Lake Louise Questionnaire Research Articles

Effects of acetazolamide and dexamethasone on cerebral hemodynamics in hypoxia

Previous attempts to detect global cerebral hemodynamic differences between those who develop headache, nausea, and fatigue following rapid exposure to hypoxia [acute mountain sickness (AMS)] and those who remain healthy have been inconclusive. In this study, we investigated the effects of two drugs known to reduce symptoms of AMS to determine if a common cerebral hemodynamic mechanism could explain the prophylactic effect within individuals. With the use of randomized, placebo-controlled, double-blind, crossover design, 20 healthy volunteers were given oral acetazolamide (250 mg), dexamethasone (4 mg), or placebo every 8 h for 24 h prior to and during a 10-h exposure to a simulated altitude of 4,875 m in a hypobaric chamber, which included 2 h of exercise at 50% of altitude-specific VO(2max). Cerebral hemodynamic parameters derived from ultrasound assessments of dynamic cerebral autoregulation and vasomotor reactivity were recorded 15 h prior to and after 9 h of hypoxia. AMS symptoms were scored using the Lake Louise Questionnaire (LLQ). It was found that both drugs prevented AMS in those who became ill on placebo (~70% decrease in LLQ), yet a common cerebral hemodynamic mechanism was not identified. Compared with placebo, acetazolamide reduced middle cerebral artery blood flow velocity (11%) and improved dynamic cerebral autoregulation after 9 h of hypoxia, but these effects appeared independent of AMS. Dexamethasone had no measureable cerebral hemodynamic effects in hypoxia. In conclusion, global cerebral hemodynamic changes resulting from hypoxia may not explain the development of AMS.

Alterations in cerebral blood flow and cerebrovascular reactivity during 14 days at 5050 m

Upon ascent to high altitude, cerebral blood flow (CBF) rises substantially before returning to sea-level values. The underlying mechanisms for these changes are unclear. We examined three hypotheses: (1) the balance of arterial blood gases upon arrival at and across 2 weeks of living at 5050 m will closely relate to changes in CBF; (2) CBF reactivity to steady-state changes in CO2 will be reduced following this 2 week acclimatisation period, and (3) reductions in CBF reactivity to CO2 will be reflected in an augmented ventilatory sensitivity to CO2. We measured arterial blood gases, middle cerebral artery blood flow velocity (MCAv, index of CBF) and ventilation () at rest and during steady-state hyperoxic hypercapnia (7% CO2) and voluntary hyperventilation (hypocapnia) at sea level and then again following 2–4, 7–9 and 12–15 days of living at 5050 m. Upon arrival at high altitude, resting MCAv was elevated (up 31 ± 31%; P < 0.01; vs. sea level), but returned to sea-level values within 7–9 days. Elevations in MCAv were strongly correlated (R2= 0.40) with the change in ratio (i.e. the collective tendency of arterial blood gases to cause CBF vasodilatation or constriction). Upon initial arrival and after 2 weeks at high altitude, cerebrovascular reactivity to hypercapnia was reduced (P < 0.05), whereas hypocapnic reactivity was enhanced (P < 0.05 vs. sea level). Ventilatory response to hypercapnia was elevated at days 2–4 (P < 0.05 vs. sea level, 4.01 ± 2.98 vs. 2.09 ± 1.32 l min−1 mmHg−1). These findings indicate that: (1) the balance of arterial blood gases accounts for a large part of the observed variability (∼40%) leading to changes in CBF at high altitude; (2) cerebrovascular reactivity to hypercapnia and hypocapnia is differentially affected by high-altitude exposure and remains distorted during partial acclimatisation, and (3) alterations in cerebrovascular reactivity to CO2 may also affect ventilatory sensitivity.

Prediction of Acute Mountain Sickness by Monitoring Arterial Oxygen Saturation During Ascent

Acute mountain sickness (AMS) is a common problem while ascending at high altitude. AMS may progress rapidly to fatal results if the acclimatization process fails or symptoms are neglected and the ascent continues. Extensively reduced arterial oxygen saturation at rest (R-Spo₂) has been proposed as an indicator of inadequate acclimatization and impending AMS. We hypothesized that climbers less likely to develop AMS on further ascent would have higher Spo₂ immediately after exercise (Ex-Spo₂) at high altitudes than their counterparts and that these postexercise measurements would provide additional value for resting measurements to plan safe ascent. The study was conducted during eight expeditions with 83 ascents. We measured R-Spo₂ and Ex-Spo₂ after moderate daily exercise [50 m walking, target heart rate (HR) 150 bpm] at altitudes of 2400 to 5300 m during ascent. The Lake Louise Questionnaire was used in the diagnosis of AMS. Ex-Spo₂ was lower at all altitudes among those climbers suffering from AMS during the expeditions than among those climbers who did not get AMS at any altitude during the expeditions. Reduced R-Spo₂ and Ex-Spo₂ measured at altitudes of 3500 and 4300 m seem to predict impending AMS at altitudes of 4300 m (p < 0.05 and p < 0.01) and 5300 m (both p < 0.01). Elevated resting HR did not predict impending AMS at these altitudes. Better aerobic capacity, younger age, and higher body mass index (BMI) were also associated with AMS (all p < 0.01). In conclusion, those climbers who successfully maintain their oxygen saturation at rest, especially during exercise, most likely do not develop AMS. The results suggest that daily evaluation of Spo₂ during ascent both at rest and during exercise can help to identify a population that does well at altitude.

Non‐invasive positive pressure ventilation during sleep at 3800 m: Relationship to acute mountain sickness and sleeping oxyhaemoglobin saturation

Overnight oxyhaemoglobin desaturation is related to AMS. AMS can be debilitating and may require descent. Positive pressure ventilation during sleep at high altitude may prevent AMS and therefore be useful in people travelling to high altitude, who are known to suffer from AMS. Ascent to high altitude results in hypobaric hypoxia and some individuals will develop acute mountain sickness (AMS), which has been shown to be associated with low oxyhaemoglobin saturation during sleep. Previous research has shown that positive end-expiratory pressure by use of expiratory valves in a face mask while awake results in a reduction in AMS symptoms and higher oxyhaemoglobin saturation. We aimed to determine whether positive pressure ventilation would prevent AMS by increasing oxygenation during sleep. We compared sleeping oxyhaemoglobin saturation and the incidence and severity of AMS in seven subjects sleeping for two consecutive nights at 3800 m above sea level using either non-invasive positive pressure ventilation that delivered positive inspiratory and expiratory airway pressure via a face mask, or sleeping without assisted ventilation. The presence and severity of AMS were assessed by administration of the Lake Louise questionnaire. We found significant increases in the mean and minimum sleeping oxyhaemoglobin saturation and decreases in AMS symptoms in subjects who used positive pressure ventilation during sleep. Mean and minimum sleeping SaO2 was lower in subjects who developed AMS after the night spent without positive pressure ventilation. The use of positive pressure ventilation during sleep at 3800 m significantly increased the sleeping oxygen saturation; we suggest that the marked reduction in symptoms of AMS is due to this higher sleeping SaO2. We agree with the findings from previous studies that the development of AMS is associated with a lower sleeping oxygen saturation.

Incidence of Acute Mountain Sickness in Adolescents

To measure the incidence of acute mountain sickness (AMS) in adolescents travelling to moderately high altitudes. The study was carried out on a cohort of 63 adolescents with an average age of 15.9 years during an 8-day trip to Morocco, travelling to altitudes between 3106 m and 4167 m. The incidence of AMS was calculated using the Lake Louise questionnaire, which was completed twice daily by each participant. An episode of AMS was defined as being a score of 3 or more on the Lake Louise questionnaire in the presence of a headache. Difference in incidence between boys and girls was analyzed using 2-tailed Mann-Whitney U testing. The daily incidence of AMS among 52 participants with complete data was found to be between 3.8% and 42.3% and increased with increasing altitude. Girls had a statistically significant higher incidence of AMS (80%) compared with boys (55%) (P < .01). Acute mountain sickness may occur more commonly in female adolescents than in male adolescents. Overall, however, it appears that the incidence of AMS in adolescents is similar to that found in adults in previous studies.

Hydration and the Physiological Responses to Acute Normobaric Hypoxia

The effect hydration status has on exposure to hypoxia is unclear. The purpose of the study was to identify how hydration status, above and below euhydrated levels, affects the physiological responses and onset of acute mountain sickness symptoms during acute normobaric hypoxia. Eight males completed intermittent walking tests under normobaric hypoxic conditions (FIo2 = 0.13) after controlled hyperhydration, hypohydration, and euhydration protocols. A range of physiological, psychological, and altitude illness markers were monitored throughout the 125-minute exposure. Heart rate, core temperature, peripheral arterial oxygen saturation, urine osmolality, and mean self-reported Lake Louise Questionnaire acute mountain sickness scores were significantly different between euhydration, hypohydration, and hyperhydration, respectively, and closely correlated with environmental symptoms questionnaire, Lake Louise questionnaire, and headache scores (P < .05). Other measures of ventilation and lung function were also significantly different between hydration conditions (P < .05). Hydration state above and below euhydration has detrimental consequences on physiological strain and onset of acute mountain sickness symptoms when exposed to acute normobaric hypoxia.

The effect of hypohydration severity on the physiological, psychological and renal hormonal responses to hypoxic exercise

Evidence of the effect of dehydration on physiological responses to hypoxia is limited. The purpose of this study was to determine the effect of hypohydration severity on physiological, renal hormonal and psychological responses to acute hypoxia. Eight males completed intermittent walking tests under normobaric hypoxic conditions (FI O(2) = 0.13) after completing four separate hypohydration protocols, causing change in body mass of approximately 0% (EU), -1% (H1), -2% (H2) and -3% (H3). Physiological and psychological markers were monitored throughout the 125 min test. Fluid controlling hormones were measured pre and post exposure. Heart rate, core temperature, peripheral arterial oxygen saturation (SpO(2)), minute ventilation and urine osmolality were found to be significantly different between hydration conditions and correlated with Lake Louise Questionnaire score (LLQ) (P < 0.05). LLQ score increased with hypohydration severity above H2 (EU 1.3 +/- 1; H1 1.2 +/- 1; H2 2.7 +/- 2; H3 3.9 +/- 2) (P < 0.001). Antidiuretic hormone and aldosterone increased over the test, but were not different between hydration conditions (P < 0.05). Atrial natriuretic peptide showed no change over time, or with conditions. Therefore, renal hormones are not influenced by hypohydration severity during moderate intensity hypoxic exercise. Hypohydration less than -2% induces greater physiological strain during hypoxic exercise and may cause rise in symptoms such as, fatigue, headache, nausea and lightheadedness.

Prevalence of Acute Mountain Sickness among Finnish Trekkers on Mount Kilimanjaro, Tanzania: An Observational Study

The aim of this study was to evaluate the prevalence of acute mountain sickness (AMS) among trekkers on Mount Kilimanjaro during the winter season of 2006-2007. A A total of 130 Finnish trekkers at Marungu route were asked to complete daily a Lake Louise self-report and clinical assessment score questionnaire with the help of a trainee Finnish guide during their trek to Kilimanjaro. A Lake Louise questionnaire score>or=3 indicated AMS. Altogether 112 mountaineers or travelers [54 men, 58 women, mean age 51+/-10 (SD) years] were studied. Fifty-nine travelers (53%) reached Gillman's Point or Uhuru Peak. The incidence of AMS among Finnish Kilimanjaro trekkers was 75%. The most common high altitude symptoms were headache, followed by sleeping problems and fatigue or weakness. The incidence of AMS is high among trekkers climbing Mount Kilimanjaro.The main reason for this seems to be rapid ascent. Kilimanjaro treks normally have a fixed timetable, and for commercial reasons there is little opportunity to spend extra days for acclimatization in the camps. Some contributing factors are preventable, so we recommend an educational program for all the trekking agencies that guide on this peak and, in particular, the Tanzania-based guiding agencies, which, typically, are driving these very fast ascent rates.

EEG, ECG and oxygen concentration changes from sea level to a simulated altitude of 4000m and back to sea level

In order to describe how high altitude affects the body during a one night stay at 4000m experiments were performed in a hypobaric chamber and compared to a study on Dachstein (mountain in Austria, 2700m). Ten subjects had to perform a reaction time task at different altitudes. The EEG and ECG were recorded simultaneously. Additionally, the oxygen saturation of the blood was measured at different altitudes and the subjects filled out a Lake Louise questionnaire that describes the degree of altitude mountain sickness (AMS). After elevation from 134m to 4000m in the hypobaric chamber heart-rate increased from 68.9bpm to 81.6bpm, RMSSD (root mean square of squared differences of adjacent heart beat intervals) decreased from 54.3ms to 33.3ms, the LF/HF ratio increased from 2.5 to 3.9 and oxygen saturation decreased to 82.7% after 11h at 4000m altitude. The Lake Louise Score (LSS) reached 3.4 after one night at 4000m. EEG beta activity between 14Hz and 18Hz was attenuated at 4000m and also after return to 134m. The results indicate that the subjects were not able to adapt to 4000m within 12h in the hypobaric chamber. Even after 1h after the return to 134m all parameters are still affected from the night at 4000m altitude. ECG and EEG changes are in line with results obtained at 2700m height at Dachstein.

Physiological Responses to Graded Acute Normobaric Hypoxia Using an Intermittent Walking Protocol

The study aimed to examine the physiological responses to acute normobaric hypoxia during an intermittent walking protocol. Twelve active healthy male participants completed a 125-minute test that involved rest and walking (50% VO(2max)) during normoxic (20.93%O(2)) and 2 hypoxic conditions (14%O(2) and 12%O(2)). A range of physiological markers were measured throughout the test. Lake Louise Questionnaire scores and Environmental Symptoms Questionnaire cerebral scores were used as a measurement of acute mountain sickness symptoms. Oxygen saturation, thermal sensation scale, heart rate, perceived thirst, core temperature, rating of perceived exertion, feeling state, and Deltabody mass all positively correlated with the highest Lake Louise Questionnaire and Environmental Symptoms Questionnaire cerebral scores (P < .05) and were significantly different between the 3 conditions during the exercise phases. A range of physiological markers are associated with symptoms of acute mountain sickness following brief periods of hypoxic exposure.

Ginkgo biloba Decreases Acute Mountain Sickness in People Ascending to High Altitude at Ollagüe (3696 m) in Northern Chile

To determine the prophylactic effect of Ginkgo biloba (doses 80 mg/12 h, 24 h before high-altitude ascension and with continued treatment) in preventing acute mountain sickness (AMS) at 3696 m in participants without high-altitude experience. Thirty-six participants who reside at sea level were transported to an altitude of 3696 m (Ollagüe). The participants were divided into 3 groups and received G biloba (n=12) 80 mg/12 h, acetazolamide (n=12) 250 mg/12 h, or placebo (n=12) 24 hours before ascending and during their 3-day stay at high altitude. The Lake Louise Questionnaire constituted the primary outcome measurement at sea level and at 3696 m. A Lake Louise Self-Report Score greater than 3 was indicative of AMS. Oxygen saturation, heart rate, and arterial pressure were taken with each evaluation for AMS. A significant reduction in AMS was observed in the group that received G biloba (0%, P<.05) comparison with the groups receiving acetazolamide (36%, P<.05) or placebo (54%). No difference was observed in arterial oxygen saturation in the G biloba (92+/-2) vs the acetazolamide (89+/-2) groups. However, a marked increased saturation in arterial oxygen was seen in comparison with the placebo group (84+/-3, P<.05). No statistically significant differences were observed in mean arterial pressure or heart rate. This study provides evidence supporting the use of G biloba in the prevention of AMS, demonstrating that 24 hours of pretreatment with G biloba and subsequent maintenance during exposure to high altitude are sufficient to reduce the incidence of AMS in participants with no previous high-altitude experience.

Comparing Questionnaires for the Assessment of Acute Mountain Sickness

Exposure to high altitude in nonacclimatized subjects may lead to acute mountain sickness (AMS). AMS is a syndrome characterized by headache accompanied by one or more other symptoms, such as light-headedness, dizziness, loss of appetite, nausea, vomiting, fatigue, lassitude, and trouble sleeping. Assessing the presence and degree of AMS can be done using self-administered questionnaires like the Lake Louise Questionnaire (LLQ) and the Environmental Symptoms Questionnaire-III (ESQ-III). We compared LLQ and ESQ-III in 266 trekkers of different nationalities trekking over a 5400-m-high pass to assess if the two questionnaires identify the same population as suffering from AMS and to see whether using English questionnaires poses problems for nonnative English-speaking persons. The use of English questionnaires by nonnative English speakers influenced the outcome for some nationalities. For criterion scores yielding similar prevalence of AMS, ESQ-III labeled 20% of cases differently (AMS or no AMS) when compared to LLQ. Correlations between similar individual questions of ESQ-III and LLQ were variable, and there was considerable scatter between ESQ-III and LLQ scores. In conclusion, English questionnaires may pose problems in some international settings, and ESQ-III and LLQ may identify different populations as suffering from AMS.

Normo or hypobaric hypoxic tests: propositions for the determination of the individual susceptibility to altitude illnesses

Assessment of individual susceptibility to altitude illnesses and more particularly to acute mountain sickness (AMS) by means of tests performed in normobaric hypoxia (NH) or in hypobaric hypoxia (HH) is still debated. Eighteen subjects were submitted to HH and NH tests (PIO2=120 hPa, 30 min) before an expedition. Maximal and mean acute mountain sickness scores (AMSmax and mean) were determined using the self-report Lake Louise questionnaire scored daily. Cardio-ventilatory (f, V(T), PetO2 and PetCO2, HR and finger pulse oxymetry SpO2) were measured at times 5 and 30 min of the tests. Arterial (PaO2, PaCO2, pH, SaO2) and capillary haemoglobin (Hb) measurements were performed at times 30 min. Hypoxic ventilatory (HVR) and cardiac (HCR) responses, peripheral O2 blood content (CpO2) were calculated. A significant time effect is found for DeltaSpO2 (P = 0.04). Lower PaCO2 (P = 0.005), SaO2 (P = 0.07) and higher pH (P = 0.02) are observed in HH compared to NH. AMSmax varied from 3 to12 and AMSmean between 0.6 and 3.5. In NH at 30 min, AMSmax is related to PetO2 (R = 0.61, P = 0.03), CpO2 (R = -0.53, P = 0.02) and in HH to CpO2 (R = -0.57, P = 0.01). In NH, AMSmean is related to Deltaf (R = 0.46, P = 0.05), HCR (R = 0.49, P = 0.04), CpO2 (R = -0.51, P = 0.03) and, in HH at 30 min, to V(T) (R = 0.69, P = 0.01) and a tendency for CpO2 (R = -0.43, P = 0.07). We conclude that HH and NH tests are physiologically different and they must last 30 min. CpO2 is an important variable to predict AMS. For practical considerations, NH test is proposed to quantify AMS individual susceptibility using the formulas: AMSmax = 9.47 + 0.104PetO2(hPa)-0.68CpO2 (%), (R = 0.77, P = 0.001); and AMSmean = 3.91 + 0.059Deltaf + 0.438HCR-0.135CpO2 (R = 0.71, P = 0.017).

Self-Assessment of Acute Mountain Sickness in Adolescents: A Pilot Study☆

To perform a pilot study exploring the prevalence of acute mountain sickness (AMS) in adolescents on ascent to altitude and evaluating whether this age group is capable of self-assessment of AMS using the Lake Louise scoring system. Twelve teenagers aged 15 to 18 years old (5 girls) traveled for 21 days between 2400 and 5500 m. Each member of the expedition completed a Lake Louise self-assessment questionnaire on a daily basis. Group leaders (nonmedical) were informed about any subject with a score of 3 or more. Appropriate treatments were then initiated. Detailed analysis of data was undertaken on return to the UK. There was 100% completion of 252 questionnaires. Eleven of the 12 subjects (91.7%) had symptom scores greater than or equal to 3, consistent with a diagnosis of AMS, on at least one day (range, 0-8). Symptoms of AMS were more common in the female group members (P = .041). AMS is a common problem among adolescents. There are increasing numbers of adolescents traveling to high altitudes, and there appears to be a lack of information about the prevalence of AMS in this age group. Motivated adolescents seemed capable of self-monitoring for AMS using the Lake Louise questionnaire. Combined with an appropriate ascent profile and support, we feel this approach may contribute to safety in the mountains and merits further study.

ANTIOXIDANT SUPPLEMENTATION DOES NOT REDUCE INCIDENCE OR SEVERITY OF ACUTE MOUNTAIN SICKNESS AT 4300 M

The pathophysiology of acute mountain sickness (AMS) may be related to oxidative stress raising the possibility that antioxidants represent an alternate therapy for AMS. PURPOSE To test the hypothesis that antioxidant supplementation would decrease the incidence and severity of AMS during two weeks of elevated energy expenditure and caloric deficit at 4300 m. METHODS Eighteen trained males (25 ± 1 yr, mean ± SE) completed the Environmental Symptoms Questionnaire III (ESQ) and Lake Louise Questionnaire (LLQ) at sea level (SL) and daily during two weeks at high altitude (HA) (4300 m). During both SL and HA testing subjects were provided with a low antioxidant diet that maintained caloric balance at SL. However, while at HA energy expenditure was increased to achieve a caloric deficit of ∼1500 kcal·d−1. Following SL testing subjects were divided into two groups matched for ventilatory chemosensitivity, VO2peak, body mass, body composition, and age. In double blind fashion the two groups were assigned to either the placebo (PL) or antioxidant (AO) group and began supplementation three weeks prior to going to HA. RESULTS There were no significant differences in AMS incidence or severity between PL and AO on any day. The incidence of AMS as measured by the ESQ AMS- Cerebral factor score (AMS-C) peaked on day 1 of HA with 13 of 18 subjects reaching the criterion score. The AMS-C score was significantly elevated above SL on days 1–4 of HA (SL 0.156 ± 0.051 vs. HA1–4 0.964 ± 0.321, P < 0.05). These results were confirmed with the analysis of the ESQ AMS-Respiratory factor score and LLQ data. CONCLUSIONS Antioxidant supplementation does not reduce the incidence or severity of AMS during two weeks of elevated energy expenditure and caloric deficit at 4300 m. Supported by the Departments of Veterans Affairs and Defense

Acute Mountain Sickness in Tourists with Children at Lake Chungará (4400 m) in Northern Chile

To evaluate the presence of acute mountain sickness (AMS) and cardiorespiratory responses in adult and pediatric tourists exposed to high altitude (Putre and Chungará). The study was performed during a tourist expedition to Lake Chungará (4400 m) with an overnight stay in the town of Putre (3500 m). The study group included 15 adults (21-44 years), 10 teenagers (13-18 years), and 6 children (6-48 months). We evaluated AMS symptoms in adults with the Lake Louise questionnaire and in children with the modified Children's Lake Louise Score for preverbal subjects. Cardiorespiratory measurements included heart rate and oxygen saturation on arrival at Putre and Chungará. Values were expressed as mean +/- SD; significance was tested by analysis of variance, followed by the Newman-Keuls test (P < .05). Significantly lower hemoglobin saturation was found among the children in Putre (74.8% +/- 5.2%) and Chungará (65.3%+/-1.3%) than among the teenagers (82.2%+/-3.2% and 78.6% 2.5%) and adults (83.9%+/-3.3% and 79.7%+/-5.5%) at a similar altitude. A higher incidence of AMS was observed in children (100%) in Putre than in teenagers (50%) and adults (27%). Our results indicate that children are extremely sensitive to hypoxia, as expressed by symptoms of AMS and significant desaturation. Our findings add to the available information regarding the problems encountered when ascending to high altitude with children and support the importance of close monitoring of young children during ascent to high altitude.