Icahn School of Medicine at Mount Sinai, New York, NY, USA
Neurologic complications
The use of ICU pain assessment tools and daily sedation interruption have led to reduction in ICU length of stay (LOS) and patient mortality rates. The appropriate management of analgesia and sedation (see Chapter 2) can translate into significant improvements in outcome, a shortened duration of mechanical ventilation, a reduced incidence of delirium, and a reduced incidence of significant long‐term physical and cognitive dysfunction in ICU survivors.
Pain, anxiety, agitation, and PTSD have been widely studied in ventilated patients in the ICU. No one sedative agent has been reported to improve the risk of mortality among the critically ill or injured when compared in randomized control trials. For example, propofol may be associated with a shorter time to extubation and recovery from sedation when compared with midazolam. However, the risk of hypertriglyceridemia and hypotension is higher with propofol.
Propofol has also been associated with propofol‐related infusion syndrome (PRIS) which includes worsening metabolic acidosis, rhabdomyolysis, hypertriglyceridemia, hypotension, and arrhythmias. Some risk factors for PRIS are:
High propofol doses.
Prolonged infusion.
Liver disease.
Use of vasopressors.
Underlying mitochondrial disease.
Dexmedetomidine has been linked to a lower risk of drug‐associated delirium than alternative sedative agents, but it increases risk of bradycardia and hypotension.
Only a minority of critically ill patients require deep sedation, for conditions such as severe respiratory failure (e.g. ARDS), intracranial hypertension, and refractory status epilepticus.
Daily sedation interruption and use of sedation scales to target light sedation have been shown to reduce ventilator time and ultimately LOS. The Richmond Agitation‐Sedation Scale (RASS) and Riker Sedation‐Agitation Scale (see Chapter 2) have the best reliability and are recommended by clinical practice guidelines.
Critical illness polyneuropathy (CIP) and myopathy (CIM) are major complications of severe critical illness and its management. CIP/CIM affects both motor and sensory axons and, as a consequence, can prolong weaning from mechanical ventilation and physical recovery. Sepsis, systemic inflammatory response syndrome, and multiple organ failure play a crucial role in CIP/CIM. Prevention of risk factors such as high dose steroids, prolonged neuromuscular blockade, prolonged immobility, treatment of the underlying critical illness, and supportive care are the mainstay of treatment. Early mobilization and physical therapy in the ICU have been shown to prevent, as well as aid in treatment of, CIP. Early rehabilitation in the ICU is safe and associated with several benefits, including improvements in muscle strength, functional mobility, quality of life, and reduction in ICU delirium.
Cardiovascular complications
Cardiovascular complications such as myocardial ischemia and cardiac arrhythmias pose an acute and life‐threatening risk to ICU patients. Cardiac tachyarrhythmias can arise from a patient’s intrinsic cardiac disease, or from medications. Hemodynamic monitoring is essential in the ICU for careful patient management and to determine the etiology of changes in cardiac performance.
Bedside TTE use has gained popularity since the 1990s and has now become an important instrument in assessing the cause of and appropriate response to most hemodynamic disturbances.
We recommend the early use of goal‐directed bedside TTE in patients with hemodynamic instability, particularly those with increasing need of hemodynamic support to identify underlying treatable causes and help guide fluid resuscitation. Cardiac ultrasound allows intensivists to narrow the differential diagnosis and rapidly diagnose and initiate treatment.
Cardiac arrhythmias are a commonly encountered problem in the ICU. Preventable factors leading to arrhythmias include electrolyte abnormalities, catecholamine excess, and drug‐related adverse effects. Patients should be closely monitored for signs of cardiac ischemia with ECG and cardiac biomarkers. ECG monitoring for QT prolongation with close follow‐up can help in avoiding arrhythmias such as torsades de pointes.
QTc intervals should be particularly monitored in those receiving medications such as procainamide, amiodarone, certain antibiotics (erythromycin, pentamidine, ketoconazole), tricyclic antidepressants, and haloperidol.
Lastly, electrolyte abnormalities, particularly in hypokalemia, hypocalcemia, and hypomagnesemia, should be aggressively and appropriately repleted to prevent and often treat certain arrhythmias.
Hematologic complications
Blood transfusions are commonly administered to critically ill patients. Previous practices maintained hemoglobin thresholds of >10 g/dL in the critically ill. Recent guidelines based on multicenter randomized control trials indicate that target hemoglobin values of 7–8 g/dL are associated with equivalent or better outcomes in many patient populations and reduce the risk of infection, transfusion reactions and volume overload.
The 2016 American Association of Blood Banks (AABB) guidelines include the following recommendations for hemodynamically stable patients without active bleeding:
Hemoglobin <6 g/dL: transfusion recommended.
Hemoglobin 6–7 g/dL: transfusion generally likely to be indicated.
Hemoglobin 7–8 g/dL: transfusion may be appropriate in patients undergoing orthopedic surgery or cardiac surgery, and in those with stable cardiovascular disease, after evaluating the patient’s clinical status.
Hemoglobin 8–10 g/dL: transfusion generally not indicated, but considered for some (e.g. symptomatic anemia, bleeding, acute coronary syndrome with ischemia, and hematology/oncology patients with severe thrombocytopenia who are at risk of bleeding).
Hemoglobin >10 g/dL: transfusion generally not indicated except in exceptional circumstances.
Critically ill patients pose an increased risk of developing venous thromboembolism (VTE) due to their increased length of hospitalization, inactivity, immobilization, and often hypercoagulable states. Mortality associated with deep venous thrombosis is significantly high and often progresses to more serious complications such as pulmonary embolism.
Prophylaxis for VTE should be considered in all patients and initiated at the time of admission. The majority of ICU patients fall under the high risk criteria for developing VTE and pulmonary embolism, particularly those patients who have had an operation or have had major trauma. These patients should be initiated on prophylaxis with low dose unfractionated heparin (5000 U SC every 12 hours) or low molecular weight heparin (enxaparin 40 mg SC every day) as soon as possible, if not contraindicated by bleeding or coagulopathy. Intermittent pneumatic compression devices should be provided to all patients until anticoagulants can be safely initiated.
Gastrointestinal complications
Critical illness is associated with a severe catabolic stress state which contributes to the risk of infections, increased length of hospitalization, and mortality. The Society of Critical Care Medicine and American Society for Parenteral and Enteral Nutrition now recommend early enteral nutrition initiated between 24 and 48 hours of admission.
Enteral nutrition increases blood flow to the GI tract, decreases bacterial translocation, improves immune‐mediated response in sepsis, and improves overall survival.
There have been numerous prospective randomized trials performed in the critically ill comparing the effects of enteral versus parenteral nutrition. These trials showed that parenteral nutrition had a higher number of complications associated with infections (particularly pneumonia and central line infections), while enteral nutrition had a significant reduction in hospital LOS, cost of nutrition therapy, and infection rates.
Critically ill patients have a higher risk of developing stress‐related GI lesions due to hypoperfusion of the gastric mucosa, reduction in the protective factors of the mucosa, and increase in gastric acid secretion. These lesions may result in upper GI bleeding which is associated with an increased risk of death in the ICU.
In a large, prospective, multicenter trial of 2252 ICU patients by Cook et al., the mortality of patients with stress ulcer bleeding was 49% versus 9% in those with stress ulcers, but without an episode of GI bleeding. It also identified mechanical ventilation and coagulopathy as the two main risk factors associated with stress ulcer‐related bleeding.
Acid suppressive medications effectively decrease bleeding rates and are therefore recommended as prophylaxis in high risk patients. Proton pump inhibitors and histamine 2 receptor antagonists have been shown to prevent GI bleeding in the critically ill and are recommended in ICU patients with high risk such as those on mechanical ventilation, or with sepsis or septic shock, coagulopathy, and a history of upper GI bleeding in the past 12 months.
The routine use of stress ulcer prophylaxis does not reduce overall ICU mortality and therefore the need for stress ulcer prophylaxis should be re‐evaluated once the critical period has passed.
Renal complications
Hyponatremia remains one of the most common electrolyte disorders in the critically ill due to both excess fluid administration as well as impaired renal handling of fluids. Hyponatremia is a predictor of increased mortality in congestive heart failure and a marker of severity of illness in the general patient population. Daily monitoring of intravenous fluids and avoiding hypotonic solutions are key in preventing this electrolyte abnormality.
Central pontine myelinolysis (CPM) is an osmolar disruption in the brain that results in non‐inflammatory demyelination especially in the pons. CPM is a life‐threatening complication of rapid correction of hyponatremia. A conservative approach should be taken to correct hyponatremia by no more than 8 mEq/L over the first 24 hours, and no more than 15–20 mEq/L over 48 hours. Monitoring serum sodium frequently is crucial to the prevention of unrecognized rapid correction; when 3% saline is used, sodium should be monitored every 4 hours.
Hyperkalemia can result from renal insufficiency, rhabdomyolysis, burns, and/or trauma. It is also associated with commonly used medications such as digoxin, angiotensin converting enzyme inhibitors, angiotensin receptor blockers, heparin, NSAIDs, and succinylcholine. Treatment of hyperkalemia includes insulin plus dextrose, inhaled high dose beta‐agonist; calcium is administered in the setting of electrocardiography changes such as peaked T waves. Sodium polystyrene sulfate is another agent often used for treatment of hyperkalemia, however it should be noted that it has a very slow onset of action and has been linked to a complication of bowel necrosis.
Contrast‐induced nephropathy (CIN) is a common cause of hospital‐acquired acute kidney injury in the ICU. It leads to prolonged hospital stay, adverse clinical outcomes, and a 5.5% increased overall mortality. Critically ill patients are at a higher risk of developing CIN due to their greater severity of illness and comorbid conditions such as sepsis, hypotension, hypovolemia, and concomitant use of nephrotoxic agents. The mainstays for CIN prevention are hydration (pre‐ and post‐contrast) and the use of low osmolality contrast agents.
N‐acetylcysteine (NAC) has been theorized as a potential agent in preventing CIN. Recent trials have looked at the efficacy of NAC in preventing CIN in the ICU by comparing the incidence of acute renal impairment after administration of iodinated contrast with or without NAC treatment. The results suggest that NAC impedes the rise of serum creatinine but does not improve overall renal function. Additionally, NAC carries a risk of adverse side effects such as anaphylactoid reactions when administered intravenously. Its utility remains questionable and is therefore not recommended for the prevention of CIN.
Procedure‐related complications
Central venous catheterization (see Chapter 3) is a commonly performed procedure in the ICU. Complications vary with site and number of attempts at cannulation. They can be divided between infectious complications and mechanical complications such as arterial puncture, pneumothorax, and atrial/ventricular arrhythmias. Higher rates of infections have been reported with femoral sites versus either subclavian or internal jugular sites while the subclavian site has been associated with difficult to control bleeding.
Ultrasound‐guided catheter placement has shown clear evidence in reducing the rate of the above mentioned mechanical complications. We recommend the use of ultrasound‐guided central line placement whenever possible, including wire visualization by ultrasound prior to cannulation. A quick point‐of‐care ultrasound of the lungs can also be performed post‐procedure to assess for a pneumothorax. Telemonitoring should occur throughout the procedure for detection of premature ventricular complexes, particularly while introducing the guidewire and to monitor BP and oxygenation.
Endotracheal intubation (see Chapter 1) is a commonly performed procedure in the ICU. Circulatory collapse remains the most common and highest risk complication during the peri‐ and post‐intubation period, followed by hypoxia and aspiration. Unlike intubation performed in the operating room by an anesthesiologist, intubation performed in the ICU has not developed specific guidelines. The initial evaluation for any patient requiring airway management should begin with prediction of risk factors that would increase the risk of difficult intubation. The MOCOCHA score (Table 9.1) is a scoring system (>3 of 12 items present suggests higher risk) to predict a difficult airway. We recommend the early use of video‐assisted laryngoscopy (GlideScope™) for difficult intubation to avoid multiple attempts, airway trauma, esophageal intubation, and/or prolonged hypoxia.
* Score 0 to 12: 0 = easy airway, 12 = very difficult airway.
Airway management can be divided into three parts: pre‐, peri‐, and post‐intubation. The pre‐intubation period focuses on oxygenation with 100% non‐rebreather or non‐invasive ventilation such as high flow oxygen, which we prefer over non‐invasive bilevel positive pressure ventilation. Complications with BIPAP involve ineffective seal, lung hyperinflation, and introduction of air to the stomach.
In patients with GI bleed or those with emesis, we highly recommend nasogastric suctioning while setting up for intubation to remove any gastric residuals and reduce the risk of aspiration. The peri‐intubation period focuses on hemodynamic monitoring and anticipation of circulatory collapse with the administration of sedatives. Intravenous fluids should be initiated with standby vasopressor support to maintain mean arterial pressure above 65 mmHg.
The post‐intubation period should focus on the immediate confirmation of the endotracheal tube with capnography, initiation of appropriate sedatives, and the initial use of lung protective ventilation. The use of point‐of‐care ultrasound pre‐ and post‐intubation to assess lung sliding can be helpful in confirming adequate endotracheal tube placement and ruling out mainstem intubation while awaiting radiographic confirmation.
Infection control in ICU
Health care‐associated infections account for approximately 1.7 million infections and 99 000 deaths annually in the USA. The two most common device‐related infections encountered in the ICU are central line‐associated bloodstream infections (CLABSIs) and catheter‐associated urinary tract infections (CAUTIs).
A CLABSI is a bloodstream infection in a patient with a central venous catheter which cannot be attributed to an infection at any other site. CLABSIs are associated with increased hospital LOS, health care costs, and overall patient mortality. A 2013 meta‐analysis of the financial impact of health care‐associated infections in the USA found that CLABSIs had the highest financial cost in the health system at $45 814.
Implementation of prevention bundles and checklists have led to a 46% decrease in CLABSIs from 2008 to 2013. However, there are still an estimated 30 100 CLABSIs per year across the ICU and acute care facilities of the USA. An infection prevention checklist focuses on some of the main methods of CLABSI prevention including optimal site selection (avoiding femoral access sites), proper hand hygiene, use of chlorhexidine disinfectants, and use of maximal sterile barrier precautions during insertion.
The use of ultrasound guidance for placement of internal jugular catheter devices has been shown to reduce the risk of CLABSI and other non‐infectious complications and should be utilized when possible. Maintenance of these devices is important and may further reduce the rate of infection. Therefore, it is recommended to disinfect catheter hubs prior to access, maintain sterile dry dressing with routine dressing changes, and most importantly to remove the device as soon as it is no longer needed.
Urinary tract infections (UTIs) are common hospital‐acquired infections with an estimated 93 000 UTIs documented in acute care hospitals in 2011 in the USA. UTIs account for approximately 12% of nosocomial infections reported in the ICU. Urinary catheters pose additional risk factors in the elderly such as need for physical restraint, reduced mobility leading to risk of venous thromboembolism, and hematuria.
The use of procedure checklists and bundles similar to those utilized for CLABSIs have been shown to decrease the risk of CAUTIs and reduce the inappropriate use of urinary catheters. Hand hygiene and the use of aseptic placement of the urinary catheter are key in reducing the risk of infection. Maintenance of the catheter with a closed drainage system and prompt removal when no longer necessary are equally important in reducing CAUTI rates.
Ventilator‐associated pneumonia (VAP) occurs in 9–27% of all intubated patients. The incidence of VAP not only increases the mortality rate but is also associated with increased ventilator days and increased LOS.
Prevention strategies including patient positioning, equipment and hand hygiene, and bedside respiratory care (e.g. regular suctioning) have been shown to reduce VAP rates.
The use of oral chlorhexidine decreases bacterial colonization of oropharyngeal secretions and therefore the incidence of VAP in those intubated for the short term.
Please also refer to Chapter 44 (Infections Acquired in the Intensive Care Unit).
Reading list
Barr J, et al. Clinical practice guidelines for the management of pain, agitation, and delirium in adult patients in the intensive care unit: executive summary. Am J Health Syst Pharm 2013; 70(1):53–8.
Buendgens L, Koch A, Tacke F. Prevention of stress‐related ulcer bleeding at the intensive care unit: risks and benefits of stress ulcer prophylaxis. World J Crit Care Med 2016; 5(1):57–64.
Carson JL, et al. Clinical practice guidelines from the AABB: red blood cell transfusion thresholds and storage. JAMA 2016; 316(19):2025–35.
Chousterman BG, et al. Prevention of contrast‐induced nephropathy by N‐acetylcysteine in critically ill patients: different definitions, different results. J Crit Care 2013;5:701–9.
Cook DJ, et al. Risk factors for gastrointestinal bleeding in critically ill patients. Canadian Critical Care Trials Group. N Engl J Med 1994; 330:377–81.
De Jong A, et al. Early identification of patients at risk for difficult intubation in ICU: development and validation of the MACOCHA score in a multicenter cohort study. Am J Respir Crit Care Med 2013; 187:832–9.
Tamma PD, Srinivasan A, Cosgrove SE. Infectious Disease Clinics of North America. Antimicrobial stewardship. Preface. Infect Dis Clin North Am 2014; 28(2):xi–xii.
