Management of traumatic flail chest in intensive care unit: An experience from trauma center ICU.

BACKGROUND/AIM: The thoracic injury and related complications are responsible for upto 25% of blunt trauma mortality. This study is designed to compare these two popular ventilation modes in traumatic flail chest. MATERIALS AND
METHOD: A total of 30 patients with thoracic trauma, aged 18-60 years, were enrolled in this study for a period of 1 year. The Thoracic Trauma Severity Score (TTSS) was used for assessing the severity of chest injury. Patients were divided into two treatment groups: one recieved endotracheal intubation with mechanical ventilation (ET group, n = 15) and another recieved noninvasive ventilation (NIV group, n = 15). All patients were observed for the duration of ventilatory days, complications such as pneumonia and sepsis, length of the stay in ICU, and mortality. Statistical analysis was done using statistical software SPSS for windows (Version 16.0).
RESULTS: There were no significant differences in age, sex, weight, and length of the stay in ICU in between the two groups. Rate of complications was significantly higher in ET group. Oxygenation was significantly improved in NIV group within 24 hr, later it become equivalent to the ET group patients while the pCO2 level was significantly lower in ET group compared with NIV group. Analgesia in both the groups is maintained to keep the visual analog scale (VAS) score below 2 and was comparable in both the groups.
CONCLUSIONS: The endotracheal intubation is also associated with serious complications as compared to NIV. The use of NIV in appropriate patients decreases complications, mortality, length of the stay in ICU, the use of resources, and cost.

Introduction

Trauma is the “major killing factor” in young patients of less than 45 years of age, especially in the developing countries.[1] Among all the trauma cases, blunt chest trauma is associated with a high risk of morbidity and mortality. The thoracic injury and related complications are responsible for upto 25% of blunt trauma mortality.[2] It involves threat to the airway, breathing, and circulation. Rib fractures constitute a major part of blunt chest trauma, and each additional rib fracture is associated with an increasing likelihood of developing complications. Each additional rib fracture in the elderly population increases the odds of mortality by 19% and of developing pneumonia by 27%.[34] The flail chest is the most severe type of injury among blunt thoracic trauma, and the mortality rate ranges from 16% to 17%.[56]

In India, Kulshrestha et al. conducted a study with a sample of 1,359 chest trauma patients; among them, 49% had rib fractures, 20% had pneumothorax, 12% had lung contusion, and 6% thoracic vascular injury. The mortality rate was found to be 9.4%, of which 5.6% had mortality in first 24 hours.[7]

The respiratory complications due to rib fractures are a consequence of splinting of the thorax from pain and mechanical instability leading to inadequate ventilation.[8] Therefore, the patients with flail chest need medical aid for two main indications: mechanical ventilation and pain relief. These patients have an increased risk for development of pneumothorax, haemothorax, pulmonary contusion, pneumonia, pleural effusion, acute respiratory distress syndrome (ARDS), pulmonary embolism, and atelectesis.[9101112] That is why it is important to know about them, because we target our interventions to reduce the risk of complications in flail chest patients. The risk prediction can be done by using clinical and radiographical parameters which help in prevention of complication. The management protocol includes multidisciplinary approach using pain management, pulmonary hygiene, and ventilatory management. The ventilatory management planned for the patient depends on patients’ clinical and ABG parameters. There are two main methods commonly used nowadays for ventilatory support: noninvasive and invasive. They assist patient's effort and improve overall lung functions. This study is designed to compare these two popular ventilation modes in traumatic flail chest. We measured the oxygenation status, complications, length of stay in ICU, mortality, and outcome of higher TTSS in noninvasively ventilated versus invasively ventilated patients.

Materials and Methods

A total of 30 patients with thoracic trauma aged 18–60 years were enrolled in this study for a period of 1 year. Patients with Glasgow coma scale (GCS) score >12, a respiration rate >35/min, accessory muscle use or paradoxical abdominal contraction, SpO2 <90% with FiO2 0.5%, pO2 <80%, and computed tomography (CT) scan of thorax with a flail segment were included in the study. Patients with traumatic brain injury, with severe hemodynamic instability, who had emergency gastrointestinal surgery following admission, who had inability to protect airway or facial trauma, and who were uncooperative to use facemask were excluded from the study. The clinical parameters including heart rate (HR), mean arterial pressure (MAP), respiratory rate (RR), SpO2, arterial blood gas analysis, and CT scan of thorax were assessed at time of admission to the intensive care unit.

The Thoracic Trauma Severity Score (TTSS) is used for assessing the severity of chest injury [Table 1]. It is a 25-point score with five parameters: P/F ratio, rib fractures, contusion, pleural involvement, and age.[13]

Table 1

The Thoracic Trauma Severity Score (TTSS) for assessing the severity of chest injury

Grade	PaO2/FiO2	Rib fracture	Contusion	Pleural effusion	Age	Point
0	<400	0	None	None	<30	0
I	300-400	1-3	1 Lobe (U/L)	PT	30-41	1
II	200-300	3-6	Lobe (B/L) or <2 lobe (U/L)	HT/HPT (U/L)	42-54	2
III	150-200	>3 (B/L)	<2 Lobe (B/L)	HT/HPT (B/L)	55-70	3
IV	<150	flail chest	<2 Lobe (B/L)	TPT	>70	5

PT: Pneumothorax; HT: Hemothorax; HPT: Hemopneumothorax

Patients were divided into two treatment groups: one recieved endotracheal intubation with mechanical ventilation (ET group, n = 15) and another received noninvasive ventilation (NIV group, n = 15). The ET group patients were intubated with a 7.5–8.5 mm internal diameter (ID) endotracheal tube. Initial ventilator settings with assist-control mode to generate a tidal volume of 6–8 mL/kg, RR below 25%, and plateau pressure <30 cm H2O. Positive end expiratory pressure (PEEP) gradually increases to maintain SpO2 >90% with an Fi of 0.6. These patients started with sedation infusion of midazolam and ferntanyl injections. The weaning protocol was to shift Pt on intermittent mandatory ventilation followed by pressure support ventilation. Patients extubated if they maintain a RR <25, SpO2 >95%, and pO2 >80 with an Fi = 0.4.

The patients in NIV group were put on biphasic positive airway pressure (BiPAP) mode initially. Inspiratory positive airway pressure (IPAP) was set at 8 cm H2O and EPAP at 4 cm H2O. IPAP titrated to achieve a tidal volume of 6 mL/kg and respiration rate of <25/min. Expiratory positive airway pressure (EPAP) titrated to maintain SpO2 >90% with Fi = 0.6 and minimise the leak and patient intolerence.

The protocol for NIV patients to be intubated includes worsening respiratory parameters with RR >30/min and pO2 >80 with Fi = 0.6. The development of decreased conciousness, secretions, and hemodynamic or electrocardiographic instability, and refusal for facemask application required intubation.

All patients were monitored with clinical parameters including RR, SpO2, HR, and MAP. The blood gas analysis for oxygenation and ventilation was done prior and 1 hr after application of NIV or intubation followed by daily or as per the need. The radiological improvement is assessed by serial chest X-rays.

For pain control, all patients were given intravenous analgesia with paracetamol injection. The fentanyl patch of 50 mcg/hr was used in all patients, along with 50 mcg top up if required. We used visual analogue scale for assessment of severity of pain.

All the patients were observed for the duration of ventilatory days, complications such as pneumonia and sepsis, length of stay in ICU, and mortality.

The statistical analysis was done using statistical software SPSS for windows (Version 16.0). Chi-square test was used for categorical variables. Student's t test was used for comparing two groups of mean. A P value < 0.05 is considered as statistically significant.

Results

In our study, we enrolled 30 patients, who were admitted to ICU due to blunt chest trauma and randomly assigned to ET and NIV groups of 15 patients in each. One patient in NIV group needed emergency intubation due to worsening of respiratory parameters. None of the patients were excluded from the study. There were no significant differences in age, sex, and weight in between the two groups. The comparison of baseline clinical and physiologic parameters is shown in [Table 2].

Table 2

Comparison of baseline clinical and physiologic parameters

Variable	Group 1 (n=15)	Group 2 (n=15)	P
Age (years)	38.27±7.32	36.93±6.79	0.473
Sex (male/female)	14/1	14/1	1
Weight (kg)	55.93±5.67	57.33±4.82	0.473
HR	121.13±8.41	124.53±10.30	0.331
RR	40.47±5.59	39,87±4,29	0.744
PO2	52.40±5.60	55.20±8.77	0.306
PCO2	49.52±3.50	51.33±5.87	0.313
Ph	7.34±0.045	7.33±0.037	0.408
P/F ratio	233.07±17.27	229.80±22.34	0.658
TTSS at admission	11.87±2.13	11.27±2.37	0.473

We used duration of stay in ICU, complication, and mortality among the two groups as primary outcome. The mean duration of stay in ICU was lesser in NIV group, but it was not statistically significant. Rate of complications was significantly higher in ET group, which include nosocomial infection (nine patients) and ARDS (one patient), compared with NIV group, only three patients developed nosocomial infection (P = 0.010) [Table 3].

Table 3

Primary outcomes

Variable	Group 1 (n=15)	Group 2 (n=15)	P
ICU stay	12.27±4.52	10.13±2.69	0.128
Complication	10 (66.7%)	1 (6.7%)	0.010
Mortality	5 (33.3%)	1 (6.7%)	0.068

HR dropped significantly in ET group within 1 hour of initiation of mechanical ventilation (P < 0.001) [Figure 1]. The respiratory rate, pO2, pCO2 and P/F ratio were improved in both the groups [Figures 2–5]. We observed that the oxygenation was significantly improved in NIV group within 24 hr; later it become equivalent to ET group patients while the pCO2 level was significantly lower in ET group compared to NIV group. Analgesia in both the groups is maintained to keep visual analog scale (VAS) score below 2 and was comparable in both the groups.

Figure 1

Comparison of mean heart rate (per minute) between two groups at different time intervals

Figure 2

Comparison of mean respiratory rate (per minute) between two groups at different time intervals

Figure 5

Comparison of mean P/F ratio between two groups at different time intervals

Comparison of mean pO2 (per mmHg) between two groups at different time intervals

Comparison of mean PCO2 (per mmHg) between two groups at different time intervals

Discussion

The main aim of ventilatory management is to support respiratory system and prevent ventilator-associated lung injury which may progress to ARDS or multiple organ failure syndrome (MOFS). The first modern approach for flail chest was established by Avery et al.[14] They reported that continued mechanical ventilation is required for internal stabilization of chest wall. Antonelli et al.[15] described two techniques for ventilation in hypoxic respiratory failure: invasive and non-invasive. They also found NIV is associated with lesser complication and shorter stay in ICU. In our study, the complication rate and stay in ICU both were higher in ET group.

The advantages of NIV are avoidance of complications of intubation, avoidance of sedation and analgesia, and easy removal and reinstitution. Its effectiveness in hypoxemic respiratory failure for decreasing mortality and intubation rates is demonstrated in the meta-analysis.[16]

There has been a scarcity of randomized controlled trials on ventilatory management of patients with posttraumatic hypoxemic respiratory failure. The British Thoracic Society has issued a low-grade recommendation in its guidelines based on the available level C evidence for the use of NIV in multiple trauma patients.[17] Similarly, no recommendations were proposed by Canadian Critical Care Trials Group/Canadian Critical Care Society Non-invasive Ventilation Guidelines Group.[18]

In a prospective study by Tanaka et al., the use of continuous positive airway pressure (CPAP) in 59 patients with flail chest injury was investigated. They found CPAP group had a lower rate of pulmonary complications and a significantly lower rate of invasive mechanical ventilation use compared to historically treated patients.[19] Gunduz et al. executed a randomized comparison of mask CPAP to intermittent positive pressure ventilation via endotracheal intubation in 52 patients in a treatment study. The results showed that CPAP led to a lower mortality (20% vs 33%, P < 0.01) and nosocomial infection rate (18% vs 48%, P = 0.001). However, a difference in the length of intensive care unit stay could not be demonstrated, and the small number of patients enrolled as well as single-center design raised concerns regarding generalizability.[20]

In our study, BiPAP was efficient in improving gas exchange and symptomatic relief. The mortality was lower in NIV group (7% vs 33%, P = 0.01), and incidence of pneumonia in our study was 60% in ET group versus 20% in NIV. One patient of BiPAP group required intubation (intubation rate of 7%). This agrees with the study by Duggal et al.[21] in 2013, which states that the safety and efficacy of NIV in blunt chest trauma was found at an intubation rate 18%.

Nosocomial pneumonia and pneumothorax were the most common adverse events in NIV use as per previous study by Shebl et al.[22] They found that the incidence of pneumonia was 30% in intubated patients whereas incidence of pneumothorax was 0% and 10% in respective studies. The patients with higher TTSSs had a higher rate of complications, prolonged stay in ICU, and higher mortality.

Conclusion

Based on the findings of our study, both the ventilatory strategies are effective in improving ventilatory parameters. NIV may be considered to be a better option among the two strategies in patients who are neurologically intact and hemodynamically stable. Although it cannot replace intubation in severe respiratory distress, it can prevent mild to moderate respiratory distress. The endotracheal intubation is also associated with serious complications as compared to NIV. The use of NIV in appropriate patients decreases complications, mortality, duration of stay in ICU, resources use, and cost. The limitations of our study were smaller patient population sample and single center study; furthermore, larger trials are needed to find NIV efficacy in flail chest.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.