Annals of Burns and Fire Disasters - vol. XIII - n° 1 - March 2000

Napoli B.,¹ D'Arpa N.,¹ Masellis M.,¹ Graziano R.²

¹ Divisione di Chirurgia Plastica e Terapia delle Ustioni, Ospedale Civico, Palermo, Italy
² Divisione Ostetricia e Ginecologia, Ospedale Civico, Palermo

SUMMARY. Two cases are reported of bums in pregnancy. After a survey of the literature and a discussion of the incidence of bums in pregnancy, the physiopathology of spontaneous uterine activity is considered together with aspects of the treatment of bums and obstetric management in relation to maternal and foetal prognosis.

Texts on obstetrics do not deal with bums in pregnancy nor is the topic considered in books devoted to the treatment of bums. Tables I and II present the authors and cases present in the literature in papers, covering the problem.

Besides the description of individual cases or limited series of cases collected over protracted periods, we find works based on case histories from various bums centres. Matthews discusses 50 cases based partly on a questionnaire sent to all bums centres in the UK (16 cases) and partly on the previous literature (34 cases), and provides data regarding works by Sismondi et al., Yingbei Z. et al., and Stilwell; his work thus presents an almost complete survey of the literature up to 1982.

The characteristics of later papers untilthe present day are however no different. Raybum et al. report 30 cases studied over an 18-yr period in three American university bums centres; Arny et al. also describe 30 cases, 19 of which had however already described by Taylor et al. some years previously; Gang et al. reported 16 cases, half of which had already been presented by Srivastava et al. Cases previously described and collections of cases from other centres have contributed to the overall number of observations that have made it possible to establish the correct procedures to be observed as regards bums, i.e. in the mother, and as regards pregnancy, i.e. in the foetus, in relation to the stage of pregnancy. Before proceeding any further, however, a word of warning is necessary - Champagnie` published his case twice, while and Yingbei et al. published their 24 cases no fewer than three times.

The literature on bums in pregnancy is indeed limited, but the incidence of the phenomenon, as calculated by the various authors in relation to the total number of female burn patients of reproductive age, does not appear to be low, while the incidence in early pregnancy is unknown in the absence of routine pregnancy testing on admission. Apart from the 0.6% reported from Israel by Benmeir et al., Taylor et al. calculated an incidence of 7%, a rate also found by Amy et al.in later years (6.7%, Fort Houston), while the rate of 7.9% reported by Srivastava et al. was confirmed by Gang et al. (7.8%, Kuwait). The highest of all burn incidences in pregnancy was found in India, ranging from 7%, calculated by Akhtar (Nagpur), to 13.3%, reported by Jain (Bhilai), and 15% reported by Prasanna (Karnataka). This high incidence reflects the fact that of the 379 cases reported in the literature between 1958 and the present day that have come to our attention, 129 (34%) occurred in India (Tables I, II). In Italy only two cases have ever been reported in the literature (Sismondietal. and Caleffi et al.). We supplement these two cases and the international literature with two other cases that have come to our attention in recent years.

Case 1
De P.A., age 39 yr, first quarter pregnancy (4th week of amenorrhoea), suffered full-thickness skin burns in BSA 30% on 6 June 1994. On 25 August 1994 the patient was subjected in general anaesthesia to free skin graft and discharged on 13 September 1994. The patient originally opted for a voluntary abortion, which gave us a certain degree of freedom of action in the management of the pregnancy, but she later decided for religious reasons to carry the child to term. On 29 March 1995 she was delivered of a foetus presenting a serious cardiac malformation. The child died a few days after birth.

Case 2
R.I., age 20 yr,, third quarter pregnancy (33rd week of amenorrhoea), suffered full-thickness skin bums in 20% BSA on 28 December 1995. The treatment of the bums and the management of the pregnancy culminated in a surgical operation two weeks after the patient's admission. On 12 January 1996, after prophylaxis for hyaline membrane disease, the patient was subjected to a caesarian section. The foetus presented in podalic position (buttocks variety). The foetus, of female sex, weighed 2.4 kg and was alive and well, with Apgar 8 at minute 1 and 10 at minute 5. Immediately after closure of the abdominal wall, the patient was subjected to free skin graft in the burned areas (Figs. 1-3). On objective examination the baby showed nothing pathological in the various organs and systems but was kept in hospital in view of her prematurity. After a normal obstetric and surgical course the patient was dismissed on 23 January 1996.

Fig. 1 - Extraction of foetus. Fig. 2 - Patient after caesarian section. Fig. 3 - The living and viable foetus.

A. Thermal trauma and spontaneous uterine activity
The onset of labour in a premature delivery shortly after a serious burn was in the past thought to be triggered by the endocrine function, and in particular by that of the secretion of adrenocortical hormones related to stress.
Later observations confirmed that slight bums had no effect on the course of pregnancy, while bums of at least 35% TBSA were capable of provoking early labour and the loss of the foetus following intrauterine death within a week of the bum.
Both spontaneous miscarriage and premature delivery were subsequently thought to be related to the synthesis and release of prostaglandins (responsible for early uterine contractions) from the skin in the burn area. Later, however, the correct importance was attributed both to maternal shock, which determines a considerable reduction in the uterine blood flow and causes foetal hypoxia, and to pleuropulmonary complications, especially in cases of inhalation lesions with grave reduction of maternal P02 and consequently, as in this case, foetal hypoxia. Table III presents the events that as a result of foetal hypoxia and acidosis determine spontaneous uterine activity. The condition of hypotension and acute respiratory insufficiency is thus accompanied by septicaemia. This can lead to complications in the foetus, even some time after the bum, owing to the fact that the foetus may be able to tolerate the early phases of maternal sepsis but is notably affected in the advanced phases, when the mother is decompensated and her cardiovascular system collapses.

Table III - Events determining spontaneous uterine activity

As the maternal intravascular space is in a state of equilibrium with the amniotic liquid, the reduction of this liquid during serious hypovolaemia can cause the intrauterine death of the foetus. The onset of spontaneous uterine contractions is also favoured by the release from bacteria and the placenta of an enzyme, phospholipase A, which is necessary for the conversion of arachidonic acid into prostaglandin. It has recently been shown that there is a considerable reduction in plasma levels of 17B-oestradiol in pregnant burned women who had either an abortion or a still birth in the first week post-bum.

B. Burns treatment - its influence on the course of pregnancy and the foetus
Bl. General treatment.
Resuscitation treatment in the burned pregnant woman is no different from that in the nonpregnant burned woman. The prevention of hypovolaemic shock by adequate early fluid therefore requires that the uterine blood flow should be able maintain foetus tissue PO₂ levels within the normal range. It has been recommended that a quantity of fluid should be administered that is sufficient to maintain the mother's blood pressure within the normal range and a diuresis of 30-60 ml/h. The maintenance of arterial pressure levels at normal values is essential at all stages of the burn disease. Diuretics and anti-hypertension drugs should therefore be avoided whenever possible. Episodes of hypotension should be avoided also in the event of surgical operations. It is recommended that surgery should be performed with intraoperative maintenance of a minimum of 1 ml/kg/h of urine volume and 100% oxygen saturation.
Since extensive surface bums are frequently associated with an increased rate of arterial shunting and hypoxia, it becomes necessary to administer oxygen. A pregnant patient's oxygenation can often be improved by nursing her in a semi-sitting position. Maternal PO₂ values of less than 60 ram Hg during the pleuropulmonary complications that are often secondary to inhalation have been considered critical, and it has therefore been recommended that ventilatory support should be initiated as soon as possible. This is all the more necessary because inhaled carbon monoxide can also cross the placental barrier to compete for binding sites on foetal haemoglobin, provoking foetal cardiac oedema, and also affect cardiac development .If the respiratory complication is bronchopneumonia, it is necessary to use antibiotic treatment, if possible selecting drugs that the foetus can tolerate. The same applies to cases of suspected and manifest sepsis.

B2. Local treatment.
The local treatment of burns in pregnant women is not simple, because of the limitations imposed by the state of pregnancy. Chloramphenicol, either in powder form (Chemicetine) or as an ointment in association with collagenase (lruxol), is among the drugs to be avoided throughout pregnancy since it is teratogenous if administered during the first period of pregnancy and responsible for neonatal pathology if used during the final period (grey syndrome).
Gentamicin (Gentalyn cream, gentalyn ointment) is an aminoglycoside capable of passing through the placenta after absorption through bums. If used after the 14th week of pregnancy it can cause lesions in the 8th pair of cranial nerves, with vestibular and acoustic damage. The full-temi foetus has been found to present antibiotic concentrations analogous to those of the mother. In addition to ototoxicity aminoglycosides are responsible for nephrotoxicity.
Rifamycin SV (Rifocyn for local use) is absolutely to be avoided in the last period of pregnancy because its interference with bilimbin metabolism can cause indirect hyperbilirubinaemia, with the risk of kemicterus.
Sulpha drugs (silver sulphadiazine-Sofargen) are suspected of potential teratogenous activity if administered before the 14th week of pregnancy and of retarding growth, determining low birth weight if subsequently administered. Sulpha drugs administered at the term of pregnancy are responsible for kernicterus.
Salicylates (salicylate vaseline) exert an anti-prostaglandin action and may therefore have a protective effect on pregnancy. For the same reason they should not be used in the final period of pregnancy because they prolong gestation and delay spontaneous delivery. There is little evidence regarding the possibility that salicylates have a teratogenous effect, although the birth weight of babies born to women subjected to chronic administration of salicylates has been reported to be below average. An increase in perinatal mortality has also been reported. These results have not however been confirmed in other studies.
Povidone-iodine (lodoten) is widely used for bums cleansing. It must however be avoided in pregnant women since large amounts of iodine can be absorbed through the burn wound. Use of povidone-iodine is inadvisable in bums exceeding 20% TBSA because the iodine passing through the placenta can be absorbed in sufficient quantities to affect thyroid functions and cause metabolic acidosis.
It is thus clear that the state of pregnancy considerably reduces use of the commonest protocols for the topical treatment of burns. Even the local use of antibiotics that are normally administered systemically presents considerable difficulties. The only antibiotics that can be considered safe in pregnancy are the penicillins and cephalosporins, while vancomycin, one of the most frequently used and most active antistaphylococcal drugs, is considered to be potentially teratogenous and ciprophloxacin may possibly damage articular cartilages in undeveloped organisms.
Other commonly used antibiotics (Imipenem, teicoplanin) should be avoided in the absence of adequate information about their safety during pregnancy unless they are absolutely necessary and their advantages outweigh any possible risk.
These considerations are also valid with reference to the parenteral use of the above-mentioned drugs in the event of infective respiratory complications or sepsis. Tetracyclines are not widely used in bums but it should not be forgotten that they are contra-indicated during pregnancy because of their varying effects on foetal growth, bones, teeth, and the immune system.
With regard to local treatment, if the medication is performed under anaesthesia it is important to avoid the use of ketamine, which increases the excitability of the myometrium because it is capable of triggering effective contractions; also, when the pregnancy is near term and delivery is imminent, ketamine may cause respiratory depression in the neonate.

B3. Surgical treatment.
In view of the difficulties related to local medical treatment, early surgical therapy assumes vital importance. This is because early surgical facilitates healing of the wounds and thus improves prognosis in both mother and neonate. Early coverage of the bums also minimizes septic complications and the need to administer antibiotics; in addition, it reduces painful medications and the necessity of analgesic drugs.
The treatment comprises early tangential excision and split-thickness skin-grafting 3-7 days post-buni in the deeper burned areas (but not more than 15-20% TBSA at one operation). Wounds over the abdomen and breast have to be treated first. Good early healing of the abdominal wound favours:

• pain-free stretching of the abdominal skin during the developing pregnancy to term
• abdominal obstetric supervision of the growing foetus
• performance of caesarian section if required

Early surgery of the breast wound prevents infection and sloughing of nipples and permits subsequent breast feeding.

C. Obstetric management of the pregnant woman with burns
If it is known that a burned female is pregnant, it is important to establish as precisely as possible the exact stage of pregnancy at the time of the burn accident. This must be based upon the menstrual history and foetal ultrasound examination. The gestational period is in fact one of the factors determining obstetric procedures (no intervention, protection of pregnancy by tocolithic treatment, induction and/or acceleration of labour). Other factors are the severity of the burn and foetal viability, which must be confirmed immediately. Such biophysical measurements as foetal muscle tone, limb motion and breathing patterns, placental morphology, and amniotic fluid volume may be visualized in order to assess foetal health.
With regard to the stage of gestation, foetuses delivered before 24 weeks generally will not survive, while those delivered after 32 weeks will do well with modem neonatal intensive care if born without hypoxia or birth trauma. The most difficult to manage are foetuses of between 24 and 32 weeks' gestational age, where ex utero survival is difficult to predict. In such cases, therefore, when pre-term labour occurs, tocolysis procedures are initiated.
In the light of the findings of Ryan et al. (relative to two patients with respectively 65% and 70% TBSA bums presenting first-quarter pregnancy who survived and had full-term deliveries), it was long believed that pregnancy improved prognosis in the mother. However, the findings of Matthews indicated that a more advanced state of pregnancy (2nd-3rd quarter) in women with over 50% TBSA bums had an unfavourable effect unless delivery was immediate, as the burn created an unfavourable environment for the foetus; in bums in less than 40% TBSA pregnancy and its continuation had no effect on prognosis in the mother and every attempt had to be made to interrupt inception of labour if the foetus was too immature to survive.
Table IV presents a protocol that has recently been proposed. Its presenters do not suggest that the protocol should be applied rigidly in all cases but rather that it should be regarded as a useful general guideline.

Regarding the manner of delivery (vaginal route, caesarian section), spontaneous vaginal delivery is generally preferred, although obstetric considerations affect the choice of route and the timing of the delivery; serial foetal sonography and electronic heart rate monitoring, by means of cardiotocographic recording, identifies foetal stress at an early stage and may permit timely intervention, preventing intrauterine death. In a critically burned woman with a living and near-term pregnancy, foetal salvage by caesarian section appears justifiable.
When there are obstetric indications for a caesarian section, this can be performed even when the lower abdominal wall is part of the burned area.

Conclusion

Although the relevant literature is limited, the incidence of bums in pregnancy does not appear to be low, especially in developing countries such as India where bums constitute a social disease.
As hypovolaemia causes a reduction in uterine blood flow and in the amniotic fluid, the overcoming of maternal shock is of fundamental importance for foetal prognosis. At a later stage the drop in pressure related to septic episodes and the reduction of maternal PO₂ secondary to pulmonary complications. Hypovolaemia and hypoxia are in fact the cause of the spontaneous uterine contractions that lead to abortion or premature delivery after intrauterine death of the foetus. An important role is played by the synthesis and release of prostaglandin both by the burned skin and as a result of dehydration, if not appropriately corrected.
The general and topical treatment of bums in the pregnant woman has to take into account the embryonal, foetal, and perinatal toxicity of the pharmacological therapy employed, since what is beneficial for the mother may be harmful for the child. Particularly difficult therapeutic courses have been found to cause serious malformations; and even the infusion of hypertonic glucose solutions can lead to secondary hyperinsulaemia with foetal macrosornia.
In order to reduce pharmacological therapy to the minimum possible and to accelerate the burn healing process (and thus improve prognosis), the majority of authors are favourable to early surgical intervention. Obstetric management of pregnancy in the burned woman requires:

• monitoring of the pregnancy by frequent ultrasound scanning, daily measuring of the blood clotting factor, and, where possible, cardiotocographic monitoring. Intrauterine death of the foetus may be preceded by a reduction of 178-oestradiol and E, levels;
• calculation of the stage of gestation and the gravity of the burn; obstetric treatment must be P-Aated to these two parameters
• choice of method of delivery (vaginal route, caesarian section).

RESUME. Les Auteurs décrivent deux cas de brûlures pendant la grossesse. Après avoir examiné la littérature relative et discuté l'incidence du phénomène, ils approfondissent la physiopathologie de l'activité utérine spontanée et les aspects qui concernent soit le traitement des brûlures soit la gestion obstétricale en fonction du pronostic maternofétale.

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