The effect of temperature reduction on respiratory rate in febrile illnesses

Assembling a global database of child pneumonia studies to inform WHO pneumonia management algorithm: Methodology and applications

Background

The existing World Health Organization (WHO) pneumonia case management guidelines rely on clinical symptoms and signs for identifying, classifying, and treating pneumonia in children up to 5 years old. We aimed to collate an individual patient-level data set from large, high-quality pre-existing studies on pneumonia in children to identify a set of signs and symptoms with greater validity in the diagnosis, prognosis, and possible treatment of childhood pneumonia for the improvement of current pneumonia case management guidelines.

Methods

Using data from a published systematic review and expert knowledge, we identified studies meeting our eligibility criteria and invited investigators to share individual-level patient data. We collected data on demographic information, general medical history, and current illness episode, including history, clinical presentation, chest radiograph findings when available, treatment, and outcome. Data were gathered separately from hospital-based and community-based cases. We performed a narrative synthesis to describe the final data set.

Results

Forty-one separate data sets were included in the Pneumonia Research Partnership to Assess WHO Recommendations (PREPARE) database, 26 of which were hospital-based and 15 were community-based. The PREPARE database includes 285 839 children with pneumonia (244 323 in the hospital and 41 516 in the community), with detailed descriptions of clinical presentation, clinical progression, and outcome. Of 9185 pneumonia-related deaths, 6836 (74%) occurred in children <1 year of age and 1317 (14%) in children aged 1-2 years. Of the 285 839 episodes, 280 998 occurred in children 0-59 months old, of which 129 584 (46%) were 2-11 months of age and 152 730 (54%) were males.

Conclusions

This data set could identify an improved specific, sensitive set of criteria for diagnosing clinical pneumonia and help identify sick children in need of referral to a higher level of care or a change of therapy. Field studies could be designed based on insights from PREPARE analyses to validate a potential revised pneumonia algorithm. The PREPARE methodology can also act as a model for disease database assembly.

Stress Hyperglycemia as Predictive Factor of Recurrence in Children with Febrile Seizures

Stress hyperglycemia and hyperlactatemia are commonly referred to as markers of stress severity and poor outcome in children with severe acute illness or febrile seizures. Our prospective study aimed to explore the risk factors for stress hyperglycemia and the predictive value of stress hyperglycemia for febrile seizure recurrence. We evaluated as risk factors for blood glucose level, serum lactate, acid–base status, and the clinical parameters relevant to the severity of the infectious context or to febrile seizure event: fever degree, fever duration, seizure type and aspect, seizure duration, and recurrence. Among 166 febrile seizures events in 128 children, the prevalence of stress hyperglycemia (blood glucose >140 mg/dl) was 16.9%. The comparison of the stress versus non-stress hyperglycemia groups revealed lower pH (median (interquartile range): 7.46 (7.37, 7.53) vs. 7.48 (7.42, 7.53), p = 0.049), higher lactate levels (30.50 mg/dl (15, 36) vs. 19.50 mg/dl (15, 27), p = 0.000), slightly lower HCO₃ (20.15 (20.20, 21.45) vs. 21.35 (20, 22.40), p = 0.020) in the stress hyperglycemia group. Multiple logistic regression analysis showed that prolonged febrile seizures (>15 min), recurrent febrile seizure (>1 seizure), focal seizure type, body temperature ≥39.5 °C and higher lactate values were significantly associated with stress hyperglycemia. These findings suggest a particular acute stress reaction in febrile seizures, with stress hyperglycemia playing an important role, particularly in patients with a recurrent seizure pattern. A more complex future approach linking pathogenic mechanisms and genetic traits would be advised and could provide further clues regarding recurrence pattern and individualized treatment.

Association of Hypocapnia in Children with Febrile Seizures

Introduction:

Febrile seizure is a benign condition in children. Susceptibility genes associated with febrile convulsions have been identified, but the precise pathophysiologic mechanism that triggers febrile seizure is unclear. Using animal models, it has been demonstrated that hyperthermia causes respiratory alkalosis with consequent brain alkalosis and seizures. This study was conducted to find out any association of febrile seizures with fever induced hypocapnia.

Methods:

We conducted a cross sectional observational study and enrolled 45 children presenting with febrile seizures. Axillary temperature was measured and venous blood gas analysis was done soon after admission and within 24 hour of seizure onset. Mean pH and pCO2 from venous blood gas analysis was measured and compared with standard normal values. Data was analyzed using SPSS software version 17.0 software.

Results:

The mean pCO2 (27.95 ± 5.31mmHg) was much below normal range, and 91% of children had hypocapnia (pCO2 <35) after the febrile seizures. However alkalosis (pH > 7.45) was demonstrated in only 20% of children. Also pCO2 levels in samples drawn before 2 hours were significantly less than those taken after 2 hours (23.24 ± 3.44 vs 29.29 ± 4.99 respectively; p = 0.001).

Conclusion:

Our data indicates that febrile seizures may be associated with fever induced hyperventilation and ensuing hypocapnia may be one of the precipitating factor in inducing seizures. However, well-structured human trials are needed to demonstrate the same.

Impact of the introduction of pneumococcal conjugate vaccination on pneumonia in The Gambia: population-based surveillance and case-control studies

BACKGROUND

Pneumococcal conjugate vaccines (PCVs) are used in many low-income countries but their impact on the incidence of pneumonia is unclear. The Gambia introduced PCV7 in August, 2009, and PCV13 in May, 2011. We aimed to measure the impact of the introduction of these vaccines on pneumonia incidence.

METHODS

We did population-based surveillance and case-control studies. The primary endpoint was WHO-defined radiological pneumonia with pulmonary consolidation. Population-based surveillance was for suspected pneumonia in children aged 2-59 months (minimum age 3 months in the case-control study) between May 12, 2008, and Dec 31, 2015. Surveillance for the impact study was limited to the Basse Health and Demographic Surveillance System (BHDSS), whereas surveillance for the case-control study included both the BHDSS and Fuladu West Health and Demographic Surveillance System. Nurses screened all outpatients and inpatients at all health facilities in the surveillance area using standardised criteria for referral to clinicians in Basse and Bansang. These clinicians recorded clinical findings and applied standardised criteria to identify patients with suspected pneumonia. We compared the incidence of pneumonia during the baseline period (May 12, 2008, to May 11, 2010) and the PCV13 period (Jan 1, 2014, to Dec 31, 2015). We also investigated the effectiveness of PCV13 using case-control methods between Sept 12, 2011, and Sept 31, 2014. Controls were aged 90 days or older, and were eligible to have received at least one dose of PCV13; cases had the same eligibility criteria with the addition of having WHO-defined radiological pneumonia.

FINDINGS

We investigated 18 833 children with clinical pneumonia and identified 2156 cases of radiological pneumonia. Among children aged 2-11 months, the incidence of radiological pneumonia fell from 21·0 cases per 1000 person-years in the baseline period to 16·2 cases per 1000 person-years (23% decline, 95% CI 7-36) in 2014-15. In the 12-23 month age group, radiological pneumonia decreased from 15·3 to 10·9 cases per 1000 person-years (29% decline, 12-42). In children aged 2-4 years, incidence fell from 5·2 to 4·1 cases per 1000 person-years (22% decline, 1-39). Incidence of all clinical pneumonia increased by 4% (-1 to 8), but hospitalised cases declined by 8% (3-13). Pneumococcal pneumonia declined from 2·9 to 1·2 cases per 1000 person-years (58% decline, 22-77) in children aged 2-11 months and from 2·6 to 0·7 cases per 1000 person-years (75% decline, 47-88) in children aged 12-23 months. Hypoxic pneumonia fell from 13·1 to 5·7 cases per 1000 person-years (57% decline, 42-67) in children aged 2-11 months and from 6·8 to 1·9 cases per 1000 person-years (72% decline, 58-82) in children aged 12-23 months. In the case-control study, the best estimate of the effectiveness of three doses of PCV13 against radiological pneumonia was an adjusted odds ratio of 0·57 (0·30-1·08) in children aged 3-11 months and vaccine effectiveness increased with greater numbers of doses (p=0·026). The analysis in children aged 12 months and older was underpowered because there were few unvaccinated cases and controls.

INTERPRETATION

The introduction of PCV in The Gambia was associated with a moderate impact on the incidence of radiological pneumonia, a small reduction in cases of hospitalised pneumonia, and substantial reductions of pneumococcal and hypoxic pneumonia in young children. Low-income countries that introduce PCV13 with reasonable coverage can expect modest reductions in hospitalised cases of pneumonia and a marked impact on the incidence of severe childhood pneumonia.

FUNDING

GAVI's Pneumococcal vaccines Accelerated Development and Introduction Plan, Bill & Melinda Gates Foundation, and UK Medical Research Council.

Pediatric Patients Discharged from the Emergency Department with Abnormal Vital Signs

INTRODUCTION

Children often present to the emergency department (ED) with minor conditions such as fever and have persistently abnormal vital signs. We hypothesized that a significant portion of children discharged from the ED would have abnormal vital signs and that those discharged with abnormal vital signs would experience very few adverse events.

METHODS

We performed a retrospective chart review encompassing a 44-month period of all pediatric patients (aged two months to 17 years) who were discharged from the ED with an abnormal pulse rate, respiratory rate, temperature, or oxygen saturation. We used a local quality assurance database to identify pre-defined adverse events after discharge in this population. Our primary aim was to determine the proportion of children discharged with abnormal vital signs and the frequency and nature of adverse events. Additionally, we performed a sub-analysis comparing the rate of adverse events in children discharged with normal vs. abnormal vital signs, as well as a standardized review of the nature of each adverse event.

RESULTS

Of 33,185 children discharged during the study period, 5,540 (17%) of these patients had at least one abnormal vital sign. There were 24/5,540 (0.43%) adverse events in the children with at least one abnormal vital sign vs. 47/27,645 (0.17%) adverse events in the children with normal vital signs [relative risk = 2.5 (95% confidence interval, 1.6 to 2.4)].However, upon review of each adverse event we found only one case that was related to the index visit, was potentially preventable by a 23-hour hospital observation, and caused permanent disability.

CONCLUSION

In our study population, 17% of the children were discharged with at least one abnormal vital sign, and there were very few adverse (0.43%) events associated with this practice. Heart rate was the most common abnormal vital sign leading to an adverse event. Severe adverse events that were potentially related to the abnormal vital sign(s) were exceedingly rare. Additional research is needed in broader populations to better determine the rate of adverse events and possible methods of avoiding them.

TRPV1 deletion exacerbates hyperthermic seizures in an age-dependent manner in mice

Febrile seizures (FS) are the most common seizure disorder to affect children. Although there is mounting evidence to support that FS occur when children have fever-induced hyperventilation leading to respiratory alkalosis, the underlying mechanisms of hyperthermia-induced hyperventilation and links to FS remain poorly understood. As transient receptor potential vanilloid-1 (TRPV1) receptors are heat-sensitive, play an important role in adult thermoregulation and modulate respiratory chemoreceptors, we hypothesize that TRPV1 activation is important for hyperthermia-induced hyperventilation leading to respiratory alkalosis and decreased FS thresholds, and consequently, TRPV1 KO mice will be relatively protected from hyperthermic seizures. To test our hypothesis we subjected postnatal (P) day 8-20 TRPV1 KO and C57BL/6 control mice to heated dry air. Seizure threshold temperature, latency and the rate of rise of body temperature during hyperthermia were assessed. At ages where differences in seizure thresholds were identified, head-out plethysmography was used to assess breathing and the rate of expired CO₂ in response to hyperthermia, to determine if the changes in seizure thresholds were related to respiratory alkalosis. Paradoxically, we observed a pro-convulsant effect of TRPV1 deletion (∼4min decrease in seizure latency), and increased ventilation in response to hyperthermia in TRPV1 KO compared to control mice at P20. This pro-convulsant effect of TRPV1 absence was not associated with an increased rate of expired CO₂, however, these mice had a more rapid rise in body temperature following exposure to hyperthermia than controls, and the expected linear relationship between body weight and seizure latency was absent. Based on these findings, we conclude that deletion of the TRPV1 receptor prevents reduction in hyperthermic seizure susceptibility in older mouse pups, via a mechanism that is independent of hyperthermia-induced respiratory alkalosis, but possibly involves impaired development of thermoregulatory mechanisms, although at present the mechanism remain unknown.

[What causes febrile convulsions?]

Febrile convulsions affect 2-5% of children in the age group from 6 months to 5 years. The convulsions seldom have negative consequences for the child's development, but may in rare cases constitute a debut symptom of epilepsy.

Acute respiratory infection and bacteraemia as causes of non-malarial febrile illness in African children: a narrative review

The replacement of "presumptive treatment for malaria" by "test before treat" strategies for the management of febrile illness is raising awareness of the importance of knowing more about the causes of illness in children who are suspected to have malaria but return a negative parasitological test. The most common cause of non-malarial febrile illness (NMFI) in African children is respiratory tract infection. Whilst the bacterial causes of NMFI are well known, the increasing use of sensitive techniques such as polymerase chain reaction (PCR) tests is revealing large numbers of viruses that are potential respiratory pathogens. However, many of these organisms are commonly present in the respiratory tract of healthy children so causality and risk factors for pneumonia remain poorly understood. Infection with a combination of viral and bacterial pathogens is increasingly recognised as important in the pathogenesis of pneumonia. Similarly, blood stream infections with organisms typically grown by aerobic culture are well known but a growing number of organisms that can be identified only by PCR, viral culture, or serology are now recognised to be common pathogens in African children. The high mortality of hospitalised children on the first or second day of admission suggests that, unless results are rapidly available, diagnostic tests to identify specific causes of illness will still be of limited use in guiding the potentially life saving decisions relating to initial treatment of children admitted to district hospitals in Africa with severe febrile illness and a negative test for malaria. Malaria control and the introduction of vaccines against Haemophilus influenzae type b and pneumococcal disease are contributing to improved child survival in Africa. However, increased parasitological testing for malaria is associated with increased use of antibiotics to which resistance is already high.

Association between hypocapnia and febrile seizures

The purpose of this study is to determine whether hyperthermia-induced hyperventilation with subsequent hypocapnia is relevant to febrile seizures in children. This is only the second study to measure pCO2 and pH values in children with febrile seizures. This prospective case-control study enrolled 18 children who presented with febrile seizures and 18 children who presented with a febrile illness without seizures. Venous blood gas analyses were measured both from the febrile seizure and control group. There was no significant difference in mean blood pH between the febrile seizure and control groups but blood pCO2 was significantly lower in the febrile seizure group. Patients with complex febrile seizures exhibited significantly lower pCO2 levels within 1 hour of seizure onset than patients with simplex febrile seizures. These data indicate that febrile seizures may be associated with hyperventilation and that the ensuing hypocapnia may contribute to the development of febrile seizures.

Metabolism, temperature, and ventilation

In mammals and birds, all oxygen used (VO2) must pass through the lungs; hence, some degree of coupling between VO2 and pulmonary ventilation (VE) is highly predictable. Nevertheless, VE is also involved with CO2 elimination, a task that is often in conflict with the convection of O2. In hot or cold conditions, the relationship between VE and VO2 includes the participation of the respiratory apparatus to the control of body temperature and water balance. Some compromise among these tasks is achieved through changes in breathing pattern, uncoupling changes in alveolar ventilation from VE. This article examines primarily the relationship between VE and VO2 under thermal stimuli. In the process, it considers how the relationship is influenced by hypoxia, hypercapnia or changes in metabolic level. The shuffling of tasks in emergency situations illustrates that the constraints on VE-VO2 for the protection of blood gases have ample room for flexibility. However, when other priorities do not interfere with the primary goal of gas exchange, VE follows metabolic rate quite closely. The fact that arterial CO2 remains stable when metabolism is changed by the most diverse circumstances (moderate exercise, cold, cold and exercise combined, variations in body size, caloric intake, age, time of the day, hormones, drugs, etc.) makes it unlikely that VE and metabolism are controlled in parallel by the condition responsible for the metabolic change. Rather, some observations support the view that the gaseous component of metabolic rate, probably CO2, may provide the link between the metabolic level and VE.

Derivation and validation of age and temperature specific reference values and centile charts to predict lower respiratory tract infection in children with fever: prospective observational study

OBJECTIVES

To develop reference values and centile charts for respiratory rate based on age and body temperature, and to determine how well these reference values can predict the presence of lower respiratory tract infections (LRTI) in children with fever.

DESIGN

Prospective observational study.

PARTICIPANTS

Febrile children aged at least 1 month to just under 16 years (derivation population, n = 1555; validation population, n = 671) selected from patients attending paediatric emergency departments or assessment units in hospitals.

SETTING

One hospital in the Netherlands in 2006 and 2008 (derivation population); one hospital in the Netherlands in 2003-05 and one hospital in the United Kingdom in 2005-06 (validation population).

INTERVENTION

We used the derivation population to produce respiratory rate centile charts, and calculated 50th, 75th, 90th, and 97th centiles of respiratory rate at a specific body temperature. Multivariable regression analysis explored associations between respiratory rate, age, and temperature; results were validated in the validation population by calculating diagnostic performance measures, z scores, and corresponding centiles of children with diagnoses of pneumonic LRTI (as confirmed by chest radiograph), non-pneumonic LRTI, and non-LRTI.

MAIN OUTCOME MEASURE

Age, respiratory rate (breaths/min) and body temperature (°C), presence of LRTI.

RESULTS

Respiratory rate increased overall by 2.2 breaths/min per 1°C rise (standard error 0.2) after accounting for age and temperature in the model. We observed no interactions between age, temperature, and respiratory rates. Age and temperature dependent cut-off values at the 97th centile were more useful for ruling in LRTI (specificity 0.94 (95% confidence interval 0.92 to 0.96), positive likelihood ratio 3.66 (2.34 to 5.73)) than existing respiratory rate thresholds such as Advanced Pediatrics Life Support values (0.53 (0.48 to 0.57), 1.59 (1.41 to 1.80)). However, centile cut-offs could not discriminate between pneumonic LRTI and non-pneumonic LRTI.

CONCLUSIONS

Age specific and temperature dependent centile charts describe new reference values for respiratory rate in children with fever. Cut-off values at the 97th centile were more useful in detecting the presence of LRTI than existing respiratory rate thresholds.

Neurobiological and physiological mechanisms of fever-related epileptiform syndromes

Febrile seizures (FS) are the most common type of convulsive events in children. FS have been extensively studied using animal models, where rat and mice pups are placed in a hyperthermic environment. Such work has largely focused on the consequences rather than on the mechanisms of experimental febrile seizures (eFS). We have recently shown that eFS are preceded by a dramatic rise in the rate of respiration. The consequent respiratory alkalosis affecting the brain and increasing neuronal excitability is a direct cause of the eFS [1]. If a similar mechanism contributes to human FS and other fever-related epileptiform syndromes, a number of factors operating at the molecular, cellular and systems level that have not been previously thought to be involved in their etiology must be considered. These include physiological and pathophysiological factors affecting CO(2) chemosensitivity as well as cellular and systemic mechanisms of acid-base regulation. Furthermore, a critical role for brain pH in FS points to novel types of susceptibility genes, which include genes coding pH-sensitive target proteins (e.g. neuronal ion channels) and pH-regulatory proteins. We will discuss these novel ideas and putative therapies based on them.

Chest radiography in children aged 2-59 months diagnosed with non-severe pneumonia as defined by World Health Organization: descriptive multicentre study in Pakistan

OBJECTIVES

To evaluate the chest radiographs of children diagnosed with non-severe pneumonia on the basis of the current World Health Organization guidelines (fast breathing alone) for radiological evidence of pneumonia.

DESIGN

Descriptive analysis.

SETTING

Outpatient departments of six hospitals in four cities in Pakistan.

PARTICIPANTS

2000 children with non-severe pneumonia were enrolled; 1932 children were selected for chest radiography.

INTERVENTIONS

Two consultant radiologists used standardised WHO definitions to evaluate chest radiographs; no clinical information was made available to them. If they disagreed, the radiographs were read by a third radiologist; the final classification was based on agreement between two of the three radiologists.

MAIN OUTCOME MEASURES

Presence or absence of pneumonia on radiographs.

RESULTS

Chest radiographs were reported normal in 1519 children (82%). Radiological evidence of pneumonia was reported in only 263 (14%) children, most of whom had interstitial pneumonitis. Lobar consolidation was present in only 26 children. The duration of illness did not correlate significantly with the presence of radiological changes (relative risk 1.17, 95% confidence interval 0.91 to 1.49).

CONCLUSION

Most children diagnosed with non-severe pneumonia on the basis of the current WHO definition had normal chest radiographs.

Experimental febrile seizures are precipitated by a hyperthermia-induced respiratory alkalosis

Febrile seizures are frequent during early childhood, and prolonged (complex) febrile seizures are associated with an increased susceptibility to temporal lobe epilepsy. The pathophysiological consequences of febrile seizures have been extensively studied in rat pups exposed to hyperthermia. The mechanisms that trigger these seizures are unknown, however. A rise in brain pH is known to enhance neuronal excitability. Here we show that hyperthermia causes respiratory alkalosis in the immature brain, with a threshold of 0.2-0.3 pH units for seizure induction. Suppressing alkalosis with 5% ambient CO2 abolished seizures within 20 s. CO2 also prevented two long-term effects of hyperthermic seizures in the hippocampus: the upregulation of the I(h) current and the upregulation of CB1 receptor expression. The effects of hyperthermia were closely mimicked by intraperitoneal injection of bicarbonate. Our work indicates a mechanism for triggering hyperthermic seizures and suggests new strategies in the research and therapy of fever-related epileptic syndromes.

Age related reference ranges of respiratory rate and heart rate for children in South Africa

BACKGROUND

The authors have recently presented reference ranges for heart rate and respiratory rate in healthy resting schoolchildren, aged 4-16 years, in the United Kingdom. There are no similar ranges for children in the developing world.

AIMS

To undertake a study in Cape Town, South Africa, to establish whether the UK ranges may be applied to socioeconomically disadvantaged groups.

METHODS

Data on 346 children in a township school were recorded; their height, weight, heart rate, and respiratory rate were compared to the UK ranges.

RESULTS

The two groups plotted closely together by height and weight on the UK 90 growth reference charts. There was no difference in heart rate between the two groups, and a difference of 0.46 breathes per minutes in respiratory rate, which is not felt to be of clinical significance.

CONCLUSION

The reference rages of heart and respiratory rate derived in the UK may be applied to children in developing world situations.

Influence of temperature on metabolism and breathing during mammalian ontogenesis

A literature survey of the ventilatory responses to changes in ambient temperature (T) in neonatal mammals reveals that, as in adults, the metabolic response to T is the major determining factor. In fact, the newborn's metabolic response to changes in T determines not only the pulmonary ventilation and the breathing pattern, but also the magnitude of the ventilatory responses to chemical stimuli and the intensity of the pulmonary reflexes at different T. The important difference from the adult is that in many neonatal mammals the control of body temperature (T(b)) is poorly developed. Hence, the metabolic response can be more similar to that of an ectothermic, rather than endothermic, animal, and T(b) can vary substantially with T. When hypoxia occurs in cold, T(b) can decrease greatly, because of the hypoxic drop in the thermoregulatory set-point, and this lowers pulmonary ventilation. Hence, in addition to the metabolic response, also the changes in T(b) are a factor modulating the ventilatory responses to T. Artificial warming of the newborn during hypoxia causes heat-dissipation responses that can be counterproductive. During ontogenesis, with prolonged cold conditions, the sustained alterations in metabolic rate and body growth do not modify the postnatal development of the respiratory control mechanisms. Presumably, this indicates that respiratory regulation develops independently from the individual's metabolic history.

Triage in the developing world--can it be done?

AIM

To assess guidelines for the emergency triage, assessment, and treatment (ETAT) of sick children presenting to hospitals in the developing world. This study pretested the guidelines in Malawi, assessing their performance when used by nurses compared to doctors trained in advanced paediatric life support (APLS).

METHODS

Triage was performed simultaneously by a nurse and assessing doctor on 2281 children presenting to the under 5s clinic. Each patient was allocated one of three priorities, according to the ETAT guidelines. Any variation between nurse and assessor was recorded on the assessment forms.

RESULTS

Nurses identified 92 children requiring emergency treatment and 661 with signs indicating a need for urgent medical assessment. One hundred and forty two (6.2%) had different priorities allocated by the APLS trained doctor, but these children did not tend to need subsequent admission. Eighty five per cent of admissions were prioritised to an emergency or urgent category.

CONCLUSION

Although there are no gold standards for comparison the ETAT guidelines appear to reliably select out the majority of patients requiring admission.

Ventilatory responses to changes in temperature in mammals and other vertebrates

This article reviews the relationship between pulmonary ventilation (VE) and metabolic rate (oxygen consumption) during changes in ambient temperature. The main focus is on mammals, although for comparative purposes the VE responses of ectothermic vertebrates are also discussed. First, the effects of temperature on pulmonary mechanics, chemoreceptors, and airway receptors are summarized. Then we review the main VE responses to cold and warm stimuli and their interaction with exercise, hypoxia, or hypercapnia. In these cases, mammals attempt to maintain both oxygenation and body temperature, although conflicts can arise because of the respiratory heat loss associated with the increase in ventilation. Finally, we consider the VE responses of mammals when body temperature changes, as during torpor, fever, sleep, and hypothermia. In ectotherms, during changes in temperature, VE control becomes part of a general strategy to maintain constant relative alkalinity and ensure a constancy of pH-dependent protein functions (alphastat regulation). In mammals on the other hand, VE control is aimed to balance metabolic needs with homeothermy. Therefore, alphastat regulation in mammals seems to have a low priority, and it may be adopted only in exceptional cases.

Association of fever and severe clinical course in bronchiolitis

Little attention has been given to the relation between fever and the severity of bronchiolitis. Therefore, the relation between fever and the clinical course of 90 infants (59 boys, 31 girls) hospitalised during one season with bronchiolitis was studied prospectively. Fever (defined as a single recording > 38.0 degrees C or two successive recording > 37.8 degrees C) was present in 28 infants. These infants were older (mean age, 5.3 v 4.0 months), had a longer mean hospital stay (4.2 v 2.7 days), and a more severe clinical course (71.0% v 29.0%) than those infants without fever. Radiological abnormalities (collapse/consolidation) were found in 60. 7% of the febrile group compared with 14.8% of the afebrile infants. These results suggest that monitoring of body temperature is important in bronchiolitis and that fever is likely to be associated with a more severe clinical course and radiological abnormalities.

Antimicrobial resistance and clinical effectiveness of co-trimoxazole versus amoxycillin for pneumonia among children in Pakistan: randomised controlled trial. Pakistan Co-trimoxazole Study Group

BACKGROUND

Co-trimoxazole is widely used in treatment of paediatric pneumonia in developing countries, but drug resistance may decrease its effectiveness. We studied the effectiveness of co-trimoxazole compared with that of amoxycillin in pneumonia therapy, and assessed the clinical impact of co-trimoxazole resistance.

METHODS

We recruited 595 children, aged 2-59 months, with non-severe or severe pneumonia (WHO criteria) diagnosed in the outpatient wards of two urban Pakistan hospitals. Patients were randomly assigned on a 2:1 basis co-trimoxazole (n=398) or amoxycillin (n=197) in standard WHO doses and dosing schedules, and were monitored in study wards. The primary outcome was inpatient therapy failure (clinical criteria) or clinical evidence of pneumonia at outpatient follow-up examination.

FINDINGS

There were 92 (23%) therapy failures in the co-trimoxazole group and 30 (15%) in the amoxycillin group (p=0.03)-26 (13%) versus 12 (12%) among children with non-severe pneumonia (p=0.856) and 66 (33%) versus 18 (18%) among those with severe pneumonia (p=0.009). For patients with severe pneumonia, age under 1 year (p=0.056) and positive chest radiographs (p=0.005) also predicted therapy failure. There was no significant association between antimicrobial minimum inhibitory concentration and outcome among bacteraemic children treated with co-trimoxazole.

INTERPRETATION

Co-trimoxazole provided effective therapy in non-severe pneumonia. For severe, life-threatening pneumonia, however, co-trimoxazole is less likely than amoxycillin to be effective.

Clinical overlap between malaria and severe pneumonia in Africa children in hospital

Data collected from 200 children admitted to a hospital on the Kenyan coast who met a broad definition of severe acute respiratory infection (ARI) indicated that simple clinical signs alone are unable absolutely to distinguish severe ARI and severe malaria. However, laboratory data showed that marked differences exist in the pathophysiology of unequivocal malaria and unequivocal ARI. Children in the former group had a higher mean oxygen saturation (97 vs. 94, P < 0.001), mean blood urea level (5.3 vs. 1.9 mmol/L, P < 0.001) and geometric mean lactate level (4.5 vs. 2.1 mmol/L, P < 0.001), and lower mean haemoglobin level (5.3 vs. 9.0 g/dL, P < 0.001) and base excess (-9.4 vs. -2.6, P < 0.001) than those in the latter group. Using these discriminatory variables it was estimated that up to 45% of children admitted with respiratory signs indicative of severe ARI probably had malaria as the primary diagnosis. Radiological examination supported this conclusion, indicating that pneumonia characterized by consolidation was uncommon in children with respiratory signs and a high malarial parasitaemia (> or = 10,000/microliters). There is no specific radiological sign of severe malaria. In practice, all children with respiratory signs warranting hospital admission in a malaria endemic area should be treated for both malaria and ARI unless blood film examination excludes malaria. In those with malaria and clinical evidence of acidosis, but no crackles, antibodies may be withheld while appropriate treatment for dehydration and anaemia is given. However, if clinical improvement is not rapid, antibiotics should be started.

Overlap in the clinical features of pneumonia and malaria in African children

Pneumonia and malaria are common causes of childhood morbidity and mortality in many developing countries and simple guidelines have been proposed to facilitate their diagnosis by relatively unskilled health workers. We have studied children in The Gambia attending out-patient and under-five clinics with clinically suspected pneumonia (cough or difficulty in breathing and a raised respiratory rate) during periods of high or low malaria transmission. During a period of high malaria transmission, 33% of these children had radiological evidence of pneumonia (with or without malaria parasitaemia) compared to 38% who had malaria parasitaemia, no radiological evidence of pneumonia and no other obvious cause of fever. Corresponding figures during a period of low malaria transmission were 48% and 6% respectively. The clinical overlap between pneumonia and malaria has important implications for case management strategies and evaluation of disease-specific interventions in regions in which both pneumonia and malaria are prevalent.