Increased physiological dead space/tidal volume ratio during exercise in burned children

During a transjugular intrahepatic portosystemic shunt (TIPS) procedure, a Strecker stent was accidently pushed into the superior mesenteric vein. After successful shunt placement, the stent was withdrawn into the hepatic vein. A multipurpose basket catheter was attached to the distal end of the stent and a loop snare to the proximal end. In this way it was possible to stretch the stent and retrieve it percutaneously through the jugular sheath.     

The laryngeal mask airway and positive-pressure ventilation

BACKGROUND: The utility of the laryngeal mask airway during positive-pressure ventilation has yet to be determined. Our study was designed to assess whether significant leaks occurred with positive-pressure ventilation and if leaks were associated with gastroesophageal insufflation. METHODS: Forty-eight patients undergoing elective surgery were studied. After induction of anesthesia and paralysis, controlled ventilation was used with four different peak pressure settings in each patient (15, 20, 25, and 30 cmH2O). The order of ventilator pressure settings was assigned from a randomized block schedule. Data collected included inspiratory and expiratory volumes, qualitative assessments of gastroesophageal insufflation, and leak at the neck. After data collection during laryngeal mask use, the anesthesiologist intubated the trachea and measurements were repeated for tracheal tube ventilation. Leak was calculated by subtracting the expiratory from the inspiratory volume and expressed as a fraction of the inspiratory volume. RESULTS: Ventilation with the laryngeal mask airway was adequate at all ventilation pressures and comparable with tracheal tube ventilation. Leak fraction (mean +/- SD) at 15, 20, 25, and 30 cmH2O for laryngeal mask ventilation were 0.13 +/- 0.15, 0.21 +/- 0.18, 0.25 +/- 0.16 and 0.27 +/- 0.17, respectively, and 0.03 +/- 0.03, 0.05 +/- 0.03, 0.05 +/- 0.03 and 0.04 +/- 0.03, respectively, for tracheal tube ventilation. Leak fractions for ventilation with the laryngeal mask were consistently greater than those measured for tracheal tube ventilation at similar ventilation pressures. Leak fraction with laryngeal mask ventilation increased with increasing airway pressures, whereas leak with tracheal tube ventilation remained unchanged. The frequency of gastroesophageal insufflation ranged from 2.1% at a ventilation pressure of 15 cmH2O to 35.4% at 30 cmH2O. CONCLUSIONS: Ventilation using the laryngeal mask appears to be adequate if airway resistance and pulmonary compliance are normal. Gastroesophageal insufflation of air will become a problem in the presence increased ventilation pressure.     

Laryngeal mask airway vs face mask and Guedel airway during pediatric myringotomy

OBJECTIVE: To compare perioperative conditions when a face mask and Guedel oral airway (FM-OA) or a laryngeal mask airway (LMA) are used to maintain airway patency during bilateral myringotomy with insertion of tympanostomy tubes (BMT). DESIGN: Randomized controlled trial in children's hospital tertiary-care operating rooms. PARTICIPANTS: Fifty healthy children undergoing BMT procedures during halothane--nitrous oxide (N2O) anesthesia. INTERVENTIONS: During BMT we managed the airway by inserting a Guedel oral airway or an LMA. MAIN OUTCOME MEASURES: We recorded the time taken to insert the airway device along with oxygen saturation during the operation and time from the end of surgery to eye opening, response to commands, and home readiness. In addition the surgeon assessed perioperative conditions on a 10-point scale (1, poor, through 10, excellent). RESULTS: Although insertion of the LMA took longer than the Guedel oral airway (mean +/- SD, 9 +/- 2 seconds vs 6 +/- 2 seconds; P < .05), no differences were noted in the actual operating, anesthesia, or recovery times. However, the frequency of hypoxemic episodes was decreased (8% vs 36%, P < .05) and the lowest recorded oxygen saturations were higher (mean +/- SD, 95% +/- 7% vs 88% +/- 12%; P < .05) in the LMA group than in the FM-OA group. Surgeons rated perioperative conditions better when the LMA was used (median score, 9 vs 8; P < .05). CONCLUSION: The LMA is an excellent alternative to the FM-OA technique for airway maintenance in children undergoing BMT procedures during halothane--N2O anesthesia.     

Positive pressure ventilation with the laryngeal mask airway in non-paralysed patients: comparison of sevoflurane and propofol maintenance techniques

Photofrin photodynamic therapy (PDT) has recently received FDA approval for the palliative treatment of totally and partially obstructing esophageal malignancies. However, there is a need for new PDT photosensitizers because Photofrin has a number of undesirable features. The purpose of this study was to evaluate the efficacy of four amine-bearing silicon phthalocyanines--Pc4, Pc10, Pc12 and Pc18--as potential PDT photosensitizers. Equimolar concentrations of these Pc were found to be highly effective at causing the regression of RIF-1 tumors transplanted to C3H/HeN mice. The amount of Pc4 necessary to cause an equivalent amount of tumor regression in this model system was substantially less than the amount of Photofrin. The cutaneous phototoxicity of the silicon Pc photosensitizer was assessed by the utilization of the murine ear-swelling model. When C3H mice were exposed to 167 J/cm2 of polychromatic visible light from a UVB-filtered solar simulator, which emitted UV radiation and visible light above 320 nm, the Pc produced little, if any, cutaneous photosensitivity. These results indicate that Pc4, Pc10, Pc12 and Pc18 are at least as effective as Photofrin in PDT protocols, while at the same time addressing many of the drawbacks of Photofrin.     

The laryngeal mask airway in emergency medicine, neonatal resuscitation, and intensive care medicine

In assessing the potential role of the LMA outside the operating room, the risks of a less secure airway must be balanced against the benefits of ease of training, success and speed of insertion, no need for direct visualization of laryngeal structures, and lesser need for ancillary equipment. The LMA has a role as an alternative to FMV in CPR when personnel skilled in tracheal intubation are not available. When skilled intubators are present, it has an important role as an alternative airway when intubation has been impossible. These roles extend to the prehospital setting, with an additional specific indication for its use when access to a patient is limited making tracheal intubation impossible. The LMA is incorporated into advanced life support training and as such should be regarded as a device providing temporary airway support, rather than a replacement for a tracheal tube. The LMA, and possibly also the ILM, should be standard equipment carried by prehospital trauma teams and by all those attending victims in the field.     

Role of tidal volume, FRC, and end-inspiratory volume in the development of pulmonary edema following mechanical ventilation

Mechanical ventilation with high peak inspiratory pressure and large tidal volume (VT) produces permeability pulmonary edema. Whether it is mean or peak inspiratory pressure (i.e., mean or end-inspiratory volume) that is the major determinant of ventilation-induced lung injury is unsettled. Rats were ventilated with increasing tidal volumes starting from different degrees of FRC that were set by increasing end-expiratory pressure during positive-pressure ventilation. Pulmonary edema was assessed by the measurement of extravascular lung water content. The importance of permeability alterations was evaluated by measurement of dry lung weight and determination of albumin distribution space. Pulmonary edema with permeability alterations occurred regardless of the value of positive end-expiratory pressure (PEEP), provided the increase in VT was large enough. Similarly, edema occurred even during normal VT ventilation provided the increase in PEEP was large enough. Furthermore, moderate increases in VT or PEEP that were innocuous when applied alone, produced edema when combined. The effect of PEEP was not the consequence of raised airway pressure but of the increase in FRC since similar observations were made in animals ventilated with negative inspiratory pressure. However, although permeability alterations were similar, edema was less marked in animals ventilated with PEEP than in those ventilated with zero end-expiratory pressure (ZEEP) with the same end-inspiratory pressure. This "beneficial" effect of PEEP was probably the consequence of hemodynamic alterations. Indeed, infusion of dopamine to correct the drop in systemic arterial pressure that occurred during PEEP ventilation resulted in a significant increase in pulmonary edema. In conclusion, rather than VT or FRC value, the end-inspiratory volume is probably the main determinant of ventilation-induced edema. Hemodynamic status plays an important role in modulating the amount of edema during lung overinflation but does not fundamentally modify the characteristics of this edema which is consistently associated with major permeability alterations. These results may be relevant for ventilatory strategies during acute respiratory failure.     

Morningness/eveningness, morning-to-afternoon cortisol ratio, and antisocial behavior problems during puberty.

The relationship between morningness/eveningness (M/E) and morning-to-afternoon cortisol ratio, pubertal timing, and antisocial behavior was examined in 111 girls and boys ages 8 to 13 years. Cortisol levels showed a significant increase after awakening and declined thereafter ( p