PNEUMOTHORAX

 

Etiology:

  1. Spontaneous = also called  "Simple". Air accumulates in pleural space. Causes  include COPD, Marfan, inhalation with negative pressure, diving, asthma, emphysema, PNA, lung CA, trauma, subclavian line placement, pulmonary  fibrosis.
     
  2. Open =2ry to chest trauma , external wound through chest wall or through esophagus,  or trachea communicates with pleural cavity, "sucks" the air  in and out, with mediastinal to-and-fro shift during respiratory cycle and collapse of ipsilateral lung with every  inspiration. Consequently, poor  ventilation and hypoxia occur. Physiologically, above occurs if wound is larger than 2/3 of  trachea. This PNTX also called  Sucking Chest Wound.
     
  3. Tension = common causes are any of the causes of spontaneous PNTX and mechanical ventilation. Also, if pt has simple PNTX and intubation is performed without prior insertion of chest tube, the simple PNTX  will convert to tension PNTX. Thus, if  PNTX is suspected and one considers ET intubation,  placement of chest  tube prior to intubation is warranted.  In  tension PNTX one-way valve is formed, air enters without possibility of escape, and causes controlateral shift of  trachea, mediastinum and great vessels with consequent  cardiovascular collapse.
     
  4. Hemothorax = 2ry to blunt or penetrating trauma.

S & S:

  1. Spontaneous - c.p., dyspnea, tachypnea, ¯ BS,  hyperresonance to percussion. Hypoxia,  O2% SAT depend on the size (% of PNTX).  SQ emphysema may be present.
     
  2. Open =  in addition to above S & S, gives the "sucking" sound and visible wound.
     
  3. Tension = sudden onset of c.p. with CV collapse, tachycardia, controlateral  tracheal deviation, distended neck vein, ¯ BS on affected side.
     
  4. Hemothorax = in addition   to ¯BS, tachypnea and dyspnea pt may develop signs of hypovolemia  and dullness on percussion.

DX:

  1. Spontaneous = hx, S & S, Cxray. CXray  is most sensitive if  done  in inspiratory/expiratory phase. One looks for absence of  vascularity (marking)  in periphery, hyperlucency (black) and the pneumothorax line must track all the way along  the lung field to avoid confusion with scapula, cloth or skin fold. To calculate the  PNTX size the rough estimate is 1 cm, 2 cm or 3 cm  thick, 10%, 20% and or 30%  of  PNTX is present, respectively. If suspicion is high but PNTX is not visible by xRay,  non-contrast CT is diagnostic. However, it is debatable whether CT is needed if the xray doesn't reveal PNTX, since its  small size  won't require any treatment.
     
  2. Open - diagnosis is clinical.
     
  3. Tension - diagnosis must  be only clinical. You do not have time to take xRay.
     
  4. Hemothorax -at least 200-250 ml of blood needed to blunt costovertebral angles on upright Cxray.

Treatment:

  1. All pts require O2 therapy and O2 SAT monitor. Heplock, IVF and cardiac monitor PRN.
     
  2. Spontaneous - If  PNTX is > 20%, chest tube is placed. PNTX of <10% generally requires no treatment.  If the PNTX is >10%  but < 20%, possibilities are:
     
    1. 16 G needle attached to 3-way stopcock and syringe inserted into 2d or 3d midclavicular line. Air is aspirated with syringe and then discarded via stopcock. CxRay is done after the procedure and 6-8 hrs. later, and if no PNTX pt is DC with F/U in 24 hrs.
    2. One-way valve catheter inserted also in 2d -3d midclavicular space. Usually CxRay is repeated to see  the outcome and pt can be DC home with valve.
    3. PNTX of <10% generally requires no treatment. In this case applying 100%
      O2 can be therapeutic. O2 works by eliminating and displacing Nitrogen
      gases.

  As many as 30% of spontaneous PNTX  are recurrent after first episode and  pleuroadhesis is performed, which on xRay  may appear as scarring.

     3.  Open - a square dressing is applied on top of wound and taped on three sides.
          This way, during  inspiration dressing adheres to the wound and prevents further
          air entrance, while with expiration air  escapes through the fourth opening of the
          dressing. Chest tube is placed  ASAP (and prior  to intubation) at a site distant 
          to wound.  The dressing now can be taped on the 4th  side. Open wound is
          repaired when pt's conditions allows.
     4.  Tension - immediate placement of 14 G needle into 2d IC space at the
          midclavicular line.Gush of air is heard and pt's VS improve immediately. 
          The procedure is followed by placement of chest tube.
     5.  Hemothorax - 36 Fr chest tube placed and directed posteriorly.  If  1500 ml 
          of blood is drained upon chest tube insertion, transfusion and immediate
          thoracotomy in order to clamp the bleeding vessels are required. Also, if after the
          chest tube insertion, one continues to have ml/hr (2-3 ml/kg/hbloodr)  drainage,
          thoracotomy is indicated. Authors advocate autotransfusion if pt looses > 500 ml 
          of blood.

 
 

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