Arterial oxygenation during one lung ventilation

Purpose  To compare the effects of isoflurane and sevoflurane on artenal oxygenation and middle cerebral artery blood flow velocity during one lung ventilation. Methods  This was a randomized, crossover study in 20 patients undergoing thoracotomy for oesophageal cancer and scheduled for long term one lung ventilation (OLV). They were randomized to one of two groups: group A. firstly isoflurane was administered followed by sevoflurane, and then isoflurane was resumed; group B. the order of the administration was reversed. Artenal blood gas samples were drawn at the start of OLV, 30 and 60 min after the initiation of OLV and the end of OLV (the change of volatile anesthetics was done 30 and 60 min after the start of OLV). Middle cerebral artery (MCA) was monitored continuously with the probe positioned over the temporal bone window. This probe transmitted 2 MHZ wave Doppler signals. Time-averaged MCA blood flow velocity was calculated from the signals. Results  The PaO values decreased 30 min after the start of OLV (364.4 ±33.4 mmHg vs 179.0 ± 19.5, and 338.7 ± 24.8 mmHg vs 139.7 ± 19.9 in groups A and B respectively), but there was no difference between the groups. Blood flow velocity of MCA did not change after the start of OLV (53.1 ± 3.2, 55.9 ± 3.0. 56.4 ± 2.4, and 54.1 ± 1.9 vs 50.8 ± 2.1, 50.7 ± 2.4, 53.7 ± 1.5, 50.8 ± 2.2 cm · sec⁻¹ in groups A and B respectively): there was no difference between the groups. (P < 0.05). Conclusion  In clinical practice, the selection of either isoflurane and sevoflurane for OLV was of no difference in terms of the artena 1 blood oxygenation. With both agents MCA blood flow velocity was maintained during OLV.

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Résumé Objectif  Comparer les effets de l’isoflurane et du sévoflurane sur l’oxygénation arténelle et la vélocité du débit de l’artère cérébrale moyenne pendant la ventilation unipulmonaire. Méthodes  Cette étude aléatoire avec croisement regroupait 20 sujets thoracotomisés pour un cancer de l’oesophage et programinés pour une ventilation unipulmonaire (VUP) prolongée. Ils ont été répartis au hasard en deux groupes: le groupe A recevait de l’isoflurane suivi du sévoflurane et de l’isoflurane à nouveau; dans le groupe B, l’ordre des agerts était inversé. Des échantillons de sang étaient prélevés pour la gazométne arténelle au début de la VUP, 30 et 60 min plus tard, et à la fin de la VUP (l’échange d’anesthésique volatil survenait 30 et 60 min après l’initiation de la VUP) Un capteur placé sur l’os temporal permettait de monitorer l’artère cérébrale moyenne (ACM) en continu par la transmission d’ondes Doppler de 2 MHZ Ces signaux ont servi au calcul de la moyenne de la vélocité du débit de l’ACM en fonction du temps. Résultats  Les valeurs de la PaO₂ ont diminué 30 min après le début de la VUP (respectivement dans les groupes A et B; 364,4 ± 33,4 mmHg à 179,0 ± 19,5 et 338,7 ± 24,8 mmHg à 139,7 ± 19,9) mais sans différence intergroupe La vélocité sanguine de l’ACM n’a pas changé après la mise en marche de la VUP (respectivement dans les groupes A et B; 53,1 t 3,2; 55,9 ± 3,0: 56,4 ± 2,4 et 54,1 ± 1,9 vs 50,8 ± 2,1; 50,7 ± 2,4; 53,7 ± 1,5: 50,8 ± 2,2 cm · s⁻¹); il n’y a pas eu de différence entre les groupes (P < 0,05). Conclusion  En clinique, le choix de l’isoflurane ou du sévoflurane pour la VUP n’influence pas l’oxygénation artérielle Le débit sanguin de l’ACM se maintient pendant la VUP avec l’un et l’autre des agents.

     

Alarming hypoxemia during one-lung ventilation in a patient with respiratory bronchiolitis-associated interstitial lung disease

PURPOSE: To report a patient with respiratory bronchiolitis-associated interstitial lung disease (RB-ILD) who developed severe hypoxemia during one-lung ventilation (OLV). CLINICAL FEATURES: A 27-yr-old female, ex-smoker presented with productive cough and dyspnea of 18-month duration. The chest x-ray revealed diffuse abnormalities involving both lungs consisting of interstitial emphysema with irregular shadowing. Preoperative PaO(2) was 88 mmHg and pulmonary function tests showed moderate obstructive disease. The patient underwent right open lung biopsy. After induction of anesthesia, a left double lumen tube was inserted and its position verified with auscultation and fibreoptic bronchoscopy. Upon initiation of OLV, the patient developed severe hypoxemia and the PaO(2) dropped from 500 mmHg during two-lung ventilation (TLV) to 50 mmHg. Hypoxemia was readily corrected by resuming TLV. CONCLUSION: The severe hypoxemia during OLV in this patient with RB-ILD may be attributed to impaired hypoxic pulmonary vasoconstriction. Other causes were not excluded. Caution is warranted when initiating OLV in these patients.     

Approaches to hypoxemia during single-lung ventilation

Modern techniques to isolate the lungs, coupled with accurate continuous non-invasive monitoring, have made single-lung ventilation safe and easy to perform. Most patients maintain an adequate arterial oxygen tension during single-lung ventilation. In order to maximize oxygenation, efforts are directed towards optimizing perfusion and ventilation to the ventilated lung or increasing the oxygen content of blood returning from the collapsed lung.     

Smoking is a risk factor for incisional hernia

HYPOTHESIS: A number of risk factors for incisional hernia have been identified, but the pathogenesis remains unclear. Based on previous findings of smoking as a risk factor for wound complications and recurrence of groin hernia, we studied whether smoking is associated with incisional hernia. DESIGN: Cohort study. Clinical follow-up study for incisional hernia 33 to 57 months following laparotomy for gastrointestinal disease. Variables predictive for incisional hernia were assessed by multiple regression analysis. SETTING: Department of Surgery, Bispebjerg Hospital, University of Copenhagen, Copenhagen, Denmark. PATIENTS: All 916 patients undergoing laparotomy from 1997 through 1998. Surgeons performed clinical examination in 310 patients; patients who failed to meet for examination, died, or were lost to follow-up were excluded. MAIN OUTCOME MEASURES: Thirty-four variables related to patient history, preoperative clinical condition, operative severity and findings, and the surgeon's training. RESULTS: The incidence of incisional hernia was 26% (81/310). Smokers had a 4-fold higher risk of incisional hernia (odds ratio [OR], 3.93 [95% confidence interval (CI), 1.82-8.49]) independent of other risk factors and confounders. Relaparotomy was the strongest factor associated with hernia (OR, 5.89 [95% CI, 1.78-19.48]). Other risk factors were postoperative wound complications (OR, 3.91 [95% CI, 1.99-7.66]), age (OR, 1.04 [95% CI, 1.02-1.06]), and male sex (OR, 2.17 [95% CI, 1.21-3.91]). CONCLUSION: Smoking is a significant risk factor for incisional hernia in line with relaparotomy, postoperative wound complications, older age, and male sex.     

Arterial oxygenation during one lung ventilation in obese patients

To test the hypothesis that arterial oxygenation during one lung ventilation (OLV) is impaired more in obese patients than in non-obese control patients, we performed consecutive measurements of arterial oxygen tension (PaO2) during OLV in 48 patients scheduled for pulmonary lobectomy. Minimum value of PaO2 during OLV was significantly less in 16 obese patients [body mass index (BMI) > 25] compared to 32 control patients (BMI < 25). Moreover, PaO2 value of left lung ventilation was significantly less than the value of right lung ventilation in obese patients while the difference was not statistically significant in the control group.     

单肺通气时不同潮气量对呼吸功能的影响

目的 研究单肺通气(OLV)时不同潮气量时的综合评价.方法 60例右侧开胸左侧卧位非右肺全肺切除患者,ASA Ⅰ或Ⅱ级,随机分为A、B、C三组,每组20例.全麻后双肺通气(TLV)潮气量(VT)均为10 ml/kg,RR为12次/分,吸呼比(I∶E)为1∶2.OLV期间A组VT6ml/kg,B组VT 8 ml/kg,C组VT10 ml/kg,分别于OLV前(T1)及OLV后10 min(T2)、20 min(T3)、30 min(T4)采集动脉血及中心静脉血行实验室检查,并计算肺内分流量(Qs/Qt),同时监测气道压力并计算动态肺顺应性(Cdyn),监测PETCO2,并在T4时对三组患者进行综合评价.结果 与T1时比较,T2～T4时三组PaO2、Cdyn降低,PaCO2、Qs/Qt、Pmax、Pmean明显升高(P＜0.05).与B组比较,T2～T4时C组PaO2降低,Pmax、Pmean明显升高(P＜0.05).T4时B组综合评价最好.结论 OLV期间采用B组VT8 ml/kg相对较好.     

High-frequency percussive ventilation during surgical bronchial repair in a patient with one lung

We report the case of a patient that had undergone a left pneumonectomyduring which a double-lumen tube was used and an undetectedright bronchial laceration occurred. After diagnosis the patientunderwent a second operation to repair the tear. The role ofhigh-frequency percussive ventilation in enabling adequate gasexchange during the bronchial repair is described and discussed.     

Prediction of hypoxemia and mechanical ventilation after lung resection for cancer.

BACKGROUND: Hypoxemia usually occurs after thoracotomy, and respiratory failure represents a major complication. METHODS: To define predictive factors of postoperative hypoxemia and mechanical ventilation (MV), we prospectively studied 48 patients who had undergone lung resection. Preoperative data included, age, lung volume, force expiratory volume in one second (FEV1), predictive postoperative FEV1 (FEV1ppo), blood gases, diffusing capacity, and number of resected subsegments. RESULTS: On postoperative day 1 or 2, hypoxemia was assessed by measurement of PaO2 and alveolar-arterial oxygen tension difference (A-aDO2) in 35 nonventilated patients breathing room air. The other patients (5 lobectomies, 9 pneumonectomies) required MV for pulmonary or nonpulmonary complications. Using simple and multiple regression analysis, the best predictors of postoperative hypoxemia were FEV1ppo (r = 0.74, p < 0.001) in lobectomy and tidal volume (r = 0.67, p < 0.01) in pneumonectomy. Using discriminant analysis, FEV1ppo in lobectomy and tidal volume in pneumonectomy were also considered as the best predictive factors of MV for pulmonary complications. CONCLUSIONS: These results suggest that the degree of chronic obstructive pulmonary disease in lobectomy and impairment of preoperative breathing pattern in pneumonectomy are the main factors of respiratory failure after lung resection.     

Non-invasive ventilation in prone position for refractory hypoxemia after bilateral lung transplantation

Abstract:  Temporary graft dysfunction with gas exchange abnormalities is a common finding during the postoperative course of a lung transplant and is often determined by the post-reimplantation syndrome. Supportive measures including oxygen by mask, inotropes, diuretics, and pulmonary vasodilators are usually effective in non-severe post-reimplantation syndromes. However, in less-responsive clinical pictures, tracheal intubation with positive pressure ventilation, or non-invasive positive pressure ventilation (NIV), is necessary. We report on the clinical course of two patients suffering from refractory hypoxemia due to post-reimplantation syndrome treated with NIV in the prone and Trendelenburg positions. NIV was well tolerated and led to resolution of atelectactic areas and dishomogeneous lung infiltrates. Repeated turning from supine to prone under non invasive ventilation determined a stable improvement of gas exchange and prevented a more invasive approach. Even though NIV in the prone position has not yet entered into clinical practice, it could be an interesting option to achieve a better match between ventilation and perfusion. This technique, which we successfully applied in lung transplantation, can be easily extended to other lung diseases with non-recruitable dorso-basal areas.     

Case of transfusion-related acute lung injury associated with severe intraoperative hypoxemia

A 39-year-old woman, undergoing debridement and flap reconstruction for a soft tissue infection in an upper limb, developed transfusion-related acute lung injury (TRALI) and hypoxemia after an intraoperative transfusion. Perioperatively, she received 8 units of packed red blood cells (RBCs) and 5 units of fresh frozen plasma. Shortly thereafter, hemoglobin oxygen saturation decreased from 100% to 94%, as measured with a pulse oximeter. Chest radiography showed diffuse bilateral pulmonary edema without heart enlargement and echocardiography revealed normal cardiac function. Based on the findings and clinical course, we diagnosed TRALI, started respiratory support with positive endexpiratory pressure ventilation, and administrated sivelestat and dopamine. Hemodynamics and pulmonary vascular permeability were assessed using transpulmonary thermodilution method (PiCCO, PULSION Medical Systems), which enabled determination of cardiac output and extravascular lung water index (EVLWI). EVLWI is useful for quantification of pulmonary edema, a beneficial indicator of cardiorespiratory management. Pulmonary edema improved and the trachea was extubated 34 hours after surgery. Antibodies against HLA were detected in the RBC donor serum sample, and a crossmatch test between the patient lymphocytes and donor serum was positive. We concluded that perioperative transfusion of blood components has a potential to provoke serious TRALI.     

Heart rate to arterial pressure impulse response during one lung ventilation

BACKGROUND: Although one lung ventilation (OLV) is commonly used, little is known about the modulation of the autonomic nervous system with OLV while under general anesthesia. As the frequency domain and time domain analyses are powerful analytic tools, we investigated their modulation during OLV. METHODS: Patients undergoing thoracic surgery were classified into two groups: those who did (group A, n=8) and those who did not (group N, n=8) receive atropine. After a double lumen tube was placed endotracheally, mechanical ventilation of both lungs (BLV) was established at 18 min(-1) while under isoflurane anesthesia. Electrocardiogram, systolic arterial pressure (SAP), and inspiratory flow (Finsp) were digitally recorded as follows: awake before anesthesia; BLV after anesthesia; BLV after intravenous 10 microg kg(-1) of atropine (group A) or not (group N); left OLV; and right OLV. Power spectral analyses of heart rate (HR) and SAP were computed by determining low-(LF, 0.04-0.15 Hz) and high-frequency (HF, 0.15-0.40 Hz) components, and impulse response analysis was executed among HR, SAP, and Finsp. Impulse responses were assessed by the maximum values in the time domain. RESULTS: In frequency domain analysis, atropine depressed LF and LF/HF but not HF in HR variability, while no difference was observed between right OLV and left OLV. The heart rate to SAP impulse response was maintained at a significantly higher level in group A than in group N (905+/-360 vs. 425+/-375 mmHg beats(-1)min(-1)) at right OLV. A significant difference was also observed between left and right OLV within group N. CONCLUSION: Impulse response analysis demonstrated that there is a greater effect on autonomic nervous system modulation during right OLV than in left OLV, which mainly results from a parasympathetic neural linkage origin.