Passive opening of the Eustachian tubes is the ideal and natural way to equalize pressure between the middle ear and the nasopharynx, although it is not always possible. Most amateur divers need to use an active technique, under their voluntary control, which will inflate the middle ears and prevent the pain and discomfort of barotrauma during descent. During ascent, passive equalization of ear pressures is more common, and active techniques are rarely needed.
Sometimes reluctant trainees use the failure to autoinflate ears as an acceptable excuse to avoid diving. Other times they are scared to use sufficient nasopharyngeal pressure for fear of causing damage.
It is part of the routine diving medical examination to ensure that the diving candidate can autoinflate the middle ear actively. This is achieved by using a positive pressure manoeuvre described to the diver while the examiner is observing the tympanic membrane and its movement with an otoscope. The latter is employed either by focusing on the light reflex or on another part of the tympanic membrane that reflects light (either the membrane flaccida or the circumference). As the candidate autoinflates the middle ear, the tympanic membrane moves outward.
Investigations using otoscopy and modified diving tympanometry (see Chapter 36) are reasonably reliable in predicting which candidates will have trouble resulting from Eustachian tube disorders. However, many divers fail because of an inadequate autoinflation and diving technique.
The following techniques for autoinflation are recommended. Different candidates perform them with varied ease. In each case, practice of the technique is recommended on land, before subjecting the novice to hyperbaric and aquatic conditions that interfere with the application of this new skill.
The Valsalva manoeuvre is probably the most easily understood. It involves occluding the nostrils, closing the mouth and exhaling so that the pressure in the nasopharynx is increased. This separates the cushions of the Eustachian tube and forces air up this tube into the middle ear. The pressure required to achieve this is usually 20 to 100 cm H2O.
Middle ear equalization answers to clients’ problems
- I descend a bit slower than my buddies. Or,
- If there is any pressure, I halt my descent and wait a bit. Or,
- I may ascend until the ear clears (yo-yo technique).
Answer: Why? If you are not equalizing the middle ear promptly or sufficiently, then these procedures merely allow the middle ear to fill with blood or tissue fluids and thus allow further descent with less pain or discomfort. This is not a sensible way to equalize the middle ear. It results in middle ear congestion, Eustachian tube obstruction and other disorders that may be temporary or permanent.
Client: I am trying to use swallowing to equalize the middle ear.
Answer: If you have any difficulty with middle ear equalization, then employing techniques that result in relatively negative middle ear pressures, cause middle ear congestion and Eustachian tube blockage. Use the positive pressure Valsalva technique (or Lowry or Edmonds techniques) before and during descents.
Client: I have middle ear equalization problems when I swim down the shot line.
Answer: This requires greater force to autoinflate the middle ear because you are trying to force air down the Eustachian tube. Descend feet first and you can blow air up the Eustachian tube. Air travels more easily up than down in the water. Remember bubbles? They rise.
Client: If there is any water in my ears (fullness, crackling) after the dive, I use alcohol ear drops to dry them out.
Answer: It is likely that the ‘water’ is really fluid in your middle ear from barotrauma. See earlier.
Client: I sometimes have a bit of blood from my nostril (or in my throat).
Answer: Although the blood may be from your sinus, following expansion of air with ascent, it is more likely from the middle ear on that side. In either case, correct middle ear equalization (‘ahead of the dive’) may well fix both. See earlier.
Client: When I dive and equalize the middle ear, I hear a squeaking sound in my ear.
Answer: This suggests a narrowed Eustachian tube, possibly from inadequate middle ear equalization and barotrauma. The sound you should hear when you equalize the middle ear and the ear drum moves outward is a click or pop. It takes a split second to achieve. It is not a long, drawn-out sound.
Client: I can often dive once, without problems, but cannot equalize the middle ear on other dives.
Answer: You have probably produced some middle ear congestion (barotrauma) in the first dive but continued the dive. By the second dive, you start off with significant middle ear congestion, and so middle ear equalization is more difficult.
Client: One ear equalizes before the other.
Answer: Not a problem. It is normal. You may wish to assist the slow ear by pointing it toward the surface as you equalize the middle ear.
The force necessary for successful autoinflation will vary with the diver’s body position. Using the Valsalva technique, novice divers average 40 cm H2O in the head-up, vertical position and in the horizontal ‘ear-up’ position. In the horizontal ‘ear-down’ position they need 50 cm H2O. In the vertical, swimming-down position they average about 60 cm H2O.
The Valsalva manoeuvre used by divers is modified from that employed originally by Antonio Valsalva to increase intrathoracic pressure. Trials performed on divers indicate that they do not produce the prolonged high thoracic pressures often encouraged by cardio-thoracic physiologists. With the latter, the problems induced by prolonged high Valsalva pressures include cardiac arrhythmias, hypertension and hypotension, arterial and venous haemorrhages, pulmonary and otological barotrauma, gastric reflux, stress incontinence and the possible shunting of blood through right-to-left vascular shunts (atrial septal defects and patent foramen ovale) thus increasing the possibility of paradoxical gas embolism with diving.
The Frenzel manoeuvre involves closing the mouth and nose, both externally and internally (this is achieved by closing of the glottis), and then contracting the muscles of the mouth and pharynx upward (‘lifting the Adam’s apple’). Thus, the nose, mouth and glottis are closed, and the elevated tongue can be used as a piston to compress the air trapped in the nasopharynx and force it up the Eustachian tube. Pressure of less than 10 cm H2O may accompany this manoeuvre.
As divers become more experienced, they tend to use such techniques as jaw movements, commencing a yawn, swallowing, lifting the soft palate and so forth, which allow for equalization of the middle ear without pressurizing the nasopharynx.
The Toynbee manoeuvre involves swallowing with the mouth and nose closed, and it is of value in relieving the overpressure in the middle ear during ascent. It is also of value during descent when movement of the Eustachian cushions produces a nasopharyngeal opening of the Eustachian tube, with an equalization of pressures between the nasopharynx and the middle ear. Thus, the final pressure in the middle ear with the Toynbee manoeuvre may be negative (less than environmental).
A combination of techniques has also been proposed. A very successful one is the combination of the Toynbee and Valsalva techniques, known as the Lowry technique. This involves occlusion of the nostrils, then a swallowing movement that is made continuous with a Valsalva manoeuvre. The diver is thus advised to ‘hold your nose, swallow and blow at the same time’. Despite the rather confusing (and impossible to achieve) instruction, the technique is extremely valuable in resistant cases. It is easily learned with practice, on land.
The Edmonds technique is rather similar and involves the opening of the Eustachian cushions by rocking the lower jaw forward and downward (similar to the start of a yawn) so that the lower teeth project well in advance of the upper teeth and performing the Valsalva manoeuvre at the same time.
The Edmonds number 2 technique is to advise the diver to ‘block your nose, close your mouth then suck your cheeks in, then puff them out – quickly’.
Soft palate contraction is a technique whereby the diver contracts and raises the soft palate, thereby moving the Eustachian cushions, occluding the nasopharynx and causing minimal elevation of the pressure within this space, opening the Eustachian tube and forcing air up the tube. It is sometimes called the béance tubaire voluntaire or BTV, and it is usually employed by experienced divers who have relatively patent Eustachian tubes and who, over the years, have developed this muscular skill. An interesting variation of the BTV is the Roydhouse technique. Here the diver is asked to identify the uvula hanging down from the posterior of the hard palate, then raising it as he or she moves the back of the tongue downward. This opens the Eustachian tubes, and the diver can verify it by hearing his or her own humming sounds reverberate in the ears.
When examining potential divers, attempts to demonstrate either the Frenzel technique or the BTV are not usually successful. In the author’s practice, during otoscopy, the Valsalva manoeuvre is tried first, followed by the Toynbee, the Lowry and then the Edmonds techniques. If there is any difficulty remaining with equalization, then the candidate is advised to repeat the most effective procedure a few times a day and achieve success, determined by hearing both ears click, before commencing diving.
Academic arguments abound as to which is the best technique. Whichever works is the best. The major problem is not the danger of middle ear autoinflation, but the dangers of not autoinflating.
Some techniques (Valsalva, Lowry, Edmonds) have the disadvantage of a transitory pressure that may extend into the thorax, but this is not usual with divers. These techniques have the advantage of distending the middle ear and thus allow further descent without the problems of a negative middle ear pressure developing and producing middle ear congestion and Eustachian tube obstruction. These techniques are therefore better for novice divers and for those who have trouble with middle ear autoinflation. They also assist in equalizing sinus pressures and avoiding sinus barotraumas.
Other techniques (Toynbee, BTV) are effective if there is easy and frequent middle ear autoinflation. They either equalize the pressures passively or produce negative middle ear pressures. Wave action or descent can also cause a negative middle ear pressure with resultant congestion and Eustachian tube obstruction, and these techniques may aggravate this condition.
Experienced divers, who have mobile tympanic membranes, resembling small spinnakers, can often descend to great depths before they need to equalize their middle ear pressures. They also autoinflate their ears by using less pressure.
Most patients with an inability to autoinflate their middle ears who have been referred to the authors of this text have suffered more from inadequate diver instruction than from Eustachian tube obstruction. To ascertain the extent of this problem, 200 consecutive otoscopic examinations were recorded on potential diving candidates. Autoinflation was successful using the Valsalva, Toynbee, Lowry or Edmonds technique in 96 per cent of subjects, with 4 per cent unsuccessful in one or both ears.
Decongestants probably do work on the mucosal membranes and do improve nasal air flow, but their effect on the Eustachian tube is greater at the nasopharyngeal orifice. Thus, these drugs may be more effective in reducing descent than ascent middle ear barotrauma.
Some otologists have recommended the use of the pneumatic otoscope to demonstrate passive tympanic membrane movement. This instrument is certainly of value in assessing middle ear disease, but it is inadequate for diving assessment because it fails to demonstrate the procedure that is required, i.e. voluntary autoinflation of the middle ear.
Other investigations of more value in assessing middle ear autoinflation include the modified tympanogram (see Chapter 36) and examination of the Eustachian cushions with a fibre optic nasopharyngoscope.