Hamman’s syndrome is a rare condition that mostly affects young males, often with a predisposition of asthma. It includes the presence of free air in the mediastinum and subcutaneous emfysema with no other underlying cause such as trauma or infection. It occurs spontanously and often in association with prolonged valsalva manouvre. This might explain why there are some cases of Hamman syndrome among young females giving birth. Here we present a case report of a 24-year- old primigravida with Hamman’s syndrome. She presented with symptoms a few hours after an uncomplicated vaginal delivery at 40+1 pregnancy week. The symptoms resolved spontanously after a few days of observation. We also give a systemic review of reported cases since 2000 to provide overview on pathomechanism, symptoms, diagnostics, treatment and management of this condition. Hamman’s syndrome is a rare, usually benign, but potentially serious complication that can occur during the second stage of labour. Diagnostics include inquiring about typical symptoms, clinical examination and chest x-ray or CT scan. Treatment is usually conservative with oxygen, bronchodilators and pain relief. The reccurence rate is low and there is no contraindication to vaginal delivery in future pregnancies. However, it is suggested that physicians and midwives be cautious and consider low threshold for instrumental delivery or caesarean section to avoid excessive valsalva manoeuvre.

Keywords:

Subject: Medicine and Pharmacology - Obstetrics and Gynaecology

Introduction

Spontaneous pneumomediastinum (SPM) during labour is a rare event, occurring in about 1 in 100 000 deliveries. Together with subcutaneous emphysema it is called Hamman syndrome [1]. The condition was named after Louis Hamman (1877-1946), the physician who described it in several case reports from 1939 to 1945 in post partum women [2,3].

SPM is defined as the presence of free air in the mediastinum, with no underlying trauma and mostly affects young males and pregnant females. It may be associated with a pulse-synchronous crunching sound, reffered to as the «Hamman’s sign» best heard when the patient is lying in the left lateral decubitus position [4,5].

Hamman’s syndrome may occur during prolonged labor, usually in the second stage, after prolonged valsalva maneuver. Other predisposing events may be intensive coughing, retching/vomiting or physical activity [6].

The condition is usually benign and self-limiting, but in rare cases there may be complications such as significant dyspnea and chest pain, and even development of malignant pneumomediastinum, which requires surgical intervention [7]. In this paper, we report a case of Hamman’s syndrome in a 24-year-old primigravida with underlying asthma, and we are reporting on the pathomechanisme and management of this condition with regards on overview of 42 other published cases in the last two decads.

Case Presentation

A 24-year old primiparous woman, with a normal pregnancy, presented to the maternity ward in spontaneous labour, with regular uterine contractions at 40+1 weeks. She was a non-smoker and denied drinking alcohol or using illict drugs. Her body mass index was 27.1, and her past medical history was significant for depression, ADHD (Attention Deficit Hyperactivity Disorder) and childhood asthma, without need for medical treatment. There was no history of any heart condition.

In the latent phase of delivery, she recieved morphine for analgesia. The water broke spontaneously, and the amniotic fluid was discolored. The patient had normal temperature and there was no fetal tachycardia or other signs of fetal distres son CTG. The active phase of labor lasted for three hours with normal progress. After one hour of passive descent, she started pushing, and the second stage lasted for 30 minutes. It was a spontaneous vaginal delivery of a healthy baby with normal Apgar score (9-10-10) weighting 4170 g. There was a normal expulsion of the placenta, and there were normal bleeding.

Eight hours after delivery, she complained of pain in the right ear, swelling and pain in the neck, chest tightness, shortness of breath, dysphagia, odynophagia and pain in the upper thorax on the right side. Her vital signs were stable (BP 128/67 mmHg, pulse 91/min., temperature 36.0, respiratory rate 14/min., oxygen saturation 99% on room air). ECG was unremarkable. Blood gas showed normal values with pH 7.45, pCO2 4.2. PCR- test from nasopharynx was negative for viral infections. There were no findings on otoscopy. On palpation, there were subcutaneous crepitations in the neck, parasternal region, right axillary fossa, clavicle and over the chest. Auscultation of the heart and lungs was normal. A chest X-ray (Figure 1) was taken immediately, revealing subcutaneous emphysema extending bilaterally to the neck, but more prominent on the right side, and suspicious for pneumomediastinum. There were no signs of pneumothorax or esophageal or sceletal pathology. The heart configuration was normal. The patient received 1 g of paracetamol and 2.5 mg of morphine intravenously. The situation was clinicaly stable. The next day, a CT scan (Figure 2) without contrast was performed, confirming pneumomediastinum, with air extending from diaphragma up to the thoracic apeces and across larynx. There were descreet amounts of pleural fluid bilaterally, and subcutaneous emphysema from the base of the skull to the neck and upper thorax.

The patient was reviewed by the medical team (radiologist, gynecologist and surgeon), and diagnosed with Hamman`s syndrome. As the patient was hemodynamically stable, she was managed conservatively with observation and analgetics. Her symptoms resolved gradually over the next three days and she was discharged home on her third day post partum. She was advised to avoid strenous physical activity for the next four weeks. On follow up at the 6-weeks postnatal, she was in well being and completely without symptoms. Follow-up correspondance was also done over the phone at five months. The patient had recovered well, and was now practicing normal physical activity.

Discussion

Hamman’s syndrome is a rare clinical entity. Its incidence is 1:100 000 women giving birth. The incidence is higher in the case og accidents og emergencies and has a male predisposition, accounting for 76% of cases [8]. It is believed to be a result of a sudden increase in intra-alveolar pressure. Mostly it is associated with valsalva manouver, extensive vomiting, or coughing, all of which can occur in pregnancy and labour.

There have been several cases on Hamman’s syndrome occuring in labour, but it has also been reported in association with other medical conditions, such as diabetic ketoacidosis with repeated vomiting or Kussmaul breathing [9,10] and bronchial asthma, with vomiting and coughing as common precipitating factors [11,12]. There has also been reports of SPM occuring after intense coughing during strenous physical activity [13] or hyperemesis gravidarum [14].

In our case, extensive breathing during the first stage and intensive Valsalva manouver in the second stage of labour in a patient with an underlying bronchial asthma, led to the development of symptoms of Hamman’s syndrome after delivery. The CT scan of the chest was taken to exclude other severe diseases like pulmonary embolism, amniotic fluid embolism, myocardial infarction and Boerhaave syndrome.

The pathophysiology of Hamman’s syndrome is explained as follows: The intra-alveolar pressure is acutely increased during the Valsalva manoeuvre causing rupture of marginal alveoli adjacent to blood vessels. The free air moves from ruptured alveoli along peribronchial vascular sheaths towards the hilum of the lung. From there, it extends proximally and can spread within the mediastinum, pericardium, neck, subcutaneous tissue and retroperitoneum. The absence of transverse fascial planes in the mediastinum allows the unobstructed passage of air along tissue planes into the neck and around the larynx. The air may also be trapped between the parietal and visceral pleura, causing pneumothorax. The pressure of the interstitial air rarely causes respiratory compromise [1]. Coughing, vomiting, screaming and the force of pushing in labor, all together, can increase the intrathoracic pressure.

The most common symptoms are chest (retrosternal) pain radiating to the back or neck, dyspnea, and swelling of face and neck. The crepitus palpable in the face and neck is pathognomonic of the condition [4,15]. Other symptoms include change of voice (dysphonia), cough, sore throat, tachycardia, dysphagia and haemoptysis. A characteristic sign is the bubbling or crunching sounds over the heart, synchronous with the cardiac cycle known as Hamman’s sign or murmur. The occurence of the symptoms, time onset after/during delivery, severity of the condition and management can be very variable, as it is described in our summarized overview on the reported cases over the last two decades (Table 1).

In our case, the woman presented immediately after delivery with pain around the ear and the feeling of plugged ear. A few hours later she reported swelling of the neck, chest tightness and shortness of breath. On examination, the crepitus on the neck and thorax was obvious, but there was no typical Hamman’s murmur.

Hamman’s syndrome is usually a benign and non-recurrent condition, however, in rare cases it may be life threatening and lead to cardiac tamponade with significant hemodynamic compromise. Such situation require surgical intervention [16]. Prior to any intervention, it is important to exclude other serious, potentially life-threathening conditions such as esophageal rupture (cancer related), Boerhaave syndrome (rupture of the esophagus due to forceful vomiting), pharyngeal rupture, pulmonary embolism, amniotic fluid embolism, aortic dissection, myocardial infarction, pneumopericardium, or pneumothorax of any cause [17,18].

Apart from the clinical picture, a CT scan is the gold standard in diagnosing pneumomediastinum. In a systematic review, it was found that about 30% of cases of pneumomediastinum were poorly detected by chest x-ray, but were easily detected on a CT-scan [19]. The CT also provides more accurate information on the extension of subcutaneous emphysema and other thoracic pathologies. An additional tool that can be considered is diagnostic endoscopy (bronchoscopy or esophagoscopy) or esophagography [20].

Initial management is supportive treatment with oxygen, sedatives and analgetics, as needed. In severe cases, the treatment with antibiotics and bronchodilators, along with oxygen support may added. The patient should be reassured about good prognosis and expected spontaneous resolution within (3-14 days) [21]. Patients can be discharged if they are in good general condition and do not have a significant pneumothorax. There is no recommended rutine follow up.

There have been a few reports of cases with spontaneous pneumomediastinum occuring in the setting of hyperemesis gravidarum in early pregnancy [14] or spontaneously in the third trimester. Here the operative delivery should be considered to prevent worsening/recurence of this condition [22].

Conclusion

Post partum pneumomediastinum (Hammans syndrome) is a rare complication however its timely diagnosis is necessary for patient safety and management. The most cases in pregnant women occur in the second stage of labour, as a result of excessive straining and valsalva maneuver. The recurrence rate in subsequent pregnancies is low, and there are no established guidelines on the management. It is suggested that measures which can be implemented are to minimise barotrauma with the low threshold for instrumental or operative delivery, and approaches limiting the duration of the second stage of labour. However his is not evidence based and may require meta-analytical approach.

Author Contributions

KOB: original draft preparation, clinical management; MMK: retrieving clinical data, database search, clinical management; KK: methodology, conceptualization; LJR: clinical management, original draft preparation; JV: writing, review and editing; PZ: writing and original draft preparation, clinical management, conceptualization, review and editing, supervision. All authors heave read and agreed to the published version of the manuscript.

Funding

The manuscript received no funding.

Conflict of interest statement

The authors declare that there is no conflict o finterests regarding the publication of this paper.

Acknowledgements

Authors thank to Mrs. Petra Zuborova, PhD for technical help with managing this paper and to the pasient who approved the content of the paper and signed the consent for the publishing of this case.

Informed consent statement

Written informed consent was obtain from the patient. Under the all management steps and in case presentation the principles of the Helsinki Declaration were followed.

Institutional review board statement

The presented study was carried out following the rules of the Declaration of Helsinky of 1975, revised in 2013. According to local IRB principles, ethical approval from IRB for a single case is not required, as long as data are kept anonymous and subject signed informed consend with the publishing.

Data availability statement

Data sharing nor applicable to this article as no datasets were generated or analyzed during the current study. The data presented in this study are available on request.

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Figure 1. Plain radiograph scan showing typical gas accumulations seen subcutaneous and with pneumomediastinum (arrows, part A): There is significant subcutaneous emphysema, more pronounced on the right side (arrow, part A). We can see an outlining of the pericardium both in lateral projection (arrow, part B) and with «continuous diaphragm sign» on frontal projection (arrow, part A). You can also see continuous lucencies along upper mediastinum to the neck, through upper thoracic aperture.

Figure 2. Low dose CT scan showing air within the mediastinum starting caudally in the level of hiatus aorticus, surrounding the pericardium, throughout the mediastinum. In the neck level, air was seen subcutaneously (part A), along the great vessels (carotid space) and in the retropharyngeal space (part B). The patient has an «azygos lobe», a normal variant with the vena azygos running laterally with a pleural fissure surrounding it (arrow, part A). Air bubbles can be seen along the vein and small amounts of air within the pleural cavity apically on the right side. Apart from this, no signs of pneumothorax. Small amounts of pleural effusion is seen bilaterally. The upper abdomen was included in the low-dose scan, without any signs of air below the diaphragm.

Table 1. An overview on 42 previously published cases of pregnancy associated Hamman`s syndrome (database Pubmed.gov from from 2000 to 3/2024). Abbreviations: N/A - not available; IV – intravenous; h - hours.

Author	Age y/o	Parity	When symptoms developed	Duration of labour	Week of gestation	Treatment
Sutherland et al. 2002 [23]	32	Para 1	Post partum	8h	N/A	None
Sutherland et al. 2002 [23]	22	Para 1	13h post partum	N/A	N/A	None
Miguil et al. 2004 [24]	19	Para 0	N/A	N/A	40	Oxygen & analgetics, C-section
Duffy 2004 [25]	19	Para 0	2h	90 min 2^nd stage	40	Oxygen v analgetics
Bonin et al. 2006 [26]	27	Para 0	2^nd stage	6h	38	Lorazepam for anxiety & anxiolytics for dyspnea
Norzilawati et al. 2007 [27]	21	Para 0	12h post partum	4h, 100 min 2^nd stage	40	None
Yadav et al. 2008 [28]	21	Para 0	2^nd stage	2^nd stage 1,5h	N/A	Oxygen & analgesics
Mahboob et al. 2008 [29]	24	Para 0	18h post partum	N/A Normal	39	Oral antibiotics, iv fluids & analgetics
Zapardiel et al. 2009 [30]	29	Para 0	Post partum	N/A	39	Oxygen
Revicky et al. 201031	32	Para 0	3h	14h	40	None
Beynon et al. 2011 [32]	18	Para 0	8h post partum	4h	39	Antibiotics & analgetics
Wozniak et al. 2011 [33]	20	Para 0	5h post partum	9h	41	Observation
Shrestha et al. 2011 [34]	19	Para 0	N/A	N/A	36	None
Kuruba et al. 2011 [1]	32	Para 1	2^nd stage	1.5h	40	None
McGregor et al. 2011 [35]	27	Para 0	2^nd stage	7,5h	40	Oxygen & analgetics
Houari et al. 2012 [36]	21	Para 0	Post partum	N/A	40	Conservative management
Kandiah et al. 2013 [37]	25	Para 0	2^nd day post partum	2^nd stage 3h, 16 min. Ending in a C-section	40	Observation
Kandiah et al. 2013 [37]	30	Para 0	2^nd stage	6h	38	Observation
Kouki et al. 2013 [38]	23	Para 0	2^nd stage	9h	40	Oxygen & analgesics and sedatives
Khoo et al. 2015 [39]	33	Para 0	2^nd stage	12h	40	Analgetics & bed rest
Cho et al. 2015 [7]	28	Para 0	2^nd stage	5h	36	Oxygen & analgesics
Wijesuriya et al. 2015 [40]	24	Para 0	N/A	N/A	N/A	N/A
Khurram et al. 2015 [4]	24	Para 1	2h post partum	2^nd stage prolonged	40	None
Scala et al. 2016 [41]	30	N/A	2^nd stage	N/A	40	None
Elshirif et al. 2016 [42]	27	Para 0	4h post partum	19h 2^nd stage 3h	41	Analgetics, oxygen & antibiotics
Berdai et al. 2017 [43]	22	Para 0	2^nd stage	2h	40	Oxygen
Lou et al. 2017 [44]	29	Para 0	2^nd stage	Prolonged	At term	Supportive
Sagar et. al 2018 [45]	22	Para 0	3h post partum	4,5h	37	None
Khan et al. 2018 [46]	30	Para 0	N/A	N/A	N/A	Antibiotics, oxygen & bronchodilators
Jakes et al. 201947	23	Para 0	40 min post partum	2^nd stage 2h	38	Oxygen
Madhok et al. 2019 [48]	21	Para 0	2h post partum	3h	39	None
Lee et al. 2019 [49]	31	Para 0	2^nd stage	8,4h	41	IV antibiotics, hydrokortison & Loratadine
Chavan et al. 2019 [50]	33	Para 0	10h post partum	90 min 2^nd stage	38	Oxygen & analgetics
Opstelten et al. 2019 [51]	25	Para 0	2^nd stage	N/A	N/A	N/A
Oshovskyy et al. 2020 [52]	34	Para 4	2^nd stage	4,5h	39	Pigtail catheter
Badran et al. 2020 [53]	N/A	Para 0	4h post partum	N/A	Full term	Nil by mouth
Zethner-Møller et al. 2021 [54]	35	Para 1	2^nd stage	N/A	36	Oxygen
Mullins et al. 2021 [55]	17	Para 0	post partum, prolonged second stage	N/A	39	Oxygen & opioids
La Verde et al. 2022 [17]	23	Para 0	2^nd stage	5h	41	None
Gomes et al. 202 [26]	21	Para 0	2^nd stage	N/A	40	C-section & observation
Peña-Vega 2023 [56]	18	Para 0	30h post partum	12h	39	Oxygen
Chooi et al. 2023 [57]	22	Para 0	2^nd stage	3h 2^nd stage	39	None
Hülsemann et al. 2023 [58]	21	Para 0	2^nd stage	Prolonged	N/A	N/A
Inesse et al. 2023 [59]	29	Para 0	1h post partum	2^nd stage lasted 2h, 40 min active pushing	40	None
Chen et al. 2023 [60]	20	Para 0	immediately after delivery	Prolonged	43	Analgetics & antibiotics iv

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