Print version ISSN 0034-7094
Rev. Bras. Anestesiol. vol.54 no.5 Campinas Sept./Oct. 2004
Tension pneumothorax in post-anesthetic care unit. Case report*
Pneumotórax hipertensivo en la sala de recuperación pos-anestésica. Relato de caso
Ana Claudia Chiaratti Mega, M.D.I; José Mário Mangaravite Encinas, M.D.I; Natasha Pinheiro Blanco, M.D.II; Tatiane Mury Martins, M.D.II
IAnestesiologista do CET/SBA Hospital
Municipal Souza Aguiar
IIME1 do CET/SBA Hospital Municipal Souza Aguiar
BACKGROUND AND OBJECTIVES: The incidence
of pneumothorax after penetrating chest trauma is 100%. Tension pneumothorax,
a high mortality rate condition, may be triggered, among other causes, by pulmonary
injury not previously identified, and may also be associated to mechanical ventilation.
This report presents a case of tension pneumothorax diagnosed in the Post-Anesthetic
Care Unit (PACU).
CASE REPORT: A 34-year-old black male patient, physical status ASA I E, victim of gunshot wound was submitted to explorative laparotomy and right femoral artery and vein exploration under general balanced anesthesia with rapid sequence induction. The patient kept hemodynamically stable throughout the procedure. However, in the PACU patient presented hemodynamic instability with respiratory failure, sweating, tachycardia and hypertension. Chest CT-scan revealed right hemopneumothorax, which was immediately drained. Patient was then transferred to the Intensive Care Unit, where he progressively improved to be discharged from the hospital 22 days later, without sequelae.
CONCLUSIONS: Tension pneumothorax is a fatal condition which may be easily identified through clinical and radiological evaluations. It should be always suspected in the presence of chest trauma and, in this case, immediate chest drainage should be performed prior to mechanical ventilation or any surgical procedure.
Key Words: COMPLICATIONS: pneumothorax; SURGERY, Trauma
JUSTIFICATIVA Y OBJETIVOS: Hay 100% de
prevalencia de pneumotórax en los casos de trauma penetrante torácico,
siendo que el pneumotórax hipertensivo puede ser desencadenado, entre otras
causas, por una lesión pulmonar no diagnosticada inicialmente, o asociado
a la ventilación mecánica, presentando alta tasa de mortalidad. El
objetivo de este relato es presentar un caso de pneumotórax hipertensivo
diagnosticado en la Sala de Recuperación Pós-Anestésica (SRPA).
RELATO DEL CASO: Paciente del sexo masculino, 34 años, estado físico ASA I E, víctima de lesiones por arma de fuego. Fue sometido a laparotomía exploradora y exploración de arteria y vena femoral a derecha, sobre anestesia general balanceada con inducción en secuencia rápida, con estabilidad hemodinámica durante todo el procedimiento quirúrgico. En la SRPA, presentó instabilidad hemodinámica, con insuficiencia respiratoria, sudoresis, taquicardia e hipertensión arterial. La tomografía computadorizada de tórax evidenció hemoneumotórax a la derecha, siendo inmediatamente drenado. Fue transferido para el Centro de Terapia Intensiva, presentó mejora progresiva del cuadro, con alta hospitalar, sin secuelas, después de 22 días.
CONCLUSIONES: El pneumotórax hipertensivo es una enfermedad letal que puede ser fácilmente reconocida a través del examen clínico y radiológico; debiendo ser siempre sospechado en la presencia de traumatismo torácico, y en este caso, se debe realizar inmediatamente el drenaje de tórax antes de la ventilación mecánica y de procedimientos quirúrgicos.
Postoperative pulmonary complications are still significant anesthetic-surgical problems because they are associated to longer hospital stay 1. Anesthesia-related complications have a morbidity/mortality rate of 7.6% to 10.6% during surgery, and of 3.1% to 5.9% in the post-anesthetic care unit (PACU) 2, which may be directly related to anesthesia or secondary to it 3.
Trauma patients may present complications inherent to the trauma itself or triggered by the interaction of early or late acute physical status deteriorations and acute or insidious manifestations 4. So, there might be non-diagnosed injuries during initial evaluation resulting in major intra or postoperative complications. Approximately 90% of significant injuries not previously identified may be diagnosed in the PACU 5. Such complications should be judiciously analyzed not to be mistaken by anesthetic complications 3.
Pneumothorax is the build up of air between parietal and visceral pleurae, leading to increased intrathoracic pressure and ipsilateral pulmonary tissue collapse, resulting in severe ventilation-perfusion ratio abnormality, decreased vital capacity, minute volume and venous return, which lead to hypoxia by pulmonary shunt increase 6,7.
Tension pneumothorax is developed when the air gets to the pleural space through a unidirectional valve in the lung or chest wall. As a consequence, interpleural pressure is progressively increased, collapsing ipsilateral lung and contralaterally displacing mediastinum and trachea. The healthy lung is also compressed. Venous return and cardiac output suffer great decrease, with rapid deterioration of vital signs. A simple pneumothorax may become tension pneumothorax when positive pressure mechanical ventilation is installed 4,6,7.
Pneumothorax should always be considered after central venous access, brachial plexus block, intercostal block, fractured rib, tracheostomies, nephrectomies and other retroperitoneal or intra-abdominal procedures, laparoscopies and after closed or penetrating lung trauma. In the latter, its incidence is 100% 7,8.
This report aimed at presenting a case of tension pneumothorax diagnosed in the PACU in a patient with gunshot wound in the left supramandibular and right inguinal regions.
A 34-year-old black male patient, 90 kg, 190 cm, physical status ASA I E, victim of gunshot injuries in the left supramandibular and right inguinal regions, was submitted to laparotomy with surgical exploration of right femoral artery and vein, where no femoral vessels and/or abdominal viscerae injuries were found.
At preanesthetic evaluation, patient was lucid, oriented, sweating, normally rosy, acyanotic, eupneic, hydrated, with full peripheral pulses and satisfactory capillary filling. He was hemodynamically stable, with BP 130 x 90 mmHg, heart rate 90 bpm and 96% arterial oxygen saturation. There were no lab or radiological tests at this time.
Monitoring consisted of continuous ECG, noninvasive blood pressure measurement, capnometry, capnography and urinary output. Two peripheral veins were punctured with 16G venous catheter and hydration was started with lactated Ringers solution.
We decided for general balanced anesthesia with rapid sequence induction. After pre-oxygenation, intravenous induction was started with 150 µg fentanyl, pre-curarization with 5 mg atracurium, 150 mg propofol and 100 mg succinylcholine. Sellicks maneuver was performed after loss of ciliary reflex and tracheal intubation was achieved in the first attempt with 8.5 mm cuffed tube.
Anesthesia was maintained with enflurane, atracurium and fentanyl. Ventilation was mechanically controlled with the following parameters: TV 750 mL, RR 12 irpm, I:E ratio 1:2 and 2 l of FAG with 100% oxygen. There was no hemodynamic instability or the need for blood transfusion throughout the surgery. At surgery completion, neuromuscular block was reversed with 1 mg atropine and 2 mg neostigmine. At this point, blood was observed in the tracheal tube during airways aspiration. We then decided to keep the patient with the tracheal tube, sedated and under neuromuscular block.
At PACU admission, ventilatory prosthesis with Narcolog in circle system was installed with double canister CO2 absorber, 750 mL TV, RR 12 irpm, I:E ratio 1:2, 2 l FAG and 100% FiO2. Monitoring consisted of ECG, pulse oximetry and noninvasive blood pressure. Forty minutes later, patient presented decreased arterial oxygen saturation (94%-90%), sweating, tachycardia, hypertension (150 x 90 mmHg) and inspiratory pressure above 40 cmH2O. Pulmonary auscultation showed decreased left murmur and crepitation in both bases; chest X-ray in AP in bed was then requested. Situation has rapidly deteriorated, with worsening of hypoxia before X-ray. Patient was then immediately transferred to the Imaging Sector.
During transportation, patient was monitored with pulse oximetry and heart rate. Ventilation was performed with 100% oxygen, 10 L.min-1 in an open system with Rubens valve. There was a progressive worsening of symptoms, with intense sweating, tachycardia, increased airway resistance (difficult ventilation), bloody secretion thru the tracheal tube and oxygen hemoglobin saturation of approximately 70% to 60%. Chest CT-scan has revealed extensive right hemopneumothorax with contralateral mediastinum displacement and a bullet located in infra-hepatic fat (Figure 1A and Figure 1B). Righ hemithorax was immediately drained with removal of large amounts of air and 100 mL blood. Soon after, patient was transferred to the Intensive Care Unit.
At ICU admission, patient presented hemodynamic instability, hypoxia, hypercabia and hypovolemic shock. Situation has improved after volume replacement with crystalloids and 2 units of red cells concentrate, as well as mechanical ventilation with Bird® device (FiO2 0.6, 14 irpm, PEEP 5 cmH2O). Chest drain showed drainage below 70 mL.h-1, with no need for further surgery. There was then a progressive improvement of patients clinical condition, and he was discharged from the hospital 22 days later, without sequelae.
This case shows the evolution of a respiratory complication in the PACU triggered by the association between a gunshot lung injury not diagnosed in the initial evaluation and positive pressure mechanical ventilation, leading to tension pneumothorax development, which reinforces the increased risk of postoperative complications with injuries not previously detected 9.
Respiratory failure in the PACU tends to be hypoxemic-hypercabic and of ventilatory origin. Hypoxia is caused by hypoventilation and/or increased right-left pulmonary shunt, with changes in ventilation-perfusion ratio, as can be seen during tension pneumothorax. Hypoxia, however, may be difficult to identify in severely ill patients, because signs/symptoms may be masked or related to other causes 5. Cyanosis is not a good evaluation index for hypoxia because, to become apparent, it requires oxygen hemoglobin saturation to fall below 75% 4. Arterial blood gases analysis will show signs of respiratory failure, hypoxia and hypercarbia. However, pulse oximetry associated to clinical evaluation and history is better in diagnostic terms 5,7,9. Pneumothorax does not produce severe symptoms unless it involves more than 40% of pulmonary volume or it occurs in a patient with preexisting pneumopathy, as well as if it becomes hypertensive 7.
Tension pneumothorax may be present in 50% of hemothorax cases with clinical history of contusing or penetrating chest trauma, dyspnea, cyanosis, agitation, tachycardia, diaphoresis, jugular vein distension, trachea and contralateral mediastinum displacement 5. Usually, pneumothorax and hemothorax are concomitant. Hemothorax is present in 70% of major pulmonary injuries, and to be radiologically visible, there must be more than 500 mL build up or 20% pulmonary volume involvement.
CT-scan is the best way to confirm diagnosis 5,7. Bleeding may come from pulmonary parenchyma vessels or from intercostal, subclavian or other major vessels, leading to hypovolemia, decreased pulmonary sounds, as well as trachea and mediastinum displacement. No surgery is needed in 80% of cases of hemothorax 7, being thoracotomy or videothoracotomy indicated only in the presence of hypotension persistent to volume replacement, bleeding above 300 mL.h-1 for four hours, continuous massive hemorrhage above 2000 mL and left hemothorax with mediastinum widening 10.
Among different post-trauma ventilatory changes, tension pneumothorax is extremely severe, may lead to death and is considered a surgical urgency. Once diagnosed, regardless of its extension, it should be treated with chest drainage before tracheal intubation and positive pressure ventilation 3,5,7. The conclusion then is that clinical evaluation of trauma patients is of paramount importance for evolution and prognosis, and the possibility of hidden, potentially fatal injuries, should be taken into consideration.
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Dra. Ana Claudia Chiaratti Mega
Rua Pinheiro Guimarães, 115/906 Bloco I
22281-080 Rio de Janeiro, Brazil
Submitted for publication October 27, 2003
Accepted for publication January 29, 2004
* Received from do Hospital Municipal Souza Aguiar, Rio de Janeiro, RJ