30. Pulmonary Considerations

30. Pulmonary Considerations

Desmond H. Birkett, M.D.

The term minimal access has led to the misconception that a laparoscopic operation is a small or minor procedure and as a result is not associated with pulmonary complications. Proponents believe that minimally invasive proce- dures are associated with fewer postoperative pulmonary complications when compared to results after open operations; however, this has not been definitively proven, thus far. Both open and laparoscopic operations are associated with size- able decreases in the tidal volume and forced expiratory volume (FEV)-1. It has been demonstrated that, following laparoscopic-assisted colon resection, patients recover their pulmonary function more rapidly than after the same open proce- dure. This faster recovery may or may not be associated with a lower incidence of actual complications. When considering the possibility of pulmonary com- plications, after either open or closed procedures, attention must be paid to the magnitude of the operation, the length of the operation, and the expected post- operative course of the patient.

Before undertaking a laparoscopic procedure, as is the case for open oper- ations, the patient’s baseline pulmonary function must be considered and assessed. Similarly, postoperative patient management must take the lungs into account and should include measures that will improve postoperative pulmonary function and minimize the chances that a pulmonary complication will develop.

Last, all involved in the care of the patient should be “on the lookout” for signs and symptoms of pulmonary complications.

A. Preoperative and Intraoperative Considerations

I. Preoperative evaluation. A careful pulmonary history should be taken from every patient undergoing any operation, be it open or laparoscopic. Attention must be given to breathlessness, exercise tol- erance, and a smoking history. Enquiries must be made into a history of any prior pulmonary complications that may have occurred with any previous operation. For those patients whose history suggests they may have significant pulmonary compromise, a preoperative assessment with pulmonary function tests may be necessary. Such tests will objec- tively assess a patient’s lung function and will establish their baseline level of function. A formal consultation and evaluation by a pulmonary specialist is advised for patients with severe pulmonary disease and for some patients with moderate disease.

A pulmonologist, where appropriate, will institute a medication

regimen that will maximize the patient’s function. Furthermore, the

pulmonary M.D. will outline a treatment plan for the early postoper- ative period and can follow the patient after surgery. Rarely, a patient’s pulmonary function may be so poor as to preclude the use of laparo- scopic methods. Of note on this account, the first decade of advanced laparoscopic procedures has taught us that it is possible to complete laparoscopic procedures in some patients with moderate or even severe pulmonary disease by reducing the maximum insufflation pressures, minimizing the use of Trendelenburg position, and by taking short breaks during which the abdomen is fully desufflated. It has also been made clear that there is a small group of severely diseased patients who will not tolerate even a low-pressure pneumoperitoneum; early conversion in these cases is necessary and appropriate.

II. Preoperative dietary instructions. Probably the most devastating procedure-related pulmonary complication is aspiration at the time of intubation. Although this is primarily an anesthesiology problem, the surgeon can play an important part in its prevention by providing clear and explicit preoperative instructions. The patient groups that are at risk for this problem are those with gastric emptying problems and patients with esophageal abnormalities such as gastroesophageal reflux, achalasia, and esophageal obstruction due to tumor. All patients must be told to stop eating and drinking from midnight on the day of the operation. Patients who have achalasia of the cardia and those with known gastric emptying problems, such as diabetic gastroparesis, should be placed on liquids for at least 48 hours before the operation in an attempt to empty the esophagus and stomach of residual solid food.

III. Explanation of operation and anticipated postoperative course.

The need for postoperative pain medications can be reduced if the patient has a clear understanding of the procedure to be carried out, the anticipated postoperative course, and the amount and duration of pain they are likely to experience. Therefore, it behooves the surgeon to spend time with a patient preoperatively going over the planned pro- cedure and these points. The fact that incision-related pain will make deep breathing difficult and that pulmonary complications can develop after surgery should be explained to the patient. The importance of taking adequate pain medication and of using the incentive spirome- ter, of coughing, and of taking deep breaths postoperatively needs to be stressed. The fact that the patient can lower their chances of devel- oping a pulmonary problem by doing these exercises should be made clear.

IV. Intraoperative pain management measures. A patient’s postopera- tive pulmonary management may be significantly improved by the fol- lowing intraoperative manipulations.

1. Intraoperative infiltration of the port sites with a mixture of short- and long-acting local anesthetics before making the incision and placing the port. Proponents believe that this practice reduces postoperative pain.

2. The intravenous administration of the NSAID (nonsteroidal anti-

inflammatory drug) Toradol (15–30 mg) at the end of the opera-

tion can reduce early postoperative pain. It may not be advisable to use Toradol in patients in whom bleeding has been a problem during the laparoscopic operation because of the antiplatelet side effects of this group of drugs. Of note, the bleeding side effects have not been reported with 15 mg Toradol given intravenously.

This drug should be avoided in patients with a history of peptic ulcer disease or gastritis.

V. Prevention of postoperative vomiting. Vomiting and retching is a major postoperative complication that prolongs the patient’s recovery, enhances the postoperative pain, and may result in respiratory com- plications as a result of aspiration. This complication can be minimized or prevented via the intravenous injection of antiemetics at the end of the operation.

B. Postoperative Management

Careful consideration must be given to the ventilation and oxygenation of a postoperative patient who has just undergone a minimal access procedure. The following must be considered.

I. Patient monitoring

1. Ventilation: To ensure adequate ventilation in the recovery room, the respiratory rate and the adequacy of ventilatory excursion must be carefully monitored. The ventilatory demands are greater for laparoscopic patients as they recover from the CO

pneu- moperitoneum when compared to open patients due to the post- operative resorption of residual CO

in the abdomen and soft tissues (subcutaneous emphysema), which increases the PaCO

. This excess CO

must be “blown off ” by increasing the minute ventilation. Signs of inadequate ventilation include restlessness, agitation, and confusion. Pain will also limit ventilation; there- fore, an adequate pain management strategy must be in place for these patients immediately after surgery. An arterial blood gas should be obtained if there is doubt about the adequacy of venti- lation. At times, reintubation will be necessary.

2. Oxygenation: The pulse oximeter presently is the best way to assess oxygenation. The oximeter sensor is placed on the patient’s finger or ear. If possible, the oxygenation status of the patient should be followed during transportation to the recovery room.

Certainly, in the recovery room continuous pulse oximetry should

be employed until the patient is fully recovered. If oxygenation

saturation values are not adequate, then oxygen in the form of

nasal cannulae or mask should be administered. If, despite these

measures, concern remains about the adequacy of oxygenation,

then an arterial blood gas analysis should be carried out. A

decision can then be made as to whether the patient needs to be

reintubated or whether some lesser measures will correct the

problem.

3. Chest X-ray: There is no reason to perform a routine chest X- ray in the recovery room. However, patients in whom a central venous line was placed in the neck or upper chest during the pro- cedure and those in whom physical examination reveals poor breath sounds in one or the other lung, a chest film is indicated.

Also, patients with persistently low oxygen saturation values or who are ventilating poorly merit a chest film. The anesthesiolo- gist may request chest films in laparoscopic patients with severe subcutaneous emphysema that extend up to and include the neck to rule out barotrauma-related pneumomediastinum or pneu- mothorax. In this setting, provided that physical examination of the lungs is unremarkable and that the patient is well ventilated and oxygenated, chest X-rays are probably not required. An upright X-ray should be taken, if possible, to better demonstrate pneumothorax and pleural effusions.

4. Electrocardiogram: Routine EKGs are not necessary for healthy patients whose operation went smoothly and are without signs of cardiac instability. However, an EKG should be obtained in the immediate postoperative period if there are concerns about myocardial ischemia or infarction as well as if there is suspicion of a pulmonary embolus. In regards to the latter, an EKG may reveal right heart strain. Patients with a history of significant coronary artery disease, even if the case went smoothly, should also have an EKG.

II. Postoperative pain management. As already mentioned, pain must be controlled for the patient’s comfort and to permit adequate inspira- tion such that the patient is well ventilated and well oxygenated.

Although overmedication with narcotics can suppress respiratory function and must be avoided, it should be noted that it is far more common to undermedicate patients after surgery. In addition to the intraoperative pain measures already mentioned, one or several of the following should be ordered:

1. Patient-controlled analgesia: Usually morphine sulfate or demerol.

2. Intermittent intravenous or intramuscular injections of narcotics.

3. Intravenous or intramuscular Toradol or other appropriate NSAIDs (if not already given at the close of the operation).

4. Epidural analgesia: If an epidural catheter has been placed in the patient, it should be utilized. The anesthesiologist normally man- ages the use of these lines. This is an excellent way to control pain without suppressing respiratory function.

5. Oral pain medications in appropriate situations:

a. Narcotic-containing preparations b. Nonsteroidal antiinflammatory drugs

III. Pulmonary toilet, chest physical therapy, and pulmonary medications

1. As mentioned, abdominal incisional pain impairs postoperative

pulmonary function. An aggressive effort should be made, espe-

cially following major procedures, to educate the patient about

the dangers of postoperative atelectasis and infection. The patient and nursing staff should also be instructed as to how they can improve the patient’s pulmonary function.

a. Spirometer use for 5 minutes each hour while awake b. Coughing (after being medicated)

c. Deep breathing

d. Sitting in chair and ambulation

e. Nursing orders to make sure that patient does the above exercises

f. Where necessary, chest physical therapy (PT) should be ordered

i. Chest clapping combined with the above measures should improve pulmonary function.

ii. Nasotracheal suctioning helps to clear mucous plugs and to reinflate atelectatic segments.

iii. Determining vital capacity, FEV-1, and other pul- monary function parameters, at the bedside with a pocket spirometer, can help clarify a patient’s problem and also allow their progress to be monitored.

2. In patients with significant pulmonary disease, bronchodilators, aerosolized treatments, and other specific pulmonary medications may be needed. At times, steroids may be needed. Ideally, a pul- monologist would manage or assist with the pulmonary care of these patients. These patients are likely to require continuous oxygen, at least for the first few postoperative days.

C. Pulmonary Complications

I. The type of laparoscopic operation carried out will help determine the chances that a pulmonary complication may develop; some procedures are more likely to be accompanied by pulmonary problems than others.

Obviously, a patient’s baseline pulmonary function and their general medical condition are also important variables. The physician caring for the patient should be familiar with the patient’s history and should carefully review the operative course. The common complications that may be encountered are listed and briefly discussed below.

1. Atelectasis and consolidation: Atelectasis is probably the most common pulmonary complication encountered after surgery.

These complications are observed more frequently in patients who have undergone long operations or operations in the upper abdomen. Atelectasis can often be avoided with good pain control and aggressive chest physical therapy and pulmonary toilet.

a. Occasionally, a segment can fully collapse. Careful pul- monary auscultation should alert the physician to this pos- sibility, and a plain chest film should confirm the diagnosis.

Nasotracheal suctioning and bronchoscopy are usually

required to reinflate the segment in question.

b. An infiltrate or consolidation may develop in an atelectatic area. This is usually heralded by the development of a pro- ductive cough or secretions, fever, and an elevated white blood cell count.

i. If suspected, sputum cultures and Gram stains should be obtained and chest films taken.

ii. If evidence is found supporting the diagnosis, then an appropriate antibiotic agent should be started.

iii. An aggressive chest PT program should be initiated, if not already in place.

iv. At times, in a minority of cases, a bronchoscopy may be indicated.

2. Pneumothorax: Postoperative pneumothorax is a rare complica- tion that can occur in patients undergoing an upper abdominal operation during which mediastinal dissection has been neces- sary. It results most commonly from a pleural injury; direct pul- monary injuries are rare.

a. The pleural injury permits CO

to enter the hemithorax.

Because the patient is intubated and receiving positive pres- sure ventilation, the lung does not collapse. Postoperatively, in most cases, it is not necessary to place a chest tube because CO

is rapidly absorbed from the pleural space. The patient must be carefully observed, however, and serial chest films and frequent lung examinations should be carried out.

b. On the rare occasion when pneumothorax is due to direct pulmonary injury and an air leak develops from the lung, then a true pneumothorax (with air) will develop after surgery. The body is not able to absorb most of the compo- nents of air; therefore, a chest tube will be necessary. The surgeon should be alerted to this situation by a deterioration in the pulmonary examination and a worsening of the chest X-ray findings.

c. Very rarely, intubation or mechanical ventilation-related barotraumas can cause a pneumomediastinum or pneumoth- orax. A chest X-ray, if it demonstrates the former, will help establish the diagnosis. This diagnosis should be kept in mind especially in patients with significant pulmonary disease who demonstrate poor early postoperative pulmonary function.

3. Pleural effusion: A rare complication that can occur in patients

who undergo significant mediastinal dissection as well as in those

with preexisting significant heart or pulmonary disease. An effu-

sion may also develop in a patient who develops a subphrenic

abscess or collection. When suspected clinically, it should be con-

firmed by X-ray. The cause of the effusion must be carefully con-

sidered and then the appropriate treatment initiated. If small and

asymptomatic, then observation would most likely be appropri-

ate. Larger effusions, especially in symptomatic patients, may

require thoracentesis. Fluid obtained should be sent for the appro-

priate chemistry tests and for cultures.

4. Deep venous thrombosis and pulmonary embolus

a. The incidence and prophylactic measures: Laparoscopic proponents believe that the incidence of deep vein throm- bosis (DVT) and pulmonary embolus should be lower after a minimally invasive procedure because patients ambulate sooner and further than after open procedures. However, the argument can be made that the elevated intraabdominal pressure associated with pneumoperitoneum reduces lower extremity venous return, thus increasing the chances of venous stasis and DVT formation. There are not sufficient or adequate data, thus far, to settle this issue. Clearly, these problems do occur, rarely, after minimally invasive proce- dures. Therefore, the usual preventive measures should be undertaken.

i. Venous compression boots on the legs applied before the induction of anesthesia have been shown to reduce the incidence of DVT.

ii. Minidose heparin or similar agents given periopera- tively. The first dose should be given well before the incision is made. (Please see the chapter regarding pro- phylaxis against DVT.)

iii. Early ambulation.

b. Diagnosis: It is important to consider this diagnosis in patients who develop chest pain (most often pleuritic), dyspnea, tachypnea, apprehension, or hypoxia. It is impor- tant to rapidly workup patients suspected of having a pul- monary embolus. The following tests are helpful in this workup.

i. Arterial blood gases ii. Chest films iii. Electrocardiogram iv. Ventilation/perfusion scan

v. Pulmonary angiogram vi. Pulmonary arterial CT scan c. Treatment

i. Supplemental oxygen ii. Hemodynamic support iii. Intensive care setting

iv. Intravenous heparin: this should be started before con- firmation of the diagnosis in a patient with a high index of clinical suspicion.

v. Long-term treatment: coumadin therapy

vi. Placement of an inferior vena cava (IVC) umbrella or

filter (if anticoagulation contraindicated)

D. Summary

Although laparoscopic procedures are associated with less pain and more rapid ambulation and mobilization of patients, as well as shorter length of hos- pital stay, pulmonary complications still pose a threat in the postoperative period.

Respiratory function, similar to the situation after open surgery, is temporarily impaired postoperatively. Therefore, surgeons caring for patients who have undergone minimally invasive operations must motivate both patients and staff to make a concerted effort to maximize pulmonary function early after surgery.

They must also remain vigilant in regard to the development of pulmonary com- plications. When a pulmonary problem is suspected, a rapid evaluation and, when indicated, appropriate treatment must be promptly initiated.

E. Selected References

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Milsom JW, Bartholomäus B, Hammerhofer KA, Fazio V, Steiger E, Elson P. A prospec- tive randomized trial comparing laparoscopic versus conventional techniques in col- orectal cancer surgery: a preliminary report. J Am Coll Surg 1998;187:46–57.

Schauer PR, Luna J, Ghiatas AA, et al. Pulmonary function after laparoscopic cholecys- tectomy. Surgery 1993;114:389–399.

Schwenk W, Bohm B, Witt C, et al. Pulmonary function following laparoscopic or con- ventional colorectal resection: a randomized controlled evaluation. Arch Surg 1999;134:6–13.

Wittgen CM, Andrus CH, Fitzgerald SD, et al. Analysis of the hemodynamic and ventila- tory effects of laparoscopic cholecystectomy. Arch Surg 1991;126:997–1001.

Wittgen CM, Naunheim KS, Andrus CH, et al. Preoperative pulmonary function evalua-

tion for laparoscopic cholecystectomy. Arch Surg 1993;128:880–886.