Relief of Post-Operative Pain:
Post-thoracotomy Pain: Assessment and
Relief
Notes for a lecture to the Annual Respiratory
Symposium
3/14/92
F.W. Grannis jr.M.D.
Thoracotomy with resection of lung tissue is frequently required for ablation of bronchogenic
carcinoma and less often for various benign lung diseases. The patient with normal lung function tolerates
removal of one lung well in almost all cases. Unfortunately almost all lung cancer patients have
significant pulmonary functional deficits caused by the same cigarette smoking that caused the cancer.
These patients can have major problems after resection and it is often a difficult problem for the
pulmonologist and thoracic surgeon to decide whether the patient can survive the necessary surgery. Post-
resectional pulmonary function studies at 3-6 months post-op can be accurately predicted by the formula
FEV1=18-x\18 x FEV1 (pre-op)
where x=the number of segments in the lung tissue removed.
For example if the pre-op FEV1 is 3.0 and the left lung containing 8 bronchopulmonary segments is to be
removed then the calculation is
FEV1 (post-op)= 18-8/18 x 3.0
10/18 x 3
1.67 liters.
Patients with a predicted FEV1 of > 1.0 can generally function reasonably well. and patients can survive
with as little as 0.7 l.. The problem with the calculations are that they involve PFTs a number of months
after the operation. Little is known about PFTs in the early post-op period, but what data does exist
indicates that FEV1 and other measurements are strikingly lower than the predicted values.
The primary tasks of the physician and the nurse are to preserve life and to alleviate suffering.
Management of post-operative pain is important for both reasons.
Post-thoracotomy pain is rated as severe by most patients. Further, it is well established that post-
thoracotomy pain is a major factor in the morbidity and mortality of thoracic surgical proceedures. It is
readily observable that patients complaining of post-op pain restrict deep breathing and cough in an effort
to prevent the sharp discomfort experienced during these activities. Multiple studies have demonstrated a
decrease in vital capacity, functional residual capacity (FRC), closing capacity (CC) ,FEV1, peak
expiratory flow (PEF), retention of secretions, atalectasis, increase in aAO2 gradient, decrease in O2
saturation and CO2 retention.
Breathing at a FRC below CC results in closure of small airways with
resultant >aAO2 gradient and atelectasis . Lowered PEF reflects inability to cough effectively. Failure to
clear secretions causes atelectasis and nosocomial pneumonia. These problems can result in respiratory
failure in otherwise normal patients but are of increasing importance in the elderly, the chronically ill and
the emphysematous patient. Respiratory failure is the primary morbidity after thoracotomy and results in
high mortality and morbidity and astronomical medical costs . Many different modalities have been
utilized in an attempt to control post-op pain.
1. PRN narcotics-
given either IM or IV is the traditional method of pain relief after operation. It has been
demonstrated in numerous studies to be ineffective. Variability in patient perception and toleration of pain
are enormous.Problems with assessment of patient pain are ubiquitous. Minimum effective concentration
of narcotics also varies tremendously between individuals as also does the amount of administered
narcotic required to produce a minimum effective concentration. Inadequate doses of medication are
typically given at infrequent intervals , leaving the patient uncomfortable and subject to the cascade of
problems listed above. The reasons for this are practical. First, the patient has to have drug levels decrease
to the point where he is uncomfortable. Next, a nurse, often overworked or caring for a more urgent
medical problem elsewhere, is delayed for a significant period of time. Then there are further delays while
narcotics are obtained from a locked cabinet and administered. In the case of IM injection there is a
further delay in uptake. Added to these logistic problems there is a poor understanding of narcotic
analgesics by many nurses and even more physicians; an unreasoning fear of producing addiction and a
reluctance to give adequate doses . Finally there are a number of inherent side effects to the use of
narcotics ; nausea, vomiting, constipation, pruritus that make their use unpleasant for the patient. Other
side effects, CNS depression and respiratory depression, if excessive, can magnify the pulmonary
complications of the thoracotomy itself. Clearly a different approach is needed.
2. PCA (patient controlled analgesia)-
employs a microcomputer mechanism to allow pre-specified amounts of narcotic to be available to the
patient immediately upon demand. This technique has been shown in numerous good studies to provide a
more constant blood level of narcotic and better pain control with smaller total dosage of medication. It
also frees up nurses for more critical tasks.
In my experience PCA works reasonably well but there are often problems with patient
compliance. The idea behind PCA is quite simple. Each time the patient feels pain he is to push a button.
Despite this simplicity, it is frustrating that many patients will try to "outsmart" the system. "I didn't want
to push the button because I might become an addict." On other occasions nurses will intervene and push
the button for the patient. Obviously the confused, demented or obtunded patient is a problem. For these
reasons PCA often does not result in optimal pain relief.
3. Continuous drip narcotics-
can be given IV, but an important safety feature of PRN or PCA narcotic use is lost, i.e. if the patient is
obtunded by excessive levels of narcotics then he will not ask for or receive another dose. PCA systems
allow the use of continuous drip narcotics with supplementary doses, but constant drip levels need to be
kept low to enhance safety. If continuous drip narcotics are used, a coded system that does not allow
patient or family tampering is imperative. Continuous drip narcotics are ideal in the pain control of the
terminal , suffering patient where a death secondary to respiratory depression in not to be feared.
A technique of nurse-controlled intravenous narcotics has been reported to give good results in
post-operative pain. In a different medico-legal climate this would be an interesting technique to try here.
4.Paravertebral (intercostal nerve) block-
Percutaneous intercostal nerve blocks with local anesthetics have been studied many times in the past and
found effective in controlling post-thoracotomy pain and improving pulmonary function. The major
disadvantage to the technique is that multiple intercostal nerves above and below the incision (or injury)
must be blocked. This means multiple unpleasant injections for the patient and multiple opportunities for
complications such as pneumothorax, hematoma and inadvertent subdural injection of local anesthetic to
occur. Since duration of local anesthesia is only a few hours with lidocaine and no more than 8 to 12
hours with bupivicaine and 1:200,000 epinephrine repeated injections are necessary. "Rube Goldberg"
devices with multiple indwelling intercostal catheters have been used. The techniques are seldom used
because they are labor intensive, uncomfortable for the patient and often ineffective.
5 Epidural anesthesia-
catheters are placed by the anesthesiologist either before or after thoracotomy. The technique is difficult
and proper placement in the epidural space can be problematic. Improper technique can result in failure of
analgesia, epidural hematoma, spinal anesthesia. Contamination can cause meningitis or epidural abcess.
The catheter can be infused either intermittently or by constant infusion , with narcotics, local anesthetics
or a combination of both into the epidural space. Local anesthetics have the disadvantage that they block
sympathetic outflow from the cord and can cause problems with hypotension. Narcotics locally penetrate
the dura and bind with endorphin receptors in the spinal cord, blocking transmission of pain impulses to
higher centers. This technique can give excellent, even complete, relief of pain , but it sometimes is
unsatisfactory. Some patients are afraid of spinal injections and refuse the technique. In others with spinal
surgery, coagulation defects or sepsis, the technique is contraindicated. Intermittent doses are often
delayed because the anesthesiologist doesn't want to come in the middle of the night. The continuous
technique works better, but in some local hospitals, anesthesiologists and nursing administrators are
unwilling to use the technique because of potential medicolegal risks. Supplemental systemic narcotics
must be used judiciously because of the risks of respiratory depression. This is a special problem when
catheters become displaced and epidural anesthesia fails. The patient then gets little or no pain relief.
Pruritus can become a major problem. Bladder dysfunction is common. Systemic uptake of narcotics is
present and significant respiratory depression can occur. Despite these potential problems, continuous
epidural narcotic infusion is probably the best technique commonly used today.
6. Cryoanesthesia-
is performed by dissecting the intercostal nerves and freezing them with a liquid nitrogen probe at -60 C
at the end of the operation. This effectively destroys the nerves but leaves a frameword for regrowth of
axons. It has been reported to provide good pain relief but can cause troublesome neuritis during the late
post-operative phase.
7. TENs-
uses electrical impulses to "distract" neurons from their usual recognition and transmission of pain
impulses. Pain perception is carried by the small C fibers of peripheral nerves. High frequency impulses
delivered by commercially available TENS transmittors stimulate activation of the larger A fibers. The
gate theory postulates that this causes inhibition of neurons in the substantia gelatinosa of the spinal cord
which inhibit the transmission of pain recognition carried by the smaller C fibers to higher centers in the
brain. Although studies have shown a therapeutic effect in postoperative patients, in my experience it is
seldom of significant value.
8. NSAIDs-
non-steroidal anti-inflammatory drugs were little used in the past because they were not available in a
parenteral form. Now ketorolac (Toredol) represents a powerful addition to the analgesic formulary.
NSAIDs inhibit production of prostaglandin synthesis by inhibiting the enzyme cyclo-oxygenase that
converts arachidonic acid into the prostaglandin cycle.
NSAIDs also inhibit thromboxane A2 synthesis and therefore platelet aggregation and can cause bleeding
complications.
NSAIDs cause a significant increase in ulceration of the stomach and duodenum, especially in older
patients. Ketorolac is a powerful analgesic when an initial dose of 60 mg. is followed by 30 mg. q 6 hours
in adults.
9 Continuous paravertebral block-
is a new technique based on intercostal nerve block. At the completion of thoracotomy the posterior
parietal pleura is stripped up off the chest wall over a five rib area centered over the intercostal incision.
The pocket created extends into the paravertebral area where the intercostal nerves leave the spinal
foramina. A plastic catheter is inserted through an intercostal space by needle puncture and positioned in
the pocket. A continuous drip of 1% lidocaine at a dose of 1cc./ 10
Continuous Paravertebral Block with Continuous
Lidocaine after Thoracotomy: A Descriptive Pilot Study.
by Elizabeth Sullivan, RN, MN, APN, Frederic W. Grannis
Jr., MD, FCCP, Betty Ferrell, RN, PhD and Mordecai
Dunst, MD.
From the Departments of Thoracic Oncology, Pulmonary
Medicine and Nursing Research, City of Hope National
Medical Center, Duarte CA
Please address requests for reprints to F.W. Grannis Jr.
MD, C/O Department of General and Oncologic Surgery,
City of Hope National Medical Center, 1500 Duarte Road,
Duarte CA
Abstract
Continuous paravertebral block (PVB) with bupivicaine has been reported
to be an effective analgesic technique in patients after thoracotomy1. We report a
retrospective study of PVB using a continuous drip of 1% lidocaine at a dose of 1
mg./kg/hour. A posterior parietal pleural pocket was created and cannulated with a
sixteen gauge polyethylene catheter. Lidocaine was perfused over a three day
period following surgery. Patients also had access to morphine sulfate (MS) via
patient controlled analgesia (PCA). Eighteen consecutive thoracotomies (in
seventeen patients) performed over a six month period were reviewed.
Serum lidocaine exceeded the toxic level of 5mg/ml in only one patient,
who experienced no clinical toxicity. Pain was evaluated by verbal analog scores
(zero = no pain and ten = worst pain), which averaged 3.02, 3.14 and 2.8 in the
three days following surgery, mean total daily MS doses were 24.3, 37.75 and
34.32 mg. (range 0-94 mg.). Sedation was scored on a 1 to 5 scale. Mean scores
were 2.78, 2.56 and 2.6. No patient died or had a major respiratory complication.
Continuous PVB with lidocaine appears to be a promising adjuvant
technique in the management of post-thoracotomy pain. Effectiveness needs to be
confirmed in a prospective randomized study.
Introduction:
Pain following surgery is a major cause of morbidity and mortality and
improved pain management results in improvement in post-surgical morbidity and
mortality. 2 Transection of skin, muscle and pleura, retraction of muscles,
ligaments, and intercostal nerves, pleural irritation by chest tubes and fractured
ribs all contribute to severe pain following thoracotomy. If pain is not adequately
controlled, a series of events, including shallow respiration, chest wall splinting
and avoidance of cough and deep breathing, result in atalectasis, ventilation-
perfusion mismatch, hypoxemia and pneumonitis. The end result can be prolonged
ICU and hospital stay, or even respiratory failure and death. Traditional treatment
with parenteral PRN opioids provides inadequate pain relief and superimposes
morbidity secondary to the sedative and respiratory depressant side effects of these
drugs. Because of these problems, in recent years, many surgeons and
anesthesiologists have been studying new techniques of pain control in the post-
thoracotomy patient. Local anesthetic intercostal nerve blocks have been tried by
many groups in the past, and have had some demonstrated benefit, but the
problems of multiple daily injections of multiple intercostal nerves, and the
impracticality of indwelling catheter systems to deliver local anesthetics
intermittently to multiple nerves, have resulted in abandonment of these techniques
by most groups.
Sabanathan et al, in 1988 , described a simple technique of continuous
regional anesthesia via a percutaneous catheter through which continuous
bupivicaine could be infused into a retropleural pocket, created by the surgeon at
the time of surgery, by dissecting the posterior parietal pleura off the chest wall,
over a five rib area, centered on the thoracotomy incision. They reported good
analgesia.
We report a pilot study, using a retrospective audit, of the effectiveness of
this technique. We have, however, substituted a continuous infusion of 1%
lidocaine at a dose of 0.1 cc/kg./hour (1mg./kg./hr.) for the bupivicaine used by
previous investigators.
Study Design:
A retrospective, descriptive study was designed to evaluate the
effectiveness of post thoracotomy, continuous infusion lidocaine, paravertebral
block (PVB) in controlling post operative pain. All consecutive patients who
underwent thoracotomy during a six month period from October 1, 1992 to April
30, 1993 were evaluated. In some thoracotomies performed during this period, the
pocket could not be made because of dense adhesions, pleural plaques or surgical
resection of the pleura. In seventeen patients (eighteen thoractomies) the pocket
was dissected. A 16 gauge, 12 inch long polyurethane, single lumen central venous
catheter with side holes * was introduced percutaneously through a low posterior
interspace and sutured in place. Earlier experience had shown that intermittent
dosing and smaller diameter catheters, are unsatisfactory because of frequent
catheter occlusion. Most patients had 10 cc of 1% lidocaine instilled in the pocket
intraoperatively, and all had a continuous infusion at a rate of 0.1 cc (1
mg.)/kg./hr). for three or four days after surgery. Intravenous PRN morphine
sulfate (MS) was given until the patient was sufficiently awake to begin patient
controlled analgesia (PCA) with MS.
Results:
Demographics and Surgical Variables:
* Arrow International Inc. Hill and George Avenues, Reading PA 19610; model
number AK-04400)
There were 18 thoracotomies on 12 males and 5 females (one male patient
had bilateral thoracotomy) with a mean age of 58 years (range 22-82 years). 67%
of patients were operated for treatment of bronchogenic carcinoma, 22% for other
neoplasms and 11% for benign disease.
Operations included pneumonectomy 11%, lobectomy 33%, and
wedge or segmental resection 55%. (Table 1). Rib fracture, usually "green stick"
was noted in 28% of patients secondary to retraction. Ribs were reapproximated
by figure of eight doubled #1 Vicryl sutures placed through drill holes in the lower
rib in 83%. This technique is employed to avoid pain consequent to compression
of intercostal nerves. Rib resection was performed in one patient (6%) and pleural
adhesions were dissected in 41%.
Mean forced vital capacity was 3.48 liters (range 1.6-5.5 l;
predicted mean 4.07 liters); mean FEV1 was 2.66 liters (range 0.92-4.58 ;predicted
mean 3.21 l). (Table 2)
Pain Outcomes:
Post op day (POD) #1 was defined as starting at the completion of surgery
and ended at 7 AM the following morning. Each subsequent POD consisted of
three nursing shifts of eight hours each, from 7AM to 7AM.
Serum lidocaine levels were obtained on POD#2 and 3 in 14 and 13
patients respectively. Mean levels were 2.39 mg on POD# 2 (range 1.2 to 5.9) and
3.7 mg on POD#3 (range 1.8 to 5.0). (Table 3).. One patient had a serum level over
5mg/ml. at 5.9mg/ml.. No patient experienced clinical toxicity secondary to
lidocaine . (Table 3).
The total dose of MS given over each eight hour shift and twenty four hour
day were recorded. Mean total doses of M.S. were 24.3 mg (range 0-88 mg.),
37.75 mg. (range 9-94 mg.) and 34.32 mg. (range 0-108 mg.) on POD #1-3. (Table
4).
Adequacy of analgesia was documented by multiple assessments by nurses
during each shift by verbal analog, zero to ten pain rating scale . Since the study
was retrospective, differential scores at rest and during cough and activity were not
obtained. Mean pain rating scores were 3.02 (range 0.5-8.0) , 3.14 (range 0.4-
4.8)and 2.8 (range 0.2-4.3) on POD#1-3 respectively.
The combination of continuous PVB and PCA MS provided adequate pain
relief in most patients. In one patient a continuous morphine basal rate was
required for pain control for one day for treatment of unstable angina pectoris.
Four patients were given additional PRN MS doses and one patient received a
single dose of ketorolac.
Nurses noted patient state of sedation multiple times each shift on a one to
five sedation scale . Mean sedation scores ( 1=alert; 5=comatose) were 2.78
(range 1-4), 2.56 (range 1.3-3.6) and 2.6 (range 1-3.6) on POD#1-3. No patient
became markedly obtunded or comatose.
Complications:
One catheter occluded on post-operative day 3. There were no other
complications referable to the catheter.
Fourteen patients were extubated in the recovery room; one patient was
extubated in the ICU later on the first PO day and two patients were extubated the
following morning. Arterial blood gas samples were obtained daily. Results in
patients following extubation are tabulated in Table 5. Episodes of desaturation
below 88% were recorded in two, one and three patients on POD#1-3 respectively.
Atalectasis was noted on exam or roentgenogram in three, two and two
patients on POD#1-3. No patient required bronchoscopy or reintubation. There
were no cases of pneumonia, respiratory failure or death. One patient, who had
undergone previous coronary bypass grafting and multiple coronary angioplasties,
developed unstable angina pectoris on POD#3 and required angioplasty.
Discharge from ICU was after a mean of 3.29 days (range 0-7). No patient
was readmitted to the ICU. Time of hospital discharge was after a mean of 8 days
(range 5-12). (Table 6).
Discussion:
Many investigators have attempted to take advantage of the theoretical
advantages of regional anesthesia in the management of post-thoracotomy pain.
Percutaneous intercostal nerve blocks have been demonstrated to be
effective in reducing pain, reducing dosage of opioids and improving pulmonary
function tests in well designed, randomized, double blind, prospective studies of
intercostal nerve block given during surgery , and post-operatively Although
the technique has proven efficacy, logistic considerations and the patient
discomfort and risks associated with repeated blocks, result in infrequent
utilization of this technique in post-operative patients.
A variety of systems of single and multiple indwelling intercostal
catheters have been described to allow serial or continuous regional analgesia.
These techniques have not been adopted by thoracic surgeons for general usage.
The difficulty in explaining how a single intercostal injection or catheter can
provide wide field analgesia has been explained by studies demonstrating passage
of the injected local anesthetic agent retrograde along the subcostal space into the
paravertebral space. While the paravertebral space can be cannulated
percutaneously, there is a high failure rate with this technique.
In an effort to avoid some of the methodological difficulties inherent in
intercostal nerve block, investigators have tried placement of indwelling
intrapleural catheters with intermittent or continuous instillation of local anesthetic
agents for post operative pain control. It is assumed that the anesthetic will
diffuse across the pleura to bathe the intercostal nerves, thus providing an
equivalent to intercostal nerve blocks, without the need for multiple injections.
Three single arm studies have found this technique to be valuable after
thoracotomy in children. and three double-blind, randomized studies have
shown improved pain control, reduced narcotic dose and improvement of various
respiratory parameters. Four other studies have found the technique to be
ineffective, and in two further studies, intrapleural analgesia was found to
be inferior to intercostal block.6, High measured levels of anesthetic in chest tube
effluent help to explain the variable results . It is important to position the patient
supine or operated side down in order to keep the agent in contact with the
posterior parietal pleura. 13
In 1988, Sabanathan described a technique that combines the advantages of
intercostal block with those of intrapleural analgesia. At the completion of
thoracotomy, the pleura is stripped off the posterior chest wall over a five rib area,
centered on the incision. A percutaneous plastic catheter is placed in the pocket
thus created, and local anesthetic is infused during closure and for a number of
days after surgery into the paravertebral space.1 Three subsequent randomized
double blind studies, two by the same group and one from other investigators
have shown the technique to be effective, while a fourth study found no
advantage over saline infusion.
All of these studies have utilized bupivicaine, presumably because it's long
duration of action carried an advantage when intermittent injections were used.
Toxic plasma levels of bupivicaine are generally considered to lie between 2 and 4
mg/ml. Numerous studies have used 1:200,000 epinephrine in conjunction with the
bupivicaine. Other groups have avoided it because of perceived problems with
hypertension and tachycardia . There is no improvement in analgesia with the use
of 0.25% vs. 0.5% bupivicaine. Initial doses of 100 mg. (20 cc of 0.5%)
bupivicaine and total doses of 400 mg/24 hours have generally not resulted in
serum levels above 2 mg/ml, but higher levels can occur especially in children. 13
In one remarkable case 20 cc of 0.375% bupivicaine was given intrapleural q6
hours for 130 days in a cancer patient. Plasma levels remained between 1-2mg/ml.
at all times.
We were concerned about the incidence of high blood levels of bupivicaine
in the series cited above and the relative dearth of information regarding the
pharmacokinetics and toxicity of bupivicaine. Since regional anesthetic was to be
delivered continuously, there seemed to be little advantage to using a long acting
drug. Accordingly, we elected to utilize lidocaine. Lidocaine, at the dosage used in
this study (1 mg/kg/hour), is routinely given safely, intravenously in critically ill
intensive care unit patients. 300-400 mg/hour of lidocaine have been given
intrapleural with minor toxicity and serum levels at or below 4.7mg/ml. 28 Our
patients experienced no detectable adverse response to the drug, and measured
levels of serum lidocaine remained below the toxic range (>5 mg/ml.) in all but one
patient.
At our institution, verbal pain rating scores are routinely obtained by nurses
in post-operative patients. Optimally, pain scores would have been obtained at rest
and with cough and movement, but since this was a retrospective study, these
values could not be obtained. Nevertheless, the mean pain scores demonstrated
quite good pain control. Nurses and physicians were subjectively impressed by the
apparent level of analgesia provided. Although the PVB provides analgesia, it is
usually not sufficient in itself to provide adequate pain relief, and adjuvant
medications are required.
Mean total MS doses/day were also low. This was true in spite of the fact
that the patient who had bilateral thoracotomies, had by far the highest MS
requirements. Low opioid doses resulted in low sedation scores and an absence of
serious morbidity and mortality.
It is not known how this technique compares with epidural methods. One
disadvantage is the technical difficulty of creating the paravertebral pocket in some
patients with pleural disease. On the positive side, an anesthesiologist with special
skills is not required; it is inexpensive; catheter related malfunction is rare; pruritus
was not seen.
In summary, we have confirmed Sabanathan's favorable experience with the
technique of continuous PVB following thoracotomy. We found continuous PVB
with 1% lidocaine to be a simple, safe and effective technique in the care of our
patients. Relative effectiveness of PVB needs to be tested in prospective,
randomized studies comparinkg./hour is started during closure of the
chest and continued until the chest tubes are discontinued. The originators of the technique note that it
provides excellent analgesia and caused no complications in their experience. I have used the technique in
five patients and was impressed by the analgesia produced , without the obtundation and respiratory
depression associated with narcotic techniques.
I propose to carry out a larger trial of continuous paravertebral block on the thoracic surgical
service at City of Hope. We will place the catheter in surgery and infuse as above. Although chances of
complications appear to be small, it will be important during the early stages of the study to carefully
monitor the patient for the development of loss of sensation and motor power in the legs during the
infusion. The infusion system will have to be a closed one so that no inappropriate medications are given.
The catheter will have to be clearly differentiated from an epidural catheter. Narcotic infusion in the
paravertebral area would cause no problems, but infusion of local anesthetic into an epidural catheter
could prove lethal.
The technique does nothing to control the central mechanism of pain perception and would not
be effective for pleural pain outside of the incision area, e.g., irritation of the diaphragm by the chest tube
rubbing on it. It is necessary therefore to provide a supplementary analgesic. We will use ketorolac given
I.M. while the paravertebral block is in place. If these techniques provide insufficient pain relief, narcotics
provide a fallback position.
The expertise of the Nursing Department at City of Hope in the understanding and management
of pain should provide an opportunity to quantitate in scientific fashion the value of this technique that
would not be available in most area hospitals. I value your participation in this study and welcome your
feedback. Please do not be shy about suggesting changes and improvements in the protocol.