Corrected flow time (FTc) by oesophageal Doppler is considered to be a 'static' preload index. We evaluated the ability of FTc to predict fluid responsiveness and compared this with the abilities of other preload indices, such as pulse pressure variation (PPV), central venous pressure (CVP), and left ventricular end-diastolic area index (LVEDAI). Twenty neurosurgical patients were studied. After induction of anaesthesia, FTc, PPV, LVEDAI, CVP, and stroke volume index (SVI) were measured before and 12 min after fluid loading with 6% hydroxyethyl starch solution (7 ml kg(-1)). Responders and non-responders were defined as those patients with an SVI increase >or= 10% or < 10% after fluid loading, respectively. Pearson's correlation was used to assess correlations between changes in SVI and initial haemodynamic variables. Receiver operating characteristic (ROC) curves were constructed and compared to evaluate the overall performance of preload indices (FTc, PPV, LVEDAI, and CVP) in terms of predicting fluid responsiveness. FTc and PPV before fluid loading differed between responders (n = 11) and non-responders (n = 9), and correlated with changes in SVI (r = -0.515 and r = 0.696, respectively), which was opposite to that observed for CVP or LVEDAI. Areas under ROC curves for FTc [0.944 (SD 0.058)] and PPV [0.909 (0.069)] were significantly greater than those for CVP [0.540 (0.133), P < 0.001] and LVEDAI [0.495 (0.133), P < 0.001]. The optimal threshold value given by ROC analysis was 357 ms for FTc. In this study, FTc predicted fluid responsiveness. However, FTc should be used in conjunction with other clinical information.

We performed this study to assess the influence of endotracheal tube (ETT) tip design (Murphy-tip versus Magill-tip) on nasal trauma during nasotracheal intubation with a conventional polyvinyl chloride ETT. Patients were randomly allocated to one of four groups (n = 25 each): Magill-tipped ETT and Murphy-tipped ETT with or without thermosoftening. After preparation with a vasoconstrictor, the selected, well-lubricated ETT was advanced blindly into the nasopharynx, and intubation was completed under direct laryngoscopy. The severity of epistaxis was estimated based on the distance that blood had traveled up the suction catheter and tubing. Without thermosoftening, the Murphy-tipped ETT produced more severe epistaxis than the Magill-tipped ETT (P < 0.05). Thermosoftening effectively reduced the severity of epistaxis for both conventional types of ETT (P < 0.05). However, there was no difference in the severity of epistaxis and the incidence of nasal injury and pain between the Magill-tipped, nonthermosoftened ETT and Murphy-tipped, thermosoftened ETT. Thermosoftening is recommended because it decreases the trauma during nasotracheal intubation. However, if one chooses to use a normal ETT, the Magill-tipped ETT will cause fewer traumas than the Murphy-tipped ETT.

Selective glycolytic inhibition (GI) promotes electromechanical alternans and triggered beats in isolated cardiac myocytes. We sought to determine whether GI promotes triggered activity by early afterdepolarization (EAD) or delayed afterdepolarizations in intact hearts isolated from adult and aged rats. Dual voltage and intracellular calcium ion (Ca_i²⁺) fluorescent optical maps and single cell glass microelectrode recordings were made from the left ventricular (LV) epicardium of isolated Langendorff-perfused adult (∼4 mo) and aged (∼24 mo) rat hearts. GI was induced by replacing glucose with 10 mM pyruvate in oxygenated Tyrode's. Within 20 min, GI slowed Ca_i²⁺transient decline rate and shortened action potential duration in both groups. These changes were associated with ventricular fibrillation (VF) in the aged hearts (64 out of 66) but not in adult hearts (0 out of 18; P < 0.001). VF was preceded by a transient period of focal ventricular tachycardia caused by EAD-mediated triggered activity leading to VF within seconds. The VF was suppressed by the ATP-sensitive K (K_ATP) channel blocker glibenclamide (1 μM) but not (0 out of 7) by mitochondrial K_ATPblock. The Ca-calmodulin-dependent protein kinase II (CaMKII) blocker KN-93 (1 μM) prevented GI-mediated VF ( P < 0.05). Block of Na-Ca exchanger (NCX) by SEA0400 (2 μM) prevented GI-mediated VF (3 out of 6), provided significant bradycardia did not occur. Aged hearts had significantly greater LV fibrosis and reduced connexin 43 than adult hearts ( P < 0.05). We conclude that in aged fibrotic unlike in adult rat hearts, GI promotes EADs, triggered activity, and VF by activation of K_ATPchannels CaMKII and NCX.