Nobuko Sasano

A novel skin-traction method is effective for real-time ultrasound-guided internal jugular vein catheterization in infants and neonates weighing less than 5 kilograms.

BACKGROUND:Internal jugular vein (IJV) catheterization in pediatric patients is sometimes difficult because of the small sizes of veins and their collapse during catheterization. To facilitate IJV catheterization, we developed a novel skin-traction method (STM), in which the point of puncture of the skin over the IJV is stretched upward with tape during catheterization. In this study, we examined whether the STM increases the cross-sectional area of the vein and thus facilitates catheterization. METHODS:This was a prospective study conducted from December 2006 to June 2008. We enrolled 28 consecutive infants and neonates weighing <5 kg who underwent surgery for congenital heart disease. The patients were randomly assigned to a group in which STM was performed (STM group) or a group in which it was not performed (non-STM group). The cross-sectional area and diameter of the right IJV in the flat position and 10° Trendelenburg position with and without applying STM were measured. We determined time from first skin puncture to the following: (a) first blood back flow, (b) insertion of guidewire, and (c) insertion of catheter. Number of punctures, success rate, complications, and degree of IJV collapse during advancement of the needle (estimated as decrease of anteroposterior diameter during advancement of the needle compared with the diameter before advancement) were also examined. RESULTS:STM significantly increased the cross-sectional area and the anteroposterior diameter of the IJV in both positions. The time required to insert the catheter was significantly shorter in the STM group, probably mainly due to a shorter guidewire insertion time. The degree of IJV collapse during advancement of the needle was much lower in the STM group. CONCLUSIONS:STM facilitates IJV catheterization in infants and neonates weighing <5 kg by enlarging the IJV and preventing vein collapse.

Vagal nerve activity contributes to improve the efficiency of pulmonary gas exchange in hypoxic humans

The aim of this study was to test our hypothesis that both phasic cardiac vagal activity and tonic pulmonary vagal activity, estimated as respiratory sinus arrhythmia (RSA) and anatomical dead space volume, respectively, contribute to improve the efficiency of pulmonary gas exchange in humans. We examined the effect of blocking vagal nerve activity with atropine on pulmonary gas exchange. Ten healthy volunteers inhaled hypoxic gas with constant tidal volume and respiratory frequency through a respiratory circuit with a respiratory analyser. Arterial partial pressure of O2 (P u2009aOu20092 ) and arterial oxygen saturation (S u2009pOu20092 ) were measured, and alveolar‐to‐arterial P u2009Ou20092 difference (D u2009A−aOu20092 ) was calculated. Anatomical dead space (VD,an), alveolar dead space (VD,alv) and the ratio of physiological dead space to tidal volume (VD,phys/VT) were measured. Electrocardiogram was recorded, and the amplitude of R–R interval variability in the high‐frequency component (RRIHF) was utilized as an index of RSA magnitude. These parameters of pulmonary function were measured before and after administration of atropine (0.02 mg kg−1). Decreased RRIHF (P < 0.01) was accompanied by decreases in P u2009aOu20092 and S u2009pOu20092 (P < 0.05 and P < 0.01, respectively) and an increase in D u2009A−aOu20092 (P < 0.05). Anatomical dead space, VD,alv and VD,phys/VT increased (P < 0.01, P < 0.05 and P < 0.01, respectively) after atropine administration. The blockade of the vagal nerve with atropine resulted in an increase in VD,an and VD,alv and a deterioration of pulmonary oxygenation, accompanied by attenuation of RSA. Our findings suggest that both phasic cardiac and tonic pulmonary vagal nerve activity contribute to improve the efficiency of pulmonary gas exchange in hypoxic conscious humans.

Severe hyponatremia occurring after surgical stress in a patient with mitochondrial disease

A 53-year-old man with mitochondrial disease underwent gastrectomy because of gastric cancer. Three days after the surgery, he developed severe hyponatremia (Na, 106 mmol·l−1) together with hypovolemic shock and lactic acidosis. Despite the hyponatremia, his urine sodium concentration was high, suggesting renal salt wasting. Although mitochondrial diseases are not common and hyponatremia in patients with these diseases is not well known, clinicians should pay close attention to serum sodium levels and maintain them properly.

The effects of carbon monoxide on respiratory chemoreflexes in humans.

As protection against low-oxygen and high-carbon-dioxide environments, the respiratory chemoreceptors reflexly increase breathing. Since CO is also frequently present in such environments, it is important to know whether CO affects the respiratory chemoreflexes responsiveness. Although the peripheral chemoreceptors fail to detect hypoxia produced by CO poisoning, whether CO affects the respiratory chemoreflex responsiveness to carbon dioxide is unknown. The responsiveness of 10 healthy male volunteers were assessed before and after inhalation of approximately 1200 ppm CO in air using two iso-oxic rebreathing tests; hypoxic, to emphasize the peripheral chemoreflex, and hyperoxic, to emphasize the central chemoreflex. Although mean (SEM) COHb values of 10.2 (0.2)% were achieved, no statistically significant effects of CO were observed. The average differences between pre- and post-CO values for ventilation response threshold and sensitivity were -0.5 (0.9) mmHg and 0.8 (0.3) L/min/mmHg, respectively, for hyperoxia, and 0.7 (1.1) mmHg and 1.2 (0.8) L/min/mmHg, respectively, for hypoxia. The 95% confidence intervals for the effect of CO were small. We conclude that environments with low levels of CO do not have a clinically significant effect acutely on either the central or the peripheral chemoreflex responsiveness to carbon dioxide.

Failure of the Airway Scope to Visualize the Glottis: Two Case Reports

The AirWay Scope® (AWS, Hoya-Pentax, Tokyo, Japan) is a video laryngoscope for tracheal intubation that provides an excellent view of the glottis without requiring alignment of the oral, pharyngeal, and laryngeal axes through the use of an anatomically curved blade (PBlade®). It has been demonstrated that the AWS can achieve tracheal intubation with a high success rate in patients with difficult intubation [1]. It has also been demonstrated that the AWS is useful for difficult intubation with restricted cervical movement [2,3], and requires less extension of the cervical spine [4,5,6]. However, we encountered two cases of difficult airways with severely impaired cervical movement, in which an AWS could not visualize the patients’ glottises.

Tidal volume and airway pressure under percutaneous transtracheal ventilation without a jet ventilator: comparison of high-flow oxygen ventilation and manual ventilation in complete and incomplete upper airway obstruction models

AbstractPurposenPercutaneous transtracheal ventilation (PTV) can be life-saving in a cannot ventilate, cannot intubate situation. The aim of this study was to investigate the efficacy of PTV by measuring tidal volumes (VTs) and airway pressure (Paw) in high-flow oxygen ventilation and manual ventilation using a model lung.MethodsWe examined 14G, 16G, 18G, and 20G intravenous catheters and minitracheotomy catheters. In high-flow oxygen ventilation, the flow was set to 10xa0L/min, while the inspiratory:expiratory phases (I:E) were 1u2009s:4u2009s in the complete upper airway obstruction model and 1u2009s:1xa0s in the incomplete obstruction model. In manual ventilation, I:E were 2u2009s:4xa0s in the complete obstruction model and 2u2009s:3xa0s in the incomplete obstruction model. We ventilated through each catheter for 2xa0min and measured VT and Paw.ResultsIn high-flow ventilation, the average VTs were approximately 150xa0ml and <100xa0ml with 14G catheters in complete and incomplete upper airway obstruction, respectively. The VTs obtained were reduced when the bore size was decreased. In manual ventilation, the average VTs were over 300xa0ml and approximately 260xa0ml with 14G catheters in complete and incomplete upper airway obstruction, respectively. In high-flow ventilation, the airway pressure tended to be higher. The minitracheotomy catheters produced over 800xa0ml of VT and created almost no positive end-expiratory pressure.ConclusionsHigh-flow ventilation tends to result in higher airway pressure despite a smaller VT, which is probably due to a PEEP effect caused by high flow.

Continuous positive airway pressure applied through a bronchial blocker as a treatment for hypoxemia due to stenosis of the left main bronchus.

success of an anticoagulatory therapy, as during clopidogrel therapy, and reflects the success of platelet activation during an anticoagulatory therapy. Therefore we were wondering whether the authors think that VASP phosphorylation could be a useful monitor in their experimental system, and whether the monitoring the extent of VASP phosphorylation could be a valuable tool to monitor the clinical effectiveness if an inhaled nitric oxide therapy.