Psychopharmacological modulation of event-related potentials suggests that first-hand pain and empathy for pain rely on similar opioidergic processes.

Accumulating evidence suggests that empathy for pain recruits similar neural processes as the first-hand experience of pain. The pain-related P2, an event-related potential component, has been suggested as a reliable indicator of neural processes associated with first-hand pain. Recent evidence indicates that placebo analgesia modulates this component for both first-hand pain and empathy for pain. Moreover, a psychopharmacological study showed that administration of an opioid antagonist blocked the effects of placebo analgesia on self-report of both first-hand pain and empathy for pain. Together, these findings suggest that the opioid system plays a similar role during first-hand pain and empathy for pain. However, such a conclusion requires evidence showing that neural activity during both experiences is similarly affected by psychopharmacological blockage of opioid receptors. Here, we measured pain-related P2 amplitudes and self-report in a group of participants who first underwent a placebo analgesia induction procedure. Then, they received an opioid receptor antagonist known to block the previously induced analgesic effects. Self-report showed that blocking opioid receptors after the induction of placebo analgesia increased both first-hand pain and empathy for pain, replicating previous findings. Importantly, P2 amplitudes were also increased during both experiences. Thus, the present findings extend models proposing that empathy for pain is partially grounded in first-hand pain by suggesting that this also applies to the underlying opioidergic neurochemical processes.

Resistive load of laryngeal mask airway and ProSeal laryngeal mask airway in mechanically ventilated patients.

BACKGROUND: The ProSeal Laryngeal Mask Airway (PLMA) ventilation tube is narrower and shorter than the standard Laryngeal Mask Airway (LMA) and is without the vertical bars at the end of the tube. In this randomized, crossover study, PLMA and LMA resistances were compared. METHODS: Respiratory mechanics was calculated in 26 anesthetized, mechanically ventilated patients with both LMA and PLMA. The laryngeal mask positioning was fiberoptically evaluated. Differences in the respiratory mechanics of the LMA and the PLMA were attributed to the differences between the laryngeal masks. RESULTS: In the total study population the airway resistance was 1.5 +/- 2.6 hPa.l-1.s-1 (P = 0.005) higher with the PLMA than with the LMA. During the PLMA use, the peak expiratory flow reduced by 0.02 +/- 0.05 l min-1 (P = 0.046), the expiratory resistance increased by 0.6 +/- 1.3 hPa.l-1.s-1 (P = 0.022), and the time constant of respiratory system lengthened by 0.09 +/- 0.18 s (P = 0.023). These differences doubled when the LMA was better positioned than the PLMA, whereas they disappeared when the PLMA was positioned better than the LMA. CONCLUSIONS: The standard LMA offers a lower resistive load than the PLMA. Moreover, the fitting between the laryngeal masks and the larynx, as fiberoptically evaluated, plays a major role in determining the resistive properties of these devices.

Impact of laryngeal mask airway and tracheal tube on pulmonary function during the early postoperative period.

BACKGROUND: The tracheal tube (TT) produces reversible bronchoconstriction and increases pulmonary airway resistance compared to the laryngeal mask airway (LMA). The possible persistence of this effect in the postoperative period has not been studied. The aim of this study was to compare the early postoperative pulmonary function in healthy patients undergoing minor surgical procedures with the LMA or with the TT. METHODS: Sixty patients scheduled for saphenous vein stripping under general anaesthesia were randomised to receive the LMA or the TT. Before anaesthesia and 20 min after LMA or TT removal, pulse oxymetry values (SpO(2)) were recorded and patients performed forced spirometry in the supine position. RESULTS: Preoperative pulmonary function was normal in both groups. There were no differences between groups in the preoperative respiratory function test and SpO(2). Following surgery SpO(2), forced expiratory volume in the first second (FEV1), forced vital capacity (FVC) and peak expiratory flow (PEF) decreased in both groups. The FEV1/FVC did not change in either of the groups. In the TT group, compared to patients using the LMA, there was a greater relative decrease of SpO(2) (2.7 +/- 2.7% vs. 1.3 +/- 2.2%, P=0.017), FEV1 (17.6 +/- 12.2% vs. 8 +/- 17.4%, P=0.008), FVC (15.8 +/- 12.4% vs. 9 +/- 13.4%, P=0.023) and PEF (20.6% +/- 15.3% vs. 8.1 +/- 33.3%, P=0.033). CONCLUSIONS: This study demonstrates greater early postoperative respiratory restrictive syndrome and lower arterial oxygen saturation following tracheal intubation compared to LMA use in patients without respiratory disease.