Latest developments in peri-operative monitoring of the high-risk major surgery patient. Int J Surg. 2010;8:90-99. [PMID: 20079469 DOI: 10.1016/j.ijsu.2009.12.004]

The relationship between perioperative central venous oxygen saturation and postoperative complications in highly invasive gastroenterological surgery

Purpose

Operations for malignant diseases of the bile duct, pancreas, and esophagus are the most invasive gastroenterological surgeries. The frequency of complications after these surgeries is high, which affects the postoperative course and mortality. In patients who undergo these types of surgeries, continuous monitoring of the perioperative central venous oxygen saturation (ScvO2) is possible via a central venous catheter. We aimed to investigate the relationship between continuously monitored perioperative ScvO2 values and postoperative complications.

Methods

The medical records of 115 patients who underwent highly invasive gastroenterological surgeries and ScvO2 monitoring from April 2012 to March 2014 were analyzed. Sixty patients met the inclusion criteria, and their ScvO2 levels were continuously monitored perioperatively. The relationship between ScvO2 levels and major postoperative complications, defined as Clavien-Dindo grade ≥ III, was examined using uni- and multivariate analysis.

Results

Thirty patients developed major postoperative complications. The adequate cut-off value derived from receiver operating curves of the postoperative average ScvO2 levels for predicting major complications was 75%. Multivariate analysis revealed that low average postoperative ScvO2 levels (p = 0.016) and blood loss ≥ 1000 mL (p = 0.039) were significant predictors of major postoperative complications.

Conclusions

Low perioperative ScvO2 values were associated with an increased risk of major postoperative complications. Continuous ScvO2 monitoring will help prevent postoperative complications.

Influence of different intraoperative fluid management on postoperative outcome after abdominal tumours resection

BACKGROUND

Intraoperative fluid management is a crucial aspect of cancer surgery, including colorectal surgery and pancreatoduodenectomy. The study tests if intraoperative multimodal monitoring reduces postoperative morbidity and duration of hospitalisation in patients undergoing major abdominal surgery treated by the same anaesthetic protocols with epidural analgesia.

PATIENTS AND METHODS

A prospective study was conducted in 2 parallel groups. High-risk surgical patients undergoing major abdominal surgery were randomly selected in the control group (CG), where standard monitoring was applied (44 patients), and the protocol group (PG), where cerebral oxygenation and extended hemodynamic monitoring were used with the protocol for intraoperative interventions (44 patients).

RESULTS

There were no differences in the median length of hospital stay, CG 9 days (interquartile range [IQR] 8 days), PG 9 (5.5), p = 0.851. There was no difference in postoperative renal of cardiac impairment. Procalcitonin was significantly higher (highest postoperative value in the first 3 days) in CG, 0.75 mcg/L (IQR 3.19 mcg/L), than in PG, 0.3 mcg/L (0.88 mcg/L), p = 0.001. PG patients received a larger volume of intraoperative fluid; median intraoperative fluid balance +1300 ml (IQR 1063 ml) than CG; +375 ml (IQR 438 ml), p < 0.001.

CONCLUSIONS

There were significant differences in intraoperative fluid management and vasopressor use. The median postoperative value of procalcitonin was significantly higher in CG, suggesting differences in immune response to tissue trauma in different intraoperative fluid status, but there was no difference in postoperative morbidity or hospital stay.

Short-term outcomes of perioperative glucocorticoid administration in patients undergoing liver surgery: a systematic review and meta-analysis of randomised controlled trials

OBJECTIVE

The purpose of this systematic review and meta-analysis was to investigate whether glucocorticoid might be beneficial after hepatectomy.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

PubMed, Embase, Cochrane Library and Web of Science.

ELIGIBILITY CRITERIA

We included studies assessing the efficacy of perioperative glucocorticoid administration in patients undergoing liver surgery.

DATA EXTRACTION AND SYNTHESIS

Four data bases were retrieved for all randomised controlled trials. We considered postoperative complications, hospital stay and postoperative chemistry evaluations as outcomes. Pooled effects of dichotomic variables were expressed as relative risk (RR) with a 95% CI. The mean difference was used for continuous variables and an inverse variance statistical method was adopted.

RESULTS

Fourteen studies with 1205 patients were included. Lower risk of overall complications was associated with glucocorticoid (RR, 0.77; 95% CI 0.64 to 0.92), while no difference was found in hospital stay (RR, 0.02; 95% CI -0.47 to 0.51). There were also improvements in postoperative chemistry evaluations including interleukin 6 on day 1 and 3, C reactive protein on day 1, 2 and 3, international normalised ratio on day 2, total bilirubin on day 1, 2, 3 and 5, albumin on day 1.

CONCLUSION

Current evidence indicated that perioperative glucocorticoid administration for patients undergoing hepatectomy reduced the risk of overall complications with inhibited postoperative inflammatory response and improved postoperative liver function.

PROSPERO REGISTRATION NUMBER

CRD42022307533.

Design of an interface for teaching cardiovascular physiology to anesthesia clinicians with a patient simulator connected to a minimally invasive cardiac output monitor (LiDCO rapid®)

Cardiovascular physiology can be simulated in patient simulators but is limited to the simulator monitor curves and parameters, missing some important data that today is known as essential to fluid management and therapeutic decision in critical ill and high-risk surgical patients. Our main objective was to project and implement a unidirectional communication channel between a pre-existing patient simulator and a minimally invasive cardiac output monitor (LiDCO rapid®); a monitor that connects to real patients and interprets the arterial wave. To connect the patient simulator to the hemodynamic monitor, firstly, we had to assess both systems and design a communication channel between them. LiDCO monitor accepts as an input an analog voltage varying between 0 V and 5 V and that every volt is directly proportional to a blood pressure (mmHg) value ranging from 0 mmHg (0 V) to 500 mmHg (5 V). A Raspberry Pi 0 (Rpi0) with a WIFI chip integrated was needed and added to a digital analogue converter connected to the board. We designed a system that allowed us to collect, interpret and modify data, and feed it to the LiDCO rapid® monitor. We had developed a Python® script with three independent threads and a circular buffer to handle the data transmission between both systems. The LiDCO hemodynamic monitor successfully received data sent from our setup like a real patient arterial wave pulse and interpreted it to estimate several hemodynamic parameters, as cardiac output, stroke volume, systemic vascular resistance, pulse pressure variation, and stroke volume variation. The connection between the patient simulator and the LiDCO monitor is being used to create arterial curves and other hemodynamic parameters for clinical scenarios where residents and anesthesiologists can simulate a variety of unstable hemodynamic conditions, preparing them to face similar situations with real patients in a safe environment and with their own monitors.

A Review of Goal-Directed Cardiopulmonary Bypass Management in Pediatric Cardiac Surgery

Cardiopulmonary bypass perfusion management significantly affects postoperative outcomes. In recent years, the principles of goal-directed therapy have been applied to the field of cardiothoracic surgery to improve patient outcomes. Goal-directed therapy involves continuous peri- and postoperative monitoring of vital clinical parameters to tailor perfusion to each patient's specific needs. Closely measured parameters include fibrinogen, platelet count, lactate, venous oxygen saturation, central venous oxygen saturation, mean arterial pressure, perfusion flow rate, and perfusion pulsatility. These parameters have been shown to influence postoperative fresh frozen plasma transfusion rate, coagulation state, end-organ perfusion, and mortality. In this review, we discuss the recent paradigm shift in pediatric perfusion management toward goal-directed perfusion.

Prediction of postoperative outcomes using intraoperative hemodynamic monitoring data

Major surgeries can result in high rates of adverse postoperative events. Reliable prediction of which patient might be at risk for such events may help guide peri- and postoperative care. We show how archiving and mining of intraoperative hemodynamic data in orthotopic liver transplantation (OLT) can aid in the prediction of postoperative 180-day mortality and acute renal failure (ARF), improving upon predictions that rely on preoperative information only. From 101 patient records, we extracted 15 preoperative features from clinical records and 41 features from intraoperative hemodynamic signals. We used logistic regression with leave-one-out cross-validation to predict outcomes, and incorporated methods to limit potential model instabilities from feature multicollinearity. Using only preoperative features, mortality prediction achieved an area under the receiver operating characteristic curve (AUC) of 0.53 (95% CI: 0.44–0.78). By using intraoperative features, performance improved significantly to 0.82 (95% CI: 0.56–0.91, P = 0.001). Similarly, including intraoperative features (AUC = 0.82; 95% CI: 0.66–0.94) in ARF prediction improved performance over preoperative features (AUC = 0.72; 95% CI: 0.50–0.85), though not significantly (P = 0.32). We conclude that inclusion of intraoperative hemodynamic features significantly improves prediction of postoperative events in OLT. Features strongly associated with occurrence of both outcomes included greater intraoperative central venous pressure and greater transfusion volumes.

Perioperative fluid volume optimization following proximal femoral fracture

BACKGROUND

Proximal femoral fracture (PFF) is a common orthopaedic emergency that affects mainly elderly people at high risk of complications. Advanced methods for managing fluid therapy during treatment for PFF are available, but their role in reducing risk is unclear.

OBJECTIVES

To compare the safety and effectiveness of the following methods of perioperative fluid optimization in adult participants undergoing surgical repair of hip fracture: advanced invasive haemodynamic monitoring, such as transoesophageal Doppler and pulse contour analysis; a protocol using standard measures, such as blood pressure, urine output and central venous pressure; and usual care.Comparisons of fluid types (e.g. crystalloid vs colloid) and other methods of optimizing oxygen delivery, such as blood product therapies and pharmacological treatment with inotropes and vasoactive drugs, are considered in other reviews.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL; 2015, Issue 9); MEDLINE (October 2012 to September 2015); and EMBASE (October 2012 to September 2015) without language restrictions. We ran forward and backward citation searches on identified trials. We searched ClinicalTrials.gov and the World Health Organization (WHO) International Clinical Trials Registry Platform for unpublished trials. This is an updated version of a review published originally in 2004 and updated first in 2013 and again in 2015. Original searches were performed in October 2003 and October 2012.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) in adult participants undergoing surgical treatment for PFF that compared any two of advanced haemodynamic monitoring, protocols using standard measures or usual care, irrespective of blinding, language or publication status.

DATA COLLECTION AND ANALYSIS

Two review authors assessed the impact of fluid optimization interventions on outcomes of mortality, length of hospital stay, time to medical fitness, whether participants were able to return to pre-fracture accommodation at six months, participant mobility at six months and adverse events in-hospital. We pooled data using risk ratio (RR) or mean difference (MD) for dichotomous or continuous data, respectively, on the basis of random-effects models.

MAIN RESULTS

We included in this updated review five RCTs with a total of 403 participants, and we added two new trials identified during the 2015 search. One of the included studies was found to have a high risk of bias; no trial featured all pre-specified outcomes. We found two trials for which data are awaited for classification and one ongoing trial.Three studies compared advanced haemodynamic monitoring with a protocol using standard measures; three compared advanced haemodynamic monitoring with usual care; and one compared a protocol using standard measures with usual care. Meta-analyses for the two advanced haemodynamic monitoring comparisons are consistent with both increased and decreased risk of mortality (RR Mantel-Haenszel (M-H) random-effects 0.41, 95% confidence interval (CI) 0.14 to 1.20; 280 participants; RR M-H random-effects 0.45, 95% CI 0.07 to 2.95; 213 participants, respectively). The study comparing a protocol with usual care found no difference between groups for this outcome.Three studies comparing advanced haemodynamic monitoring with usual care reported data for length of stay and time to medical fitness. There was no statistically significant difference between groups for these outcomes in the two studies that we were able to combine (MD IV fixed 0.63, 95% CI -1.70 to 2.96); MD IV fixed 0.01, 95% CI -1.74 to 1.71, respectively) and no statistically significant difference in the third study. One study reported reduced time to medical fitness when comparing advanced haemodynamic monitoring with a protocol, and when comparing protocol monitoring with usual care.The number of participants with one or more complications showed no statistically significant differences in each of the two advanced haemodynamic monitoring comparisons (RR M-H random-effects 0.83, 95% CI 0.59 to 1.17; 280 participants; RR M-H random-effects 0.72, 95% CI 0.40 to 1.31; 173 participants, respectively), nor any differences in the protocol and usual care comparison.Only one study reported the number of participants able to return to normal accommodation after discharge with no statistically significant difference between groups.There were few studies with a small number of participants, and by using the GRADE (Grades of Recommendation, Assessment, Development and Evaluation Working Group) approach, we judged the quality of the outcome evidence as low. We had included one study with a high risk of bias, but upon applying GRADE, we downgraded the quality of this outcome evidence to very low.

AUTHORS' CONCLUSIONS

Five studies including a total of 403 participants provided no evidence that fluid optimization strategies improve outcomes for participants undergoing surgery for PFF. Further research powered to test some of these outcomes is ongoing.

Management of post-operative fistula in head and neck surgery: Sweeping it under the carpet?

The most dreaded complication in head and neck surgery is the development of fistula. Fistulas are common and devastating. The prevalence and the risk factors that contribute to fistula formation after head and neck procedures were discussed briefly. The main goal of this manuscript is to discuss current management of head and neck fistula. We believed that the best management strategy for head and neck fistulas is prevention. We recommend a holistic preventive approach during the perioperative period. The roles of different types of wound products and hyperbaric oxygen therapy were also discussed and highlighted. We also discussed the operative repair of fistulas, which relies on the tenet of providing well-vascularized tissue to an area of poor wound healing. Most often, the surgeon’s preference and range of operative skills dictate the timing and the type of repair. We highlighted the use of the pectoralis major, a well-known flap, as well as a novel technique in the surgical repair of complex, difficult-to-heal head and neck fistula.

Feeding duodenostomy decreases the incidence of mechanical obstruction after radical esophageal cancer surgery

BACKGROUND

Nutritional support influences the outcome of gastroenterological surgery, and enteral nutrition effectively mitigates postoperative complications in highly invasive surgery such as resection of esophageal cancer. However, feeding via jejunostomy can cause complications including mechanical obstruction, which could be life threatening. From 2009, we began enteral feeding via duodenostomy to reduce the likelihood of complications. In this study, we compared duodenostomy with the conventional jejunostomy feeding, mainly looking at the catheter-related complications.

METHODS

The database records of 378 patients with esophageal cancer who underwent radical esophagectomy with retrosternal or posterior mediastinal gastric tube reconstruction in our department from January 1998 to December 2012 were examined. Of the 378 patients, 111 underwent feeding via duodenostomy (FD) and 267 underwent feeding via jejunostomy (FJ), and their records were reviewed for the following catheter-related complications: site infection, dislodgement, peritonitis, and mechanical obstruction.

RESULTS

Mechanical obstruction occurred in 12 patients in the FJ group but none in the FD group (4.5 % vs. 0 %, P = 0.023). Of the 12 cases, 7 (58.3 %) required surgery of which 2 had bowel resection due to strangulated mechanical obstruction. Catheter site infection was seen in 14 cases in the FJ group, of which 2 (14.2 %) had peritonitis following catheter dislocation, while only one case of site infection was seen in the FD group (5.2 % vs. 0.9 %, P = 0.078).

CONCLUSIONS

Feeding via duodenectomy could be the procedure of choice since neither mechanical obstruction nor relaparotomy was seen during enteral feeding through this technique.

Clarification of the circulatory patho-physiology of anaesthesia - implications for high-risk surgical patients

The paper examines the effects of anaesthesia on circulatory physiology and their implications regarding improvement in perioperative anaesthetic management. Changes to current anaesthetic practice, recommended recently, such as the use of flow monitoring in high risk patients, are already beginning to have an impact in reducing complications but not mortality [1]. Better understanding of the patho-physiology should help improve management even further. Analysis of selected individual clinical trials has been used to illustrate particular areas of patho-physiology and how changes in practice have improved outcome. There is physiological support for the importance of achieving an appropriate rate of oxygen delivery (DO2), particularly following induction of anaesthesia. It is suggested that ensuring adequate DO2 during anaesthesia will avoid development of oxygen debt and hence obviate the need to induce a high, compensatory, DO2 in the post-operative period. In contrast to the usual assumptions underlying strategies requiring a global increase in blood flow [1] by a stroke volume near maximization strategy, blood flow control actually resides entirely at the tissues not at the heart. This is important as the starting point for understanding failed circulatory control as indicated by 'volume dependency'. Local adjustments in blood flow at each individual organ - auto-regulation - normally ensure the appropriate local rate of oxygen supply, i.e. local DO2. Inadequate blood volume leads to impairment of the regulation of blood flow, particularly in the individual tissues with least capable auto-regulatory capability. As demonstrated by many studies, inadequate blood flow first occurs in the gut, brain and kidney. The inadequate blood volume which occurs with induction of anaesthesia is not due to blood volume loss, but probably results from redistribution due to veno-dilation. The increase in venous capacity renders the existing blood volume inadequate to maintain venous return and pre-load. Blood volume shifted to the veins will, necessarily, also reduce the arterial volume. As a result stroke volume and cardiac output fall below normal with little or no change in peripheral resistance. The resulting pre-load dependency is often successfully treated with colloid infusion and, in some studies, 'inotropic' agents, particularly in the immediate post-operative phase. Treatment during the earliest stage of anaesthesia can avoid the build up of oxygen debt and may be supplemented by drugs which maintain or restore venous tone, such as phenylephrine; an alternative to volume expansion. Interpretation of circulatory patho-physiology during anaesthesia confirms the need to sustain appropriate oxygen delivery. It also supports reduction or even elimination of supplementary crystalloid maintenance infusion, supposedly to replace the "mythical" third space loss. As a rational evidence base for future research it should allow for further improvements in anaesthetic management.

Anesthesia, microcirculation, and wound repair in aging

Age-related changes in skin contribute to impaired wound healing after surgical procedures. Changes in skin with age include decline in thickness and composition, a decrease in the number of most cell types, and diminished microcirculation. The microcirculation provides tissue perfusion, fluid homeostasis, and delivery of oxygen and other nutrients. It also controls temperature and the inflammatory response. Surgical incisions cause further disruption of the microvasculature of aged skin. Perioperative management can be modified to minimize insults to aged tissues. Judicious use of fluids, maintenance of normal body temperature, pain control, and increased tissue oxygen tension are examples of adjustable variables that support the microcirculation. Anesthetic agents influence the microcirculation of a combination of effects on cardiac output, arterial pressure, and local microvascular changes. The authors examined the role of anesthetic management in optimizing the microcirculation and potentially improving postoperative wound repair in older persons.

Multimodal intraoperative monitoring: an observational case series in high risk patients undergoing major peripheral vascular surgery

Recent guidelines from the National Institute of Health and Care Excellence (NICE) and the UK National Health Service (NHS) have stipulated that intraoperative flow monitoring should be used in high-risk patients undergoing major surgery to improve outcomes and reduce costs. Depth of anaesthesia monitoring is also recommended for patients where excessive anaesthetic depth is poorly tolerated, along with cerebral oximetry in patients with proximal femoral fractures. The aims of this descriptive case series were to evaluate the impact of a multimodal intraoperative strategy and its effect on mortality and amputation rate for patients with critical leg ischaemia. In an observational case series, 120 elderly patients undergoing major infra-inguinal bypass between 2007 and 2012 were included in this retrospective analysis of prospectively collected data. Nominal cardiac output (nCO, LiDCOrapid, LiDCO Ltd, UK), bispectral index to monitor depth of anaesthesia (BIS, Covidien, USA) and cerebral oxygenation, rSO2 (Invos, Covidien, USA) readings were obtained before induction of general anaesthesia and throughout surgery. 30 day, 1-year mortality and amputation rates were analysed. Demographics and physiological parameters including correlation with V-POSSUM, age, gender and other co-morbidities were statistically analysed. Thirty-day mortality rate was 0.8% (n = 1). V-POSSUM scoring indicated a predicted mortality of 9%. Amputation rate was less than 2% at one year. Only 8% of patients (10 of 120) were admitted to a high dependency unit (HDU) postoperatively. 30-day mortality in our case series was lower than predicted by V-POSSUM scoring. Use of multimodal intraoperative monitoring with the specific aim of limiting build-up of oxygen debt should be subjected to a randomised controlled study to assess the reproducibility of these results.

Perioperative fluid volume optimization following proximal femoral fracture

BACKGROUND

Proximal femoral fracture (PFF) is a common orthopaedic emergency, affecting mainly elderly people at high risk of complications. Advanced methods for managing fluid therapy during treatment for PFF are available, but their role in reducing risk is unclear.

OBJECTIVES

To compare the safety and effectiveness of different methods of perioperative fluid optimization in adult participants undergoing surgical repair of hip fracture. We considered the following methods: advanced invasive haemodynamic monitoring, such as transoesophageal Doppler and pulse contour analysis; a protocol using standard measures, such as blood pressure, urine output and central venous pressure; and usual care.Comparisons of fluid types (e.g. crystalloid vs colloid) and other methods of optimizing oxygen delivery, such as blood product therapies and pharmacological treatment with inotropes and vasoactive drugs, are considered elsewhere.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2012, Issue 9); MEDLINE (1966 to October 2012); and EMBASE (1980 to October 2012) without language restrictions. We ran forward and backward citation searches on identified trials. We contacted authors and searched ClinicalTrials.gov and the WHO International Clinical Trials Registry Platform for unpublished trials. This is an updated version of a review published in 2004. The original search was performed in October 2003.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) in adult participants undergoing surgical treatment for PFF, which compared any two of advanced haemodynamic monitoring, protocols using standard measures or usual care, irrespective of blinding, language or publication status.

DATA COLLECTION AND ANALYSIS

Two review authors assessed the impact of fluid optimization interventions on outcomes of mortality, length of hospital stay, return of participant to pre-fracture accommodation and mobility at six months and adverse events in hospital. We pooled data using risk ratio or mean difference for dichotomous or continuous data, respectively, based on random-effects models.

MAIN RESULTS

We included three RCTs with a total of 200 participants. One of these included studies was found to have a high risk of bias; no trial featured all pre-specified outcomes. We found one trial for which data are awaited for classification and two ongoing trials. One included study with low risk of bias found that compared with usual care, time to medical fitness for discharge was shorter with the use of advanced haemodynamic monitoring (mean reduction 6.20 days, 95% CI 2.3 to 10.1 days; 59 participants, one trial) and with the use of protocols that apply standard measures (mean reduction 3.9 days, 95% CI 0.75 to 7.05; 57 participants, one trial). Our results are consistent with both increased and decreased risk of mortality and adverse events in participants receiving the intervention. No data for other outcomes were available. Our results are limited by the quantity of available data.

AUTHORS' CONCLUSIONS

Three studies considering a total of 200 participants reveal an absence of evidence that fluid optimization strategies improve outcomes for participants undergoing surgery for PFF. Length of hospital stay may be improved, but lack of good quality data leaves uncertainty. Further research powered to test some of these outcomes is ongoing.

Analysis of neuron-specific enolase and S100B as biomarkers of cognitive decline following surgery in older people

BACKGROUND/AIMS

Post-operative cognitive decline is frequent in older individuals following major surgery; however, biomarkers of this decline are less clearly defined.

METHODS

Sixty-eight participants over the age of 60 provided blood samples at baseline and 24 h post-surgery. Cognitive decline was measured at baseline and 52 weeks post-surgery using the Cambridge Assessment for Mental Disorder in the Elderly, section B (CAMCOG) score. Plasma levels of neuron-specific enolase (NSE) and S100B were measured by ELISA.

RESULTS

Baseline NSE and the change in NSE levels between baseline and 24 h were correlated with the change in CAMCOG score between baseline and 52 weeks.

CONCLUSION

NSE concentrations may be a useful predictor of individuals at risk of more severe long-term cognitive decline.

Using bispectral index and cerebral oximetry to guide hemodynamic therapy in high-risk surgical patients

High-risk surgery represents 12.5% of cases but contributes 80% of deaths in the elderly population. Reduction in morbidity and mortality by the use of intervention strategies could result in thousands of lives being saved and savings of up to £400m per annum in the UK. This has resulted in the drive towards goal-directed therapy and intraoperative flow optimization of high-risk surgical patients being advocated by authorities such as the National Institute of Health and Care Excellence and the Association of Anaesthetists of Great Britain and Ireland.Conventional intraoperative monitoring gives little insight into the profound physiological changes occurring as a result of anesthesia and surgery. The build-up of an oxygen debt is associated with a poor outcome and strategies have been developed in the postoperative period to improve outcomes by repayment of this debt. New monitoring technologies such as minimally invasive cardiac output, depth of anesthesia and cerebral oximetry can minimize oxygen debt build-up. This has the potential to reduce complications and lessen the need for postoperative optimization in high-dependency areas.Flow monitoring has thus emerged as essential during intraoperative monitoring in high-risk surgery. However, evidence suggests that current optimization strategies of deliberately increasing flow to meet predefined targets may not reduce mortality.Could the addition of depth of anesthesia and cerebral and tissue oximetry monitoring produce a further improvement in outcomes?Retrospective studies indicate a combination of excessive depth of anesthesia hypotension and low anesthesia requirement results in increased mortality and length of hospital stay.Near infrared technology allows assessment and maintenance of cerebral and tissue oxygenation, a strategy, which has been associated with improved outcomes. The suggestion that the brain is an index organ for tissue oxygenation, especially in the elderly, indicates a role for this technology in the intraoperative period to assess the adequacy of oxygen delivery and reduce the build-up of an oxygen debt.The aim of this article is to make the case for depth of anesthesia and cerebral oximetry alongside flow monitoring as a strategy for reducing oxygen debt during high-risk surgery and further improve outcomes in high-risk surgical patients.

Intra- and inter-beat modeling of cardiovascular dynamics and control: assessing haemodynamic stability and responsiveness

In critical care patient management, extensive and invasive patient monitoring is routinely performed in order to quantify patient status in view of therapeutic interventions. Little quantitative integration is performed when collecting information from multiple monitors, and processing algorithms are often based on little physiological understanding. Mechanistic modeling can offer insight into the mechanisms underlying patient stability and sensitivity to alterations in physiological variables. Starting from existing models, we construct an integrated model which combines detailed neural cardiovascular regulation with realistic circulation modeling, using Monte-Carlo techniques for reparameterisation when merging the two models. The combined model is analyzed in terms of its dynamical stability and sensitivity to parameter perturbations under simulated conditions of fluid deficit, anaesthesia, and dilatative cardiomyopathy. The results exemplify how a structural model can serve as a quantitative guide in assessing how different underlying patient states can alter the haemodynamics impact of external therapeutic intervention.

Cardiac output monitoring to guide fluid replacement in head and neck microvascular free flap surgery-what is current practice in the UK?

Appropriate fluid balance is an important factor in the survival of free flaps, and recently there has been a shift towards more conservative fluid regimens. Several surgical specialties have made extensive use of the relatively non-invasive method of measuring cardiac output (CO) to optimise fluid balance during and after surgery, which has resulted in a shorter hospital stay, but little has been published in head and neck surgery. To ascertain its use in the head and neck we sent a postal questionnaire to the anaesthetic departments of 40 major head and neck units identified from the 2010 database of the British Association of Oral and Maxillofacial Surgeons (BAOMS). Questions were asked about the number of free flaps done in the unit each year, the monitoring of central venous and arterial blood pressure (and inotrope protocols), optimal target variables, and whether CO was monitored (with type of device). Thirty-two units responded (80%). While 26 units (81%) routinely monitored central venous pressure (CVP), CO was monitored in only 3 units (9%). There was a wide range of responses in relation to optimal variables and use of inotropes. As with other specialties, it is likely that CO monitoring will become widely used in head and neck reconstructive surgery. Not only does it enhance fluid optimisation, but it may also reduce hospital stay and morbidity. Appropriate clinical studies are urgently needed to evaluate its use in our specialty.

Postoperative atrial fibrillation

Postoperative atrial fibrillation (POAF) is common among surgical patients and associated with a worse outcome. Pathophysiology of POAF is not fully disclosed, and several perioperative factors could be involved. Direct cardiac stimulation from perioperative use of catecholamines or increased sympathetic outflow from volume loss/anaemia/pain may play a role. Metabolic alterations, such as hypo-/hyperglycaemia and electrolyte disturbances, may also contribute to POAF. Moreover, inflammation, both systemic and local, may play a role in its pathogenesis. Strategies to prevent POAF aim at reducing its incidence and ameliorate global outcome of surgical patients. Nonpharmacological prophylaxis includes an adequate control of postoperative pain, the use of thoracic epidural analgesia, optimization of perioperative oxygen delivery, and, possibly, modulation of surgery-associated inflammatory response with immunonutrition and antioxidants. Perioperative potassium and magnesium depletion should be corrected. The impact of those interventions on patients outcome needs to be further investigated.

Shaping the operating room and perioperative systems of the future: innovating for improved competitiveness

PURPOSE OF REVIEW

To review the current state of anesthesiology for operative and invasive procedures, with an eye toward possible future states.

RECENT FINDINGS

Anesthesiology is at once a mature specialty and in a crisis--requiring breakthrough to move forward. The cost of care now approaches reimbursement, and outcomes as commonly measured approach perfection. Thus, the cost of further improvements seems ready to topple the field, just as the specialty is realizing that seemingly innocuous anesthetic choices have long-term consequences, and better practice is required.

SUMMARY

Anesthesiologists must create more headroom between costs and revenues in order to sustain the academic vigor and creativity required to create better clinical practice. We outline three areas in which technological and organizational innovation in anesthesiology can improve competitiveness and become a driving force in collaborative efforts to develop the operating rooms and perioperative systems of the future: increasing the profitability of operating rooms; increasing the efficiency of anesthesia; and technological and organizational innovation to foster improved patient flow, communication, coordination, and organizational learning.