Mapping of common rib fracture patterns and the subscapular flail chest associated with operative scapula fractures

BACKGROUND

Rib fractures occur in approximately 10% of trauma patients and are associated with more than 50% of patients with scapula fractures. This study investigates the location and patterns of rib fractures and flail chest occurring in patients with operatively treated scapula fractures. Novel frequency mapping techniques of rib fracture patterns in patients who also injure the closely associated scapula can yield insight into surgical approaches and fixation strategies for complex, multiple injuries patients. We hypothesize that rib fractures have locations of common occurrence when presenting with concomitant scapula fracture that requires operative treatment.

METHODS

Patients with one or more rib fractures and a chest computed tomography scan between 2004 and 2018 were identified from a registry of patients having operatively treated scapula fractures. Unfurled rib images were created using Syngo-CT Bone Reading software (Siemens Inc., Munich, Germany). Rib fracture and flail segment locations were marked and measured for standardized placement on a two-dimensional chest wall template. Location and frequency were then used to create a gradient heat map.

RESULTS

A total of 1,062 fractures on 686 ribs were identified in 86 operatively treated scapula fracture patients. The mean ± SD number of ribs fractured per patient was 8.0 ± 4.1 and included a mean ± SD of 12.3 ± 7.2 total fractures. Rib fractures ipsilateral to the scapula fracture occurred in 96.5% of patients. The most common fracture and flail segment location was ipsilateral and subscapular; 51.4% of rib fractures and 95.7% of flail segments involved ribs 3 to 6.

CONCLUSION

Patients indicated for operative treatment of scapula fractures have a substantial number of rib fractures that tend to most commonly occur posteriorly on the rib cage. There is a pattern of subscapular rib fractures and flail chest adjacent to the thick bony borders of the scapula. This study enables clinicians to better evaluate and diagnose scapular fracture patients with concomitant rib fractures.

LEVEL OF EVIDENCE

Diagnostic test, level IV.

A model for evaluating the biomechanics of rib fracture fixation

INTRODUCTION

High rates of morbidity and mortality following flail chest rib fractures are well publicized. Standard of care has been supportive mechanical ventilation, but serious complications have been reported. Internal rib fixation has shown improvements in pulmonary function, clinical outcomes, and decreased mortality. The goal of this study was to provide a model defining the biomechanical benefits of internal rib fixation.

METHODS

One human cadaver was prepared with an actuator providing anteroposterior forces to the thorax and rib motion sensors to define interfragmentary motion. Cadaveric model was validated using a prior study which defined costovertebral motion to create a protocol using similar technology and procedure. Ribs 4-6 were fixed with motion sensors anteriorly, laterally and posteriorly. Motion was recorded with ribs intact before osteotomizing each rib anteriorly and laterally. Flail chest motion was record with fractures subsequently plated and analyzed. Motion was recorded in the sagittal, coronal and transverse axes.

FINDINGS

Compared to the intact rib model, the flail chest model demonstrated an 11.3 times increase in sagittal plane motion, which was reduced to 2.1 times the intact model with rib plating. Coronal and sagittal plane models also saw increases of 9.7 and 5.1 times, respectively, with regards to flail chest motion. Both were reduced to 1.2 times the intact model after rib plating.

INTERPRETATION

This study allows quantification of altered ribcage biomechanics after flail chest injuries and suggests rib plating is useful in restoring biomechanics as well as contributing to improving pulmonary function and clinical outcomes.

[Innovated Judet Ribs Plates - Preclinical Study, First Clinical Experience]

PURPOSE OF THE STUDY Based on the experience with using the Judet plates in stabilization of rib fractures an innovated Judet plate was constructed in cooperation with the Development Department of Medin company. During the preclinical part of the project, following the construction of the new Judet plate, a surgical technique was elaborated. Subsequently, the clinical application of rib osteosynthesis with innovated plates was commenced. MATERIAL AND METHODS In the course of the last three years the innovated Judet rib plate including the instruments were constructed by the Development Department of Medin company in cooperation with the Trauma Centre and the Department of Surgery of the University Hospital Královské Vinohrady. The goal of the innovation was the changes in technical parameters of rib plates which are compared with the new plates of other companies: 1. Adequate plate stability along the rib axis. 2. Creation of fixation clips for a stable, but not traumatized fixation of the plate around the rib. 3. Decreased robustness of the plate with sufficient stiffness. 4. Working out of a new technique of plate fixation with the use of new instruments. 5. Ensuring plate fixation with cortical locking screws. In the preclinical part of the project osteosynthesis of the broken rib was performed with a plate on a chest model for the basic types of rib fractures. Subsequently, the plate was used for rib osteosynthesis in a cadaver. The goal of the new instruments was besides temporarily maintaining the rib fracture reduction also the subsequent temporary application of plates with the assistance of fixation tongs before the final fixation of plates. In 2017, the clinical part of the project on the stabilisation of flail chest with the innovative Judet plates was launched. This type of innovative Judet plates has so far been used in 3 patients. RESULTS As to the surgical technique of ribs osteosynthesis: The profile of the plate has been adapted to the rib profile and can be further adjusted to rib curvature, also the fixation shoulders of the plates have been reshaped. The innovated plate has been complemented with a new configuration of fixation clips and the possibility to fix the plate with locking screws. The used cortical locking screws enable appropriate stabilisation of plates. They were tested on a laboratory model of ribs and on a cadaver using the new set of instruments. The plates can be easily shaped with tongs. The anchorage of fixation clips is adequately provided for also by means of tongs. The plates can be fixed to the rib without any significant compression of intercostal nerves. The essential change of the innovated Judet plate is its weight, which meets the contemporary trends in construction of rib plates designed for anatomical fixation. The first experience with the innovated plates in flail chest injury confirmed the safety of the procedure for stable osteosynthesis of rib fractures. Adequate stability of the chest wall facilitated an early withdrawal of ventilatory support. Osteosynthesis of rib fractures with innovated plates performed in the first three patient was without complications, including in the postoperative period. DISCUSSION A series of prospective studies prove the correctness of the indications of early rib osteosynthesis in flail chest. Further indications for rib osteosynthesis are postinjury chest deformity, dislocation of rib fracture fragments with a lung injury, and malunion of rib fracture. According to these studies the surgical stabilisation of the chest is a safe and efficient method resulting in pain reduction, decrease of ventilatory support time, and also in reduced morbidity. For rib osteosynthesis anatomical plates, Judet plates and intramedullary plates are used. Our innovation of the Judet plate aimed to improve the technical parameters of the plate. The innovative Judet plate means a significant improvement in technical parameters and stands comparison with the plates of others companies, which are used in the Czech Republic. This is also evidenced by preliminary clinical results. CONCLUSIONS Surgical stabilisation of the flail chest segment is considered to be he method of choice in treating selected patients, leading to the improvement of respiratory function and shortening of the ventilatory support time. The new technical parameters of the plate, including its weight, new fixation clips, locking screws and instruments are the priorities of the innovated Judet plates. The innovation of Judet plates represents an important step towards the extension of indications for surgical stabilisation of the chest. Key words:innovative Judet plates, preclinical study, osteosynthesis of rib fractures.

Flail chest

Following standard weaning protocols, including sedation interruptions and spontaneous breathing trials, Mrs. W is successfully weaned from the mechanical ventilator and extubated on day 5 of hospitalization. Mrs. W is also weaned off of the PCA and achieves acceptable pain control with oral analgesic agents. Following education about the importance of nutrition, hydration, deep breathing, and aggressive mobility, she's discharged to a rehabilitation facility on day 8. She remains at this facility for 2 weeks, where she continues to be educated on using analgesics for pain control and mobilizing safely at home.

The management of flail chest

Flail chest is an uncommon consequence of blunt trauma. It usually occurs in the setting of a high-speed motor vehicle crash and can carry a high morbidity and mortality. The outcome of flail chest injury is a function of associated injuries. Isolated flail chest may be successfully managed with aggressive pulmonary toilet including facemask oxygen, CPAP, and chest physiotherapy. Adequate analgesia is of paramount importance in patient recovery and may contribute to the return of normal respiratory mechanics. Early intubation and mechanical ventilation is paramount in patients with refractory respiratory failure or other serious traumatic injuries. Prolonged mechanical ventilation is associated with the development of pneumonia and a poor outcome. Tracheotomy and frequent flexible bronchoscopy should be considered to provide effective pulmonary toilet. Surgical stabilization is associated with a faster ventilator wean, shorter ICU time, less hospital cost, and recovery of pulmonary function in a select group of patients with flail chest. Open fixation is appropriate in patients who are unable to be weaned from the ventilator secondary to the mechanics of flail chest. Persistent pain, severe chest wall instability, and a progressive decline in pulmonary function testing in a patient with flail chest are also indications for surgical stabilization. Open fixation is also indicated for flail chest when thoracotomy is performed for other concomitant injuries. There is no role for surgical stabilization for patients with severe pulmonary contusion. The underlying lung injury and respiratory failure preclude early ventilator weaning. Supportive therapy and pneumatic stabilization is the recommended approach for this patient subset.

New insights into the pathophysiology of flail segment: the implications of anterior serratus muscle in parietal failure

OBJECTIVE

The wisdom of surgery facing multiple and multi-focal ribs fractures (flail segment) remains controversial. By the present retrospective study, we sought to determine the advisability of surgery as well as the anatomical and biomechanical features of flail segment leading to secondary dislocation.

METHOD

From 1970 to 2000, 127 patients underwent flail segment osteosynthesis. Clinical charts, operative reports and imaging data were reviewed retrospectively. Rib osteosynthesis was carried out with Judet staple and Kirschner wires until 1980, since then it has been undertaken with sliding-staples-struts. Postoperative chest X-ray was carried out to classify the flail segments into anterolateral and posterolateral types according to the location of anterior and posterior rib fractures. Each type was then divided into three subgroups of primary parietal, secondary parietal and retreat indications that were inferred retrospectively from final indications of rib osteosynthesis.

RESULTS

The mean age of patients (ranging in age from 20 to 84 years) was 56+/-14.4 years with a male predominance (108/19). Seventy percent of flail segments was considered as posterolateral. The mean number of rib fractures per patient was 6+/-0.35. Rib osteosynthesis was undertaken with sliding-staples-struts in 70% of patients. The overall hospital mortality was 16%; it was subsequently reduced to 8% since sliding-staples-struts were used. The mean duration of ventilation was reduced from 5.8+/-0.76 days to 2.98+/-0.83 days with sliding-staples-struts. Seventy-seven percent of patients with posterolateral flail segment and primary parietal indication were extubated within the first 48 h postoperatively, whereas 46% of patients from other subgroups required ventilation for more than 5 days. Similarly, 83% of patients of the former subgroup returned to full previous level of activity compared with a rate of 52% for the latter subgroups. The flail segments were dislocated superoposteriorly for both anterolateral and posterolateral types, evoking the action of anterior serratus muscle.

CONCLUSIONS

The anterolateral and posterolateral flail segments are rendered susceptible to secondary dislocation through a complex set of factors, of which the action of anterior serratus muscle is obvious. Restoration of parietal mechanics by early surgical reduction/fixation is a reliable therapeutic option in selected patients and offers encouraging results.

Pathophysiology and management of the flail chest

Flail chest occurs when a series of adjacent ribs are fractured in at least 2 places, anteriorly and posteriorly. This section of the chest wall becomes unstable and it moves inwards during spontaneous inspiration. The physiological impact of a flail chest depends on multiple factors, including the size of the flail segment, the intrathoracic pressure generated during spontaneous ventilation, and the associated damage to the lung and chest wall. Treatment varies with the severity of the physiologic impairment attributable to the flail segment itself. Immediate surgical fixation may decrease morbidity, but conservative treatment with positive pressure ventilation is preferred when multiple injuries to the intrathoracic organs are present.

[Flail chest due to blunt trauma: clinical features and factors affecting prognosis]

BACKGROUND

We evaluated the clinical features of patients with flail chest, together with treatment results, and the factors affecting prognosis.

METHODS

The study included 34 patients (27 males, 7 females; mean age 41 years; range 15-61 years) who underwent treatment for flail chest. A retrospective analysis was made regarding the etiology, injury to the chest wall, pulmonary contusion, hemothorax and pneumothorax requiring chest tube, associated injuries, injury severity score (ISS), the presence of shock on admission, the amount of blood transfusions within the first 24 hours, treatment, and the results.

RESULTS

The most common cause of flail chest was traffic accidents (79.4%). Shock was detected in 41.2% and pulmonary contusions in 55.9%. Ventilatory support was required in 70.6%. The mean ISS was 36; mortality occurred in 32.4%. In seven patients without associated injuries and who did not receive ventilatory support, the mean ISS was 22.8 and all survived. However, in 18 patients with associated organ injuries, the mean ISS was 43.6, with mortality being 50% (p<0.05). Factors responsible for prolonged ventilatory support, pneumonia, and septic deaths included ISS above 31, associated fractures and injuries, blood transfusions, the need for chest tube, age equal to or above 50 years, and the presence of bilateral flail chest. The incidences of pneumonia and mortality were significantly less in patients treated with internal fixation (p<0.05).

CONCLUSION

Our data show that careful fluid management and effective pain control, stabilization of the chest wall, immediate ventilatory support and early weaning from ventilation are the mainstays of treatment.

Pulmonary function testing after operative stabilisation of the chest wall for flail chest

OBJECTIVE

This is a prospective evaluation of chest wall integrity and pulmonary function in patients with operative stabilisation for flail chest injuries.

METHODS

From 1990 to 1999, 66 patients (56 men, 10 women; mean age 52.6 years) with antero-lateral flail chest (> or =4 ribs fractured at > or =2 sites) underwent surgical stabilisation using reconstruction plates. Clinical assessment and pulmonary function testing were performed at 6 months following surgery.

RESULTS

Fifty-five (83%) patients had various combinations of injuries of the thorax, head, abdomen and extremities. Sixty-three (95.5%) patients underwent unilateral and 3 (4.5%) patients bilateral stabilisation with a median delay of 2.8 days (range 0-21 days) from admission. The 30-day mortality was 11% (seven of 66 patients). Immediate postoperative extubation was feasible in 31 of 66 patients (47%) and extubation within 7 days following stabilisation in 56 of 66 patients (85%). No plate dislocation was observed during the follow-up. The shoulder girdle function was intact in 51 of 57 patients (90%). Chest wall complaints were noted in 6 of 57 (11%) patients, requiring removal of implants in three cases. All patients returned to work within a mean period of 8 (range 3-16) weeks following discharge. Pulmonary function testing (n=50) at 6 months after the operation revealed a significant difference of predicted vs. recorded vital capacity (VC) and forced expiratory volume in 1s (FEV1) (P=0.04 and P=0.0001, respectively; Wilcoxon signed-rank test). The median ratio of the recorded and predicted total lung capacity (TLC) was shown to be significantly higher than 0.85 (P=0.0002; Wilcoxon signed-rank test), indicating prevention of pulmonary restriction.

CONCLUSION

Antero-lateral flail chest injuries accompanied by respiratory insufficiency can be effectively stabilised using reconstruction plates. Early restoration of the chest wall integrity and respiratory pump function may be cost effective through the prevention of prolonged mechanical ventilation and restriction-related working incapacity.

Determinants of rib motion in flail chest

We have previously developed a canine model of isolated flail chest to assess the effects of this condition on the mechanics of breathing, and these studies have led to the conclusion that the respiratory displacement of the fractured ribs is primarily determined by the fall in pleural pressure (Delta Ppl) and the action of the parasternal intercostal muscles. The present studies were designed to test the validity of this conclusion. A flail was induced in six supine anesthetized animals by fracturing both dorsally and ventrally the second to fifth ribs on the right side of the chest, after which the phrenic nerve roots were bilaterally sectioned in the neck. Sectioning the phrenic nerves caused a 34% decrease in Delta Ppl, associated with a 39% increase in parasternal intercostal inspiratory EMG activity (p < 0.05), and resulted in a marked reduction in the inspiratory inward displacement of the ribs. In three animals, the inward rib displacement was even reversed into a small outward displacement. When the airway was then occluded at end-expiration to increase Delta Ppl during the subsequent inspiration, all animals again showed a clear-cut inward rib displacement. These observations therefore confirm that in dogs with flail chest, the inspiratory displacement of the fractured ribs is set by the balance between the force related to pleural pressure and that generated by the parasternal intercostals. These observations also point to the critical importance of the pattern of inspiratory muscle activation in determining the magnitude of rib cage paradox in such patients.

Use of bilevel positive airway pressure ventilatory support for pathological flail chest complicating multiple myeloma

Multiple myeloma is a common disease that universally involves the skeletal system. Although rib involvement may occur, the development of pathological flail chest is rare. We describe the treatment and course of this condition in an elderly female, and the use of the bilevel positive airway pressure (BiPAP) ventilatory system in providing pneumatic stabilization, while definitive chemotherapy was given to heal the pathological fractures. Our experience with this patient suggests that, despite its dramatic clinical manifestation, the association of flail chest with multiple myeloma may not predict a poor prognosis. We have also found that pneumatic stabilization can be achieved by using the bilevel positive airway pressure ventilatory support through a tracheostomy.

Flail chest: a nursing challenge

Caring for a patient with a flail chest poses a significant challenge to the ED nurse. Performing serial evaluation, complicated pain management, and diligent pulmonary toilet will put your nursing skills to the test! Finding the time to do it in a busy emergency department ... well, that's a topic for another article.

Actions of the inspiratory intercostal muscles in flail chest

We have previously shown in dogs that the ribs in flail chest move paradoxically inward during inspiration but continue to move cranially. We have also shown that flail elicits, probably via an increased activation of the muscle spindles, a threefold to fourfold increase in external intercostal inspiratory EMG activity without inducing any changes in parasternal intercostal activity. Therefore, the present studies were undertaken to test the hypothesis that the persistent cranial motion of the fractured ribs resulted primarily from the action of the external intercostals. A flail was induced in seven supine anesthetized animals by fracturing both dorsally and ventrally ribs 3 to 6 on the right side of the chest, after which the external intercostal muscles in interspaces 1 to 7 were severed. Severing the external intercostals caused a small increase in the inspiratory inward displacement of the fractured ribs, from 2.76 +/- 0.31 to 3.25 +/- 0.38 mm (p < 0.05), but it did not affect the parasternal intercostal EMG activity or the cranial rib displacement (before, 3.61 +/- 1.03 mm; after, 3.22 +/- 1.43 mm; NS). However, when the parasternal intercostals in interspaces 1 to 7 were also denervated, the inspiratory inward displacement of the ribs increased markedly to 5.95 +/- 0.48 mm (p < 0.01), and their inspiratory cranial displacement was reversed into a 1.05 +/- 0.58 mm inspiratory caudal displacement (p < 0.01). We conclude, therefore, that in dogs with flail chest the respiratory displacements of the ribs are still primarily determined, besides pleural pressure, by the action of the parasternal intercostals. These observations also suggest that in anesthetized dogs, spindle-induced excitation of the external intercostals has little impact on the mechanical behavior of the ribs.

Experimental flail chest: ventilatory function with fixation of flail segment in internal and external position

The effect on ventilatory function of fixation of a flail segment in internal (FIP) and external (FEP) position and oxygen administration was studied in an experimental flail chest with pleural indemnity. Variations of tidal volume (TV), respiratory rate (RR), minute volume (MV), and arterial blood gases are reported. These parameters were measured in nine dogs in control and flail conditions (FC). The effect of FIP, FEP, and oxygen administration were studied.

RESULTS

Significant differences were found: TV decreased from control values to FC and from FC to FIP, but increased from FC to FEP. RR values increased from control to FC and from FC to FIP, but decreased from FC to FEP. MV values decreased from FC to FEP. TV, RR, and MV were not changed under oxygen administration. Hypoxemia or hypercapnia were not observed. It was concluded that FIP is deleterious for respiratory mechanics, whereas FEP improves ventilatory parameters.

Respiratory muscle response to flail chest

We have previously shown that flail chest in the dog causes an inspiratory inward displacement of the ribs and an increased inspiratory activity in the external intercostal muscles, and we have speculated that this increased activity is due to an increased spindle afferent activity. The present studies were designed to test this hypothesis. Twenty-nine supine anesthetized dogs were studied, and flail was produced surgically by fracturing ventrally and dorsally two to four contiguous ribs on the right side of the chest. Although flail elicited an increased inspiratory activity in the external intercostal and levator costae muscles in the disconnected segment of the rib cage, it did not alter the inspiratory activity in the diaphragm and parasternal intercostals. Expiratory activity in the triangularis sterni, internal intercostals, and transversus abdominis remained unchanged also, as did the inspiratory activity in the external intercostals on the left side of the chest. After flail, the normal inspiratory shortening of the external intercostal muscles in the disconnected segment was also reversed into an inspiratory muscle lengthening. However, when the fractured ribs were connected to the adjacent ribs so that the external intercostals were prevented from lengthening during inspiration, external intercostal and levator costae inspiratory activity was unaltered. These observations support the hypothesis that the increased external intercostal muscle activity seen in flail chest results primarily from an increased activation of the muscle spindles.

Cerebro-costo-mandibular syndrome

We describe two boys with the cerebro-costo-mandibular syndrome (CCMS). Both patients presented with Pierre Robin anomaly and respiratory insufficiency and died 12 hours and 10 months after birth. The first boy had muscular hypotonia, severe micrognathia, glossoptosis, short palate, preauricular tag, paraumbilical fibroma, and a small and narrow thorax. His chest roentgenographs showed marked hypoplasia of the first to tenth rib, multiple posterior rib-gaps in the only four ossified ribs. Tracheomalacia and stenosis of the left ureter was observed during autopsy. No structural cerebral anomalies were observed. Respiratory distress necessitated a tracheostomy in the second boy. He had severe micrognathia with glossoptosis and a cleft soft palate were noted. His chest roentgenograph showed a bell-shaped, small thorax with multiple dorsal rib-gap defects. CCMS is a rare disorder often associated with Pierre Robin anomaly. Chest roentgenographs show the typical posterior rib-gap defects, which are quite variable. CCMS usually occurs as an isolated event in a family. Of 41 reported families four reports describe horizontal and two describe vertical transmission of CCMS. This might imply genetic heterogeneity with autosomal recessive and autosomal dominant inheritance. Inter- and intrafamilial expression is variable. Careful family studies are necessary before genetic counseling is given.

Rib cage distortion in a canine model of flail chest

Although blunt chest injuries frequently lead to respiratory failure, the effects of flail chest on the mechanics of breathing have not been evaluated. In the present studies, we have measured the respiratory displacements of the ribs and sternum and the electromyograms (EMG) of the parasternal and external intercostal muscles in eight supine, anesthetized, spontaneously breathing dogs before and after the third to sixth ribs on the right side of the chest were fractured both dorsally and ventrally. After flail, the fractured ribs moved inward, rather than outward, during inspiration, but their inspiratory cranial displacement remained unchanged. The inspiratory outward and caudal displacement of the sternum, the inspiratory EMG activity of the parasternal intercostals, the pattern of breathing, and the arterial blood gases were also unaltered. However, the inspiratory EMG activity recorded from the external intercostals increased consistently to 327 +/- 101% of control (p < 0.05). These observations indicate that with flail chest, the disconnected segment of the rib cage shows paradoxical motion exclusively along the lateral axis; the increased external intercostal activation may account, at least in part, for the persistent inspiratory cranial motion of the ribs. These observations also suggest that the harmful effects of blunt chest injuries are related to pulmonary contusion and pain, rather than to flail chest per se.

A simplified method for stabilization of flail chest injuries in small animals

Two dogs and one cat with flail chest injuries were treated by a new technique of external thoracic wall stabilization using a single circumcostal suture for each affected rib and a splint device. Application of the splint device was quick and required minimal manipulation of the patient. Stabilization of the flail chest resulted in improved respiration in each animal. The splint device was left in place in two of the animals as the sole means of rib fixation. No evidence of infection or other adverse effects were noted with this technique.

Modern concepts in the management of flail chest

Seven patients with varying degrees of paradoxical chest wall movement (flail chest) were managed conservatively at the University of Port Harcourt Teaching Hospital with frusemide, methylprednisolone, non administration of crystalloid fluids and limitation of fluid intake. Patients showed considerable improvement within the first 24-48 hours which was sustained throughout the period of management. All seven survived and showed no signs of respiratory distress in the resting state or while performing simple exercise. One patient however had slight to moderate chestwall deformity.

[Clinical results of selective treatment for flail chest]

A better understanding in pathophysiology of flail chest has brought an evolution to the principles of it's management. The methods of stabilization changed from surgical to pneumatic measures and now, a concept of conservative treatment is recognized. Adhering to our protocol for flail chest, which essentially limits mechanical ventilation, we have prospectively treated 36 patients since 1981. The patient were divided into two groups according to their need for mechanical ventilation. There were 16 patients (44.4%) in a group treated in conservative manner and with no mechanical ventilation (Group A). There were 20 patients (55.6%) in a group treated by mechanical ventilation (Group B). Group A had 6.2% incidence of pneumonia, 3.6 days average stay in ICU and mortality rate of 0%. Group B had 75% pneumonia, 22.5 days average in ICU and 15% mortality. Group B patients required respiratory support for 14 days average, which was not reduced by surgical stabilization. Restrictive pulmonary disturbance in group A was milder than that of group B, and this again was not affected by surgical stabilization. We conclude that 40% of flail chest are controllable without mechanical ventilation and that the result of this conservative therapy is superior to any other treatments.

Chest wall distortion in patients with flail chest

Ventilators can impose resistive and elastic loads during subject-initiated and spontaneous breaths. Such loads might worsen the chest wall distortion that is characteristic of patients with flail chest. We have tested this expectation in nine patients with flail chest and four normal subjects. All subjects breathed for 3 to 5 min on each of the following modes: assist control, intermittent mandatory ventilation (IMV), continuous positive airway pressure 5 to 10 cm H2O by demand valve and by a high flow system (CPAP-HF), and spontaneously (T-piece). Pressure at the airway opening was evaluated as a measure of ventilator loading, and magnetometric displacements of the major chest wall dimensions were evaluated to assess chest wall distortion. In contrast to the normal volunteers, patients with flail chest displayed chest wall distortion during active inspirations. The patterns of distortion were variable among patients. The degree of distortion varied among ventilator modes; generally, there was a greater degree of chest wall distortion in breaths with greater loading. For example, distortion was greater during the spontaneous breaths taken on the IMV-mode than during spontaneous breaths taken on the T-piece. The CPAP-HF mode resulted in the least distortion, reversing chest wall distortion in five patients, improving it in two, and not changing the distortion in the remaining two. The improvements may be related to positive pleural pressures and to the minimal ventilator-imposed load of the high gas flow system. The distortion imposed by ventilators increases the work of breathing in these patients and may thus contribute to difficulty in weaning.

Rib fracture healing in experimental flail chest

Sixteen dogs were placed under general anesthesia and flail segments of the left chest were created by transecting ribs 7,8,9, and 10 anteriorly and posteriorly. Fractures were 10 cm apart so that a 10-cm flail segment encompassing four ribs was created. In Group I, the control (N = 5), the chest wall muscles were closed without any stabilization of the fractures. Group II (N = 5) had stabilization of both anterior and posterior fracture sites by polypropylene sutures. Group III (N = 6) had stabilization of the fractures in ribs 7 and 8 with 2.5-cm bone grafts taken from the left fourth rib. Ribs 9 and 10 were stabilized by polypropylene sutures. The study established a canine model for flail chest. It also showed that strut stabilization of rib fractures with bone grafts promotes better healing than suture stabilization. It suggests that using bone grafts taken from another rib to stabilize flail segments may be unsatisfactory since the rib used as a donor showed no signs of regeneration at 30 days.

Flail chest in closed chest trauma

The dramatic events following closed chest injury are often unpredictable and may be fatal. Chest injury is one of the commonest causes of road traffic accident deaths in Papua New Guinea. Flail chest is an important complication of closed chest injury which has not been described previously in the locally published literature. Flail chest, its complications and management are discussed with an illustrative case history.

Disorders of the chest wall and diaphragm

The clinical presentations of chest wall and diaphragmatic disorders are extremely diverse, and the attention of the emergency physician is often directed to a more obvious problem. The common denominator of these disorders is their effect on respiratory mechanics, a discussion of which precedes the review of specific disorders.

Experimental pendulum air in the flail chest

Conditions for occurrence of pendulum airflow under spontaneous ventilation were studied in adult dogs with flail chest experimentally constructed by removing three ribs and the chest wall. Pendulum air flow was recorded pneumotachometrically from outside the body by intubation to the bronchi. Despite objections to the occurrence of pendulum air by many investigators, we found that pendulum airflow occurs under various conditions. The main factors facilitating the occurrence included 1) Significant differences in airway pressure and ventilatory volume between the lungs on the injured and the opposite side. 2) A high frequency of respiration. 3) Increased resistance in the upper airway. The pendulum airflow occurred not only at the area of tracheal bifurcation but also in the peripheral bronchial airway in the ipsi-lateral thorax of the flail chest. However, pendulum airflow was observed only transiently coinciding with the time of change from one phase of respiration to the other, and volume of pendulum airflow was considered to be so minimal that it had no significant deleterious influence on the alveolar ventilation. In cases of marked dysfunction of the chest wall or with increasing upper airway resistance, pendulum airflow may disturb alveolar ventilation to a considerable extent.

Effects of contusion and flail chest on pulmonary perfusion and oxygen exchange

Localized pulmonary contusions were produced in the right lower lobes (RLL) of 12 anesthetized ventilated dogs, 6 of which had a flail segment in the chest wall over the RLL. Pulmonary oxygen exchange during ventilation with air and oxygen, and the lobar distribution of pulmonary perfusion by radioactive microsphere techniques were measured before and 3 h after contusion, and again after thoracotomy. These were compared to 12 noncontused dogs, 6 of which had a flail segment. Contusion produced an average decrease of 20 Torr in Pao2 during air breathing and an average increase in Qs/Qt of less than 5%, surprisingly small given the doubled weight and average 44% shunt calculated in the contused lobe after thoracotomy. No significant effect of flail or thoracotomy was found, indicating that the presence of an intact chest wall and lung-chest wall interdependence was not a major factor preventing a larger increase in intact whole-animal shunt of contused dogs. Rather, the small effect of this severe lobar injury on whole-animal shunt was due to a 30% decrease in RLL relative perfusion. This reduction was demonstrated to be localized to a smaller hemorrhagic subsection of the contused lobe.