Ventilation In Supine Position Research Articles

Early Prone Position Ventilation in the Efficacy for Severe Hypoxemia and Neurological Complications Following Acute Type A Aortic Dissection (TAAD) Surgery

Objective To analyze the efficacy of early prone position ventilation in the treatment of severe hypoxemia after surgery for acute type A aortic dissection (TAAD). Methods The patients were divided into a control group and a treatment group. Parameters assessed included blood gas analysis indicators [arterial oxygen partial pressure (PaO2). Results: (1) Blood gas analysis: Before treatment, there was no significant difference in PaO2, SpO2, and OI levels between the two groups; after treatment, the PaO2, SpO2, and OI levels in both groups significantly increased compared to pre-treatment, with a more pronounced improvement in the treatment group than in the control group (p < 0.05). (2) Hemodynamics: Before treatment, there was no significant difference in MAP and HR levels between the two groups; after treatment, the MAP levels increased significantly in both groups compared to pre-treatment, while HR levels decreased significantly, with no significant difference between the groups. (3) Prognosis recovery: MV time, ICU stay, and total hospital stay were significantly lower in the treatment group than in the control group; the 30-day mortality rate was 14.58% in the control group and 12.50% in the treatment group, with no significant difference in 30-day mortality rate between the groups. Conclusion Early prone position ventilation has shown promising application in the treatment of severe hypoxemia after TAAD surgery. Compared to traditional supine position ventilation, the use of early prone position ventilation can further improve blood gas analysis indicators in patients, and shorten MV time, ICU stay, and total hospital stay, thereby accelerating patient recovery.

Prone position ventilation for the relief of acute respiratory distress syndrome through improved pulmonary ventilation: Efficacy and safety.

At present, there is a preliminary clinical consensus that prone position ventilation (PPV) is beneficial to the treatment of acute respiratory distress syndrome (ARDS), and further research on the details of treatment and patients' benefits will help to assess its effectiveness and safety. To evaluate the timing, efficacy, and safety of different mechanical ventilation positions (MVP) in treating ARDS. The results of clinical trials were directly or indirectly compared by network meta-analysis to compare the effects of different MVP. Two authors independently searched the papers published in PubMed, Embase, Cochrane Library, China Knowledge Infrastructure (CNKI), China Biomedical Discs (CBM), WanFang, and VIP database from January 2000 to August 2022. The outcome indicators were oxygenation index, mechanical ventilation time, ICU hospitalization time, in-hospital mortality, and incidence of adverse events. Two authors independently screened the literature, evaluated the quality of the studies, and completed the data extraction. Stata 14.0 was used to conduct a network Meta-analysis, and the intervention measures were ranked according to the surface under the cumulative ranking curve (SUCRA). Funnel plots were drawn to evaluate publication bias. According to the inclusion and exclusion criteria, 75 studies (including 6333 patient data) were finally included. According to the analysis results, PPV was the best for improving the oxygenation index. The SUCRA values of mechanical ventilation time, ICU hospitalization time, and in-hospital mortality were ranked as PPV > lateral position ventilation (LPV) > supine position ventilation (SuPV) > semireclining position ventilation (SePV). The SUCRA values in the incidence of adverse events were ranked as LPV > PPV > SuPV > SePV. All outcome measures had good consistency and low statistical heterogeneity. Funnel plot analysis shows that papers reported within three days of mechanical ventilation time, over five days of mechanical ventilation time, and in-hospital mortality were more likely to have publication bias. PPV has the best effect on improving the oxygenation index, reducing mechanical ventilation time, shortening ICU hospitalization time, and reducing in-hospital mortality. Early and long-term use of PPV to improve pulmonary ventilatory function will be the key to improving patients' survival and quality of life with ARDS. PPV significantly affects patients with ARDS, which can shorten the treatment time and reduce hospital costs. During the treatment, nursing observation should be strengthened to prevent adverse events.

腹臥位から仰臥位へ体位交換時に肺血栓塞栓症を発症した重症COVID–19肺炎の2例(Two cases of pulmonary embolism after position change from prone position during mechanical ventilation due to severe COVID–19 pneumonia)

COVID–19肺炎では腹臥位呼吸療法の有効性が注目されている。今回，腹臥位から仰臥位への体位交換時に発症した肺血栓塞栓症を2例経験したので報告する。1例目は59歳の男性，発症11日目に人工呼吸を開始し，15日目から腹臥位呼吸療法を開始した。17日目に仰臥位へ体位交換した30分後より，SpO2が94%から85%へと低下し，心拍数も90bpmから120bpmへ上昇した。D–ダイマーが9.2μg/mLから22.5μg/mLへ上昇していたため，肺血栓塞栓症を疑い，造影CTで左肺動脈血栓が判明した。2例目は46歳の男性，発症13日目で人工呼吸を開始し，同日腹臥位呼吸療法を開始した。14日目に仰臥位へ体位交換した10分後より血圧低下，12分後からSpO2が97%から84%へと低下した。D–ダイマーが5.6μg/mLから48.1μg/mLへ上昇していたことと，心臓超音波検査で右心負荷所見がみられたことから肺血栓塞栓症を疑い，造影CTで左内頸静脈血栓と右肺動脈血栓が判明した。今回の2症例は，いずれも腹臥位から仰臥位に体位交換した際に肺血栓塞栓症を発症しており，いずれも中心静脈カテーテル挿入側の内頸静脈に血栓を認めた。長時間の腹臥位から仰臥位への体位交換は，内頸静脈血栓から肺血栓塞栓症を発症させる可能性が示唆され，バイタルサインに留意して行うことが望ましい。 The prone position during mechanical ventilation has been reported to be effective in respiratory failure caused by COVID–19 pneumonia. We report two cases of pulmonary thromboembolism that may have occurred during return to the supine position. A 59–year–old man, with COVID–19 pneumonia, was put on mechanical ventilation in supine position from day 11 to day 15, and prone position from day 15 to day 17. Thirty minutes after returning to the supine position on day 17, he developed hypoxemia and tachycardia. Pulmonary thromboembolism was suspected based upon elevated D–dimer levels. Echo venogram of the right internal jugular vein showed thrombi, and contrast–enhanced computed tomography (CECT) showed thrombi in the left pulmonary artery. A 46–year–old man, with COVID–19 pneumonia, was put on mechanical ventilation in prone position from day 13 to day 14. On day 14, when he was returned to the supine position, he developed hypotension after 10 minutes, and hypoxemia after 12 minutes. CECT showed thrombi in the left internal jugular vein and right pulmonary artery. During mechanical ventilation, a change to the supine position after prolonged prone position may cause pulmonary thromboembolism from thrombi in the internal jugular vein, and should be performed with attention to vital signs. 腹臥位呼吸療法は，acute respiratory distress syndrome（ARDS）の死亡率を低下させる可能性があり 1，COVID–19肺炎にもしばしば実施される。当院でも，集中治療管理を要するCOVID–19肺炎患者に対し，16時から翌日10時の18時間を腹臥位，残りの6時間を仰臥位とする腹臥位呼吸療法を施行した。腹臥位呼吸療法での合併症として，気管チューブ閉塞，事故抜管，静脈路の事故抜去，褥瘡，視力障害，腕神経叢損傷などが報告されている 2。今回，腹臥位から仰臥位への体位交換を契機に発症した肺血栓塞栓症（pulmonary embolism: PE）を2例経験したので報告する。 なお，本症例の報告は倫理委員会の承諾は不要であり，個人情報保護法に基づいて匿名化がなされ，患者・家族の同意を得ている。 患 者：59歳の男性 既往歴：痛風，脂質異常症 現病歴：発熱・頭痛で発症し，同日SARS–CoV–2 PCR陽性と判明した。発症5日目に酸素化不良のため，当院に入院となった。11日目に呼吸状態悪化のため気管挿管し，人工呼吸管理となった。 入院後経過：気管挿管後より，深部静脈血栓症（deep vein venous thrombosis: DVT）予防を目的として，ヘパリンカルシウム5,000単位の皮下注射を1日2回開始した。発症13日目に撮像した体幹部造影CTでは，PE，DVTともに指摘されなかったが，14日目にD–ダイマーが9.8µg/mLと上昇した。超音波検査で，中心静脈カテーテル挿入側である右内頸静脈に血栓を認め（Fig. 1a），リバーロキサバン15mg内服を開始した。また，13日目に撮像したCTでは背側の無気肺が著明であり，人工呼吸器関連肺炎も併発したため，背面開放と体位ドレナージを目的とし，15日目より腹臥位呼吸療法を開始した。17日目に，腹臥位から仰臥位に体位交換した30分後より，SpO2が94%から85%へと低下し，心拍数も90bpmから120bpmへ上昇した（Fig. 2）。 Case 1: Jugular vein echo (a). major and minor axis image showing right internal jugular vein (white arrow). Chest computed tomography (b). Axial view showing left main pulmonary artery thrombus (white triangle). Case 1: Course at onset of pulmonary embolism. ベッドサイドで可能な検査や理学所見では，気胸や痰による閉塞性無気肺を認めなかった。超音波検査では右心拡大を認めなかったが，依然として右内頸静脈に血栓が存在していた。両側大腿静脈，膝窩静脈には，血栓はみられなかった。右内頸静脈血栓があること，D–ダイマーが22.5µg/mLと上昇（前日9.2µg/mL）していること，また長時間の腹臥位から体位交換をした際に起きた酸素化低下と頻脈であることから，PEを強く疑った。既にリバーロキサバン内服が行われていたが，治療量でなかったため30mgに増量し，翌日待機的に造影CTを施行した。造影CTでは，左主肺動脈に血栓塞栓症がみられた（Fig. 1b）。以上の所見より，腹臥位から仰臥位への体位交換を契機に発症したPEと診断した。 その後，COVID–19肺炎後器質化肺炎に対して，プレドニゾロン60mg/day（1mg/kg）を開始した。発症25日目に38度台の発熱があり，膿性痰が出現したため，人工呼吸器関連肺炎としてピペラシリン・タゾバクタム13.5ｇ/日を投与開始した。その後のCTで，左肺に多発空洞影を認め，肺化膿症と診断した。抗菌薬治療を60日間継続した後，発症93日目に，リハビリテーション目的に転院となった。 患 者：49歳の男性 既往歴：慢性中耳炎 現病歴：咽頭痛・発熱で発症し，翌日SARS–CoV–2 PCR陽性と判明した。呼吸困難感が出現したため，発症11日目に前医入院となった。呼吸状態悪化のため翌日当院に転院となり，13日目に気管挿管を施行し，人工呼吸管理を開始した。 入院後経過：気管挿管後より，DVT予防を目的として，ヘパリンカルシウム5,000単位の皮下注射を1日2回開始した。気管挿管後も酸素化が改善しなかったため，同日夕方より腹臥位呼吸療法を開始した。翌日，腹臥位から仰臥位に体位交換した10分後から，徐々に血圧が低下し，SpO2も低下した（Fig. 3）。 Case 2: Course at onset of pulmonary embolism. ベッドサイドで可能な検査や理学所見では，気胸や痰による閉塞性無気肺を認めなかった。超音波検査では，両側大腿静脈，膝窩静脈には血栓を認めなかったが，左内頸静脈の中心静脈カテーテル周囲に血栓を認め，右心拡大も認めた。左内頸静脈血栓があること，D–ダイマーが48.1µg/mLと上昇（前日5.6µg/mL）していること，右心負荷所見があり，長時間の腹臥位から体位交換をした際に起きた血圧低下，酸素化低下であることから，PEを強く疑った。APTTの目標を50secとしてヘパリンナトリウム14,000U/dayの持続静脈注射を開始し，同日に造影CTを施行した。造影CTでは左内頸静脈（下顎角から胸鎖関節付近の鎖骨下静脈合流部），および右肺動脈に血栓を認めた（Fig. 4a, b）。 Case 2: Chest computed tomography. Axial view showing right pulmonary artery thrombus in the middle lobe (a. white triangle). Axial view showing left internal jugular vein thrombus (b. white arrow). 以上の所見より，腹臥位から仰臥位へ体位交換した際に発症したPEと診断した。発症第15日目に人工呼吸器関連肺炎を発症したため，セフェピム3g/日を投与開始した。16日目に，P/F ratioが191から289へ改善し，18日目に気管チューブを抜去した。また，19日目にヘパリンからリバーロキサバン30mg/dayへ変更し，22日目に前医に再転院となった。 PEの塞栓源は，約90%が下肢あるいは骨盤内の静脈とされている。しかし，2例とも内頸静脈に血栓があり，超音波検査と造影CTで，両下肢静脈内に明らかな血栓はみられなかった。このことから，内頸静脈血栓からの塞栓子が原因で，PEを発症したと考えられる。集中治療を行う場合，内頸静脈への中心静脈カテーテル留置を行う機会が多いが，中心静脈カテーテルの挿入は内頸静脈血栓形成のリスクとして知られている 3。また，2例ともヘパリンの予防投与を行っていたが，中心静脈カテーテル挿入側の内頸静脈に血栓を認めた。COVID–19では，血管内皮細胞にもSARS–CoV–2感染が成立する。ウイルス感染により障害された血管内皮細胞からの凝固第VIII因子とvon Willebrand factorの放出や，サイトカインストームが血栓傾向の誘引となり，深部静脈血栓症の発症率が上昇するとされている 4。 なお，今回の2症例目では，中心静脈カテーテルを挿入した同日16時ごろから翌日10時ごろまで腹臥位呼吸療法を行い，仰臥位に体位交換をした際にPEを生じている。中心静脈カテーテル挿入時の超音波検査では血栓を認めておらず，腹臥位呼吸療法を行っている18時間の間に，血栓が形成された可能性が高い。鎖骨による鎖骨下静脈合流部への圧迫で内頸静脈の血流うっ滞が生じ，内頸静脈血栓の形成に腹臥位が寄与していた可能性が考えられる。1例目においても，長時間の腹臥位が，既存の内頸静脈血栓の伸展を助長した可能性がある。このような血栓形成のリスクが重なり，ヘパリン予防投与を行っていたにもかかわらず血栓が形成されたと考えられる。 DVTは，通常発生部位から中枢へ成長する過程で，血栓中枢端や伸展血栓が遊離，もしくは血栓の静脈壁接着面が剥離して塞栓子となる。関節周囲や下腿筋ポンプ内のような特殊な状況では，起立，歩行などの際に下肢の筋肉が収縮し，伸展血栓が容易に塞栓化しやすいとされている 5。腹臥位呼吸療法において，腹臥位から仰臥位へ体位交換したことを契機としてPEを発症したという報告は，我々の渉猟する限りみられなかったが，脊椎手術では数例報告されている 6, 7。腹臥位中は，鎖骨による圧迫や胸腔内圧上昇に伴い，内頸静脈や下大静脈のうっ滞が起こることが示唆されている。腹臥位から仰臥位への体位交換で，これらが解除されることにより，血行動態が一時的に変化しうる。それにより，体位交換という受動的な運動であっても，長時間の腹臥位の間に伸展，形成された内頸静脈血栓が遊離した可能性が考えられる。 腹臥位から仰臥位に体位交換した際の酸素化低下はしばしば経験され，原病が重篤，あるいは背側無気肺が著明である場合は，対症療法を行うのみで見過ごされてしまう可能性もある。しかし，今回1例目は頻脈，2例目では血圧低下と，SpO2の低下以外にもバイタルサインの変化を認めていた。COVID–19の血栓症発症リスクが高いことも踏まえ 8, 9，PEを鑑別にあげて対応し，治療介入することができた。さらに2例目は，1例目の経験から，仰臥位への体位交換が内頸静脈血栓を塞栓子としたPE発症の契機となる可能性があることを認識していた。そのため，ベッドサイドでの超音波検査で，両側大腿静脈に加え内頸静脈も観察を行い，内頸静脈血栓を認知することができ，PEを鑑別疾患の上位に挙げることができた。なお，両症例ともPE発症日の採血でD–ダイマーの上昇がみられていた。腹臥位呼吸療法施行中のD–ダイマー上昇は，血栓形成もしくは伸展を示唆している可能性があり，仰臥位に復帰した際にバイタルサイン変動がみられた場合には，PEの発症を疑う必要があると考える。なお，ARDS患者の腹臥位では健常人と異なり，換気血流比不均等の改善による右心負荷の軽減や，左心前負荷増大により，心拍出量が増加する 10。仰臥位への体位交換時には，これらの血行動態の変化は速やかに元に戻り，心拍出量は低下する。これは，PEを発症した際の重症度を高める可能性がある。 当院では，腹臥位からの体位交換時はSpO2，心電図，end–tidal CO2などの観血的動脈圧以外の一部モニターを外していた。同様にモニターを外しており初期症状であるバイタルサインの変化を察知できずに 11，心停止まで至った脊椎手術症例の報告もある 6。今回2例とも，モニターは仰臥位復帰後早急に再装着され，バイタルサインの変化に早期に気づくことができた。モニター未装着となる時間を短縮することが，早期にPEの兆候を察知するために重要である。なお，PE発症時にSpO2低下はよくみられるが，より劇的な症例では急激にend–tidal CO2が低下することが知られており，脊椎手術中end–tidal CO2低下がPE発症覚知の一助となった報告もある 12。当院では腹臥位から仰臥位への体位交換時，end–tidal CO2モニターを外していることがほとんどであった。end–tidal CO2モニターは，頭側で回路混線せずに装着したまま安全に体位交換できるため，今後の腹臥位療法では，装着を継続して体位交換することも，検討の余地がある。 腹臥位呼吸療法時は，内頸静脈還流のうっ滞などにより形成・伸展した内頸静脈血栓が，仰臥位への体位交換で遊離しPEを発症する恐れがあるため，注意して体位交換を行う必要がある。また，腹臥位からの体位復帰時に生じる循環虚脱や肺酸素化能の低下にはPEが関与している可能性があり，これらのバイタルサインの変化を早期に察知するために，装着可能なモニターはできる限り装着を継続し，困難な場合にもモニター未装着時間を可能な限り短縮して迅速な体位交換を行うことが望ましい。 著者全員に本論文に関する利益相反はない。

Exogenous surfactant reduces inflammation and redox imbalance in rats under prone or supine mechanical ventilation.

Mechanical ventilation (MV) is a lifesaving therapy for patients with acute or chronic respiratory failure. Despite, it can also cause lung injury by inducing or worsening inflammatory responses and oxidative stress. Several clinical approaches have protective effects on the lungs, including the prone position and exogenous surfactant; however, few studies have evaluated the association between the two strategies, especially in individuals without previous lung injury. We tested the hypothesis that the effects of the homogenization in lung aeration caused by the prone position in association with the anti-inflammatory properties of exogenous surfactant pre-treatment could have a cumulative protective effect against ventilator-induced lung injury. Therefore, Wistar rats were divided into four experimental groups: Mechanical Ventilation in Supine Position (MVSP), Mechanical Ventilation in Prone position (MVPP), Mechanical Ventilation in Supine Position + surfactant (MVSPS), and Mechanical Ventilation in Prone Position + Surfactant (MVPPS). The intranasal instillation of a porcine surfactant (Curosurf®) was performed in the animals of MVSPS and MVPPS 1 h before the MV, all the rats were subjected to MV for 1 h. The prone position in association with surfactant decreased mRNA expression levels of pro-inflammatory cytokines in ventilated animals compared to the supine position; in addition, the NfκB was lower in MVPP, MVSPS and MVPPS when compared to MVSP. However, it had no effects on oxidative stress caused by MV. Pre-treatment with exogenous surfactant was more efficient in promoting lung protection than the prone position, as it also reduced oxidative damage in the lung parenchyma. Nevertheless, the surfactant did not cause additional improvements in most parameters that were also improved by the prone position. Our results indicate that the pre-treatment with exogenous surfactant, regardless of the position adopted in mechanical ventilation, preserves the original lung histoarchitecture, reduces redox imbalance, and reduces acute inflammatory responses caused by mechanical ventilation in healthy adult Wistar rats.

Changes of blood gas analysis in moderate-to-severe acute respiratory distress syndrome patients during long-term prone position ventilation: a retrospective cohort study.

Prone position ventilation (PPV) has been recommended for patients with acute respiratory distress syndrome (ARDS) to improve oxygenation. However, whether prolonged prone ventilation will aggravate hyperoxia and whether abdominal compression will aggravate permissive hypercapnia acidosis are topics of concern. We carried out a retrospective analysis to investigate the issues above. Clinical data were collected from 97 moderate-to-severe ARDS patients who received PPV as part of their treatment in the intensive care unit (ICU) of the First Affiliated Hospital of Guangzhou Medical University from November 2015 to May 2021. We collected arterial blood gas of patients according to the 3 periods: supine position ventilation (SPV), PPV early stage (within 4 hours), and PPV middle and late stage (6 hours or later). We established a linear mixed-effects models with "body position changes, times of PPV, gender, age, baseline SOFA, and baseline APACHE II" as fixed effects, and individual and the number of prone positions as random intercept and random slope to investigate the effect of body position changes on blood gas analysis. Among the 97 patients received PPV included, 51 were ICU survivors. Arterial partial pressure of oxygen (PaO2) and PaO2/fraction of inspired oxygen (FiO2) ratio were significantly higher at the early, middle and late stages of PPV than those in SPV [PFR (mmHg): 158 (118.00, 203.00) vs. 161 (129.00, 202.75) vs. 123 (91.75, 163.00), P<0.05]. Despite the synchronized reduction of FiO2, the incidence of hyperoxia in the prone position was still significantly higher than that in the supine position [hyperoxia (%):33.33 vs. 33.56 vs. 12.42, P<0.05]; there was no significant change in arterial carbon dioxide partial pressure (PaCO2) at each stage of PPV, but there was a significant increase in PH at PPV middle and late stages than those at early stage [PH: 7.39 (7.34, 7.42) vs. 7.37 (7.31, 7.41), P<0.05]. Although PPV improves the patients' oxygenation, the associated incidence of hyperoxia exceeds 33%. Down-regulate FiO2 more sharply after PPV is necessary, if oxygenation conditions permit. PPV may alleviate the acidosis associated with permissive hypercapnia in ARDS patients treated with lung protective ventilation strategy (LPVS).

Dynamic evaluation of the pulmonary protective effects of prone position ventilation via respiratory mechanics for patients with moderate to severe acute respiratory distress syndrome.

BackgroundPatients with moderate to severe acute respiratory distress syndrome (ARDS) have been recommended to receive prone position ventilation (PPV). However, the dynamic changes in respiratory mechanics during PPV and their relationship with the prognosis have not been sufficiently evaluated. In addition, the impact of using neuromuscular blocking agents (NMBAs) during PPV on respiratory mechanics is not clear enough. Thus, the study aims to investigate the above-mentioned issues.MethodsA prospective cohort study was conducted on 22 patients with moderate to severe ARDS who received PPV in the intensive care unit (ICU) of the First Affiliated Hospital of Guangzhou Medical University. A multifunctional gastric tube was used to measure the patients’ respiratory mechanics during supine position ventilation (SPV), early PPV (PPV within 4 h of initiation), and middle/late PPV (more than 6 h after the initiation of PPV). Longitudinal data were analyzed with generalized estimating equations (GEE).ResultsCompared with SPV, the esophageal pressure swings (ΔPes) measured during the PPV was significantly higher (SPV 7.46 vs. early PPV 8.00 vs. middle/late PPV 8.30 cmH2O respectively; PSPV vs. middle/late PPV =0.025<0.05). A stratified analysis by patients’ outcome showed that the peak airway pressure (Ppeak), ΔPes and respiration rate (RR) in the death group were significantly higher than survival group. On the contrary, the tidal volume (Vt), diaphragmatic electromyogram (EMGdi) and PaO2/FiO2 ratio (PFR) in the death group were significantly lower than survival group. Notably, the ΔPes and transpulmonary driving pressure (DPL) were significantly lower in the patients treated with NMBAs (7.08 vs. 8.76 cmH2O ΔPes; P<0.01), (14.82 vs. 18.08 cmH2O DPL; P<0.001).ConclusionsDuring the transition from SPV to early PPV and then to middle/late PPV, the ΔPes in the PPV were greater than SPV and it fluctuated within a normal range while oxygenation improved significantly in all patients. The Ppeak, ΔPes and RR in the death group were significantly higher than survival group. When NMBAs were used, the ΔPes, inspiratory transpulmonary pressure (PLei), driving pressure (DP) and DPL were significantly decreased, suggesting that the rational combination of NMBAs and PPV may exert a synergistic protective effect on the lungs.

Effect of prone position ventilation on right heart function in patients with acute respiratory distress syndrome.

Acute respiratory distress syndrome (ARDS) is a severe respiratory disease with a high mortality rate. It is characterized by acute onset of pulmonary edema, hypoxemia, and the need of mechanical ventilation. As the primary treatment, ventilation has been considered effective in treating patients with ARDS. Recently, numerous studies have shown that prone position ventilation demonstrates more efficacy compared with traditional supine position. However, the potential impact of the non-physiological prone position on patients remains unclear. Current study aims to evaluate the effect of prone position ventilation on right heart function in ARDS patients. Following Berlin Diagnostic Criteria, 80 eligible patients were recruited and randomly assigned into prone position ventilation group and supine position ventilation group. Different ventilation methods were implemented in these two groups. Both positions showed the beneficial effects, as evidenced by decreased PV score and APACHE II score, enhanced blood gas index and right heart function parameters, and the prognosis analysis. However, compared with those receiving SPV treatment, the patients demonstrated greater benefits from PPV treatment, with significant differences in PV score (p < 0.01) and APACHE II score (p < 0.001), blood gas index such as PAPm (p < 0.05), and right heart function indicators (p < 0.05). Prone position mechanical ventilation is more beneficial than supine position ventilation in improving the blood gas status of patients with moderate to severe ARDS, and it is more helpful to reduce the load on the right heart and promote the recovery of patients.

Prone versus Supine Position Ventilation in Adult Patients with Acute Respiratory Distress Syndrome: A Meta-Analysis of Randomized Controlled Trials.

The purpose of this meta-analysis was to compare the efficacy and safety of prone versus supine position ventilation for adult acute respiratory distress syndrome (ARDS) patients. The electronic databases of PubMed, Embase, and the Cochrane Library were systematically searched from their inception up to September 2020. The relative risks (RRs) and weighted mean differences (WMDs) with corresponding 95% confidence intervals (CIs) were employed to calculate pooled outcomes using the random-effects models. Twelve randomized controlled trials that had recruited a total of 2264 adults with ARDS were selected for the final meta-analysis. The risk of mortality in patients who received prone position ventilation was 13% lower than for those who received supine ventilation, but this effect was not statistically significant (RR: 0.87; 95% CI: 0.75–1.00; P = 0.055). There were no significant differences between prone and supine position ventilation on the duration of mechanical ventilation (WMD: −0.22; P = 0.883) or ICU stays (WMD: –0.39; P = 0.738). The pooled RRs indicate that patients who received prone position ventilation had increased incidence of pressure scores (RR: 1.23; P = 0.003), displacement of a thoracotomy tube (RR: 3.14; P = 0.047), and endotracheal tube obstruction (RR: 2.45; P = 0.001). The results indicated that prone positioning during ventilation might have a beneficial effect on mortality, though incidence of several adverse events was significantly increased for these patients.

Lung and chest wall mechanics in patients with acute respiratory distress syndrome, expiratory flow limitation, and airway closure.

Tidal expiratory flow limitation (EFL), which may herald airway closure (AC), is a mechanism of loss of aeration in ARDS. In this prospective, short-term, two-center study, we measured static and dynamic chest wall (Est,cw and Edyn,cw) and lung (Est,L and Edyn,L) elastance with esophageal pressure, EFL, and AC at 5 cmH2O positive end-expiratory pressure (PEEP) in intubated, sedated, and paralyzed ARDS patients. For EFL determination, we used the atmospheric method and a new device allowing comparison of tidal flow during expiration to PEEP and to atmosphere. AC was validated when airway opening pressure (AOP) assessed from volume-pressure curve was found greater than PEEP by at least 1 cmH2O. EFL was defined whenever flow did not increase between exhalation to PEEP and to atmosphere over all or part of expiration. Elastance values were expressed as percentage of normal predicted values (%N). Among the 25 patients included, eight had EFL (32%) and 13 AOP (52%). Between patients with and without EFL Edyn,cw [median (1st to 3rd quartiles)] was 70 (16-127) and 102 (70-142) %N (P = 0.32) and Edyn,L338 (332-763) and 224 (160-275) %N (P < 0.001). The corresponding values for Est,cw and Est,L were 70 (56-88) and 85 (64-103) %N (P = 0.35) and 248 (206-348) and 170 (144-195) (P = 0.02), respectively. Dynamic EL had an area receiver operating characteristic curve of 0.88 [95% confidence intervals 0.83-0.92] for EFL and 0.74[0.68-0.79] for AOP. Higher Edyn,L was accurate to predict EFL in ARDS patients; AC can occur independently of EFL, and both should be assessed concurrently in ARDS patients.NEW & NOTEWORTHY Expiratory flow limitation (EFL) and airway closure (AC) were observed in 32% and 52%, respectively, of 25 patients with ARDS investigated during mechanical ventilation in supine position with a positive end-expiratory pressure of 5 cmH2O. The performance of dynamic lung elastance to detect expiratory flow limitation was good and better than that to detect airway closure. The vast majority of patients with EFL also had AC; however, AC can occur in the absence of EFL.

Efficiency of I-gel supraglottic airway device during mechanical ventilation in supine and lateral decubitus position in obese patient; prospective observational study

ABSTRACT Background I-gel supraglottic airway device has been widely used recently in anesthesia practice as an alternative to endotracheal intubation. However, its safety and feasibility in obese patients are still under investigations. The aim of this work was to evaluate the efficiency of I-gel in supine and lateral position in adult obese (BMI 30–40) mechanically ventilated patients undergoing short surgical procedures (60 − 120 min). Methods Prospective observational study was conducted at Kasr Alainy Hospital. A total of 40 obese patients with body mass index 30–40 aged between 20 and 60 years, American Society of Anesthesiologists class II & III scheduled for elective surgeries were enrolled in one group. We used the I-gel in supine position and lateral position in the same patient. The primary outcome was comparison between Oropharyngeal leak airway pressure during controlled ventilation in supine position after insertion of I-gel by 1 min and in lateral position. The secondary outcomes were fiberoptic view , insertion attempts and postoperative upper airway complications Results The leakage pressure required for I-gel did not show statistically significant difference between both supine and lateral positions (33.88 ± 7.34 cmH2O versus 33.10 ± 7.58 cmH2O) respectively. Fiberoptic view ranged between score 2 (8 patients) and score 3 (32 patients) in both supine and lateral position. I-gel was inserted in the first trial in 37 patients, the second trial in two patients and the third trial in one patient. None of the patients experienced postoperative swallowing difficulties, throat pain, hoarseness or postoperative nausea and vomiting. Only two patients (5%) showed blood on I-gel after removal. Conclusion The use of I-gel supraglottic airway device is safe and effective in both supine and lateral position in obese patients under mechanical ventilation with reliable ventilation and no postoperative airway complications. Clinical trial registration clinicaltrial.gov. ID: NCT04119245

Assessment of respiratory drive with esophageal diaphragmatic electromyography in patients with acute respiratory distress syndrome treated with prone position ventilation.

Prone position ventilation (PPV) is an important strategy for patients with severe acute respiratory distress syndrome (ARDS). This prospective study investigated the use of electromyography of the diaphragm (EMGdi) for monitoring respiratory drive in patients with moderate to severe ARDS during long-term PPV. An integrated nostril-gastric feeding tube containing an esophageal electrode and balloon was placed in 14 patients with severe ARDS prior to PPV. EMGdi and trans-pulmonary pressure (∆PL) data were collected before PPV (baseline), every 2 h during PPV, and 2 h after the restoration of supine position ventilation (post-2 h SPV). In ARDS patients, the static compliance of the chest wall was significantly decreased after PPV. EMGdi levels were slightly lower in the early, middle, and late stages of PPV compared with baseline. Patients who received neuromuscular blocker experienced a greater drop in EMGdi from baseline than those who did not. For ARDS patients, EMGdi was slightly decreased after prolonged PPV. This is contrary to the change in diaphragm electromyography during normal body position changes. Monitoring EMGdi regularly during PPV in ARDS patients is feasible and can be used as a reference for lung protective ventilation strategies.

Effects of Positive End-Expiratory Pressure and Spontaneous Breathing Activity on Regional Lung Inflammation in Experimental Acute Respiratory Distress Syndrome.

To determine the impact of positive end-expiratory pressure during mechanical ventilation with and without spontaneous breathing activity on regional lung inflammation in experimental nonsevere acute respiratory distress syndrome. Laboratory investigation. University hospital research facility. Twenty-four pigs (28.1-58.2 kg). In anesthetized animals, intrapleural pressure sensors were placed thoracoscopically in ventral, dorsal, and caudal regions of the left hemithorax. Lung injury was induced with saline lung lavage followed by injurious ventilation in supine position. During airway pressure release ventilation with low tidal volumes, positive end-expiratory pressure was set 4 cm H2O above the level to reach a positive transpulmonary pressure in caudal regions at end-expiration (best-positive end-expiratory pressure). Animals were randomly assigned to one of four groups (n = 6/group; 12 hr): 1) no spontaneous breathing activity and positive end-expiratory pressure = best-positive end-expiratory pressure - 4 cm H2O, 2) no spontaneous breathing activity and positive end-expiratory pressure = best-positive end-expiratory pressure + 4 cm H2O, 3) spontaneous breathing activity and positive end-expiratory pressure = best-positive end-expiratory pressure + 4 cm H2O, 4) spontaneous breathing activity and positive end-expiratory pressure = best-positive end-expiratory pressure - 4 cm H2O. Global lung inflammation assessed by specific [F]fluorodeoxyglucose uptake rate (median [25-75% percentiles], min) was decreased with higher compared with lower positive end-expiratory pressure both without spontaneous breathing activity (0.029 [0.027-0.030] vs 0.044 [0.041-0.065]; p = 0.004) and with spontaneous breathing activity (0.032 [0.028-0.043] vs 0.057 [0.042-0.075]; p = 0.016). Spontaneous breathing activity did not increase global lung inflammation. Lung inflammation in dorsal regions correlated with transpulmonary driving pressure from spontaneous breathing at lower (r = 0.850; p = 0.032) but not higher positive end-expiratory pressure (r = 0.018; p = 0.972). Higher positive end-expiratory pressure resulted in a more homogeneous distribution of aeration and regional transpulmonary pressures at end-expiration along the ventral-dorsal gradient, as well as a shift of the perfusion center toward dependent zones in the presence of spontaneous breathing activity. In experimental mild-to-moderate acute respiratory distress syndrome, positive end-expiratory pressure levels that stabilize dependent lung regions reduce global lung inflammation during mechanical ventilation, independent from spontaneous breathing activity.

HFOV with prone ventilation in pediatric severe ARDS, a case series from a tertiary care hospital

Severe ARDS in pediatrics is a life-threatening illness associated with significant morbidity and mortality, which often needs use of rescue ventilatory and non-ventilatory strategies. Despite non-encouraging results of HFOV in adults, its use still continues in pediatric population. We present three cases of primary severe ARDS, where oxygenation was refractory to conventional ventilation, prone positioning with conventional ventilation and to HFOV ventilation in supine position. In all these three cases oxygenation markedly improved with HFOV ventilation with prone positioning. Out of the three, two patients survived and one succumbed during the course of illness. We would like to hypothesize that prone positioning is feasible on HFOV and can be used as a rescue strategy for improving oxygenation and outcome when other measures fail.

Lung aeration and ventilation after percutaneous tracheotomy measured by electrical impedance tomography in non-hypoxemic critically ill patients: a prospective observational study

BackgroundPercutaneous dilatational tracheotomy (PDT) may lead to transient impairment of pulmonary function due to suboptimal ventilation, loss of positive end-expiratory pressure (PEEP) and repetitive suction maneuvers during the procedure. Possible changes in regional lung aeration were investigated using electrical impedance tomography (EIT), an increasingly implied instrument for bedside monitoring of pulmonary aeration.MethodsWith local ethics committee approval, after obtaining written informed consent 29 patients scheduled for elective PDT under bronchoscopic control were studied during mechanical ventilation in supine position. Anesthetized patients were monitored with a 16-electrode EIT monitor for 2 min at four time points: (a) before and (b) after initiation of neuromuscular blockade (NMB), (c) after dilatational tracheostomy (PDT) and (d) after a standardized recruitment maneuver (RM) following surgery, respectively. Possible changes in lung aeration were detected by changes in end-expiratory lung impedance (Δ EELI). Global and regional ventilation was characterized by analysis of tidal impedance variation.ResultsWhile NMB had no detectable effect on EELI, PDT led to significantly reduced EELI in dorsal lung regions as compared to baseline, suggesting reduced regional aeration. This effect could be reversed by a standardized RM. Mean delta EELI from baseline (SE) was: NMB − 47 ± 62; PDT − 490 ± 180; RM − 89 ± 176, values shown as arbitrary units (a.u.). Analysis of regional tidal impedance variation, a robust measure of regional ventilation, did not show significant changes in ventilation distribution.ConclusionThough changes of EELI might suggest temporary loss of aeration in dorsal lung regions, PDT does not lead to significant changes in either regional ventilation distribution or oxygenation.

I-gel versus Air-Q for airway maintenance during general anaesthesia with controlled ventilation in paediatrics

Background In the last few years, a number of supraglottic airway devices have been introduced in the clinical practice of airway management, trying to offer a simple and effective alternative to the endotracheal intubation. These devices are designed to overcome the disadvantages of endotracheal intubation such as soft tissue injury and exaggerated haemodynamic response. Purpose The aim of the present study was to compare between the I-gel and the Air-Q intubating laryngeal airway as alternative supraglottic airway devices during general anaesthesia with controlled ventilation in paediatrics. Patients and methods Sixty ASA grade I and II children, aged 3–6 years, and scheduled to undergo elective surgery under general anaesthesia with controlled ventilation in supine position were randomly categorized into two equal groups (30 patients each): group I, in which the I-gel was used to maintain a patent airway during anaesthesia; and group II, in which Air-Q intubating laryngeal airway was used to maintain a patent airway during anaesthesia. After induction of anaesthesia and muscle relaxation, we measured ease of insertion, time and number of trials to successful insertion, airway sealing pressure, fibrescopic view of the glottis, maintenance success, haemodynamic responses, airway interventional requirements and any other complications. Conclusion This study showed that both supraglottic airway devices are suitable for positive pressure ventilation with high success rates in children undergoing elective surgeries. It was found that the I-gel has a shorter time of insertion and a higher airway sealing pressure, whereas Air-Q has a better fibrescopic view of the glottis.

Prone position ventilation in Acute Respiratory Distress Syndrome: An overview of the evidences.

The past two decades have seen five major and multiple small trials comparing prone and supine position ventilation in acute respiratory distress syndrome (ARDS). This article attempts to review the evidences for prone-positioning in ARDS.

Effect of postural changes on the mechanical ventilation in patients with acute respiratory distress syndrome

Objective To compare the effect of postural changes on the mechanical ventilation in patients with acute respiratory distress syndrome （ ARDS ） .Methods A total of 40 ARDS patients with mechanical ventilation from January 2010 to December 2012 and without contraindications for mechanical ventilation in the prone position were selected , who were divided into the prone position ventilation group and the supine position ventilation group by random number table method , with 20 patients in each group .The changes of vital signs and arterial blood gas before and after mechanical ventilation were compared between the two groups, including the mean airway pressure , plateau pressure and airway resistance three days after treatment . Also, the mechanical ventilation time and the time taken to stay emergency room were compared between the two groups.Results Compared with before treatment , the T, P, MAP and PaCO2 after treatment all decreased in the two groups, with statistically significant differences （P＜0.01）;the PETCO2, pH, PaO2, PaO2/FiO2 after treatment all increased in the two groups , with statistically significant differences （P＜0.01）.There were no statistically significant differences between the two groups in T , P, PETCO2 , MAP, pH, PaO2 , PaCO2 （ P＞0.05）.The PaO2/FiO2 in the prone position ventilation group was （282 ±177;22） three days after treatment , which was higher than that of （245 ±177;21） in the supine position ventilation group three days after treatment , and the difference was statistically significant （t=6.18, P＜0.01）.The mean airway pressure, plateau pressure and airway resistance three days after treatment was （6.8 ±177;0.5） cmH2O, （17.1 ±177;2.0） cmH2O and （14.9 ±177; 1.2）cmH2O/（L±183; s） in the prone position ventilation group, respectively, which was （8.5 ±177;0.9） cmH2O, （20.6 ±177;2.3）cmH2O and （21.1 ±177;0.8）cmH2O/（L±183; s） in the supine position ventilation group , respectively, and the differences were statistically significant （t =7.38, 5.13, 18.83, respectively;P ＜0.01）.The mechanical ventilation time and the time taken to stay emergency room in the prone position ventilation group were shorter than those in the supine position ventilation , and the differences were statistically significant （ t=9.007, 6.379, respectively;P ＜0.01）.Conclusions Prone position ventilation can be more effective in improving oxygenation index and redressing hypoxemia , and has relatively little impact on the patients ’ airway, which is an ideal position of mechanical ventilation . Key words: Respiratory distress syndrome,adult; Position; Mechanical ventilation

Effectiveness of Prone Ventilation in patients with Acute Respiratory Distress Syndrome: a systematic review.

Review question/objective The objective of this review is to identify and synthesize the best available evidence related to the benefits of prone ventilation in critically ill adult patients with Acute Respiratory Distress Syndrome. More specifically, the objectives are to identify: the effectiveness of prone positioning in critically ill adult patients requiring mechanical ventilation due to Acute Respiratory Distress Syndrome on mortality, oxygenation and duration of mechanical ventilation. Inclusion criteria Types of participants This review will consider studies that include patients older than 18 years, regardless of gender or ethnicity, who are critically ill, admitted to ICU for Acute Lung Injury or Acute Respiratory Distress Syndrome as defined by European-American Consensus4 and have failed conventional modes of ventilation. Studies with control group who did not receive tidal volume of 6-8 mL/Kg IDBW ventilation as per ARDS protocol will be excluded. Types of intervention(s)/phenomena of interest This review will consider as the intervention of interest, the mechanical ventilation in prone position as compared with the mechanical ventilation in supine position. Types of outcomes The primary outcome of interest is reported mortality. The secondary outcomes of interest are: improvement in oxygenation measured as ratio of arterial partial pressure of oxygen over fraction of inhaled oxygen (PaO2/FiO2); duration of mechanical ventilation measured as number of days that the patient required mechanical ventilation until discharge from the hospital.

The feasibility of selective left lower lobar blockade based on Coopdech endobronchial blocker tube

Objective To observe the feasibility of selective left lower lobar blockade by Coopdech endobronchial blocker tube (BB)in patients with normal spirometry during left-sided lower esophageal surgery, and the effects on dynamic lung compliance (Cdyn), peak inspiratory airway pressure(Ppeak)and arterial oxygenation. Methods 30 patients(aged 44-64 yr)scheduled for left-sided lower esophageal surgery were allocated randomly to two groups: Group BB or group double-lumen endobronchial tubes (DLT)(n=15). Anesthesia was induced and maintained with Propofol by target controlled infusion, administered sufentanil and cisatracurium intravenously if needed. The left-sided DLT was placed in the DLT group and an 8.0-mm internal diameter single-lumen endotracheal tube was used in the BB group and 9 French Coopdech blocker was advanced into the left lower lobar bronchus with the guidance of a fiberoptic bronchoscope in the latter group. The variables recorded were Ppeak, Cdyn and arterial blood gas analyses data at four surgical times: 20 minutes after two-lung ventilation in supine position (T_1), 20 minutes after initiation of one-lung ventilation or selective left lower lobar blockade by inflating BB balloons in right lateral decubitus position (T_2), total collapse of left lung or left lower lobe after the pleura was opened(T_3) and before tracheal extubation(T_4). Tidal volume and respiratory rate were kept constant at each time. Once the pleura were opened, the effectiveness of lung collapse was evaluated by the surgeon who performed the surgery. Chest radiograph and arterial blood gas analyses were performed in the first postoperative day. Results The groups were comparable with regard to rank of surgical exposure; pH, PaCO_2 from T_1 to T_4; Cdyn, Ppeak, PaO_2 at T_1. Significant trends were found toward a higher decrease in Ppeak [ (17.7±2.9) cm H_2O vs (21.7±3.6) cm H_2O in T_2, (17.8±3,2) cm H_2O vs (22.6±2.6) cm H_2O in T_3,(14.8±2.2) cm H_2O vs(16.8±1.8) cm H_2O in T_4, respectively] and a better improvement in cdyn[ (36±9) ml/cm H_2O vs (24±6) ml/cm H_2O in T_2, (37±10) ml/cm H_2O vs (23±6) ml/cm H_2O in T_3, (44±8) ml/cm H_2O vs (35±12) ml/cm H_2O in T_4, respectively], PaO_2[ (220±56) mm Hg vs (146±38) mm Hg in T_2, (188±57) mm Hg vs (140±36) mm Hg in T_3, (208±24) mm Hg vs(157±33) mm Hg in T_4, respectively] during the operation with the BB compared to DLT (P<0.05 or <0.01). No lobe collapse was observed in the postoperative period in BB group, but 1 patients of DLT group was found left lower lobe atelectasis. A better postoperative arterial oxygenation was shown in BB group (P<0.01). Conclusion Selective left lower lobar blockade achieved by Coopdech endobronchial blocker tube during left-sided esophageal surgery provides a good surgical exposure, together with a lower intraoperative peak inspiratory airway pressure, and better arterial oxygenation and dynamic lung compliance. Key words: Selective lobar blockade; Endobronchial blocker tube; Double-lumen endobronchial tube; One lung ventilation; Dynamic lung compliance; Peak inspiratory airway pressure

Comparative study between I-gel, a new supraglottic airway device, and classical laryngeal mask airway in anesthetized spontaneously ventilated patients.

Objective:To compare two different supraglottic airway devices, the laryngeal mask airway (LMA) and the I-gel, regarding easiness of insertion of the device, leak pressure, gastric insufflation, end tidal CO2, oxygen saturation, hemodynamic and postoperative complications in anesthetized, spontaneously ventilated adult patients performing different non-emergency surgical procedures.Materials and Methods:The study was carried out as a prospective, randomized, clinical trial among 80 patients who underwent different surgical procedures under general anesthesia with spontaneous ventilation in supine position. They were equally randomized into two groups: I-gel and LMA groups. Both the devices were compared with regard to heart rate, arterial BP, SPO2, end-tidal CO2, number and duration of insertion attempts, incidence of gastric insufflation, leak pressure and airway assessment after removal of the device.Results:No statistically significant difference was reported between both the groups, regarding heart rate, arterial BP, SPO2 and end-tidal CO2. The mean duration of insertion attempts was 15.6±4.9 seconds in the I-gel group, while it was 26.2±17.7 seconds in the LMA group. The difference between both the groups regarding duration of insertion attempts was statistically significant (P=0.0023*), while the number of insertion attempts was statistically insignificant between both the study groups (P>0.05). Leak pressure was (25.6±4.9 vs. 21.2±7.7 cm H2O) significantly higher among studied patients of the I-gel group (P=0.016*) and the incidence of gastric insufflation was significantly more with LMA group 9 (22.5%) vs. I-gel group (5%) (P=0.016).Conclusion:Both LMA and I-gel do not cause any significant alteration in the hemodynamic status of the patients, end tidal CO2, and SPO2. The postoperative complications were not significantly different except nusea and vomiting was statistically significant higher in LMA group (P=0.032). among both LMA and I-gel patients. Insertion of I-gel was significantly easier and more rapid than insertion of LMA. Leak pressure was significantly higher with I-gel than LMA and thus incidence of gastric insufflation was significantly lower with I-gel.