Intestinal Afferent Nerve Sensitivity is Increased During the Initial Development of Postoperative Ileus in Mice

Introduction  Neuronal reflex inhibition of gastrointestinal motility is a key mechanism in the development of postoperative ileus (POI). The aim of our study was to determine whether intestinal afferent nerve fibers are sensitized during the first hours after surgery contributing to this mechanism. Methods  Under enflurane anesthesia, C57BL/6 mice underwent laparotomy followed by sham treatment or standardized small bowel manipulation to induce POI. After 1, 3, or 9 h, extracellular multi-unit mesenteric afferent nerve recordings were performed in vitro from 2 cm segments of jejunum (subgroups n = 6) superfused with Kreb’s buffer (32°C, gassed with O₂/CO₂ mixture). Segments were cannulated to monitor luminal pressure and intestinal motility. Afferent impulses as response to bradykinin (0.5 μM) and to mechanical ramp distension of the intestinal lumen from 0 to 80 cmH₂O were recorded. Results  At 1 h, amplitudes of intestinal contractions were 0.8 ± 0.2 cmH₂O after induction of POI and 5.0 ± 0.8 cmH₂O in sham controls (mean ± SEM; p < 0.01). A similar difference was observed for segments harvested at 3 and 9 h. Afferent firing to serosal bradykinin was increased at 1, 3, and 9 h in POI segments compared to sham controls (p < 0.05 at 1 h, p < 0.01 at 3 and 9 h). During distension with high pressures, afferent firing rate was increased at 1 and 3 h in segments after induction of POI compared to sham controls. Nine hours postoperatively, contracted and dilated segments were observed during POI that were investigated separately. While afferent firing in dilated segments was increased to 176 ± 16 imp s⁻¹ at 80 cmH₂O luminal distension (p < 0.01), it was 46 ± 5 imp s⁻¹ in contracted segments (p < 0.001) compared to 77 ± 4 imp s⁻¹ in sham controls. Conclusions  Afferent firing to bradykinin and high threshold distension is augmented in the early phase of POI. As these stimuli are known to sensitize predominantly spinal afferents, this mechanism may contribute to reflex inhibition of intestinal motility during POI.     

Accuracy of a point-of-care blood gas analyzer in gastric tonometry measurements of intramucosal pH (pHi) and P<Subscript>CO</Subscript><Subscript>2</Subscript> gap

Purpose We assessed the accuracy of a point-of-care blood gas analyzer in providing data from saline samples obtained by gastrointestinal tonometry (Tonometrics Catheter; Tonometrics Division, Instrumentarium, Helsinki, Finland) for the calculation of intramucosal pH (pHi) and the P_CO2 gap (intramucosal P_CO2 – Pa_CO2).Methods We compared the point-of-care analyzer (Opti; AVL Medical Instruments, Schaffhausen, Switzerland; Opt) with a conventional analyzer (Compact 2 AVL Medical Instruments, Schaffhausen; Elect) in a clinical study (Elect being taking as the standard). In an in vitro study, P_CO2 data of tonometer saline (Pr_CO2) from Opt and Elect were compared with P_CO2 data from a continuous air tonometer (Tonocap Tonometrics Division, Instrumentarium) for a bottle containing a mixed P_CO2 gas. Data were evaluated by the Bland-Altman method.Results In the clinical study, the bias (B) and precision (P) were: B = 0.223 and P = 0.056 for pHi, B = –14.0 and P = 2.43 (mmHg) for Pr_CO2, and B = –16.7 and P = 2.6 (mmHg) for the P_CO2 gap (n = 27). In the in vitro study, the bias between the two values (Pr_CO2 and bottle P_CO2) was –1.98mmHg and precision was 1.23mmHg for Elect, but for Opt, these values were –22.09mmHg and 3.15mmHg, respectively (n = 18).Conclusion Opt is not suitable for measuring pHi and the P_CO2 gap because it does not provide an accurate P_CO2 for tonometry saline.Part of this study was presented at the 20th International Symposium on Intensive Care and Emergency Medicine (Brussels, March, 2000).     

Effect of pelvic floor muscle contraction on vesical and rectal function with identification of puborectalis-rectovesical inhibitory reflex and levator-rectovesical excitatory reflex

 The effects of pelvic floor muscle contraction on rectal and vesical function were studied in 19 healthy volunteers with the aim of shedding light on some of the hitherto vague aspects of the mechanisms involved in micturition and defecation and their disorders. Rectal and vesical pressures were recorded during puborectalis (PR) and levator ani (LA) muscle stimulation with the rectum or urinary bladder empty and full. Muscle stimulation was effected by needle EMG electrode. The pressure responses to stimulation of the PR and LA muscles were also recorded with these muscles and the rectum and urinary bladder individually anesthetized in 12 of the 19 subjects. The test was repeated using saline instead of xylocaine. PR and LA muscle stimulation produced no pressure response in the empty rectum or bladder. Upon rectal balloon distension with a mean of 156.6 ± 34.2 ml of carbon dioxide the mean rectal pressure was 64.6 ± 18.7 cm H₂O, the subject felt the urge to evacuate and the balloon was expelled to the exterior. On PR muscle stimulation at rectal distension with the above volume, the subject did not feel the urge to evacuate, the rectal pressure was 8.2 ± 1.6 cm H₂O and the balloon was not expelled. Upon LA stimulation at the same volume, the urge persisted, the rectal pressure was higher and the balloon was expelled. Vesical filling with a mean of 378.2 ± 23.6 ml of saline initiated the urge to urinate and elevated the vesical pressure. PR muscle stimulation at this volume aborted the urge and pressure elevation, while LA stimulation caused more elevation of the vesical pressure and spontaneous micturition. Bladder filling with a mean of 423.6 ± 38.2 ml produced high vesical pressure and spontaneous urination, both of which were prevented by PR muscle stimulation but not by LA muscle stimulation. Stimulation of the PR and LA muscles during individual anesthetization of the rectum, bladder or PR and LA muscles resulted in no significant rectal or vesical pressure changes. Repetition of the test using saline instead of xylocaine resulted in rectal and vesical pressure responses similar to those without the use of saline. In conclusion, the decline in rectal and vesical responses upon PR muscle contraction indicates a reflex relationship which we term `puborectalis rectovesical inhibitory reflex'. This reflex is suggested to abort the urge to defecate or urinate. In contrast, LA muscle contraction produced rectal and vesical pressure elevation which is suggested to be mediated through the `levator rectovesical excitatory reflex'. `This reflex is probably evoked to promote rectal and vesical evacuation.     

Effects of nicardipine-induced hypotension on cerebrovascular carbon dioxide reactivity in patients with diabetes mellitus under sevoflurane anesthesia

Purpose The purpose of this study was to examine the effects of nicardipine-induced hypotension on cerebrovascular CO₂ reactivity in patients with diabetes mellitus under sevoflurane anesthesia. Methods Nineteen diabetic patients, and 11 nondiabetic patients (serving as controls), undergoing elective orthopedic, cardiovascular, or thoracic surgery were included in the study. The diabetic patients were divided into three groups according to the antidiabetic therapy they were receiving, i.e., diet therapy (n = 6), oral antidiabetic drugs (n = 7), and insulin (n = 6). Anesthesia was maintained with 1.0 minimum alveolar concentration of sevoflurane. Absolute and relative cerebrovascular CO₂ reactivity was calculated using a 2.5-MHz pulsed transcranial Doppler (TCD) probe for the continuous measurement of mean blood flow velocity in the middle cerebral artery (Vmca). The cerebrovascular CO₂ reactivity was measured both at baseline and during hypotension by increasing the ventilatory frequency by 4 to 7 breaths·min⁻¹. Nicardipine was used to induce hypotension. Results We found that values for the Bispectral index (BSI), baseline mean blood pressure, endtidal CO₂ (Pet_{CO 2}), and Vmca were essentially identical in all patients, irrespective of the type of antidiabetic treatment being taken. Values for absolute and relative CO₂ reactivity in insulin-dependent patients, at both baseline blood pressure and during hypotension, were lower than those in patients in the antidiabetic drug, diet, and control groups (during hypotension, absolute CO₂ reactivity: diet group: 3.2 ± 0.9; oral antidiabetic drug group: 3.2 ± 0.7; insulin group: 1.5 ± 0.6; control group: 3.4 ± 0.8 cm·s⁻¹·mmHg⁻¹, [P < 0.05 insulin group vs the other groups]; relative CO₂ reactivity: diet group, 6.3 ± 1.0; oral antidiabetic drug group, 6.5 ± 0.8; insulin group, 3.5 ± 0.8; control group, 6.5 ± 0.7%·mmHg⁻¹, [P < 0.05 insulin group vs the other groups]. Conclusion We concluded that cerebrovascular CO₂ reactivity in insulin-dependent patients is impaired during nicardipine-induced hypotension under sevoflurane anesthesia.     

Intracellular alkalosis stimulates potassium secretion in rabbit CCD

Background. Clinically, it is well known that alkalosis induces hypokdemia, but the precise mechanisms of these interactions between acid-base disturbances and potassium homeostasis are not known with certainty. The role of intracellular alkalosis in the regulation of transepithelial potassium transport was examined in rabbit cortical collecting ducts (CCD). Methods. Intracellular alkalosis was induced by 25 mM N-2 hydroxyethylpiperazine-N′-2-ethanesulfonic acid (HEPES) buffer in which bicarbonate and CO₂ were eliminated. Intracellular pH (pHi) was measured by the load of 2′,7′-bis(2-carboxyethyl)-5(6)-carboxyfluorescein (BCECF) dye in principal cells. Isolated CCD was perfused in vitro, and electrophysiological studies and electrolyte transport studies were performed with or without HEPES buffer. Results. Basal pHi in the Krebs-Ringer-Bicarbonate solution was 7.11 ± 0.06. Alkalization by HEPES buffer solution (pH 7.4) resulted in pHi 7.54 ± 0.16. Intracellular alkalization induced by HEPES solution significantly hyperpolarized transepithelial voltage, while net potassium flux increased from −17.3 ± 3.6 to −21.0 ± 3.4 pmol·min⁻¹·mm⁻¹. However, lumen-to-bath isotope sodium flux did not change. The basolateral membrane voltage of the principal cells increased from −74.6 ± 3.0 to −79.6 ± 2.9 mV and transepithelial resistance decreased significantly from 113.1 ± 2.7 to 100.9 ± 20.1 Ω·cm². The calculated fractional resistance of the apical membrane decreased, indicating that intracellular alkalosis increases apical potassium conductance. In the presence of either basolateral ouabain, luminal amiloride, or luminal barium, the HEPES-induced hyperpolarization was preserved. Conclusion. The present study demonstrates that intracellular pH is an important determinant of apical potassium conductance in CCD. Additionally, it should be noted that in the experiments using HEPES buffer solution, intracellular pH in certain epithelial cells was alkalinized by the elimination of bicarbonate and CO₂. Received: April 30, 1998 / Accepted: December 7, 1998     

Effects of olprinone on hepatosplanchnic circulation and mitochondrial oxidation in a porcine model of endotoxemia

Purpose This study was performed in order to assess the effects of olprinone, a phosphodiesterase III inhibitor, on hepatic oxygen delivery (DO₂H), oxygen consumption (VO₂H), and mitochondrial oxidation in the liver of a porcine endotoxemia model. Methods Fourteen pigs received continuous infusion of endotoxin via the portal vein for 240 min. From t = 150 to t = 240 min, animals were randomly divided into two groups to receive saline (control [CONT]; n = 7), or olprinone (OLP; n = 7) via the central vein. Results In the OLP group, prior to olprinone treatment at 150 min, endotoxin induced significant decreases in the cardiac index (CI; from 120 ± 31 to 65 ± 13 ml·kg⁻¹·min⁻¹; P < 0.01) and DO₂H (from 3.58 ± 0.81 to 1.55 ± 0.49 ml·kg⁻¹·min⁻¹; P < 0.01), while VO₂H was maintained. After administration of olprinone (from t = 150 to t = 240 min), CI was unchanged, while DO₂H increased from 1.55 ± 0.49 to 1.93 ± 0.38 ml·kg⁻¹·min⁻¹ (P < 0.01) and VO₂H increased from 0.42 ± 0.28 to 0.69 ± 0.38 ml·kg⁻¹·min⁻¹ (P < 0.01). At t = 240 min, the oxidation level of cytochrome aa3 was significantly higher in the OLP group than in the CONT group (OLP, 66.2 ± 19.3% vs CONT, 26.4 ± 17.3%; P < 0.01). Conclusion Our data for this porcine endotoxemia model suggest that olprinone may have beneficial therapeutic effects in restoring not only systemic and hepatic circulation but also mitochondrial oxidation in the liver.     

Assessment of the Relationship Between Post-meal Satiety, Gastric Volume and Gastric Emptying After Swedish Adjustable Gastric Banding. A Pilot Study Using Magnetic Resonance Imaging to Assess Postsurgery Gastric Function

Background  Swedish adjustable gastric banding (SAGB) is a common weight loss procedure performed worldwide. The exact mechanism by which it achieves appetite suppression, and hence weight loss, is not clear. One possible mechanism is altered meal handling by the post-SAGB stomach. Methods  Five post SAGB patients and five age/sex-matched controls were recruited. Pre- and post-meal magnetic resonance imaging (MRI) was performed with two liquid test meals of differing viscosity—locust bean gum (3.0%) and water. Appetite was assessed using ten-point visual analogue scales. Results  There were significant relationships between hunger scores and esophageal, pouch and residual stomach fluid volume changes for the locust bean gum meal (p = 0.033, 0.043 and 0.011, respectively). The rate constants for gastric emptying were similar in the two groups for both the gum (0.038 ± 0.016 min⁻¹ for SAGB, 0.041 ± 0.032 min⁻¹ for controls, p = 0.44) and water meals (0.068 ± 0.044 min⁻¹ for SAGB, 0.044 ± 0.009 min⁻¹ for controls, p = 0.35). An unexpected finding was asymptomatic esophageal meal retention with the locust bean gum meal in the post-SAGB arm (mean 16.9 ml at 15 min). Conclusions  There is no evidence of differences in volume-dependent gastric emptying between the normal and post-SAGB stomach. Further investigation of the phenomenon of esophageal retention, and its role in post-SAGB satiety, is warranted.     

Effect of peak inspiratory flow on gas exchange, pulmonary mechanics, and lung histology in rabbits with injured lungs

Purpose The aim of this study was to evaluate, using a rabbit model, the little-known effect of different levels of peak inspiratory flow on acutely injured lungs. Methods Fourteen male rabbits (body weight, 2711 ± 146 g) were anesthetized and their lungs were injured by alveolar overstretch with mechanical ventilation until Pa_O2 was reduced below 300 mmHg. Injured animals were randomly assigned to: the P group—to receive pressure-regulated volume-control ventilation (PRVCV; n = 7); and the V group—to receive volume-control ventilation (VCV; n = 7). Other ventilator settings were: fraction of inspired oxygen (FI_O2), 1.0; tidal volume, 20 ml·kg⁻¹; positive end-expiratory pressure (PEEP) 5 cmH₂O; and respiratory rate, 20 min⁻¹. The animals were thus ventilated for 4 h. Throughout the protocol, ventilatory parameters and blood gas were measured every 30 min. After the protocol, the lung wet-to-dry ratio and histological lung injury score were evaluated in the excised lungs. Results Throughout the protocol, peak inspiratory flow and mean inspiratory flow values in the P group were significantly higher than those in the V group (26.7 ± 5.0 l·min⁻¹ vs 1.2 ± 0.2 l·min⁻¹, and 4.3 ± 0.3 l·min⁻¹ vs 1.1 ± 0.1 l·min⁻¹; P < 0.05). The wet-to-dry ratio in the P group was also significantly higher than that in the V group (7.7 ± 0.9 vs 6.3 ± 0.5; P < 0.05). More animals in the P group than in the V group had end-of-protocol Pa_O2/FI_O2 ratios below 200 mmHg (43% vs 0%; P = 0.06). Conclusion In rabbits with injured lungs, high peak inspiratory flow with high tidal volume (V_T) reduces the Pa_O2/FI_O2 ratio and increases the lung wet-to-dry ratio.     

Gastric mucosal end-tidal PCO2 difference as a continuous indicator of splanchnic perfusion

Gastric mucosal and arterial blood PCO₂ must be known to assessmucosal perfusion by means of gastric tonometry. As end-tidalPCO₂ (PE'_CO2) is a function of arterial PCO₂, the gradient betweenPE'_CO2 and gastric mucosal PCO₂ may reflect mucosal perfusion.We studied the agreement between two methods to monitor gutperfusion. We measured the difference between gastric mucosalPCO₂ (air tonometry) and PE'_CO2 (=DPCO_2gas) and the differencebetween gastric mucosal PCO₂ (saline tonometry) and arterialblood PCO₂ (=DPCO_2sal) in 20 patients with or without lung injury.DPCO_2gas was greater than DPCO_2sal but changes in DPCO_2gas reflectedchanges in DPCO_2sal. The bias between DPCO_2gas and DPCO_2salwas 0.85 kPa and precision 1.25 kPa. The disagreement betweenDPCO_2gas and DPCO_2sal increased with increasing dead space.We propose that the disagreement between the two methods studiedmay not be clinically important and that DPCO_2gas may be a methodfor continuous estimation of splanchnic perfusion. Br J Anaesth 2000; 85: 563–9 ^* Corresponding author: Department of Anesthesiology and IntensiveCare, Division of Critical Care, Kuopio University Hospital,PO Box 1777, FIN-70211 Kuopio, Finland     

Strontium oral load test in children with idiopathic hypercalciuria

Increased intestinal calcium absorption may play an important role in the pathogenesis of idiopathic hypercalciuria in children. Calcium absorption was assessed by an oral strontium load test in 22 prepubertal children (13 male) with idiopathic hypercalciuria, urinary calcium excretion 6.48 ± 0.60 mg/kg per day (range 4.12–13.40 mg/kg per day), and ten healthy, young, normocalciuric controls (six male). After administration of 2.65 mg/kg of strontium chloride (SrCl₂), the serum concentrations of strontium at 30 min, 60 min, 120 min, 240 min, and the fraction of the absorbed dose (FAD%) at 30 min, 60 min and 240 min, were similar in both groups. FAD% at 120 min was lower (P < 0.05) in hypercalciuric children than in controls (11.84 ± 0.96% vs 15.87 ± 1.77%). Values of the area under the curve were not different between both groups. In children with idiopathic hypercalciuria, serum basal intact parathyroid hormone (PTH) (r = −0.59, P = 0.004) and the 1,25-dihydroxyvitamin D/PTH ratio (r = 0.65; P = 0.001) were correlated with the serum concentration of strontium at 60 min. The study reported here provides, for the first time, the results of a strontium oral load test in children with idiopathic hypercalciuria. With this method no major alterations of intestinal calcium absorption were found in this disorder.     

Comparison of effects of diode laser and CO<Subscript>2</Subscript> laser on human teeth and their usefulness in topical fluoridation

Various authors have reported more effective fluoridation from the use of lasers combined with topical fluoride than from conventional topical fluoridation. Besides the beneficial effect of lasers in reducing the acid solubility of an enamel surface, they can also increase the uptake of fluoride. The study objectives were to compare the action of CO₂ and GaAlAs diode lasers on dental enamel and their effects on pulp temperature and enamel fluoride uptake. Different groups of selected enamel surfaces were treated with amine fluoride and irradiated with CO₂ laser at an energy power of 1 or 2 W or with diode laser at 5 or 7 W for 15 s each and compared to enamel surfaces without treatment or topical fluoridated. Samples were examined by means of environmental scanning electron microscopy (ESEM). Surfaces of all enamel samples were then acid-etched, measuring the amount of fluoride deposited on the enamel by using a selective ion electrode. Other enamel surfaces selected under the same conditions were irradiated as described above, measuring the increase in pulp temperature with a thermocouple wire. Fluorination with CO₂ laser at 1 W and diode laser at 7 W produced a significantly greater fluoride uptake on enamel (89 ± 18 mg/l) and (77 ± 17 mg/l) versus topical fluoridation alone (58 ± 7 mg/l) and no treatment (20 ± 1 mg/l). Diode laser at 5 W produced a lesser alteration of the enamel surface compared to CO₂ laser at 1 W, but greater pulp safety was provided by CO₂ laser (ΔT° 1.60° ± 0.5) than by diode laser (ΔT° 3.16° ± 0.6). Diode laser at 7 W and CO₂ laser at 2 W both caused alterations on enamel surfaces, but great pulp safety was again obtained with CO₂ (ΔT° 4.44° ± 0.60) than with diode (ΔT° 5.25° ± 0.55). Our study demonstrates that CO₂ and diode laser irradiation of the enamel surface can both increase fluoride uptake; however, laser energy parameters must be carefully controlled in order to limit increases in pulpal temperature and alterations to the enamel surface.     

Comparison of oesophageal and gastric air tonometry in patients with circulatory failure

Background. Gastric PCO₂ measured by balloon tonometry can estimatethe adequacy of splanchnic perfusion. However, enteral feedingand gastric content can interfere with gastric PCO₂ assessment.Tonometry in other sites of the body could avoid these problems.We therefore tested the hypothesis that oesophageal air tonometrywould give results similar to gastric tonometry. Methods. We studied 20 consecutive patients (mean age 68 (SD9) [range 49–81] yr, 18 males, SAPS II score 55 (SD 18),ICU mortality 55%) with circulatory disorders during mechanicalventilation in the intensive care unit. Tonometer probes wereplaced via the nose, one into the stomach and the other in theoesophagus. PCO₂ was measured with two automated gas analysers,at admission and 30 min, 1, 2, 3, 32, 40, and 48 h thereafter. Results. One hundred and forty-eight paired measurements wereobtained. Gastric PCO₂ was greater than oesophageal PCO₂ onadmission (7.19 (1.43) vs 5.89 (0.73) kPa, P<0.01) and subsequently.Differences between the measures correlated (r=0.67) with themean absolute value, indicating that overestimation increasedas gastric PCO₂ increased. Conclusions. Oesophageal PCO₂ is less than gastric PCO₂, andthe difference is greater when gastric PCO₂ levels are greater.Air tonometry may not measure regional PCO₂ levels in the oesophagussatisfactorily. Other methods and sites for carbon dioxide tonometryshould be examined. Br J Anaesth 2002; 89: 237–41     

Genotype–phenotype correlation in children with autosomal dominant polycystic kidney disease

Adults with autosomal dominant polycystic kidney disease (ADPKD) and PKD1 mutations have a more severe disease than do patients with PKD2 mutations. The aim of this study was to compare phenotypes between children with mutations in the PKD1/PKD2 genes. Fifty PKD1 children and ten PKD2 children were investigated. Their mean age was similar (8.6 ± 5.4 years and 8.9 ± 5.6 years). Renal ultrasound was performed, and office blood pressure (BP), ambulatory BP, creatinine clearance and proteinuria were measured. The PKD1 children had, in comparison with those with PKD2, significantly greater total of renal cysts (13.3 ± 12.5 vs 3.0 ± 2.1, P = 0.004), larger kidneys [right/left kidney length 0.89 ± 1.22 standard deviation score (SDS) vs 0.17 ± 1.03 SDS, P = 0.045, and 1.19 ± 1.42 SDS vs 0.12 ± 1.09 SDS, P = 0.014, successively] and higher ambulatory day-time and night-time systolic BP (day-time/night-time BP index 0.93 ± 0.10 vs 0.86 ± 0.05, P = 0.021 and 0.94 ± 0.07 vs 0.89 ± 0.04, P = 0.037, successively). There were no significant differences in office BP, creatinine clearance or proteinuria. Prenatal renal cysts (14%), hypertension defined by ambulatory BP (27%) and enlarged kidneys (32%) were observed only in the PKD1 children. This is the first study on genotype–phenotype correlation in children with ADPKD. PKD1 children have more and larger renal cysts, larger kidneys and higher ambulatory BP than do PKD2 children. Renal cysts and enlarged kidneys detected prenatally are highly specific for children with PKD1.     

Boussignac CPAP in the Postoperative Period in Morbidly Obese Patients

Background In the postoperative period hypoventilation and hypoxia with hypercarbia may occur in morbidly obese patients due to the residual influence of general anesthesia drugs, postoperative atelectasis and postoperative pain. Non-Invasive Ventilation (NIV) is a method of improvement of respiratory efficiency in patients not requiring mechanical ventilation. The aim of the study was to compare NIV (Boussignac) CPAP and traditional oxygen delivery via nasal catheter in the postoperative acute care unit (PACU) in morbidly obese patients after open Roux-en-Y gastric bypass (RYGBP). Methods 19 morbidly obese patients scheduled for elective open RYGBP, were randomly divided into 2 groups: CPAP (10 patients) or control (nasal catheter – 9 patients). Patients consisted of: 8 male and 11 female, mean weight 127.76 ± 18.5 kg, height 173.41 ± 9.41 cm, BMI 42.43 ± 3.3 kg/m2, age 35.84 ± 9.05 years. In the PACU, capillary blood gas measurements were taken at 3 Time Points: T1 – 30 min, T2 – 4 hours and T3 – 8 hours after admission. Sample T0 was taken before surgery. For management of postoperative pain, patients received morphine 2 mg/h intravenously and tramadol 100 mg. Results Mean blood gas measurements of all postoperative time points were: pO₂ 81.0 ± 16.0 (range 78.1–85.7) mmHg vs 65.9 ± 4.9 (range 63.8–68.1) mmHg (P < 0.05); pCO₂ 40.6 ± 2.4 (range 39.4–41.8) mmHg vs 41.5 ± 4.0 (range 39.6–43.4) mmHg (P > 0.05), in the CPAP and control groups respectively. In every case, pulse-oxymetry oxygenation was >94%. Conclusion Boussignac CPAP improved blood oxygenation compared to passive oxygenation with a nasal catheter but had no influence on CO₂ elimination in non-CO₂ retaining morbidly obese patients.     

Renal hemodynamic changes and renal functional reserve in children with type I diabetes mellitus

Increased glomerular filtration rate (GFR) has been implicated in the development of diabetic nephropathy. Large normal interindividual variations of GFR hamper the diagnosis of renal hemodynamic alterations. We examined renal functional reserve (RFR) in children with type 1 diabetes mellitus to assess whether hyperfiltration occurs. The renal hemodynamic response following dopamine infusion was examined in 51 normoalbuminuric diabetic children (7.7 ± 3.6 years) with a mean duration of diabetes of 6.2 years and compared them with 34 controls. Mean baseline GFR in diabetic children did not differ from the control population (130.7 ± 22.9 vs. 124.8 ± 25 ml/min per 1.73 m²), whereas renal plasma flow was significantly lower (463.7 ± 103.9 vs. 587.2 ± 105 ml/min per 1.73 m², p < 0.001), and filtration fraction was increased (29 ± 8 vs. 21 ± 2%, p < 0.001), compared with controls. The mean RFR was lower (p < 0.001) than in control subjects (−0.77 ± 23 vs. 21 ± 8 ml/min per 1.73 m²). This study documents an increased filtration fraction and reduced or absent RFR in children with type 1 diabetes mellitus in the stage before apparent nephropathy. GFR values were within normal range. Although the reduced RFR and increased filtration fraction indicate the presence of hemodynamic changes, their relevance to the development of hyperfiltration and subsequent diabetic nephropathy remains unknown.     

Is Lean Body Mass Decreased after Obesity Treatment by Adjustable Gastric Banding?

Background There is concern that surgically-induced weight loss in obese subjects is associated with a disproportionate decrease in lean body mass (LBM) and in skeletal muscle mass (SMM), a major constituent of LBM. To address this issue, 1) we measured total and regional body composition following gastric banding in a group of obese subjects, and 2) we compared these data to those of a non-surgical control group of similar age and body size. Methods Body composition was assessed by dualenergy X-ray absorptiometry (DEXA) before and after laparoscopic adjustable silicone gastric banding (LAGB) in 32 women (after 1 year: age 43.7 ± 8.4 years, BMI 36.4 ± 5.9 kg/m², mean ± SD), and in 117 control women (age 44.5 ± 7.5 years; BMI 36.7 ± 5.5 kg/m²) referred for non-surgical weight management, prior to weight loss. SMM was estimated using a published equation based on LBM of the extremities (appendicular LBM). Results 1 year after LAGB, body weight loss (−23.7 ± 11.6 kg, P < 10⁻⁶) was mainly due to decreased fat mass (−21.2 ± 11.2 kg, P < 10⁻⁶), and total LBM was modestly, although significantly, decreased (−2.1 ± 4.2 kg, P = 0.01). Appendicular LBM (−0.7 ± 2.7 kg) and total SMM (−0.9 ± 3.0 kg) were not significantly modified. None of the body composition variables was significantly decreased in weight-reduced subjects compared to the control group, especially appendicular LBM and total SMM. Conclusions Results provide no evidence for a decrease in appendicular LBM and total SMM with weight loss following LAGB. Follow-up of these obese patients revealed a very favorable pattern of change in total and regional body composition, with preservation of muscle mass.     

Prevention of postoperative nausea and vomiting in children following adenotonsillectomy,using tropisetron with or without low-dose dexamethasone

Purpose Postoperative nausea and vomiting (PONV) after adenotonsillectomy in children is, in spite of the prophylactic administration of tropisetron, still a frequent event. The aim of this study was to evaluate the benefit of the additional systemic administration of low-dose dexamethasone (0.15 mg·kg⁻¹) for the prevention of PONV. Methods With hospital ethics committee approval, we investigated children undergoing adenotonsillectomy receiving tropisetron (0.1 mg·kg⁻¹; maximum dose, 2 mg) or tropisetron (0.1 mg·kg⁻¹; maximum dose, 2 mg) plus dexamethasone (0.15 mg·kg⁻¹; maximum dose, 6 mg) intraoperatively. The incidence of vomiting episodes and the need for postoperative analgesics were recorded. Patient data were analyzed using the t-test and the χ² test (significance level of P = 0.05). Data values are means ± SD. Results Ninety children (39 girls and 51 boys), aged 5.6 ± 2.8 years and weighing 21.9 ± 8.8 kg, were enrolled in the study. The overall incidence of vomiting was 38.9% within the first 24 h (67 vomiting events) and 44.4% within 48 h postoperatively (87 vomiting events). The incidence of vomiting in the tropisetron-only group was 53.3% (24/45) at 24 h and 60% (27/45) at 48 h (24 h: P < 0.001 and 48 h: P = 0.04) and 24.4% (11/45) at 24 h and 28.9% (13/45) at 48 h in the tropisetron-dexamethasone group. The need for postoperative nalbuphine was double in patients treated with tropisetron-dexamethasone (0.61 mg ± 0.36 mg·kg⁻¹·48 h⁻¹) compared to that in patients receiving only tropisetron (0.31 mg ± 0.28 mg·kg⁻¹·48 h⁻¹; P < 0.0001). Conclusion A low-dose bolus of dexamethasone (0.15 mg·kg⁻¹) in combination with tropisetron, compared to tropisetron alone, considerably reduced the incidence of vomiting in children following pediatric adenotonsillectomy.     

Evaluation of cerebrovascular carbon dioxide reactivity in patients with diabetes mellitus under sedative doses of propofol

The present study compared cerebrovascular CO₂ reactivity in diabetic patients on different treatment modalities under sedative doses of propofol. Fifteen patients with diabetes mellitus (on three different antidiabetic treatment modalities) who required mechanical ventilation during intensive care therapy were studied, sedation during mechanical ventilation being maintained using propofol. As controls, 6 patients without diabetes were monitored. A 2.5-MHz pulsed transcranial Doppler probe was attached to the head of the patient at the right temporal window for continuous measurement of mean blood flow velocity in the middle cerebral artery (Vmca). After establishing baseline values of Vmca and cardiovascular hemodynamics, end-tidal CO₂ was decreased by increasing ventilatory frequency by 5–8 breaths·min⁻¹. Values for absolute and relative CO₂ reactivity in insulintreated patients were lower than those in the other three groups (absolute CO₂ reactivity [means ± SD]: control, 3.1 ± 0.6 cm·s⁻¹·mmHg⁻¹, diet, 3.8 ± 1.4 cm·s⁻¹·mmHg⁻¹; oral antidiabetic drug 3.2 ± 0.9 cm·s⁻¹·mmHg⁻¹; insulin, 1.1 ± 0.6 cm·s⁻¹·mmHg⁻¹; P = 0.002). The present study shows that insulin-treated diabetic patients probably have lower cerebrovascular CO₂ reactivity under propofol anesthesia than control patients or diabetics treated with dietary therapy or oral hypoglycemics.     

LCT 13910 C/T polymorphism, serum calcium, and bone mineral density in postmenopausal women

Summary  LCT 13910 CC genotype is associated with lactose intolerance, a condition often resulting in reduced milk intake. Women with the CC genotype were found to have decreased serum calcium and reduced bone mineral density. Introduction  The CC genotype of the 13910 C/T polymorphism of the LCT gene is linked to lactose intolerance and low calcium intake. Methods  We studied 595 postmenopausal women, including 267 osteoporotic, 200 osteopenic, and 128 healthy subjects. Genotyping, osteodensitometry, and laboratory measurements were carried out. Results  Frequency of aversion to milk consumption was 20% for CC genotype and 10% for TT + TC genotypes (p = 0.03). The albumin-adjusted serum calcium was 2.325 ± 0.09 mmol/L for CC genotype and 2.360 ± 0.16 mmol/L for TT + TC genotypes (p = 0.031). Bone mineral density (BMD; Z score) was lower in the CC than TT + TC genotypes, respectively, at the radius (0.105 ± 1.42 vs 0.406 ± 1.32; p = 0.038), at the total hip (−0.471 ± 1.08 vs −0.170 ± 1.09; p = 0.041), and at the Ward’s triangle (−0.334 ± 0.87 vs −0.123 ± 0.82; p = 0.044). Conclusion  LCT 13910 C/T polymorphism is associated with decreased serum calcium level and lower BMD in postmenopausal women. Péter Lakatos and Gábor Speer contributed equally to this work.     

Height and bone mineral density in androgen insensitivity syndrome with mutations in the androgen receptor gene

Introduction and hypothesis Androgen insensitivity syndrome (AIS) constitutes a natural model to study effects of androgens and estrogens on growth and bone density. We evaluated height and bone density in patients with AIS with mutations in the androgen receptor (AR) gene. Methods A retrospective analysis was conducted of eight subjects with complete AIS (CAIS) and four with partial AIS (PAIS) submitted to gonadectomy followed by estrogen replacement, and three with PAIS who did not undergo gonadectomy. Standing height and bone mineral apparent density (BMAD) by DXA were measured and compared with male (z _m) and female (z _f) reference populations. The z-scores were compared with a value of zero using the one-sample t-test. Results Final heights of patients with CAIS and PAIS were intermediate between those predicted for females and males. BMAD of the lumbar spine in CAIS and PAIS after gonadectomy and estrogen replacement (z _f = − 1.56 ± 1.04, P = 0.006, and z _m = − 0.75 ± 0.89, P = 0.04) indicated vertebral bone deficit, whereas BMAD at the femoral neck was normal. No patient reported fractures. Conclusion Subjects with AIS had mean final height intermediate between mean normal male and female, and decreased bone mineral density in the lumbar spine. These data suggest an important role for androgens in normal male growth and bone density not replaced by estrogens.