Reservoir Bag Research Articles

General Anesthesia in Geriatric Dogs with Propofol-Isoflurane, PropofolSevoflurane, Alphaxalone-Isoflurane, Alphaxalone-Sevoflurane and Their Comparison of Biochemical, Hemodynamic and Cardiopulmonary Effects

Background: Geriatric is defined as the life-cycle in which the physical state, organ functions, sensory functions, mental function and immunity progressively regress. Aging causes progressive and irreversible changes in the functional capacities of organ systems, which in turn alter the response to stress and anesthetic drugs. Propofol is an anesthetic agent with sedative and hypnotic effects. Anesthesia induction with propofol is fast and smooth. Alphaxalone (3α-hydroxy-5α-pregnane11,20-dione) is a central nervous system depressant in the form of synthetic neuroactive steroids. This allows anesthesia and muscle relaxation by increasing the inhibition of gamma amino butyric acid type A (GABA) receptors. The aim of this study is to compare effects of propofol-isoflurane and propofol-sevoflurane with relatively a new anesthetic combination alphaxalone-isoflurane and alphaxalone-sevoflurane on hematological, biochemical and physiological parameters.Materials, Methods & Results: Dogs were randomly divided into 4 groups and anesthesia protocols were applied. After induction of anesthesia with 6 mg/kg propofol in groups 1 and 2, isoflurane anesthesia was continued in group 1 and sevoflurane in group 2. After induction of 3 mg/kg alphaxalone anesthesia in groups 3 and 4, isoflurane anesthesia was continued in group 3 whereas sevoflurane in group 4. Vena cephalica was catheterized for blood collection. At the preanesthetic period, 15, 30, 45, 60 min and 60 min after the anesthesia, complete blood counts were performed. Serum ALT, AST, urea, creatinine values were measured during preanesthesia, perianesthesia 15-30 min and 60 min after anesthesia. Cardiopulmonary parameters and reflexes were evaluated before anesthesia and recorded at perianesthetic 5, 10, 15, 30, 45, 60 min and 60 min after full recovery. Patients were monitored during anesthesia. The average age of the dogs in the study was 10.83. All of the dogs were anesthetized in a few seconds with intravenous injection of propofol or alphaxalone. During anesthesia the respiratory rate (fR) was recorded by counting the movements of the reservoir bag. A pulse oximeter was used to monitor pulse rate (fH) and haemoglobin oxygen saturation (SpO2). Body temperature was measured from rectum with a thermometer. Geriatric dogs were anesthetized for a variety of clinical reasons, concerning laparatomy (12.5%), orthopedic (7.5%), soft tissue (60%), dental (10%) and ophthalmologic surgery (10%). Duration of anesthesia was 94.44 (± 12.6) for group I, 81(± 10.54) for group II, 93.88 (± 11.6) for group III and 64.5 (± 3.97) min for group IV. Serum urea and creatinine concentrations were not significantly different in the four groups.Discussion: The mean duration of anesthesia recovery was 6.0 ± 2.0 in group 1, 4.6 ± 1.45 in group 2, 3.7 ± 1.23 in group 3 and 9.7 ± 3.09 min in group 4. In group 4 recovery was longer than other groups and statistically significant (P < 0.05). In our research, the recovery is shorter in the isoflurane treated groups than in the sevoflurane treated groups. When the effect of different groups on heart rate was examined, the difference between them was not significant. Duration and depth of the anesthesia with propofol-isoflurane, propofol-sevoflurane, alphaxalone–isoflurane and alphaxalone-sevoflurane were found to be satisfactory for surgery. Four anesthetic agents applied in geriatric dogs did not adversely affected the hematological and biochemical parameters. In conclusion anesthesia on geriatric dogs after induction of propofol and alphaxalone maintained with isoflurane or sevoflurane found to be safe. However, they did not provide analgesia in painful operations, so it would be appropriate to use analgesics in the pre or intraoperative period.

Reservoir Bag for WalkMed Infusion Pump

Reservoir Bag for WalkMed Infusion Pump

A Case of Methemoglobinemia Successfully Treated with Hyperbaric Oxygenation Monotherapy

BackgroundMethylene blue is the first-line therapy for methemoglobinemia, but it can be intermittently unavailable due to production issues. For this clinical scenario, alternative treatment options need to be explored. Hyperbaric oxygenation (HBO) is conventionally applied as an adjunctive therapy during the systemic administration of methylene blue. Currently, little is known regarding the effects of HBO monotherapy in methemoglobinemia. We report a case of methemoglobinemia that was successfully treated with HBO monotherapy. Case ReportA 41-year-old man presented to the Emergency Department with dyspnea and dizziness subsequent to smoking in a garage filled with motor vehicle exhaust gas. There were no abnormal heart or lung sounds. While administering oxygen flowing at 15 L/min via a mask with a reservoir bag, blood tests revealed high methemoglobin (MetHb) levels at 59.6%. He was treated with HBO monotherapy, and sequential tests showed that the MetHb level decreased significantly to 34.0%, 12.8%, 6.2%, and eventually, 3.5%. He was discharged with stable vital signs the next day. Why Should an Emergency Physician Be Aware of This?HBO monotherapy is an effective alternative treatment for methemoglobinemia when methylene blue is not available.

Carbon dioxide narcosis due to inappropriate oxygen delivery: a case report

BackgroundOxygen delivery to patients with chronic obstructive pulmonary disease may be challenging because of their potential hypoxic ventilatory drive. However, some oxygen delivery systems such as non-rebreathing face masks with an oxygen reservoir bag require high oxygen flow for adequate oxygenation and to avoid carbon dioxide rebreathing.Case presentationA 72-year-old Caucasian man with severe chronic obstructive pulmonary disease was admitted to the emergency department because of worsening dyspnea and an oxygen saturation of 81% measured by pulse oximetry. Oxygen was administered using a non-rebreathing mask with an oxygen reservoir bag attached. For fear of removing the hypoxic stimulus to respiration the oxygen flow was inappropriately limited to 4L/minute. The patient developed carbon dioxide narcosis and had to be intubated and mechanically ventilated.ConclusionsNon-rebreathing masks with oxygen reservoir bags must be fed with an oxygen flow exceeding the patient’s minute ventilation (>6–10 L/minute.). If not, the amount of oxygen delivered will be too small to effectively increase the arterial oxygen saturation. Moreover, the risk of carbon dioxide rebreathing dramatically increases if the flow of oxygen to a non-rebreathing mask is lower than the minute ventilation, especially in patients with chronic obstructive pulmonary disease and low tidal volumes. Non-rebreathing masks (with oxygen reservoir bags) must be used cautiously by experienced medical staff and with an appropriately high oxygen flow of 10–15 L/minute. Nevertheless, arterial blood gases must be analyzed regularly for early detection of a rise in partial pressure of carbon dioxide in arterial blood in patients with chronic obstructive pulmonary disease and a hypoxic ventilatory drive. These patients are more safely managed using a nasal cannula with an oxygen flow of 1–2L/minute or a simple face mask with an oxygen flow of 5L/minute.

Funkcije anestezijskega dihalnega balona v dihalnem sistemu

Tis article addresses the different functions of anesthesia reservoir bag in a breathing system. A main purpose of the contribution was to explain complex interaction between the reservoir bag and fresh gas flow during mechanical ventilation. The anesthesia reservoir bag is a collapsible gas container which is an essential component of most breathing systems. The anesthesia reservoir bag permits manual ventilation and acts as a visual or tactile indicator of spontaneous ventilation. The bag was excluded from traditional breathing system when the ventilator was in use. Discrepancies between the set and actual tidal volume can occur. However, on some anesthesia workstation systems, such as the Dräger Primus, the reservoir bag is an integral part of the breathing system during mechanical ventilation, where it serves as a reservoir for oxygen and anaesthetic gases. In mechanically ventilated patients, gases enter the bag from the fresh gas flow during inspiration, when the decoupling valve closes. The safe administration of general anesthesia requires understanding of the technological advances in highly sophisticated anesthetic equipment.

Functions of anesthesia reservoir bag in a breathing system

Tis article addresses the different functions of anesthesia reservoir bag in a breathing system. A main purpose of the contribution was to explain complex interaction between the reservoir bag and fresh gas flow during mechanical ventilation. The anesthesia reservoir bag is a collapsible gas container which is an essential component of most breathing systems. The anesthesia reservoir bag permits manual ventilation and acts as a visual or tactile indicator of spontaneous ventilation. The bag was excluded from traditional breathing system when the ventilator was in use. Discrepancies between the set and actual tidal volume can occur. However, on some anesthesia workstation systems, such as the Drager Primus, the reservoir bag is an integral part of the breathing system during mechanical ventilation, where it serves as a reservoir for oxygen and anaesthetic gases. In mechanically ventilated patients, gases enter the bag from the fresh gas flow during inspiration, when the decoupling valve closes. The safe administration of general anesthesia requires understanding of the technological advances in highly sophisticated anesthetic equipment.

In Vitro Study of Magnetic Resonance Imaging Artifacts of Anesthetic Devices

Introduction: Deep sedation or general anesthesia is usually required for Magnetic Resonance Imaging when patients cannot remain motionless in the suite. Various anesthetic devices have been used to maintain the airway and ventilate the lungs during this period but some of them produce artifacts that pose difficulties in the interpretation of images. The aim of this study was to identify the devices that produced artifacts during Magnetic Resonance Imaging.Methods: Twelve anesthetic devices were considered: oro-pharyngeal airway, naso-pharygeal airway, face mask with reservoir bag, nasal cannula, endotracheal tube, disposable Ambu Laryngeal Mask Airway, Laryngeal Mask Airway Unique, Disposable Laryngeal Tube Sonda, i-gel, Ambubag, Bain Circuit, Jackson Rees Circuit.Magnetic Resonance Imaging was performed with each device placed on the top of a phantom simulator respectively to resemble the position in vivo.Results: The artifacts with Disposable Laryngeal Tube Sonda, Laryngeal Mask Airway Unique and endotracheal tube were related to ferromagnetic material in the pilot valve were similar. No artifacts were found with oro-pharyngeal airway, naso-pharygeal airway, nasal cannula, endo-tracheal tube with pilot valve detached, face masks with reservoir bag (metal removed), Ambu bag (without Adjustable Pressure Limiting valve), i-gel , disposable Ambu Laryngeal Mask Airway, Bain Circuit and Jackson Rees Circuit.Conclusions: Anesthetic devices not containing any ferromagnetic material are recommended for use during MRI scanning to reduce artifacts.

The amazing Minivent ventilator

In the mid-1960s Dr Anthony Cohen, an anaesthetist in private practice in Johannesburg, developed the Minivent respirator in response to the lack of ventilators that existed at that time in operating theatres in both private and state hospitals. The remarkable, rugged, miniature ventilator had only four components, could fit into an anaesthetist’s pocket and required no electrical power source. The pressure generated by the distension of a reservoir bag by the flow of anaesthetic gases to the patient triggered inspiration and the switch from inspiration to expiration was controlled by a pressure-sensitive magnetically operated bobbin. The device operated as a minute volume divider. Respiratory rate was obtained by counting the clicking noise from the bobbin and, provided there was no leak, tidal volume was easily calculated by dividing the gas flow by the respiratory rate. The device was widely used in numerous countries including South Africa, the United Kingdom, Australia and Canada.

Difficult bag mask ventilation: Catheter mount cap, a cause for concern.

Sir, Use of disposable products is common in anaesthesia practice. Occasionally, aberrations can occur in this type of equipment. Failure to check equipment properly is an important factor leading to potential critical events. Proper checking of equipment before use may help prevent equipment-related morbidity and mortality, improve preventive maintenance and educate the provider about equipment.[1] Unfortunately, failure to perform a proper check before use is common.[2] A 54-year-old female patient was posted for examination under anaesthesia and a cervical biopsy in the minor operation theatre. Prior to induction of general anaesthesia, the oxygen saturation was 99%. Following induction with fentanyl and propofol, we encountered a tight bag situation while using the face mask and could not ventilate the patient. There was no chest rise and no air entry on auscultation. We increased the depth of anaesthesia, optimised mask holding and used an oral airway. On visual inspection, the anaesthesia circuit assembly appeared appropriate. The bag continued to remain tight with no chest expansion, with no obvious reason for difficult mask ventilation. Post-induction, the oxygen saturation was 98%. The mask was disconnected from the circuit to connect to a self-inflating reservoir bag for ventilation, anticipating desaturation due to the lapsed time. The patient could be ventilated easily using the self-inflating reservoir bag. Much to our surprise, we saw a red-coloured cap occluding the mask, which was completely concealed when connected to the catheter mount [Figure 1a]. The red-coloured catheter mount cap was not removed before connecting to the mask and had resulted in the complete circuit obstruction [Figure 1b]. Once recognized, the cap was removed, the patient could be ventilated easily and the anaesthesia proceeded uneventfully. Figure 1 (a) Catheter mount cap concealed in the mask, (b) complete obstruction of the mask with cap (viewed from above), (c) complete obstruction of the mask with cap (viewed from below), (d) catheter mount covered with cap The red cap covering the catheter mount connected to the mask if not noticed on time could have led to potentially dangerous consequences. This was not a manufacturing defect, and interestingly, the cap fitted perfectly well into the mask [Figure 1c]. This was not detected through the mask as it was semi-opaque. These caps may often be transparent and may not be picked up even through a transparent mask. The catheter mount with the cap [Figure 1d] was connected to the mask by a new operating room technician who was unaware of the consequences. In a busy place like the minor operation theatre with a rapid turnover, due to paucity of time, things are often hurried leading to failure to perform a proper equipment check. A visual check may well have picked up the fault.[3] On doing a root cause analysis, we discovered that the circuit had been checked by the provider; however, the disposable catheter mount was attached in the circuit and fitted to the mask by the technician just prior to induction of anaesthesia and the cap thus went unnoticed. The anesthesia apparatus check-out recommendations[4] clearly states that though the technician may have a role in checking the equipment, the ultimate responsibility for ensuring that the equipment functions properly lies with the anaesthesia provider. Thus, failure to check the complete breathing system assembly may account for serious negligence on the part of the anaesthesia provider. This case reaffirms the importance of a complete cockpit drill before conducting anaesthesia. Financial support and sponsorship We have no financial support and sponsorship Conflicts of interest There are no conflicts of interest.

Defective heat moisture exchange filter causing 'block' in anaesthesia breathing circuit.

Sir, We describe a case where a blocked heat moisture exchange (HME) filter was missed in the pre-anaesthesia machine check leading to a potentially life-threatening situation. An American Society of Anaesthesiologists physical status I, female patient was scheduled for exploratory laparotomy. Anaesthesia Machine (Datex Ohmeda S/5 Avance®) with disposable anaesthesia breathing circuit from “Airway Surgicals®,” was used for the case. Anaesthesia machine was checked as per the Association of Anaesthetists of Great Britain and Ireland (AAGBI) recommendations, and standard monitoring recommended by AAGBI was attached to the patient.[1] The patient was pre-oxygenated and administered glycopyrrolate 0.2 mg, fentanyl 100 μg and propofol 120 mg intravenously. Once the patient stopped breathing, mask ventilation was attempted which was unsuccessful even after insertion of an oral airway. The immediate concern was that this was an unanticipated difficult airway. As the patient was apnoeic and adequately relaxed under the effect of propofol, the airway was quickly secured by endotracheal intubation. The airway resistance remained high after intubation and auscultation revealed a silent chest. Considering bronchospasm as a likely cause, intravenous hydrocortisone and vecuronium were administered and the depth of anaesthesia was increased with sevoflurane. There was no change in the resistance to ventilation, but the capnography showed a trace of low amplitude. As the reservoir bag felt different, some malfunction of the anaesthesia equipment was suspected. A non-rebreathing (AMBU) bag was connected with the filter and catheter mount in the circuit, but the air entry did not improve. The catheter mount and filter were removed immediately, and the AMBU bag was directly connected to the tube and the lungs could be ventilated easily. Air entry was bilaterally equal. ETCO2 trace was normal and airway pressure was also reduced. Auscultation of the chest showed clear breath sounds. It was evident that the problem was due to blocked filter which was immediately replaced. The surgery was completed and the patient made an uneventful recovery from anaesthesia. The oxygen saturation did not drop below 96% at any point during the episode. Possibly, there was some air entry in the lungs through the blocked filter, and the actions described above were carried out swiftly with the help of other anaesthetists who were in the theatre complex. On subsequent investigation, it was discovered that the two bag test was completed without connecting the HME filter and catheter mount.[2] Probably, the obstruction in the breathing system would have been picked up, had the circuit been completely assembled while checking. Obstructions in the anaesthesia breathing circuits have been reported due to various foreign bodies.[3] We concluded that the HME filter had a manufacturing defect on the basis of elimination. The filter was dismantled and assessed. It consisted of two discs, one of green foam and another thin white papery disc. On using individual components of the filter, it was evident that the green foam of the filter was blocked. On pressing the oxygen flush, the blast could not be felt at the tube connector end. As there was no possible technique to confirm the structural defect in the foam, one possibility that can be considered is compression of the disc in the filter making them impermeable. This report adequately delineates the importance of anticipating problems and finding prompt solutions by stepwise exclusion of apparatus failure. Anticipating trouble, innovating and learning from the experience of others are inherent in the anaesthesia community. An important learning point from this case is, in the event of ‘Tight Bag’ during anaesthesia, the anaesthesia circuit should be immediately replaced by the AMBU bag at the end of the endotracheal tube.[4] This will ensure that the patient is safely oxygenated while the equipment issues are resolved. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.

病理解剖で明らかとなった肝内胆管癌からの腫瘍塞栓性肺微小血管障害の1例(Pulmonary tumor thrombotic microangiopathy caused by intrahepatic cholangiocarcinoma)

腫瘍塞栓性肺微小血管障害（pulmonary tumor thrombotic microangiopathy: PTTM）は，肺動脈腫瘍塞栓の特殊な型として報告された新しい疾患概念である。前医にて慢性閉塞性肺疾患に対するリハビリ目的で入院中の71歳男性が，突然の低酸素血症を伴うショックを呈し当院へ救急搬送となった。造影CT検査により肺塞栓症は否定されたが，来院6時間後，急速な酸素化障害から心停止に至りECMO（extracorporeal membranous oxygenation）を導入した。著明な肺高血圧状態にあることが判明したが，治療抵抗性であり入院8日目にECMO離脱困難のまま死亡となった。その後の病理組織診断にて肝内胆管癌由来のPTTMであることが判明した。PTTMは肺動脈内皮の増生を伴う腫瘍塞栓が特徴的な病態で，本症例のように急性増悪する肺高血圧症を認めた際に鑑別を要する病態と考えられる。 Pulmonary tumor thrombotic microangiopathy (PTTM) is a new disease concept that has been reported as a specific type of pulmonary tumor embolism. A 71–year–old man who was undergoing rehabilitation for chronic obstructive pulmonary disease in a different hospital was transported to our hospital due to sudden shock with hypoxia. Initial CT examination was negative for acute pulmonary embolism. Six hours after admission, he went into cardiac arrest following rapid progression of impaired oxygenation, and percutaneous cardiopulmonary support was introduced. Remarkable pulmonary hypertension was identified that was intractable to treatment, and it eventually led to his death 8 days after admission. Subsequent pathological diagnosis revealed the presence of PTTM derived from intrahepatic cholangiocarcinoma. PTTM is characterized by tumor emboli accompanied by endothelial proliferation in the pulmonary vasculature. It should be considered as one differential diagnosis when a patient presents with acute progressive pulmonary hypertension as in this case. 救急領域において，肺高血圧を伴う急性呼吸不全の原因検索は，治療方針の決定のために重要となる。本症例は急速進行性かつ治療抵抗性の肺高血圧を呈し原因不明のまま死に至り，その後の病理組織診断により腫瘍塞栓性肺微小血管障害（pulmonary tumor thrombotic microangiopathy: PTTM）を基盤とする病態であったことが明らかになった1例である。 71歳の男性である。60歳までの40年間の喫煙歴（20本/日）があり，高血圧で内服加療中であった。当院への入院1か月ほど前より労作時呼吸困難が出現したために前医を受診し，慢性閉塞性肺疾患（chronic obstructive pulmonary disease: COPD）と診断され入院となった。入院時の心エコー検査では，異常所見は認められなかった。入院18日目，仰臥位から側臥位への体位変換後に突然の呼吸苦とSpO2の低下を認め，ショック状態となった。血液ガス検査では，pH 7.2，PaO2 71mmHg，PaCO2 21.5mmHg，BE –15mmol/L（O2 8L/minリザーバーマスク投与下）と代謝性アシドーシスを伴う低酸素血症を認めた。輸液負荷と非侵襲的陽圧換気の導入によりショックは一時的に解除された。翌日に精査・集中治療目的に当院へ緊急搬送となった。 当院入院時の身体所見は，血圧115/69mmHg，心拍数115bpmで整，呼吸数26/分，SpO2 96%，腋窩体温37.2°C，意識清明で問診聴取は可能であった。聴診上ラ音は聴取せず，右季肋部に圧痛を認めたが反跳痛や筋性防御は認められなかった。動脈血液ガス分析上では，著しい酸素化の障害と極端な過換気を呈していた（Table 1）。血液検査では，白血球増多を伴わないCRPの軽度上昇と貧血，血小板減少を認めた。間接型優位の高ビリルビン血症が存在し，著明なトランスアミナーゼ，LDHの上昇を伴っていた。ヘモグロビン尿を認め，血清総ハプトグロビン値は測定閾値以下であった。D–ダイマーは増加していた（Table 1）。来院時の胸部X線は気腫性変化を認めるのみであった。胸部CT検査所見は前医と著変なく気管支壁の軽度肥厚と両側肺野の気腫性変化を伴っていたが，主幹肺動脈内に血栓は同定されなかった（Fig. 1a）。腹部CT検査では，肝臓に数mm径の多発性結節影，壁肥厚を伴う胆嚢腫大と周囲の限局性腹水，傍大動脈リンパ節腫脹を認めた（Fig. 1b）。心電図上は異常所見を認めなかった。 (O2 10L/min) (mask with reservoir bag) Findings of CT scan on admission. a: Contrast–enhanced CT imaging of the chest. Filling defect suggesting pulmonary thrombosis/embolism could not be detected. b: Contrast–enhanced CT imaging of the abdomen. The CT showed thickening of the gallbladder wall with surrounding fluid (circle), paraaortic lymphadenopathy (arrow), and multiple low density nodules in the liver (square). c: Ultrasonic cardiography after the resuscitation from cardiac arrest. It revealed that the right ventricle dilated obviously in association with collapse of the left ventricle. RV and LV indicate right ventricle and left ventricle, respectively. 以上より，入院当初は画像所見より急性胆嚢炎からの敗血症性ショックを考慮し，抗菌剤投与とハプトグロビン投与を行い，人工呼吸器管理を視野に入れながら精査・加療方針を立てることになった。その途上，入院約4時間後に突然不穏状態となり，モニター上SpO2の低下が急速に進行し始めた後に血圧が急激に低下し心停止となった。初期波形は心静止であり，速やかに心肺蘇生を開始したが循環虚脱が持続したためECMO（extra–corporeal membranous oxygenation）を導入し，心停止から23分後に心拍再開を得た。 心拍再開直後，再度速やかに造影CT検査を行ったが，主幹肺動脈に塞栓像は認められなかった。心エコー検査では，前医で認めていなかった左室の虚脱を伴う著明な右室の拡張像が認められ（Fig. 1c），高度な肺高血圧症を基礎病態として低酸素血症が急速に進行したために心停止に至ったものと考えられた。しかし，なぜ肺高血圧症が急速に出現したのか，その時点では原因を指摘することができなかった。Swan–Ganzカテーテルを挿入にて高度な肺高血圧状態にあることが確認され，一酸化窒素吸入やミルリノン静注療法を順次開始した（Fig. 2）。第3病日には，胸骨圧迫が原因と考えられる心嚢液貯留を認めたため，心嚢開窓術を施行した。いずれの治療効果も乏しく，平均肺動脈圧 60mmHg前後，中心静脈圧 46mmHg，CI 1.0 L/min/m2とさらに肺高血圧症の進行を認めた。ECMO下にても循環動態維持困難となり，第7病日に死亡確認となった。家族に承諾の上，病理解剖を施行した。 Clinical course after admission. Polygonal lines: systoric and diastolic arterial blood pressure, Crosses: mean pulmonary arterial pressure, Closed circles: cardiac index, NO: nitrogen monoxide, CPA: cardiopulmonary arrest, iv: intravenous injection, V–A ECMO: venous–arterial extracorporeal membrane oxygenation 病理所見上，両肺ともに出血性肺梗塞を認め，肺動脈に関しては毛細血管から径200μm前後の細動脈まで様々な径の血管内に，肺静脈については径1,000μm前後の細静脈内にまで腫瘍塞栓を多発性に認めた（Fig. 3a）。同時に，再疎通を伴う器質化フィブリン血栓を認め（Fig. 3a），血管壁は内膜の線維性肥厚を伴い（Fig. 3b），肺腫瘍塞栓性肺微小血管障害（PTTM）と診断した。肝臓のマクロ所見では，区域を越えて白色調の結節が散在していた。HE染色にて，壊死を伴い腺腔形成の乏しい異型上皮が小胞巣を形成し増生する像が主体で，一部腺腔形成を示す領域が認められた。異型上皮は非腫瘍肝索との連続性を認め，腫瘍胞巣辺縁では置換性発育を示し，腫瘍胞巣内部では既存門脈域構造が保持されていた。腫瘍細胞はCK（cytokeratin）7陽性，CK20陰性，EMA（epithelial membrane antigen）陽性，HSA（hepatocyte specific antigen）陰性であり，HE染色による形態学的特徴と合わせて，肝内胆管癌であることが判明した。大動脈周囲，肝門部，肺門部・縦隔，鎖骨窩の頸部リンパ節には細胆管癌の転移が認められ，さらには占拠された転移腫瘍細胞による骨髄抑制所見を得た。胆嚢には組織学的に明らかな炎症所見は指摘し得なかった。以上より，病理診断によって本病態は肝内胆管癌を基礎に持つPTTMであることが明らかになった。 Pathological findings of the lung and the liver. a, b: Hematoxylin and Eosin staining (a) revealed tumor emboli (black arrow) and thrombus formation (white arrow) followed by recanalization (black arrowhead) in the vessel. In addition, intimal thickening (white arrowheads) was observed by Elastica van Gieson staining (b). c: The images of immunohistochemistry to detect the expression of growth factors related to pathogenesis of PTTM. The embolized tumor cells inside the lung vessel expressed PDGF, Osteopontin, FGF–2, and VEGF, respectively (Magnification×200). 壁肥厚を伴う胆嚢腫大は右心系容量負荷に続発するうっ血によるもの，さらに頻回の輸血を要した貧血と血小板減少は骨髄転移による骨髄抑制が関与していたものであることが判明した。 その後，腫瘍から分泌され血管内膜の線維性肥厚を促進する可能性があるいくつかの因子に関して，病理組織標本を用いて免疫組織化学的に解析したところ，肺病変部の腫瘍細胞においてplatelet–derived growth factor（PDGF），osteopontin（OPN），fibroblast growth factor–2（FGF–2），vascular endothelial growth factor（VEGF）の発現を認めた（Fig. 3c）。一方，保存検体における各因子の血中濃度は正常範囲内であった。 本症例は，急速進行性かつ治療抵抗性の肺高血圧症にて死亡に至り，病理解剖でPTTMとの確定診断に至った一症例である。1987年，Goldhaberらは病理組織学的に筋性動脈以上の径をもつ肺動脈に腫瘍塞栓が存在するものを肺動脈腫瘍塞栓症と定義した 1。これに対し1990年，Herbayらは肺動脈腫瘍塞栓症の特殊型として，pulmonary tumor thrombotic microangiopathyを報告した。血管病変の首座が肺小動脈及び細動脈にあり，血管病変の首座が肺小動脈および細動脈にあるものを新たな疾患概念として確立し，pulmonary tumor thrombotic microangiopathy（PTTM）と呼称した 2。血管内腫瘍塞栓に加えて内膜の線維性肥厚および血栓の器質化と再疎通を伴っていることが特徴的である。本症例においても血管径約200μm以下の細動脈を中心に，これらの組織所見が確認できたことよりPTTMとの診断に至った。 PTTMにおける肺血管内腔狭窄の病因として，腫瘍細胞から分泌されるVEGF 3，FGF，OPN 3，PDGF 4などの成長因子群により内膜の線維細胞増生が誘導される機序が推定されている 5。我々の免疫組織学的な検索においても，肺血管内の腫瘍細胞に同因子群の発現が確認された。これらの成長因子群は血中での上昇が認められず，肺血管内で局所的に作用してPTTMを誘導している可能性が示唆された。 臨床的には呼吸困難，咳嗽，全身倦怠感等を主訴とする予後不良な病態である。山口らは，無症候のうちに微小な肺動脈の腫瘍塞栓を繰り返すことで血管内膜の肥厚や線維化を来し，ある閾値を超えてから肺高血圧症の症状が出現すると示唆している 6。我々が調べた限りでは，本邦におけるPTTMの症例報告は医学中央雑誌で27編30症例存在する。このうち，死亡経過が明記された24例の入院後生存期間は14.9日であった。24例中16例が7日以内に死亡しており，PTTMは入院管理が必要となる病態から死亡に至るまでは急速に病勢が進行していくものと考えられる。本症例では，前医入院1か月ほど前から労作時呼吸困難感が出現しているため，その時期にはPTTMの病態は形成され始めており，低酸素血症が先行する突然の循環虚脱は，既存の肺血管内腔狭窄を基盤にしてびまん性に腫瘍塞栓や血管攣縮が急激に生じて誘導されたものではないかと推測している。 本症例では前医入院中に突然のショックを伴う呼吸不全を呈したことで，まずは急性肺動脈塞栓症を疑ったが造影CT検査により否定された。心エコー検査上では，著明な右心負荷を伴う左心圧排像を示し，左心系への血液流入が抑制されることによるcardiac index（CI）の低下を来していたが，明らかな肺高血圧症を引き起こす左心疾患は指摘できなかった。軽度COPDと診断されていたが，肺炎などCOPDを増悪因子も存在せず，病態が急速進行性であるため慢性呼吸器疾患の進行による肺高血圧症も否定された。一方で本症例では，著明な溶血所見を伴っていたことが特徴的であった。肺高血圧所見を検査上得るまでは，敗血症に伴う一連の全身症状と考えて治療の初期対応を行ったが，結果的には各種培養と病理所見からは本病態における感染症の関与は指摘できなかった。また，自己免疫機序により肺高血圧症，溶血性貧血等の全身症状が急速に出現した可能性も考えられたが，前医までは基盤となる自己免疫疾患を示唆する所見や自己免疫を賦活化させる感染，薬剤投与等のエピソードが無く，実際に特異的な組織学的炎症所見も得られなかった。結果的に，溶血性要因はPTTMを基礎とした肺血管内狭窄による機械的な赤血球破壊によるものと明らかになった。我々が検索した国内外のPTTM症例報告でビリルビン値が記載されている14文献のうち，間接型ビリルビンの上昇を認めた症例は4件あるが，それらが溶血性要因によるものであるかどうかは不明であり，病期の進んだPTTMにおいて赤血球破壊が誘導される現象が特徴的な臨床診断としての指標になり得るのかどうかは今後の検討が必要である。 Herbayらは，300例の固形癌患者の剖検所見において21例（7%）でPTTMが存在していたと報告 2している。PTTMの原発腫瘍としては半数以上が胃癌で，肺癌がそれに続いている 2。我々が医学中央雑誌およびPubMedの国内外の症例報告を検索した限りでは，本症例が初めての肝内胆管癌を起因とするPTTMの報告となる。PTTMを引き起こしやすい癌の細胞特性に何らかの共通性がないかを検索することは，PTTMを制御する薬剤の開発を目指す上でも重要と考えられる。残念ながら，現在PTTMに対する根治的治療法は存在しない。一度進行した肺高血圧の症状を呈すると，本症例のように治療抵抗性に一気に病勢が進行し得る疾患である。末期的なPTTMと診断されれば，その予後を考慮した集中治療方針が決定されることもあるであろう。救急・集中治療において，原因不明の肺高血圧症を認知したら，積極的に胆癌の可能性を疑いPTTMの鑑別を行う必要がある。 急速進行性の肺高血圧症にて死亡に至り，肝内胆管癌由来のPTTMとの病理組織診断を得た1例を経験した。 本論文における利益相反はない。

Hyperbaric therapy and diving medicine - diving medicine - present state and prospects

The diving accident (decompression incident, DCI) occurs in the decompression phase of dives. The DCI can either be caused by an arterial gas embolism (AGE) subsequent to a pulmonary barotrauma or by the formation of inert gas bubbles subsequent to a reduction of ambient pressure during the ascent from depth. In contrast to the traditional assumption that decompression incidents only occur if decompression rules are neglected, recent data indicate that a vast amount of diving accidents occur even though divers adhered to the rules. Hence, there is a large inter- and intraindividual variability in the predisposition for diving accidents. Within the past few years, the molecular understanding of the pathophysiology of diving accidents has improved considerably. It is now well accepted that pro-inflammatory and pro-coagulatory mechanisms play a central role. Moreover, microparticles are increasingly discussed in the pathogenesis of diving accidents. These new molecular findings have not yet resulted in new therapeutic approaches. However, new approaches of preconditioning before the dive have been developed which are intended to reduce the risk of diving accidents. The symptoms of a diving accident show a large variability and range. They reach from pruritus over tension in the female breast, marbled skin and pain in the joints to severe neurological disability like paraplegia or hemiplegia. Furthermore, pulmonary symptoms can be a result of a pulmonary gas embolism and/or a tension pneumothorax. Extreme cases can also manifest as generalized, difficult-to-treat seizures, loss of consciousness or even death. The evidence-based therapy of diving accidents consists of an immediate application of 100% inspiratory O2. This can be performed via a demand valve, face mask with reservoir bag or ventilation bag connected to a reservoir bag. Fluid substitution is performed by i. v. infusion of 500-1000ml/h of cristalloids. If consciousness is not impaired, the diver is positioned in a supine position, in case of impaired or absent consciousness in a lateral recovery position. Especially in severe cases of DCI a fast transfer to a qualified hyperbaric center and the earliest possible hyperbaric O2-therapy is essential.

In vitro study of Magnetic Resonance Imaging artifacts of anesthetic devices

Background: Deep sedation or general anesthesia is usually required for Magnetic Resonance Imaging when patients cannot remain motionless in the suite. Various anesthetic devices have been used to maintain the airway and ventilate the lungs during this period. Some of them produce artifacts that pose difficulties in the interpretation of images. The aim of this study was to identify the devices that produced artifacts during Magnetic Resonance Imaging.Methods: Twelve anesthetic devices were considered: oro-pharyngeal airway, nasopharygeal airway, face mask with reservoir bag, nasal cannula, endotracheal tube, disposable Ambu Laryngeal Mask Airway, Laryngeal Mask Airway Unique, Disposable Laryngeal Tube Sonda, i-gel, Ambu bag, Bain Circuit, Jackson Rees Circuit. Magnetic Resonance Imaging was performed with each device placed on the top of a phantom simulator respectively to resemble the position in vivo.Results: The artifacts with Disposable Laryngeal Tube Sonda, Laryngeal Mask Airway Unique and endotracheal tube were related to ferromagnetic material in the pilot valve and were similar. No artifacts were found with oro-pharyngeal airway, nasopharygeal airway, nasal cannula, endo-tracheal tube with pilot valve detached, face masks with reservoir bag (metal removed), Ambu bag (without Adjustable Pressure Limiting valve), i-gel , disposable Ambu Laryngeal Mask Airway, Bain Circuit and Jackson Rees Circuit.Conclusion: Anesthetic devices that produce Magnetic Resonance Imaging artifacts are disposable Laryngeal Tube Sonda, Laryngeal Mask Airway Unique and Endotracheal Tube.Journal of Society of Anesthesiologists of Nepal 2015; 2(1): 13-16

High flow nasal cannula oxygen (hfnc) versus non-invasive positive pressure ventilation (nippv) in acute hypoxemic respiratory failure. a pilot randomized controlled trial

Oxygen therapy is generally provided via nasal cannula, non-rebreathing masks and masks with reservoir bags. These devices have various limitations. Despite showing clear benefits in certain conditions, non-invasive positive pressure ventilation (NIPPV) limits mobilization, restricts communication and oral nutrition and is poorly tolerated by some patients due to discomfort. High-flow nasal cannula oxygen (HFNC) delivers a high flow of heated and humidified oxygen through nasal prongs. It generate positive airway pressure, reduces respiratory dead space, airway resistance, and less frequent interruption of therapy.

Evolution of apnoea test in brain death diagnostics.

The concept of brain death (BD) was initially described in 1959 and subsequently became widely accepted in the majority of countries. Nevertheless, the diagnostic guidelines for BD markedly differ, especially regarding the apnoea test (AT), a crucial element of clinical BD confirmation. The current basic guidelines recommend preoxygenation rather than disconnection from the ventilator and insertion of an oxygen insufflation catheter into the endotracheal tube. Although a properly prepared and conducted AT is relatively safe, it has to be aborted in cases of serious disturbances, such as severe cardiac arrhythmia, cardiac arrest, hypotension, hypercarbia, desaturation and tension pneumothorax. These complications may be more frequent in patients with previously existing risk factors, such as poor oxygenation, severe acidosis, hypotension and cardiac rhythm disturbances. Airway injuries can occur if the insufflation catheter is placed too deep or catheter-related obstruction of the intubation tube occurs. It is widely accepted that AT should be performed as the very last BD diagnostic procedure due to its possible lethal consequences. Reports concerning the possible pitfalls of AT and confounding situations have inspired attempts to determine the most effective and safe method of AT. The use of CPAP with oxygen supplementation is becoming highly popular. CPAP can be generated in three manners: directly by the ventilator; through the use of a CPAP valve with a reservoir; and through the use of a highly traditional T-piece system with a reservoir bag connected to distal tubing immersed in water.

Use of high-flow nasal cannula oxygen therapy to prevent desaturation during tracheal intubation of intensive care patients with mild-to-moderate hypoxemia.

Tracheal intubation of ICU patients is frequently associated with severe hypoxemia. Although noninvasive ventilation reduces desaturation during intubation of severely hypoxemic patients, it does not allow for per-procedure oxygenation and has not been evaluated in mild-to-moderate hypoxemic patients for whom high-flow nasal cannula oxygen may be an alternative. We sought to compare pre- and per-procedure oxygenation with either a nonrebreathing bag reservoir facemask or a high-flow nasal cannula oxygen during tracheal intubation of ICU patients. Prospective quasi-experimental before-after study (ClinicalTrials.gov: NCT01699880). University hospital medico-surgical ICU. All adult patients requiring tracheal intubation in the ICU were eligible. In the control (before) period, preoxygenation was performed with a nonrebreathing bag reservoir facemask and in the change of practice (after) period, with high-flow nasal cannula oxygen. Primary outcome was median lowest SpO2 during intubation, and secondary outcomes were SpO2 after preoxygenation and number of patients with saturation less than 80%. One hundred one patients were included. Median lowest SpO2 during intubation were 94% (83-98.5) with the nonrebreathing bag reservoir facemask versus 100% (95-100) with high-flow nasal cannula oxygen (p < 0.0001). SpO2 values at the end of preoxygenation were higher with high-flow nasal cannula oxygen than with nonrebreathing bag reservoir facemask and were correlated with the lowest SpO2 reached during the intubation procedure (r = 0.38, p < 0.0001). Patients in the nonrebreathing bag reservoir facemask group experienced more episodes of severe hypoxemia (2% vs 14%, p = 0.03). In the multivariate analysis, preoxygenation with high-flow nasal cannula oxygen was an independent protective factor of the occurrence of severe hypoxemia (odds ratio, 0.146; 95% CI, 0.01-0.90; p = 0.037). High-flow nasal cannula oxygen significantly improved preoxygenation and reduced prevalence of severe hypoxemia compared with nonrebreathing bag reservoir facemask. Its use could improve patient safety during intubation.

Comparison between transthoracic lung ultrasound and a clinical method in confirming the position of double-lumen tube in thoracic anesthesia. A pilot study

ObjectiveTo compare the ability of lung ultrasound and a clinical method in the confirmation of a selective bronchial intubation by left double-lumen tube in elective thoracic surgery. Material and methodsA prospective and blind, observational study was conducted in the setting of a university hospital operating room assigned for thoracic surgery. A single group of 105 consecutive patients from a total of 130 were included. After blind intubation, the position of the tube was confirmed by clinical and ultrasound assessment. Finally, the fiberoptic bronchoscopy confirmation as a reference standard was used to confirm the position of the tube. Under manual ventilation, by sequentially clamping the tracheal and bronchial limbs of the tube, clinical confirmation was made by auscultation, capnography, visualizing the chest wall expansion, and perceiving the lung compliance in the reservoir bag. Ultrasound confirmation was obtained by visualizing lung sliding, diaphragmatic movements, and the appearance of lung pulse sign. ResultsThe sensitivity of the clinical method was 84.5%, with a specificity of 41.1%. The positive and negative likelihood ratio was 1.44 and 0.38, respectively. The sensitivity of the ultrasound method was 98.6%, specificity was 52.9%, with a positive likelihood ratio of 2.10 and a negative likelihood ratio of 0.03. Comparisons between the diagnostic performance of the 2 methods were calculated with McNemar's test. There was a significant difference in sensitivity between the ultrasound method and the clinical method (P=.002). Nevertheless, there was no statistically significant difference in specificity between both methods (P=.34). A P value<.01 was considered statistically significant. ConclusionLung ultrasound was superior to the clinical method in confirming the adequate position of the left double-lumen tube. On the other hand, in confirming the misplacement of the tube, differences between both methods could not be ensured.

Light protection of chemotherapy drugs for infusion

Specific chemotherapy drugs which require to be delivered by continuous infusion over time can have their effectiveness impaired by exposure to optical radiation. Mechanisms and processes of drug preparation and patient administration associated with light sensitive drugs were monitored within a Chemotherapy Unit. Levels of ambient light at locations of drug preparation/administration and levels of protection afforded by optical filter elements such as infusion lines were determined using a double grating Bentham Dmc150 spectroradiometer. Models of light exposure were developed for separate components of drug preparation and infusion delivery systems where the latter included the fluid bag with protective light cover, drip chamber and giving set line. In addition, the attenuation coefficient of Dacarbazine at the concentration typically used in patient treatments was determined using specially manufactured measurement cells. The relative contributions to light absorption of the drug bag, drip chamber and patient line were identified for specific types of giving sets, spectral content/intensity of light exposure and specific drug light absorption profiles. This indicated significant differences in the level of light protection afforded by specific giving sets and either single or double layer protection of the drug bag reservoir. It is not clear, however, if these variations could lead to significant differences of levels of drug de-activation and/or creation of undesirable photo-products such as in the case of Dacarbazine. Such techniques, however, provide a means of identifying how light exposure can be maintained at levels as low as reasonably possible as a precautionary measure.

Oxygenation With a Single Portable Pulse-Dose Oxygen-Conserving Device and Combined Stationary and Portable Oxygen Delivery Devices in Subjects With COPD.

Portable oxygen devices simplify and facilitate patient therapy. This study was designed to compare S(pO2) and patient satisfaction with a portable oxygen concentrator or a combined system consisting of a fixed device with continuous-flow oxygen dispensation and a portable device with pulse dispensation for ambulation. This crossover trial assessed 25 subjects with COPD (92% men, mean age of 72.2 ± 7.4 y, mean FEV1 of 34.14 ± 12.51% of predicted) at 4 hospitals in Madrid. All subjects had previously used the combined system, consisting of a fixed oxygenation system and a portable system for ambulation, with 16 (64%) using stationary and portable concentrators and 9 (36%) using a stationary reservoir and portable liquid oxygen bag. Oxygenation settings at rest and while walking were determined at baseline. Subjects were maintained on the previous combined system for 1 week and then switched to the portable oxygen concentrator for 1 week. Mean S(pO2) over 24 h was calculated using the software in the oximeter, and compliance was monitored (Visionox). Low S(pO2) (< 90%) was significantly more frequent during use of the portable concentrator alone than with the combined system (37.1% vs 18.4%, P < .05). The portable system alone was preferred by 43% of subjects, and the combined system was preferred by 36%, whereas 21% were not sure. Subjects preferred using a single portable oxygenation system both at home and during ambulation. Portable systems alone, however, did not supply the same levels of oxygenation as the combination of fixed and portable systems. Before the widespread adoption of portable systems as a single device, additional studies are needed to determine best-practice protocols for adjustment of daytime and nighttime oxygenation settings. (ClinicalTrials.gov registration NCT02079753).

Alveolar recruitment maneuvers under general anesthesia: a systematic review of the literature.

The sigh is a normal homeostatic reflex that maintains lung compliance and decreases atelectasis. General anesthesia abolishes the sigh reflex with rapid onset of atelectasis in 100% of patients. Studies show a strong correlation between atelectasis and postoperative pulmonary complications, raising health-care costs. Alveolar recruitment maneuvers recruit collapsed alveoli, increase gas exchange, and improve arterial oxygenation. There is no consensus in the literature about the benefits of alveolar recruitment maneuvers. A systematic review is necessary to delineate their usefulness. The search strategy included utilizing PubMed, CINAHL, the Cochrane Library, the National Guideline Clearinghouse, and all subsequent research reference lists up to January 2014. Inclusion criteria involved studies that compared the use of an alveolar recruitment maneuver with a control group lacking an alveolar recruitment maneuver in adult surgical subjects not suffering from ARDS or undergoing cardiac or thoracic surgeries. Six randomized controlled trials of the 439 studies initially identified achieved a score of ≥ 3 on the Jadad scale and were included in this review. Alveolar recruitment maneuvers consisted of a stepwise increase in tidal volume to a plateau pressure of 30 cm H2O, a stepwise increase in PEEP to 20 cm H2O, or sustained manual inflations of the anesthesia reservoir bag to a peak inspiratory pressure of 40 cm H2O. Subjects in the alveolar recruitment maneuver groups experienced a higher intraoperative PaO2 with improved lung compliance. Different alveolar recruitment maneuvers were equally effective. There was a significant advantage when alveolar recruitment maneuvers were followed by PEEP application. Alveolar recruitment maneuvers followed by PEEP should be instituted after induction of general anesthesia, routinely during maintenance, and in the presence of a falling SpO2 whenever feasible. They allow the anesthesia provider to reduce the FIO2 while maintaining a higher SpO2 , limiting the masking of shunts. Utilization of alveolar recruitment maneuvers may reduce postoperative pulmonary complications and improve patient outcomes.