Though usually a benign and self-limited annoyance, hiccups may be persistent and a sign of serious underlying illness. In patients on mechanical ventilation, hiccups can trigger a full respiratory cycle and result in respiratory alkalosis.
Causes of benign, self-limited hiccups include gastric distention (carbonated beverages, air swallowing, overeating), sudden temperature changes (hot then cold liquids, hot then cold shower), alcohol ingestion, and states of heightened emotion (excitement, stress, laughing). There are over 100 causes of recurrent or persistent hiccups due to GI, CNS, cardiovascular, and thoracic disorders. Persistent hiccups may be an atypical presentation of COVID-19. Causes can be grouped into the following categories:
CNS: Neoplasms, infections, cerebrovascular accident, trauma.
Metabolic: Uremia, hypocapnia (hyperventilation).
Irritation of the vagus or phrenic nerve: (1) Head, neck: Foreign body in ear, goiter, neoplasms. (2) Thorax: Pneumonia, empyema, neoplasms, MI, pericarditis, aneurysm, esophageal obstruction, reflux esophagitis. (3) Abdomen: Subphrenic abscess, hepatomegaly, hepatitis, cholecystitis, gastric distention, gastric neoplasm, pancreatitis, or pancreatic malignancy.
Evaluation of the patient with persistent hiccups should include a detailed neurologic examination, serum creatinine, liver chemistry tests, and a chest radiograph. When the cause remains unclear, CT; MRI of the head, chest, and abdomen; upper endoscopy; and echocardiography may help.
A number of simple remedies may be helpful in patients with acute benign hiccups. (1) Irritation of the nasopharynx by tongue traction, lifting the uvula with a spoon, catheter stimulation of the nasopharynx, or eating 1 teaspoon (tsp) (7 g) of dry granulated sugar. (2) Interruption of the respiratory cycle by breath holding, Valsalva maneuver, sneezing, gasping (fright stimulus), or rebreathing into a bag. (3) Stimulation of the vagus by carotid massage. (4) Irritation of the diaphragm by holding knees to chest or by continuous positive airway pressure during mechanical ventilation. (5) Relief of gastric distention by belching or insertion of a nasogastric tube.
A number of drugs have been promoted as being useful in the treatment of hiccups. Chlorpromazine, 25–50 mg orally or intramuscularly, is most commonly used. Other agents reported to be effective include anticonvulsants (phenytoin, carbamazepine), benzodiazepines (lorazepam, diazepam), metoclopramide, baclofen, and gabapentin. For severe, intractable hiccups, phrenic nerve block, vagal nerve stimulation and, occasionally, general anesthesia have been used with variable efficacy.
E. A systematic review of the effectiveness of oral baclofen in the management of hiccups in adult palliative care patients. J Pain Palliat Care Pharmacother. 2020;34:43.
et al. Persistent hiccups as an atypical presenting complaint of COVID-19. Am J Emerg Med. 2020;38:1546.