Managing Medical and Obstetric Emergencies and Trauma. Группа авторов

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СКАЧАТЬ pale, sweaty, cyanosed skin with delayed capillary refill

       Alteration of mental state

       Tachypnoea

       Fall in urine output

       Narrowed pulse pressure

       Hypotension (late sign)

       Increase in heart rate

      An increase in the heart rate occurs in compensation for hypovolaemia (1000–1500 ml blood loss) or vasodilatation, both of which can cause hypotension and shock. A maternal heart rate of more than 100 beats/min should be considered sinister, until proven otherwise. Most, but not all, women will become tachycardic if bleeding significantly, but paradoxical bradycardia also occurs. Vagal stimulation caused by cervical stimulation (e.g. products in the os) or peritoneal irritation can produce bradycardia profound enough to cause shock. Medications such a beta‐blockers and labetalol (alpha‐ and beta‐blocker) will prevent a tachycardic response to hypovolaemia and this may be falsely reassuring in the assessment of the bleeding patient.

       Skin, capillary refill, mental state and urine output

      The skin, kidneys and brain can be thought of as ‘end organs’ that reflect the adequacy of perfusion to tissues.

       Capillary refill time (CRT)

      This is an indication of skin perfusion. It can be assessed by compressing a fingernail, or pressing on the sternum, for 5 seconds. The test is normal if colour returns within 2 seconds of releasing compression (i.e. a CRT of less than 2 seconds – the time taken to say the words ‘capillary refill’). If the patient is in a cold environment, CRT, especially peripherally, will be unreliable.

       Mental state

      If the woman is conscious and talking sensibly, she is not only breathing through an open airway, she is perfusing her cerebral cortex with sufficient oxygenated blood (50% of the normal cardiac output). Increasing hypovolaemia and subsequent cerebral hypoperfusion cause alterations in the level of consciousness. These alterations may begin with agitation and, if untreated, may proceed through confusion and aggression to eventual unresponsiveness and death.

       Narrowed pulse pressure

      This is caused by an increase in diastolic blood pressure, that reflects vasoconstriction occurring due to endogenous catecholamine release as a compensation for hypovolaemia.

       Systolic hypotension

      The sign most commonly referred to in the context of shock, hypotension, is a very late sign in the obstetric population, developing only when significant blood loss has occurred. A successful outcome for the patient depends on the early recognition of shock, restoration of volume and control of haemorrhage.

      Recognition of hypovolaemia

Maternal blood loss can be categorised into four classes of severity, as shown in Table 6.1 and graphically in Figure 6.2.

      To remember the different percentages in these classes of blood loss, think of the way of scoring in a tennis match!

      Figure 6.2 illustrates the various clinical signs seen in ongoing acute blood loss suffered by a pregnant woman related to the volume lost. The point where the pulse rate is a higher number than the systolic blood pressure is a sign of significant decompensation.

Table 6.1 Severity of blood loss during maternal haemorrhage

Class	Loss of circulating volume (%)	Blood loss in a 70 kg pregnant woman (ml)	Signs and symptoms
I	0–15	<1000	Fully compensated due to blood diversion from the splanchnic pool. No symptoms. Minimal tachycardia is likely to be the only abnormal sign. No treatment needed in an otherwise healthy woman as long as the bleeding has stopped
II	15–30	1000–2000	Peripheral vasoconstriction maintains systolic blood pressure. The woman may be aware of increased heart rate and may display agitation or aggression. Narrowed pulse pressure and tachypnoea are the keys to early detection, as heart rate is only modestly increased and systolic blood pressure remains normal. Peripheral vasoconstriction maintains blood pressure. Requires crystalloid fluid replacement
III	30–40	2000–2700	Cardiovascular system shows signs of decompensation. The woman will look unwell. Tachycardia, tachypnoea, changes in mental status, fall in systolic blood pressure. Will require crystalloid and potential blood transfusion
IV	>40	>2700	Immediately life threatening. Tachycardia, fall in blood pressure, altered mental status, evidence of negligible urine output. Loss of >50% results in loss of consciousness, requiring immediate ‐surgery as well as massive transfusion

Figure 6.2 Clinical parameters following increasing blood loss in the pregnant and postpartum woman

       Pitfalls in the recognition of shock in pregnancy

       Some pregnant women do not mount a tachycardia, or can even produce a bradycardia. This can be paradoxical, due to vagal stimulation [see above] or if the woman is taking beta‐blocker medication

       Women with pacemakers have a fixed upper heart rate

       Athletes may have a very slow baseline heart rate

       Haemoglobin concentration is a useful measure of blood loss, only after there has been fluid resuscitation

During the acute phases of loss, the haemoglobin concentration will not change. Rapid movement of fluid from the extracellular to the intravascular compartment and intravenous clear fluids, will result in a fall in haematocrit. A falling haematocrit may be the only indicator of a slow steady bleed. СКАЧАТЬ