target population of patients admitted to the ED.

PATIENTS AND METHODS

This was a clinical observational trial, carried out in an ED of a Tertiary Healthcare Hospital, including critically ill patients. From October 2015 to January 2016, we enrolled 117 nonintubated patients over 18 years admitted to the ED of Jena University Hospital, a Tertiary Healthcare Facility. Patients were positioned in TP (15° head-down) for a maximum of 10 min. If the position had to be abandoned for any reason, time to abandonment and reason for ending the position were recorded. 38.5% of all enrolled patients could not be positioned in TP because of contraindications (17.9%) or intolerance of the positioning (20.5%).

RESULTS AND CONCLUSION

For central venous catheterization, TP remains the gold standard. Our trial shows the limitations of this positioning for critically ill patients. Almost 40% of the patients could not be tilted 15° head-down. Therefore, guideline recommendations should be reconsidered and alternatives should be sought.

The Effects of Positioning on the Volume/Location of the Internal Jugular Vein Using 2-Dimensional Tracked Ultrasound

OBJECTIVE

To investigate the effects of different positioning on the volume/location of the internal jugular vein (IJV) using 2-dimensional (2D) tracked ultrasound.

DESIGN

This was a prospective, observational study.

SETTING

Local research institute.

PARTICIPANTS

Healthy volunteers.

INTERVENTIONS

Twenty healthy volunteers were scanned in the following 6 positions: (1) supine with head neutral, rotated 15 and 30 degrees to the left and (2) 5-, 10-, and 15-degree Trendelenburg position with head neutral. In each position the volunteer's neck was scanned using a 2D ultrasound probe tracked with a magnetic tracker. These spatially tracked 2D images were collected and reconstructed into a 3D volume of the IJV and carotid artery. This 3D ultrasound volume then was segmented to obtain a 3D surface on which measurements and calculations were performed.

MEASUREMENTS AND MAIN RESULTS

The measurements included average cross-section area (CSA), CSA along the length of IJV, and average overlap rate. CSA (mm²) in the supine and 5-, 10-, and 15-degree Trendelenburg positions were as follows: 86.7 ± 44.8, 104.3 ± 54.5, 119.1 ± 58.6, and 133.7 ± 53.3 (p < 0.0001). CSA enlarged with the increase of Trendelenburg degree. Neither Trendelenburg position nor head rotation showed a correlation with overlap rate.

CONCLUSIONS

Trendelenburg position significantly increased the CSA of the IJV, thus facilitating IJV cannulation. This new 3D reconstruction method permits the creation of a 3D volume through a tracked 2D ultrasound scanning system with image acquisition and integration and may prove useful in providing the user with a "road map" of the vascular anatomy of a patient's neck or other anatomic structures.

Propofol attenuates the increase of sonographic optic nerve sheath diameter during robot-assisted laparoscopic prostatectomy: a randomized clinical trial

Background

Robot-assisted laparoscopic prostatectomy (RALP) requires pneumoperitoneum and the Trendelenburg position to optimize surgical exposure, which can increase intracranial pressure (ICP). Anesthetic agents also influence ICP. We compared the effects of propofol and sevoflurane on sonographic optic nerve sheath diameter (ONSD) as a surrogate for ICP in prostate cancer patients who underwent RALP.

Methods

Thirty-six patients were randomly allocated to groups receiving propofol (propofol group, n = 18) or sevoflurane (sevoflurane group, n = 18) anesthesia. The ONSD was measured 10 min after induction of anesthesia in the supine position (T1); 5 min (T2), 30 min (T3), and 60 min (T4) after establishing pneumoperitoneum and the Trendelenburg position; and at the end of surgery after desufflation in the supine position (T5). Respiratory and hemodynamic variables were also evaluated.

Results

The ONSD was significantly different between the propofol group and the sevoflurane group at T4 (5.27 ± 0.35 mm vs. 5.57 ± 0.28 mm, P = 0.007), but not at other time points. The ONSDs at T2, T3, T4, and T5 were significantly greater than at T1 in both groups (all P < 0.001). Arterial carbon dioxide partial pressure, arterial oxygen partial pressure, peak airway pressure, plateau airway pressure, systolic blood pressure, pulse pressure variation, body temperature and regional cerebral oxygen saturation, except heart rate, were not significantly different between the two groups.

Conclusions

The ONSD was significantly lower during propofol anesthesia than during sevoflurane anesthesia 60 min after pneumoperitoneum and the Trendelenburg position, suggesting that propofol anesthesia may help minimize ICP changes in robotic prostatectomy patients.

Trial registration

Clinicaltrials.gov identifier: NCT03271502. Registered August 31, 2017.

Comparison of Arterial Oxygenation Following Head-Down and Head-Up Laparoscopic Surgery

BACKGROUND

Regarding the role of gas entry in abdomen and cardiorespiratory effects, the ability of anesthesiologists would be challenged in laparoscopic surgeries. Considering few studies in this area and the relevance of the subject, this study was performed to compare the arterial oxygen alterations before operation in comparison with after surgery between laparoscopic cholecystectomy and ovarian cystectomy.

METHODS

In this prospective cohort, 70 consecutive women aged from 20 to 60 years who were candidate for laparoscopic cholecystectomy (n = 35) and ovarian cystectomy (n = 35) with reverse (20 degrees) and direct (30 degrees) Trendelenburg positions, respectively, with ASA class I or II were enrolled. After intubation and before operation, for the first time, the arterial blood gas from radial artery in supine position was obtained for laboratory assessment. Then, the second blood sample was collected from radial artery in supine position and sent to the lab to be assessed with the same device after 30 minutes from surgery termination. The measured variables from arterial blood gas were arterial partial pressure of oxygen (PaO2) and Oxygen saturation (SpO2) alterations.

RESULTS

Total PaO2 was higher in the first measurement. The higher values of PaO2 in cholecystectomy (upward) than in ovarian cystectomy (downward) were not significant in univariate (P = 0.060) and multivariate analysis (P = 0.654). Furthermore, higher values of SpO2 in cholecystectomy (upward) than in ovarian cystectomy (downward) were not significant in univariate (P = 0.412) and multivariate analysis (P = 0.984).

CONCLUSIONS

In general, based on the results of this study, the values of PaO2 in cholecystectomy (upward) were not significantly higher than the values in cystectomy (downward) in laparoscopic surgeries when measured 30 minutes after surgery.

Comparison of the Trendelenburg position versus upper-limb tourniquet on internal jugular vein diameter

BACKGROUND

Central venous cannulation is a necessary invasive procedure for fluid management, haemodynamic monitoring and vasoactive drug therapy. The right internal jugular vein (RIJV) is the preferred site. Enlargement of the jugular vein area facilitates catheterization and reduces complication rates. Common methods to enlarge the RIJV cross-sectional area are the Trendelenburg position and the Valsalva maneuver.

OBJECTIVE

Compare the Trendelenburg position with upper-extremity venous return blockage using the tourniquet technique.

DESIGN

Prospective clinical study.

SETTING

University hospital.

SUBJECTS AND METHODS

Healthy adult volunteers (American Society of Anesthesiologists class I) aged 18-45 years were included in the study. The first measurement was made when the volunteers were in the supine position. The RIJV diameter and cross-sectional area were measured from the apex of the triangle formed by the clavicle and the two ends of the sternocleidomastoid muscle, which is used for the conventional approach. The second measurement was performed in a 20° Trendelenburg position. After the drainage of the veins using an Esbach bandage both arms were cuffed. The third measurement was made when tourniquets were inflated.

MAIN OUTCOME MEASURE(S)

Hemodynamic measurements and RIJV dimensions.

RESULTS

In 65 volunteers the diameter and cross-sectional area of the RIJV were significantly widened in both Trendelenburg and tourniquet measurements compared with the supine position (P < .001 for both measures). Measurements using the upper extremity tourniquet were significantly larger than Trendelenburg measurements (P=.002 and < .001 for cross-sectional area and diameter, respectively).

CONCLUSION

Channelling of the upper-extremity venous return to the jugular vein was significantly superior when compared with the Trendelenburg position and the supine position.

LIMITATIONS

No catheterization and study limited to healthy volunteers.

Effect of Positive End-Expiratory Pressure on the Sonographic Optic Nerve Sheath Diameter as a Surrogate for Intracranial Pressure during Robot-Assisted Laparoscopic Prostatectomy: A Randomized Controlled Trial

Background

Positive end-expiratory pressure (PEEP) can increase intracranial pressure. Pneumoperitoneum and the Trendelenburg position are associated with an increased intracranial pressure. We investigated whether PEEP ventilation could additionally influence the sonographic optic nerve sheath diameter as a surrogate for intracranial pressure during pneumoperitoneum combined with the Trendelenburg position in patients undergoing robot-assisted laparoscopic prostatectomy.

Methods

After anesthetic induction, 38 patients were randomly allocated to a low tidal volume ventilation (8 ml/kg) without PEEP group (zero end-expiratory pressure [ZEEP] group, n = 19) or low tidal volume ventilation with 8 cmH₂O PEEP group (PEEP group, n = 19). The sonographic optic nerve sheath diameter was measured prior to skin incision, 5 min and 30 min after pneumoperitoneum and the Trendelenburg position, and at the end of surgery. The study endpoint was the difference in the sonographic optic nerve sheath diameter 5 min after pneumoperitoneum and the Trendelenburg position between the ZEEP and PEEP groups.

Results

Optic nerve sheath diameters 5 min after pneumoperitoneum and the Trendelenburg position did not significantly differ between the groups [least square mean (95% confidence interval); 4.8 (4.6–4.9) mm vs 4.8 (4.7–5.0) mm, P = 0.618]. Optic nerve sheath diameters 30 min after pneumoperitoneum and the Trendelenburg position also did not differ between the groups [least square mean (95% confidence interval); 4.5 (4.3–4.6) mm vs 4.5 (4.4–4.6) mm, P = 0.733].

Conclusions

An 8 cmH₂O PEEP application under low tidal volume ventilation does not induce an increase in the optic nerve sheath diameter during pneumoperitoneum combined with the steep Trendelenburg position, suggesting that there might be no detrimental effects of PEEP on the intracranial pressure during robot-assisted laparoscopic prostatectomy.

Trial Registration

ClinicalTrial.gov NCT02516566

Respiratory dynamics and dead space to tidal volume ratio of volume-controlled versus pressure-controlled ventilation during prolonged gynecological laparoscopic surgery

BACKGROUND

Laparoscopic operations have become longer and more complex and applied to a broader patient population in the last decades. Prolonged gynecological laparoscopic surgeries require prolonged pneumoperitoneum and Trendelenburg position, which can influence respiratory dynamics and other measurements of pulmonary function. We investigated the differences between volume-controlled ventilation (VCV) and pressure-controlled ventilation (PCV) and tried to determine the more efficient ventilation mode during prolonged pneumoperitoneum in gynecological laparoscopy.

METHODS

Twenty-six patients scheduled for laparoscopic radical hysterectomy combined with or without laparoscopic pelvic lymphadenectomy were randomly allocated to be ventilated by either VCV or PCV. Standard anesthesic management and laparoscopic procedures were performed. Measurements of respiratory and hemodynamic dynamics were obtained after induction of anesthesia, at 10, 30, 60, and 120 min after establishing pneumoperitoneum, and at 10 min after return to supine lithotomy position and removal of carbon dioxide. The logistic regression model was applied to predict the corresponding critical value of duration of pneumoperitoneum when the Ppeak was higher than 40 cmH₂O.

RESULTS

Prolonged pneumoperitoneum and Trendelenburg position produced significant and clinically relevant changes in dynamic compliance and respiratory mechanics in anesthetized patients under PCV and VCV ventilation. Patients under PCV ventilation had a similar increase of dead space/tidal volume ratio, but had a lower Ppeak increase compared with those under VCV ventilation. The critical value of duration of pneumoperitoneum was predicted to be 355 min under VCV ventilation, corresponding to the risk of Ppeak higher than 40 cmH₂O.

CONCLUSIONS

Both VCV and PCV can be safely applied to prolonged gynecological laparoscopic surgery. However, PCV may become the better choice of ventilation after ruling out of other reasons for Ppeak increasing.

Sonographic optic nerve sheath diameter as a surrogate measure for intracranial pressure in anesthetized patients in the Trendelenburg position

BACKGROUND

It remains to be elucidated whether the Trendelenburg position increases intracranial pressure (ICP). ICP can be evaluated by measuring the sonographic optic nerve sheath diameter (ONSD). We investigated the effect of the isolated Trendelenburg position on ONSD in patients undergoing robot-assisted laparoscopic radical prostatectomy. Additionally, we evaluated the effect of the Trendelenburg position combined with pneumoperitoneum on ONSD.

METHODS

Twenty-one patients scheduled for robot-assisted laparoscopic radical prostatectomy were enrolled. Sonographic ONSDs and hemodynamic parameters were measured at specific time points: in the supine position after induction of anesthesia, 3 min after the steep Trendelenburg position (35° incline), 3 min after the steep Trendelenburg position combined with pneumoperitoneum, and in the supine position after desufflation of the pneumoperitoneum.

RESULTS

The ONSD 3 min after the steep Trendelenburg position was significantly higher than that of the supine position after induction of anesthesia (5.1 ± 0.3 mm vs. 4.5 ± 0.4 mm). In addition, the ONSD 3 min after the steep Trendelenburg position combined with pneumoperitoneum was higher than that of the supine position after induction of anesthesia (4.9 ± 0.4 mm vs. 4.5 ± 0.4 mm). The ONSD in the supine position after desufflation of the pneumoperitoneum was similar to that in the supine position after induction of anesthesia.

CONCLUSIONS

Use of the isolated steep Trendelenburg position, for even a short duration, increased the sonographic ONSD, providing a better understanding of the effect of only a transient steep Trendelenburg position on ONSD as a surrogate measure for ICP.

Trendelenburg position does not increase cross-sectional area of the internal jugular vein predictably

BACKGROUND

The Trendelenburg position is used to distend the central veins, improving both the success and safety of vascular cannulation. The purpose of this study was to measure the cross-sectional area (CSA) of the internal jugular vein (IJV) in three different positions using surface ultrasonography.

METHODS

Fifty-one subjects were enrolled. A Sono Site Titan 180 or M-Turbo portable ultrasound machine with a 10.5-mHz broadband linear surface probe was used. We measured the CSA of the IJV (at end-expiration at the level of the cricoid cartilage) in three positions: 15° reverse Trendelenburg, supine, and 15° Trendelenburg.

RESULTS

The mean CSA at 15° reverse Trendelenburg was 0.83 cm2 (SD, 0.86), in the supine position it was 1.25 cm2 (SD, 0.98), and at -15° Trendelenburg it was 1.47 cm2 (SD, 1.03). Moving from reverse Trendelenburg to supine, the CSA increased by 50%. In contrast, lowering the head to a Trendelenburg position increased the mean CSA by only 17%. Surprisingly, Trendelenburg positioning reduced the CSA in nine of the 51 subjects.

CONCLUSIONS

Trendelenburg positioning augments the CSA only modestly, on average, compared with the supine position, and in some patients it reduces the CSA.

TRIAL REGISTRATION

ClinicalTrials.gov; No.: NCT01099254; URL: www.clinicaltrials.gov.

Effects of the pneumoperitoneum and Trendelenburg position on respiratory mechanics in the rats by the end-inflation occlusion method

PURPOSE:

To describe the consequences of the cranial displacement of the diaphgram occurring during pneumoperitoneum (Pnp) and/or Trendelenburg (Tnd) position on respiratory mechanics. Possible addictive effects and the changes of the viscoelastic respiratory system resistance were studied, which were not extensively described before.

METHODS:

The end-inflation occlusion method was applied on eight rats. It allows us to determine mechanical parameters such as respiratory system static elastance, the ohmic resistance due to frictional forces in the airways, and the additional viscoelastic impedance due to tissues deformation. Measurements during mechanical ventilation were taken in controls (supine position), after 20–25° head-down tilting (Tnd), after abdominal air insufflation up to 12 mmHg abdominal pressure in the supine position (Pnp), and combining Tnd + Pnp. Tnd and Pnp modalities were similar to those commonly applied during surgical procedures in humans.

RESULTS:

We confirmed the previously described detrimental effects on respiratory mechanics due to the diaphgram displacement during both Pnp and Tnd. The increment in the total resistive pressure dissipation was found to depend primarily on the effects on the viscoelastic characteristics of the respiratory system. Data suggesting greater effects of Pnp compared to those of Tnd were obtained.

CONCLUSION:

The cranial displacement of the diaphgram occurring as a consequence of Pnp and/or Tnd, for example during laparoscopic surgical procedures, causes an increment of respiratory system elastance and viscoelastic resistance. The analysis of addictive effects show that these are more likely to occur when Pnp + Tnd are compared to isolated Tnd rather than to isolated Pnp.

Laparoscopic approach to acute abdomen from the Consensus Development Conference of the Società Italiana di Chirurgia Endoscopica e nuove tecnologie (SICE), Associazione Chirurghi Ospedalieri Italiani (ACOI), Società Italiana di Chirurgia (SIC), Società Italiana di Chirurgia d'Urgenza e del Trauma (SICUT), Società Italiana di Chirurgia nell'Ospedalità Privata (SICOP), and the European Association for Endoscopic Surgery (EAES)

BACKGROUND

In January 2010, the SICE (Italian Society of Endoscopic Surgery), under the auspices of the EAES, decided to revisit the clinical recommendations for the role of laparoscopy in abdominal emergencies in adults, with the primary intent being to update the 2006 EAES indications and supplement the existing guidelines on specific diseases.

METHODS

Other Italian surgical societies were invited into the Consensus to form a panel of 12 expert surgeons. In order to get a multidisciplinary panel, other stakeholders involved in abdominal emergencies were invited along with a patient's association. In November 2010, the panel met in Rome to discuss each chapter according to the Delphi method, producing key statements with a grade of recommendations followed by commentary to explain the rationale and the level of evidence behind the statements. Thereafter, the statements were presented to the Annual Congress of the EAES in June 2011.

RESULTS

A thorough literature review was necessary to assess whether the recommendations issued in 2006 are still current. In many cases new studies allowed us to better clarify some issues (such as for diverticulitis, small bowel obstruction, pancreatitis, hernias, trauma), to confirm the key role of laparoscopy (such as for cholecystitis, gynecological disorders, nonspecific abdominal pain, appendicitis), but occasionally previous strong recommendations have to be challenged after review of recent research (such as for perforated peptic ulcer).

CONCLUSIONS

Every surgeon has to develop his or her own approach, taking into account the clinical situation, her/his proficiency (and the experience of the team) with the various techniques, and the specific organizational setting in which she/he is working. This guideline has been developed bearing in mind that every surgeon could use the data reported to support her/his judgment.

A comparison of pressure-controlled and volume-controlled ventilation for laparoscopic cholecystectomy

The potential advantages of pressure-controlled over volume-controlled ventilation during laparoscopic surgery have yet to be proven. We randomly assigned 42 patients with BMI <30 kg.m(-2) scheduled for laparoscopic cholecystectomy to receive either pressure- or volume-controlled ventilation. Compared with volume-controlled ventilation, pressure-controlled ventilation resulted in a significant decrease in mean (SD) peak airway pressure at 10 min (20.4 (2.7) vs 24.0 (4.7)cmH₂O, p=0.004) and 30 min (20.7 (3.0) vs 23.9 (4.9)cmH₂O, p=0.015) and an increase in mean airway pressure at 10 min (10.5 (0.9) vs 9.6 (1.1)cmH₂O, p=0.007) and 30 min (10.5 (1.1) vs 9.6 (1.2)cmH₂O, p=0.016) after the start of surgery. Gas exchange and haemodynamic stability were similar. We conclude that pressure-controlled ventilation is a safe alternative and offers some advantages to volume-controlled ventilation during laparoscopic cholecystectomy in non-obese patients.

The effect of pneumoperitoneum and Trendelenburg position on respiratory mechanics during pelviscopic surgery

Background

Conventional pelviscopic surgery requires pneumoperitoneum with CO₂ gas insufflation and lithotomy-Trendelenburg position. Pneumoperitoneum and Trendelenburg position may influence intraoperative respiratory mechanics in anesthetic management. This study was conducted to investigate the influence of pneumoperitoneum and Trendelenburg position on respiratory compliance and ventilation pressure.

Methods

Twenty-five patients scheduled for elective gynecologic laparoscopy were evaluated. The patients had no preexisting lung or heart disease or pathologic lung function. Conventional general anesthesia with thiopental sodium, lidocaine, rocuronium, and sevoflurane was administered. The peak inspiratory pressure, plateau pressure, and end-tidal CO₂ were measured before and after creation of pneumoperitoneum with an intraabdominal pressure of 12 mmHg, then after 10 minutes and 30 minutes in the 20° Trendelenburg position, and after deflation of pneumoperitoneum. The dynamic lung compliance was then calculated.

Results

Following creation of pneumoperitoneum, there was a significant increase in peak inspiratory pressure (6 cmH₂O), plateau pressure (7 cmH₂O), and end-tidal CO₂ (5 mmHg), while dynamic lung compliance decreased by 12 ml/cmH₂O. Overall, the Trendelenburg position induced no significant hemodynamic or pulmonary changes.

Conclusions

The effects of pneumoperitoneum significantly reduced dynamic lung compliance and increased peak inspiratory and plateau pressures. The Tredelenburg position did not change these parameters.

Management of mechanical ventilation during laparoscopic surgery

Laparoscopy is widely used in the surgical treatment of a number of diseases. Its advantages are generally believed to lie on its minimal invasiveness, better cosmetic outcome and shorter length of hospital stay based on surgical expertise and state-of-the-art equipment. Thousands of laparoscopic surgical procedures performed safely prove that mechanical ventilation during anaesthesia for laparoscopy is well tolerated by a vast majority of patients. However, the effects of pneumoperitoneum are particularly relevant to patients with underlying lung disease as well as to the increasing number of patients with higher-than-normal body mass index. Moreover, many surgical procedures are significantly longer in duration when performed with laparoscopic techniques. Taken together, these factors impose special care for the management of mechanical ventilation during laparoscopic surgery. The purpose of the review is to summarise the consequences of pneumoperitoneum on the standard monitoring of mechanical ventilation during anaesthesia and to discuss the rationale of using a protective ventilation strategy during laparoscopic surgery. The consequences of chest wall derangement occurring during pneumoperitoneum on airway pressure and central venous pressure, together with the role of end-tidal-CO2 monitoring are emphasised. Ventilatory and non-ventilatory strategies to protect the lung are discussed.

[Special features of laparoscopic operations from an anesthesiologic viewpoint: a review]

The value of laparoscopic procedures has increased over the last decade. Many patients undergoing laparoscopic surgery also have coexisting diseases. The hemodynamic effects of intraperitoneal carbon dioxide insufflation depend on the extent of intraperitoneal pressure, severity of preexisting cardiopulmonary diseases, volume state of the patient and alterations of acid-base balance due to a capnoperitoneum. In addition to endocrinologic reactions, patient positioning also affects hemodynamic parameters. In high risk patients extended cardiopulmonary monitoring with an arterial line and repeated blood gas analysis is recommended intraoperatively, in addition to assessment of end-expiratory CO(2). In this patient group the intra-abdominal pressure should be maintained in the range of 5-7 mmHg.

Posture-dependent human 3He lung imaging in an open-access MRI system: initial results

RATIONALE AND OBJECTIVES

The human lung and its functions are extremely sensitive to orientation and posture, and debate continues as to the role of gravity and the surrounding anatomy in determining lung function and heterogeneity of perfusion and ventilation. However, study of these effects is difficult. The conventional high-field magnets used for most hyperpolarized (3)He magnetic resonance imaging (MRI) of the human lung, and most other common radiologic imaging modalities including positron emission tomography and computed tomography, restrict subjects to lying horizontally, minimizing most gravitational effects.

MATERIALS AND METHODS

In this article, we review the motivation for posture-dependent studies of human lung function and present initial imaging results of human lungs in the supine and vertical body orientations using inhaled hyperpolarized (3)He gas and an open-access MRI instrument. The open geometry of this MRI system features a "walk-in" capability that permits subjects to be imaged in vertical and horizontal positions and potentially allows for complete rotation of the orientation of the imaging subject in a two-dimensional plane.

RESULTS

Initial results include two-dimensional lung images acquired with approximately 4 x 8 mm in-plane resolution and three-dimensional images with approximately 2-cm slice thickness.

CONCLUSIONS

Effects of posture variation are observed, including posture-related effects of the diaphragm and distension of the lungs while vertical.

A clinician's guide to predicting fluid responsiveness in critical illness: applied physiology and research methodology

Intravenous fluid administration is often used in critical care with the goal of improving haemodynamics and consequently tissue perfusion and oxygen delivery. While inotropic and vasoactive drugs are often necessary to correct haemodynamic instability, resuscitation usually begins with fluid therapy. As fluid challenge can result in clinical deterioration, the ability to predict haemodynamic response is desirable. In this way it might be possible to avoid unnecessary volume replacement in critically ill patients. Cardiac preload is a concept that accounts for the relationship between ventricular filling and stroke volume. It has been challenging to apply this concept to clinical practice. For this reason, the study of fluid responsiveness is of increasing research and clinical interest. The clinical application of predicting fluid responsiveness requires an understanding of relevant physiological principles. Furthermore, an improved understanding of these principles should assist the clinician in appraising published data, which has been characterised by significant methodological differences. This review aims to assist the clinician by detailing the physiological principles that underlie the prediction of fluid responsiveness in the critically ill. In addition, the potential importance of methodological differences in the cutrent literature will be considered.

Laparoscopic Extraperitoneal Radical Prostatectomy in Complex Surgical Cases

PURPOSE

Patients with a high body mass index, previous pelvic surgery or large prostate size are not considered ideal candidates for radical prostatectomy. We assessed the impact of body mass index, previous pelvic surgery and prostate weight on perioperative and pathological outcomes in patients treated exclusively with laparoscopic extraperitoneal radical prostatectomy.

MATERIALS AND METHODS

From January 2004 to May 2005, 300 patients underwent laparoscopic extraperitoneal radical prostatectomy. Patients were divided into groups, including body mass index groups 1 (25 kg/m(2) or less), 2 (25.1 to 30), 3 (30.1 to 36) and 4 (greater than 36); prostate weight groups 1 (20 gm or less), 2 (20.1 to 40), 3 (40.1 to 60) and 4 (more than 60); and prior surgery groups 1 (no previous pelvic or prostatic surgery) and 2 (previous pelvic or prostatic surgery).

RESULTS

Logistic regression demonstrated that body mass index, large prostate size and previous pelvic surgery did not affect margin status. The Kruskal-Wallis test was performed to analyze if body mass index, large prostate size and previous pelvic surgery had an effect on perioperative variables. Only prostate weight correlated with a delay in Foley catheter removal (3 days, p=0.0005). The Wilcoxon rank sum test showed that patients with a higher body mass index had a slightly prolonged hospital stay (16 hours, p=0.02). Patients with a prostate of more than 40 gm had slightly increased blood loss (56 cc, p=0.03), which did not affect the transfusion rate.

CONCLUSIONS

Laparoscopic extraperitoneal radical prostatectomy can be performed in complex surgical cases without increased perioperative morbidity. Obese patients and those with a large prostate who prefer surgery as a treatment option for localized prostate cancer may benefit from the advantages that laparoscopic extraperitoneal radical prostatectomy offers.

Impact of Overweight and Pneumoperitoneum on Hemodynamics and Oxygenation during Prolonged Laparoscopic Surgery

BACKGROUND

Anesthesia adversely affects respiratory function and hemodynamics in obese patients. Although many studies have been performed in morbidly obese patients, data are limited concerning overweight patients [BMI 25-29.9 kg m(-2)]. The aim of this study was to evaluate the effects of prolonged pneumoperitoneum in Trendelenburg position on hemodynamics and gas exchange in normal and overweight patients.

METHODS

We studied 15 overweight and 15 non-obese [BMI 18.5-24.9 kg m(-2)] patients who underwent totally endoscopic robot-assisted radical prostatectomy under general anesthesia with an inspired oxygen fraction of 0.5. A standardized anesthetic regimen was used, and patients were examined at standard times: after induction of anesthesia and Trendelenburg posture, every 30 minutes after establishing pneumoperitoneum, and after the release of the pneumoperitoneum with the patient still in Trendelenburg position.

RESULTS

After induction of anesthesia and Trendelenburg positioning arterial oxygen pressure [P(a)O2] and alveolar-arterial difference in oxygen tension [A(a)DO2] differed significantly between both groups with lower P(a)O2 [235 +/- 27 versus 164 +/- 51 mmHg] and higher A(a)DO2 [149 +/- 48 versus 76 +/- 28 mmHg] values in overweight patients. During pneumoperitoneum, P(a)O2 transient increased above baseline values in overweight patients, whereas A(a)DO2 decreased. Hemodynamic parameters [HR, MAP, and CVP] did not differ significantly between groups.

CONCLUSIONS

Arterial oxygenation and A(a)DO2 are significantly impaired in overweight patients under general anesthesia in Trendelenburg posture. In overweight patients pneumoperitoneum transient reduced the impairment of arterial oxygenation and lead to a decrease in A(a)DO2. Hemodynamic parameters were not affected by body weight.

The impact of morbid obesity, pneumoperitoneum, and posture on respiratory system mechanics and oxygenation during laparoscopy

We studied the effect of morbid obesity, 20 mm Hg pneumoperitoneum, and body posture (30 degrees head down and 30 degrees head up) on respiratory system mechanics, oxygenation, and ventilation during laparoscopy. We hypothesized that insufflation of the abdomen with CO(2) during laparoscopy would produce more impairment of respiratory system mechanics and gas exchange in the morbidly obese than in patients of normal weight. The static respiratory system compliance and inspiratory resistance were computed by using a Servo Screen pulmonary monitor. A continuous blood gas monitor was used to monitor real-time PaCO(2) and PaO(2), and the ETCO(2) was recorded by mass spectrometry. Static compliance was 30% lower and inspiratory resistance 68% higher in morbidly obese supine anesthetized patients compared with normal-weight patients. Whereas body posture (head down and head up) did not induce additional large alterations in respiratory mechanics, pneumoperitoneum caused a significant decrease in static respiratory system compliance and an increase in inspiratory resistance. These changes in the mechanics of breathing were not associated with changes in the alveolar-to-arterial oxygen tension difference, which was larger in morbidly obese patients. Before pneumoperitoneum, morbidly obese patients had a larger ventilatory requirement than the normal-weight patients to maintain normocapnia (6.3 +/- 1.4 L/min versus 5.4 +/- 1.9 L/min, respectively; P = 0.02). During pneumoperitoneum, morbidly obese, supine, anesthetized patients had less efficient ventilation: a 100-mL increase of tidal volume reduced PaCO(2) on average by 5.3 mm Hg in normal-weight patients and by 3.6 mm Hg in morbidly obese patients (P = 0.02). In conclusion, respiratory mechanics during laparoscopy are affected by obesity and pneumoperitoneum but vary little with body position. The PaO(2) was adversely affected only by increased body weight.

IMPLICATIONS

Morbid obesity significantly decreases respiratory system compliance and increases inspiratory resistance. Increased body weight, and not altered mechanics of breathing, was associated with worse PaO(2) during laparoscopy.

Respiratory system mechanics during laparoscopic cholecystectomy

The influence of laparoscopic cholecystectomy (LC) on the mechanical properties of the respiratory system (RS) was examined using multiple regression analysis (MRA). Measurements of airway pressure (PaO) and flow (V') were obtained from 32 patients at four distinct stages of the LC procedure: 1) Immediately before the application of pneumoperitoneum (PP) at supine position, 2) 5 min after the induction of PP at Trendelenburg position, 3) 5 min after the patients position at reverse Trendelenburg, and 4) 5 min after the end ofthe surgical procedure with the patient again in supine position. Evaluated parameters were the RS elastance (Ers), resistance (Rrs), impedance (Zrs), the angle theta indicating the balance between the elastic and resistive components of the impedance, as well as the end-expiratory elastic recoil pressure (EEP). Ers and Zrs increased considerably during PP and remained elevated immediately after abolishing PP Rrs, on the contrary, returned to pre-operative levels right after the operation. Change of body position from Trendelenburg (T) to reverseTrendelenburg (rT) mainly induced a significant change in theta, thus indicating an increased dominance of the elastic component of Zrs on changing fromT to rT. There was no evidence of increased End-Expiratory Pressure during PP

Pressure controlled versus volume controlled ventilation with laryngeal mask airway

STUDY OBJECTIVE

To quantify the impact on peak airway pressure of pressure-controlled and volume-controlled ventilation during Laryngeal Mask Airway (LMA) use.

DESIGN

Prospective, crossover clinical study.

SETTING

University-affiliated hospital.

PATIENTS

32 ASA physical status I and II patients undergoing general anesthesia with the LMA.

INTERVENTIONS

Patients were ventilated for three minutes both with pressure-controlled and volume-controlled ventilation, provided that tidal volume (V(T) ) and inspiratory time (It) were constant.

MEASUREMENTS AND MAIN RESULTS

The monitored parameters were electrocardiography, arterial blood pressure, pulse oximetry, capnography, neuromuscular transmission, airway pressure and flow, and concentration of ventilated vapors and gases. The actually delivered V(T) was similar with both types of ventilation (volume-controlled = 0.67 +/- 0.13 lt, pressure-controlled = 0.67 +/- 0.14 lt; p = 0.688). Peak airway pressure was lower during pressure-controlled ventilation (14.6 +/- 3.5 cmH(2)O) than during volume-controlled ventilation (16 +/- 4 cmH(2)O) (p < 0.001). Furthermore, we noted that the higher the airway pressure with volume-controlled ventilation, the greater was the reduction in airway pressure during pressure-controlled ventilation.

CONCLUSIONS

Pressure-controlled rather than volume-controlled ventilation can improve the effectiveness of mechanical ventilation in patients with high airway pressure.

Effects of PEEP on respiratory mechanics are tidal volume and frequency dependent

How the effects of frequency, tidal volume (VT) and PEEP interact to determine the mechanical properties of the respiratory system is unclear. Airway flow and airway and esophageal pressures were measured in ten intubated, anesthetized/paralyzed patients during mechanical ventilation at 10-30 breaths/min and VT of 250-800 ml. From these measurements, Fourier transformation was used to calculate elastance (E) and resistance (R) of the total respiratory system (subscript rs), lungs (subscript L) and chest wall (subscript cw) at 5, 10 and 0 cm PEEP. As PEEP increased from 0-5 cmH2O, all elastances and resistances decreased (P < 0.05). Increasing PEEP to 10 cmH2O decreased EL, Rrs, and RL further (P < 0.05). The changes in Ers, EL, Rrs and RL caused by PEEP were less (P < 0.05) as VT increased, while changes in Rrs, RL and Ers were less (P < 0.05) as frequency increased. VT dependences in Ers and Rrs were enhanced (P < 0.05) at 0 cmH2O PEEP. The ratio of EL to chest wall elastance was not affected by PEEP (P > 0.05), but increased (P < 0.05) with increasing VT at 5 and 10 cmH2O PEEP. We conclude that it is critical to standardize ventilatory parameters when comparing groups of patients or testing clinical intervention efficacy and that the differential effects on the lungs and chest wall must be considered in optimizing the application of PEEP.