Cerebral Oxygenation After Lung Resection
Condition: Elective; Lung Resection; Surgery
Study type: Interventional
Phase: Phase 1

Summary: 
      The investigators hypothesize that the lung resection would be associated with lower jugular
      bulb oxygen saturation in patients with severe pulmonary dysfunction than in patients with
      healthy lung functions.
    

Detailed description: 
      Surgery remains the treatment of choice for patients with resectable lung cancer. However, a
      significant proportion of patients undergoing lung resections have the associated condition
      COPD,1 which increases the risk of perioperative complications and death. New techniques in
      anesthesiology and critical care have enabled patients with COPD to have better outcomes
      following lung resections. Nowadays, patients with limited lung function, who would have been
      denied surgery according to the criteria proposed in the past, may undergo pulmonary
      resection with a low mortality rate.2

      Lung resection results in loss of lung parenchyma including residual healthy lung tissue and
      in reduction in the pulmonary vascular bed. A decrease in residual pulmonary vascular bed
      after lung resection causes an increase in the right heart afterload, and in others, it would
      be associated with an increase in the right heart preload.3

      The removal of lung parenchyma from patients with carcinoma of the lung, may lead to
      cardiopulmonary failure or death. A predicted postoperative forced expiratory volume in one
      second (FEV1) less than 0.8 to 1.0 liter is considered an indicative of a high risk of
      postoperative chronic ventilatory insufficiency. After pneumonectomy, FEV1 decreases by
      29-35% and forced vital capacity (FVC) decreases by 27-44%. After lobectomy, FEV1 and FVC
      decrease to12-23% and 10-30%, respectively.4

      After lobectomy in patients with normal pulmonary functions, there is a transient good
      maintenance of gas exchange for only 6-12hours, then it is followed with progressive
      deterioration in oxygen delivery and intra-pulmonary shunt fraction because of peripheral
      atelectasis 4-13 days after surgery.5 Other investigators reported a significant decrease in
      maximal oxygen uptake (VO2-Max) and maximal work rate (WR-Max) by 27% and 42%, respectively,
      3 months after pneumonectomy, and by13% and 2%, respectively after lobectomy.

      In patients with moderate-to-severe pulmonary dysfunction there is significant worsening of
      pulmonary gas exchange; especially during one-lung ventilation (OLV) which is the mandatory
      technique to facilitate thoracic surgery. This worsening is more marked in patients
      undergoing right thoracotomies after lung resection.6

      Postoperative lung function changes in the elderly followed the similar trend as in patients
      with pulmonary dysfunction. The mean postoperative decrease in FEV 1 was 14.16% in the
      elderly, compared with a 29.23% decrease in patients with normal lung function ( P < 0.05).
      However, the operative morbidity in the elderly group was significantly lower than in
      patients with pulmonary dysfunction (23.3% vs. 60%).7

      The potential for postoperative neurocognitive dysfunction and its impact on the
      postoperative course has gained recent attention over the past few years.8 There is an
      interesting study for the changes in brain tissue oxygenation (rSO2) during OLV for thoracic
      surgery using near infrared spectroscopy (NIRS), otherwise known as cerebral oximetry, is a
      non-invasive device that uses infrared light to estimate brain tissue oxygenation which may
      occur during OLV. The investigators reported significant changes in rSO2 occur during OLV for
      thoracic surgical procedures without changes in hemodynamic or ventilatory parameters. They
      recommended future studies to determine the impact of such changes on the postoperative
      course of these patients.9

      According to the above evidences, the changes in oxygen delivery, oxygen uptake and
      intrapulmonary shunt after lung resection will be reflected on the cerebral blood flow and
      oxygen delivery and jugular bulb oxygen saturation in patients with impaired pulmonary
      functions rather than those with healthy lung functions.

      Oxygenation of cerebral venous outflow has been investigated as a neuro-monitor for more than
      50 years.10-12 Currently, jugular venous oxygen saturation (SjVO2) provides an indirect
      assessment of cerebral oxygen use and is used to guide physiologic management decisions in a
      variety of clinical paradigms.13-14 This is simply can be achieved through introducing of an
      intravascular catheter, similar to those used for central venous pressure monitoring, may be
      placed retrograde, via the internal jugular vein, into the jugular bulb at the base of
      skull.15

      Jugular venous oxygen is an indirect assessment of cerebral oxygen use. Simplistically, when
      demand exceeds supply, the brain extracts greater oxygen, resulting in decreased jugular bulb
      oxygen saturation. If cerebral blood flow (CBF) decreases, a point is eventually reached at
      which the brain can no longer completely compensate for decreased CBF by a further increase
      in oxygen extraction. At this point, oxygen consumption decreases and anaerobic metabolism
      with lactate production ensues. When cerebral oxygen supply exceeds demand, oxygen saturation
      of jugular bulb blood is increased.15

      To our knowledge there is no any study was done on the changes in cerebral oxygenation after
      lung resections, especially in the high-risk group with pulmonary dysfunction.

      Project Objectives:

      We hypothesize that the lung resection would be associated with lower jugular bulb oxygen
      saturation in the patients with severe pulmonary dysfunction than in the patients with
      healthy lung functions.
    

Intervention name(s): Monitoring of cerebral oxygenation
Intervention type(s): Procedure
Intervention description(s): The internal jugular vein will be cannulated using ultrasound guidance in a cephalad direction, using the Seldinger J-shaped guidewire and it will be advanced only for 2-3 cm beyond the needle insertion site to avoid vascular injury to the jugular bulb. At which point the catheter is advanced until resistance is met at the jugular bulb, usually about 15 cm. The catheter is then pulled back 0.5-1.0 cm so that the catheter does not continue to abut the roof of the jugular bulb and to minimize the cephalad vascular impact with head movement, thereby reducing the risk of vascular injury. Skull x-ray will be used to confirm placement.
Allocation: Non-Randomized
Intervention model: Parallel Assignment
Masking: Single (Outcomes Assessor)
Primary purpose: Screening
Keywords: Cerebral oxygenation; thoracotomy; lung resection; pulmonary dysfunction