Katsuyuki Miyasaka

A canine study of cold water drowning in fresh versus salt water.

OBJECTIVE To compare the pathophysiologic changes occurring during drowning in cold fresh water and cold salt water with reference to viability. DESIGN Randomized, prospective, controlled submersion experiments in two contrasting cold liquids. SETTING A laboratory at a large university-affiliated medical institution. SUBJECTS Thirteen healthy, anesthetized mongrel dogs. Three dogs served as controls and were immersed but not submerged. The remainder were submerged in cold fresh water or cold salt water (4 degrees C). INTERVENTIONS Catheters were placed in the femoral artery, right carotid artery and right internal jugular vein. Electrocardiogram, pneumogram, and rectal temperatures were measured continuously during submersion/immersion. MEASUREMENTS AND MAIN RESULTS Cold water submersion with drowning produced a large initial decrease in carotid artery temperature (approximately 7.5 degrees C in the first 2 mins) compared with a minor decrease (approximately 0.8 degrees C with immersion). No significant differences were noted in the rate of decrease of temperature between drowning in fresh water and salt water. During cold fresh water drowning, aspiration produced gross hemodilution with an average increase in body weight of 16.5%. Hematocrit values, serum sodium concentrations, and osmolality decreased while serum potassium concentrations, catecholamines, and free hemoglobin increased. All measured biochemical data (except PaO2) remained at viable levels. By contrast, during cold salt water drowning, average body weight increased by only 6%, with hemoconcentration and a shrinkage of vascular volume. Hematocrit and hemoglobin values increased by 30%, but initial plasma free hemoglobin values remained unchanged. Serum sodium concentrations, osmolality, and potassium concentrations increased rapidly to critical levels. CONCLUSIONS On submersion in cold water, all of the experimental animals developed tachypnea immediately, followed by aspiration with predictable effects. The biochemical and pathophysiologic changes in cold water drowning approximated those changes reported for warm water drowning for both fresh and salt water with one exception and continued aspiration of cold water produced extremely rapid core cooling as long as the circulation remained intact. This process of acute submersion hypothermia may protect the brain temporarily from lethal damage, as reported in cases of cold fresh water drowning. Concentrations of circulating catecholamines increased exponentially in both groups of test animals. Clinically, their acute effects on the circulation, compounded by significant hypothermia and extreme anoxia, must hamper the detection of residual circulation at rescue and may play a role in sudden death from cold water in the absence of drowning.

Multiwavelength Pulse Oximetry: Theory for the Future

BACKGROUND:As the use of pulse oximeters increases, the needs for higher performance and wider applicability of pulse oximetry have increased. To realize the full potential of pulse oximetry, it is indispensable to increase the number of optical wavelengths. To develop a multiwavelength oximetry system, a physical theory of pulse oximetry must be constructed. In addition, a theory for quantitative measurement of optical absorption in an optical scatterer, such as in living tissue, remains a difficult theoretical and practical aspect of this problem. METHODS:We adopted Schuster’s theory of radiation through a foggy atmosphere for a basis of theory of pulse oximetry. We considered three factors affecting pulse oximetry: the optics, the tissue, and the venous blood. RESULTS:We derived a physical theoretical formula of pulse oximetry. The theory was confirmed with a full SO2 range experiment. Based on the theory, the three-wavelength method eliminated the effect of tissue and improved the accuracy of Spo2. The five-wavelength method eliminated the effect of venous blood and improved motion artifact elimination. CONCLUSIONS:Our theory of multiwavelength pulse oximetry can be expected to be useful for solving almost all problems in pulse oximetry such as accuracy, motion artifact, low-pulse amplitude, response delay, and errors using reflection oximetry which will expand the application of pulse oximetry. Our theory is probably a rare case of success in solving the difficult problem of quantifying optical density of a substance embedded in an optically scattering medium.

Complications of radial artery lines in the paediatric patient

RésuméLes auteurs ont étudié de fa9on prospective les complications survenant après canulation de 1’artère radiale chez 47 enfants. Ils ont noté une incidence élevée de complications cutanées — 34 pour cent des cas de mineures à modérées — sauf pour un cas de nécrose cutanée après canulation par dissection, et un taux é1evé d’obstruction de 1’artère (51 pour cent des cas). Les artères se sont éventuellement toutes recanalisées dans un court délai. Les facteurs favorisant l’obstruction de 1’artère étaient:a)l’âge des enfants (66 pour cent d’obstruction chez les enfants de moins de 5 ans et 34 pour cent chez ceux de plus de 5 ans).b)latechnique de canulation (70 pour cent d’obstruction suivant une technique avec dissection et 31 pour cent par voie percutanée ).c)ladurée de canulation (71 pour cent d’obstruction suivant une canulation de plus de 4 jours et 43 pour cent si moins de 4 jours ). Les auteurs proposent les précautions suivantes: vérification des arcades palmaires avant la canulation, non canulation en présence de mauvaise vascularisation de la main par traumatisme ou par maladie, enlèvement immédiat-de la canule en cas d’apparition de phénomènes ischémiques passagers, et embolectomie immédiate en cas d’isoémie permanente; ils concluent que si ces précautions sont prises, cette forme de monitoring est parfaitement justifiée malgré une incidence élevée de complications mineures.

Manifestation of Mirror Syndrome after Fetoscopic Laser Photocoagulation in Severe Twin-Twin Transfusion Syndrome

Mirror syndrome is a preeclampsia-like disease first described in a case of severe hydrops fetalis caused by rhesus isoimmunization, later reported in some cases of nonimmunological fetal hydrops. Twin-twin transfusion syndrome (TTTS) is a severe complication associated with monochorionic pregnancies, in particular, severe TTTS with one hydropic fetus leading to a poor prognosis. We report here a case of mirror syndrome that occurred after selective fetoscopic laser photocoagulation in severe TTTS at 24 weeks’ gestation.

Flow velocity profile of the pulmonary artery measured by the continuous cardiac output monitoring catheter

The KATS catheter (continuous arterial thermodeprivation system catheter) measures the blood flow velocity of the pulmonary artery (PA) by thermodeprivation which enables continuous determination of cardiac output. The accuracy of this system may depend on the degree of uniformity of flow velocity in the PA, because small movements of the catheter within the PA are inevitable with a beating heart. We evaluated the flow velocity profile of the PA in seven anaesthetized open-chest dogs to assess these potential errors. A custom-made stiff catheter, at the tip of which was incorporated the flow velocity sensor of the KATS catheter, was used to penetrate the main PA in the short axis direction (perpendicular to flow direction) or the long axis direction (along flow direction). The stiff catheter was moved in increments of 2.5 mm, and flow velocity was recorded. The wall-to-wall distance of the PA along each direction was divided into five sections (S1 to S5 for the short axis, and L1 to L5 for the long axis). Flow velocity data for each section were averaged and presented as relative values against the control mid-point velocity. Along the short axis, flow velocity was 0.41 ± 0.20 (SD), 1.00 ± 0.10, 1.03 ± 0.10, 1.08 ± 0.13 and 0.49 ± 0.26 from S1 to S5, i.e., lower in S1 and S5 which were close to the vascular walls (P < 0.05) but uniform in other areas. Along the long axis, flow velocity was 0.28 ± 0.28, 0.88 ± 0.09, 0.94 ± 0.08, 1.06 ± 0.25 and 1.28 ± 0.50 from L1 to L5. Thus, flow velocity was lower in L1 which was close to the bifurcation (P < 0.05), slightly higher in L5 close to the pulmonary valve, but uniform in other areas. These results suggest that the profile of blood flow velocity is relatively uniform within the main PA except in areas close to the vessel walls or valve. We conclude that movement of the catheter within the vessel would not substantially influence the accuracy of the KATS catheter system as long as the flow velocity sensor of the catheter stays within the main PA.RésuméLa sonde KATS (Continuous Arterial Thermodeprivation Systems), en calculant par déperdition thermique la vitesse de l’écoulement sanguin dans l’artère pulmonaire (AP), mesure le débitcardiaque. La précision du système peut dépendre de la Constance de la vélocité sanguine dans l’AP, les battements cardiaques rendant inévitables de petits mouvements de la sonde. Pour évaluer cette source potentielle d’erreurs, nous avons mesuré le profil de la vélocité de l’écoulement sanguin sur sept chiens anesthésiés, à thorax ouvert. Nous avons intégré le senseur de vélocité de courant d’une sonde KATS à un cathéter rigide, créé sur mesure, dans le but de pénétrer l’AP principale perpendiculairement à la direction du flux sanguin (axe court) ou parallèlement à sa direction (axe long). Le cathéter rigide a été avancé par paliers de 2,5 mm et la vélocité du flux mesurée. Nous avons établi la moyenne les données et les avons présentées comme des valeurs relatives en regard d’un point-contrôle central. Sur l’axe court, la vélocité du courant a été de 0,41 ± 0,20 (SD), de 1,00 ± 0,01, de 1,03 ±0,01, de 1,08 ± 0,13 et de 0,49 ± 0,26, des points S1 à S5 respectivement; done plus basse à S1 et S5 qui sont les points les plus rapprochés des parois vasculaires (P < 0,05) mais uniforme dans les autres zones. Parallèlement, à l’axe long, la vélocité #x2019;était de 0,28 ± 0,28, de 0,88 ± 0,09, de 0,94 ± 0,08, de 1,06 ± 0,25, et de 1,28 ± 0,50 de L1 à L5 La vélocité du courant était done moindre à L1 lequel est situé près de la bifurcation (P < 0,05), légèrement plus grande a L5 pres de la valve pulmonaire, mais uniforme dans les autres zones. Ces résultats suggèrement que le profil de la vélocité de l’écoulement sanguin est relativement uniforme dans l’AP principale à l’exception des points situés à la proximité des parois et de la valve. Nous concluons que les mouvements de sonde dans un vaisseau ne devraient pas influencer de façon appréciable la précision du système de sondes KATS aussi longtemps que le senseur de vélocité reste dans l’artère pulmonaire principale.

Localized Pulmonary Edema in the Middle and Inferior Lobes of the Right Lung after One-lung Ventilation for Minimally Invasive Mitral Valve Surgery

Fiberoptic bronchoscopy revealed an ectopic tracheal bronchus to the right upper lobe arising 3 cm above the carina. An endobronchial blocker (COOPDECH™, Osaka, Japan) was positioned in the proximal right intermediate bronchus, blocking the middle and inferior lobes. Although the right upper lobe was ventilated, it did not obstruct the surgical field via a right anterior thoracotomy. The patient was ventilated using pressure-control ventilation with inspiratory pressure 20 cm H2O, positive end-expiratory pressure (PEEP) 6 cm H2O, and tidal volume 500 mL at an FIO2 1.0 after collapse of the right middle and lower lobes. The femoral artery was cannulated with a 20-Fr arterial cannula and the femoral vein with a 28-Fr venous cannula positioned into the right atrium with the tip in the superior vena cava to establish CPB. An antegrade cardioplegia cannula was inserted into the ascending aorta with a flexible cross-clamp subsequently applied. The heart was arrested initially by using antegrade cold blood cardioplegia. Myocardial protection was provided using mild systemic hypothermia (341C), and antegrade cold blood cardioplegia was given throughout the procedure at 30-minute intervals.

Finite Element Modeling of a Mainstream Capnometer System for Non-Intubated Pediatric Patients Requiring Oxygen Administration

Capnometry is the standard of care to measure the amount of carbon dioxide in the proximal airway, detect apnea, tracheal tube dislodgement, and effectiveness of ventilation during invasive mechanical ventilation in critically ill infants, children and adults [1]. Capnometry is not yet standard practice for non-invasively supported or ventilated patients, due to dead space ventilation, inspiratory gas washout, gas entrainment, and potential for rebreathing of gas. Potential capnometry use in non-intubated patients could identify impending respiratory failure, obstructed airways, and improve the safety and effectiveness of non-invasive support for infants and children [2].Copyright

A TALE OF TWO CITIES: TIMING OF BRAIN IMAGING AND NEUROPHYSIOLOGIC ASSESSMENTS FOLLOWING IN-HOSPITAL PEDIATRIC CARDIAC ARREST: 226

Introduction: Neurologic imaging and physiologic studies may predict functional outcome following Cardiac Arrest(CA). Cross-cultural comparisons of neurodiagnostic assessments have not been described following pediatric in-hospital CA. Hypothesis: Post-resuscitation neurologic assessment in children rarely includes brain imaging or physiologic studies in the first 72 hours and diagnostic approach differs between cultures. Methods: Retrospective review of consecutive in-hospital pediatric CA’s(chest compressions >1 minute) at the Children’s Hospital of Philadelphia (P,3/01 to 7/03) and National Center for Child Health and Development in Tokyo(T,3/02 to 2/04) using the Pediatric Utstein CA report template. Timing of neurologic imaging(CT, MRI scans), and physiologic studies(EEG, BAER) were compared. Analysis by two-tailed Fisher’s exact test with alpha=0.05. Results: Of 122 CA, 64(52%) survived >24 hours: 51/104(49%)P and 13/18(72%)T [p=ns]. Within 24 hours after CA, 25/51(49%)P and 11/13(85%)T were comatose with GCS <8, and 19/51(37%)P and 4/13(31%)T received iatrogenic paralysis; but only 31%(P=T) had any imaging or physiologic studies. Within 72 hours 8%P vs 15%T had both imaging and physiologic studies, 11%P vs 8%T had imaging only, 24%P vs 15%T had physiologic studies only, and 59%P vs 62%T had no studies(p=ns). At 72 hours after CA, 13/49(27%)P and 7/11(64%)T were iatrogenically paralyzed(p<0.05), but only 41%P and 38%T had imaging or physiologic studies(p=ns). 47/64(73%) had either imaging or physiologic study prior to discharge: 36/51(71%)P vs 11/13(85%)T,[p=ns]. Conclusions: In two large international children’s hospitals, early iatrogenic masking of the neurologic exam with paralytics is common <72 hours post-CA, but imaging and physiologic studies are obtained in only 40% of CA survivors <72 hours. Cultural differences in approach to post-CA management suggest that the timing and intensity of neurologic imaging and neurophysiologic assessment may be important.

The Pressure Change Inside and Outside of the Trachea during the Respiratory Cycle

従来の呼吸生理学の上では気管壁は吸気時に拡張するとされる。ところが実際の胸腔内中枢気道狭窄性疾患の人工呼吸管理では吸気性呼吸困難を呈する症例がみられる。われわれは気管壁の動きが気管内外差圧に支配されることに着目し, 自発呼吸下の気管内圧, 気管周囲圧および胸腔内圧を気管内挿管されたイヌにおいて同時測定した。結果として, 気管壁は呼気時に拡張方向, 吸気時に狭窄方向の力を受けることが示された。また気管周囲圧は胸腔内圧とほぼ平行に動き, 気管内圧は呼吸流量と同じ時相で変動した。今回の結果は古典的呼吸生理学から理論的に考えられる気管内外差圧の動きとは逆であった〇また, 今回の現象は, 最大吸気流量が中枢気道性疾患に於て特異的に低下するとの以前のわれわれの臨床報告を裏付けるものである。