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Water intoxication: A complication of nebulization with nasal CPAP
July 1976 The J o u r n a l o f P E D I A T R I C S
113
Water intoxication." A complication of nebulization with nasal CPAP Warren N. Rosenfeld, M.D.,* Michael Linshaw, M.D., and Howard A. Fox, M.D., Kansas City, Kan.
W H I L E the use o f continous positive airway pressure has decreased the mortality and morbidity rates o f idiopathic respiratory distress syndrome, it has also introduced a growing list o f iatrogenic complications. Complications, such as p n e u m o t h o r a x and interstitial e m p h y s e m a are directly related to the use o f end expiratory pressure while others are specifically related to the m e t h o d o f C P A P delivery. Airway obstruction with endotracheal intubation, facial necrosis with masks, and nasal deformities with nasal prongs can be included in this latter group. Recently we have observed a patient who received therapy with nasal C P A P and who developed h y p o n a tremia as a direct result o f the technique employed. CASE REPORT
A 1,600-gm male infant (born at 31 weeks' gestation) developed severe IRDS that required early mechanical ventilation. During the first week, Fio2 0.50 and 9 cm H20 positive end expiratory pressure were required with a Bourns Respirator to maintain normal values of arterial pH and Pao< Although, the infant was weaned from respiratory support by the tenth day, he was managed with nasal CPAP to decrease his needs for high ambient oxygen. The patient was able to maintain normal values of blood gases with Fio~ 0.35 and 7 cm H~O CPAP. The method of nasal CPAP used was a modification of that described by Novogroder and colleagues. 1 Long nasal canulas in a "Y" adapter were connected to a Carden Continuous Positive Pressure Breathing Device (DUPACO Inc., San Marcos, Calif. 92069). Inspired gas of the desired Fio~ was obtained from a lowflow oxygen blender. This was warmed and humidified by passage through a Puritan All-Purpose Nebulizer (Model No. From the Division o f Newborn Medicine and Pediatric Nqphrology, Department of Pediatrics, University o f Kansas Medical Center. *Reprint address': Department of Pediatrics, University of. Kansas Medical Center, 39th & Rainbow Blvd., Kansas City, Kan. 66103.
1260555, 126056 Puritan-Bennett Corp., Kansas City, Mo. 64106) with immersion heater. A water trap was interposed between the nebulizer and Carden CPPB Device. The patient tolerated the CPAP well and although his clinical condition improved, he developed edema over the next 24 hours. Serum sodium concentration which had been normal for three previous days decreased from 137 mEq/1 to 128 mEq/1. The patient was receiving only intravenous fluids (5% dextrose in water with 4 mEq/kg of NaCl and 1.5 mEq/kg of KCI) at a rate of 100 ml/kg/day. The volume was decreased to 80 ml/kg/day. On the following day, serum sodium concentration was 127 mEq/1 and urine output was 74 ml/day. Urine osmolalities ranged from 57 to 301 mOsm/1. Fluid was further restricted to 40 ml/kg/day of 5% dextrose in water with 6 mEq/kg of NaC1 and 3 mEq/kg of KC1. On the third day of therapy with nasal CPAP, despite a urine output of 127 ml/day, the serum sodium concentration was 126 mEq/1. Abbreviations used CPAP: continuous positive airway pressure IRDS: idiopathic respiratory distress syndrome
Since the hyponatremia failed to respond to fluid restriction the possibility of an exogenous water load delivered by the CPAP apparatus was investigated. Over a four-hour period the volumes of water collected from the water trap and the exhaust outlet of the Carden Valve were subtracted from the volume of fluid required to restore the nebulizer to its original level. At the flow rate of 11 liters/minute, required to maintain CPAP at 7 cm H20, 265 ml of water was lost from the nebulizer and 72 ml collected from the trap and valve, yielding a net volume difference of 193 ml or 48 ml/hour. While some portion of this volume was doubtless removed by routine hypopharyngeal suctioning; a portion can be assumed to have condensed in the hypopharynx and to have been swallowed by the infant thus providing the exogenous water source. The nebulizer stem was then removed from the Puritan Nebulizer, converting it to a simple warmer-humidifier. Water
Vol. 89, No. 1, pp. 113-114
1 14
Rosenfeld, Linshaw, and Fox
loss was again calculated over four-hour intervals at the same flow rate. In this configuration the net volume difference decreased to 15 ml/hour. With continued fluid restriction and removal of the nebulizer stem, the sodium increased to 131 mEq/ 1 in 48 hours. The infant subsequently maintained normal serum sodium concentrations when intravenous fluids were increased to 100 ml/kg/24 hours. The patient's respiratory status continued to improve and all CPAP was discontinued by the eighteenth day of life. DISCUSSION Water intoxication with nebulization has not been described before except with ultrasonic nebulizers which produce water particles small enoug h to cross the pulmonary surface? In descriptions of various methods of CPAP administration, 3' 4 humidification and warming of inspired gas was provided by a Puritan-Bennett Nebulizer similar to the one employed in this report and water intoxication was not described. Since the technique employed here delivers large quantities of warm, saturated air directly to the posterior pharynx, the potential exists for precipitation of moisture in the pharynx. This water can subsequently be swallowed and absorbed through the gastrointestinal tract. The water load delivered continuously by the nasal
The Journal of Pediatrics July 1976
CPAP apparatus would be expected to result in a marked diureses since premature infants have been shown to have an efficient diluting mechanism by two weeks of a g e ) Failure of a diuresis in this infant suggests that in addition to water overload other mechanisms, such as an altered response of antidiuretic hormone during hyponatremia, might have occurred. It is evident, however, that the exogenous water load was of major importance in tfiis infant since electrolyte balance was restored only after the nebulizer stem was removed. REFERENCES 1. Novagroder M, Mac Kuanying N, Eidelman A, and Gartner L: Nasopharyngeal ventilation in respiratory distress syndrome, J PEmAT~ 82:1059, 1973. 2. Kattwinkel J, Fleming D, Cha C, Fanaroff A, and Klaus M: A device for administration of continous positive airway pressure by the nasal route, Pediatrics 82:131, 1973. 3. Gregory G: Respiratory care of newborn infants, Pediatr Clin North Am 19:2, 311, 1972. 4. Graft T, and Benson D: Systemic and pulmonary changes with inhaled humid atmospheres, Anesthesiology 30:199, 1969. 5. Ames RG: Urinary water excretion and neurohypophysial function in full term and premature infants shortly after birth, Pediatrics 12:272, 1953.
113
Water intoxication." A complication of nebulization with nasal CPAP Warren N. Rosenfeld, M.D.,* Michael Linshaw, M.D., and Howard A. Fox, M.D., Kansas City, Kan.
W H I L E the use o f continous positive airway pressure has decreased the mortality and morbidity rates o f idiopathic respiratory distress syndrome, it has also introduced a growing list o f iatrogenic complications. Complications, such as p n e u m o t h o r a x and interstitial e m p h y s e m a are directly related to the use o f end expiratory pressure while others are specifically related to the m e t h o d o f C P A P delivery. Airway obstruction with endotracheal intubation, facial necrosis with masks, and nasal deformities with nasal prongs can be included in this latter group. Recently we have observed a patient who received therapy with nasal C P A P and who developed h y p o n a tremia as a direct result o f the technique employed. CASE REPORT
A 1,600-gm male infant (born at 31 weeks' gestation) developed severe IRDS that required early mechanical ventilation. During the first week, Fio2 0.50 and 9 cm H20 positive end expiratory pressure were required with a Bourns Respirator to maintain normal values of arterial pH and Pao< Although, the infant was weaned from respiratory support by the tenth day, he was managed with nasal CPAP to decrease his needs for high ambient oxygen. The patient was able to maintain normal values of blood gases with Fio~ 0.35 and 7 cm H~O CPAP. The method of nasal CPAP used was a modification of that described by Novogroder and colleagues. 1 Long nasal canulas in a "Y" adapter were connected to a Carden Continuous Positive Pressure Breathing Device (DUPACO Inc., San Marcos, Calif. 92069). Inspired gas of the desired Fio~ was obtained from a lowflow oxygen blender. This was warmed and humidified by passage through a Puritan All-Purpose Nebulizer (Model No. From the Division o f Newborn Medicine and Pediatric Nqphrology, Department of Pediatrics, University o f Kansas Medical Center. *Reprint address': Department of Pediatrics, University of. Kansas Medical Center, 39th & Rainbow Blvd., Kansas City, Kan. 66103.
1260555, 126056 Puritan-Bennett Corp., Kansas City, Mo. 64106) with immersion heater. A water trap was interposed between the nebulizer and Carden CPPB Device. The patient tolerated the CPAP well and although his clinical condition improved, he developed edema over the next 24 hours. Serum sodium concentration which had been normal for three previous days decreased from 137 mEq/1 to 128 mEq/1. The patient was receiving only intravenous fluids (5% dextrose in water with 4 mEq/kg of NaCl and 1.5 mEq/kg of KCI) at a rate of 100 ml/kg/day. The volume was decreased to 80 ml/kg/day. On the following day, serum sodium concentration was 127 mEq/1 and urine output was 74 ml/day. Urine osmolalities ranged from 57 to 301 mOsm/1. Fluid was further restricted to 40 ml/kg/day of 5% dextrose in water with 6 mEq/kg of NaC1 and 3 mEq/kg of KC1. On the third day of therapy with nasal CPAP, despite a urine output of 127 ml/day, the serum sodium concentration was 126 mEq/1. Abbreviations used CPAP: continuous positive airway pressure IRDS: idiopathic respiratory distress syndrome
Since the hyponatremia failed to respond to fluid restriction the possibility of an exogenous water load delivered by the CPAP apparatus was investigated. Over a four-hour period the volumes of water collected from the water trap and the exhaust outlet of the Carden Valve were subtracted from the volume of fluid required to restore the nebulizer to its original level. At the flow rate of 11 liters/minute, required to maintain CPAP at 7 cm H20, 265 ml of water was lost from the nebulizer and 72 ml collected from the trap and valve, yielding a net volume difference of 193 ml or 48 ml/hour. While some portion of this volume was doubtless removed by routine hypopharyngeal suctioning; a portion can be assumed to have condensed in the hypopharynx and to have been swallowed by the infant thus providing the exogenous water source. The nebulizer stem was then removed from the Puritan Nebulizer, converting it to a simple warmer-humidifier. Water
Vol. 89, No. 1, pp. 113-114
1 14
Rosenfeld, Linshaw, and Fox
loss was again calculated over four-hour intervals at the same flow rate. In this configuration the net volume difference decreased to 15 ml/hour. With continued fluid restriction and removal of the nebulizer stem, the sodium increased to 131 mEq/ 1 in 48 hours. The infant subsequently maintained normal serum sodium concentrations when intravenous fluids were increased to 100 ml/kg/24 hours. The patient's respiratory status continued to improve and all CPAP was discontinued by the eighteenth day of life. DISCUSSION Water intoxication with nebulization has not been described before except with ultrasonic nebulizers which produce water particles small enoug h to cross the pulmonary surface? In descriptions of various methods of CPAP administration, 3' 4 humidification and warming of inspired gas was provided by a Puritan-Bennett Nebulizer similar to the one employed in this report and water intoxication was not described. Since the technique employed here delivers large quantities of warm, saturated air directly to the posterior pharynx, the potential exists for precipitation of moisture in the pharynx. This water can subsequently be swallowed and absorbed through the gastrointestinal tract. The water load delivered continuously by the nasal
The Journal of Pediatrics July 1976
CPAP apparatus would be expected to result in a marked diureses since premature infants have been shown to have an efficient diluting mechanism by two weeks of a g e ) Failure of a diuresis in this infant suggests that in addition to water overload other mechanisms, such as an altered response of antidiuretic hormone during hyponatremia, might have occurred. It is evident, however, that the exogenous water load was of major importance in tfiis infant since electrolyte balance was restored only after the nebulizer stem was removed. REFERENCES 1. Novagroder M, Mac Kuanying N, Eidelman A, and Gartner L: Nasopharyngeal ventilation in respiratory distress syndrome, J PEmAT~ 82:1059, 1973. 2. Kattwinkel J, Fleming D, Cha C, Fanaroff A, and Klaus M: A device for administration of continous positive airway pressure by the nasal route, Pediatrics 82:131, 1973. 3. Gregory G: Respiratory care of newborn infants, Pediatr Clin North Am 19:2, 311, 1972. 4. Graft T, and Benson D: Systemic and pulmonary changes with inhaled humid atmospheres, Anesthesiology 30:199, 1969. 5. Ames RG: Urinary water excretion and neurohypophysial function in full term and premature infants shortly after birth, Pediatrics 12:272, 1953.