Power spectral analysis of the effects of epinephrine,norepinephrine, dobutamine and dopexamine on microcirculation following free tissue transfer

Background: The use of pressor drugs after microsurgical free tissue transfer remains controversial because of potential vasoconstrictor effects on the free flap. Noninvasive monitoring of free flaps with laser Doppler flowmetry may provide further information regarding the local regulation of blood flow in the flap tissues during pressor infusions. This study evaluated the effects of four commonly used pressor agents. Methods: Twenty four patients (25 data sets) undergoing head and neck cancer resection and free flap reconstruction were recruited. Epinephrine, norepinephrine, dopexamine, and dobutamine were infused in a random order at four infusion rates, after surgery, with free flap and control area (deltoid region) laser Doppler skin blood flow monitoring. Frequency analysis of the Doppler waveform was performed utilizing the time period immediately before the first drug infusion for each patient as baseline. Results: At baseline there was less power at the 0.002–0.6 Hz frequency in the flap compared with control tissue consistent with surgical denervation. At maximum epinephrine infusion rates, the control of blood flow moved toward (i.e., proportion of power increased in) the lower frequencies, as smooth muscle mediated (myogenic) control began to dominate blood flow, an effect most marked with norepinephrine. Dobutamine and dopexamine had little effect on control of blood flow. Conclusions: Denervation of free flap tissue is demonstrable using spectral analysis of laser Doppler blood flow signals. With norepinephrine the control of blood flow shifts toward low frequency vasomotion where blood flow depends mostly on average blood pressure, making it potentially the most suitable agent following free tissue transfer. © 2013 Wiley Periodicals, Inc. Microsurgery, 2013.     

Major Perioperative Morbidity Does Not Affect Long-Term Survival in Patients Undergoing Esophagectomy for Cancer of the Esophagus or Gastroesophageal Junction

Introduction

The incidence of cancer of the esophagus/GE junction is dramatically increasing but continues to have a dismal prognosis. Esophagectomy provides the best opportunity for long-term cure but is hampered by increased rates of perioperative morbidity. We reviewed our large institutional experience to evaluate the impact of postoperative complications on the long-term survival of patients undergoing resection for curative intent.

Methods

We identified 237 patients who underwent esophagogastrectomy, with curative intent, for cancer between 1994 and 2008. Complications were graded using the previously published Clavien scale. Survival was calculated using Kaplan–Meier methodology and survival curves were compared using log-rank tests. Multivariate analysis was performed with continuous and categorical variables as predictors of survival, and examined with logistic regression and odds ratio confidence intervals.

Results

There were 12 (5 %) perioperative deaths. The average age of all patients was 62 years, and the majority (82 %) was male. Complication grade did not significantly affect long-term survival, although patients with grade IV (serious) complications did have a decreased survival (p = 0.15). Predictors of survival showed that the minimally invasive type esophagectomy (p = 0.0004) and pathologic stage (p = 0.0007) were determining factors. There was a significant difference in overall survival among patients who experienced pneumonia (p = 0.00016) and respiratory complications (p = 0.0004), but this was not significant on multivariate analysis.

Conclusions

In this single-institution series, we found that major perioperative morbidity did not have a negative impact on long-term survival which is different than previous series. The impact of tumor characteristics at time of resection on long-term survival is of most importance.     

Total Hip Arthroplasty in Patients 50 Years or Less : Do We Improve Activity Profiles?

The primary objective of this study was to use step activity monitoring to quantify activity changes after total hip arthroplasty in patients 50 years or less. Secondly, we investigated whether step activity measurements correlated with the Harris hip and UCLA scores. We prospectively analyzed 37 patients (age ≤ 50) treated with primary THA. Patient activity was recorded with a step activity monitor. Harris hip and UCLA scores were analyzed. Total daily stride counts increased by an average of 30.0%. Increases were noted in the percent of daily time spent at high, moderate and low activity. Increases in daily time spent at high activity moderately correlated with the UCLA activity score but did not correlate with the HHS. Both the UCLA score and the HHS did not correlate with mean daily strides. Following THA, patients ≤ 50 years of age increase their activity by taking more daily strides and improve their activity profile by spending more time at higher activity. Improvements in step activity moderately correlate with improvements in UCLA scores.     

The association of red blood cell n‐3 and n‐6 fatty acids with bone mineral density and hip fracture risk in the women's health initiative

Omega‐3 (n‐3) and omega‐6 (n‐6) polyunsaturated fatty acids (PUFA) in red blood cells (RBCs) are an objective indicator of PUFA status and may be related to hip fracture risk. The primary objective of this study was to examine RBC PUFAs as predictors of hip fracture risk in postmenopausal women. A nested case‐control study (n = 400 pairs) was completed within the Women's Health Initiative (WHI) using 201 incident hip fracture cases from the Bone Mineral Density (BMD) cohort, along with 199 additional incident hip fracture cases randomly selected from the WHI Observational Study. Cases were 1:1 matched on age, race, and hormone use with non–hip fracture controls. Stored baseline RBCs were analyzed for fatty acids using gas chromatography. After removing degraded samples, 324 matched pairs were included in statistical analyses. Stratified Cox proportional hazard models were constructed according to case‐control pair status; risk of fracture was estimated for tertiles of RBC PUFA. In adjusted hazard models, lower hip fracture risk was associated with higher RBC α‐linolenic acid (tertile 3 [T3] hazard ratio [HR]: 0.44; 95% confidence interval [CI], 0.23–0.85; p for linear trend 0.0154), eicosapentaenoic acid (T3 HR: 0.46; 95% CI, 0.24–0.87; p for linear trend 0.0181), and total n‐3 PUFAs (T3 HR: 0.55; 95% CI, 0.30–1.01; p for linear trend 0.0492). Conversely, hip fracture nearly doubled with the highest RBC n‐6/n‐3 ratio (T3 HR: 1.96; 95% CI, 1.03–3.70; p for linear trend 0.0399). RBC PUFAs were not associated with BMD. RBC PUFAs were indicative of dietary intake of marine n‐3 PUFAs (Spearman's rho = 0.45, p < 0.0001), total n‐6 PUFAs (rho = 0.17, p < 0.0001) and linoleic acid (rho = 0.09, p < 0.05). These results suggest that higher RBC α‐linolenic acid, as well as eicosapentaenoic acid and total n‐3 PUFAs, may predict lower hip fracture risk. Contrastingly, a higher RBC n‐6/n‐3 ratio may predict higher hip fracture risk in postmenopausal women. © 2013 American Society for Bone and Mineral Research.     

Perioperative risk factors for 30-day mortality after bariatric surgery: is functional status important?

Background

Although the mortality from bariatric surgery is low, perioperative determinants of morbidity and mortality in the bariatric surgery population to date have not been fully defined. This study aimed to evaluate the factors capable of predicting perioperative mortality based on preoperative characteristics with a national patient sample.

Methods

From the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database, all the primary bariatric procedures performed between 2007 and 2009 were identified. Using univariate analysis, factors associated with increased perioperative (30-day) mortality were identified. Logistic regression was used to select correlates of 30-day mortality, which were subsequently integrated into a simplified clinical scoring system based on the number of comorbid risk factors.

Results

The study identified 44,408 patients (79 % women, 21 % men) with a mean age of 45 ± 11 years. The cumulative 30-day perioperative mortality rate was 0.14 %. The majority of the procedures performed included laparoscopic gastric bypass (54 %) followed by laparoscopic gastric banding (33 %) and open gastric bypass (7 %). Independent predictors associated with significantly increased mortality included age >45 years [adjusted odds ratio (AOR), 2.45], male gender (AOR = 1.77), a body mass index (BMI) of 50 kg/m² or higher (AOR, 2.48), open bariatric procedures (AOR, 2.34), diabetes (AOR, 2.88), functional status of total dependency before surgery (AOR, 27.6), prior coronary intervention (AOR, 2.66), dyspnea at preoperative evaluation (AOR, 4.64), more than 10 % unintentional weight loss in 6 months (AOR, 13.5), and bleeding disorder (AOR, 2.63). Ethnicity, hypertension, alcohol abuse, liver disease, and smoking had no significant association with mortality in this study. Risk stratification based on the number of preoperative comorbid factors showed an exponential increase in mortality as follows: 0–1 comorbidities (0.03 %), 2–3 comorbidities (0.16 %), and 4 comorbidities or more (7.4 %).

Conclusion

This model provides a straightforward, precise, and easily applicable tool for identifying bariatric patients at low, intermediate, and high risk for in-hospital mortality. Notably, baseline functional status before surgery is the single most powerful predictor of perioperative survival and should be incorporated into risk stratification models.     

Salient haptic skills trainer: initial validation of a novel simulator for training force-based laparoscopic surgical skills

Background

There is an increasing need for efficient training simulators to teach advanced laparoscopic skills beyond those imparted by a box trainer. In particular, force-based or haptic skills must be addressed in simulators, especially because a large percentage of surgical errors are caused by the over-application of force. In this work, the efficacy of a novel, salient haptic skills simulator is tested as a training tool for force-based laparoscopic skills.

Methods

Thirty novices with no previous laparoscopic experience trained on the simulator using a pre-test–feedback–post-test experiment model. Ten participants were randomly assigned to each of the three salient haptic skills—grasping, probing, and sweeping—on the simulator. Performance was assessed by comparing force performance metrics before and after training on the simulator.

Results

Data analysis indicated that absolute error decreased significantly for all three salient skills after training. Participants also generally decreased applied forces after training, especially at lower force levels. Overall, standard deviations also decreased after training, suggesting that participants improved their variability of applied forces.

Conclusions

The novel, salient haptic skills simulator improved the precision and accuracy of participants when applying forces with the simulator. These results suggest that the simulator may be a viable tool for laparoscopic force skill training. However, further work must be undertaken to establish full validity. Nevertheless, this work presents important results toward addressing simulator-based force-skills training specifically and surgical skills training in general.     

Robotic versus laparoscopic adrenalectomy: a comparative study in a high-volume center

Background

Minimally invasive surgery has become more popular in recent years. The da Vinci^® robot is one of the new technologies the use of which has gained popularity in a host of different specialties. Originally used in cardiac surgery, marked increases in utilization have been seen in urology, gynecology, and thoracic surgery. Use in general surgical procedures has now become more common. The objective benefits of the robot are unclear compared to those of laparoscopy in many procedures. The aim of this study was to assess the benefits and disadvantages of robot-assisted laparoscopic surgery for adrenalectomy in a high-volume center compared to routine laparoscopic techniques.

Methods

We conducted a retrospective study including consecutive patients who underwent minimally invasive adrenalectomy in a tertiary referral center at the University of Alabama Birmingham. Demographic, clinical, histopathological, and surgical variables were recorded. Patients were divided in two groups: laparoscopic adrenalectomy (LA) and robot-assisted adrenalectomy (RA). Groups were compared using the χ² test for categorical variables and Student’s t-test for continuous variables. Significance was considered p < 0.05.

Results

Sixty patients were included, with 30 patients in each group. There were no significant differences between groups with respect to demographic variables except there were more pheochromocytoma patients in the LA group than in the RA group (13/30 vs. 5/30, respectively; p = 0.02). This study demonstrated increased operative time in the robotic group (190 ± 33 min) versus the laparoscopic group (160 ± 41 min) (p = 0.003). There was a trend for less blood loss in RA versus LA (30 ± 5 ml vs. 55 ± 74 ml; p = 0.07). There was no mortality. Morbidity and length of hospital stay were similar for both groups.

Conclusions

Robotic adrenalectomy is as safe and technically feasible as laparoscopic adrenalectomy. Subjective benefits for the surgeon with robot-assisted surgery include three-dimensional operative view, ergonomically comfortable position, and elimination of the surgeon’s tremor. The operating time is significantly longer but patient outcomes are similar to those of the laparoscopic technique.