Table 4 Prognosis of SIPE

Adir et al. [12]

Military trainees (Israeli Navy)

Unknown number of males aged 18–19 in swimming trials of 2.4–3.6 km in 1998–2001 (70 cases)

3 years but variable

Open sea of varying temperatures (19.6 °C ± 3.2), no wetsuits, supine semi-reclining position with fins

Severe shortness of breath and coughing during or after swimming in the absence of sea aspiration, and evidence of PE found on medical examination

Interview and clinical examination of swimmers presenting to medical team

No hospitalisations. All recovered from SIPE symptoms within 24 h. Chest radiographs 12–18 h after episode were all normal. A subsample of 37 trainees had restricted lung function that persisted for a week

22.9% of cases (16 trainees) had a recurrence during the study ≥ 3 months after first episode

Not reported

No control group. Only a subsample of 37 were followed up at 7 days

Shupak et al. [13]

Military trainees (Israeli Navy)

35 males (21 cases, 14 comparators) aged 18–19 performing 5 swimming trials of 2.4–3.6 km over 2 months. Trials were ≥ 1 week apart

2 months

Moderately cold open sea, (16–18 °C), diving jackets, supine position with fins

When, in the absence of prior seawater aspiration, the swimmer reported shortness of breath accompanied by coughing

Post-swim questionnaire completed by all trainees plus physical examination: oxygen saturation, changes in pulmonary function

Not reported

31% (9 out of 29 episodes observed) were recurrences of previously observed episodes

Not reported.

No follow-up

Weiler-Ravell et al. [14]

Military trainees (Israeli Navy)

30 males (8 cases, 22 comparators) aged 18–19 performing a 2.4 km swimming trial

Until end of training programme

Warm open sea (23 °C), no wetsuit, supine position with fins, over- hydration (trainees drank approx. 5 l of water prior to swimming)

Dyspnoea and haemoptysis

Clinical examination of trainees presenting to medical team

All stayed overnight in hospital and recovered within 24 h

25% of cases (2 trainees) had a recurrence later during the training programme (unknown time period)

Not reported

Only one swimming trial. Unclear when recurrences took place

Ludwig et al. [29]

Military trainees (US Navy Special Warfare)

20 males including 11 cases aged 19–36 who had completed the first 5 weeks of a 22-week long training programme

Study began 4–14 weeks after recovery from SIPE

Not reported

(1) acute onset of dyspnoea or haemoptysis during or immediately after swimming, (2) no history of water aspiration, laryngospasm, or preceding infections, (3) hypoxemia, as defined by an oxygen saturation < 92% by pulse oximetry or an alveolar-arterial oxygen gradient of > 30 mmHg and (4) radiographic opacities consistent with an alveolar filling process and/or interstitial pulmonary oedema that resolve within 48 h

Previous clinical diagnosis of a single episode of SIPE

All recovered at least 4 weeks prior to start of study

Not reported

No significant difference in cardio-pulmonary function between cases and controls 4–14 weeks following recovery from SIPE

No SIPE symptoms observed. Small sample size. No further follow-ups

Braman Eriksson et al. [15]

Outdoor swimmers (elite and amateur)

13,878 swimmers aged 12–70 (6317 males, 7561 females) in Swedish river races over 3 consecutive days, distances of 1-3 km, Approx.69 cases of SIPE reported

N/A

Moderately cold freshwater (17 °C), unknown number of swimmers wore full wetsuits

Breathing difficulties and/or cough in the absence of clinical signs of obstruction

Clinical examination of competitors presenting to medical team

All recovered following treatment on site

31% of cases (20 swimmers) self-reported having experienced respiratory difficulties whilst swimming previously

None reported

Data only collected for those requiring treatment. Symptoms and clinical findings were not recorded for each swimmer