Stephen Longmire

Role of intravenous nitroglycerin in the treatment of severe pregnancy-induced hypertension complicated by pulmonary edema

Intravenous nitroglycerin would appear to be an ideal agent for the treatment of severe pregnancy-induced hypertension complicated by cardiogenic pulmonary edema. Nitroglycerin infusion effectively reduces preload by venous dilatation and, at higher doses, results in arterial vasodilatation. Because of these pharmacologic properties, the effects of intravenous nitroglycerin were studied in three patients with severe pregnancy-induced hypertension complicated by pulmonary edema. The major cardiovascular effects of nitroglycerin were to reduce the mean pulmonary capillary wedge pressure from 27 +/- 4 to 14 +/- 6 mm Hg, which result in a change in the colloid osmotic pressure to pulmonary capillary wedge pressure gradient from -10 to 2 mm Hg. No significant changes occurred in heart rate, central venous pressure, or cardiac index. Analysis of oxygen-related parameters revealed a significant (p less than 0.05) increase in oxygen delivery and extraction accompanied by a 53% increase in oxygen consumption. The changes in oxygen-related variables appeared to be secondary to a fall in mixed venous oxygen tension from 39 +/- 4 to 33 +/- 1 torr. These changes occurred without any significant improvement in arterial oxygen tension. We conclude that while intravenous nitroglycerin expeditiously corrects the hydrostatic derangements of pulmonary edema seen in pregnancy-induced hypertension, a rapid improvement in arterial oxygenation does not occur.

Alfentanil for urgent Caesarean section in a patient with severe mitral stenosis and pul-monary hypertension

We present the case of a parturient with severe mitral stenosis and pulmonary hypertension who received general anaesthesia using alfentanil for urgent Caesarean section. Alfentanil promoted haemodynamic stability and allowed immediate postoperative extubation. Epidural morphine provided postoperative analgesia. This combination permitted early ambulation and prevention of thromboembolism. A disadvantage of this technique, neontal respiratory depression, was promptly reversed with a single dose ofnaloxone. The anaesthetic management of mitral stenosis in pregnancy is discussed and the neonatal pharmacokinetics of maternally administered alfentanil are presented.RésuméOn présente le cas d’une parturiente atteinte d’une sténose mitrale sévire et hypertension pulmonaire avant subi l’anesthésie générale avec de l’alfentanil pour une césarienne d’urgence. L’alfentanil a favorise la stabilité hémodynamique et a permis une extubation rapide. La morphine en administration épidurale afourni l’analgésie postopératoire. Cette combinaison a permis une mobilisation précoce et la prévention de l’embolie. Le désavantage de cette technique, la dépression respiratoire néonatale, a été rapidement antagonisé par une dose unique de naloxone. La conduite anesthésique de la grossesse chez les femmes atteintes d’une sténose mitrale est discutée et la pharmacocinétique néonatale et maternelle de l’alfentanil est présenée.

POST-CAESAREAN SECTION ANALGESIA : A COMPARISON OF EPIDURAL BUTORPHANOL AND MORPHINE

Epidural butorphanol 1, 2 and 4 mg were compared with morphine, 5 mg, for postoperative analgesia in 92 consenting, healthy, term parturients who had undergone Caesarean section under epidural lidocaine anaesthesia in a randomized double-blind study. Postoperative pain was assessed using a visual analogue scale and recorded with heart rate, blood pressure and respiratory rate. The demographic characteristics, and the incidences of primary and repeat Caesarean sections, were not different among the four treatment groups. At 15, 30, 45 and 60 min after treatment the median pain scores following butorphanol were similar and lower than those following morphine (P < 0.05). Calculated median percentage pain relief values for butorphanol were higher than morphine at each of these times (P < 0.05). At 90 min and 2 hr the pain scores and pain relief values were similar. Beyond 45 min the number of patients requesting supplemental medication and dropping out of the study increased progressively in both the butorphanol and morphine treated patients. The attrition profiles for butorphanol were different from morphine (P < 0.01). The median time in the study was > 24 hr for morphine, and 3, 2.5 and 4 hr for butorphanol, 1, 2 or 4 mg, respectively. No patient developed a clinically important change in heart rate or blood pressure, and none experienced a decrease in respiratory rate below 12 breaths · min−1. One of 69 patients (1.4 per cent) who received butorphanol developed pruritus compared with ten (43 per cent) of 23 patients who received morphine. The global assessments of the adequacy of analgesia were indistinguishable between morphine and butorphanol. Epidural butorphanol provides safe, effective postoperative analgesia, has a prompt onset, and a limited duration.RésuméDans une étude à double insu lors de césarienne chez 92 parturientes à terme, nous avons comparé l’efficacité de 1, 2 et 4 mg de butorphanol à celle de 5 mg de morphine injectés dans le cathéter employé pour l’anesthésie épidurale à la lidocaïne. Nous jaugions la douleur postopératoire sur une échelle visuelle analogue et mesurions le pouls, la tension artérielle et la fréquence respiratoire. Les variables démographiques et la proportion de césariennes itératives étaient semblables dans les quatre groupes. Les valeurs médianes d’intensité douloureuse 15, 30, 45 et 60 min après l’injection de butorphanol étaient les mêmes pour les trois doses et étaient inférieures à celle de la morphine (P < 0,05); en même temps, les pourcentages médians de soulagement étaient plus grands avec le butorphanol qu’avec la morphine (P < 0,05). Toutefois, à 90 min et 2 h post injection, ces variables étaient les mêmes pour les deux morphiniques. A partir de la 45ième minute, de plus en plus de patientes traitées à la morphine ou au butorphanol nécessitaient d’autres analgésiques, mettant ainsi un terme à leur participation à l’étude mais à une fréquence différente selon le morphinique (P < 0,01). La durée médiane de participation à l’étude était de plus de 24 h pour la morphine et de 3, 2,5 et 4 h pour les doses de 1, 2 et 4 mg de butorphanol respectivement. Il n’y eut pas de modification clinique du pouls ou de la tension artérielle non plus que de bradypnée à moins de 12 min−1. Une seule des 69 patientes (1,4 pour cent) ayant reçu du butorphanol se plaint de prurit mais 10 des 23 patientes (43 pour cent) du groupe morphine firent de même. L’évaluation globale de l’efficacité analgésique était la même pour la morphine et le butorphanol. Le butorphanol épidural offre une analgésie postopératoire sûre et efficace; il agit rapidement et pendant une période limitée.

The hemodynamic effects of intubation during nitroglycerin infusion in severe preeclampsia

The effectiveness of intravenous nitroglycerin infusion in lowering maternal blood pressure and in blunting the hemodynamic responses to endotracheal intubation was evaluated in six primigravid women with severe preeclampsia. Monitoring consisted of continuous electrocardiogram monitoring, arterial cannulation, and flow-directed pulmonary arterial catheterization in each patient. All patients underwent oxytocin induction of labor and crystalloid and/or colloid expansion to produce a pulmonary capillary wedge pressure of 10 to 15 mm Hg and a colloid osmotic pressure of greater than 17 mm Hg. Intravenous nitroglycerin was administered before induction of general anesthesia. The hemodynamic effects associated with endotracheal intubation revealed a change in the heart rate from 104 +/- 10 to 133 +/- 17 beats/min, an increase in mean arterial pressure from 134 +/- 12 to 164 +/- 32 mm Hg, and an increase in systemic vascular resistance from 1262 +/- 342 to 1351 +/- 259 dynes-sec-cm-5 that was accompanied by a small change in the cardiac index from 4.5 +/- 1.2 to 4.5 +/- 0.9 L.min-1.m-2.

Role of Volume Expansion in Severe Preeclampsia

Fifteen primigravid patients with severe pregnancy-induced hypertension were studied by catheterization of the right side of the heart. A hemodynamic protocol was implemented that required maintaining colloid osmotic pressure above 17 millimeters of mercury, pulmonary capillary wedge pressure below 15 millimeters of mercury and the mean arterial pressure in a very narrow range throughout labor and delivery and for 48 hours postpartum. The initial colloid osmotic pressures and pulmonary capillary wedge pressures were 18.0 +/- 2.6 and 10.5 +/- 4.0 millimeters of mercury, respectively, and remained essentially unchanged throughout the post partum period. The only benefit derived from volume expansion in these patients appeared to be the absence of acute fetal distress after the initiation of antihypertensive therapy. Six of 15 patients had late fetal stress develop during labor, suggesting that aggressive volume repletion and colloid osmotic pressure correction in pregnancy-induced hypertension does not effect the over-all incidence of fetal distress. We recommend that correction of colloid osmotic pressure be restricted to instances in which extremely low values (less than 12 millimeters of mercury) or a prolonged negative colloid osmotic pressure to pulmonary capillary wedge pressure gradient are identified. Finally, the benefit of volume expansion in pregnancy-induced hypertension appears to be the prevention of sudden and profound drops in blood pressure with antihypertensive therapy--not the prevention of fetal distress during labor.