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A 23-year-old man was seen because
of acute onset of chest pain. The pain which occurred suddenly
in class about 2 hours ago was sharp and persistent, and
located over the left upper chest wall. There was no
radiation, migration or precipitating factors. The pain became
worsened while he was taking a deep breath that could be
slightly improved while holding the breath. Besides mild
breathlessness, he had been otherwise well in his daily
living. There was no fever, chills, palpitation, cold
sweating, cough in the past days, or belly discomfort. He was
a smoker (1 pack/day). He denied any history of trauma,
vigorous exercise or taking medicines. He had no family
history of chest disease.
On physical examination, he had
clear consciousness but was slightly anxious. His height was
185 cm and weight was 65 kg. The temperature was 36.9°C, the
pulse rate 95 beats per minute, and the respiratory rate 18
breaths per minute. Blood pressure while in supine position
was 140/80 mmHg. The arterial oxygen saturation while he was
breathing ambient air was 95%. The skin was no cyanosis,
petechiae, purpura or pigmentation. His conjunctivae were
pink, the sclerae were anicteric, and the pupils were isocoric
with prompt light reflexes. The neck was supple without
lymphadenopathy, engorged jugular veins, palpable thyroid
gland or carotid bruits. The chest wall movements decreased at
the left side, and breath sounds were mildly decreased over
the left upper side. The heart beats were regular without
audible murmur. The abdomen was unremarkable. His extremities
were freely movable without edema.
< Course and treatment
>
A left-sided
pneumothorax with partial collapse of the lung was confirmed
by a chest radiograph (Fig. 1
& 2).
Primary spontaneous pneumothorax was diagnosed. High flow
oxygen therapy (10 L/min) was administered. He received simple
aspiration using a syringe. Follow-up chest radiographs showed
that pneumothorax was stable and he felt better later. He was
discharged in a stable condition.
< Discussion
>
氣胸（pneumothorax）係指氣體不正常地聚積在肋膜腔中。氣體可以經過下述三途徑進入肋膜腔：通過臟層肋膜的破裂處；經胸壁、膈肌或氣管進入；肋膜腔有產氣微生物。一般分為自發性氣胸及受創性氣胸，前者尚可依據病因分為原發性自發性氣胸及續發性自發性氣胸；後者可分為醫療及非醫療造成之氣胸。
原發性自發性氣胸的發生率約為每十萬人中有10人，男性多於女性(5：1)，約三分之二的病患是40歲以下(20~40歲)，右側比左側多，兩側都發生的機會低，且通常非同時發生。患者多為瘦高型，吸煙者及HLA-A2B40陽性者也容易發生，大部分肇因於肺尖部位的囊泡(bleb)破裂，數目從一個到多個不等，約有20％可在X光上看見此囊泡，而在開胸手術中，則約有80％的病人可發現。為什麼易發生在瘦高型的患者身上？可能的原因是這些患者其肺頂部的肋膜腔負壓相對較大，長期下來較易形成肋膜下囊泡。
通常在靜息時發生，會突然出現尖銳性胸痛(92％)、呼吸困難(79％)及難咳嗽，數小時後，逐漸轉為鈍痛，約24至72小時後，縱使氣胸還存在，疼痛也會消失。呼吸困難往往出現在有大範圍
(＞40％體積)氣胸的患者，原發性自發性氣胸變成危及生命的張力性氣胸(tension
pneumothorax)的機率並不高(2~3％)。氣胸範圍小時，身體檢查可能正常，常見患側胸部變寬厚且呼吸時胸廓運動變小，缺乏觸覺震顫（absence
of tactile
fremitus），同時伴有呼吸音減低及叩響增強（hyperresonant）。胸部X光片可以確定診斷，小量氣胸僅在用力呼氣或側臥位投照的胸部X光片上才能發現。約20％自發性氣胸的患者會出現肋膜積液，如果在症狀出現後數小時內就發現積液，大概是血胸，來源多是一些肋膜腔沾黏斷裂後從壁層肋膜斷端流出來的。若隔一段較長時間才出現肋膜積液，則應該是回流的淋巴受阻，堆積在肋膜腔的淋巴液。不過，在胸痛、氣胸及合併肋膜積液的情況下，如再加上氣性縱膈，則食道破裂須列為鑑別診斷。心電圖的變化常為胸前導QRS振幅降低及軸偏移。
原發性氣胸發作時，80％以上的患者，都正處於休息或日常生活狀態，只有約9％的患者正在運動，所以說原發性氣胸沒有特定的誘發因素。原發性自發性氣胸五年內復發的可能性為30－50％，第二次發作後再發的機率為50%；第三次為62%；第四次為80％。
續發性自發性氣胸最常見的病因為慢性阻塞性肺病，其它則為肺結核、壞死性肺炎、氣喘、原發性或轉移性肺癌、肺纖維化等。
原發性自發性氣胸的治療方法有─觀察:氣胸範圍少且無症狀者,觀察即可不需特別治療，但仍需避免劇烈運動，氣胸內之氣體大多在1-2週內自行吸收。氧氣治療:可加速氣胸內之氣體吸收。針刺抽吸:效果有限，但常用於因壓力性氣胸造成休克現象，之後立即施行胸腔引流管置入術。胸腔引流管置入:嚴重呼吸困難之氣胸。胸腔鏡手術:兩次以上之復發性氣胸，利用胸腔鏡手術進行囊泡切除及肋膜沾黏術，手術傷口小且術後併發症少。開胸手術:大多被胸腔鏡手術取代。肋膜腔沾黏術
:利用化學性肋膜沾黏固定避免氣胸再次復發。
續發性自發性氣胸的治療與原發性氣胸一樣，但情況要緊急得多。因此， 幾乎所有續發性氣胸的患者都需放置胸腔引流管。
< References
>
- Chee CBE, Abisheganaden J, Yeo JKS,
et al: Persistent air-leak in spontaneous pneumothorax:
clinical course and outcome, Respir Med 92: 757-761, 1998.
- Henry M, Arnold T, Harvey J: BTS
guidelines for the management of spontaneous pneumothorax.
Thorax 2003;58(suppl II):ii39-ii52.
- Armstrong P, Wilson AG, Dee P, Hansell DM: Imaging of
Disease of the Chest (3rd edition): p763-773.
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Case Discussion
繼續教育考題