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Penicillin-resistant Streptococcus pneumoniae in acute otitis media: Risk factors, susceptibility patterns, and antimicrobial management
ABSTRACTS
lators. They were then instrumented with right and left heart catheters, a right ventricular pacing electrode, and an airway flow measuring device. The pigs' neurologic status was assessed using a standardizedscale. The animals were allowed to partially recover from anesthesia and to spontaneouslyventilate before ventricular fibrillation was electrically induced. Fourminutes later, chest compressions were begun with a mechanical device. At this time, animals were assigned to one of two treatment groups: the A group received positive-pressureventilation at a 1:5 ratio to compressions,and the B group received 100% oxygenwith no measurable increase in airway pressure.The B group was oxygenated by passive diffusion, the effects of the chest compressions,and the spontaneous gasping that takes place during cardiopulmonary resuscitation (CPB).Twelve minutes into the arrest, up to two 300-J defibrillation attempts were made, followed by up to three 30-secondcycles of compressions and an additional 300-J shock. The surviving animals then were ventilated and observed for 3 hours, deinstrumented, and observed for an additional 48 hours. The authors found that the two groups did not significantly differ in either resuscitation success (A group, 7 of 11 animals; B group, 8 of 11 animals) or 48-hour survival rate. Although blood gas parameters such as pH, arterial partial pressure of carbon dioxide, and arterial bicarbonate concentration differed significantly after 8 minutes of compressions,arterial partial pressure of oxygen did not. Blood gas parameters in the two groups were not different in animals that survived resuscitation. Peffusion measures such as mean aortic pressure, cardiac index, heart rate, and serum lactate level did not differ after successful resuscitation. The laboratory conditions in this study guaranteed a patent airway and delivery of 100% oxygen at a nonventilating pressure.The authors concluded that the combination of precordial compressionand spontaneousgasping may have generated sufficient minute volume during cardiac arrest to account for the lack of difference between the groups. [Editor's note: Although the authors believe that the data show the adequacyof gasping respirations in this setting, it remains to be seen whether the animals would have sur-
FEBRUARY 1996
vived with a 21% fraction of inspired oxygen. The authors also reported arterial blood gas data that probably better reflect aortic environment than tissue hypoxia; the latter may be better assessed with mixed venous sampies. Other authors have shown that intubation is not a prerequisite for successful resuscitation. A recent study in Annals of Emergency Medicine (Berg et al, The need for ventilatory support during bystander CPR. September 1995;26:342-350)uses a similar experimental design but with an initial downtime of 2 minutes, room air, manual CPR with and without ventilations for 10 minutes, and advanced cardiac life support resuscitation algorithms. The group without ventilatory support also had their endotracbeal tubes removed. Again, in this somewhat more realistic setting, no significant difference was seen between the two groups in neurologic outcome or overall survival, and only a transitory difference was observed in arterial blood gas values during resuscitation. However, all studies to date have been animal studies with small numbers of subjects.] William Lober, MD
Penicillin-resistant Streptococcus pneumoniae in acute otitis media: Risk factors, susceptibility patterns, and antimicrobial management Block SL, Harrison CJ, Hedrick JA, et al Pediatr Infect Dis J 14:751-759 September 1995 This study was designed to investigate the prevalence of penicillin-resistant Streptococcuspneumoniae (PBSP)in a threecounty area in Kentucky.The patients evaluated in this study were healthy, predominantly white children, aged 2 months to 15 years, from a private pediatric population, who visited one of two pediatric offices between January 1992 and January 1994 and consented to the study. Cultures were obtained from children using tympanocentesis(90%), spontaneously ruptured tympanic membranes
27:2 ANNALS OF EMERGENCY MEDICINE
(5%), or tympanostomy tubes that were already draining (less than 24 hours; 4%). There were approximately 10,000 visits during this 2-year period by children with the diagnosis of acute otitis media (AOM). Overall, 283 pathogens were recovered from 246 patients. PRSPaccounted for 48% of all pneumococcal isolates. This group was further divided into highly PRSPand relatively PRSP organisms. ~-Lactamase production was detected in all Moraxella catarrhalis and 38% of Haemophilus influenzae organisms. Otitis-prone condition and increasing number of antibiotic courses before the day of culture were independently predictive risk factors for PRSP. During a 24-month period, highly PRSPand relatively PRSP organisms accounted for 8% and 9%, respectively, of 283 ear pathogens and 15% and 16%, respectively, of 157 pneumococcal isolates from AOM. This 31% incidence of PRSPfalls between the 17% incidence reported almost a decade ago in the United States and the 42% incidence recently reported from Israel. Highly PRSPstrains were more commonly found in children younger than 25 months. The authors further report that highly PBSP organisms displayed intermediate and even high levels of resistance to ceftriaxone and cefotaxime and high minimal inhibitory concentrations to most conventional oral antimicrobials for AOM. The authors recommend against single-dose ceftriaxone because indiscriminate, widespread use of a single-dose regimen may hasten resistance. Clavulanate has demonstrated in vivo synergism with amoxicillin against PRSPin preliminary data from an animal model. The authors conclude by recommending that first-line therapy should be high-dose amoxicillin (60 to 80 mg/kg per day) for outpatient, nontoxic young children with moderate to severe AOM Cases of AOM refractory to this therapy may be treated with amoxicillin-clavulanate at the above-mentioned amoxicillin dose. If PRSPis identified, then clindamycin orally (30 mg/kg per day)for 10 to 21 days or ceftriaxone (50 mg/kg per day) for 3 to 5 days may be appropriate.
[Editor's note: It is unclear from this study what the overall prevalence of PRSPis because only approximately 2% of patients
27 7
ABSTRACTS
with AOM in their pediatric practice took part.] Douglas McOaniel, MD
Noninvasive ventilation for acute exacerbations of chronic obstructive pulmonary disease Brochard L, ManceboJ, WysockiM, et al N Engl J Med 333:817-822 September 1995 This prospective European study was designed to investigate noninvasive pressuresupport ventilation in hospitalized patients with acute exacerbation of chronic obstructive pulmonary disease (COPD), in comparison with standard therapy. It is the authors' contention that in patients with COPD, noninvasive ventilation by face mask may be used in an attempt to avoid endotracheal intubation and the complications associated with mechanical ventilation. Between September 1990 and November 1991, 85 patients were randomly and prospectively recruited from a larger group of 275 patients with COPD, all of whom were admitted to five intensive care units. The same specific inclusion and exclusion criteria were used by all five hospitals to enroll patients in the study. Patients were included if they had acute exacerbation with respiratory acidosis but did not require immediate intubation. Patients assigned to the standard treatment group received oxygen limited to a maximal flow rate of 5 L/minute by nasal cannula in order to achieve an arterial oxygenation saturation higher than 90%. Medications included subcutaneous heparin, antibiotic agents, and bronchodilators. Patients assigned to the noninvasive group received the same medications as the patients in the standard treatment group, with the addition of noninvasive ventilation to provide an arterial oxygenation saturation higher than 90%. All the participating hospitals used the same noninvasive ventilation delivery apparatus. The primary outcome variable was the need for endotracheal intubation and mechanical ventilation at any time during the study. Thirty-one (74%) of the 42
27 8
patients in the standard treatment group required endotracheal intubation, compared with only 11 (26%) of the 43 patients in the noninvasive group. The results were consistent among the five centers. There were significant improvements in encephalopathy score, respiratory rate, partial pressure of arterial oxygen, and pH during the first hour of treatment in the noninvasive ventilation group, whereas the opposite was found in the standard treatment group. The hospital stay was significantly longer in the group receiving standard treatment (35 days) than in the group receiving noninvasive ventilation (23 days). The authors conclude that the mortality rate was significantly reduced and hospital stay was significantly shortened with the use of noninvasive ventilation. They further conclude that, in light of the rapidly reversible nature of most episodes of acute decompensation and the presence of ventilatory failure rather than hypoxemic lung failure, the results of this and previous studies suggest that patients with acute exacerbations of COPD should benefit from this approach.
Douglas McDaniel, MD
Limiting cardiac evaluation in patients with suspected myocardial contusion fildes Jd, getlej TM, Manglano R, et al Am Surg 61:832-835 September 1995 The evaluation of patients with suspected myocardial contusion can include serial ECGs, determinations of creatine phosphokinase (CPK)and its MB isoenzyme, continuous cardiac monitoring, and radiologic imaging studies. The authors of this prospective study wanted to determine what subset of blunt trauma patients considered at risk for myocardial contusion could safely undergo a limited cardiac evaluation (specifically, admission ECG and 24 hours of cardiac monitoring). The patient population consisted of 100 people who had mechanisms of injury consistent with myocardial contusion: motor vehicle crashes at more than 30 mph, falls of more than
30 feet, pedestrians struck by motor vehicles traveling at more than 30 mph, and home or industrial accidents in which myocardial injury was considered likely. All patients had a baseline ECG on admission. They were then assigned to one of two groups on the basis of the following criteria: (1) age, (2) hemodynamic stability, (3) results of baseline ECG, (4) history of heart disease, and (5) need for surgery or neurologic observation. Those patients with a normal ECG, hemodynamic stability (systolic blood pressure greater than 100), no history of heart disease, and no need for surgery or neurologic observation and who were younger than 55 years old were assigned to group 1 (n=74). All other patients were assigned to group 2 (n=19). Group 1 patients, in addition to the admission ECG, simply received 24 hours of continuous cardiac monitoring. Group 2 patients had a full cardiac evaluation, including an admission ECG, at least 24 hours of cardiac monitoring, serial ECGs, cardiac enzyme determinations, and either a multigated angiography scan (MUGA) or two-dimensional echocardiography (ECHO). Cardiac evaluation was considered to be positive for myocardial contusion if one or more of the following were present: (1) STsegment elevations, T-wave inversions, or conduction disturbances on serial ECGs;(2) significant arrhythmias on continuous cardiac monitoring; (3) one or more CPK-MB fractions greater than 4%; (4) right ventricular ejection fraction less than 40%, left ventricular ejection fraction less than 50%, or a regional wall motion abnormality on ECHO or MUGA. None of the patients in group 1 patients had cardiac complications that required treatment. There were no crossovers to group 2. Follow-up was obtained in 24% of group 1, and in all cases the ECG remained normal. None of these patients had complaints referable to a cardiac injury. Group 2 patients were so categorized for the following reasons: 9 (47.4%) had abnormal baseline ECGs, including Mobitz type I AV block, ST-segment elevations, T-wave inversions, postinfarction patterns, or multiple premature ventricular contractions; 7 (36.8%) had a history of heart disease; 4 (21%) underwent laparotomy; 1 (.5%) was admitted for neu-
ANNALS OF EMERGENCY MEDICINE 27:2 FEBRUARY 1996
lators. They were then instrumented with right and left heart catheters, a right ventricular pacing electrode, and an airway flow measuring device. The pigs' neurologic status was assessed using a standardizedscale. The animals were allowed to partially recover from anesthesia and to spontaneouslyventilate before ventricular fibrillation was electrically induced. Fourminutes later, chest compressions were begun with a mechanical device. At this time, animals were assigned to one of two treatment groups: the A group received positive-pressureventilation at a 1:5 ratio to compressions,and the B group received 100% oxygenwith no measurable increase in airway pressure.The B group was oxygenated by passive diffusion, the effects of the chest compressions,and the spontaneous gasping that takes place during cardiopulmonary resuscitation (CPB).Twelve minutes into the arrest, up to two 300-J defibrillation attempts were made, followed by up to three 30-secondcycles of compressions and an additional 300-J shock. The surviving animals then were ventilated and observed for 3 hours, deinstrumented, and observed for an additional 48 hours. The authors found that the two groups did not significantly differ in either resuscitation success (A group, 7 of 11 animals; B group, 8 of 11 animals) or 48-hour survival rate. Although blood gas parameters such as pH, arterial partial pressure of carbon dioxide, and arterial bicarbonate concentration differed significantly after 8 minutes of compressions,arterial partial pressure of oxygen did not. Blood gas parameters in the two groups were not different in animals that survived resuscitation. Peffusion measures such as mean aortic pressure, cardiac index, heart rate, and serum lactate level did not differ after successful resuscitation. The laboratory conditions in this study guaranteed a patent airway and delivery of 100% oxygen at a nonventilating pressure.The authors concluded that the combination of precordial compressionand spontaneousgasping may have generated sufficient minute volume during cardiac arrest to account for the lack of difference between the groups. [Editor's note: Although the authors believe that the data show the adequacyof gasping respirations in this setting, it remains to be seen whether the animals would have sur-
FEBRUARY 1996
vived with a 21% fraction of inspired oxygen. The authors also reported arterial blood gas data that probably better reflect aortic environment than tissue hypoxia; the latter may be better assessed with mixed venous sampies. Other authors have shown that intubation is not a prerequisite for successful resuscitation. A recent study in Annals of Emergency Medicine (Berg et al, The need for ventilatory support during bystander CPR. September 1995;26:342-350)uses a similar experimental design but with an initial downtime of 2 minutes, room air, manual CPR with and without ventilations for 10 minutes, and advanced cardiac life support resuscitation algorithms. The group without ventilatory support also had their endotracbeal tubes removed. Again, in this somewhat more realistic setting, no significant difference was seen between the two groups in neurologic outcome or overall survival, and only a transitory difference was observed in arterial blood gas values during resuscitation. However, all studies to date have been animal studies with small numbers of subjects.] William Lober, MD
Penicillin-resistant Streptococcus pneumoniae in acute otitis media: Risk factors, susceptibility patterns, and antimicrobial management Block SL, Harrison CJ, Hedrick JA, et al Pediatr Infect Dis J 14:751-759 September 1995 This study was designed to investigate the prevalence of penicillin-resistant Streptococcuspneumoniae (PBSP)in a threecounty area in Kentucky.The patients evaluated in this study were healthy, predominantly white children, aged 2 months to 15 years, from a private pediatric population, who visited one of two pediatric offices between January 1992 and January 1994 and consented to the study. Cultures were obtained from children using tympanocentesis(90%), spontaneously ruptured tympanic membranes
27:2 ANNALS OF EMERGENCY MEDICINE
(5%), or tympanostomy tubes that were already draining (less than 24 hours; 4%). There were approximately 10,000 visits during this 2-year period by children with the diagnosis of acute otitis media (AOM). Overall, 283 pathogens were recovered from 246 patients. PRSPaccounted for 48% of all pneumococcal isolates. This group was further divided into highly PRSPand relatively PRSP organisms. ~-Lactamase production was detected in all Moraxella catarrhalis and 38% of Haemophilus influenzae organisms. Otitis-prone condition and increasing number of antibiotic courses before the day of culture were independently predictive risk factors for PRSP. During a 24-month period, highly PRSPand relatively PRSP organisms accounted for 8% and 9%, respectively, of 283 ear pathogens and 15% and 16%, respectively, of 157 pneumococcal isolates from AOM. This 31% incidence of PRSPfalls between the 17% incidence reported almost a decade ago in the United States and the 42% incidence recently reported from Israel. Highly PRSPstrains were more commonly found in children younger than 25 months. The authors further report that highly PBSP organisms displayed intermediate and even high levels of resistance to ceftriaxone and cefotaxime and high minimal inhibitory concentrations to most conventional oral antimicrobials for AOM. The authors recommend against single-dose ceftriaxone because indiscriminate, widespread use of a single-dose regimen may hasten resistance. Clavulanate has demonstrated in vivo synergism with amoxicillin against PRSPin preliminary data from an animal model. The authors conclude by recommending that first-line therapy should be high-dose amoxicillin (60 to 80 mg/kg per day) for outpatient, nontoxic young children with moderate to severe AOM Cases of AOM refractory to this therapy may be treated with amoxicillin-clavulanate at the above-mentioned amoxicillin dose. If PRSPis identified, then clindamycin orally (30 mg/kg per day)for 10 to 21 days or ceftriaxone (50 mg/kg per day) for 3 to 5 days may be appropriate.
[Editor's note: It is unclear from this study what the overall prevalence of PRSPis because only approximately 2% of patients
27 7
ABSTRACTS
with AOM in their pediatric practice took part.] Douglas McOaniel, MD
Noninvasive ventilation for acute exacerbations of chronic obstructive pulmonary disease Brochard L, ManceboJ, WysockiM, et al N Engl J Med 333:817-822 September 1995 This prospective European study was designed to investigate noninvasive pressuresupport ventilation in hospitalized patients with acute exacerbation of chronic obstructive pulmonary disease (COPD), in comparison with standard therapy. It is the authors' contention that in patients with COPD, noninvasive ventilation by face mask may be used in an attempt to avoid endotracheal intubation and the complications associated with mechanical ventilation. Between September 1990 and November 1991, 85 patients were randomly and prospectively recruited from a larger group of 275 patients with COPD, all of whom were admitted to five intensive care units. The same specific inclusion and exclusion criteria were used by all five hospitals to enroll patients in the study. Patients were included if they had acute exacerbation with respiratory acidosis but did not require immediate intubation. Patients assigned to the standard treatment group received oxygen limited to a maximal flow rate of 5 L/minute by nasal cannula in order to achieve an arterial oxygenation saturation higher than 90%. Medications included subcutaneous heparin, antibiotic agents, and bronchodilators. Patients assigned to the noninvasive group received the same medications as the patients in the standard treatment group, with the addition of noninvasive ventilation to provide an arterial oxygenation saturation higher than 90%. All the participating hospitals used the same noninvasive ventilation delivery apparatus. The primary outcome variable was the need for endotracheal intubation and mechanical ventilation at any time during the study. Thirty-one (74%) of the 42
27 8
patients in the standard treatment group required endotracheal intubation, compared with only 11 (26%) of the 43 patients in the noninvasive group. The results were consistent among the five centers. There were significant improvements in encephalopathy score, respiratory rate, partial pressure of arterial oxygen, and pH during the first hour of treatment in the noninvasive ventilation group, whereas the opposite was found in the standard treatment group. The hospital stay was significantly longer in the group receiving standard treatment (35 days) than in the group receiving noninvasive ventilation (23 days). The authors conclude that the mortality rate was significantly reduced and hospital stay was significantly shortened with the use of noninvasive ventilation. They further conclude that, in light of the rapidly reversible nature of most episodes of acute decompensation and the presence of ventilatory failure rather than hypoxemic lung failure, the results of this and previous studies suggest that patients with acute exacerbations of COPD should benefit from this approach.
Douglas McDaniel, MD
Limiting cardiac evaluation in patients with suspected myocardial contusion fildes Jd, getlej TM, Manglano R, et al Am Surg 61:832-835 September 1995 The evaluation of patients with suspected myocardial contusion can include serial ECGs, determinations of creatine phosphokinase (CPK)and its MB isoenzyme, continuous cardiac monitoring, and radiologic imaging studies. The authors of this prospective study wanted to determine what subset of blunt trauma patients considered at risk for myocardial contusion could safely undergo a limited cardiac evaluation (specifically, admission ECG and 24 hours of cardiac monitoring). The patient population consisted of 100 people who had mechanisms of injury consistent with myocardial contusion: motor vehicle crashes at more than 30 mph, falls of more than
30 feet, pedestrians struck by motor vehicles traveling at more than 30 mph, and home or industrial accidents in which myocardial injury was considered likely. All patients had a baseline ECG on admission. They were then assigned to one of two groups on the basis of the following criteria: (1) age, (2) hemodynamic stability, (3) results of baseline ECG, (4) history of heart disease, and (5) need for surgery or neurologic observation. Those patients with a normal ECG, hemodynamic stability (systolic blood pressure greater than 100), no history of heart disease, and no need for surgery or neurologic observation and who were younger than 55 years old were assigned to group 1 (n=74). All other patients were assigned to group 2 (n=19). Group 1 patients, in addition to the admission ECG, simply received 24 hours of continuous cardiac monitoring. Group 2 patients had a full cardiac evaluation, including an admission ECG, at least 24 hours of cardiac monitoring, serial ECGs, cardiac enzyme determinations, and either a multigated angiography scan (MUGA) or two-dimensional echocardiography (ECHO). Cardiac evaluation was considered to be positive for myocardial contusion if one or more of the following were present: (1) STsegment elevations, T-wave inversions, or conduction disturbances on serial ECGs;(2) significant arrhythmias on continuous cardiac monitoring; (3) one or more CPK-MB fractions greater than 4%; (4) right ventricular ejection fraction less than 40%, left ventricular ejection fraction less than 50%, or a regional wall motion abnormality on ECHO or MUGA. None of the patients in group 1 patients had cardiac complications that required treatment. There were no crossovers to group 2. Follow-up was obtained in 24% of group 1, and in all cases the ECG remained normal. None of these patients had complaints referable to a cardiac injury. Group 2 patients were so categorized for the following reasons: 9 (47.4%) had abnormal baseline ECGs, including Mobitz type I AV block, ST-segment elevations, T-wave inversions, postinfarction patterns, or multiple premature ventricular contractions; 7 (36.8%) had a history of heart disease; 4 (21%) underwent laparotomy; 1 (.5%) was admitted for neu-
ANNALS OF EMERGENCY MEDICINE 27:2 FEBRUARY 1996