Diagnosis of pneumothorax in critically ill adults

Unexpected Tension Pneumothorax Developed during Anesthetic Induction Aggravated by Positive Pressure Ventilation: A Case Report

Background and Objectives: Tension pneumothorax is a life-threatening emergency condition that requires immediate diagnosis and intervention. However, due to the non-specific symptoms and the rarity of its occurrence during surgery, anesthesiologists encounter difficulties in promptly diagnosing tension pneumothorax when it arises intraoperatively. Diagnosing tension pneumothorax can become even more challenging in unexpected situations in patients with normal preoperative evaluation for general anesthesia. Materials and Methods, Results: We report the case of a 66-year-old woman who underwent general anesthesia for oblique lateral interbody fusion surgery of her lumbar spine. Though she did not have any respiratory symptoms prior to the induction of anesthesia, auscultation following endotracheal intubation indicated decreased breathing sound in the left hemithorax of the chest. Subsequently, her vital signs showed tachycardia, hypotension, and hypoxemia, and the ventilator indicated a gradual increase in the airway pressure. We verified the proper depth of the endotracheal tube to exclude one-lung ventilation, and, in the meantime, learned that there had been unsuccessful attempts at left subclavian venous catheterization by the surgical department on the previous day. Tension pneumothorax was diagnosed through portable chest radiography in the operating room, and needle thoracostomy and chest tube insertion were performed immediately, which in turn stabilized her vital signs and airway pressure. The surgery was uneventful, and the chest tube was removed one week later after evaluation by the cardiothoracic department. The patient was discharged from hospital on postoperative day 14 without known complications. Conclusions: Anesthesiologists should be aware of the conditions and risk factors that may cause tension pneumothorax and remain vigilant for signs of its development throughout surgery, even for patients who show normal preoperative assessments. An undetected small pneumothorax without any symptoms can progress to tension pneumothorax through positive pressure ventilation during general anesthesia, posing a life-threatening situation. If a tension pneumothorax is highly suspected through clinical assessments, its prompt differentiation and timely diagnosis are crucial, allowing for rapid intervention to stabilize vital signs.

Critical Damage of Lung Parenchyma Complicated with Massive Pneumothorax in COVID-19 Pneumonia

It is already known that Coronavirus disease 2019 (COVID-19) may lead to various degrees and forms of lung parenchyma damage, but some cases take a strikingly severe course that is difficult to manage. We report the case of a 62-year old male, non-obese, non-smoker, and non-diabetic, who presented with fever, chills, and shortness of breath. The infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was diagnosed by real-time Polymerase Chain Reaction. Although the patient had been vaccinated with 2 doses of Pfizer-BioNTech COVID-19 vaccine 7 months earlier and had no risk factors for a severe outcome, serial computed tomography (CT) scan revealed lung involvement progressively extending from an initial 30% to 40% to almost 100% 2.5 months later. The spectrum of lung lesions included at first only ground-glass opacities and some tiny emphysema bullae, but later also bronchiectasis, pulmonary fibrosis, and large emphysema bullae as post-COVID-19 pulmonary sequelae. For fear of severe evolution of superimposed bacterial infection (Clostridoides difficile enterocolits and possibly bacterial pneumonia) the administration of corticosteroids was intermittent. Massive right pneumothorax secondary to bulla rupture, possibly favored by the indispensable high flow oxygen therapy, led to respiratory failure compounded by hemodynamic instability, and ultimately to the patient's final demise. COVID-19 pneumonia may cause severe lung parenchyma damage which requires long-term supplemental oxygen therapy. Beneficial or even lifesaving as it might be, high flow oxygen therapy may nonetheless have deleterious effects too, including the development of bullae that may rupture engendering pneumothorax. Corticosteroid treatment should probably be pursued despite superimposed bacterial infection to limit the viral induced damage to lung parenchyma.

Management of complex pleural disease in the critically ill patient

Disorders of the pleural space are quite common in the critically ill patient. They are generally associated with the underlying illness. It is sometimes difficult to assess for pleural space disorders in the ICU given the instability of some patients. Although the portable chest X-ray remains the primary modality of diagnosis for pleural disorders in the ICU. It can be nonspecific and may miss subtle findings. Ultrasound has become a useful tool to the bedside clinician to aid in diagnosis and management of pleural disease. The majority of pleural space disorders resolve as the patient’s illness improves. There remain a few pleural processes that need specific therapies. While uncomplicated parapneumonic effusions do not have their own treatments. Those that progress to become a complex infected pleural space can have its individual complexity in therapy. Chest tube drainage remains the cornerstone in therapy. The use of intrapleural fibrinolytics has decreased the need for surgical referral. A large hemothorax or pneumothorax in patients admitted to the ICU represent medical emergencies and require emergent action. In this review we focus on the management of commonly encountered complex pleural space disorders in critically ill patients such as complicated pleural space infections, hemothoraces and pneumothoraces.

Pneumothorax in patients with respiratory failure in ICU

Pneumothorax is not an uncommon occurrence in ICU patients. Barotrauma and iatrogenesis remain the most common causes for pneumothorax in critically ill patients. Patients with underlying lung disease are more prone to develop pneumothorax, especially if they require positive pressure ventilation. A timely diagnosis of pneumothorax is critical as it may evolve into tension physiology. Most occurrences of pneumothoraces are readily diagnosed with a chest X-ray. Tension pneumothorax is a medical emergency, and managed with immediate needle decompression followed by tube thoracostomy. A computed tomography (CT) scan of the chest remains the gold standard for diagnosis; however, getting a CT scan of the chest in a critically ill patient can be challenging. The use of thoracic ultrasound has been emerging and is proven to be superior to chest X-ray in making a diagnosis. The possibility of occult pneumothorax in patients with thoracoabdominal blunt trauma should be kept in mind. Patients with pneumothorax in the ICU should be managed with a tube thoracostomy if they are symptomatic or on mechanical ventilation. The current guidelines recommend a small-bore chest tube as the first line management of pneumothorax. In patients with persistent air leak or whose lungs do not re-expand, a thoracic surgery consultation is recommended. In non-surgical candidates, bronchoscopic interventions or autologous blood patch are other options.

Thoracic abnormal air collections in patients in the intensive care unit: radiograph findings correlated with CT

An abnormal collection of air in the thorax is one of the most common life-threatening events that occurs in the intensive care unit. Patient management differs depending on the location of the air collection; therefore, detecting abnormal air collection and identifying its exact location on supine chest radiographs is essential for early treatment and positive patient outcomes. Thoracic abnormal air collects in multiple thoracic spaces, including the pleural cavity, chest wall, mediastinum, pericardium, and lung. Pneumothorax in the supine position shows different radiographic findings depending on the location. Many conditions, such as skin folds, interlobar fissure, bullae in the apices, and air collection in the intrathoracic extrapleural space, mimic pneumothorax on radiographs. Additionally, pneumopericardium may resemble pneumomediastinum and needs to be differentiated. Further, some conditions such as inferior pulmonary ligament air collection versus a pneumatocele or pneumothorax in the posteromedial space require a differential diagnosis based on radiographs. Computed tomography (CT) is required to localize the air and delineate potential etiologies when a diagnosis by radiography is difficult. The purposes of this article are to review the anatomy of the potential spaces in the chest where abnormal air can collect, explain characteristic radiographic findings of the abnormal air collection in supine patients with illustrations and correlated CT images, and describe the distinguishing features of conditions that require a differential diagnosis. Since management differs based on the location of the air collection, radiologists should try to accurately detect and identify the location of air collection on supine radiographs.

Depiction of pneumothoraces in a large animal model using x-ray dark-field radiography

The aim of this study was to assess the diagnostic value of x-ray dark-field radiography to detect pneumothoraces in a pig model. Eight pigs were imaged with an experimental grating-based large-animal dark-field scanner before and after induction of a unilateral pneumothorax. Image contrast-to-noise ratios between lung tissue and the air-filled pleural cavity were quantified for transmission and dark-field radiograms. The projected area in the object plane of the inflated lung was measured in dark-field images to quantify the collapse of lung parenchyma due to a pneumothorax. Means and standard deviations for lung sizes and signal intensities from dark-field and transmission images were tested for statistical significance using Student's two-tailed t-test for paired samples. The contrast-to-noise ratio between the air-filled pleural space of lateral pneumothoraces and lung tissue was significantly higher in the dark-field (3.65 ± 0.9) than in the transmission images (1.13 ± 1.1; p = 0.002). In case of dorsally located pneumothoraces, a significant decrease (-20.5%; p > 0.0001) in the projected area of inflated lung parenchyma was found after a pneumothorax was induced. Therefore, the detection of pneumothoraces in x-ray dark-field radiography was facilitated compared to transmission imaging in a large animal model.

Facilitated Diagnosis of Pneumothoraces in Newborn Mice Using X-ray Dark-Field Radiography

OBJECTIVE

The aim of this study was to evaluate the diagnostic value of x-ray dark-field imaging in projection radiography-based depiction of pneumothoraces in the neonatal murine lung, a potentially life-threatening medical condition that requires a timely and correct diagnosis.

MATERIALS AND METHODS

By the use of a unique preclinical model, 7-day-old C57Bl/6N mice received mechanical ventilation for 2 or 8 hours with oxygen-rich gas (FIO2 = 0.4; n = 24). Unventilated mice either spontaneously breathed oxygen-rich gas (FIO2 = 0.4) for 2 or 8 hours or room air (n = 22). At the end of the experiment, lungs were inflated with a standardized volume of air after a lethal dose of pentobarbital was administered to the pups. All lungs were imaged with a prototype grating-based small-animal scanner to acquire x-ray transmission and dark-field radiographs. Image contrast between the air-filled pleural space and lung tissue was quantified for both transmission and dark-field radiograms. After the independent expert's assessment, 2 blinded readers evaluated all dark-field and transmission images for the presence or absence of pneumothoraces. Contrast ratios, diagnostic accuracy, as well as reader's confidence and interreader agreement were recorded for both imaging modalities.

RESULTS

Evaluation of both x-ray transmission and dark-field radiographs by independent experts revealed the development of a total of 10 pneumothoraces in 8 mice. Here, the contrast ratio between the air-filled pleural space of the pneumothoraces and the lung tissue was significantly higher in the dark field (8.4 ± 3.5) when compared with the transmission images (5.1 ± 2.8; P < 0.05). Accordingly, the readers' diagnostic confidence for the diagnosis of pneumothoraces was significantly higher for dark-field compared with transmission images (P = 0.001). Interreader agreement improved from moderate for the analysis of transmission images alone (κ = 0.41) to very good when analyzing dark-field images alone (κ = 0.90) or in combination with transmission images (κ = 0.88). Diagnostic accuracy significantly improved for the analysis of dark-field images alone (P = 0.04) or in combination with transmission images (P = 0.02), compared with the analysis of transmission radiographs only.

CONCLUSIONS

The significant improvement in contrast ratios between lung parenchyma and free air in the dark-field images allows the facilitated detection of pneumothoraces in the newborn mouse. These preclinical experiments indicate the potential of the technique for future clinical applications.

Conventional vs invert-grayscale X-ray for diagnosis of pneumothorax in the emergency setting

INTRODUCTION

Pneumothorax is a pathologic condition in which air is accumulated between the visceral and parietal pleura. After clinical suspicion, in order to diagnose the severity of the condition, imaging is necessary. By using the help of Picture Archiving and Communication Systems (PACS) direct conventional X-rays are converted to gray-scale and this has become a preferred method among many physicians.

METHODS

Our study design was a case-control study with cross-over design study. Posterior-anterior chest X-rays of patients were evaluated for pneumothorax by 10 expert physicians with at least 3years of experience and who have used inverted gray-scale posterior anterior chest X-ray for diagnosing pneumothorax.

RESULTS

The study included posterior anterior chest X-ray images of 268 patients of which 106 were diagnosed with spontaneous pneumothorax and 162 patients used as a control group. The sensitivity of Digital-conventional X-rays was found to be higher than that of inverted gray-scale images (95% CI (2,08-5,04), p<0,01). There was no statistically significant difference between the gold standard and digital-conventional images (95% CI (0,45-2,17), p=0,20), while the evaluations of the gray-scale images were found to be less sensitive for diagnosis (95% CI (3,16-5,67) p<0,01).

CONCLUSION

Inverted gray-scale imaging is not a superior imaging modality over digital-conventional X-ray for the diagnosis of pneumothorax. Prospective studies should be performed where diagnostic potency of inverted gray-scale radiograms is tested against gold standard chest CT. Further research should compare inverted grayscale to lung ultrasound to assess them as alternatives prior to CT.

Ultrasound-Guided Placement of Central Venous Port Systems via the Right Internal Jugular Vein: Are Chest X-Ray and/or Fluoroscopy Needed to Confirm the Correct Placement of the Device?

BACKGROUND

Percutaneous central venous port (CVP) placement using ultrasound-guidance (USG) via right internal jugular vein is described as a safe and effective procedure. The aim of this study is to determine whether intraoperative fluoroscopy (IF) and/or postoperative chest X-ray (CXR) are required to confirm the correct position of the catheter.

METHODS

Between January 2012 and December 2014, 302 adult patients underwent elective CVP system placement under USG. The standard venous access site was the right internal jugular vein. The length of catheter was calculated based on the height of the patient. IF was always performed to confirm US findings.

RESULTS

176 patients were men and 126 were women and average height was 176.2 cm (range 154-193 cm). The average length of the catheter was 16.4 cm (range 14-18). Catheter malposition and pneumothorax were observed in 4 (1.3 %) and 3 (1 %) patients, respectively. IF confirmed the correct position of the catheter in all cases. Catheter misplacement (4 cases) was previously identified and corrected on USG. Our rates of pneumothorax are in accordance with those of the literature (0.5-3 %).

CONCLUSION

Ultrasonography has resulted in improved safety and effectiveness of port system implantation. The routine use of CXR and IF should be considered unnecessary.

Prevalence and risk factors of pneumothorax among patients admitted to a Pediatric Intensive Care Unit

OBJECTIVE

Pneumothorax should be considered a medical emergency and requires a high index of suspicion and prompt recognition and intervention.

AIMS

The objective of the study was to evaluate cases developing pneumothorax following admission to a Pediatric Intensive Care Unit (PICU) over a 5-year period.

SETTINGS AND DESIGN

Case notes of all PICU patients (n = 1298) were reviewed, revealing that 135 cases (10.4%) developed pneumothorax, and these were compared with those patients who did not. The most common tool for diagnosis used was chest X-ray followed by a clinical examination.

SUBJECTS AND METHODS

Case notes of 1298 patients admitted in PICU over 1-year study.

RESULTS

Patients with pneumothorax had higher mortality rate (P < 0.001), longer length of stay (P < 0.001), higher need for mechanical ventilation (MV) (P < 0.001), and were of younger age (P < 0.001), lower body weight (P < 0.001), higher pediatric index of mortality 2 score on admission (P < 0.001), higher pediatric logistic organ dysfunction score (P < 0.001), compared to their counterpart. Iatrogenic pneumothorax (IP) represented 95% of episodes of pneumothorax. The most common causes of IP were barotrauma secondary to MV, central vein catheter insertion, and other (69.6%, 13.2%, and 17.2%, respectively). Compared to ventilated patients without pneumothorax, ventilated patients who developed pneumothorax had a longer duration of MV care (P < 0.001) and higher nonconventional and high-frequency oscillatory ventilation settings (P < 0.001).

CONCLUSIONS

This study demonstrated that pneumothorax is common in Alexandria University PICU patients, especially in those on MV and emphasized the importance of the strict application of protective lung strategies among ventilated patients to minimize the risk of pneumothorax.

Pneumothorax Related to Mechanical Ventilation: Silent Enemy

Pneumothorax is well known and described complication in intensive care unit patients (ICU). Incidence of this complication is higher in patients with underlying pathology. As it can be occult, it is of the most importance to think of it in patients on mechanical ventilation. In this case report we well present ventilator-related pneumothorax in infant: clinical presentation, diagnosis and management

Emergency central venous catheterization during trauma resuscitation: a safety analysis by site

Central venous catheterization (CVC) is often necessary during initial trauma resuscitations, but may cause complications including catheter-related blood stream infection (CRBSI), deep venous thrombosis (DVT), pulmonary emboli (PE), arterial injury, or pneumothoraces. Our primary objective compared subclavian versus femoral CVC complications during initial trauma resuscitations. A retrospective review (2010-2011) at an urban, Level-I Trauma Center reviewed CVCs during initial trauma resuscitations. Demographics, clinical characteristics, and complications including: CRBSIs, DVTs, arterial injuries, pneumothoraces, and PEs were analyzed. Fisher's exact test and Student's t test were used; P ≤ 0.05 was considered statistically significant. Overall, 504 CVCs were placed (subclavian, n = 259; femoral, n = 245). No difference in age (47 ± 22 vs 45 ± 23 years) or body mass index (28 ± 6 vs 29 ± 16 kg/m(2)) was detected (P > 0.05) in subclavian vs femoral CVC, but subclavian CVCs had more blunt injuries (81% vs 69%), greater systolic blood pressure (95 ± 55 vs 83 ± 43 mmHg), greater Glasgow Coma Scale (10 ± 5 vs 9 ± 5), and less introducers (49% vs 73%) than femoral CVCs (all P < 0.05). Catheter related arterial injuries, PEs, and CRBSIs were similar in subclavian and femoral groups (3% vs 2%, 0% vs 1%, and 3% vs 3%; all P > 0.05). Catheter-related DVTs occurred in 2 per cent of subclavian and 9 per cent of femoral CVCs (P < 0.001). There was a 3 per cent occurrence of pneumothorax in the subclavian CVC population. In conclusion, both subclavian and femoral CVCs caused significant complications. Subclavian catheter-related pneumothoraces occurred more commonly and femoral CRBSIs less commonly than expected compared with prior literature in nonemergent scenarios. This suggests that femoral CVC may be safer than subclavian CVC during initial trauma resuscitations.

Emergency sonography AIDS diagnostic accuracy of torso injuries: a study in a resource limited setting

Introduction. Clinical evaluation of patients with torso trauma is often a diagnostic challenge. Extended focused assessment with sonography for trauma (EFAST) is an emergency ultrasound scan that adds to the evaluation of intrathoracic abdominal and pericardial cavities done in FAST (focused assessment with sonography for trauma). Objective. This study compares EFAST (the index test) with the routine standard of care (SoC) investigations (the standard reference test) for torso trauma injuries. Methods. A cross-sectional descriptive study was conducted over a 3-month period. Eligible patients underwent EFAST scanning and the SoC assessment. The diagnostic accuracy of EFAST was calculated using sensitivity and specificity scores. Results. We recruited 197 patients; the M : F ratio was 5 : 1, with mean age of 27 years (SD 11). The sensitivity of EFAST was 100%, the specificity was 97%, the PPV was 87%, and the NPV was 100%. It took 5 minutes on average to complete an EFAST scan. 168 (85%) patients were EFAST-scanned. Most patients (82) (48%) were discharged on the same day of hospitalization, while 7 (4%) were still at the hospital after two weeks. The mortality rate was 18 (9%). Conclusion. EFAST is a reliable method of diagnosing torso injuries in a resource limited context.

Iatrogenic pneumothorax related to mechanical ventilation

Pneumothorax is a potentially lethal complication associated with mechanical ventilation. Most of the patients with pneumothorax from mechanical ventilation have underlying lung diseases; pneumothorax is rare in intubated patients with normal lungs. Tension pneumothorax is more common in ventilated patients with prompt recognition and treatment of pneumothorax being important to minimize morbidity and mortality. Underlying lung diseases are associated with ventilator-related pneumothorax with pneumothoraces occurring most commonly during the early phase of mechanical ventilation. The diagnosis of pneumothorax in critical illness is established from the patients’ history, physical examination and radiological investigation, although the appearances of a pneumothorax on a supine radiograph may be different from the classic appearance on an erect radiograph. For this reason, ultrasonography is beneficial for excluding the diagnosis of pneumothorax. Respiration-dependent movement of the visceral pleura and lung surface with respect to the parietal pleura and chest wall can be easily visualized with transthoracic sonography given that the presence of air in the pleural space prevents sonographic visualization of visceral pleura movements. Mechanically ventilated patients with a pneumothorax require tube thoracostomy placement because of the high risk of tension pneumothorax. Small-bore catheters are now preferred in the majority of ventilated patients. Furthermore, if there are clinical signs of a tension pneumothorax, emergency needle decompression followed by tube thoracostomy is widely advocated. Patients with pneumothorax related to mechanical ventilation who have tension pneumothorax, a higher acute physiology and chronic health evaluation II score or PaO₂/FiO₂ < 200 mmHg were found to have higher mortality.

Pneumothorax in the critically ill patient

Pneumothorax in critically ill patients remains a common problem in the ICU, occurring in 4% to 15% of patients. Pneumothorax should be considered a medical emergency and requires a high index of suspicion, prompt recognition, and intervention. The diagnosis of pneumothorax in the critically ill patient can be made by physical examination findings or radiographic studies including chest radiographs, ultrasonography, or CT scanning. Ultrasonography is emerging as the diagnostic procedure of choice for the diagnosis and management guidance and management of pneumothoraces, if expertise is available. Pneumothoraces in unstable, critically ill patients or in those on mechanical ventilation should be managed with tube thoracostomy. If there is suspicion for tension pneumothorax, immediate decompression and drainage should be performed. With widespread use of CT scanning, there have been more occult pneumothoraces diagnosed, and the most recent literature suggests that drainage is preferred. In patients with a persistent air leak or failure of the lung to expand, current guidelines suggest that an early thoracic surgical consultation be requested within 3 to 5 days.

Diagnosis of pneumothorax by radiography and ultrasonography: a meta-analysis

OBJECTIVE

This study compares, by meta-analysis, the use of anterior-posterior chest radiography (CR) with transthoracic ultrasonography for the diagnosis of pneumothorax.

METHODS

English-language articles on the performance of CR and ultrasonography in the diagnosis of a pneumothorax were selected. In eligible studies, data were recalculated, and the forest plots and summary receiver operating characteristic (sROC) curves were analyzed.

RESULTS

Pooled sensitivity and specificity were 0.88 and 0.99, respectively, for ultrasonography, and 0.52 and 1.00, respectively, for CR. For ultrasonography performed by clinicians other than radiologists, pooled sensitivity and specificity were 0.89 and 0.99, respectively. The sROC areas under the curve were compared, and no significant differences between ultrasonography and CR were found. Meta-regression analysis implied that the operator is strongly associated with accuracy (relative diagnostic OR, 0.21; 95% CI, 0.05-0.96; P = .0455).

CONCLUSIONS

The meta-analysis indicated that bedside ultrasonography performed by clinicians had higher sensitivity and similar specificity compared with CR in the diagnosis of pneumothorax, but the accuracy of ultrasonography in the diagnosis of pneumothorax depended on the skill of the operators.

Routine chest X-ray is not required after a low-risk central venous cannulation

BACKGROUND

Knowledge of the radiographic catheter tip position after central venous cannulation is normally not required for short-term catheter use. Detection of a possible iatrogenic pneumothorax may nevertheless justify routine post-procedure chest X-ray. Our aim was to design a clinical decision rule to select patients for radiographic evaluation after central venous cannulation.

METHODS

A total of 2230 catheterizations performed using external jugular, internal jugular or subclavian venous approaches during a 4-year period were included consecutively. Information on patient data and corresponding procedures was recorded prospectively. A post-procedure chest X-ray was obtained after each cannulation.

RESULTS

Thirteen cases (0.58%) of cannulation-associated pneumothorax were identified. The risk of pneumothorax after a technically difficult (1.8%) or subclavian (1.6%) cannulation was significantly higher than after cannulation not considered as difficult (0.37%) or performed using other routes (0.33%). Clinical signs of pneumothorax within 8 h of cannulation were found in all seven patients with pneumothorax requiring specific treatment. A new clinical decision rule for radiographic evaluation after central venous cannulation based on the results of the present study shows that 48% of the post-procedure chest X-rays performed in our patients were clinically redundant.

CONCLUSION

Clinical symptoms were reported in all patients with pneumothorax requiring specific treatment. Approximately half of the post-procedure chest X-ray controls could be avoided using the proposed clinical decision rule to select patients for radiographic evaluation after central venous cannulation. A large prospective multi-centre study should be carried out to further evaluate this decision rule.

Real-time detection of pneumothorax using electrical impedance tomography

OBJECTIVES

Pneumothorax is a frequent complication during mechanical ventilation. Electrical impedance tomography (EIT) is a noninvasive tool that allows real-time imaging of regional ventilation. The purpose of this study was to 1) identify characteristic changes in the EIT signals associated with pneumothoraces; 2) develop and fine-tune an algorithm for their automatic detection; and 3) prospectively evaluate this algorithm for its sensitivity and specificity in detecting pneumothoraces in real time.

DESIGN

Prospective controlled laboratory animal investigation.

SETTING

Experimental Pulmonology Laboratory of the University of São Paulo.

SUBJECTS

Thirty-nine anesthetized mechanically ventilated supine pigs (31.0 +/- 3.2 kg, mean +/- SD).

INTERVENTIONS

In a first group of 18 animals monitored by EIT, we either injected progressive amounts of air (from 20 to 500 mL) through chest tubes or applied large positive end-expiratory pressure (PEEP) increments to simulate extreme lung overdistension. This first data set was used to calibrate an EIT-based pneumothorax detection algorithm. Subsequently, we evaluated the real-time performance of the detection algorithm in 21 additional animals (with normal or preinjured lungs), submitted to multiple ventilatory interventions or traumatic punctures of the lung.

MEASUREMENTS AND MAIN RESULTS

Primary EIT relative images were acquired online (50 images/sec) and processed according to a few imaging-analysis routines running automatically and in parallel. Pneumothoraces as small as 20 mL could be detected with a sensitivity of 100% and specificity 95% and could be easily distinguished from parenchymal overdistension induced by PEEP or recruiting maneuvers. Their location was correctly identified in all cases, with a total delay of only three respiratory cycles.

CONCLUSIONS

We created an EIT-based algorithm capable of detecting early signs of pneumothoraces in high-risk situations, which also identifies its location. It requires that the pneumothorax occurs or enlarges at least minimally during the monitoring period. Such detection was operator-free and in quasi real-time, opening opportunities for improving patient safety during mechanical ventilation.

Rapid detection of pneumothorax by ultrasonography in patients with multiple trauma

Introduction

Early detection of pneumothorax in multiple trauma patients is critically important. It can be argued that the efficacy of ultrasonography (US) for detection of pneumothorax is enhanced if it is performed and interpreted directly by the clinician in charge of the patients. The aim of this study was to assess the ability of emergency department clinicians to perform bedside US to detect and assess the size of the pneumothorax in patients with multiple trauma.

Methods

Over a 14 month period, patients with multiple trauma treated in the emergency department were enrolled in this prospective study. Bedside US was performed by emergency department clinicians in charge of the patients. Portable supine chest radiography (CXR) and computed tomography (CT) were obtained within an interval of three hours. Using CT and chest drain as the gold standard, the diagnostic efficacy of US and CXR for the detection of pneumothorax, defined as rapidity and accuracy (sensitivity, specificity, positive predictive value, negative predictive value), were compared. The size of the pneumothorax (small, medium and large) determined by US was also compared to that determined by CT.

Results

Of 135 patients (injury severity score = 29.1 ± 12.4) included in the study, 83 received mechanical ventilation. The time needed for diagnosis of pneumothorax was significantly shorter with US compared to CXR (2.3 ± 2.9 versus 19.9 ± 10.3 minutes, p < 0.001). CT and chest drain confirmed 29 cases of pneumothorax (21.5%). The diagnostic sensitivity, specificity, positive and negative predictive values and accuracy for US and radiography were 86.2% versus 27.6% (p < 0.001), 97.2% versus 100% (not significant), 89.3% versus 100% (not significant), 96.3% versus 83.5% (p = 0.002), and 94.8% versus 84.4% (p = 0.005), respectively. US was highly consistent with CT in determining the size of pneumothorax (Kappa = 0.669, p < 0.001).

Conclusion

Bedside clinician-performed US provides a reliable tool and has the advantages of being simple and rapid and having higher sensitivity and accuracy compared to chest radiography for the detection of pneumothorax in patients with multiple trauma.

Assessment of the Mechanically Ventilated Patient

Multiple perspectives must be considered when assessing the mechanically ventilated patient. Assessment begins before the advance practice nurse (APN) encounters the patient. Important information about the patient can be gleaned from the history, medications, and social history. The APN then observes the patient to determine if patient-ventilator synchrony has been achieved. Physical findings are gathered and correlated with the chest radiogram. Data from the ventilator are evaluated to assess compliance, minute ventilation, tidal volume, and other parameters that will assist in the evaluation of the patient's needs. Electrolytes, acid-base state, and nutrition must all be considered to obtain a complete assessment of these patients. From all these data points, the APN can develop a detailed plan of care that will enhance positive patient outcomes.

Pulmonary trauma emergency department evaluation and management

Pulmonary trauma is a significant cause of morbidity and mortality in the United States. It is imperative for the emergency physician to identify promptly patients who require immediate therapy. In patients who have limited injuries, literature shows that often conservative management provides improved outcome. As the exposure to automobiles and firearms continues to increase in the setting of improved prehospital management, the emergency physician will encounter an increasing amount of pulmonary trauma. This rise in respiratory injuries will require a more aggressive approach of patients with minimal morbidity and mortality. A systematic approach to respiratory injuries is crucial to improving patient outcomes.