iNO as Salvage Treatment of Hypoxemia After TAAD Surgery

Study Overview
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Brief Summary
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The purpose of this study was to clarify the possible mechanism of hypoxemia after surgical treatment of type A acute aortic dissection and the possible mechanism of the treatment role of inhaled nitric oxide in refractory hypoxemia.

Detailed Description
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The investigators' previous study has stressed that inhaled nitric oxide therapy might play an ameliorative role in patients with refractory hypoxemia after surgical treatment of type A acute aortic dissection. The possible reason might be the decreasing of intrapulmonary shunt because previous studies showed that inhaled nitric oxide could decrease intrapulmonary shunt by selectively dilating the pulmonary vessels in ventilated areas. As a result, the investigators designed this observational study to calculate the intrapulmonary shunt before and after inhaled nitric oxide therapy. Intrapulmonary shunt was calculated from oxygen content (CO2) of different sites ( artery, mixed venous, alveolar capillary) by Fick equation:(CaO2-CcO2)/(CvO2-CcO2). A FiO2 of 1.0 and tidal volume of 6 8 ml/kg were chosen. Oxygen content was calculated from hemoglobin (Hb), oxygen saturation (SO2) and oxygen partial pressure (PO2) by the following equation: CO2 = 1.34*Hb*SO2 + 0,0031*PO2. PaO2, SaO2, PvO2 and SvO2 were measured from arterial and mixed venous blood samples taken from the radial arterial catheter and from the pulmonary artery catheter. ScO2 was estimated to be 1.0 with a FiO2 of 100%. PcO2 was considered to be the same as PAO2 (partial pressure of oxygen in the alveoli), and was calculated from the alveolar gas equation with PAO2 = [(atmospheric pressure - 47) * (FiO2)] - PaCO2/0.8.Other variables such as hemodynamic variables from pulmonary artery catheter were also collected.

Official Title
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Inhaled Nitric Oxide as Salvage Treatment of Hypoxemia After Type A Acute Aortic Dissection Surgery (INSTEAD)

Conditions
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Type A Aortic Dissection

Intervention / Treatment
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* Drug: inhaled nitric oxide
* Device: PEEP


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Adult Type A aortic dissection; After surgery; P/F ratio ≤ 200mmHg Exclusion Criteria: Intracardiac shunt; Contradiction of PAC; Chronic pulmonary diseases before surgery; ECMO; Anticipation of death within 48 hours after operation;

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 80 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| PEEP 5<br>post-surgical type A acute aortic dissection patients was ventilated with a PEEP of 5cm H2O, without inhaled nitric oxide | |
| PEEP 10<br>post-surgical type A acute aortic dissection patients was ventilated with a PEEP of 10cm H2O, without inhaled nitric oxide | Drug: inhaled nitric oxide<br>* using of inhaled nitric oxide<br>* Other names: iNO;Device: PEEP<br>* increasing PEEP or decreasing PEEP<br>|
| PEEP 10 +iNO<br>post-surgical type A acute aortic dissection patients was ventilated with a PEEP of 10cm H2O, with inhaled nitric oxide | |
| PEEP 5 +iNO<br>post-surgical type A acute aortic dissection patients was ventilated with a PEEP of 5cm H2O, with inhaled nitric oxide | Drug: inhaled nitric oxide<br>* using of inhaled nitric oxide<br>* Other names: iNO;Device: PEEP<br>* increasing PEEP or decreasing PEEP<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Intrapulmonary shunt with a PEEP of 5 cm H2O | intrapulmonary shunt calculated by Fick equation with a PEEP of 5 cm H2O | 6 to 24 hours after surgery | 
| Intrapulmonary shunt with a PEEP of 10 cm H2O | intrapulmonary shunt calculated by Fick equation with a PEEP of 10 cm H2O | 30 minutes after increasing PEEP to 10cm H2O | 
| Intrapulmonary shunt with a PEEP of 10 cm H2O and inhaled nitric oxide | intrapulmonary shunt calculated by Fick equation with a PEEP of 10 cm H2O and inhaled nitric oxide | 30 minutes after inhaling nitric oxide | 
| Intrapulmonary shunt with inhaled nitric oxide and a PEEP of 5 cm H2O | intrapulmonary shunt calculated by Fick equation with inhaled nitric oxide and a PEEP of 5 cm H2O | 30 minutes after decreasing PEEP to 5cm H2O | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| cardiac output collected from PAC with a PEEP of 5 cm H2O | cardiac output in L/min | 6 to 24 hours after surgery | 
| pulmonary artery pressure collected from PAC with a PEEP of 5 cm H2O | pulmonary artery pressure in mmHg | 6 to 24 hours after surgery | 
| pulmonary artery wedge pressure collected from PAC with a PEEP of 5 cm H2O | pulmonary artery wedge pressure in mmHg | 6 to 24 hours after surgery | 
| cardiac output collected from PAC with a PEEP of 10cm H2O | cardiac output in L/min | 30 minutes after increasing PEEP to 10cm H2O | 
| pulmonary artery pressure collected from PAC with a PEEP of 10 cm H2O | pulmonary artery pressure in mmHg | 30 minutes after increasing PEEP to 10cm H2O | 
| pulmonary artery wedge pressure collected from PAC with a PEEP of 10 cm H2O | pulmonary artery wedge pressure in mmHg | 30 minutes after increasing PEEP to 10cm H2O | 
| cardiac output collected from PAC with a PEEP of 10 cm H2O and inhaled nitric oxide | cardiac output in L/min | 30 minutes after inhaling nitric oxide | 
| pulmonary artery pressure collected from PAC with a PEEP of 10 cm H2O and inhaled nitric oxide | pulmonary artery pressure in mmHg | 30 minutes after inhaling nitric oxide | 
| pulmonary artery wedge pressure collected from PAC with a PEEP of 10 cm H2O and inhaled nitric oxide | pulmonary artery wedge pressure in mmHg | 30 minutes after inhaling nitric oxide | 
| cardiac output collected from PAC with inhaled nitric oxide and a PEEP of 5 cm H2O | cardiac output in L/min | 30 minutes after decreasing PEEP to 5 cm H2O | 
| pulmonary artery pressure collected from PAC with inhaled nitric oxide and a PEEP of 5 cm H2O | pulmonary artery pressure in mmHg | 30 minutes after decreasing PEEP to 5 cm H2O | 
| pulmonary artery wedge pressure collected from PAC with inhaled nitric oxide and a PEEP of 5 cm H2O | pulmonary artery wedge pressure in mmHg, etc | 30 minutes after decreasing PEEP to 5 cm H2O | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Hypoxemia, Type A acute aortic dissection, inhaled nitric oxide