Reconstruction of the phreno-esophageal ligament (R-PEL) prevents the intrathoracic migration (ITM) after concomitant sleeve gastrectomy and hiatal hernia repair.

BACKGROUND: Laparoscopic Sleeve Gastrectomy (LSG) is the most attractive bariatric procedure, but the postoperative intrathoracic gastric migration (ITM) and "de novo" GERD are major concerns. The main objective of our study was to evaluate the efficiency of the concomitant HHR with or without partial reconstruction of phreno-esophageal ligament (R-PEL) to prevent ITM after LSG. The secondary objectives focused on procedure's metabolic and GERD-related outcomes. PATIENTS AND METHOD: Consecutive patients who underwent primary LSG and concomitant HHR were included in a single-center prospective study. According to the HHR surgical technique, two groups were analyzed and compared: Group A included patients receiving crura approximation only and Group B patients with R-PEL. The patients' evolution of co-morbidities, GERD symptoms, radiologic, and endoscopic details were prospectively analyzed. RESULTS: Two hundred seventy-three patients undergoing concurrent HHR and LSG were included in the study (Group A and B, 146 and 127 patients) The mean age and BMI were 42.6 ± 11.3 and 43.4 ± 6.8 kg/m2. The 12-month postoperative ITM was radiologically found in more than half of the patients in Group A, while in group B, the GEJ's position appeared normal in 91.3% of the patients, meaning that R-PEL reduced 7 times the rate of ITM. The percentage of no-improvement and "de novo" severe esophagitis (Los Angeles C) was 4 times higher in group A 3.4% vs. 0.8% with statistical significance, and correlated to ITM. The GERD symptoms were less frequent in Group B vs Group A, 21.3% vs 37%, with statistical significance. No Barrett's esophagus and no complication were recorded in any of the patients. CONCLUSION: Concurrent LSG and HHR by crura approximation only has a very high rate of ITM in the first postoperative year (over 50%). R-PEL is an innovative technique which proved to be very efficient in preventing the ITM after HHR.

Regional differences of hemodynamics and oxygenation in the human calf muscle detected with near-infrared spectrophotometry.

PURPOSE: Measurements in muscle tissue are often performed at a selected single location over the muscle of interest. The hypothesis is that the values obtained reflect the status within the entire muscle or muscle group. This, however, may not be the case. The study was performed to investigate whether this hypothesis is true for hemodynamics and oxygenation in the healthy human calf muscle at rest. MATERIALS AND METHODS: Hemoglobin flow, blood flow, oxygen consumption, and venous hemoglobin oxygen saturation were mapped at 22 locations in 30 legs of 15 healthy subjects (nine women, six men aged 26-37 years) simultaneously by using frequency-domain near-infrared spectrophotometry with a specially designed probe during venous occlusion. RESULTS: For all parameters, spatial heterogeneity was found between subjects and within individual legs. All parameters were highly significantly different when comparing proximal and distal regions. Differences were also found between medial and lateral regions. The global mean values (+/-standard deviation) over all measurements were as follows: hemoglobin flow, 1.27 micromol per 100 mL/min +/- 0.88; blood flow, 0.56 mL per 100 g/min +/- 0.38; oxygen consumption, 0.016 mL per 100 g/min +/- 0.011; and venous oxygen saturation, 77.6% +/- 5.9. The thickness of the overlying adipose tissue had an influence on the measurements and must be considered. CONCLUSION: Highly significant spatial heterogeneity of hemodynamics and oxygenation was found in the healthy human calf muscle.

Retinal nerve fiber layer assessment using optical coherence tomography with active optic nerve head tracking.

PURPOSE: To develop an eye-motion-tracking optical coherence tomographic (OCT) method and assess its effect on image registration and nerve fiber layer (NFL) thickness measurement reproducibility. METHODS: A system capable of tracking common fundus features based on reflectance changes was integrated into a commercial OCT unit (OCT II; Carl Zeiss Meditec, Inc., Dublin, CA) and tested on healthy subjects and patients with glaucoma. Twenty successive peripapillary NFL scans were obtained with tracking and 20 without tracking, for 40 images in each session for each eye. Subjects participated in one session on three different days. Composite OCT scans and composite fundus images were generated for assessment of eye tracking. NFL thickness measurement reproducibility was also assessed. RESULTS: Seven healthy and nine glaucomatous eyes of 16 subjects were recruited. A qualitative assessment of composite OCT scans and composite fundus images showed little motion artifact or blurring along edges and blood vessels during tracking; however, those structures were less clearly defined when tracking was disengaged. There was no significant reproducibility difference with and without tracking in both intra- and intersession NFL measurement SD calculations in any location. The mean retinal pixel SD was significantly smaller with tracking than without (490.9 +/- 19.3 microm vs. 506.4 +/- 31.8 microm, P = 0.005, paired t-test). CONCLUSIONS: A retinal-tracking system was successfully developed and integrated into a commercial OCT unit. Tracking OCT improved the consistency of scan registration, but did not influence NFL thickness measurement reproducibility in this small sample study.

Fast cerebral functional signal in the 100-ms range detected in the visual cortex by frequency-domain near-infrared spectrophotometry.

Brain activity is associated with physiological changes, which alter the optical properties of the tissue in the near-infrared part of the spectrum. Two major types of optical signals following functional brain activation can be distinguished: a slow signal due to hemodynamic changes and a fast signal, which is directly related to neuronal activity. The fast signal is small and therefore difficult to detect. We used a specially noise-optimized frequency-domain near-infrared spectrometer with a pi-sensor, which was expected to be particularly sensitive to deeper tissue layers, to investigate the human visual cortex during visual stimulation generated by a checkerboard. We were able to detect significant fast signals in single light bundles, but not in pi-signals. The fast signals were mostly collocated with strong slow hemodynamic signals, but showed a higher degree of localization than the latter. The latencies of 40 +/- 16 ms of the fast signals were similar between locations. Our results also indicate that the brain responds differently to a single and double (forth and back) reversal of the checkerboard, with a stronger reaction upon the double reversal.

Localized irregularities in hemoglobin flow and oxygenation in calf muscle in patients with peripheral vascular disease detected with near-infrared spectrophotometry.

PURPOSE: Near-infrared spectrophotometry is used to measure flow, concentration, and oxygenation of hemoglobin in arterioles, capillaries, and venules several centimeters deep in tissue. The purpose of this study was to investigate the distribution of flow, concentration, and oxygenation of hemoglobin in calf muscle in patients with documented peripheral arterial occlusive disease (PVD), patients with risk factors for PVD,and healthy younger subjects at rest. METHOD: With a frequency-domain near-infrared spectrophotometer and a specially designed probe, we generated maps at 22 locations simultaneously of hemoglobin flow, concentration, and oxygenation, with the venous occlusion method. Eight legs of 7 patients with diagnosed PVD (PVD group), 10 legs of 8 patients with normal ankle-brachial index but with risk factors for PVD (RF group), and 16 legs of 8 healthy subjects (H group) were studied. RESULTS: Global mean values were significantly (P <.05) different between the three groups for oxygen consumption (PVD group, 0.027 +/- 0.009 mL/100 g/min; RF group, 0.038 +/- 0.017 mL/100 g/min; H group, 0.022 +/- 0.020 mL/100 g/min), venous oxygen saturation (PVD, 59.7% +/- 15.4%; RF, 69.6% +/- 10.5%; H, 80.8% +/- 4.5%), and, at 60 s of venous occlusion, concentration changes in oxyhemoglobin (PVD, 4.48 +/- 3.25 micromol/L; RF, 8.44 +/- 2.33 micromol/L; H, 6.85 +/- 4.57 micromol/L), deoxyhemoglobin (PVD, 3.60 +/- 0.73 micromol/L; RF, 4.39 +/- 1.30 micromol/L; H, 2.36 +/- 1.79 micromol/L), and total hemoglobin (PVD, 8.07 +/- 3.83 micromol/L; RF, 12.83 +/- 2.75 micromol/L; H, 9.21 +/- 6.34 micromol/L). No significant difference was found between the three groups for hemoglobin flow (PVD, 0.92 +/- 0.69 micromol/100 mL/min; RF, 1.68 +/- 0.50 micromol/100 mL/min; H, 1.44 +/- 1.17 micromol/100 mL/min) and blood flow (PVD, 0.45 +/- 0.28 mL/100 g/min; RF, 0.77 +/- 0.21 mL/100 g/min; H, 0.62 +/- 0.50 mL/100 g/min). All parameters featured a distribution dependent on location. CONCLUSION: Mean value for venous oxygen saturation was higher in healthy subjects compared to patients with documented PVD. In patients with PVD, areas of lower oxygenation were clearly discernible. At distal locations of calf muscle, significant correlations between reduced hemoglobin flow, venous oxygen saturation, oxyhemoglobin, and total hemoglobin and reduced ankle-brachial index were found. Maps revealed localized irregularities in oxyhemoglobin, total hemoglobin, and venous oxygen saturation in patients with PVD. Near-infrared spectrophotometry is a noninvasive bedside technique that can enable determination of blood flow and oxygenation in tissue and may provide a method for evaluating patients with PVD.

Detection of the fast neuronal signal on the motor cortex using functional frequency domain near infrared spectroscopy.

Using non-invasive near infrared spectroscopy fast changes in the range of ms in the optical properties of neurons during brain activity have been described. Since the signal is small, the system to detect it has to be highly noise optimized. We used a frequency-domain tissue oximeter, whose laser diodes were modulated at 110 MHz and the amplitude (AC), mean intensity (DC) and phase (phi) of the modulated optical signal was measured at 96 Hz sample rate. In two volunteers, 36 and 37 years old, the probe consisting of 4 crossed source detector pairs was placed above the motor cortex (C3 position), contralateral to the hand performing the tapping exercise. The tapping frequency was set at 2.5 times the heart rate of the subject to avoid the influence of harmonics on the signal. An electronic device recorded the tapping movement. Control-data were obtained from a solid medium of approximately the same optical properties as the human head. To reduce physiological noise the arterial pulsatility was removed using an adaptive filter, the data was detrended by a high pass filter and a cross correlation function between the optical data and the tapping signal was calculated. The instrumental noise of the control data was very low (AC mean 0.0015% +/- SD 0.00092%, DC 0.00037% +/- 0.00023% and phi 0.00083 degrees +/- 0.00042 degrees). On the head the noise level was AC 0.0042% +/- 0.0031%, DC 0.0021% +/- 0.0012% and phi 0.0020 degrees +/- 0.0017 degrees. In 14 DC, 5 AC and 0 phi out of 30 locations a fast signal was detected, which was higher (p<0.001) than the noise level. This signal disappeared during non-tapping periods. With the signal to noise ratio that we have achieved single subject measurements become feasible.

Mapping of hemodynamics on the human calf with near infrared spectroscopy and the influence of the adipose tissue thickness.

We investigated the influence of the adipose tissue thickness (ATT) on near-infrared spectroscopy (NIRS) measurements of the absorption coefficient (mu a), the reduced scattering coefficient (mu s') and changes in concentrations of oxyhemoglobin ([O2Hb]) and deoxyhemoglobin ([HHb]). We used a frequency domain spectrometer and a special probe to generate maps of these parameters on the human calf during venous occlusion. For ATT below 6 mm mu a remained constant, whereas for ATT between 6 and 14 mm mu a decreased quickly and became almost constant again for ATT larger than 14 mm. Mu s' was not significantly altered by the ATT but the values showed a high variability between subjects. We found significantly different changes in both the [O2Hb] and the [HHb] between the proximal and distal locations of measurement. Although ATT influences the recovery of the optical properties of the underlying tissue, these differences depending on the location cannot be sufficiently explained by the ATT for the following reasons. The ATT varied little within one subject (mean difference 0.88 +/- 1.80 mm). The inter-subject variability was 5 times higher. For a given ATT within one subject we observed different values for changes in [O2Hb] and [HHb] depending on the measurement location. Moreover for a smaller ATT the difference between the values of delta[O2Hb] and delta[HHb] proximal versus distal were more distinct. The thinner the overlying tissue (ATT) the higher is the proportion of muscle tissue in the probed tissue volume. Therefore these differences are most likely coming from the muscle tissue rather than the ATT. This indicates that although the ATT has an evident influence on the measurement of optical parameters and hemodynamics and should therefore be recognized when performing NIRS measurements, other factors will have to be considered as well.

Functional frequency-domain near-infrared spectroscopy detects fast neuronal signal in the motor cortex.

Millisecond changes in the optical properties of the human brain during stimulation were detected in five volunteers using noninvasive frequency-domain near-infrared spectroscopy. During a motor stimulation task we found highly significant signals, which were directly related to neuronal activity and exhibited much more localized patterns than the slow hemodynamic signals that are also detected by the near-infrared method. We considerably reduced the noise in the instrumental system and improved data analysis algorithms. With the achieved signal-to-noise ratio, single subject measurements were feasible without the requirement of particularly strong stimuli and within a reasonable period of measurement of 5 min at a mean signal-to-noise ratio of 3.6. The advantage of this noninvasive technique with respect to electrical recording is that it is able to detect neuronal activity with the relatively high spatial resolution of 8 mm.

Different time evolution of oxyhemoglobin and deoxyhemoglobin concentration changes in the visual and motor cortices during functional stimulation: a near-infrared spectroscopy study.

Neurovascular coupling is the generic term for changes in cerebral metabolic rate of oxygen (CMRO(2)), cerebral blood flow, and cerebral blood volume related to brain activity. The goal of this paper is to better understand the effects of neurovascular coupling in the visual and motor cortices using frequency-domain near-infrared spectroscopy. Maps of concentration changes in oxyhemoglobin [O(2)Hb], deoxyhemoglobin [HHb], and total hemoglobin of the visual and motor cortices were generated during stimulation using a reversing checkerboard screen and palm-squeezing, respectively. Seven healthy volunteers of 18-37 years of age were included. In the visual cortex the patterns of [O(2)Hb] and [HHb] were strongly linearly correlated (r(2) > 0.8 in 13 of a total of 24 locations). In 20 locations the change in [O(2)Hb] was larger than 0.25 microM. The mean slope of the linear regression between [O(2)Hb] and [HHb] was -3.93 +/- 0.31 (SE). The patterns of the [O(2)Hb] and [HHb] traces over the motor cortex looked different. The [O(2)Hb] reached its maximum change a few seconds before the [HHb] reached its minimum. This was confirmed by the linear regression analysis (r(2) > 0.8 in none of 40 locations). In 20 locations the change in [O(2)Hb] was larger than 0.25 microM. The mean slope of the regression line was -1.76 +/- 0.20, which is significantly higher than that in the motor cortex (P < 0.0000001). Patterns of [O(2)Hb] and [HHb] differ among cortex areas. This implies that the regulation of perfusion in the visual cortex is different from that in the motor cortex. There is evidence that the CMRO(2) increases substantially in the visual cortex, while this is not the case for the motor cortex.

Blood flow and oxygen consumption with near-infrared spectroscopy and venous occlusion: spatial maps and the effect of time and pressure of inflation.

We have measured the local blood flow (BF) and oxygen consumption (OC) in the human calf muscle using near-infrared spectroscopy during venous occlusion. Venous occlusion was achieved by inflating a pneumatic cuff around the thigh of the subject. We have investigated the influence of the inflation time and cuff pressure on the recovered values of BF and OC. We have found that if the cuff pressure is increased from a threshold pressure (approximately 30 mm Hg) to a critical pressure (approximately 45 mm Hg) in less than about 6 s, one measures the same values of BF and OC independent of the total inflation time and final cuff pressure. We also report nine-pixel spatial maps of BF and OC to show that this technique can lead to spatially resolved measurements of blood flow and oxygen consumption in tissues.

Application of near-infrared tissue oxymetry to the diagnosis of peripheral vascular disease.

Near-infrared spectroscopy (NIRS) is a noninvasive technique to measure the tissue oxygenation in real time. This optical method has many advantages over the invasive analysis currently used for clinical tests. Among the possible applications of near-infrared oxymetry, we report three protocols (exercise, venous occlusion and tilting table) in conjunction with NIRS, and discuss their applicability in the diagnosis of peripheral vascular disease (PVD).

Influence of a superficial layer in the quantitative spectroscopic study of strongly scattering media.

We have experimentally investigated the meaning of the effective optical absorption [mu(a)((eff))] and the reduced scattering [mu(s)?((eff))] coefficients measured on the surfaces of two-layered turbid media, using the diffusion equation for homogeneous, semi-infinite media. We performed frequency-domain spectroscopy in a reflectance geometry, using source-detector distances in the range 1.5-4.5 cm. We measured 100 samples, each made of one layer (thickness in the range 0.08-1.6 cm) on top of one semi-infinite block. The optical properties of the samples were similar to those of soft tissues in the near infrared. We found that the measured effective optical coefficients are representative of the underlying block if the superficial layer is less than ~0.4 cm thick, whereas they are representative of the superficial layer if it is more than ~1.3 cm thick.