SMOKING CONNECTED TO POSTOPERATIVE COMPLICATIONS

Getting smokers to abstain from the habit for at least two months before knee or hip replacement surgery could help reduce their chances of postoperative complications. A recent study indicates that smoking cessation is helpful in reducing tobacco’s immunosuppressive effects and that this can speed a patient’s postoperative recovery.

Moller et al randomly assigned 120 patients to either a smoking intervention group or a control group six to eight weeks before they were scheduled for knee or hip replacement surgery. Those in the intervention group received counseling and nicotine replacement therapy, which was intended to lead to either complete smoking cessation or a 50% reduction in tobacco use.

Because some surgeries were cancelled during the study, 52 patients in the intervention group and 56 controls were available for final assessment. The intervention helped 36 patients to stop smoking and 14 to reduce their tobacco intake. Four of the controls stopped smoking on their own during the study.

Overall complication rates were 18% in the intervention group and 52% in controls. Wound-related complications developed in 5% and 31%, respectively; cardiovascular complications, in 0% and 10%; and need for secondary surgery, in 4% and 15%. The intervention group’s average length of stay was 11 days, compared with 13 days for the controls.

Given the effectiveness of the smoking intervention in reducing postoperative complication rates, the investigators concluded that such programs should be instituted six to eight weeks before surgery to encourage smoking cessation.

Moller A, Villebro N, Pedersen T, Tonnesen H. Effect of preoperative smoking intervention on postoperative complications: a randomised clinical trial. Lancet. 2002;359:114-117.

CAREFUL ANTIBIOTIC USE DECREASES ß-LACTAM RESISTANCE

Reducing the use of ß-lactam antibiotics in children could minimize their carriage rates of antibiotic-resistant pneumococci. Such a development would help not only the children so treated, but all those who come into contact with them as well.

Nasrin et al evaluated 461 children younger than 4 years during a 25-month period. Every six months, nasal swabs were used to obtain pneumococcal isolates, which were tested for antibiotic resistance. Histories of medical visits and drug treatment were kept by parents in diary records, describing the six months before each swab was taken; 456 of the records were at least 75% complete.

Of the isolates taken from children whose parents kept complete records, 14.9% were resistant to penicillin. The researchers found that children carrying antibiotic-resistant pneumococci were more likely than the other children to have been given a ß-lactam antibiotic in the two months before the resistant isolate was found; in fact, use of a ß-lactam more than doubled the risk that a resistant isolate would be detected. If a child had received both a penicillin and a cephalosporin, the odds ratio of carrying a resistant organism was 4.67.

However, the increase in risk appeared to correlate with the duration of antibiotic use. Use of a ß-lactam for less than eight days conferred no increase in risk, wheas the odd ration associated with more than 14 days’ administration was 2.5.

The researchers concluded that a reduction in the use of ß-lactam antibiotics in children should lower the rate of antibiotic resistance.

Nasrin D, Collingnon P, Roberts L, et al. Effect of ß-lactam antibiotic use in children on pneumococcal resistance to penicillin: prospective cohort study. BMJ. 2002;324:28-30.

COLD WEATHER: MORE DANGEROUS THAN INFECTION?

Increasing death rates during winter are more closely related to cold stress than to influenza infection. Recent research indicates that of 1,265 excess winter deaths that occurred in southeast England between 1970 and 1999, only 2.4% were flu-related.

Donaldson and Keatinge, the study’s authors, had noted that cold weather contributes to mortality increases due to a variety of causes, primarily respiratory diseases and thrombotic disorders. To better understand this pattern, they observed the maximum and minimum temperatures recorded at Heathrow airport during the aforementioned years to obtain averages. They compared this information with total yearly mortality related to cold temperatures, which was defined as the sum of daily deaths that occurred at temperatures colder than the one at which mortality was least often noted.

The researchers found that the annual rate of deaths due to influenza had declined during the study period, although there had been spikes in years when the population was affected by flu epidemics. They stated that 1976 held the worst of such outbreaks and that influenza-related deaths that year numbered 729 per million. In contrast, the total number of excess winter deaths that year was 2,308 per million.

Because preexisting evidence indicates that outdoor cold exposure is independently associated with excess winter mortality, Donaldson and Keatinge concluded that efforts to reduce outdoor cold stress could help reduce the number of excess deaths in winter.

Donaldson GC, Keatinge WR. Excess winter mortality: influenza or cold stress? Observational study. BMJ. 2002;324:89-90.

ALTERED HEMODYNAMICS IN WOMEN WITH OSA AND PREECLAMPSIA

If obstructive sleep apnea (OSA) coexists with preeclampsia in pregnancy, are the hemodynamic effects associated with OSA more pronounced? According to a recent study from Edwards et al, blood pressure responses may indeed be augmented in preeclamptic women.

Ten women with preeclampsia and a history of OSA were compared with 10 pregnant, normotensive women with a history of OSA who served as controls. All participants underwent overnight sleep polysomnography, which included blood pressure and heart rate measurements, as well as assessments of arterial oxyhemoglobin saturation, nasal flow, and respiratory effort.

Both groups of women had similar sleep architecture (for example, total sleep time, time spent in non-REM sleep, time spent in REM sleep, and number of arousals). The severity of their upper airway obstruction during sleep and their heart rate responses to apneic episodes were also similar.

However, the blood pressure responses were greater in the women with preeclampsia than in those without the disorder. During REM sleep (when the airway obstruction was more severe), systolic blood pressure rose by 46 mm Hg and diastolic pressure rose by 28 mm Hg in the women with preeclampsia, compared with systolic and diastolic pressure elevations of 24 mm Hg and 13 mm Hg, respectively, in the normotensive women. Similar, though less marked, blood pressure changes occurred in the two groups during non-REM sleep.

Edwards N, Blyton DM, Kirjavainen TT, Sullivan CE. Hemodynamic responses to obstructive respiratory events during sleep are augmented in women with preeclampsia. Am J Hypertens. 2001;14:1090-1095.

CLINICAL FEATURES CAN HELP AVOID CT FOR SUSPECTED MENINGITIS

Clinical features may be used to avoid the need for computed tomography (CT) in some adults with suspected meningitis. Recent research suggests that certain clinical clues can predict which of these patients are unlikely to have abnormal CT findings and therefore can safely undergo lumbar puncture.

Hasbun et al evaluated 235 patients with suspected meningitis who underwent CT of the head before lumbar puncture. Of these, 56 (24%) had abnormal CT results. Mass effects were evident in 11 (5%) patients.

Baseline clinical features that were associated with abnormal CT results included immunocompromise, older age (at least 60 years), history of central nervous system disease, history of seizure within the week before presentation, and evidence of neurologic dysfunction (eg, abnormal level of consciousness or visual fields, gaze palsy, inability to correctly answer two consecutive questions or follow two consecutive commands, arm or leg drift, and language abnormality).

In 96 patients, none of these clinical features were present at baseline. CT results were normal in 93 of the 96 patients, giving a negative predictive value of 97% to the absence of these features. Of the three patients with abnormal CT results, only one had evidence of a mild mass effect. All three underwent lumbar puncture safely; no evidence of brain herniation was detected during follow-up.

This finding led the researchers to conclude that adult patients with suspected meningitis who do not have these clinical features can safely receive lumbar puncture without first undergoing diagnostic head CT. They stated that this approach would have reduced the need for CT by 41% in their study.

Hasbun R, Abrahams J, Jekel J, Quagliarello VJ. Computed tomography of the head before lumbar puncture in adults with suspected meningitis. N Engl J Med. 2001;345:1727-1733.

DOES ERT AFFECT AIRWAY FUNCTION IN OLDER PATIENTS WITH ASTHMA?

According to a recent clinical study, neither the discontinuation nor reinitiation of estrogen replacement therapy (ERT) has an impact on objective measurements of asthma severity.

The prospective crossover study included 20 women who had been postmenopausal for two years, had taken ERT for the previous six months, and had been diagnosed with asthma. ERT was continued for the first 28 days of the study, discontinued for 28 days, and then resumed for the final 14 days. Peak respiratory flow rates were measured each day (in the morning and evening) during the 70-day trial. Pulmonary function tests were taken at days 14, 28, 42, 56, and 70 to objectively measure the patients’ airway function.

The mean predicted forced expiratory volume in one second (FEV1, expressed as a percentage of forced vital capacity) for days 14 and 28 during ERT was compared with that for days 42 and 56 during ERT withdrawal. These values (77% and 76%, respectively) were not significantly different, nor were they significantly different from the mean predicted FEV1 at day 70 (76%). In addition, no significant changes in FEV1 levels were noted in any patient during the study period.

Hepburn MJ, Dooley DP, Morris MJ. The effects of estrogen replacement therapy on airway function in postmenopausal, asthmatic women. Arch Intern Med. 2001;161:2717-2720.

IMIPENEM DOES NOT INCREASE SEIZURE RISK IN CRITICALLY ILL PATIENTS

Reports that administration of imipenem, a broad-spectrum antibiotic, may increase the risk of seizures in critically ill patients may not have taken other contributing factors into account, new research suggests. Other factors—including seizure history, comorbid metabolic derangements, and severity of the illness necessitating the antibiotic’s use—may have played underappreciated roles in seizure occurrence.

Koppel et al evaluated the charts of all patients who received imipenem at one 450-bed hospital during a six-month period. They focused on the aforementioned factors, as well as demographic features and pattern of seizure incidence before, during, and after imipenem use. Renal function and dosage were also considered.

Of the 75 patients identified, 63 never had seizures, eight had seizures before or after imipenem administration, and four had seizures while being given the drug. The incidence of seizures during imipenem administration was 4.0 per 1,000 patient days; it was 3.9 per 1,000 patient days before and after the drug was given.

Not surprisingly, patients who had a history of seizures had a higher seizure rate during hospitalization. Other factors that increased the risk of seizures included metabolic derangements, anoxia, and phenytoin discontinuation. Neither renal failure nor acute stroke, both of which could lead to increased cerebral imipenem concentrations, were associated with an increased seizure risk.

The researchers concluded that imipenem is safe when administered carefully. They also suggested that three steps—providing the proper dose of imipenem based on a patient’s body mass, correcting the dose in the presence of renal failure, and taking care not to deliver more than 2 g/d—would eliminate any possible additional seizure risk related to its use.

Koppel B, Hauser WA, Politis C, et al. Seizures in the critically ill: the role of imipenem. Epilepsia. 2001;42:1590-1593.

SMOKING CESSATION IMPROVES DAYTIME BP, HEART RATE

Does smoking cessation improve cardiovascular health in women? Recent results point to positive reductions in daytime systolic blood pressure (BP) and heart rate, as well as sympathetic nervous system activity.

A group of 66 postmenopausal women who smoked more than 10 cigarettes a day were randomly assigned in a 3:1 ratio either to attempt smoking cessation for six weeks or to join the wait-list control group that would not begin smoking cessation actions until after the six-week trial period. Ambulatory monitoring of BP and heart rate, as well as urinary catecholamine concentration measurements, determined the effects of nicotine withdrawal and helped to measure compliance.

Although BP levels and heart rate during sleep were not significantly altered, awake systolic BP decreased by an average of 3.6 mm Hg in the 19 subjects who successfully quit smoking and increased by an average of 1.7 mm Hg in the 15-person control group. In addition, daytime heart rates decreased by an average of 7 beats/ min in the smoking cessation group and stayed the same in the control group.

Furthermore, smoking cessation was linked to decreases in norepinephrine and epinephrine concentrations. The researchers suggest that this is probably due to reduced sympathetic nervous activation.

Oncken CA, White WB, Cooney JL, et al. Impact of smoking cessation on ambulatory blood pressure and heart rate in postmenopausal women. Am J Hypertens. 2001;14:942-949