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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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