“VOLUME VERSUS PRESSURE CONTROLLED VENTILATION DURING ONE LUNG VENTILATION IN DECORTICATION FOR EMPYEMA THORACIS”

BACKGROUND AND RATIONALE

One-lung ventilation (OLV) during thoracic surgery, in particular, video-assisted thoracic surgery is a standard practice to facilitate surgical exposure, but arterial hypoxemia has been a serious complication during one lung ventilation.

Furthermore, recent studies have shown that one lung ventilation with a conventional tidal volume can involve lung injury associated with alveolar over distension and high airway pressure.

Therefore, lung protective ventilation with a low tidal volume during one lung ventilation has been suggested, and a recent study showed that protective ventilation during lung cancer surgery was associated with improved postoperative respiratory outcomes such as reduced incidence of acute lung injury and atelectasis.

During protective one lung ventilation limiting airway pressure and using low tidal volume, it is important to provide uniform alveolar expansion and maintain adequate oxygenation.

A previous study suggested that the decelerating inspiratory flow delivery used in pressure controlled ventilation improved ventilation/perfusion distribution and arterial oxygenation during one lung ventilation.

Moreover, according to a recent study during laparoscopic obesity surgery, pressure-controlled ventilation improved oxygenation compared with volume controlled ventilation, which was associated with higher instantaneous flow peaks and a better alveolar recruitment.

Unzueta MC et al (2007) total 58 patients with good preoperative pulmonary function scheduled for thoracic surgery were prospectively randomized into two groups. Those in group A underwent OLV initially with VCV for 30 min followed by PCV for a similar period of time. Those in group B underwent OLV initially with PCV for 30 min followed by VCV for a similar duration. Airway pressures and arterial blood gases were obtained during OLV at the end of each ventilatory mode. There were no differences during OLV in arterial oxygenation between VCV (Pao2, 206.1 +/- 62.4 mm Hg) and PCV (Pao2, 202.1 +/- 56.4 mm Hg; P = 0.534). Peak airway pressure was lower with PCV than with VCV (24.43 +/- 3.42 cm H2O vs. 34.16 +/- 5.21 cm H2O; P < 0.001). The use of PCV during OLV does not lead to improved oxygenation during OLV compared with VCV for patients with good preoperative pulmonary function, but PCV did lead to lower peak airway pressures. This study is needed for patients with severe obstructive or restrictive pulmonary disease.

Song et al. compared volume-controlled versus pressure-controlled ventilation-volume guaranteed mode (PCV-VG) during OLV. The result showed that in patients with normal lung function the airway pressure was lower in PCV-VG than that in VCV while the arterial oxygen tension remained the same.

OBJECTIVES:

•      AIM -To study the Pressure – controlled versus volume controlled ventilation during one-lung ventilation in decortication for empyema thoracis

•      Primary objective:

–     Airway compliance [PLATEAU AND PEAK PRESSURES]

–     Oxygenation in arterial blood gas analysis .

•      Secondary objective:

•      Intra operative bleeding

•      Postoperative complications

METHODS:

Study settings:

The study will be conducted in Department of Anesthesiology in collaboration with department of General Surgery King George’s Medical University, Lucknow after written informed consent will be obtained from either of the patients/Guardian

Study design:

·         Prospective, Randomised controlled parallel single blind Study

Study duration:

·         One year

Sample size:

·         Approximately 100 cases

Inclusion Criteria:

·         Patient posted for elective decortication surgery for empyema  thoracis requiring lung isolation surgery of ASA physiologic state II and III and aged between 20–50years.

Exclusion criteria

·         Patients with major organ dysfunction except lung disease, hemodynamic instability, or increased intracranial pressure

·         Age >50 years

·         Difficult airway.

·         History of chest wall deformity or thoracic surgery that could interfere with pulmonary resection.

·         Non pulmonary co-morbidities that could cause severe functional limitation(morbid obesity) or could limit survival(cancer).

·         Pulmonary hypertension at rest.

Methodology

•      100 patients undergoing decortication surgery for empyema thoracis are randomised into two groups.

•      Patients in V group will be receiving volume controlled ventilation during one lung ventilation while those in P group will be receiving pressure controlled ventilation.

•      A baseline ABG will be sent prior to shifting of the patient to the operation theatre.

•      After shifting the patient to the operation theatre and securing an  18G intravenous line, patient will be pre oxygenated for 3 minutes.

•      Patient will be given inj. Midazolam 1 mg iv and inj.glyco 0.02 mg iv as premedication.

•      A fixed method of anaesthesia will be used for induction i.e using inj fentanyl(1-2 ug/kg),inj propofol(2 mg/kg) and inj vecuronium(loading 0.1 mg/kg) during continuous supply of oxygen,air and sevoflurane.

•      After intubating with an appropriate size of DOUBLE LUMEN TUBE of left side and confirming its placement by auscultation and finally by fibreoptic bronchoscopy,etco2 will be attached and patient will be put on mechanical ventilation.

•      After changing the position and maintaining the final position,double lumen tube is again checked by auscultation.

•      During surgery, haemodynamic monitoring (SBP,DBP, MAP, HR,ETCO2) is  done  continuously and noted at 0,5,15,30 AND 45 minutes intra operatively.

•      The tidal volume will be set as 6ml/predicted body weight and positive end expiratory pressure will be set at the level of 5 cm of water in both groups.

•      Arterial blood gas analysis will be performed pre-operatively,intra-operatively after 1 hour of one lung ventilation and then finally after extubation.

•      Plateau and peak pressures are recorded at all these stages including the basic parameters of the body like BP,HR,etco2 and arterial oxygen saturation independently during volume controlled and pressure controlled ventilation.

•      Intra-operatively multimodal methods of analgesia will be used including inj.fentanyl,inj.PCM (1 gm) and intercostal block on the thoracotomy side

SAMPLE SIZE

•      Sample size is calculated on the basis of maximum variation in PaO₂ during the observation time in two study groups using the formula :

•      Where s₁ = 83.8 The maximum SD of PaO₂ during the observation time in first groups,

•      s₂ = 82.4   The maximum SD of PaO₂ during the observation time in second groups

•      (Ref. Zhu et. al.)

•      d = min(s₁, s₂) the minimum mean difference consider to be clinically significant

•      type I error α = 5% corresponding to 95% confidence level

•      type II error β = 10% for detecting results with 90% power of study

•      Loss to followup = 10%

•      So the required sample size

•      n = 30 for each group

STATISTICAL ANALYSIS

The statistical analysis and correlation will be done using SPSS (statistical package for social sciences) version 21.0 Statistical Analysis Software. The values will be quantified (%) and mean ±SD will be calculated.

Project Plan:  During one lung ventilation we will keep two groups of patients on volume controlled ventilation and pressure controlled ventilation respectively and we will compare oxygen saturation of the patient during both ventilations.

Itemized Budget:

REFERENCES

1. Lin et al. also compared three different ventilation modes (VCV, PCV and PCV-VG) during OLV in elderly patients. It showed that the airway pressure and PaO₂ were both improved in PCV and PCV-VG group compared to VCV.
2. Licker M, Fauconnet P, Villiger Y, et al. Acute lung injury and outcomes after thoracic surgery. Curr Opin Anaesthesiol 2009;22:61-7.
3. Cerfolio RJ, Pickens A, Bass C, et al. Fast-tracking pulmonary resections. J Thorac Cardiovasc Surg 2001;122:318-24.
4. McKenna RJ Jr, Mahtabifard A, Pickens A, et al. Fast-tracking after video-assisted thoracoscopic surgery lobectomy, segmentectomy, and pneumonectomy. Ann Thorac Surg 2007;84:1663-7; discussion 1667-8.
5. Yang M, Ahn HJ, Kim K, et al. Does a protective ventilation strategy reduce the risk of pulmonary complications after lung cancer surgery?: a randomized controlled trial. Chest 2011;139:530-7.
6. Schultz MJ, Haitsma JJ, Slutsky AS, et al. What tidal volumes should be used in patients without acute lung injury?  Anesthesiology  2007;106:1226-31.
7. Blum JM, Stentz MJ, Dechert R, et al. Preoperative and intraoperative predictors of postoperative acute respiratory distress syndrome in a general surgical population. Anesthesiology 2013;118:19-29.
8. Licker M, de Perrot M, Spiliopoulos  A, et al. Risk factors for acute lung injury after thoracic surgery for lung cancer. Anesth Analg  2003;97:1558-65

Informed consent

Title of project: VOLUME VERSUS PRESSURE CONTROLLED VENTILATION DURING ONE LUNG VENTILATION IN DECORTICATION FOR EMPYEMA THORACIS

Investigators: Dr Deepali Chandra, JR-1, Department of Anaesthesiology, KGMU, Lucknow.

Mob No. 07376510525; Email ID: deepali.8sep@gmail.com

Chief Supervisor: Prof. Dinesh Singh, Professor,  Department of Anaesthesiology, KGMU, Lucknow

Co-supervisors: Prof. GP Singh, Professor,  Department of Anaesthesiology, KGMU, Lucknow

Prof. BB Kushwaha, Professor,  Department of Anaesthesiology, KGMU, Lucknow

Dr. Ravi Prakash, Assistant Professor,  Department of Anaesthesiology, KGMU, Lucknow

Dr. Shefali Gautam, Associate Professor,  Department of Anaesthesiology, KGMU, Lucknow

Subject’s Full Name ________________________________________________

 Date of Birth/Age_________________________________________________

Address _________________________________________________________

Patient/Parent/Guardian Consent PART 1

Purpose of the study- To study the Pressure – controlled versus volume controlled ventilation during one-lung ventilation in decortication for empyema thoracis.

Study Procedure:  Prospective, Randomised controlled parallel single blind Study

Risk from the study-None

Benefits from the study- This study to effect of Airway compliance [Plateau and Peak Pressures], Oxygenation in arterial blood gas analysis, Intra operative bleeding, Postoperative complications.

Complications–None

Compensation-none

Confidentiality- all the information and clinical documents of subjects of the study will be kept strictly confidential and will be shown only to the investigator, supervisor and co- investigators of the study. The result of study will be used for clinical and academic purpose and the name of the subject would not be disclosed.

Rights of the participants- Participation in the study is voluntary. Refusal to participate will not influence the care of patient in this hospital in any way.

Alternatives to participation in the study-None

PART 2

Consent

1        I confirm that I have read and understood the information sheet dated ___________for the above study and have had the opportunity to ask questions.

OR

I have been explained the nature of the study by the Investigator and had the opportunity to ask questions

2        I understand that my participation in the study is voluntary and that I am free to withdraw at any time, without giving any reason and without my medical care or legal rights being affected.

3        I understand that the sponsor of the clinical trial/project, others working on the Sponsor’s behalf, the Ethics Committee and the regulatory authorities will not need my permission to look at my health records both in respect of the current study and any further research that may be conducted in relation to it, even if I withdraw from the trial. However, I understand that my Identity will not be revealed in any information released to third parties or published.

4        I agree not to restrict the use of any data or results that arise from this study provided such a use is only for scientific purpose(s)

5.  I agree to take part in the above study

Signature (or Thumb impression) of the Subject/Legally Acceptable Representative:___________________

Signatory’s Name:______________________________

Date:_____________________________

Relationship with subject:_______________________________

Investigator’s statement:-

I, the undersigned have explained to the parent/guardian in a language she/he understands the procedures to be followed in the study and risks and benefits.

Signature of the Investigator:                                                  Date:

Name of the Investigator:

Signature of the Witness:                                                                     Date:

Name of the Witness: