Yukako Obata

Vasopressin and epinephrine are equally effective for CPR in a rat asphyxia model

Epinephrine has been administered as a drug essential for cardiopulmonary resuscitation (CPR). Recently, vasopressin has been reported to be more effective than epinephrine for CPR in a ventricular fibrillation (VF) model. As a different myocardial pathology is speculated to exist between the VF model and the asphyxia model, we investigated whether vasopressin is also effective in a rat asphyxia model. Twenty-one Sprague-Dawley male rats were divided into three groups: vasopressin 0.8 U/kg (Vaso-Gr), epinephrine 0.05 mg/kg (Epi-Gr), and saline same volume as the other two drugs (Sal-Gr). Five minutes after suffocation induced by obstruction of the tracheal tube, CPR was performed using each drug. Although only one animal survived (17%) in the Sal-Gr, 6/7 (85%) survived in both Vaso-Gr and Epi-Gr (P<0.01). Vasopressin is as effective as epinephrine for CPR in asphyxia-induced rats.

Vasopressin with delayed combination of nitroglycerin increases survival rate in asphyxia rat model

Recently, vasopressin has been reported as a more effective drug than epinephrine (adrenaline) for cardiopulmonary resuscitation (CPR). However, vasopressin decreases myocardial blood flow (MBF) because of its strong vasoconstriction, to maintain better coronary perfusion pressure (CPP) compared with epinephrine. Nitroglycerin is well known to be able to maintain MBF and increase survival rate. In a VF model, vasopressin combined with nitroglycerin maintained CPP; however, low survival rates were observed compared with vasopressin alone. We investigated the effectiveness of the delayed use of nitroglycerin combined with vasopressin in a severe asphyxia model. Fourteen Sprague-Dawley male rats were divided into two groups: vasopressin 0.8 U/kg alone (V-Gr.), and nitroglycerin 0.3 microg/kg 45 s after the administration of 0.8 U/kg vasopressin (VN-Gr.). Six min after asphyxia induced by obstructing the tracheal tube, CPR was performed in two ways. Three animals resuscitated in the V-Gr. (42%) and six/seven (84%) in the VN-Gr. (P<0.05). In the 6 min of asphyxia rat model, vasopressin combined with delayed nitroglycerin is more effective than vasopressin alone.

Syringe pump displacement alters line internal pressure and flow.

PurposeIt has been reported that the actual flow from a syringe pump changes due to vertical movement of the pumpin vitro, but a direct study of thein vivo effects of fluid delivery irregularities caused by vertical pump displacement has not been performed. The aim of this study was to assess the influence of positional changes of the syringe pump on the internal pressure (IP) and flow from the circuit, and to examine blood pressure changes caused by pump movement in animals with or without hemorrhagic shock.MethodsTo simulate clinical conditions, we used a rabbit model. We first measured the changes in line IP and flow from the syringe pump after moving the pump 50 cm vertically upwards or downwards. With the same animal, we then recorded the blood pressure changes under these conditions during norepinephrine (NE) infusion, using a rabbit hemorrhagic shock (HS) model.ResultsFollowing downward movement of the syringe pump, the IP increased by 37.5 ± 4.0 mmHg and IP decreased by 37.3 ± 3.1 mmHg following upward movement of the syringe pump. In the rabbit HS model, movement downwards decreased systolic blood pressure (SBP) by -17 ± 6.9% (P < 0.001), while upward movement raised SBP by 45.7 ± 21.5% (P < 0.001) from baseline values. Conclusions: Vertical displacement of the syringe pump alters the flow due to a change of line I P, and blood pressure can be affected by pump movement during NE infusion.RésuméObjectifOn sait que le débit effectif dans la pompe à perfusion change avec le déplacement vertical de la pompe in vitro, mais aucune étude directe n’a été réalisée sur les effets in vivo de ľirrégularité du débit causée par le déplacement vertical de la pompe. Nous voulions évaluer ľinfluence des changements de position de la pompe à perfusion sur la pression interne (PI) et le débit provenant du circuit, et vérifier les changements de tension artérielle causés par le déplacement de la pompe chez des animaux soumis ou non à un choc hémorragique.MéthodePour simuler les conditions cliniques, nous avons utilisé un modèle expérimental chez un lapin. Nous avons ďabord mesuré les changements de PI, dans le cathéter, et de débit provenant de la pompe à perfusion après avoir déplacé la pompe de 50 cm vers le haut ou vers le bas. Nous avons ensuite enregistré les modifications de tension artérielle dans ces conditions pendant la perfusion de norépinéphrine (NE) en utilisant un modèle de choc hémorragique (CH).RésultatsAprès le déplacement de la pompe vers le bas, la PI a augmenté de 37,5 ± 4,0 mmHg, mais la PI a baissé de 37,3 ± 3,1 mmHg après le déplacement vers le haut. Dans le cas du modèle de CH chez le lapin, le déplacement vers le bas a fait baisser la tension artérielle systolique (TAS) de -17 ± 6,9 % (P < 0,001), tandis que le déplacement vers le haut a fait monter la TAS de 45,7 ± 21,5 % (P< 0,001) par rapport aux valeurs de départ.ConclusionLe déplacement vertical de la pompe à perfusion modifie le débit en raison ďun changement de la PI du cathéter. La tension artérielle peut être modifiée par le mouvement de la pompe pendant la perfusion de NE.

Preemptive analgesia by preoperative administration of nonsteroidal anti-inflammatory drugs.

Recently, Gramke et al. [4] demonstrated that preoperative sublingual piroxicam was more effective than postoperative administration. Other NSAIDs, including intravenous ketorolac [5] and fl urbiprofen [2,6], have also been reported to provide preemptive analgesia. In our study [2], we confi rmed that preemptive and long-lasting analgesia derived from fl urbiprofen was independent of the residual drug concentration. There is room for discussion about the effect of preemptive analgesia; however, available data suggest that anesthesiologists should apply multimodal analgesic techniques, including NSAIDs, to achieve the benefi ts of preemptive analgesia [7].

The effect of aging on dopamine release and metabolism during sevoflurane anesthesia in rat striatum: An in vivo microdialysis study

We have previously reported that halothane anesthesia increases extracellular concentrations of dopamine (DA) metabolites in rat striatum using in vivo microdialysis techniques. Aging induces many changes in the brain, including neurotransmission. However, the relationship between aging and changes in neurotransmitter release during inhalational anesthesia has not been fully investigated. The aim of the present investigation was to evaluate the effect of sevoflurane on methamphetamine (MAPT)-induced DA release and metabolism in young and middle-aged rats. Male Sprague-Dawley rats were implanted with a microdialysis probe into the right striatum. The probe was perfused with a modified Ringers solution and 40μl of dialysate was directly injected to an HPLC every 20min. Rats were administered saline, the same volume of 2mgkg(-1) MAPT intraperitoneally, or 5μM MAPT locally perfused. After treatments, the rats were anesthetized with 1% or 3% sevoflurane for 1h. Sevoflurane anesthesia significantly increased the extracellular concentration of DA only in middle-aged rats (52-weeks-old). In young rats (8-weeks-old), sevoflurane significantly enhanced MAPT-induced DA when administered both intraperitoneally and perfused locally, whereas no significant additive interaction was found in middle-aged rats. These results suggest that aging changes DA release and metabolism in rat brains primarily by decreasing the DA transporter.

Radial artery cannulation using the Insyte-A holding the device in cigarette-style

Recently, a guidewire-assisted radial artery cannulation technique was introduced, and this method is becoming popular [2]. The Insyte-A (BD Medical Japan, Tokyo, Japan) is a newly developed instrument for arterial catheter insertion [3]. The guidewire is integrated in a freely moving plunger and is easily introduced into the lumen of the vessel. Although the device has room for further development [4], it has led to an improved success rate for cannulation. Usually, a physician would puncture an artery using the nondominant hand for holding the subject while searching for pulsation, and using the dominant hand for grasping the needle in a pen-holding style and penetrating the skin. When the top of the needle reaches the artery, regurgitation of blood is observed, and the physician keeps the dominant hand still and attempts to insert the guidewire with nondominant hand which is holding the subject until immediately before the insertion. This traditional technique is not stable and may disturb the establishment of the relationship between the inner needle and the lumen of the artery. Therefore, we are now applying the “cigarette-holding method” for artery cannulation, using the Insyte-A. The device is held with the index and middle fi ngers, just like holding cigarette (Fig. 1). The thumb is prepared for advancing the guidewire freely. When puncture is achieved, the guidewire is introduced into the vessel lumen promptly, without any other Radial artery cannulation using the Insyte-A holding the device in cigarette-style

A recommended solution for avoiding coring of a rubber stopper.

In Response: Drs. Lohser and Brodsky raise the measurement of left mainstem bronchial diameter as an indicator of proper sizing for left-sided doublelumen tubes (DLT), and suggest that use of this technique in our recent study may have yielded different results. While we don’t question the mathematical formulas, none of the clinicians involved in the study practice this method despite over 80 years of cumulative experience successfully placing DLT in an institution where 2000 thoracic procedures are performed each year. Accordingly, our work addressed the prevalent practice at our institution of sizing DLT by height and/or gender. Although the participating anesthesiologists were all initially trained to use conventional methods at a time when fiberoptic bronchoscopy was not readily available, the strength of our study design is that we compared outcomes in a single clinical setting between anesthesiologists whose practice now differs. Our data showed that in regard to intraoperative end-points reflecting the adequacy of lung collapse and preservation of oxygenation, both our “conventional” approach and intentional downsizing are comparable. While we appreciate the interpretation by Drs. Lohser and Brodsky that our observed “failure to isolate” temporarily may well have been due to undersized DLT, we maintain our stated conclusion that malposition was responsible. With respect to the rare event of DLT causing airway damage, the authors cite their own early data indicating that rupture in particular is most frequently associated with small DLT, perhaps due to the need for relative cuff hyperinflation. While we included this citation in our manuscript, we also included references indicating the possibility of trauma from either small or large DLT, a risk also previously noted by Brodsky and Lemmens and cited in our paper. Furthermore, despite use of down-sized DLT we rarely found that more than 3 mL was required to provide an adequate seal. The authors further point to the theoretical increase in auto-PEEP due to downsizing of DLT. While experimental studies have clearly shown differences in the gas flow characteristics between large and small DLT, neither results of the our study nor our extensive clinical experience have given any indication that the 0.6 mm difference between a 35 and 39 FR internal diameter has had any deleterious effects in our patient population. Indeed, our reported incidence of intraoperative hypoxemia and recently published incidence of acute lung injury in 1,428 patients undergoing lung resection are low and consistent with the literature.

Radial artery cannulation decreases the distal arterial blood flow measured by power Doppler ultrasound.

Radial arterial cannulation is a popular technique for continuous hemodynamic monitoring in an area of anesthesia and intensive care. Although the risk for invasive monitoring is considerable, there is scarce information about the change in blood flow of cannulated vessel after the catheterization. In the current investigation, we evaluated the change in the cannulated arterial blood flow. Six volunteers (study 1) and eight post-surgical patients (study 2) were enrolled into the studies. In the study 1, the both side of diameter of radial artery (RA), ulnar artery (UA) and dorsal branch of radial artery (DBRA) of participants were measured using power Doppler ultrasound (PDU) with or without proximal oppression. In the study 2, the diameter of RA, UA and DBRA of the both intact and cannulated side were compared. Study 1: The diameter of RA was 3.4 (0.52) [mean (SD)] mm and the proximal oppression significantly decreased the diameter to 1.8 (0.59) mm. The diameter of DBRA measured by PDU also decreased 2.0 (0.60)–1.3 (0.59) mm. Study 2: There was no difference between the diameters of right and left RA, however, the UA was larger [3.4 (0.60) vs. 2.8 (0.83) mm] and the DBRA was narrower [1.4 (0.43) vs. 2.0 (0.47) mm] in the cannulated side. The diameters of DBRA were different between the intact and cannulated side in the patients. Although there is no information of relationships between cause of severe complication and decreased flow, significant reduction of blood flow should be concerned.

Radial artery cannulation using the Insyte-A device with ultrasound assistance

radial artery cannulation was recently emphasized [2–5], the conventional arterial cannulation method limits the implementation of ultrasound imaging, because the physician has to insert the outer cannula into the artery using the unskillful hand after releasing the ultrasound probe. The effect of this supplemental movement on the critical procedure may be related to cannulation failure. To overcome this problem, we apply ultrasound imaging with the probe being handled with the unskillful hand, using the cigarette-holding method with the Insyte A device (Fig. 1). Using this method, the anesthesiologist is able to puncture the artery with the image guidance, and, once the guidewire is introduced into the artery only with the thumb, the ultrasound probe can be released without diffi culty, because the connection between the artery and guidewire is established and confi rmed. After the releasing action, the outer cannula can be easily advanced with the unskillful hand. Until now, we have carried out more than 30 approaches; only 2 failed, because of diffi culty owing to re-cannulation. This combination method of using ultrasound assistance for radial artery cannulation with the Insyte-A device has advantages for cannulation. We were able to administer a suffi cient amount of local anesthetic into the subcutaneous space of the puncture site. Also, the swelling caused by fl uid infusion did not disturb the ultrasound imaging. Especially for cannulation in an awake patient, this would be of great value. Another advantage is that we can approach the radial artery at a more proximal site, because the physician is not required to detect Radial artery cannulation using the Insyte-A device with ultrasound assistance

Hemothorax resulting from venous tearing by a catheter

malpositioning of the guidewire would be followed by venous tearing with a large-bore dilator or a catheter. We have no clinical evidence concerning the relationship between the shape of a guidewire and the safety of vein catheterization [5]. The size of the puncturing needle used with an angle-tip guidewire is usually smaller than that of the puncturing needles used with J-tip guidewires. However, like Innami et al. [1], we also recommend not to use an angle-tip guidewire, from the view point of the possible migration of such guidewires.