Low-pressure laparoscopy may ameliorate intracranial hypertension and renal hypoperfusion

Pneumoperitoneum and Acute Kidney Injury-An Integrative Clinical Concept Review

An increased intraabdominal pressure, particularly when occurring during periods of hemodynamic instability or fluid overload, is regarded as a major contributor to acute kidney injury (AKI) in intensive care units. During abdominal laparoscopic procedures, intraoperative insufflation pressures up to 15 mmHg are applied, to enable visualization and surgical manipulation but with the potential to compromise net renal perfusion. Despite the widely acknowledged renal arterial autoregulation, net arterial perfusion pressure is known to be narrow, and the effective renal medullary perfusion is disproportionately impacted by venous and lymphatic congestion. At present, the potential risk factors, mitigators and risk-stratification of AKI during surgical pneumoperitoneum formation received relatively limited attention among nephrologists and represent an opportunity to look beyond mere blood pressure and intake-output balances. Careful charting and reporting duration and extent of surgical pneumoperitoneum represents an opportunity for anesthesia teams to better communicate intraoperative factors affecting renal outcomes for the postoperative clinical teams. In this current article, the authors are integrating preclinical data and clinical experience to provide a better understanding to optimize renal perfusion during surgeries. Future studies should carefully consider intrabdominal insufflation pressure as a key variable when assessing outcomes and blood pressure goals in these settings.

Impact of operation duration on postoperative outcomes of minimally-invasive right colectomy

AIM

Operation time (OT) is a key operational factor influencing surgical outcomes. The present study aimed to analyse whether OT impacts on short-term outcomes of minimally-invasive right colectomies by assessing the role of surgical approach (robotic [RRC] or laparoscopic right colectomy [LRC]), and type of ileocolic anastomosis (i.e., intracorporal [IA] or extra-corporal anastomosis [EA]).

METHODS

This was a retrospective analysis of the Minimally-invasivE surgery for oncological Right ColectomY (MERCY) Study Group database, which included adult patients with nonmetastatic right colon adenocarcinoma operated on by oncological RRC or LRC between January 2014 and December 2020. Univariate and multivariate analyses were used.

RESULTS

The study sample was composed of 1549 patients who were divided into three groups according to the OT quartiles: (1) First quartile, <135 min (n = 386); (2) Second and third quartiles, 135-199 min (n = 731); and (3) Fourth quartile ≥200 min (n = 432). The majority (62.7%) were LRC-EA, followed by LRC-IA (24.3%), RRC-IA (11.1%), and RRC-EA (1.9%). Independent predictors of an OT ≥ 200 min included male gender, age, obesity, diabetes, use of indocyanine green fluorescence, and IA confection. An OT ≥ 200 min was significantly associated with an increased risk of postoperative noninfective complications (AOR: 1.56; 95% CI: 1.15-2.13; p = 0.004), whereas the surgical approach and the type of anastomosis had no impact on postoperative morbidity.

CONCLUSION

Prolonged OT is independently associated with increased odds of postoperative noninfective complications in oncological minimally-invasive right colectomy.

Mediators of Regional Kidney Perfusion during Surgical Pneumo-Peritoneum Creation and the Risk of Acute Kidney Injury—A Review of Basic Physiology

Acute kidney injury (AKI), especially if recurring, represents a risk factor for future chronic kidney disease. In intensive care units, increased intra-abdominal pressure is well-recognized as a significant contributor to AKI. However, the importance of transiently increased intra-abdominal pressures procedures is less commonly appreciated during laparoscopic surgery, the use of which has rapidly increased over the last few decades. Unlike the well-known autoregulation of the renal cortical circulation, medulla perfusion is modulated via partially independent regulatory mechanisms and strongly impacted by changes in venous and lymphatic pressures. In our review paper, we will provide a comprehensive overview of this evolving topic, covering a broad range from basic pathophysiology up to and including current clinical relevance and examples. Key regulators of oxidative stress such as ischemia-reperfusion injury, the activation of inflammatory response and humoral changes interacting with procedural pneumo-peritoneum formation and AKI risk will be recounted. Moreover, we present an in-depth review of the interaction of pneumo-peritoneum formation with general anesthetic agents and animal models of congestive heart failure. A better understanding of the relationship between pneumo-peritoneum formation and renal perfusion will support basic and clinical research, leading to improved clinical care and collaboration among specialists.

The role of Cushing's reflex and the vasopressin-mediated oligoanuric response to intracranial hypertension in patients with abdominal compartment syndrome

BACKGROUND

We examined the link between increased intra-abdominal pressure, intracranial pressure, and vasopressin release as a potential mechanism. Intra-abdominal pressure, produced by abdominal-cavity insufflation with carbon dioxide (CO₂) during laparoscopic abdominal procedures to facilitate visualization, is associated with various complications, including arterial hypertension and oliguria.

METHODS

Mean arterial pressure, optic nerve sheath diameter, measured as a proxy for intracranial pressure, plasma vasopressin, serum and urine osmolarity, and urine output were measured 4 times during laparoscopic sleeve gastrectomy in 42 patients: before insufflation with CO₂ (T₀); after insufflation to 15 cm water (H₂O) pressure, with 5 cm H₂O positive end-expiratory pressure (T₁); after positive end-expiratory pressure was raised to 10 cm H₂O (T₂); and after a return to the baseline state (T₃). Mean values at T₀ to T₃ and the directional consistency of changes (increase/decrease/ unchanged) were compared among the 4 data-collection points.

RESULTS

Statistically significant elevations (all P ≤ .001) were noted from T₀ to T₁ and from T₀ to T₂ in mean arterial pressure, optic nerve sheath diameter, and vasopressin, followed by decreases at T₃. For optic nerve sheath diameter and vasopressin, the increases at T₁ and T₂ occurred in 98% and 100% of patients, ultimately exceeding normal levels in 88 and 97%, respectively. Conversely, urine output fell from T₀ to T₁ and T₂ by 60.9 and 73.4%, decreasing in 88.1% of patients (all P < .001). Patients with class II obesity exhibited statistically greater increases in optic nerve sheath diameter and vasopressin, but statistically less impact on urine output, than patients with class III obesity.

CONCLUSION

Increased mean arterial pressure, intracranial pressure, and vasopressin release appear to be intermediary steps between increased intra-abdominal pressure and oliguria. Further research is necessary to determine any causative links between these physiological changes.

Effects of Pneumoperitoneum on Splanchnic Oxygenation during Abdominal Laparoscopic Surgery in Paediatric Patients: A prospective, Observational Study

Objective

Pneumoperitoneum can cause disruption in splanchnic perfusion. This study aims to investigate effects of pneumoperitoneum on splanchnic oxygenation during abdominal laparoscopic surgery in paediatric patients with NIRS (Near-Infrared Spectroscopy).

Material and methods

A total of 45 patients between 1 and 4 years of age with ASA physical status I–II and scheduled to undergo abdominal laparoscopic surgery under general anaesthesia were enrolled in this prospective, observational surgery. No premedication was used. Standard monitoring and regional splanchnic saturation (rSPcO₂), regional cerebral oxygen saturation (rScO₂) with NIRS were established before anaesthesia. Anaesthesia was induced with an inhalational agent and maintained with an oxygen/air mixture and sevoflurane. Peripheral oxygen saturation (SPO₂), rSPcO₂, rScO₂, heart rate (HR), mean arterial pressure (MAP), end tidal CO₂ (Et-CO₂), and insufflation pressure (IP) were continuously monitored during administration of anaesthesia and recorded. After intubation (baseline T0); before CO₂ insufflation induced pneumoperitoneum (PP) (T1); CO₂ PP insufflation (T2); 5 minutes after PP insufflation (T3); 10 minutes after PP insufflation (T4); 15 minutes after PP insufflation (T5); 20 minutes after PP insufflation (T6); 30 minutes after PP insufflation (T7), 60 minutes after PP insufflation (T8), and after desufflation (T9). Bradycardia and hypotension were recorded. Paracetamol IV 10 mg kg⁻¹ was applied for post-operative analgesia. p<0.05 wasconsidered significant.

Results

HR, rScO₂, and rSPcO₂ decreased at all measured time intervals when compared to T0 (p<0.01) MAP decreased at T1 compared to T0 (p<0.001). Et-CO₂ increased at T3-T4-T5-T6 compared to T0 (p<0.001).

Conclusion

We found that pneumoperitoneum reduced splanchnic oxygenation during laparoscopic abdominal surgery in paediatric patients, which was measured using NIRS.

Effects of low- and high-pressure carbon dioxide pneumoperitoneum on intracranial pressure during laparoscopic cholecystectomy

BACKGROUND

Laparoscopic surgeries are a risk factor for raised intracranial **pressure and neurological complications. Even though rare, the consequences may be severe.

METHODS

One hundred and one patients of laparoscopic cholecystectomy were enrolled and were randomized into two groups: low-pressure 8 mm Hg (Group A) and high-pressure 14 mm Hg (Group B) carbon dioxide pneumoperitoneum during surgery. Fifty patients were in group A and 51 patients were in group B. Intracranial pressure was measured by measuring the optic nerve sheath diameter (ONSD) using ultrasound examination. Baseline ONSD was recorded followed by ONSD recording at various intervals: at the induction of anesthesia; 30 min, 45 min, at the end of surgery; and 30 min post surgery.

RESULTS

The groups were comparable in terms of demographics and comorbidities. The mean age of group A was 45 years and for group B it was 45.75 years. Most common indication for surgery was symptomatic gall stone disease. Baseline ONSD in group A was 0.427 ± 0.0459 mm, whereas it was 0.412 ± 0.0412 mm in group B. There was a significant rise of ONSD (p < 0.05) 30 min after induction of pneumoperitoneum and up to 30 min post anesthesia. In the low-pressure group 7 (14%) patients had a significant rise of ICP, whereas in the high-pressure group 20 (39%) patients had a significant rise of ICP (p < 0.05).

CONCLUSIONS

High-pressure pneumoperitoneum causes significant rise in intracranial pressure in comparison to low-pressure pneumoperitoneum during laparoscopic cholecystectomy, which can be monitored by ONSD measurement by ultrasound examination and is totally non-invasive.

The Cushing reflex and the vasopressin-mediated hemodynamic response to increased intracranial pressure during acute elevations in intraabdominal pressure

BACKGROUND

Abdominal compartment syndrome has been linked to detrimental hemodynamic side effects that include increased intracranial pressure and diminished renal function, but the mechanisms behind this continue to be elucidated. In this study, we sought to investigate any direct association between acute elevations in intra-abdominal pressure and intracranial hypertension during experimentally induced abdominal compartment syndrome and between acutely elevated intracranial pressure and the hemodynamic response that might be elicited by a vasopressin-induced Cushing reflex affecting urine osmolality and urine output. The aim of this study is to explain the Cushing reflex and the vasopressin-mediated hemodynamic response to intracranial pressure during acute elevations in intra-abdominal pressure.

METHODS

We measured intra-abdominal pressure, intrathoracic pressure, optic nerve sheath diameter as an indirect sign of intracranial pressure, vasopressin levels in blood, urine osmolality, and urine output at 4 time points during surgery in 16 patients undergoing sleeve gastrectomy for morbid obesity. Values for the 4 time points were compared by repeated-measures analysis of variance.

RESULTS

More than 50-fold elevations in serum vasopressin paralleled increases in optic nerve sheath diameter, rising throughout prepneumoperitoneum and tapering off afterward, in conjunction with a marked decrease in urine but not serum osmolality. Mean arterial pressure rose transiently during pneumoperitoneum without elevated positive end-expiratory pressure but was not significantly elevated thereafter.

CONCLUSIONS

These findings support our hypothesis that the oliguric response observed in abdominal compartment syndrome might be the result of the acutely elevated intra-abdominal pressure triggering increased intrathoracic pressure, decreased venous outflow from the central nervous system, increased intracranial pressure, and resultant vasopressin release via a Cushing reflex.

Changes in cerebral and renal oxygenation during laparoscopic pyloromyotomy

Although a laparoscopic approach may be preferred over open procedures for abdominal surgery, there are limited data on the effect of laparoscopic procedures on cerebral and renal oxygenation in neonates and young infants. Here, we evaluated the effect in neonates and infants. In this two-center prospective observational study, we evaluated changes in cerebral and renal regional oxygen saturation (rSO₂) in infants during laparoscopic pyloromyotomy. Intraoperative hemodynamic and respiratory parameters and rSO₂ were recorded. For the primary outcome, these parameters were compared at incision and at the end of pneumoperitoneum. The study cohort included 25 infants with a mean age of 40 ± 10 days and weight of 4.0 ± 0.6 kg. IAP at the beginning of laparoscopy was 10 ± 2 mmHg (range 7-15 mmHg). Although both cerebral and renal rSO₂ decreased from incision compared to the end of laparoscopy, the decrease reached statistical significance only for cerebral rSO₂ (81 ± 12 to 76 ± 16, p = 0.033). Similarly, the increase in fractional tissue oxygen extraction (FTOE) was only statistically significant for cerebral FTOE (0.18 ± 0.12 to 0.23 ± 0.16, p = 0.037). No change in hemodynamic or respiratory parameters was found. Although there was a decrease in cerebral rSO₂ and increase in cerebral FTOE during pneumoperitoneum, the values did not decrease below those noted before anesthetic induction.

Effects of pneumoperitoneum and Trendelenburg position on intracranial pressure assessed using different non-invasive methods

BACKGROUND

The laparoscopic approach is becoming increasingly frequent for many different surgical procedures. However, the combination of pneumoperitoneum and Trendelenburg positioning associated with this approach may increase the patient's risk for elevated intracranial pressure (ICP). Given that the gold standard for the measurement of ICP is invasive, little is known about the effect of these common procedures on ICP.

METHODS

We prospectively studied 40 patients without any history of cerebral disease who were undergoing laparoscopic procedures. Three different methods were used for non-invasive estimation of ICP: ultrasonography of the optic nerve sheath diameter (ONSD); transcranial Doppler-based (TCD) pulsatility index (ICP_PI); and a method based on the diastolic component of the TCD cerebral blood flow velocity (ICP_FVd). The ONSD and TCD were measured immediately after induction of general anaesthesia, after pneumoperitoneum insufflation, after Trendelenburg positioning, and again at the end of the procedure.

RESULTS

The ONSD, ICP_FVd, and ICP_PI increased significantly after the combination of pneumoperitoneum insufflation and Trendelenburg positioning. The ICP_FVd showed an area under the curve of 0.80 [95% confidence interval (CI) 0.70-0.90] to distinguish the stage associated with the application of pneumoperitoneum and Trendelenburg position; ONSD and ICP_PI showed an area under the curve of 0.75 (95% CI 0.65-0.86) and 0.70 (95% CI 0.58-0.81), respectively.

CONCLUSIONS

The concomitance of pneumoperitoneum and the Trendelenburg position can increase ICP as estimated with non-invasive methods. In high-risk patients undergoing laparoscopic procedures, non-invasive ICP monitoring through a combination of ONSD ultrasonography and TCD-derived ICP_FVd could be a valid option to assess the risk of increased ICP.

Renal Perfusion and Function during Pneumoperitoneum: A Systematic Review and Meta-Analysis of Animal Studies

Both preclinical and clinical studies indicate that raised intra-abdominal pressure (IAP) associated with pneumoperitoneum during laparoscopic surgical procedures can cause renal damage, the severity of which may be influenced by variables such as pressure level and duration. Several of these variables have been investigated in animal studies, but synthesis of all preclinical data has not been performed. This systematic review summarizes all available pre-clinical evidence on this topic, including an assessment of its quality and risk of bias. We performed meta-analysis to assess which aspects of the pneumoperitoneum determine the severity of its adverse effects. A systematic search in two databases identified 55 studies on the effect of pneumoperitoneum on renal function which met our inclusion criteria. There was high heterogeneity between the studies regarding study design, species, sex, pressure and duration of pneumoperitoneum, and type of gas used. Measures to reduce bias were poorly reported, leading to an unclear risk of bias in the majority of studies. Details on randomisation, blinding and a sample size calculation were not reported in ≥80% of the studies. Meta-analysis showed an overall increase in serum creatinine during pneumoperitoneum, and a decrease in urine output and renal blood flow. Subgroup analysis indicated that for serum creatinine, this effect differed between species. Subgroup analysis of pressure level indicated that urine output decreased as IAP level increased. No differences between types of gas were observed. Data were insufficient to reliably assess whether sex or IAP duration modulate the effect of pneumoperitoneum. Four studies assessing long-term effects indicated that serum creatinine normalized ≥24 hours after desufflation of pneumoperitoneum at 15mmHg. We conclude that harmful effects on renal function and perfusion during pneumoperitoneum appear to be robust, but evidence on long-term effects is very limited. The reliability and clinical relevance of these findings for healthy patients and patients at high risk of renal impairment remain uncertain. We emphasize the need for rigorous reporting of preclinical research methodology, which is of vital importance for clinical translation of preclinical data.

Minimally Invasive Surgery for Live Kidney Donors: Techniques and Challenges

Live kidney donation is assuming an increasingly prominent role in kidney transplantation programs. The traditional operative approach has been through an incision in the upper quadrant of the abdomen or in the loin, with the attendant potential postoperative complications associated with a large surgical wound. These problems may act as disincentives to prospective donors. The introduction of laparoscopic donor surgery in 1995 heralded a new era offering reduced postoperative pain and improved cosmetic result. It is hoped that these benefits may counter some disincentives and thereby increase donation rates. Three minimal-access approaches and their advantages and disadvantages are described: classical laparoscopic, hand-assisted laparoscopic, and retroperitoneoscopic surgery. Published reports indicate extensive experience with the first 2 of these approaches and less experience with the latter. All 3 approaches present technical, physiological, and anatomical challenges in the context of retrieving an organ that is fit for transplantation. For minimal-access surgery to be accepted as the procedure of choice for live kidney donors, it must be demonstrated that morbidity is not transferred from donor to recipient when these techniques are used. Some concerns about these procedures are addressed. High-level evidence in the form of randomized controlled trials is generally lacking, but experiences of surgeons and patients suggest that, with appropriate modifications, these techniques are safe for both donors and allografts and also benefit donors' recovery.

The relationship between intracranial pressure and obesity: an ultrasonographic evaluation of the optic nerve

BACKGROUND

Measurements of optic nerve sheath diameter (ONSD) with noninvasive ocular ultrasonography have been shown to be accurate in determining increased intracranial pressure. Obesity is associated with chronic increases in intraabdominal pressure that could consequently result in intracranial hypertension. By utilizing ONSD ultrasonographic measurements, we compare the difference that may exist between obese and non-obese patients.

STUDY DESIGN

We prospectively collected data from patients who underwent laparoscopic procedures in the supine position between July 2013 and March 2014. Ophthalmic pathology was not present in any patient. Ultrasonographic measurement of the ONSD was obtained sagittally with a 12-MHz transducer 3 mm from its origin. The measurements were taken at 0, 15, and 30 min, and at the end of surgery.

RESULTS

There were 62 subjects, 28 females (45.2 %) and 34 males (54.8 %), with a mean age of 44.22 ± 10.44 years (range 23-66). Forty-eight percent of patients were non-obese, and 52 % of patients were obese. The mean body mass index was 30.70 ± 7.61 kg/m(2) (range 20.0-59.5). The mean ONSD of non-obese and obese patients was 4.7 and 5.5 mm at baseline (p = 0.01), 5.4 and 6.2 mm at 15 min (p = 0.01), 5.8 and 6.6 mm at 30 min (p = 0.01), and 5.1 and 5.7 mm after deflation of pneumoperitoneum (p = 0.03), respectively.

CONCLUSIONS

Utilizing a noninvasive method to measure the ONSD, a chronic increase in intracranial pressure in obese patients was demonstrated. The increase in the ONSD during laparoscopic procedures reflects a temporary increase in the intracranial pressure from baseline.

Intraoperative non invasive intracranial pressure monitoring during pneumoperitoneum: a case report and a review of the published cases and case report series

Non-invasive measurement of ICP (nICP) can be warranted in patients at risk for developing increased ICP during pneumoperitoneum (PP). Our aim was to assess available data on the application of nICP monitoring during these procedures and to present a patient assessed with an innovative combination of noninvasive tools. Literature review of nICP assessment during PP did not find any studies comparing different methods intraprocedurally and only few studies of any nICP monitoring were available: transcranial Doppler (TCD) studies used the pulsatility index (PI) as an estimator of ICP and failed to detect a significant ICP increase during PP, whereas two out of three optic nerve sheath diameter (ONSD) studies detected a statistically significant ICP increase. In the case study, we describe a 52 year old man with a high grade thalamic glioma who underwent urgent laparoscopic cholecystectomy. Considering the high intraoperative risk of developing intracranial hypertension, he was monitored through parallel ONSD ultrasound measurement and TCD derived formulae (flow velocity diastolic formula, FVdnICP, and PI). ONSD and FVdnICP methods indicated a significant ICP increase during PP, whereas PI was not significantly increased. Our experience, combined with the literature review, seems to suggest that PI might not detect ICP changes in this context, however we indicate a possible interest of nICP monitoring during PP by means of ONSD and of TCD derived FVdNICP, especially for patients at risk for increased ICP.

What is the evidence for the use of low-pressure pneumoperitoneum? A systematic review

Background

Laparoscopic surgery has several advantages when compared to open surgery, including faster postoperative recovery and lower pain scores. However, for laparoscopy, a pneumoperitoneum is required to create workspace between the abdominal wall and intraabdominal organs. Increased intraabdominal pressure may also have negative implications on cardiovascular, pulmonary, and intraabdominal organ functionings. To overcome these negative consequences, several trials have been performed comparing low- versus standard-pressure pneumoperitoneum.

Methods

A systematic review of all randomized controlled clinical trials and observational studies comparing low- versus standard-pressure pneumoperitoneum.

Results and conclusions

Quality assessment showed that the overall quality of evidence was moderate to low. Postoperative pain scores were reduced by the use of low-pressure pneumoperitoneum. With appropriate perioperative measures, the use of low-pressure pneumoperitoneum does not seem to have clinical advantages as compared to standard pressure on cardiac and pulmonary function. Although there are indications that low-pressure pneumoperitoneum is associated with less liver and kidney injury when compared to standard-pressure pneumoperitoneum, this does not seem to have clinical implications for healthy individuals. The influence of low-pressure pneumoperitoneum on adhesion formation, anastomosis healing, tumor metastasis, intraocular and intracerebral pressure, and thromboembolic complications remains uncertain, as no human clinical trials have been performed. The influence of pressure on surgical conditions and safety has not been established to date. In conclusion, the most important benefit of low-pressure pneumoperitoneum is lower postoperative pain scores, supported by a moderate quality of evidence. However, the quality of surgical conditions and safety of the use of low-pressure pneumoperitoneum need to be established, as are the values and preferences of physicians and patients regarding the potential benefits and risks. Therefore, the recommendation to use low-pressure pneumoperitoneum during laparoscopy is weak, and more studies are required.

Impact of controlled intraabdominal pressure on the optic nerve sheath diameter during laparoscopic procedures

BACKGROUND

Acute elevations of intraabdominal pressure (IAP) are seen in many clinical scenarios with a consequent elevation in intracranial pressure (ICP). With the optic nerve sheath (ONS) being a part of the dura mater and the optic nerve surrounded by cerebral spinal fluid, a change in pressure within the subarachnoid space would be detected by ultrasonography, and invasive methods could be avoided. The study objective was to evaluate ultrasonographic modifications observed on the optic nerve sheath diameter during acute elevations of IAP in patients undergoing laparoscopic procedures.

STUDY DESIGN

We prospectively collected data from patients who underwent laparoscopic procedures between July and August 2013. The optic nerve sheath diameter was measured sagittally with a 12-MHz transducer. The measurements were obtained at baseline, 15 and 30 min, and at the end of surgery.

RESULTS

There were 16 females (36.4%) and 28 males (63.6%), with a mean age of 44.22 ± 10.44 years (range 23-66) and body mass index of 29.45 ± 6.53 kg/m(2) (range 21-39). The mean optic nerve sheath diameter was 4.8 ± 1.0 mm at baseline, 5.5 ± 1.1 mm at 15 min, 5.9 ± 1.0 mm at 30 min, and 5.1 ± 1.2 mm after deflation of pneumoperitoneum. The diameter increased significantly at 15 min by a median of 0.6 mm (interquartile range 0.3, 0.8; p < 0.0001) and at 30 min by a median of 1.0 mm (interquartile range 0.7, 1.4; p < 0.0001), returning close to baseline after surgery.

CONCLUSION

The acute elevation in IAP during laparoscopy significantly increased the optic nerve sheath diameter. The changes in the ONSD reflect a temporary and reversible increase in the ICP due to the acute elevation of IAP.

The influence of intra-abdominal hypertension on the central nervous system: current insights and clinical recommendations, is it all in the head?

INTRODUCTION

Intra-abdominal hypertension (IAH) and abdominal compartment syndrome are a common occurrence in ICU patients. The deleterious effects of IAH on organ function are well known and increasingly appreciated in recent years, especially where renal and respiratory function are concerned.

METHODS

This review will focus on the available literature from the last years. A Medline and PubMed search was performed in order to find an answer to the question "What is the impact of increased IAP on neurologic function in the critically ill?"

RESULTS

The amount of data on the influence of IAH on the central nervous system is more scarce, but several animal and human studies have demonstrated a clear correlation between intra-abdominal pressure (IAP) and intracranial pressure (ICP). This correlation is probably due to transmission of the increased IAP to the thorax leading to increased intrathoracic, pleural pressure and central venous pressure, decreased venous return from the brain and increased ICP. This hypothesis is supported by the observation that the increase in ICP is abolished when a sternotomy and pleuropericardotomy are performed, and by the fact that abdominal decompression has produced good results in treating refractory intracranial hypertension (ICH) in patients with both IAH and ICH.

CONCLUSIONS

A close relationship between IAP and ICP has been observed in several animal and human studies. The clinical impact of this association is dependent on the baseline ICP and the compensatory reserve of the patient. Some studies have reported good results in treating refractory ICH by abdominal decompression in patients with concomitant IAH. Monitoring of IAP and ICP in risk patients is essential.

A prospective assessment of renal oxygenation in children undergoing laparoscopy using near-infrared spectroscopy

BACKGROUND

This study was designed to determine whether a decrease in renal oxygenation occurs during CO2 pneumoperitoneum in children with normal renal function undergoing laparoscopy.

METHODS

Near infrared spectroscopy (NIRS) probes were applied to both the lateral flank (T10-L2) and lateral cerebral area of all patients with normal renal function undergoing a laparoscopic procedure. Information was recorded in 5-s intervals for 15-min before, during, and for 15-min after pneumoperitoneum insufflation and desufflation. Simultaneously, additional hemodynamic parameters (arterial saturation, mean arterial pressure, end tidal CO2, and urine output) were recorded every 5-min. Pneumoperitoneum pressures used were: 0-1 month old, <6 mmHg; 2-12 months old, <8 mmHg; 1-2 years old, <10 mmHg, and 2-8 years old, <12 mmHg. The lowest possible pressure was used to obtain adequate vision.

RESULTS

Twenty-nine patients were enrolled in the study. Renal regional oxygen saturation (rSO2) did not decrease significantly between baseline (preinsufflation), insufflation, and desufflation of the pneumoperitoneum (p = 0.343). Meta-analysis of this data demonstrated a pooled weighted difference of -1.4 (-3.5 to 0.54), confirming no significant change. A significant increase in cerebral rSO2 occurred during the insufflation period of the CO2 pneumoperitoneum (p = 0.001). Heart rate (F = 11.05; p < 0.001) and mean arterial pressure (MAP) (F = 19.2; p < 0.001) also increased significantly during the laparoscopy. No significant correlation was identified between fluid input and urine output during the laparoscopy (r = 0.012; p = 0.953).

CONCLUSIONS

Renal hypoxia does not occur during laparoscopic surgery in children if the minimum age-appropriate intra-abdominal pressures are used. Alternative causes must account for the oliguria and anuria demonstrated in children undergoing laparoscopy.

Transcranial Doppler monitoring of middle cerebral flow velocity in a patient with a ventriculoperitoneal shunt undergoing laparoscopy

Laparoscopic surgery is possibly associated with a risk of intracranial pressure (ICP) increase due to pneumoperitoneum in patients with ventriculoperitoneal shunts (VPS). Invasive techniques for shunt pressure monitoring are not routinely used because of the possible complications. Transcranial Doppler (TCD) is a non-invasive, safe method which gives accurate information about blood-flow velocities in basal cerebral arteries and indirectly about the ICP. Moreover it is inexpensive and simple in use. We report the use of TCD for middle cerebral flow velocity monitoring in a patient with a VPS who underwent laparoscopic surgery. In the case we present, during 60 min of pneumoperitoneum, TCD showed a sustained, but not clinically significant increase of the Pulsatility Index, with a recorded maximum change of 31 %. We consider that the use of TCD may increase the safety of laparoscopic procedures in patients with preexisting VPS.

Understanding Intra-Abdominal Hypertension

Received November 10, 2009. Received Revised June 17, 2010. Submitted June 21, 2010. Intra-abdominal hypertension (IAH) and abdominal compartment syndrome (ACS) are highly morbid conditions that are common and underrecognized in the intensive care unit. Intra-abdominal hypertension affects the critically ill patient population and is not solely limited to the trauma and surgical subgroups. The recognition of IAH and ACS as distinct clinical states has become more apparent. Extensive bench and clinical research has shed significant light into the definition, incidence, etiology, physiology, clinical manifestations, and treatment strategies. Although further research into this morbid condition is needed, improvement in recognition is a critical first step. This review aims to scrutinize the basic science and clinical literature available on this condition in a surgically focused, organ-system-based approach.

Open and laparoscopic donor nephrectomy: activity and outcomes from all Australasian transplant centers

BACKGROUND

Laparoscopic donor nephrectomy (LapDN) has been widely adopted despite a lack of randomized trials comparing recipient outcomes with open surgery. Review of registry data now seems the most realistic mechanism to compare outcomes. The Australia and New Zealand Dialysis and Transplant Registry prospectively captures data on all renal transplants performed in Australia and New Zealand including long-term follow-up of recipients. AIM.: To compare graft outcomes among recipient of kidneys from donors undergoing nephrectomy using open and laparoscopic techniques, through analysis of the Australia and New Zealand Dialysis and Transplant Registry after the introduction of laparoscopic donor surgery in Australia and New Zealand in 1997.

METHODS

Operative technique data for live donor transplants were collected from all surgeons performing live kidney donation procedures from May 1997 to December 2003; the outcomes of all live donor transplants were examined with follow-up to December 2007. Donor and recipient demographic variables and graft outcomes were compared between the laparoscopic and the open donor groups.

RESULTS

One thousand four hundred seventy-four live donor transplants were performed in 27 transplant centers. Of these, 315 (21%) were performed laparoscopically in 11 centers. Nineteen laparoscopic cases (6%) were converted to open. Total ischemic time was longer in the LapDN group (3.16 hr) than in the open donor group (1.61 hr, P<0.0001). The LapDN group experienced a lower incidence of rejection episodes (29.2% vs. 38.6%, P=0.002). Delayed graft function and technical failure rates were statistically equal across the groups. There were a total of 242 graft failures (175 graft losses and 67 deaths with a functioning graft, NS). Among surviving grafts, there was no consistent difference in serum creatinine at any time point. Graft and patient survivals were similar in both groups during 10-year follow-up.

CONCLUSION

This study suggests that there is no difference in short- or long-term recipient outcomes for open and laparoscopic live donor nephrectomy.

Laparoscopic cholecystectomy in a morbidly obese patient with Chiari I malformation and craniocervical anomalies

Chiari I malformation is the downward herniation of cerebellar tonsils through the foramen magnum, and is frequently associated with craniocervical anomalies. Laparoscopic surgery can cause an increase in intracranial pressure due to the obstruction of the foramen magnum. The successful administration of general anesthesia in a 50-year-old, morbidly obese woman with a difficult airway, scheduled for laparoscopic cholecystectomy, who was incidentally diagnosed with Chiari I malformation associated with craniocervical anomalies, is presented.

Fast-track surgery in laparoscopic radical prostatectomy: basic principles

Fast-track surgery describes innovative treatment concepts ensuring a faster convalescence phase. The aim of this study was to allow hospital discharge 3 days after surgery without additional complications in patients receiving LRPE for localized prostate cancer. Twenty-five patients each were randomized in the study groups to verify if a fast-track regimen could be transferred into clinical routine. The perioperative data, early complications, hospital stay as well as readmission rate were analyzed. The mean postoperative stay was 3.6 days in the fast-track group versus 6.7 days in the conventional group. The overall complications were significantly less in the fast-track procedure. The readmission rate was low and not significant. Patients receiving an LRPE benefit from a suitable fast-track concept. The postoperative hospital stay could be shortened nearly by half with a significantly decreased overall complication rate. Thus, fast-track concepts might contribute to saving resources in the long term. However, more evidence based on larger prospective trials is needed to achieve optimal quality of life for patients perioperatively.

Effect of pneumoperitoneum on renal perfusion and function: a systematic review

BACKGROUND

The precise physiologic consequences of insufflating carbon dioxide into the abdominal cavity during laparoscopy are not yet fully understood. This systematic review aimed to investigate whether pneumoperitoneum results in decreased renal blood flow (RBF) or renal function.

METHODS

A literature search was conducted electronically using Medline, Embase, and the Cochrane libraries on 1 July 2005. Various combinations of the medical subject headings--renal blood flow, pneumoperitoneum, renal function, and laparoscopy--were searched in all three databases. Reference lists from articles fulfilling the search criteria were used to identify additional articles.

RESULTS

The literature search retrieved 20 articles concerning RBF and 25 articles concerning renal function during pneumoperitoneum. It was found that 17 of the 20 studies identified a decrease in RBF, and 20 of the 25 studies identified a decrease in renal function during pneumoperitoneum.

CONCLUSION

There appears to be sufficient evidence to conclude that both renal function and RBF are decreased during pneumoperitoneum. The magnitude of the decrease is dependent on factors such as preoperative renal function, level of hydration, level of pneumoperitoneum, patient positioning, and duration of pneumoperitoneum.

Comportamento da pressão intracraniana, da perfusão cerebral e dos parâmetros hemodinâmicos durante a síndrome do compartimento abdominal em cães

OBJETIVO: Estudar as alterações hemodinâmicas e as repercussões sobre o sistema nervoso central ocasionados pela síndrome do compartimento abdominal. MÉTODO: Utilizou-se cães sem raça definida submetidos à anestesia geral e monitorização das pressões arterial média(PAM), intracraniana(PIC), de perfusão cerebral(PPC), da artéria pulmonar(PAP) e venosa central(PVC), do débito cardíaco(DC) e da freqüência cardíaca(FC). Aumentou-se a pressão intra-abdominal(PIA) para níveis de 10,20,30 e 40cmH2O . Após atingir-se nível PIA=40cmH2O realizou-se a descompressão cirúrgica da cavidade abdominal. Em cada etapa realizou-se a medida dos parâmetros PIA, PIC, PAM, PPC, PVC e DC. RESULTADOS: Observou-se que o aumento da PIA causou as seguintes alterações fisiológicas: aumento progressivo da PIC; aumento da PAM até PIA=20cmH2O e diminuição progressiva da mesma após PIA= 40cmH2O; aumento da PPC até PIA=10cmH2O e diminuição progressiva da mesma após PIA= 30cmH2O; aumento progressivo da PVC; diminuição progressiva do DC após PIA= 30cmH2O; Após a descompressão da cavidade, notou-se o retorno da PIC, PAM, PPC, PVC e do DC para valores próximos aos dos iniciais (antes do aumento da PIA). CONCLUSÕES: Concluímos que o aumento da PIA provocou alterações nos sistemas cardiovascular e nervoso central, que foram revertidas após a descompressão cirúrgica da cavidade abdominal.

Is it wise not to think about intraabdominal hypertension in the ICU?

PURPOSE OF REVIEW

This review focuses on the available literature published in the past 2 years. MEDLINE and PubMed searches were performed using intraabdominal pressure, intraabdominal hypertension, and abdominal compartment as search items. The aim was to find an answer to the question: "Is it wise not to measure or even not to think about intraabdominal hypertension in ICU?"

RECENT FINDINGS

It is difficult to find a good gold standard for intraabdominal pressure measurement. Bladder pressure can be used as an intraabdominal pressure estimate provided it is measured in a reproducible way. Automated continuous intraabdominal pressure monitoring has recently become available. Key messages are (1). body mass index and fluid resuscitation are independent predictors of intraabdominal hypertension; (2). intraabdominal hypertension increases intrathoracic, intracranial, and intracardiac filling pressures; (3). transmural or transabdominal filling pressures combined with volumetric parameters better reflect preload; (4). volumetric target values need to be corrected for baseline ejection fractions; (5). intraabdominal hypertension decreases left ventricular, chest wall and total respiratory system compliance; (6). best positive end-expiratory pressure can be set to counteract intraabdominal pressure; (7). acute respiratory distress syndrome definitions should take into account best positive end-expiratory pressure and intraabdominal pressure but not wedge pressure; (8). lung protective strategies should aim at deltaPplat (plateau pressure - intraabdominal pressure); (9). intraabdominal hypertension causes atelectasis and increases extravascular lung water; (10). intraabdominal hypertension is an independent predictor of acute renal failure; (11). monitoring of abdominal perfusion pressure can be useful; and (12). intraabdominal hypertension triggers bacterial translocation and multiple organ system failure.

SUMMARY

The answer is that it is unwise not to measure intraabdominal pressure in the ICU or even not to think about it.