Page 1539 - Hall et al (2015) Principles of Critical Care-McGraw-Hill

1058 PART 10: The Surgical Patient

even if FEV and FVC are normal, a DLCO should be obtained. If pre- were documented. A similar comparison of the laparoscopic versus open
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1
operative FEV or DLCO is <40% of predicted, these are independent approach resulted in quicker return of postoperative respiratory mechanics
1
predictors of postoperative pulmonary complications. These patients toward but not quite to normal compared to open cholecystectomy. A
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may benefit from cardiopulmonary exercise testing. This is a sophisti- review of over 300 patients following laparoscopic cholecystectomy showed
cated assessment of cardiopulmonary reserve and allows calculation of no major postoperative pulmonary morbidity in the entire group, despite
maximal oxygen consumption (V O 2 max). Risk of perioperative pulmo- the fact that 45 were deemed to be obese, including 18 who were morbidly
max measured. obese (BMI >45 kg/m ).
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nary complications can be stratified according the V O 2
max of >20 mL/kg are not at increased
Patients with a preoperative V O 2 Type of Anesthesia and Analgesia: Repeated attempts to demonstrate a
max of <15 mL/kg and
risk of complications; however, patients with V O 2 consistent decrease in postoperative pulmonary complications with
<10 mL/kg are at intermediate and high risk, respectively, for periopera- the use of regional anesthesia alone or in combination with general
tive pulmonary complications. anesthesia have failed. Anesthetic technique per se is not a significant
■ RISK MODIFICATION determinant of postoperative respiratory complications. All forms
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Perioperative Preparation: Standard preoperative preparation, includ- of regional anesthesia such as epidural local anesthetic, epidural nar-
cotic, intercostal nerve blocks, and paravertebral nerve blocks have
ing the use of intensive chest physiotherapy, bronchodilators, and beneficial effects on postoperative FEV , FVC, and partial pressure
1
appropriate use of antibiotics is considered routine practice in an ). However, these beneficial effects have not
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effort to reduce the risks of postoperative pulmonary complications. of arterial oxygen (Pa O 2
proved to alter outcome in terms of pneumonia, respiratory failure, or
High-risk patients who were assigned to receive a protocol of inten- death. Perhaps this is because the delayed reduction in FRC, resulting
sive pre- and postoperative therapy (including delay of surgery if in atelectasis and hypoxemia, remains largely unaffected by the intra-
indicated) had a 22% incidence of postoperative complications, com- and immediate postoperative analgesic regimens.
pared to 60% in a group in whom the preoperative preparation was Repeated studies of intraoperative positive end-expiratory pres-
at the discretion of the admitting physician. Aggressive pulmonary sure (PEEP) have failed to show benefit in normal patients; however,
therapy resulted in shorter hospital stay despite frequent delays of sur- the intraoperative application of PEEP 10 cm H O to morbidly obese
2
gery in the treatment group to improve pulmonary function. In the patients (BMI >40 kg/m ) resulted in an improvement in perioperative
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setting of coronary artery bypass surgery, patients identified as high oxygenation (110-130 mm Hg). However, these patients were studied
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risk for postoperative pulmonary complications were offered 2 weeks in the early postoperative period and this improvement may not have
of inspiratory muscle training (IMT). Compared to controls, these been maintained.
patients suffered half the incidence of serious postoperative pulmonary
complications including pneumonia. Those who suffered pneumonia Recommendations: Although several questions concerning accurate
in the IMT group also benefited through a shorter hospital stay than preoperative assessment for prevention of clinically significant pul-
pneumonia patients who had no respiratory muscle training. 56 monary complications remain unanswered, from available data a few
Despite the clinical application of deep breathing exercises, intermit- guidelines may be generated. Likely to benefit the patient preopera-
tent positive-pressure breathing (IPPB), and incentive spirometry, these tively are cessation of smoking (at least 4 weeks, preferably >8 weeks
treatments have not been shown to be independently successful in the abstinence), weight loss, and optimization of airway obstruction
prevention of postoperative pulmonary complications. Incentive spi- using bronchodilators. Intraoperative management options that may
rometry has been shown to be of benefit, but only in high-risk patients. benefit the patient include peripheral incision, limiting duration of
Pre- and postoperative chest physiotherapy per se is of value only in the surgery, endoscopic procedures, and the use of intraoperative PEEP.
treatment of established pulmonary atelectasis. However, high-risk mor- Postoperatively, good analgesia by the use of regional techniques and
bidly obese (BMI >40 kg/m ) patients may benefit significantly from the patient-controlled analgesia delivery devices has been shown to be
2
application of biphasic positive end-expiratory pressure noninvasively equally effective in reducing morbidity. Postoperative chest physio-
and prior to signs of respiratory distress. 57 therapy has proven value only for the treatment of atelectasis, but is
useful as part of a program to encourage deep breathing exercises.
Cessation of Cigarette Smoking: Continued smoking up to the time of
surgery is associated with a significant increase in mortality. Cessation ■ DIABETES MELLITUS
of smoking has been shown to result in a significant increase in FRC Diabetes mellitus is the most common endocrine disorder encountered
and reduced postoperative pulmonary complications. For maximum
risk reduction, the patient should stop smoking at least 8 weeks prior in the perioperative period, since it occurs in almost 5% of the general
population. Traditionally, diabetics presented for surgery for limb
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to surgery.
amputation and wound debridement, but owing to surgical advances
Site of Surgical Incision: Extremity surgical intervention leads to little in vitrectomy, cataract extraction, renal transplantation, and peripheral
alteration in lung volume. However, lower abdominal incision results vascular repairs, diabetic patients are frequently presenting for preopera-
in a 25% to 30% decrease in FVC and a mild decrease in oxygenation. tive assessment. Type I (insulin-dependent) diabetes mellitus comprises
Upper abdominal and thoracic surgery produces significant impair- approximately 25% of the diabetic population, and affects a relatively
ment of pulmonary ventilation and defense systems independent of younger population who are ketosis prone. They have no endogenous
the effect of anesthesia. insulin production and thus an absolute need for insulin. Type II (often
Maintenance of FVC is essential for effective secretion clearance and is and incorrectly called noninsulin-dependent diabetes mellitus) patients
reduced by 50% to 60% immediately following upper abdominal surgery. are older and often obese and have a decrease in the number and respon-
Gradual restoration of FVC over the next 5 to 7 days is usual. During siveness of insulin receptors, together with impaired insulin secretion,
the first 24 hours after upper abdominal or thoracic surgery, reductions features which are accentuated in the perioperative period. The stresses
occur in tidal volume (20%) and FRC (70%-80%) as a result of inci- of surgery that have already been discussed also include increases in
sion pain and reflex diaphragmatic splinting, resulting in rapid shallow endogenous glucocorticoids thus potential hyperglycemia.
breathing, absence of spontaneous sigh, and chest wall splinting. 58 Perioperative management problems arise additionally when type II
Laparoscopic surgery has revolutionized the postoperative care of diabetic patients who have now transitioned to high-dose insulin are
patients undergoing common surgical procedures such as cholecystectomy labeled “insulin requiring” and are managed as if they were ketosis prone.
and fundoplication. Comparing the open subcostal cholecystectomy to Type II diabetics often require several times the daily physiologic require-
the laparoscopic approach, significant improvements in FVC (52% vs 73% ment for insulin. If they are hypoglycemic, insulin is contraindicated. The
baseline), FEV (53% vs 72% baseline), and FEF (53% vs 81% baseline) ketosis prone type I requires continuous access to physiologic insulin.
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