Hiccups (AKA singultus) are due to the involuntary contraction of the inspiratory muscles, especially the diaphragm. The hiccup reflex involves an afferent limb ( eg, the phrenic and vagus nerves, sympathetic fibers from T6-T12,  brainstem) and an efferent limb, primarily the phrenic nerve^1,2.  Thus, the irritation of any part of the arc in the head, neck, chest, or abdomen may potentially lead to hiccups.

Conditions involving the chest cavity that may be associated with hiccups include lung cancer, GERD, herpetic esophagitis, myocardial ischemia, bronchitis, empyema, lung masses, pneumonia, pleuritis, and pacemaker lead injury ^1-3.

Reports of patients with PE and persistent hiccups (lasting longer than 48 h) have also appeared in the literature^1,3. Of interest, in a report involving 3 patients, 2 had submassive or “large” PE, with one displaying the classic EKG changes of S1Q3T3; the size of PE in another was not reported¹.  In another case report, PE was “not small” and involved the anterior and lateral lower lobe segments of pulmonary artery².  Although the exact mechanism of PE causing hiccups is not clear, irritation of the afferent or efferent limb of the reflex arc in the chest has been postulated.  

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References

1. Hassen GW, Singh MM, Kalantari H, et al. Persistent hiccups as a rare presenting symptom of pulmonary embolism. West J Emerg Med 202;13:479-483.
2. Durning SJ, Shaw DJ, Oliva AJ et al. Persistent hiccups as the presenting symptom of a pulmonary embolism. Chest Disease Reports 2012;2:e2.
3. Buyukhatipoglu H, Sezen Y, Yildiz A, et al. Hiccups as a sign of chronic myocardial ischemia. S Med J 2010;103: 1184-85.