Pain Management Guidelines for Blunt Thoracic Trauma

Abstract

I. STATEMENT OF THE PROBLEM AND QUESTIONS TO BE ADDRESSED Studies of the consequences and treatment of blunt thoracic trauma (BTT) remain hampered by a varying pathologic definition of the disease. Entities typically classified as BTT include chest wall lesions such as rib fractures, flail chest and soft-tissue contusion; intrapleural lesions such as hemothorax and pneumothorax; parenchymal lung injuries such as pulmonary contusion and lung laceration; and mediastinal lesions such as blunt cardiac injury.1,2 For purposes of this evidence-based review, we are concerned primarily with those injuries to the chest wall that produce their morbidity through pain and its associated mechanical ventilatory impairment. Thus, blunt chest trauma is defined here to include soft-tissue trauma and injuries to the bony thorax such as rib fractures and flail chest.3 Within the scope of this definition, the incidence and morbidity of BTT clearly remain significant. Rib fractures themselves are believed to be very common and have been documented in up to two thirds of cases of chest trauma.4,5 In another review, 10% of all patients admitted to one trauma center had radiographic demonstration of rib fractures.3 Isolated single or multiple rib fractures are one of the most common injuries in the elderly, at approximately 12% of all fractures, with an increasing incidence recorded as the population ages.6 The true incidence of bony thoracic injury may be underreported, as up to 50% of fractures may be undetected radiographically.7 For patients with blunt chest wall trauma, the morbidity and mortality are significant. These injuries are associated with pulmonary complications in more than one third of cases3 and pneumonia in as many as 30% of cases.3,8,9 Patients older than 65 years may be even more prone to major complications after blunt chest wall injury,3,10–12 with 38% respiratory morbidity from isolated rib fractures in another review.13 Because blunt chest wall trauma causes death indirectly, through pulmonary and nonpulmonary complications, the true mortality rate for these injuries is hard to evaluate. In one study, 6% of patients with blunt chest trauma died, and at least 54% of these deaths could be directly attributed to secondary pulmonary complications.3 An elderly group of patients suffered an 8% mortality rate from isolated rib fractures.13 Mortality of isolated flail chest has been as high as 16%.14 The incremental costs attached to pulmonary complications of blunt chest trauma have not been addressed in the literature but clearly would be measured in “intensive care unit (ICU) days” and “ventilator days,” both of which are expensive commodities. The treatment for injuries of the bony thorax has varied over the years, ranging from various forms of mechanical stabilization15,16 to obligatory ventilatory support.17–19 It is now generally recognized that pain control, chest physiotherapy, and mobilization are the preferred mode of management for BTT.9,20 Failure of this regimen and ensuing mechanical ventilation sets the stage for progressive respiratory morbidity and mortality.3,8,20 Consequently, several different strategies of pain control have been used, including intravenous narcotics, local rib blocks, pleural infusion catheters, paravertebral blocks, and epidural analgesia. Each of these modalities has its own unique advantages and disadvantages, and the overall most efficacious method has not previously been clearly identified. Subsequently, analgesic practices vary widely in this crucial setting. In one recent review, the majority of BTT patients were still managed with intravenous or oral narcotics.21 Other authors noted that epidural catheters were offered in only 22% of elderly BTT patients and 15% of a younger cohort.9 This review seeks to identify the optimal method(s) of pain control for patients with blunt chest trauma. The specific questions that are addressed using an evidence-based approach for outcome evaluation are as follows: Which patients with blunt chest trauma are at particular risk for respiratory morbidity caused by pain and deserve special attention to pain management? With consideration for safety, feasibility, and therapeutic effectiveness, what is the optimal method of pain control in blunt chest trauma? For the recommended modality/modalities, what technical recommendations can be made for the administration of analgesia in blunt chest trauma? A. Anesthetic and technology concerns. B. Nursing considerations. II. PROCESS A computerized search was conducted of the MEDLINE, EMBASE, and Cochrane Controlled Trials databases for North American and European English language literature for the period from 1966 through December 31, 2004. The initial search terms were “chest injuries,” “thoracic injuries,” “rib fractures,” and “flail chest.” These were cross-referenced for the secondary terms “analgesia,” “anesthesia,” and “pain.” This search initially yielded 213 articles. One hundred twenty-eight of these articles were excluded as being case studies, reviews, letters, or otherwise irrelevant to the questions being asked. This yielded a file of 85 articles for review. An additional 52 articles were obtained from the references of these studies, yielding a total of 137 studies for review and grading. Ninety-five of these were deemed appropriate for inclusion in the final evidentiary tables. The practice parameter workgroup for analgesia in blunt thoracic trauma consisted of five trauma surgeons, one trained as a thoracic surgeon, two anesthesiologists, and one trauma clinical nurse specialist. All studies were reviewed by two committee members and graded according to the standards recommended by the EAST Ad Hoc Committee for Guideline Development.22 Grade I evidence was also subgraded for quality of design using the Jahad Validity Scale published in Controlled Clinical Trials in 1996.23 Any studies with conflicting grading were reviewed by the committee chairperson and were all Grade I studies. Recommendations were formulated based on a committee consensus regarding the preponderance and quality of evidence. III. RECOMMENDATIONS A. Efficacy of Analgesic Modalities Level I Use of epidural analgesia (EA) for pain control after severe blunt injury and nontraumatic surgical thoracic pain significantly improves subjective pain perception and critical pulmonary function tests compared with intravenous narcotics. EA is associated with less respiratory depression, somnolence, and gastrointestinal symptoms than intravenous narcotics. EA is safe, with permanent disability being extremely rare and negligible mortality attributable to treatment. Level II Epidural analgesia may improve outcome as measured by ventilator days, ICU length of stay, and hospital length of stay. There is some Class I and adequate Class II evidence to indicate that paravertebral or extrapleural infusions are effective in improving subjective pain perception and may improve pulmonary function. Level III Although paravertebral or extrapleural analgesia is effective, there is an inadequate quantity of comparative evidence or information regarding safety to establish any recommendation with regard to overall efficacy. The information regarding both the effectiveness and safety of intrapleural and intercostal analgesia is contradictory, and experience with trauma patients is minimal. Consequently, no recommendation can be made regarding overall efficacy of this modality. B. Clinical Application of Pain Management Modalities to Treatment of Blunt Thoracic Trauma Level I Epidural analgesia is the optimal modality of pain relief for blunt chest wall injury and is the preferred technique after severe blunt thoracic trauma. Level II Patients with four or more rib fractures who are ≥ 65 years of age should be provided with epidural analgesia unless this treatment is contraindicated. Younger patients with four or more rib fractures or patients aged ≥ 65 years with lesser injuries should also be considered for epidural analgesia. Level III The approach for pain management in BTT requires individualization for each patient. Clinical performance measures (pain scale, pulmonary examination/function, arterial blood gases) should be measured as judged appropriate at regular intervals. Presence in elderly patients of cardiopulmonary disease or diabetes should provide additional impetus for epidural analgesia, as these comorbidities may increase mortality once respiratory complications have occurred. Intravenous narcotics, by divided doses or demand modalities, may be used as initial management for lower risk patients presenting with stable and adequate pulmonary performance, provided the desired clinical response is achieved. High-risk patients who are not candidates for epidural analgesia should be considered for paravertebral (extrapleural) analgesia commensurate with institutional experience. A specific recommendation cannot be made for intrapleural or intercostal analgesia based on the available evidence, but its apparent safety and efficacy in the setting of thoracic trauma has been reported. C. Technical Aspects of Epidural Analgesic Agents Level I There is insufficient Class I and Class II evidence to establish any specific techniques of epidural analgesia as a standard of care. Level II Combinations of a narcotic (i.e., fentanyl) and a local anesthetic (i.e., bupivacaine) provide the most effective epidural analgesia and are the preferred drug combinations for use by this route. Use of such combinations allows decreased doses of each agent and may decrease the incidence of side effects attributable to each. Nursing care of the patient with an epidural catheter should involve frequent monitoring of appropriate parameters at intervals based on institutional judgment. These parameters should include, but may not be limited to, respiratory function, sedation level and urinary retention for epidural narcotics, and fluid balance and motor strength for epidural anesthetics. Lower extremity weakness may be seen with excessive sympathetic block but may also indicate epidural hematoma or abscess and should prompt appropriate evaluation. It should be noted that epidural anesthetics may mask the sensory deficits caused by these mass lesions such that monitoring of motor function is especially important when such agents are used. Vital signs should be monitored frequently, as hypotension may occur as a result of sympathetic block and fever may indicate catheter site infection. The duration of epidural therapy should be individualized for each patient on the basis of the clinical situation, response to therapy, and anticipated therapeutic and adverse response to systemic alternatives. Epidural analgesia should be discontinued and the catheter removed when it no longer offers a benefit over systemic medications. The epidural catheter should be removed and the tip sent for culture if the site becomes erythematous or indurated or if there are signs of systemic infection such as fever, rigors, or leukocytosis. The indications for antibiotic therapy in possible epidural catheter/epidural space infections are beyond the scope of this guideline and additional resources should be referenced. Level III Although reliable literature describes the safe use of epidural analgesia on regular surgical floors, most victims of blunt thoracic trauma receiving this modality of treatment will have other primary indications for a higher level of care. Consequently, such patients in general should be nursed in a monitored setting with cardiac monitoring and continuous pulse oximetry. There is insufficient evidence at this time to make a recommendation regarding the use of continuous epidural infusion versus intermittent injection in trauma patients. IV. SCIENTIFIC FOUNDATION A. Historical Perspective The treatment of blunt thoracic trauma has undergone dramatic evolution over the twentieth century. In the first half of the century, the primary emphasis was on mechanical stabilization of the bony injury. This was first done by such external devices as sandbags or traction systems and later by various surgical methods such as wires or screws.24 After 1950, the concept of “internal pneumatic stabilization” with positive-pressure mechanical ventilation was developed.25 This became more prevalent and obligatory mechanical ventilation became the standard for chest wall trauma.26 The management of severe, blunt thoracic trauma evolved into the modern era with the publication of two studies in 1975. In a small series, Trinkle27 demonstrated that optimal pain control, chest physiotherapy, and noninvasive positive-pressure ventilation could avert the need for intubation and mechanical ventilation. Also in 1975, Dittman28 published the first in a series of three articles on pain management in blunt chest trauma. In the first study, 19 patients with multiple rib fractures and flail segments were treated with continuous epidural analgesia and intubation and mechanical ventilation were withheld. Using objective clinical criteria to monitor progress (e.g., vital capacity, respiratory rate, and tidal volume), 17 patients were successfully managed without positive-pressure ventilation. Dittman29 subsequently showed that 46 of 49 (94%) spontaneously breathing patients maintained a vital capacity greater than 13 mL/kg and avoided positive-pressure ventilation through the use of morphine analgesia by means of a thoracic epidural catheter. Other European studies demonstrated good clinical results with epidural analgesia in blunt chest wall injuries when combined with pulmonary toilet and selective mechanical ventilation.30–32 Thus, the management of blunt thoracic trauma today focuses on both the underlying lung injury and on optimization of mechanics through chest physiotherapy and optimal analgesia.30,33–36 The critical importance of measuring ventilatory function tests as an objective means of monitoring adequacy of this analgesia was emphasized by the authors of the early studies.33–36 Subsequent studies of pain management in blunt thoracic trauma patients would use the same methodology and additionally focus on comparisons between modalities and on objective outcome parameters.37–40 B. Modalities of Analgesia Intravenous Narcotic Intravenous narcotics have historically been the initial and most prevalent modality for relief of surgical and traumatic pain of all types. They are administered either by intermittent injection when pain is noted by the patient41 or continuous infusion.42 Most recently intravenous patient-controlled analgesia (PCA) has been developed to exploit the benefits of both methods.43,44 In this modality, a baseline intravenous infusion of morphine is provided and the patient may elicit an additional bolus for breakthrough pain. The obvious advantages of intravenous narcotics are ease of administration and monitoring by nursing without the risks of an invasive procedure or need for specialized personnel. The efficacy of this modality for blunt chest wall trauma is controversial. Intravenous narcotics have been shown to improve pain scores and vital capacity, yet some clinicians consider them inadequate in this setting.41,43 The disadvantages of systemic narcotics are the tendency to cause sedation, cough suppression, respiratory depression, and hypoxemia.42 Epidural Narcotics/Anesthetics Epidural analgesia (EDA) is a method whereby narcotics, anesthetic agents, or combinations thereof are introduced into the spinal epidural space at the thoracic or lumbar level to provide regional analgesia. This is accomplished by introduction of a polyvinyl catheter into the epidural space and delivery of agents by either a bolus, continuous infusion or, more recently, a demand system.32,39,45–50 The major advantage of EDA is its apparent effectiveness in the absence of sedation.32,39,45-50 EDA has been shown to result in an increased functional residual capacity, lung compliance, and vital capacity; a decreased airway resistance; and increased PO 2.45 Tidal volume is increased and chest wall paradox in flail segments in reduced.28 Patients with EDA generally remain awake and can cooperate with pulmonary toilet.28,47 There are numerous real and theoretical disadvantages to EDA. Insertion may be technically demanding. Epidural anesthetics can cause hypotension, particularly in the face of hypovolemia, and occasional epidural infection.46,47 Epidural hematoma, accidental entry into the spinal canal, and spinal cord trauma can also occur.45 Inadvertent “high block” may lead to respiratory insufficiency. By combining an epidural narcotic with the anesthetic agent, the dose of anesthetic can be decreased and these effects mitigated. However, the narcotic can cause nausea, vomiting, urinary retention, pruritus, and occasionally respiratory depression.28,42,51 The contraindications to EDA may prove problematic in the trauma patient. These include fever, coagulation abnormalities of even minor degrees, and altered mental status. There is some anecdotal concern that the bilateral analgesia effect may mask the symptoms of intra-abdominal injury.52 Finally, nursing intensity in monitoring for the effects of sympathetic block is somewhat more demanding than that for intravenous analgesia.53 Intercostal Nerve Block Intercostal analgesia or “intercostal nerve block” traditionally involves individual injections of local anesthetic into the posterior component of the intercostal space.45,54–56 Because of segmental overlap of intercostal nerves, it is necessary to induce block above and below any given fractured rib. Blocks of adequate scope have been shown to relieve pain with multiple rib fractures and improve peak expiratory flow rate and volume.57 However, the effect lasts only approximately 6 hours. As a unilateral block, hypotension is rare, and bladder and lower extremity sensation are preserved. The disadvantages of intercostal block include the need to palpate the fractured ribs for injection, and the need for multiple and repeated injections.45 Local anesthetic toxicity may theoretically occur because of the higher doses needed, and the incidence of pneumothorax increases with the number of ribs blocked.58 Also, inducing block for upper rib fractures is technically difficult because of the proximity of the scapula. Intercostal catheterization and continuous infusion has been successfully used and mitigates the need for multiple injections.43,54 However, the anatomic endpoint of catheter placement, piercing of the “posterior intercostal membrane,” is often unclear, raising the possibility of misplacement.59–61 The full anatomic limits of the spread of intercostal drugs is unclear.60,61 Intrapleural Anesthesia Intrapleural analgesia involves placement of a local anesthetic agent into the pleural space by means of an indwelling catheter.62 The produces a unilateral intercostal nerve block across multiple dermatomes by gravity-dependent retrograde diffusion of agent across the parietal pleura.45 As a unilateral modality, it has advantages similar to intercostal block regarding hypotension and bladder and lower extremity sensation. Successful use of this modality has been reported in blunt thoracic trauma patients.38,63–65 In terms of disadvantages, a significant amount of anesthetic may be lost if a tube thoracostomy is in place, which is often the case with trauma patients.66,67 This can be mitigated by temporary “clamping” of the thoracostomy, which in turn evokes concerns of tension pneumothorax. Conversely, in the absence of a tube thoracostomy, intrapleural catheter placement may cause a pneumothorax. The presence of hemothorax, also common in thoracic trauma patients, may theoretically impair diffusion of anesthetic.68 Because distribution of agent is gravity-dependent, effectiveness also varies with patient position, catheter position, and location of fractured ribs. Diffusion is most widespread in the supine position, which is not optimal for pulmonary function in the trauma patient.45 Conversely, the semiupright position may allow disproportionate diffusion inferiorly and adversely affect diaphragmatic function.69 Thoracic Paravertebral Block Thoracic paravertebral block involves the administration of a local anesthetic agent in close proximity to the thoracic vertebrae. This can be achieved by intermittent injection, bolus by means of a catheter, or continuous infusion, and produces a unilateral somatic and sympathetic block that extended over multiple dermatomes.31,43,66,70–76 Despite the fact that little recent investigation has been performed with this modality, its theoretical advantages are numerous. It does not require painful palpation of ribs, is not in conflict with the scapula, and is felt by some to be technically easier than epidural anesthesia.74,77 Because there is no risk of spinal cord injury as with EDA, this modality can be instituted on sedated or anesthetized patients. It has few contraindications and requires no special nursing management.73,74 The most common complications are vascular puncture, pleural puncture, and pneumothorax.45 The unilateral nature of the block makes hypotension rare, preserves bladder sensation, and allows monitoring of the lower extremity neurologic examination when necessary. The anatomic location of delivery for the various modalities of regional thoracic analgesia is illustrated in Figure 1.Fig. 1.: The anatomic location of delivery for the various modalities of regional thoracic analgesia. (From Karmakar MJ, Anthony MH, Acute pain management of patients with multiple rib fractures. J Trauma. 2003;54:615–625.)C. Support for Risk Assessment in Blunt Thoracic Trauma In 1993, Sariego78 showed that although Trauma Score and Injury Severity Score (ISS) predicted mortality in blunt thoracic trauma, neither identified those survivors who would develop pulmonary complications. Clearly, factors leading to pulmonary sepsis and/or mechanical ventilation set the stage for severe morbidity or mortality. Studies addressing risk assessment in blunt thoracic trauma are tabulated in Table 1 (found online at www.east.org). Extent of injury to bony thorax In a very large (n = 692) retrospective Class II series, Svennevig79 identified the presence of four or more rib fractures as an independent predictor of dramatically increased mortality. Patients with three or fewer fractures suffered only a 2.5% mortality, whereas those with four or more had a 19% mortality (p < 0.05). Similarly, in a large (n = 105,000) state registry review (Class III), Lee80 noted a 4% mortality rate for 2,477 patients with three or more rib fractures and a 1% rate for a similar group with two or fewer fractures (p < 0.001). The “two or fewer” fracture group had a statistically similar mortality to the control group in which the patients had no rib fractures. Finally, Ziegler,81 also in a large retrospective review (n = 711), analyzed mortality in relation to incrementally increasing number of rib fractures. He found a 5% mortality rate with one to two fractures, a 13% mortality rate with three to four fractures, and a 29% mortality rate with seven or more fractures. Analysis of these results did identify an inflection point for increased mortality at four fractures as noted in Figure 2. It should be noted that only 6% of patients had isolated rib fractures, and correction was not made for ISS, which tracked the number of fractures. Consequently, the contribution of the primary chest wall injury to mortality cannot not be isolated reliably.Fig. 2.: (From Ziegler V et al., Mortality and morbidity of rib fractures. J Trauma. 1994;37:975–979.)Age The salient Class II study was performed by Bergeron and associates82 in 2002. This group prospectively divided 405 patients with rib fractures into a “65 or above age group” and a “less than 65 age group.” The elderly patients had a significantly higher comorbidity rate (61% vs. 8%, p < 0.0001). Their analysis corrected for varying ISS, comorbidity, and a slight difference in mean fracture number. They identified a five-times greater risk of dying in the over 65 age group (9% vs. 19% morality, p < 0.01). This finding is most compelling because the elderly group had a significantly lower ISS despite their higher mortality (p < 0.031). Finally, an elegant attempt to relate the cumulative or synergistic effects of age and extent of chest wall injury was made by Bulger and colleagues83 in their retrospective (Class II) study of 458 blunt thoracic trauma patients. These authors also divided their population into a customary “65 or older group” and a “younger than 65 group” that were well matched in terms of injury severity. Pneumonia and mortality occurred twice as frequently in the older group (31% vs. 17%, and 22% vs. 10% respectively; both p < 0.01). Similarly, pneumonia and mortality tracked the number of rib fractures in both groups with a mortality odds ratio of 1.2 for each additional fractured rib at any age (p < 0.001). Not surprisingly, the rate of pneumonia increased more rapidly with increasing rib fractures for the elderly group as noted in Figure 3.Fig. 3.: Number of rib fractures versus incidence pneumonia for elderly and young populations. (From Bulger EM. Rib fractures in the elderly. J Trauma. 2000;48:1040–1047.)The critical finding in this study is that ventilator days, ICU days, hospital length of stay, and mortality increased more rapidly with increasing number of rib fractures for the elderly population. However, this difference was only statistically significant in the midrange of rib fractures, three through six, giving rise to a characteristic curve for these parameters (p ≤ 0.05). This distinctive pattern is illustrated in Figure 4 by the “number of fractures versus mortality” plot.Fig. 4.: Number of rib fractures versus percentage mortality for elderly and young populations. (From Bulger EM. Rib fractures in the elderly. J Trauma. 2000;48:1040–1047.)The authors postulate that this characteristic curve results from the poor tolerance by the elderly for “moderate” levels of injury, which are well tolerated by a younger cohort. At the upper extremes of chest wall injury, both groups do poorly and the curves again approach. All in all, the cumulative effect of age and severity of chest wall injury was powerful. In this study, an elderly person with six rib fractures had a mortality risk of 24% and a pneumonia rate of 35% versus 10% and 20%, respectively, for a younger patient (p < 0.05). Comorbidity Barnea and colleagues84 retrospectively reviewed 77 elderly (aged ≥ 65 years) with isolated rib fractures. They identified a strong relationship between nonsurvival and the presence of diabetes or congestive heart failure (p = 0.0095 and 0.001). Similarly, Alexander85 retrospectively reviewed 62 elderly patients with isolated rib. Complications occurred in 55% (n = 17) of patients with cardiopulmonary disease (“CPD+” for coronary artery disease or chronic obstructive lung disease) but in only 13% (n = 4) of those without (“CPD–”) (p < 0.05). Mortality occurred only in the CPD+ group (10% n = 3 p < 0.05). Upgrade in level of care was more common in the CPD + group. Length of ICU stay and hospital stay was double in the CPD+ group (p < 0.03). Conversely, Ziegler81 in a retrospective review of 711 patients, was unable to find a correlation between mortality and the comorbidities of chronic obstructive lung disease (n = 37), diabetes (n = 55), or hypertension (n = 155). There was also no increase in mortality noted for patients with coronary artery disease (n = 116) as defined by a previous myocardial infarction or treatment for angina or for patients with a previous stroke (n = 27). Specific statistical information is not provided in this study. Concurrent Extrathoracic Injury The cumulative effect of distant injury on the mortality of blunt thoracic trauma has rarely been specifically addressed. In Svennevig’s79 retrospective, Class II review of 652 blunt trauma patients previously discussed, the presence of one extrathoracic injury did not significantly increase mortality. However, the presence of two extrathoracic injuries increased mortality dramatically, and the highest death rate occurred in the thoracoabdominal injury subgroup (Table 2)Table 2: Mortality vs. Extrathoracic InjuryThis would not seem surprising, as the ISS has traditionally been accepted as an overall predictor of mortality. However, a number of studies suggest that the ISS may not be a valid predictor of risk of death in the elderly.86–88 Consequently, the incremental effect of distant injury on the mortality of blunt thoracic trauma becomes difficult to assess. D. Support for Choice of Pain Management Modality 1. Effectiveness of Analgesic Modalities Thoracic Epidural Analgesia Studies relating to epidural analgesia are summarized in Table 3 (found online at www.east.org). The greatest recent experience with invasive, regional pain management in the Western world, and in North America in particular, rests with EDA. Nevertheless, there is minimal compelling evidence that EDA improves outcome in trauma patients. Review yielded only one credible study to this end, that by Ullman et al.,39 a landmark Class I review that in 1989 randomized 28 isolated blunt chest trauma patients to receive continuous epidural narcotic or intermittent intravenous injection. The epidural group had significantly less ventilator days (3.1 ± 1.4 vs. 18.3 ± 8.1, p < 0.05), shorter ICU length of stay (5.9 ± 1.5 vs. 18.7 ± 5.3, p < 0.02), and shorter hospital length of stay (14.9 ± 2.2 vs. 47.7 ± 14.6, p < 0.02). The EDA group also had a tracheostomy rate of 7% versus 38% for the control group. Although the sample size was small, the study was adequately powered to the detect the differences indicated. In an early, Class II study, Gibbons30 in 1973 noted that 27 blunt chest trauma pati