ADVANCING
YOUR PRACTICE
Understanding
pneumonectomy
By Penny
L. Andrews, RN, BSN, and Nader M. Habashi, MD, FACP,
FCCP
Various diseases or traumatic
injury may require the surgical removal of a single
lobe of the lung (lobectomy) or the entire lung (pneumonectomy).
The most common reason for a pneumonectomy is lung cancer.
Other reasons may include traumatic chest injury with
irreparable damage to the bronchus/major blood vessels
or severe forms of chronic obstructive pulmonary disease
(COPD) where lung tissue is severely damaged with impaired
gas exchange. Maintaining lung function during and after
a pneumonectomy is essential for adequate gas exchange.
This article will discuss the intraoperative concerns
and management of patients undergoing a pneumonectomy.
Background
In 1931, the first successful pneumonectomy was completed
in two stages by Rudolph Nissen on a young patient with
a thoracic crush injury.1 In 1933, the first
single-stage pneumonectomy was successfully completed
on a patient with lung cancer by Graham and Singer.
Currently, there are two
types of pneumonectomy: simple pneumonectomy, or the
removal of the affected lung, and extrapleural pneumonectomy
where not only the affected lung is removed, but also
part of the diaphragm, parietal pleura, and pericardium
linings may be removed and replaced by a synthetic patch.
An extrapleural pneumonectomy is an extensive surgery
primarily for the treatment of pleural malignant mesothelioma.
Malignant mesothelioma is a rare form of cancer affecting
mesothelial cells of the body's serous membranes. The
most common form of malignant mesothelioma affects the
pleura (lining of the lung cavity) but other forms can
also affect the lining of the abdomen (peritoneum) or
heart (pericardium).
Physiology
Although it’s possible to live with only one lung,
the remaining lung must assume the full workload for
gas exchange and perfusion where it was previously shared
between two lungs. After a pneumonectomy, survivors
generally become easily fatigued and have physical limitations
because the cardiopulmonary reserve is significantly
reduced and oxygen delivery may be limited as the heart
can become easily strained. Mild to moderate exercise,
or a hyperdynamic state (for example, sepsis) coupled
with the reduced capillary surface area postpneumonectomy,
diminishes the capacity of the pulmonary capillaries
to accommodate higher flow without raising pulmonary
arterial pressure.2
Increased blood flow through
the reduced pulmonary capillary bed and resultant increased
pulmonary pressure may lead to pulmonary edema. Pulmonary
edema is a serious concern in the postoperative phase
of a pneumonectomy patient and may impact mortality.
Although pulmonary edema may worsen lung function, it
also serves to reduce the pressure in the pulmonary
capillary bed by the transudation of fluid into the
interstitium of the lung, effectively reducing the circulatory
volume and offloading pressure generated on the right
heart.2 If the pressure and load on the right
heart isn’t relieved, the right heart ultimately
fails and is almost uniformly fatal. The mechanical
ventilator, mode, and settings chosen become important
because ensuing lung edema will ultimately decrease
lung compliance and cause an increase in lung collapse
(atelectasis).3
Atelectasis or loss of
lung volume has been shown to increase pulmonary vascular
resistance and worsen right heart load and systemic
perfusion, ultimately contributing to right heart failure.3
Pulmonary vascular resistance is elevated at extremes
of lung volume (low and high) and optimized at normal
functional residual capacity. Although counterintuitive,
an increase in airway pressure resulting in lung recruitment
(decreased atelectasis) can reduce right heart load
and dilatation, preventing right heart failure.3
The likelihood of developing pulmonary edema and right
heart failure is potentiated by preexisting pulmonary
hypertension or chronic lung disease and is a source
of morbidity postpneumonectomy. This phenomenon can
also occur in trauma and younger patients without comorbidities,
when the postoperative phase is complicated by hyperdynamic
states from multiple trauma, fever, and septic shock.
Preoperative preparation
Teaching patients and their families preoperatively
about the postoperative effects of pneumonectomy is
important, so that they know what to expect from surgery.
Teaching should include importance of pulmonary management,
ambulation, arm/shoulder exercises of operative side,
and pain control. Patients may be intubated for several
days, require opioid analgesics to control pain, have
chest tubes in place, and require physical assistance
until they gain strength. Early pulmonary hygiene and
physical therapy are imperative for extubation and mobilization.
Patient-controlled analgesia infusion pump may be used
to control pain via I.V. or thoracic epidural delivery.
Although it’s important to control pain and anxiety,
clinicians must remember that oversedation can lead
to atelectasis, worsening lung function, and secretion
retention, if an effective cough is diminished or eliminated.
Therefore, utilization of a pain-scoring system may
be helpful to reduce the potential for oversedation.4
Clinicians must also be
mindful of how to prepare patients for a pneumonectomy.
Traumatic injuries or emergent pneumonectomies may not
provide an adequate time frame for ideal lung recruitment
or volume management. If the patient isn’t intubated
prior to surgery, incentive spirometry, coughing, and
deep breathing exercises are encouraged. If intubated,
modes of mechanical ventilation that promote alveolar
recruitment should be considered; lung recruitment,
preoperatively, is crucial to reduce the risk of atelectasis.
As with any major surgery,
it’s ideal to have the patient euvolemic prior
to the surgery. This may be especially difficult in
the traumatically injured patient if they’re undergoing
fluid resuscitation while preparing for surgery.
Intraoperative
concerns
The patient undergoing a pneumonectomy requires a double
lumen endotracheal tube (DL-ETT) also known as an endobronchial
double-lumen tube, during the operative procedure. The
DL-ETT has two separate lumens (one bronchial and one
tracheal lumen) within a single tube. Depending on the
lung to be removed, a right or left DL-ETT will be placed.
If the left lung is to be removed, a right DL-ETT will
be placed in the right bronchus and vice-versa. The
DL-ETT allows the clinician to selectively oxygenate
and ventilate the unaffected lung during the operative
procedure.
After the affected lung
is removed and the operation is complete, the DL-ETT
should be changed to a single lumen ETT due to the increased
size and airway resistance and difficulty passing a
suction catheter to remove secretions. Airway resistance
through a DL-ETT is significantly increased as the intraluminal
diameter of each lumen is smaller, limiting effective
pulmonary hygiene.5 For example, a 39-French
DL-ETT (Sheridan catheter) used for an averaged sized
adult has a bronchial lumen of 6.9 mm and tracheal lumen
of 7.1 mm.6
A pneumonectomy requires
a thoracotomy to visualize and remove the lung intraoperatively.
The patient is placed in the lateral position with the
operative side facing upward. After the patient is appropriately
prepped and draped, a posterolateral thoracotomy incision
is started from the anterior chest around the curve
of the ribs posteriorly to a point below the shoulder
blade.
One or two ribs may need
to be removed to access and remove the affected lung.
The lung to be removed is deflated with cessation of
ventilation and absorption of the gases. The pulmonary
artery and vein are cleanly dissected and ligated, and
the main bronchus of the operative lung is clamped prior
to removal to ensure that fluid doesn’t enter
the airways. The lung and the hilar structures to be
removed are dissected, divided, and ligated. The end
of the bronchus (stump) is secured with staples or sutures
to prevent air from leaking through the stump. Additionally,
the bronchial stump may be reinforced with biological
material such as a pericardial or intercostal flap to
prevent leakage. The adjacent lymph nodes are removed,
and the phrenic nerve is severed on the affected side.
After the affected lung
is removed, the mechanical ventilator's settings and
parameters for the remaining lung require close monitoring.
Ventilator settings will require adjustment to maintain
adequate recruitment of the remaining lung without creating
overdistention. Chest tubes are placed between the pleural
space to facilitate drainage of air, serous fluid, and
blood from the surgical site, and the thoracotomy is
closed with staples.
Postoperative care
Fluids that leak from the parietal pleura and mediastinum
fill the space where the affected lung was removed.
The empty space (air) on the pneumonectomy side is gradually
reabsorbed and replaced by the fluid. Over time, the
hemithorax (chest wall) on the pneumonectomy side progressively
contracts by narrowing the intercostal spaces and crowding
the ribs. The affected hemi-diaphragm elevates to decrease
the thoracic volume and the amount of fluid needed to
obliterate the space vacated by the recently removed
lung. Tracheal and mediastinal shifting towards the
pneumonectomy side occurs because of the hemithoracic
volume loss and hyperinflation of the remaining lung
after a pneumonectomy. However, atelectasis of the remaining
lung on the nonsurgical side or a bronchopleural (BP)
fistula, hemorrhage, or empyema on the surgical side
will cause a mediastinal shift away from the surgical
side. Tracheal or mediastinal shift back to midline
or away from the surgical side should be considered
serious, warranting further investigation. Serial chest
X-rays are important to closely monitor mediastinal
shifting, in addition to atelectasis of the remaining
lung.
Mechanical ventilation
Respiratory failure is a leading cause of death postpneumonectomy,
and derecruitment or hyperinflation of the remaining
lung may prove deleterious. The clinician is challenged
to provide enough airway pressure so that the remaining
lung stays adequately recruited but isn’t overdistended,
while the surgical stump is protected from injury. Although
using a lower airway pressure is important to minimize
pressure on the bronchial stump, a nonjudicious reduction
in airway pressure may result in atelectasis that increases
injury to the airways and risk of BP fistula.7
If the remaining lung becomes atelectatic, the patient's
deteriorating condition may force clinicians to increase
airway pressure for gas exchange and recruitment, increasing
the risk of BP fistula or major breakdown of the bronchial
stump.7
Balancing the appropriate
airway pressure postpneumonectomy may be difficult.
In cases of severe atelectasis of the remaining lung,
a DL-ETT may be re-inserted and the patient placed on
independent lung ventilation. This technique allows
the clinician to regulate the ventilator settings independently
for each “lung.” In this case, the atelectatic
lung may be recruited, while the bronchial stump is
not exposed to airway pressure preventing further damage.
Modes that raise mean airway pressure for recruitment
such as high frequency oscillatory ventilation (HFOV)
or airway pressure release ventilation (APRV) may be
considered.8
Ventilator modes should
also be considered, allowing unassisted, unrestricted
spontaneous breathing early in the postoperative phase.
Unassisted spontaneous breaths improve lung recruitment
without increasing airway pressure, while simultaneously
decreasing right atrial pressure and increasing venous
return, cardiac output, and renal/gut perfusion.
Fluid loss may be compensated
with volume resuscitation using crystalloids, colloids,
and blood products. Fluid overload may be treated with
fluid restriction or diuretics. Systemic hypertension
postpneumonectomy can adversely affect peripheral oxygen
delivery, produce heart strain, and precipitate pulmonary
edema requiring prompt treatment. Afterload reducing
agents, such as nitroprusside or hydralazine, may be
used to treat systemic hypertension. However, negative
inotropic agents, such as diltiazem, should be avoided
in patients who exhibit signs of systemic hypoperfusion
(for example, lactic acidosis or worsening organ function).
Patients who exhibit systemic hypoperfusion or right
heart dysfunction may benefit from dobutamine, as it
can improve the energetics of the right ventricle.9
Additionally, dobutamine and other beta-agonists have
been shown to improve lung edema clearance, ultimately
improving lung compliance.10 In clinical
trials, levosimendan has demonstrated similar [inotropic]
effects as dobutamine, with the addition of producing
direct pulmonary vasodilatation.11 These
agents may help maintain systemic oxygen demands improving
cardiopulmonary function.11
Recovery
Patients are transferred to an ICU postoperatively where
vital signs, hemodynamic and cardiopulmonary status
are closely monitored. Additionally, patients should
be monitored for cardiac dysrhythmias. The surgeon should
be notified immediately of any changes that may indicate
bleeding, BP fistula, or infection. Signs of a BP fistula
postpneumonectomy include persistent chest tube leak,
inhaled tidal volume less than exhaled tidal volume,
or pneumonthorax.
Increased heart rate and
a drop in blood pressure may be signs of bleeding, and
increased temperature and white blood cell count may
indicate an infectious process. If the patient has a
chest tube postpneumonectomy, the chest tube drainage
and the thoracotomy site should be monitored for excessive
bleeding. Typically, the chest tube is placed to straight
drainage rather than wall suction. Patients may remain
on the ventilator for several days to weeks depending
on the overall status of the patient. Arterial blood
gases and chest X-rays are used to monitor oxygenation,
ventilation, and lung recruitment. If necessary, a bronchoscopy
may be performed to remove secretions or to visualize
the bronchial stump.
Physical therapy should
be implemented as soon as possible to return the patient
back to independent activities of daily living. Mechanical
ventilation is weaned as tolerated to extubation, and
chest tubes are closely monitored for air leaks and
drainage and removed when clinically indicated.
References
1. Nissen R. Classics in thoracic surgery: total pneumonectomy.
Ann Thorac Surg. 1980;29(4):390–394.
2. Kopec S, Irwin R, Umali-Torres C, et al. The postpneumonectomy
state. Chest. 1998;114:1158–1184.
3. Duggan M, McCaul C, McNamara P, et al. Atelectasis
causes vascular leak and lethal right ventricular failure
in uninjured rat lungs. Am J Respir Crit Care Med.
2003;167:1633–1640.
4. De Jong M, Burns S, Campbell M, et al. Development
of the American Association of Critical-care Nurses'
sedation assessment scale for critically ill patients.
Am J Crit Care. 2005;14(6):531–544.
5. Hannallah M, Miller S, Kurzer S, Tefft M. The effective
diameter and airflow resistance of the individual lumens
of left polyvinyl chloride double-lumen endobronchial
tubes. Anesth Analg. 1996;82:867–869.
6. Anantham1 D, Jagadesan R, Tiew P. Clinical review:
independent lung ventilation in critical care. Crit
Care. 2005;9:594–600.
7. Tsuchida S, Engelberts D, Peltekova V, et al. Atelectasis
causes alveolar injury in nonatelectatic lung regions.
Am J Respir Crit Care Med. 2006;174:279–289.
8. Brambrink A, Brachlow J, Weiler N, et al. Successful
treatment of a patient with ARDS after pneumonectomy
using high-frequency oscillatory ventilation. Intensive
Care Med. 1999;25:1173–1176.
9. Yi K, Downey F, Bian X, et al. Dobutamine enhances
both contractile function and energy reserves in hypoperfused
canine right ventricle. Am J Physiol Heart Circ Physiol.
2000;279:H2975–H2985.
10. Tibayan F, Chesnutt A, Folkesson H, et al. Dobutamine
increases alveolar liquid clearance in ventilated rats
by beta-2 receptor stimulation. Am J Respir Crit
Care Med. 1997;156:438–444.
11. Morelli A, Teboul JL, Maggiore SM, et al. Effects
of levosimendan on right ventricular afterload in patients
with acute respiratory distress syndrome: a pilot study.
Crit Care Med. 2006;34(9):2487–2493.
Source: OR Nurse.
March 2009.
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