Table 3.
Airway conditions and repeated sauna therapy.
| Study characteristics | Study sample | Intervention | Comparators | Health effects | Adverse side effects | |||||
|---|---|---|---|---|---|---|---|---|---|---|
| Author & year | Level of evidence | Design | Pop/ country |
N | Sauna type |
Duration | Comparator/ control |
Outcome measures |
Positive/negative/ negligible |
None/mild/ moderate/ severe |
| 2013- Kunbootsri et al. [57] |
I | RCT | Allergic Rhinitis/ Thailand |
26 | Thai/Finnish | 6 weeks | Control group received education and usual medical care | HRV, peak nasal inspiratory flow and usual spirometry parameters |
Positive, reduced high-freq component (p = 0.003), increased low-freq component (p = 0.003), increased low freq: high freq ratio (p = 0.003) in HRV analysis; peak nasal inspiratory flow improved (119.2 L/s ± 46.4 to 161.9 L/s ± 46.7, p = 0.002); FEV1 (forced expiratory volume at 1 sec) improved (77.5% ± 9.8% to 95.6% ± 5.7%, p = 0.002) in sauna group compared with control group. |
None |
|
| ||||||||||
| 2010- Pach et al. [58] |
I | RCT – Single blinded |
Coryza/ common cold symptoms/ Germany |
157 | Finnish | 3 days | Face mask breathing hot dry air at 90°C, 20% RH in treatment group; Face mask breathing cool, dry air at 24°C, 20% RH in control group. | Symptom severity scoring (0–10) on four different days; intake of common cold medications daily during week of intervention. |
Negligible, on day 2 only, significant decrease in symptom severity in treatment vs control group [−1.0 (−2.0–−0.1), p = 0.04, 95% CI] but was not sustained through day 3, 5, 7 assessments. Less cold medication taken on day 1 only [3% (1–9%) vs 15% (8–28%)] in treatment vs control group (p = 0.01, 95% CI). |
Mild, cough directly stimulated by face mask in both groups (2 in treatment group; 1 in control group). |
|
| ||||||||||
| 2014- Kikuchi et al. [59] |
II | Controlled intervention trial | COPD/ Japan |
20 | FIR | 4 weeks | Control group received usual medical care | Spirometry parameters; 6 MWT (6-minute walk test); modified Borg dyspnea scale; oxygen saturation; PR |
Positive, between-group improvements in FEF50 (forced expiratory flow after 50% of expired forced vital capacity) in sauna group [+0.08 L/s (0.01–0.212 L/s)] vs control group [−0.01 L/s (−0.075–0.04 L/s)], p = 0.019. |
None |
|
| ||||||||||
| 2008- Umehara et al. [60] |
III | Single group intervention, pilot study | Male COPD Ex-smokers/ Japan |
13 | FIR | 4 weeks | No control group | BP, PR, body wt, body temp; usual ECHO parameters; exercise tolerance by bicycle ergometer; SGRQ (St. George's Respiratory Questionnaire) symptom scores; plasma BNP, HCT, albumin before/after treatment. |
Positive, decreased SBP and DBP (p = 0.002–0.0002); improvements in RV function via increased pressure differential (p = 0.024); Pulmonary artery pressure during exercise decreased (p = 0.028); increased exercise time (360 s ± 107 s to 392 s ± 97 s, p = 0.032); lowest SpO2 during exercise increased (p = 0.022); symptom scores improved (59.7 pts ± 16.9 to 55.3 pts ± 17.2 pts, p = 0.002) after sauna. |
None |
COPD = chronic obstructive pulmonary disease; FIR = far-infrared sauna; PR = pulse rate; HR = heart rate; BP = blood pressure; SBP = systolic blood pressure; DBP = diastolic blood pressure; wt = weight; temp = body temperature; HRV = heart rate variability; freq = frequency; RH = relative humidity; ECHO = echocardiogram; BNP = B-natriuretic peptide; E/LFTs = electrolytes with liver function tests.