Initial Arterial Blood Gas Research Articles

Severe Acute Asthma in a Pediatric Intensive Care Unit: Six Years' Experience

The management of children with severe acute asthma who required admission to the intensive care (ICU) of this hospital during 1982 to 1988 was reviewed retrospectively. A total of 89 children were admitted to the ICU on 125 occasions. During the study period, 24% of the patients were admitted to the ICU on more than one occasion. Prior to admission to this hospital, patients had been symptomatic for a mean of 48 hours. Although all patients had received bronchodilators before admission to hospital, only 23% of patients had received oral corticosteroids. According to initial arterial blood gas values determined in the ICU, 77% of the patients had hypercapnia (PaCO2 greater than 45 mm Hg). The pharmacologic agents used in the ICU included nebulized beta 2-agonists (100% of admissions), theophylline (99%), steroids (94%), nebulized ipratropium bromide (10%), IV albuterol (38%), and IV isoproterenol (10%). Mechanical ventilation was necessary in 33% of admissions; the mean duration of ventilation was 32 hours. Ten patients had pneumothorax; in six cases, these were related to mechanical ventilation. Three of the patients who received mechanical ventilation died, representing a mortality of 7.5%. In each of these patients, sudden, severe asthma episodes had developed at home, resulting in respiratory arrest. They had evidence of hypoxic encephalopathy at the time of admission to the ICU and eventually were declared brain dead. It was concluded that delay in seeking medical care and underuse of oral corticosteroids at home may have contributed to the need for ICU admission.(ABSTRACT TRUNCATED AT 250 WORDS)

Field airway management of the trauma patient: The efficacy of bag mask ventilation

There is no consensus on what constitutes appropriate field airway management in the seriously injured semiconscious patient. The respiratory complications in a selected group of patients who were transported from the scene of an accident by a helicopter service whose policy was to perform endotracheal intubation on only deeply obtunded patients and manage others with bag mask ventilation are reported. Respiratory compromise was defined as follows: partial pressure of oxygen <65 torr on initial hospital arterial blood gases, partial pressure of carbon dioxide >45 torr on initial hospital arterial blood gases, or radiographic and clinical evidence of aspiration pneumonitis within 5 days of admission to the hospital. From a total of 116 patients transported from the scene of an accident during the period of this investigation, there were 42 patients with Trauma Scores between 4 and 14 whose records were studied in detail. Ten of these patients had adequate perfusion and abnormal arterial blood gases after arrival at the receiving hospital. Five patients might have benefited from endotracheal intubation in the field, but there were no preventable deaths. Neurologic status of the patient appeared to be more useful than respiratory status in predicting respiratory compromise.

Indications for intubation in blunt chest trauma.

The value of endotracheal intubation and internal stabilization in severe chest injuries is well known. Recent reports have proposed that many such patients can be managed without intubation. To determine which patients need intubation we reviewed 140 patients with three or more rib fractures who presented to our hospitals from 1 January 1979 through 31 December 1983: 119 nonintubated patients (Group A); 13 patients intubated on admission (Group B); five patients intubated after hospital day 1 (Group C); and three patients intubated questionably on admission (Group D). The purpose of this report was to identify the factors which indicated severe pulmonary injury necessitating intubation. The need for intubation was correlated with five risk factors: 1) initial respiratory rate of over 25 min; 2) pulse greater than 100 min; 3) systolic blood pressure less than 100 mm Hg; 4) poor initial arterial blood gas; 5) the presence of other injuries. There was no correlation between severity of pulmonary injury and number of fractures, bilateral and/or segmental fractures, flail chest, contusion of lung, or age of patient. There was a greater percentage of complications and deaths in intubated patients (Groups B, C, and D). Group C patients all had poor initial blood gases and were erroneously not intubated early, even though 60% of them had three or more risk factors, as did Group B patients. Only 4% of patients who did not need intubation (Group A) had three or more risk factors. Group D patients were intubated without apparent indication. They had good initial blood gas levels and only one risk factor.(ABSTRACT TRUNCATED AT 250 WORDS)

Magnesium and potassium therapy in multifocal atrial tachycardia

Eight patients with multifocal atrial tachycardia received 7 to 12 gm of magnesium sulfate intravenously over a 5-hour period. Potassium supplements were given initially or added later. Initial arterial blood gases showed mean pH 7.48 ± 0.03, PcO 2 39.7 torr, Po 2 72 torr, HCO 3 − 29.8 ± 4.5 mEq/L, and base excess 6.84 ± 3.78 mEq/L. Initial serum magnesium correlated well with initial serum potassium. Three patients had subnormal levels of magnesium and potassium. The level of serum magnesium rose with an intravenous injection magnesium and serum potassium levels tended to fall unless they were supplanted with potassium. There were seven patients who retained more than 20 mEq of the infused magnesium. Multifocal atrial tachycardia was successfully converted to sinus rhythm or sinus tachycardia in seven patients. Multifocal atrial rhythm (at slow rate) persisted in one patient. Two patients with falling serum potassium levels required potassium supplements. Results of this study confirm that patients with multifocal atrial tachycardia respond favorably to parenteral magnesium and potassium. We believe that serum magnesium administered together with serum potassium stabilizes the lonic balance of atrial cells and thus prevents spontaneous ectopy.

1685 BRAIN OXIDATIVE METABOLISM IN A SEVERELY ASPHYXIATED NEWBORN

Sequential in-vivo measurements of phosphorus-containing compounds by 31-P nuclear magnetic resonance (NMR) were obtained in a 2360 g, 36 wk gestation, meconium-stained infant born by vacuum extraction following 2 hrs of maternal fever and fetal tachycardia. Apgars were 1 at 1 min and 3 at 5 min. The infant was intubated, suctioned, ventilated, and given bicarbonate. Initial arterial blood gas was pH=7.16, PO2=43.6, PCO2=30, HCO3=10. Seizures noted at < 24 hrs were treated with phenobarbital. Cultures and cranial ultrasound were normal. EEC showed depressed, disorganized electrical activity but no epileptiform focus. The neurologic exam was remarkable for hypertonia, irritability, decreased activity, and posturing. NMR spectra obtained on 7 occasions between days 3-24 showed a sustained phosphocreatine/inorganic phosphate (PCr/Pi) < 1.0, due primarily to an abnormally high Pi, was markedly lower than PCr/Pi in normal infants (mean 1.07, range .76 - 1.49). PCr/Pi, a measure of phosphoenergetic reserve, was consistently 0.5 in the left hemisphere and increased from 0.5 to 0.9 over the 21 days of observation in the right. At day 23, the left hemisphere showed ½ the ATP of the right. These levels cause activation of glycolysis, acidosis, and further deterioration of the energy state and consequent cell disintegration. These data suggest there was an increased breakdown ol ATP and PCr to inorganic phosphate, as previously seen in areas of prenecrotic brain tissue in experimental animal models, and are much lower than those found in any surviving normal infants or animal models.

STATUS ASTHMATICUS

A retrospective analysis of 811 patients admitted to the hospital for status asthmaticus over a nine-year period was performed. Eight patients died, and 19 required mechanical ventilation. All persons who died of status asthmaticus were in the group that required mechanical ventilation. In 12 of the patients who received ventilation, no definite cause for the acute exacerbation could be identified, although initial arterial blood gas analyses showed profound hypoxemia, hypercapnia, and acute respiratory acidosis. Seventy-eight major complications occurred during mechanical ventilation. Pneumothorax, endotracheal tube malfunction, alveolar hypoventilation on the ventilator, and pneumonia were associated with decreased survival. Mucous plugging of the airways was found in all autopsied patients. Mechanical ventilation in status asthmaticus is a life-support system associated with substantial morbidity and should be instituted only when it becomes evident that maximal medical therapy will not be efficacious. (JAMA238:1158-1162, 1977)

Status Asthmaticus

A retrospective analysis of 811 patients admitted to the hospital for status asthmaticus over a nine-year period was performed. Eight patients died, and 19 required mechanical ventilation. All persons who died of status asthmaticus were in the group that required mechanical ventilation. In 12 of the patients who received ventilation, no definite cause for the acute exacerbation could be identified, although initial arterial blood gas analyses showed profound hypoxemia, hypercapnia, and acute respiratory acidosis. Seventy-eight major complications occurred during mechanical ventilation. Pneumothorax, endotracheal tube malfunction, alveolar hypoventilation on the ventilator, and pneumonia were associated with decreased survival. Mucous plugging of the airways was found in all autopsied patients. Mechanical ventilation in status asthmaticus is a life-support system associated with substantial morbidity and should be instituted only when it becomes evident that maximal medical therapy will not be efficacious.