General complications after surgical procedure

Ahmad Zubaidi, MBBS, MSc, FRCSC

POSTOPERATIVE FEVER• Quite common• Occurring in ~ 1/3 rd of patients after surgery. • Only a relatively small number of these are actually caused by infection. • Fevers that are caused by infections (e.g., pneumonias, wound infections, or

urinary tract infections) tend to – reach higher temperatures (> 38.6°C)– usually are associated with moderate elevation of the white blood cell (WBC) count 3 or more days

after operation– typically extend over consecutive days.

• Noninfectious causes of postoperative fevers include components of the inflammatory response to – surgical intervention– Re-absorption of hematomas– ??? (possibly) atelectasis

POSTOPERATIVE FEVER• Checking the WBC count is the only needed investigation

– A focused approach based on well-directed questioning and a careful physical examination to obtain the highest diagnostic yield.

– Coughing, sputum production, and respiratory effort should be noted– the lungs should be auscultated for rales. – All incisions should be inspected for erythema and drainage– current and recent I.V. sites should be checked for evidence of cellulitis. – If a central line has been placed, particularly if it has been in place for several days, the possibility

of a line infection should be considered. – Patients who have undergone prolonged nasogastric intubation may have sinusitis, which is most

readily diagnosed through computed tomography of the sinuses.

• Workup for fever – chest x-ray– sputum cultures– Urinalysis– blood cultures– CT of the abdomen (after procedures involving laparotomy especially bowel resections; where

intra-abdominal abscess is a possible complication).

POSTOPERATIVE FEVER1. Malignant hyperthermia (MH)

A. occurs after exposure to agents such as succinylcholine and some halothane-based inhalational anesthetics. B. The presentation is dramatic, with rapid onset of increased temperature, rigors, and myoglobinuria related to myonecrosis. C. Medications must be discontinued immediately and dantrolene administered (2.5 mg/kg every 5 minutes) until symptoms subside. D. Other supportive measures and aggressive active cooling are also implemented, such as alcohol baths, packing in ice, or the use of fans. E. For cases of severe malignant hyperthermia, the mortality rate is nearly 30%.

2. Neuroleptic malignant syndrome (NMS) A. All classes of neuroleptics [dopamine (D2)-receptor antagonists] are associated with NMS, and dopamine receptor blockade is

considered to be the cause of NMS. B. NMS is more likely to develop following initiation of neuroleptic therapy or an increase in the dose. C. The onset can be within hours, but on average it is 4 to 14 days after initiation of therapy. However, NMS can occur at any time during

neuroleptic use, even years after initiating therapy. D. Symptoms include muscle rigidity, tachycardia, urinary incontinence, hemodynamic lability, respiratory distress, and changes in mental

status. As with MH, treatment begins with discontinuing the offending medication and initiation of active cooling measures. E. Dopamine agonists appear to decrease mortality and shorten the course of NMS, so bromocriptine and amantadine are used to control

the syndrome's manifestations. F. Mortality reaches 5%.

3. ThyrotoxicosisA. can occur after: surgery, as well as with childbirth, severe infections, and undiagnosed Graves' disease. B. Hyperthermia (>40°C), anxiety, copious diaphoresis, congestive heart failure (present in about one fourth of episodes), tachycardia

(most commonly atrial fibrillation), and hypokalemia (up to 50% of patients)C. The treatment of thyrotoxicosis is to control the crisis itself.

I. Glucocorticoids, propylthiouracil, beta blockade, and iodide are delivered in an emergent fashion. II. RehyderationIII. Paracetamol (Acetaminophen) IV. Cooling

PNEUMONIA• Respiratory infections in the postoperative period are generally considered nosocomial

pneumonias and, as such, are potentially serious complications• Incidence varies significantly, ~ 1.5%• The 30-day mortality ~ 21%

• Significantly risky procedures: – Thoracic procedures– Upper abdominal procedures– Abdominal aortic aneurysm repair– Peripheral vascular procedures– Neurosurgical procedures

• Patient-specific risk factors: – Age >60 – Recent alcohol use– Dependent functional status– Long-term steroid use– A 10% weight loss in the 6 months preceding the operation.

PNEUMONIA• The diagnosis is based on

– Index of suspicion– Findings from the history and physical examination (e.g., fever, shortness of breath, hypoxia, productive cough, and

rales on lung auscultation)– Imaging (CXR)– Laboratory evaluation

• Appropriate workup, directed by the clinical findings– Typically starts with chest x-rays (preferably in both posteroanterior and lateral views, if possible) – Sputum cultures– Sometimes accompanied by:

• CT scanning of the chest • Bronchoscopy with bronchoalveolar lavage (which may be useful in directing antibiotic therapy when sputum cultures

are nondiagnostic)

• Empirical broad-spectrum antibiotic therapy can be initiated before the causative organism is identified– this practice has been shown to reduce mortality. – Piperacillin-tazobactam, which is effective against Pseudomonas aeruginosa, is commonly used for this purpose– However, when Gram's staining of the sputum identifies gram-positive cocci, vancomycin or linezolid may be used

initially instead.– Once the causative organism is identified, specific antibiotic therapy directed at that organism is indicated, as in

treatment of other infectious processes. – Drainage of parapneumonic effusions may also be necessary, and this measure may be helpful in diagnosing or

preventing the development of empyema.

SURGICAL SITE INFECTION(SSI)• SSI is one of the most common postoperative complications and may

occur after virtually any type of procedure

• Rates of infection vary widely (1% - 20%)

• Depending on – The procedure performed– The classification of the operative wound (clean, clean-contaminated,

contaminated, or dirty)– A host of patient-related and situation-specific factors

• The majority of SSIs are caused by skin-based flora– Most commonly gram-positive cocci (e.g., staphylococci)– Gram-negative infections are also commonly seen after GI procedures– Anaerobes may be present after pharyngoesophageal procedures.

SURGICAL SITE INFECTION(SSI)• Prompt recognition of the signs and symptoms is the key to successful management.

– Regular examination of the wound, particularly in the setting of postoperative fever, is critical. – Erythema and induration indicate cellulitis– Active drainage of pus from the wound. – A more subtle sign is pain that is greater than expected, especially when the pain seems to be

increasing several days after operation.

• Treatment– Open and drain the wound (which is easily done at the bedside or in the clinic in most cases)– Allow it to heal via secondary intention. – Generally, wet-to-dry dressing changes with saline are employed– The use of antibiotics depends on the presence and degree of cellulitis. – The initial choice of an agent should be guided by the likelihood that particular organisms will be

present, which is estimated on the basis of the site of the operation and the type of procedure being performed.

– Whenever possible, any purulent material in the SSI should be cultured; this step may permit more targeted antimicrobial therapy

DEEP VEIN THROMBOSIS• In the absence of appropriate prophylaxis

– The incidence of DVT may be as high as 30% in abdominal and thoracic surgery patients– Fatal pulmonary embolism (PE) may be as high as 0.9%.

• Major risk factors for DVT and PE– The operation itself– Physical immobility– Advanced age– The presence of a malignancy– Obesity – A history of smoking.

• DVT should be suspected postoperatively whenever a patient com plains of lower-extremity pain or one leg is noticeably more swollen than the other.

• The gold standard for diagnosis remains a venous duplex examination, which has a sensitivity of 97% for detecting DVT of the femoral and popliteal veins.

• In most cases, treatment involves starting a heparin infusion (typically without a loading bolus in the postoperative setting), targeting a partial thromboplastin time (PTT) that is double to triple the normal PTT (i.e., approximately 60 to 80 seconds), and then switching to warfarin therapy when the patient is stable and able to tolerate oral medications.

PULMONARY EMBOLISM• PE should be suspected:

– If postoperative patient experiences a decrease in oxygen saturation or shortness of breath– This decrease may be accompanied by:

• Chest pain• Tachycardia • Diaphoresis

• The principal means of diagnosing acute PE is spiral CT. – This modality has relatively wide availability– It can be performed fairly rapidly– It has a sensitivity of 53% to 100% and a specificity of 81% to 100%. – Greater diagnostic yield may be obtained by combining spiral CT with a lower-extremity venous duplex

examination

• When PE is suspected– It may be appropriate to start heparin therapy even before the diagnosis has been confirmed, depending on

• The degree of suspicion • The relative risk anticoagulation may pose to the patient.

– Low-molecular-weight heparins (LMWHs) are also generally safe and effective– ?? LMWH effect cannot be turned off I less useful in the period after operation– In patients with massive PE

• surgical embolectomy or suction-catheter embolectomy may be considered, as conditions warrant. – Thrombolytic therapy is generally contraindicated in the postoperative setting.

CARDIAC COMPLICATIONS• Cardiac dysrhythmias may occur after a wide variety of surgical procedures• They are most common after cardiac operations. • Predisposing factors and possible causes are numerous and various

– Underlying cardiac disease– Perioperative systemic stress– Electrolyte and acid-base imbalances– Hypoxemia– Hypercarbia– Treatment generally involves first achieving hemodynamic stability and then converting the rhythm back to

sinus if possible.

• Supraventricular tachycardias (SVTs) – Dysrhythmias most commonly seen in the postoperative period– Occurring after ~ 4% of noncardiac major operations. – Atrial fibrillation and atrial flutter account for the majority of SVTs.– Ventricular rate control may be achieved pharmacologically by infusing diltiazem. – Digoxin has long been used for this purpose, but it is less effective in acute settings than diltiazem – Amiodarone, which is used to treat ventricular dysrhythmias may also be used to restore sinus rhythm

postoperatively– Cardioversion, when pharmacologic rate control is not possible and hypotensive patient

CARDIAC COMPLICATIONS• ~ 1/3rd of patients who undergo noncardiac surgery have some degree of

coronary artery disease and thus are at increased risk for perioperative MI• The incidence of coronary artery disease is even higher in certain

subpopulations, such as patients who undergo major vascular procedures• ~ 50% of all MIs occurring in surgical patients are caused by increased

myocardial oxygen demand in the face of inadequate supply resulting from factors such as– Fluid shifts– Physiologic stress– Hypotension – The effects of anesthesia. – The majority of cardiac ischemic events occur in the first 4 days of the

postoperative period.

CARDIAC COMPLICATIONS• Peri-operative beta blockade for patients at risk for MI is now routine. • It yields significant risk reductions in both cardiac morbidity and

mortality, regardless of the type of surgery being performed.

• Beta blockade should be:– Initiated preoperatively– Delivered at the time of surgery– Continued postoperatively for up to 1 week

CARDIAC COMPLICATIONS• Diagnosis of postoperative MI is complicated

– 95% of patients who experience this complication may not present with classic symptoms (e.g., chest pain)

– ECG changes brought on by the stress of the perioperative period (including dysrhythmias) – Ultimately, the most useful signal is a rise in the levels of cardiac enzymes, particularly troponin-I– Cardiac enzyme activity should be assessed whenever there is a high index of suspicion for MI or a

patient is considered to be at significant perioperative risk for MI

• Treatment of postoperative MI – Focuses on correcting any factors contributing to or exacerbating the situation that led to the

event (e.g., hypovolemia or hypotension). – Antiplatelet agents (e.g., aspirin) are sometimes given– Thrombolytic therapy is avoided because of concerns about postoperative bleeding. – Acute percutaneous coronary intervention is also associated with an increased risk of bleeding,

but it has nonetheless been used successfully in the perioperative setting and is recommended by some physicians

– Beta blockade is often advocated as a means of treating postoperative MI