Archives ofDisease in Childhood 1990; 65: 1259-1262

1259

Air leaks and vasopressin release N McIntosh, P Prakash, A Smith

Abstract Eleven very low birthweight babies being ventilated for respiratory problems during the first week of life developed air leaks on 22 occasions. On 16 out of 19 occasions the infants showed increases in urinary excretion of vasopressin after these events and on 10 occasions out of 13 there was a rise in the plasma arginine vasopressin concentration. The peripheral signs of the syndrome of inappropriate antidiuretic hormone release were seen on only one occasion in response to the sometimes high vasopressin concentrations.

Department of Child Health, St George's Hospital Medical School, London N McIntosh P Prakash A Smith Correspondence to: Professor N McIntosh, Deartnment of Child Life

and Health,

17 Hatton Place, Edinburgh EH9 IUW. Accepted 10 May 1990

(by flame photometry), and the arginine vasopressin concentration, and the values before and after the air leak were compared (table 1). Samples of plasma were taken eight hourly for measurements of osmolality and creatinine, urea, electrolyte, and plasma vasopressin concentrations. All 11 infants had severe respiratory distress syndrome and were ventilated by Bourns BP200 ventilators using standard techniques. Continuous blood pressure monitoring and transcutaneous blood gas monitoring allowed one hourly values of systolic, diastolic, and mean blood pressures and transcutaneous oxygen and carbon dioxide tensions to be averaged for the eight hours before and after the development of the air leak. Intermittent sampAir leaks are common in infants who require ling of arterial blood gases was carried out, ventilation for respiratory problems in the first usually at intervals of three to four hours. Acid week of life. In this unit the overall incidence base values eight hours before and after the air has been 32%, and for infants weighing less leak were similarly assessed. The babies were than 1000 g at birth it has been 44%, during a weighed daily (usually between 4 and 6 am) and six year period. Management of fluid balance is plasma and urinary vasopressin concentrations also difficult in these infants. The reports of were measured by specific radioimmunoassay.7 release of the antidiuretic hormone, arginine The study was approved by the St George's vasopressin, together with the development of Hospital medical ethics committee. air leaks" might indicate that fluid intake should be reduced after such events as is done after birth asphyxia.5 We have evaluated 11 very Results low birthweight infants who developed air leaks The results are shown in tables 1 and 2. to determine the extent to which vasopressin release occurs and to identify features sugges- PLASMA CREATININE tive of consequent fluid retention. The plasma creatinine values at the time of the development of the air leak are shown in table 1. The mean concentration (103 [unol/l) is within Patients and methods the normal newborn reference range but infants Eleven very low birthweight infants (mean (SD) 3, 9, 10, and 11 have values above the upper birth weight 1073 (298) g, mean (SD) gestation limit of this range (>120 ,umol/l) indicating a 27-6 (2 0) weeks) who had been included in a degree of renal failure, though three of these study to examine the control of water balance in infants later had values within the reference the respiratory distress syndrome developed air range. leaks (pneumothorax either alone:n=7, or combined with pulmonary interstitial emphysema: AND URINARY OSMOLALITIES n=3). A single infant developed pulmonary PLASMA There was no significant difference (paired t interstitial emphysema alone. between the plasma or urinary osmolalities test) The infants were all nursed in air mode before and after the air leaks. At both times controlled incubators that were humidified if the plasma osmolalities were high (mean (SD) the infants weighed less than 1000 g (n=5). before 299 (12) and after 306 (13)). The variable Fluid intake was standard with final adjust- urine osmolalities are shown in table 1. There ments on clinical grounds by the attending no correlation between the change in the clinician depending on weight, electrolyte con- was or plasma osmolalities and the change in centrations, and urine volumes. Urine was urinary the excretion before and arginine of Liu collected four hourly by the method and after the air vasopressin leak. Anderson,6 and the volume in the eight hours before the development of the air leak was compared with the volume passed in the following PLASMA ARGININE VASOPRESSIN eight hours. In each four hour specimen the CONCENTRATION (FIG 1) following were measured: osmolality (by freez- The plasma concentrations of arginine vasoing point depression), the sodium concentration pressin increased after 10 of the 13 air leaks.

McIntosh, Prakash, Smith

1260

Table I Biochemical values in II infants before and after developing 22 air leaks correlated with urinary arginine vasopressin

PT

1

46 68 98 117 117 149 95 103 (urea 82) (urea72) 111 111 91 76 110 110 149 130 93 130 83 89 103 (26)

PT PT PT PT PT PT PT PT PT PIE PT PIE PT PIE PIE+PT PT PT PT PT PT PT

2 3

4 5 6 7

8 9 10 11

Mean (SD)

After

Difference Before

84 405 387 338 512 177

155 213 175 387 425 398 313 191

+9 -47 +91 -18 +38 +60 -200 +14

-

-

-

210 386 392 182 178

386 340 413

+176 -46 +21

Before

After

Difference Before

228 302

316

+28 -

146 260

-

306 322 322 308 308 310 302 273 303

-

-

307 307 309 309 290 292 277 304 303 313 318 278

+15 +15 -1 -1 +20 +10 -4 -1

-

+5 -19

318 299

-

286 298 313 298 288 308 299 (12)

-

-

-

-

195

246 360

-

-

-

-

269 182 241 571 553 384 250 416 450 301 (132) 320 (116)

-

-97 -

-18 -134 +34

t=-0 33

t=-1-55 (p=02)

Paired t test

+68 +165

-

-10 288 +16 304 312 +4 306 (13)

14 5 15 14 8-5 (ic) 30 14 40 28 35 7 (ic) 17 27 38 17 21 9(ic) 32 42 11 28 37 23 (11)

Corelations between differences

After

Difference

Before

After

Difference

14 7 7 7 (ic) 9-1 20 9 21 29 16 (ic) 48 32 28 30 21 27 (ic) 17

0 +2 -8 -10 -5 -19 +1 +15 +1 -8 +4 +6

17 51 21 70 64 126 11 42 44 149 58 114 114 76 40 51 18 19 42 144 88 157 73 (45)

23 11 26 64 52 137 121 48 58 139 114 125 119 33 61 145

+6 -40 +5 -6 -8 +11 +10 +6 +14 -10 +56 +11 +5 -43 +21 +96

(ic) 12 14 18 19 (8')

-

-15 +1 -14 -19

1 1 2-5 51 134 127 1 9 40 136 324 22 24 25 112 3 5 6 191 189 24

-

-

27 152 35 169 83 (52)

Before After Difference

+8 +8 -55 +12

r= -0-45

0 1 4 5 2-2 -1 56 +4 -

233 610 1 7 440 324 222 48 99 112 2054 27 4-8 9 397 13 605

+99

+490 0 -2 +400 +178 -102 +26 +75 +87 +1990 +24 -0-2 +3 +208 -176 +577

(Wilcoxon'ssigned pair test, p0 1

r=+0-4

p=0 9 -r=+0-69 p

Air leaks and vasopressin release.

Eleven very low birthweight babies being ventilated for respiratory problems during the first week of life developed air leaks on 22 occasions. On 16 ...
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