Fonte: Rachel Liu, BAO, MBBCh, Emergency Medicine, Yale School of Medicine, New Haven, Connecticut, EUA
Um pneumotórax de tensão é uma situação de risco de vida em que o excesso de ar é introduzido no espaço pleural ao redor do pulmão, seja através de trauma na cavidade torácica ou como um vazamento espontâneo de ar do próprio pulmão. O ar preso no espaço pleural causa a separação do pulmão da parede torácica, interrompendo mecanismos normais de respiração. Pneumotórax pode ser pequeno sem conversão à tensão, mas quando há uma quantidade significativa e crescente de ar preso na cavidade pleural, a pressão crescente deste ar anormal faz com que o pulmão encolham e entrem em colapso, levando a problemas respiratórios. Essa pressão também afasta o mediastino (incluindo o coração e grandes vasos) de sua posição central, causando a incapacidade de o sangue de retornar ao coração e diminuindo a saída cardíaca. Pneumotóraces de tensão causam dor no peito, falta de ar extrema, insuficiência respiratória, hipóxia, taquicardia e hipotensão. Eles precisam ser aliviados emergentemente quando um paciente está nos extremos.
Os pneumotóraces de tensão são definitivamente gerenciados por procedimentos que permitem a remoção do ar preso, como a inserção de um tubo torácico. No entanto, os materiais para colocação de tubo torácico normalmente não estão disponíveis fora do ambiente hospitalar. Medidas temporizantes são necessárias na deterioração dos pacientes antes da chegada do hospital ou enquanto os materiais do tubo torácico estão sendo coletados. Nessas situações, é realizada a toracostomia urgente da agulha (também chamada de “descompressão da agulha”). Simplesmente, é a inserção de uma agulha de grande furo ou cânula através da parede do peito e no espaço pleural para permitir que o ar dentro da cavidade pleural escape. Se um cateter ou cânula não estiver disponível imediatamente, o procedimento pode ser realizado com uma agulha longa e grande presa a uma seringa. O ar pode ser aspirado para fora do espaço pleural com a seringa. Uma agulha metálica não pode ficar na cavidade pleural, pois a ponta afiada pode causar mais danos; assim, ele precisaria ser removido da parede do peito uma vez que o ar é aspirado.
Needle thoracostomy is a relatively easy procedure to temporize a patient in extremis from a tension pneumothorax before a chest tube can be placed. Penetration of the chest wall muscle, subcutaneous tissue, and pleura may require significant force, so a stabbing motion of needle entry may be necessary. The most common reason for failure of this procedure is that the needle length is not sufficient enough to reach the pleura. Some patients have significant chest wall thicknesses that standard needles may not penetrate. Because of this, some suggest a lateral approach in the fourth or fifth intercostal space, in the anterior axillary or mid-axillary lines.
Risks include damage to the internal thoracic artery and intercostal nerves, which run underneath each rib. Bleeding may be significant, and may lead to hemothorax. This is the reason for performing the procedure above the third rib in the second intercostal space. Inappropriate positioning may risk subclavian artery laceration, pulmonary artery laceration, or lung parenchyma injury-all causing post-procedure bleeding. It may also cause iatrogenic creation of simple pneumothorax. As the catheter is a foreign body, pneumonia, empyema or local skin infections may develop.
Relative contraindications include prior thoracotomy, pneumonectomy, or pleurodesis, and these conditions may cause false alarm, as breath sounds are often absent after these conditions. Also, care must be taken with those in coagulation disorders, as bleeding complications may arise post-procedure. However, a tension pneumothorax is life threatening, and emergent treatment takes priority.
Needle thoracostomy, also known as “needle decompression” is a procedure performed to stabilize deteriorating patients in the life-threatening situation of a tension pneumothorax. To put it simply, the procedure involves inserting a large bore needle or cannula through the chest wall into the pleural cavity — to allow the air from within to escape.
In this video, we will first review the cause — pneumothoraces. Then, we will describe the needle thoracostomy procedure — including the prepping steps and the technique for needle insertion. Lastly, we will discuss the possible complications and contraindications associated with this intervention.
First let’s briefly talk about the etiology and types of pneumothoraces.
A pneumothorax occurs when excess air is introduced into the pleural space surrounding the lung. This may happen by trauma to the chest cavity, or due to a spontaneous leak from the lung itself. The result is separation of the lung from the chest wall and disruption of normal breathing mechanisms.
In case of a simple pneumothorax, the air can both enter and exit the pleural cavity. Hence, there is no pressure build up. Whereas in case of a tension pneumothorax, the air only enters the cavity. Thus, there can be substantial air entrapment, resulting in increased pressure or “tension”, which forces the lung to shrink and collapse. This leads to respiratory distress and the increasing pressure further displaces the mediastinum including the heart and the great vessels away from its central position, causing diminished return of the blood to the heart and therefore decreased cardiac output. A tension pneumothorax causes chest pain, extreme shortness of breath, respiratory failure, hypoxia, tachycardia and hypotension. Therefore, the “tension” needs to be relieved emergently when a patient is in extremis.
One of the methods to relieve the pressure is by needle thoracostomy – the technique that the following sections will explain.
Start by gathering the necessary supplies. These include chlorhexadine or betadine solution, an at least 2 inches long 14 or 16 gauge catheter or angiocatheter, and tape.
After performing the physical assessment steps, administer supplemental oxygen to the patient, using a nasal cannula or a non re-breather mask. Place the patient in a supine flat position, or if possible, seated with the bed elevated to a 45° angle, depending on patient comfort. Identify the second intercostal space on the affected side. It corresponds with the Angle of Louis formed by the junction of the manubrium and the sternum. Follow it to the mid-clavicular line. The landmark of needle insertion is at the intersection of second intercostal space and the mid-clavicular line. You may also perform the above procedure in the anterior axillary or mid-axillary line at the level of the fourth or fifth intercostal space. A more superior insertion site is preferred to avoid penetration into the abdominal cavity. After locating the landmark, sterilize the space using an antiseptic, like chlorhexadine. Next, place the long large bore cannula onto a sterile field and put on sterile gloves. You are now ready to perform the needle decompression.
Insert the cannula at a 90° angle to the chest wall in the mid-clavicular line, in the 2nd intercostal space above the third rib. This is to avoid damaging neurovascular structures that lie immediately below each rib. The insertion should be done in one motion and may require forceful entry. Make sure to insert the cannula to nearly its hub to reach adequate depth. A “pop” will be felt when the needle penetrates the pleura, and a rush or “hissing” of air through the needle will be audible.
Alternatively needle decompression may also be performed using a cannula attached to a 10ml syringe, which can offer better grip when puncturing the chest wall and pleura. There are two methods for doing this. The first method uses an empty syringe. Attach the syringe to the cannula and puncture the chest wall and pleura as described previously. The air escaping the pneumothorax should push plunger up — confirming appropriate depth. At the point you can remove the syringe. The second method uses a 10ml syringe half-filled with fluid, such as saline or water, attached to the cannula. Leave about 1ml of air between the fluid and the syringe’s plunger. Next, perform needle decompression, and when the pleura is punctured the pneumothorax will cause the fluid in the syringe to bubble. Remove the syringe and the metal needle of the cannula so that only the plastic catheter remains. Secure the catheter with tape.
Reassess the patient for clinical improvement. This is signified by patient appearance of less discomfort or agitation, fuller respirations taken, ability to speak more complete sentences, less tachypnea or tachycardia, improvement in hypoxia and blood pressure, and resolving tracheal deviation. If patient’s condition does not improve, repeat needle decompression by inserting another long large bore cannula adjacent to the first. Alternatively, you can move straight to chest tube placement covered in another video of this collection.
“Needle thoracostomy is a relatively easy procedure to temporize a patient in extremis before a chest tube can be placed. Penetration of the chest wall muscle, subcutaneous tissue and pleura may require significant force, so a stabbing motion of needle entry may be necessary. The most common reason for failure of this procedure is that the needle length is not sufficient enough to reach the pleura. Note that some patients have significant chest wall thicknesses that standard needles may not penetrate. Because of this, some suggest a lateral approach in the fourth or fifth intercostal space, in the anterior axillary or mid-axillary lines.”
“Risks include damage to the internal thoracic artery and intercostal nerves, which run underneath each rib. Bleeding may be significant, and may lead to hemothorax . Inappropriate positioning may risk subclavian artery, pulmonary artery laceration, or lung parenchyma injury, all causing post-procedural bleeding. It may also cause iatrogenic creation of simple pneumothoraxes. As the catheter is a foreign body, pneumonia, empyema, or local skin infection may develop.”
“Relative contraindications include prior thoracotomy, pneumonectomy or pleurodesis. Also care must be taken for those with coagulation disorders, as bleeding complications may arise post-procedure. However, a tension pneumothorax is life-threatening and emergent treatment takes priority.”
You’ve just watched JoVE’s illustration of needle thoracostomy. This is a lifesaving procedure, and although the steps are straightforward and uncomplicated, a successful procedure requires good knowledge of the surface anatomy, dexterity, and confidence. As always, thank you for watching!
