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Thoracic Surgery > Trauma
Pneumothorax
Article Last Updated: Aug 17, 2006
AUTHOR AND EDITOR INFORMATION
Section 1 of 11  
Author: Rebecca Bascom, MD, MPH, Professor of Medicine, Pennsylvania State College of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, Milton S Hershey Medical Center
Rebecca Bascom is a member of the following medical societies: American Academy of Allergy Asthma and Immunology, American College of Physicians, American Industrial Hygiene Association, American Public Health Association, and American Thoracic Society
Coauthor(s):
Shoaib Alam, MD, Assistant Professor of Medicine, Division of Pulmonary, Allergy and Critical Care, Penn State University and Hershey Medical Center;
Seema Jain, BA, Pennsylvania State University College of Medicine;
Milos Tucakovic, MD, Fellow, Department of Internal Medicine, Sections of Pulmonary Disease, Allergy and Critical Care Medicine, Milton S Hershey Medical Center, Pennsylvania State College of Medicine;
Tunc Iyriboz, MD, Chief, Division of Clinical Image Management, Assistant Professor, Department of Radiology, Hershey Medical Center, Pennsylvania State University
Editors: Benson B Roe, MD, Emeritus Chief, Division of Cardiothoracic Surgery, Emeritus Professor, Department of Surgery, University of California at San Francisco Medical Center; Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine; Daniel S Schwartz, MD, FACS, Clinical Assistant Professor of Cardiothoracic Surgery, New York University School of Medicine; Consulting Staff, Department of Surgery, Division of Thoracic Surgery, North Shore University Hospital/Long Island Jewish Medical Center; Timothy D Rice, MD, Associate Professor, Departments of Internal Medicine and Pediatrics and Adolescent Medicine, Saint Louis University School of Medicine; Mary C Mancini, MD, PhD, Director of Cardiothoracic Transplantation, Professor, Department of Surgery, Louisiana State University Health Sciences Center
Author and Editor Disclosure
Synonyms and related keywords:
pneumothoraces, parenchymal lung disease, apical pleural blebs, chronic obstructive pulmonary disease, COPD, Pneumocystis carinii pneumonia, PCP, hemopneumothorax, bronchopleural fistula, transthoracic needle aspiration, therapeutic thoracentesis, pleural biopsy, central venous catheter insertion, transbronchial biopsy, positive pressure mechanical ventilation, inadvertent intubation of the right mainstem bronchus
Background
Pneumothorax is defined as the presence of air or gas in the pleural cavity. Primary spontaneous pneumothoraces (PSPs) occur in people without underlying lung disease or trauma to the thorax. Many patients whose condition is labeled as primary spontaneous pneumothorax have an unrecognized lung disease. Secondary spontaneous pneumothoraces occur in people with underlying parenchymal lung disease. Traumatic pneumothoraces result from injury, often secondary to medical intervention (ie, iatrogenic pneumothorax). When air is trapped in the pleural cavity, resulting in positive pressure, a tension pneumothorax develops.
Pathophysiology
Primary spontaneous pneumothoraces result from apical pleural blebs lying under the visceral pleura. Primary spontaneous pneumothoraces are typically observed in tall young people without parenchymal lung disease because of increased shear forces in the apex. While patients do not have overt parenchymal disease, they commonly are smokers. More than 90% of patients with primary spontaneous pneumothorax are smokers. The relative risk of primary spontaneous pneumothorax increases as the number of cigarettes smoked per day increases. This incremental risk with increasing number of cigarettes smoked per day is much more pronounced in female smokers. Eighty percent of patients have emphysemalike changes on CT scan, particularly in upper long zones.
The body of evidence that genetic factors may be important in the pathogenesis of many cases of primary spontaneous pneumothorax is growing. Familial clustering of this condition has been reported. Several genetic disorders have been linked to primary spontaneous pneumothorax. Marfan syndrome, homocystinuria, and Birt-Hogg-Dube syndrome are among such disorders. Birt-Hogg-Dube syndrome is an autosomal dominant disorder that is characterized by benign skin tumors (hair follicle hamartomas), renal and colon cancer, and spontaneous pneumothorax. The spontaneous pneumothorax occurs in about 22% of patients with this syndrome. The gene responsible for this syndrome has been identified and is located on chromosome 17. Genetic testing is now available for Birt-Hogg-Dube syndrome.
Secondary spontaneous pneumothoraces (SSP) occur in the presence of lung disease, primarily in the presence of chronic obstructive pulmonary disease (COPD). Other diseases that may be present when secondary spontaneous pneumothoraces occur include tuberculosis, sarcoidosis, cystic fibrosis, malignancy, and idiopathic pulmonary fibrosis.
Pneumocystis jiroveci pneumonia (previously known as Pneumocystis carinii pneumonia [PCP]) was a common cause of secondary spontaneous pneumothorax in patients with AIDS during the last decade. With the advent of highly active antiretroviral therapy (HAART) and widespread use of trimethoprim-sulfamethoxazole prophylaxis, the incidence of PCP and associated SSP has significantly declined. This disease is now primarily seen in patients who are noncompliant with HIV therapy or trimethoprim-sulfamethoxazole prophylaxis or those taking inhaled pentamidine for PCP prophylaxis. PCP in other immunocompromised patients is seen only when trimethoprim-sulfamethoxazole prophylaxis is withdrawn prematurely. For practical purposes, if the immunocompromised patient has been taking trimethoprim-sulfamethoxazole prophylaxis reliably, PCP is reasonably excluded from the differential diagnoses.
Traumatic pneumothoraces can result from both penetrating and nonpenetrating lung injuries. Complications include hemopneumothorax and bronchopleural fistula. Traumatic pneumothoraces can create a 1-way valve in the pleural space, only letting in air without escape, and can lead to a tension pneumothorax.
Iatrogenic pneumothorax is a complication of medical or surgical procedures. It most commonly results from transthoracic needle aspiration. Other procedures commonly causing iatrogenic pneumothorax are therapeutic thoracentesis, pleural biopsy, central venous catheter insertion, transbronchial biopsy, positive pressure mechanical ventilation, and inadvertent intubation of the right mainstem bronchus. Therapeutic thoracentesis is complicated by pneumothorax 30% of the time when performed by inexperienced operators in contrast to only 4% of the time when performed by experienced clinicians. The routine use of ultrasonography during diagnostic thoracentesis is associated with lower rates of pneumothorax (4.9% vs 10.3%) and need for tube thoracostomy (0.7% vs 4.1%). Similarly, in patients who are mechanically ventilated, thoracentesis guided by bedside ultrasonography without radiology support results in a relatively lower rate of pneumothorax.
Tension pneumothorax typically occurs in the intensive care setting in patients who are ventilated. With air trapping in the pleural space, positive pressure rises. This pressure compresses the mediastinum, decreasing venous return to the heart and reducing cardiac output. In addition, owing to ipsilateral lung collapse and contralateral lung compression, gas exchange is compromised, leading to hypoxemia.
Frequency
United States
For men, age-adjusted incidence of primary spontaneous pneumothorax is 7.4 cases per 100,000 persons per year. For women, age-adjusted incidence is 1.2 cases per 100,000 persons per year.
For men, age-adjusted incidence of secondary spontaneous pneumothorax is 6.3 cases per 100,000 persons per year; for women, age-adjusted incidence is 2.0 cases per 100,000 persons per year. In patients with COPD, incidence is 26 cases per 100,000 patients per year.
Traumatic pneumothoraces occur more frequently than spontaneous pneumothoraces, and the rate is increasing.
Mortality/Morbidity
Recurrences usually strike within the first 6 months to 3 years. The overall recurrence rate is about 28% for primary spontaneous pneumothorax and 43% for secondary spontaneous pneumothorax over a period of 5 years.
- Recurrences are more common among patients who smoke, patients with COPD, and patients with AIDS. Predictors of recurrence include pulmonary fibrosis, younger age, and increased height-to-weight ratio. Evidence of bullous lesions on CT scan or thoracoscopy is not predictive of recurrence.In a retrospective study of 182 consecutive patients of newly diagnosed first episode of pneumothorax, a higher rate of recurrence was noted in taller patients, thin patients and patients with SSP. Patients who underwent pleurodesis had cumulative rates of recurrence 13%, 16% and 27% at 6 months, one year and 3-years, respectively, compared to 26%, 33% and 50% respectively in patients treated with chest tube drainage. The use of tetracycline or gentamicin did not have any significant impact on the recurrence rate.
- Complications include hypoxemic respiratory failure, respiratory or cardiac arrest, hemopneumothorax, and bronchopulmonary fistula.
- Complications include hypoxemic respiratory failure, respiratory or cardiac arrest, hemopneumothorax, and bronchopulmonary fistula.
- Primary spontaneous pneumothorax is typically benign and often resolves without medical attention.
- While the risk of mortality with primary spontaneous pneumothoraces is low, a higher risk of mortality with secondary spontaneous pneumothoraces exists. In particular, patients with COPD are at great risk, with a 3.5-fold increase in relative mortality.
- Studies indicate a mortality rate of 1-17% in patients with COPD and a secondary spontaneous pneumothorax. One study indicated that 5% of patients with COPD died before a chest tube was placed.
- Patients with AIDS also have a high inpatient mortality rate of 25% and a median survival of 3 months after the pneumothorax.
Sex
For primary spontaneous pneumothorax, the male-to-female ratio of age-adjusted rates is 6.2:1. For a secondary spontaneous pneumothorax, the male-to-female ratio of age-adjusted rates is 3.2:1.
Age
- Primary spontaneous pneumothoraces occur in people aged 20-30 years. Peak incidence is in the early twenties, and it is rarely observed in people older than 40 years.
- Secondary spontaneous pneumothoraces occur more frequently in patients aged 60-65 years.
History
Most episodes of spontaneous pneumothorax occur at rest. Spontaneous pneumothorax is not associated with trauma or stress.
- Acute onset of chest pain and shortness of breath were present in all the patients in one series. Typically, both symptoms are present in 64% of patients.
- Acute onset of chest pain - Severe and/or stabbing pain, radiating to ipsilateral shoulder and increasing with inspiration (pleuritic)
- Sudden shortness of breath
- Anxiety, cough, and vague presenting symptoms (eg, general malaise, fatigue) are less commonly observed.
- Dyspnea tends to be more severe with secondary spontaneous pneumothoraces because of decreased lung reserve.
Physical
- General appearance
- Diaphoretic
- Splinting chest wall to relieve pleuritic pain
- Cyanotic (with tension pneumothoraces)
- Vital signs
- Tachypnea
- Tachycardia (most common finding) - If faster than 135 beats per minute (bpm), tension pneumothorax is likely.
- Pulsus paradoxus
- Hypotension (often with tension pneumothorax)
- Asymmetric lung expansion - Mediastinal and tracheal shift to the contralateral side with a large tension pneumothorax
- Distant or absent breath sounds
- Hyperresonance on percussion
- Decreased tactile fremitus
- Cardiovascular - Jugular venous distension (tension pneumothorax)
- Neurologic - Altered mental status
- Patients who are mechanically ventilated are difficult to ventilate during resuscitation. High peak airway pressures are a clue to an impending pneumothorax. A tension pneumothorax causes progressive difficulty with ventilation as the normal lung is compressed. On volume-control ventilation, this is indicated by marked increase in both peak and plateau pressures, with relatively preserved peak and plateau pressure difference. On pressure control ventilation, tension pneumothorax causes sudden drop in tidal volume. However, these observations are neither sensitive nor specific for making the diagnosis of pneumothorax or ruling out the possibility of pneumothorax.
Causes
- Smoking
- Of patients with primary spontaneous pneumothoraces, 91% reportedly are smokers or ex-smokers.
- The risk of primary spontaneous pneumothorax is directly dose related to smoking, with 102-times higher incidence rates in males who smoke heavily (ie, >22 cigarettes/d), compared to a 7-fold increase in males who smoke lightly (1-12 cigarettes/d).
- The following diseases can be associated with pneumothorax:
- Chronic obstructive lung disease
- Asthma HIV infection PCP
- Necrotizing pneumonia
- Bronchogenic carcinoma
- Sarcomas metastatic to the lungs
- Tuberculosis
- Cystic fibrosis
- Interstitial lung diseases associated with connective tissue diseases
- Idiopathic pulmonary fibrosis
- Sarcoidosis
- Lymphangioleiomyomatosis
- Langerhans cell histiocytosis
- Trauma - Penetrating and nonpenetrating injury
- Rib fracture
- Iatrogenic
- Transthoracic needle aspiration
- Transbronchial biopsy
- Thoracentesis
- Central venous catheter insertion
- Intercostal nerve block
- Tracheostomy
- Cardiopulmonary resuscitation
- Positive pressure ventilation
- Acupuncture
- Tall, thin stature in a healthy person or a person with Marfan syndrome
- High-risk occupation (eg, diving, flying)
- Thoracic endometriosis leading to catamenial pneumothorax - Occurs mostly in women aged 30-40 years (related to menses)
Esophageal Spasm
Myocardial Ischemia
Pericarditis, Acute
Pleurodynia
Pulmonary Embolism
Other Problems to be Considered
Large bulla can simulate pneumothorax on chest radiographs, thus requiring CT scan to clarify the diagnosis.
Occasionally, skin folds on chest radiographs mimic the pleural line.
Lab Studies
- Arterial blood gas - In patients with severe underlying lung disease and in those with persistent respiratory distress despite treatment
- Hypoxemia occurs with increased alveolar-arterial oxygen tension gradient.
- Hypoxemia tends to be more severe in patients with secondary spontaneous pneumothoraces.
Imaging Studies
- Chest radiograph (confirms pneumothorax)
- A linear shadow of visceral pleura with lack of lung markings peripheral to the shadow may be observed, indicating collapsed lung.
- In supine patients, deep sulcus sign with radiolucency along costophrenic sulcus may help to identify occult pneumothorax.
- Mediastinal shift toward the contralateral lung may also be apparent.
- Small pleural effusions commonly are present and increase in size if the pneumothorax does not reexpand.
- Confirmation of a suspected pneumothorax that is not readily observed on standard supine anteroposterior (AP) radiograph can be demonstrated by obtaining a lateral decubitus film with the involved hemithorax positioned uppermost.
- Rib films are indicated if the patient has localized rib pain. They also are indicated when evaluating the patient's posttrauma status if nothing is found on the main posteroanterior (PA) and lateral films.
- CT scan is not recommended for routine use but can help to accomplish the following:
- Distinguish between a large bulla and a pneumothorax
- Indicate underlying emphysema or emphysemalike changes
- Determine the exact size of the pneumothorax, especially if it is small
- Confirm the diagnosis of pneumothorax in patients with head trauma who are mechanically ventilated
- Method to estimate the fractional size of pneumothorax:
- Calculate the ratio of the transverse radius of the pneumothorax (cubed) to the transverse radius of the hemithorax (cubed).
- To express the pneumothorax size as a percentage, multiply the fractional size by 100.
- CT is not routinely recommended for the evaluation of spontaneous pneumothorax. However, because of the inherent superiority of CT scans to visualize the details of lung parenchyma and pleura, CT scans are widely used in actual clinical practice to assess the possibility of associated concurrent pulmonary disease.
- Ultrasonography is increasingly used in the acute care setting as a readily available bedside tool, especially in ICU and emergency departments. Ultrasonography has been shown to have high sensitivity (95.65%), specificity (100%), and diagnostic effectiveness (98.91%) for pneumothorax when using CT as the criterion standard.
Medical Care
All patients with pneumothorax must stop smoking in order to reduce the risk of recurrent pneumothorax. Administer oxygen to all patients. Treatment goals are air evacuation, lung reexpansion, and prevention of recurrence. Most patients are admitted to the hospital.
Treatment for primary spontaneous pneumothorax includes observation, simple aspiration, and chest tube placement.
Secondary spontaneous pneumothorax usually requires chest tube placement, as does traumatic pneumothorax.
Iatrogenic pneumothorax is frequently treated with observation or simple aspiration.
Tension pneumothorax is a medical emergency that requires immediate needle decompression and chest tube placement.
Recurrent spontaneous pneumothorax requires more definitive treatment to prevent recurrence.
- Simple observation is appropriate for asymptomatic patients with a minimal pneumothorax ( <15% of the hemithorax) and without evidence of persistent air leak by radiographic assessment. Unrecognized air leaks can be fatal. The average hospital stay is 2.8 days.
- Oxygen administration at 3 L/min nasal canula or higher flow treats possible hypoxemia and is associated with a 4-fold increase in the rate of pleural air absorption over room air alone.
- Monitoring pneumothorax size during this time is important.
- No protocols regarding serial radiography or imaging exist; the clinician typically reviews serial vital signs and clinical assessments, using the direction and rate of change in the clinical status to select imaging frequency.
- Simple aspiration (thoracentesis) is performed by placing a plastic catheter over the needle into the pleural space.
- The puncture site is commonly in the second or third intercostal space in the midclavicular line or in the fourth or fifth intercostal space over the superior rib margin in the anterior axillary line.
- The skin is prepared with Betadine solution and is covered with sterile drapes.
- Local anesthesia is performed with 1% Xylocaine solution.
- Use a 3-way stopcock and large syringe to evacuate air. When no more air can be aspirated or the patient suddenly coughs, the lung most likely has reexpanded.
- Remove the catheter, and massage the insertion site with sterile gauze to seal the channel into the pleural space.
- Most authorities consider this procedure to be the first-line treatment of pneumothorax, although the recurrence rate is high, particularly with secondary spontaneous pneumothoraces.
- Studies show a 55-75% success rate, with a hospital stay of 2.3 days. A follow-up chest radiograph is required.
- Chest tube thoracostomy is usually reserved for patients with first-time secondary spontaneous pneumothoraces. Almost all patients with COPD require a chest tube.
- A small-bore catheter (eg, 7-14F) is safe to use in most patients. Use a larger tube (eg, 28F) to reduce resistance in patients who are ventilated and at greater risk for air leaks. Keep the tube in place for 24 hours after the air leak ceases.
- Air leaks resolve within 7 days of treatment 80% of the time, with an average hospital stay of 5 days.
- A Heimlich valve allows for complete evacuation of air that is not under tension. Heimlich valves do not require suction and eliminate the chance of a tension pneumothorax; they allow greater mobility and less discomfort for the patient.
- These valves may expedite discharge or prevent admission and are good for transport of an injured patient.
- By decreasing the length of the hospital stay and allowing for outpatient care, medical costs are reduced as well.
- Heimlich valves are crucial in the care of patients with AIDS who have a median length of 20 days of chest tube placement.
- Tension pneumothorax is an emergency. Treat this emergency by inserting a large-bore needle into the pleural space through the second or third anterior intercostal space. A gush of air confirms the diagnosis. Leave the needle in place until the chest tube is placed.
Surgical Care
Procedures that may prevent the recurrence of spontaneous pneumothoraces include the following:
- Chest tube with instillation of sclerosing agent (pleurodesis)
- A patient treated with this procedure has a recurrence prevention rate of greater than 90%.
- Talc is the preferred agent for pleurodesis. It can be administered by insufflation or as a slurry.
- Video-assisted thoracoscopic surgery (VATS) with resection of large bullous lesions and/or insufflation of talc and thoracotomy are considered the most definitive treatment, with a recurrence rate of 2-14% and 0-7%, respectively. While VATS is used to prevent recurrence, not every patient with pneumothorax requires VATS.
- Indications for surgical assistance
- Persistent air leak for more than 7 days
- Recurrent ipsilateral pneumothorax
- Contralateral pneumothorax
- Bilateral pneumothorax
- First-time presentation in a patient with a high-risk occupation (eg, diver, pilot).
- Patients with AIDS often need this intervention because of extensive underlying necrosis.
- The risk of recurrent pneumothorax may also be unacceptable for patients with plans for extended stays at remote sites.
- Complications of surgical procedures include the following:
- Failure to cure the problem
- Acute respiratory distress and/or failure
- Infection of the pleural space
- Cutaneous or systemic infection
- Persistent air leak
- Reexpansion pulmonary edema
- Prolonged tube drainage and hospital stay: A study of management of pneumothorax in lymphangiomyomatosis (LAM) reported that chemical pleurodesis and surgery were equally effective and were both superior to conservative therapy in preventing the recurrence of pneumothorax in LAM. The authors recommended that, because of the high recurrence rate, either procedure should be considered for the management of initial pneumothorax in these patients. On the other hand, both procedures were found to be associated with increased risk of postoperative bleeding after lung transplantation, without affecting the length of hospital stay.
Consultations
- Patients requiring a chest tube, pleurodesis, or surgical thoracotomy and thoracoscopy require consultation with a surgeon.
- If patients have underlying lung disease, thereby increasing the chance of recurrence, consult a pulmonary specialist.
- Direct patients indicating a readiness to quit smoking to their primary care physician, or offer referral for cessation management. This may include nicotine replacement and non-nicotine pharmacotherapy such as bupropion.
The goals of pharmacotherapy are to reduce morbidity and to prevent complications. In addition to the medications listed below, talc may be used as a sclerosing agent for pleurodesis by mixing 2-5 g in 250 mL of sterile isotonic sodium chloride solution to form a slurry or poudrage. Acute respiratory distress syndrome (ARDS) has been reported after use of talc as a pleural sclerosing agent but is considered to be a rare complication
Drug Category: Local anesthetics
Used for thoracentesis and chest tube placement.
| Drug Name | Lidocaine hydrochloride (Xylocaine, Dilocaine, Anestacon) |
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| Description | Local anesthetic used as 1% solution. Onset of action is within 45-90 seconds. Duration of anesthesia is 10-20 min.
Adverse effects with use as local anesthetic include allergic reactions. |
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| Adult Dose | Dose varies with the procedure, local vascularity, and condition of patient; applied locally, not to exceed 4.5 mg/kg; do not repeat within 2 h |
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| Pediatric Dose | Not established |
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| Contraindications | Documented hypersensitivity to amide-type local anesthetics; avoid in Adams-Stokes syndrome and Wolff-Parkinson-White syndrome; avoid in severe sinoatrial, atrioventricular, or intraventricular block if artificial pacemaker not in place |
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| Interactions | Coadministration with cimetidine or beta-blockers, increases toxicity of lidocaine; coadministration with procainamide and tocainide may result in additive cardiodepressant action; may increase effects of succinylcholine |
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| Pregnancy | C - Safety for use during pregnancy has not been established.
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| Precautions | When used as local anesthetic, use proper technique to avoid intravascular administration; have resuscitative equipment available; adjust dose for older population, children, and patients who are critically ill or debilitated |
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Drug Category: Opiate analgetics
Used for pain control.
| Drug Name | Fentanyl citrate (Sublimaze, Fentanyl Oralet) |
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| Description | Onset of analgesia is immediate with IV use. Duration of analgesia is 30-60 min. Respiratory depressant effect may last longer than analgesia. |
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| Adult Dose | 0.5-1 mcg/kg/dose IV for minor procedures; may repeat dose at 30- to 60-min intervals |
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| Pediatric Dose | Not established |
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| Contraindications | Documented hypersensitivity, increased intracranial pressure, severe respiratory depression, severe liver or renal insufficiency |
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| Interactions | Phenothiazines may antagonize analgesic effects of opiate agonists; tricyclic antidepressants may potentiate adverse effects of fentanyl when both drugs are used concurrently |
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| Pregnancy | D - Unsafe in pregnancy
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| Precautions | Adjust the dose in renal insufficiency; inject slowly over 3-5 min; rapid IV infusion may cause skeletal muscle rigidity, impaired ventilation, apnea, bronchoconstriction, and laryngospasm |
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| Drug Name | Meperidine hydrochloride (Demerol) |
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| Description | Onset of analgesia occurs within 5 min. Titrate dose to effect. Half-life of the parent drug is 2.5-4 h, prolonged in patients with liver disease. Half-life of the active metabolite, normeperidine, is 15-30 h. Accumulates with high dose and renal insufficiency. |
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| Adult Dose | 50-150 mg/dose IV; can repeat in 3-4 h prn |
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| Pediatric Dose | Not established |
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| Contraindications | Documented hypersensitivity; MAOIs taken within the past 14 d |
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| Interactions | CYP2D6 enzyme substrate; phenytoin decreases analgesic effect; aggravates adverse effects of isoniazid; MAOIs, serotonin uptake inhibitors, CNS depressants, tricyclic antidepressants, and phenothiazines potentiate effects of meperidine; incompatible with aminophylline, heparin, phenobarbital, phenytoin, and sodium bicarbonate |
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| Pregnancy | D - Unsafe in pregnancy
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| Precautions | Use with caution in patients with pulmonary, hepatic, and renal disorders, with increased intracranial pressure, and with seizure disorders; tolerance and drug dependence can develop |
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Drug Category: Benzodiazepine
Used for conscious sedation.
| Drug Name | Midazolam hydrochloride (Versed) |
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| Description | Benzodiazepine used for sedation component of conscious sedation protocol. Onset of action occurs within 1-5 min. Half-life of 1-4 h. Prolonged with liver cirrhosis, congestive heart failure, obesity, and old age. |
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| Adult Dose | Initial dose: 0.5-2 mg IV over 2 min; slowly titrate to effect by repeating doses every 2-3 min; usual total dose is 5 mg; decrease initial dose in the older population to 0.5 mg IV; administer no more than 1.5 mg in a 2-min period, to a total dose of 3.5 mg |
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| Pediatric Dose | Not established |
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| Contraindications | Documented hypersensitivity; cross sensitivity with other benzodiazepines reported; concurrent use of protease inhibitors, eg, amprenavir and ritonavir |
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| Interactions | Sedative effects of midazolam may be antagonized by theophyllines; narcotics and erythromycin may accentuate sedative effects of midazolam because of decreased clearance |
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| Pregnancy | D - Unsafe in pregnancy
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| Precautions | May cause severe respiratory depression/arrest; monitor vital signs, including oximetry per institutional conscious sedation protocols; have appropriate resuscitative equipment available; caution with hepatic or renal impairment, in patients who are older or debilitated; may cause hypotension; causes CNS depression; causes retrograde amnesia; causes dependence and acute withdrawal syndrome |
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Further Outpatient Care
- Patients should receive follow-up care from a pulmonary physician within 7-10 days.
Deterrence/Prevention
- Patients should not travel by air or travel to remote sites until radiography shows complete resolution.
- Patients cannot smoke. They should be assessed as to readiness to quit, educated about smoking cessation, and provided with pharmacotherapy if ready to quit. Direct patients indicating a readiness to quit smoking to their primary care physician, or offer referral for cessation management. This may include nicotine replacement and non-nicotine pharmacotherapy such as bupropion.
Complications
- Respiratory or cardiac arrest
- Hemopneumothorax
- Bronchopulmonary fistula
- Pain at the site of chest tube insertion, infection, and hemorrhage
Prognosis
- Complete resolution of uncomplicated pneumothorax takes approximately 10 days.
Patient Education
Medical/Legal Pitfalls
- Imaging studies should not delay the diagnosis of tension pneumothorax. Tension pneumothorax is a medical emergency and requires immediate treatment.
- Chest radiographs may fail to reveal pneumothorax. Radiologists or emergency physicians may fail to recognize the presence of the pneumothorax. A vertical skin line can be mistaken for a pneumothorax, leading to unnecessary and possibly harmful therapy.
- Expiratory chest radiographs do not improve detection of pneumothorax after procedures with the potential to cause a pneumothorax.
- A high index of suspicion for tension pneumothorax is recommended in patients on mechanical ventilation with acute onset of hemodynamic instability, difficult ventilation with high inspiratory pressures, and worsening hypoxemia and/or hypercapnia, even with a functioning chest tube in place. Portable chest radiograph may fail to show the pneumothorax; CT may be required for diagnosis.
- Always consider pneumothorax in the differential diagnosis of major trauma.
- Spontaneous pneumothorax is a life-threatening condition in patients with severe underlying lung disease.
- CT scan of the chest is the most reliable imaging study for the diagnosis of pneumothorax.
| Media file 2:
Small spontaneous primary pneumothorax. Close view of patient from picture 1. |
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| Media file 3:
Expiratory radiograph of small spontaneous primary pneumothorax of patient from pictures 1 and 2. |
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| Media file 4:
Spontaneous primary pneumothorax due to left upper lobe bleb. |
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| Media file 5:
Spontaneous primary pneumothorax due to left upper lobe bleb. Close view of patient from picture 4. |
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| Media file 8:
Small pneumothorax in a patient with idiopathic pulmonary fibrosis, following video-assisted thoracoscopic surgery (VATS) lung biopsy. |
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| Media file 9:
Small pneumothorax in a patient with idiopathic pulmonary fibrosis, following video-assisted thoracoscopic surgery (VATS) lung biopsy. Close view of the patient from picture 8. Note that the hole on a chest tube is outside the pleural space. |
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| Media file 10:
New left-sided pneumothorax in a patient on mechanical ventilation, requiring high inflation pressures. |
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Pneumothorax excerpt Article Last Updated: Aug 17, 2006
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