The morbidity of Guillain-Barré syndrome admitted to the intensive care unit

Patients with severe forms of Guillain-Barré syndrome (GBS) require intensive care. Specific treatment, catheterization, and devices may increase morbidity in the intensive care unit (ICU). To understand the spectrum of morbidity associated with ICU care, the authors studied 114 patients with GBS. Major morbidity occurred in 60% of patients. Complications were uncommon if ICU stay was less than 3 weeks. Respiratory complications such as pneumonia and tracheobronchitis occurred in half of the patients and were linked to mechanical ventilation. Systemic infection occurred in one-fifth of patients and was more frequent with increasing duration of ICU admission. Direct complications of treatment and invasive procedures occurred infrequently. Life-threatening complications such as gastrointestinal bleeding and pulmonary embolism were very uncommon. Pulmonary morbidity predominates in patients with severe GBS admitted to the ICU. Attention to management of mechanical ventilation and weaning is important to minimize this complication of GBS. Other causes of morbidity in a tertiary center ICU are uncommon.

Zinc and vitamin A supplementation in Indigenous Australian children hospitalised with lower respiratory tract infection: a randomised controlled trial

Objective: To evaluate the efficacy of supplementation with zinc and vitamin A in Indigenous children hospitalised with acute lower respiratory infection (ALRI). Design: Randomised controlled, 2-by-2 factorial trial of supplementation with zinc and vitamin A. Setting and participants: 187 Indigenous children aged < 11 years hospitalised with 215 ALRI episodes at Alice Springs Hospital (April 2001 to July 2002). Interventions: Vitamin A was administered on Days 1 and 5 of admission at a dose of 50 000 IU (infants under 12 months), or 100 000 IU; and zinc sulfate was administered daily for 5 days at a daily dose of 20 mg (infants under 12 months) or 40 mg. Main outcome measure: Time to clinical recovery from fever and tachypnoea, duration of hospitalisation, and readmission for ALRI within 120 days. Results: There was no clinical benefit of supplementation with vitamin A, zinc or the two combined, with no significant difference between zinc and no-zinc, vitamin A and no-vitamin A or zinc + vitamin A and placebo groups in time to resolution of fever or tachypnoea, or duration of hospitalisation. Instead, we found increased morbidity; children given zinc had increased risk of readmission for ALRI within 120 days (relative risk, 2.4; 95% CI, 1.003–6.1). Conclusion: This study does not support the use of vitamin A or zinc supplementation in the management of ALRI requiring hospitalisation in Indigenous children living in remote areas. Even in populations with high rates of ALRI and poor living conditions, vitamin A and zinc therapy may not be useful. The effect of supplementation may depend on the prevalence of deficiency of these micronutrients in the population.

Respiratory and cardiovascular responses to hypoxia in the Australian lungfish

Simultaneous measurements of pulmonary blood flow (qPA), coeliacomesenteric blood flow (qCoA), dorsal aortic blood pressure (PDA), heart rate (fH) and branchial ventilation frequency (fv) were made in the Australian lungfish, /Neoceratodus forsteri, /during air breathing and aquatic hypoxia. The cho­linergic and adrenergic influences on the cardiovascular system were investigated during normoxia using pharmacological agents, and the presence of catecholamines and serotonin in different tissues was investi­gated using histochemistry. Air breathing rarely occurred during normoxia but when it did, it was always associated with increased pulmonary blood flow. The pulmonary vasculature is influenced by both a cho­linergic and adrenergic tonus whereas the coeliacomesenteric vasculature is influenced by a β-adrenergic vasodilator mechanism. No adrenergic nerve fibers could be demonstrated in /Neoceratodus /but catecholamine-containing endothelial cells were found in the atrium of the heart. In addition, serotonin-­immunoreactive cells were demonstrated in the pulmonary epithelium. The most prominent response to aquatic hypoxia was an increase in gill breathing frequency followed by an increased number of air breaths together with increased pulmonary blood flow. It is clear from the present investigation that /Neoceratodus /is able to match cardiovascular performance to meet the changes in respiration during hypoxia.

Changes in neutrophil surface receptor expression, degranulation, and respiratory burst activity following moderate and high intensity exercise

Intense exercise stimulates the systemic release of a variety of factors that alter neutrophil surface receptor expression and functional activity. These alterations may influence resistance to infection after intense exercise. The aim of this study was to examine the influence of exercise intensity on neutrophil receptor expression, degranulation (measured by plasma and intracellular myeloperoxidase concentrations), and respiratory burst activity. Ten well-trained male runners ran on a treadmill for 60 min at 60% [moderate-intensity exercise (MI)] and 85% maximal oxygen consumption [high-intensity exercise (HI)]. Blood was drawn immediately before and after exercise and at 1 h postexercise. Immediately after HI, the expression of the neutrophil receptor CD16 was significantly below preexercise values (P < 0.01), whereas MI significantly reduced CD35 expression below preexercise values (P < 0.05). One hour after exercise at both intensities, there was a significant decline in CD11b expression (P < 0.05) and a further decrease in CD16 expression compared with preexercise values (P < 0.01). CD16 expression was lower 1 h after HI than 1 h after MI (P < 0.01). Immediately after HI, intracellular myeloperoxidase concentration was less than preexercise values (P < 0.01), whereas plasma myeloperoxidase concentration was greater (P < 0.01), indicating that HI stimulated neutrophil degranulation. Plasma myeloperoxidase concentration was higher immediately after HI than after MI (P < 0.01). Neutrophil respiratory burst activity increased after HI (P < 0.01). In summary, both MI and HI reduced neutrophil surface receptor expression. Although CD16 expression was reduced to a greater extent after HI, this reduction did not impair neutrophil degranulation and respiratory burst activity.

Children’s respiratory health and daily particulate levels in ten non-urban communities

We conducted a study to assess the association between the acute respiratory health of children and the levels of particulates in communities near and away from active opencast coal mines. The study enrolled children aged 1–11 years from the general population of five socioeconomically matched pairs of nonurban communities in northern England. Diaries of respiratory events were collected for 1405 children, and information was collected on the consultations of 2442 children with family/general practitioners over the 6-week study periods during 1996–1997, with concurrent monitoring of particulate levels. The associations found between daily PM10 levels and respiratory symptoms were frequently small and positive and sometimes varied between communities. The magnitude of these associations were in line with those from previous studies, even though daily particulate levels were low, and the children were drawn from the general population, rather than from the population with respiratory problems. The associations among asthma reliever use, consultations with general practitioners, and daily particulate levels were of a similar strength but estimated less precisely. The strength of association between all respiratory health measures and particulate levels was similar in communities near and away from opencast coal mining sites.

Nest temperature and respiratory gases during natural incubation in the broad-shelled river turtle, Chelodina expansa (Testudinata : Chelidae)

Temperature was monitored in three natural nests, and oxygen and carbon dioxide partial pressure monitored in one natural nest of the broad-shelled river turtle, Chelodina expansa, throughout incubation. Nest temperature decreased after nest construction in autumn, remained low during winter and gradually increased in spring to a maximum in summer. In a nest where temperature was recorded every hour, temperature typically fluctuated through a 2 degrees C cycle on a daily basis throughout the entire incubation period, and the nest always heated faster than it cooled. Oxygen and carbon dioxide partial pressures in this nest were similar to soil oxygen and carbon dioxide partial pressures for the first 5 months of incubation, but nest respiratory gas tensions deviated from the surrounding soil over the last three months of incubation. Nest respiratory gas tensions were not greatly different from those in the atmosphere above the ground except after periods of rain. After heavy rain during the last 3 months of incubation the nest became moderately hypoxic (P-O2 similar to 100 Torr) and hypercapnic (P-CO2 similar to 50 Torr) for several successive days. These short periods of hypoxia and hypercapnia were not lethal.

The respiratory risks of cannabis smoking

Cannabis users have recently been told that cannabis smoking is ª relatively harmlessº 1 and presents ª minimal danger to the lungsº .2 These statements seem at odds with the similarities between the carcinogens and other toxic constituents in tobacco and cannabis smoke, the fact that un® ltered cannabis smoke contains more of some carcinogens than ® ltered tobacco smoke3,4 and other evidence that chronic cannabis smoking has adverse respiratory effects.5

Changes in intra-abdominal pressure during postural and respiratory activation of the human diaphragm

In humans, when the stability of the trunk is challenged in a controlled manner by repetitive movement of a limb, activity of the diaphragm becomes tonic but is also modulated at the frequency of limb movement. In addition, the tonic activity is modulated by respiration. This study investigated the mechanical output of these components of diaphragm activity. Recordings were made of costal diaphragm, abdominal, and erector spinae muscle electromyographic activity; intra-abdominal, intrathoracic, and transdiaphragmatic pressures; and motion of the rib cage, abdomen, and arm. During limb movement the diaphragm and transversus abdominis were tonically active with added phasic modulation at the frequencies of both respiration and limb movement. Activity of the other trunk muscles was not modulated by respiration. Intra-abdominal pressure was increased during the period of limb movement in proportion to the reactive forces from the movement. These results show that coactivation of the diaphragm and abdominal muscles causes a sustained increase in intra-abdominal pressure, whereas inspiration and expiration are controlled by opposing activity of the diaphragm and abdominal muscles to vary the shape of the pressurized abdominal cavity.

Co-morbidity between alcohol, tobacco and cannabis use: reply to David Fergusson

No abstract

Postural activity of the diaphragm is reduced in humans when respiratory demand increases

1. Respiratory activity of the diaphragm and other respiratory muscles is normally co-ordinated with their other functions, such as for postural control of the trunk when the limbs move. The integration may occur by summation of two inputs at the respiratory motoneurons. The present study investigated whether postural activity of the diaphragm changed when respiratory drive increased with hypercapnoea. 2. Electromyographic (EMG) recordings of the diaphragm and other trunk muscles were made with intramuscular electrodes in 13 healthy volunteers. Under control conditions and while breathing through increased dead-space,subjects made rapid repetitive arm movements to disturb the stability of the spine for four periods each lasting 10 s, separated by 50 s. 3. End-tidal CO2, and ventilation increased for the first 60-120 s of the trial then reached a plateau. During rapid arm movement at the start of dead-space breathing, diaphragm EMG became tonic with superimposed modulation at the frequencies of respiration and arm movement. However, when the arm was moved after 60 s of hypercapnoea, the tonic diaphragm EMG during expiration and the phasic activity with arm movement were reduced or absent. Similar changes occurred for the expiratory muscle transversus abdominis, but not for the erector spinae. The mean amplitude of intra-abdominal pressure and the phasic changes with arm movement were reduced after 60 s of hypercapnoea. 4. The present data suggest that increased central respiratory drive may attenuate the postural commands reaching motoneurons. This attenuation can affect the key inspiratory and expiratory muscles and is likely to be co-ordinated at a pre-motoneuronal site.

Epidural anaesthesia and analgesia and outcome of major surgery: a randomised trial

Background Epidural block is widely used to manage major abdominal surgery and postoperative analgesia, but its risks. and benefits are uncertain. We compared adverse outcomes in high-risk patients managed for major surgery with epidural block or alternative analgesic regimens with general anaesthesia in a multicentre randomised trial. Methods 915 patients undergoing major abdominal surgery with one of nine defined comorbid states to identify high-risk status were randomly assigned intraoperative epidural anaesthesia and postoperative epidural analgesia for 72 h with general anaesthesia (site of epidural selected to provide optimum block) or control. The primary endpoint was death at 30 days or major postsurgical morbidity. Analysis by intention to treat involved 447 patients assigned epidural and 441 control. Findings 255 patients (57.1%) in the epidural group and 268 (60.7%) in the control group had at least one morbidity endpoint or died (p=0.29). Mortality at 30 days was low in both groups (epidural 23 [5.1%], control 19 [4.3%], p=0.67). Only one of eight categories of morbid endpoints in individual systems (respiratory failure) occurred less frequently in patients managed with epidural techniques (23% vs 30%, p=0.02). Postoperative epidural analgesia was associated with lower pain scores during the first 3 postoperative days. There were no major adverse consequences of epidural-catheter insertion. Interpretation Most adverse morbid outcomes in high-risk patients undergoing major abdominal surgery are not reduced by use of combined epidural and general anaesthesia and postoperative epidural analgesia. However, the improvement in analgesia, reduction in respiratory failure, and the low risk of serious adverse consequences suggest that many high-risk patients undergoing major intra-abdominal surgery will receive substantial benefit from combined general and epidural anaesthesia intraoperatively with continuing postoperative epidural analgesia.

Perioperative epidural analgesia and outcome after major abdominal surgery in high-risk patients

In a primary analysis of a large recently completed randomized trial in 915 high-risk patients undergoing major abdominal surgery, we found no difference in outcome between patients receiving perioperative epidural analgesia and those receiving IV opioids, apart from the incidence of respiratory failure. Therefore, we performed a selected number of predetermined subgroup analyses to identify specific types of patients who may have derived benefit from epidural analgesia. We found no difference in outcome between epidural and control groups in subgroups at increased risk of respiratory or cardiac complications or undergoing aortic surgery, nor in a subgroup with failed epidural block (all P > 0.05). There was a small reduction in the duration of postoperative ventilation (geometric mean [SD]: control group, 0.3 [6.5] h, versus epidural group, 0.2 [4.8] h, P = 0.048). No differences were found in length of stay in intensive care or in the hospital. There was no relationship between frequency of use of epidural analgesia in routine practice outside the trial and benefit from epidural analgesia in the trial. We found no evidence that perioperative epidural analgesia significantly influences major morbidity or mortality after major abdominal surgery.

Patterns of co-morbidity between alcohol use and other substance use in the Australian population

The present study describes patterns of co-morbidity between alcohol use and other substance use problems in the Australian population using data from the 1997 National Survey of Mental Health and Well-Being. Multiple regression analyses examined whether the observed associations between alcohol and other drug use disorders were explained by other variables, including demographic characteristics and neuroticism. We also assessed whether the presence of co-morbid substance use disorders affected treatment seeking for a mental health problem. Alcohol use was related strongly to the use of other substances. Those who did not report alcohol use within the past 12 months were less likely to report using tobacco, cannabis, sedatives, stimulants or opiates. Higher rates again were observed among those with alcohol use disorders: half (51%) of those who were alcohol-dependent were regular tobacco smokers, one-third had used cannabis (32%); 15% reported other drug use; 15% met criteria for a cannabis use disorder and 7% met criteria for another drug use disorder. These associations were not accounted for by the demographic and other variables considered here. Co-morbid substance use disorders (sedatives, stimulants or opioids) predicted a high likelihood of seeking treatment for a mental health problem among alcohol-dependent people.